SlideShare a Scribd company logo
International Journal of Electrical and Computer Engineering (IJECE)
Vol. 7, No. 2, April 2017, pp. 619~630
ISSN: 2088-8708, DOI: 10.11591/ijece.v7i2.pp619-630  619
Journal homepage: http://iaesjournal.com/online/index.php/IJECE
Development of Load Control Algorithm for PV Microgrid
Mohamad Haireen Bin Fatheli1
, Nur Izzati Zolkifri2
, Chin Kim Gan3
, Musa Bin Yusup Lada4
1
Transmission and International Network Management, Telekom Malaysia, Malaysia
1,2,3,4
Faculty of Electrical Engineering, UniversitiTeknikal Malaysia Melaka, Malaysia
Article Info ABSTRACT
Article history:
Received Aug 18 , 2016
Revised Nov 24, 2016
Accepted Dec 10, 2016
The variability of solar irradiance caused by weather conditions could result
in the mismatch between the solar PV generation and demand, particularly in
the microgrid context. This may lead to detrimental effects of over/under
voltage or over/under frequency. In this regard, this paper presents the
laboratory setup of a grid-connected PV inverter operating in islanding
condition. To achieve this, a load control algorithm is proposed to provide
autonomous real time demand control that follows the PV generation to
maintain generation-demand equilibrium requirement. Laboratory results
show that the proposed load control algorithm is capable to address the
voltage and the frequency violation in islanding condition, regardless of the
variation of irradiance and power generated by the PV sources.
Keyword:
Demand response
Microgrid
Solar PV system
Copyright © 2017 Institute of Advanced Engineering and Science.
All rights reserved.
Corresponding Author:
Chin Kim Gan,
Faculty of Electrical Engineering,
Universiti Teknikal Malaysia Melaka,
Hang Tuah Jaya, 76100, Durian Tunggal, Melaka, Malaysia.
Email: ckgan@utem.edu.my
1. INTRODUCTION
The demands forelectrical power these few years are increasing, which also see the increase of the
use of distributed generation (DG). Energy sources of DGs are divided into two, which are renewable and
fossil fuel energy. In order to minimize the utilization of oil and gas as the main source of power generation,
numerous researches and studies have been performed these recent years, concentrating on Renewable
Energy (RE) as an alternate generation.Renewable Energy Sources (RES), interfaced with power energy
conversion and integrated with the loads and energy storage system, enables the RES to serve as a Microgrid
that can work in a stand-alone or grid-connected mode operation [1], which makes the microgrid concept
become practical. Microgrid is defined as a system that comprises of distributed generation that is
interconnected with medium and low voltage distribution system for energy transfer to the grid in grid-
connected mode operation [2]. Microgrid offers mutual advantages in the context of the user and utility
service provider, while helping in preserving the environment through cleaner energy produced from the
RES, which is proven free from any environmental concern. From the user perspective, the establishment of
microgrid through the grid interface connection promises improvement on the network quality by providing
reactive and harmonic compensation [3], as well as reducing the impact of pollution to the environment and
the cost to the user through an incentive scheme introduced by the local energy commissions.
Photovoltaic (PV) generation is one of the popular renewable energies. Solar energy is inexhaustible
and effective to generate bulk supplies of electricity. However, PV generation type depends on the weather
condition, which implies the output power is not constant all the time. The introduction of PV grid-tie
inverter helps to overcome the constant output issue by providing integration of the PV power output with
utility in a grid system, compensating each other [4]. The role of grid-tie inverter is to convert the DC supply
or non-asynchronous supply into synchronous AC supply of voltages that could smoothly or easily
IJECE ISSN: 2088-8708 
Development of Load Control Algorithm for PV Microgrid (Mohamad Haireen Bin Fatheli)
620
interconnect with the utility supply [5]. Moreover, in grid interconnected mode, the inverter serves as a
current source to provide preset power to the grid [6].
PV grid-tie inverter is designed with an anti-islanding mode that prevents power from the inverter
being transmitted to the grid when the grid is disconnected. As a consequence, local load will be interrupted
indiscriminately, which incurs unnecessary outage following the grid outage [7]. Hence, the optimization of
energy is not fully utilized though the source is ready and available. The islanding offers a solution to this
problem through intentional islanding that allows the inverter to be working, supplying the power to the local
loads in this mode. However, the intentional islanding has a drawback, in which the solar energy fluctuates
over time, depending on the weather condition. Voltage and frequency in intentional islanding are risky in the
wake of the uncertainty of the PV supply. With regard to this, in this paper, a load control algorithm system
is presented in this paper, designed to address voltage and frequency stabilization issue, and further to
compensate the uncertain energy produced by the PV supply. The load control algorithm will serve as a load
management that follows generation, to provide protection to the local loads and PV system, respectively.
LABVIEW software has been incorporated with the Data Acquisition (DAQ) devices in this experiment to
measure the current and voltages of the PV and load system.
2. RESEARCH METHOD
2.1. Sunny Boy 2000 HF-US Grid-Tie PV Inverter
The Sunny Boy 2000 HFS-US is a PV inverter system which functions to convert direct current
(DC) of a PV array into alternating current (AC), to feed into the power distribution grid. The PV inverter
system operates on a load that resonates at 50Hz frequency, which matches the output of the PV inverter
perfectly. Due to the safety design, the Sunny Boy PV inverter is incorporates withan anti-islanding
protection algorithm system to prevent the PV inverter from transporting the supply when the grid is
disconnected. The Sunny Boy PV inverter will inject periodically both leading and lagging reactive current in
this anti-islanding algorithm to destabilize and de-energize from a balance islanding condition.
Although reconfiguration of the Sunny Boy PV inverter into the islanding is prevented
automatically in-system, it still can be configured to the islanding externally. The fundamental of the Sunny
Boy PV inverter operation is by having the load to resonate at 50 Hz frequency to match the PV inverter
output [8]. Injecting an external AC source with 50Hz frequency to the load until the source signal is
matched to the PV output will allow the Sunny Boy PV inverter to work in islanding mode. In this
experiment, reconfiguration into the islanding mode was conducted by isolating the grid supply manually. A
reference signal from the external source was injected to the PCC until the signal matched the output of the
Sunny Boy PV inverter. Then, the Sunny Boy PV inverter could be configured to an intentional islanding
mode [9].
2.2. Point of Common Coupling (PCC)
PCC in this experiment provided a common point for the PV inverter and utility supply to
synchronize. The PCC functioned as a base of the access point for direct measurement between these two
supplies. The PCC was designed with the circuit breaker protection, to prevent over-current fault from
damaging the system [10]. Terminal Blocks were attached to the DIN-Rail and mounted on the board to
provide accessibility to the source which was interfaced in the PCC. The PCC electrical diagram is shown in
Figure 1(a). The hardware implementation is shown in Figure 1(b).
(a) (b)
Figure 1. (a) PCC electrical diagram, (b) PCC hardware implementation
 ISSN:2088-8708
IJECE Vol. 7, No. 2, April 2017 : 619–630
621
2.3. Isolation Transformer
Isolation transformer was employed in this experiment to isolate the output neutral of the PV
inverter system from the voltage source supply, where the voltage source supply served as a reference signal
in intentional islanding mode. The PV inverter and reference voltage supply were merged together in the
PCC board in an intentional islanding environment. Whenever two sources merged together, there would be
twoneutral inputs and a single output neutral connection, as illustrated in Figure 2(a). This led to the problem
of how to connect a single output neutral, given with two inputs neutral at the same time.
Combining these two sources does not require their neutrals to be connected together. Connecting
the inputs neutral together to the output neutral can create circulating current between the input neutrals, as
shown in Figure 2(b), which can be hazardous if two inputs neutral come from the different sources. An
isolation transformer placed in series at one of the sources should provide the solution to this problem. The
isolation transformer serves as a medium to electrically separate one of the neutral input wires coming from
the two different sources. As a result, only one input neutral wire is connected to the output neutral wire
directly. In this experiment, neutral input from the voltage source was electrically separated using the
isolation transformer, which enabled the neutral input from the PV inverter system to be connected directly to
the output neutral to the load.
(a) (b)
Figure 2. (a) Two inputs neutral and a single output neutral, (b) Circulate current between inputs neutral
2.4. Load Bank
Constant load at 1000W single phase was set in this experiment with the intention to observe the
effects of the fluctuating PV supply to the constant loads. Three-phase load bank was utilized in this
experiment and the load was recalculated to be set in this load bank accordingly. This was because the load
required in this experiment should be in a single phase while the load bank utilized was a three phase load
system.
The load bank utilized in this experiment had a balance load whose phase impedances were equal in
magnitude and phase. The resistance value of the load bank is given in wattage (W). As the load was
balanced in a three-phase load bank, conversion of three-phase loadinto the single phase load was done as in
Equation 1:
Pload 1Ø (1)
2.5. Development of Load Control Algorithm Software
Development of a load control algorithm system is divided into two, which are software design, that
acts as a brain to the load control algorithm, and hardware implementation, that demonstrates the
effectiveness of the load algorithm. The algorithm flow chart is developed as guidance to the software
development. Figure 3 below shows the algorithm flow chart developed for this load control system.
The algorithm flowchart in Figure 3 starts with the measurement of the current from PV inveter and
the load system. The algorithm program is developed to activate subject to the PV energy availability and
will be placed to off immediately once the PV energy has diminished. Then, the PV current is compared to
the load current. If the PV current is higher than the load current and meets the time delay set at respective
IJECE ISSN: 2088-8708 
Development of Load Control Algorithm for PV Microgrid (Mohamad Haireen Bin Fatheli)
622
individual load, the load will be connected sequentially. However, if the PV current is lower than the current
load in turn, the algorithm flow chart will measure the difference between the load current and the PV
current, respectively. The difference of the value is then compared with the threshold value. If the difference
current is greater than the threshold value given, load will be shed accordingly, or else the amount of the load
will be retained as it has been connected. The algorithm is a continuous process as long as PV energy is
present. LABVIEW software is incorporated with the Data Acquisition (DAQ) devices to measure the
current and voltages of the PV and load system.
Figure 3. Algorithm flow chart for load control system
A single channel configuration with a complete load control algorithm system for the experimental
setup is shown in Figure 4. DAQ Assistant is utilized as a single simulated device to measure three
parameters in the live system, namely, PCC Voltage, PV current and load current, respectively. Select
Signals VI is employed in this software configuration to split up the three parameters measured using a single
DAQ Assistant.
 ISSN:2088-8708
IJECE Vol. 7, No. 2, April 2017 : 619–630
623
Figure 4. Single channel of load control algorithm system
The hardware devices for load control algorithm system are listed in Table 1, which include the
Point of Common Coupling (PCC) with the circuit breakers protection, isolation transformer, low voltage
(LV) step-down transformer, transducer, relay switching modules, National Instrument Data Acquisition (NI
DAQ), DC-DC converter, Buffer circuit, and LABVIEW programming,which all form a complete load
control algorithm system.
Figure 5 shows the load control algorithm block diagram established for this project.
Table 1. Hardware components for load control algorithm system
No. Hardware components Rating/Model Quantity
1 Isolation Transformer 240/240 V 1
2 LV step down transformer 240/6 V 1
3 Current Transducer 15 V, 20 A, LEM HY 20-P 2
4 Relay Switching Module 5V, 8-channel Relay Interface Board, 15-20mA Driver Current 2
5 Relay Switching Module 5V, 4-channel Relay Interface Board, 15-20mA Driver Current 1
6 NI compact DAQ Ethernet chassis NI 9181 4
7 Digital Output Module NI 9472 3
8 Analog Voltage Input Module NI 9205 1
9 NI Managed Ethernet Switch NI – MES 3980 1
10 Buffer Circuit 20 x1kΩ resistance circuit 1
11 DC-DC Converter 1A, 12/5 V 1
12 AC/DC Enclosed Switching Dual Power Supply 10A, 240Vac/12Vdc 1
IJECE ISSN: 2088-8708 
Development of Load Control Algorithm for PV Microgrid (Mohamad Haireen Bin Fatheli)
624
Figure 5. Load control algorithm block diagram
2.5.1. LABVIEW Software Load Control Algorithm
In this experiment, LABVIEW software was incorporated with the Data Acquisition (DAQ) devices
to measure the currents and voltages of the PV and load system. The measured parameters data were then
transferred to the control application design in the LABVIEW code, to process the inputs following the
designated algorithm software and generate digital output signals to trigger the relay function of a load
control system. LABVIEW software has two panel architectures, namely the front panel and the block
diagram panel. The front panel serves to define the algorithm interface, which in this experiment functioned
to monitor the software interface and measured parameters.
Figure 6 shows the front panel of the LABVIEW software.
Figure 6. Front panel of LABVIEW software
2.6. Experimental Setup
The actual experimental was carried out by configuring the PV inverter system operating in the
islanding mode. To ensure the transition of the grid connected to the islanding mode be successful, a load
bank was utilized to match the output generated by the PV system, while waiting the load algorithm system
to initiate. Otherwise, the transition would not be successful while conducting experiment at the peak output
 ISSN:2088-8708
IJECE Vol. 7, No. 2, April 2017 : 619–630
625
of the PV system. Figure 7 shows the hardware experimental setup. The novelty of this experimental setup is
that the configuration allows the grid-tie inverter to operate in islanding mode with the source of reference
voltage. For simplicity, we considered the utility as the reference voltage, which can be replaced by other
tupes of AC power source.
Figure 7. Hardware experimental setup
3. RESULTS AND ANALYSIS
3.1. Intentional - Islanding With the Load Control Algorithm System
The load control algorithm is a designated system that controls the amount of the load to be
connected corresponding to the PV generation level. The load control algorithm system monitors the
magnitude of current delivered to the load, and controls the energy balance between the PV generation and
load demand respectively.
3.1.1. Load Demand Follow the PV Generation
PV inverter current and load current are two parameters which were monitored and controlled in this
algorithm design. The load current was designed to follow the PV current, as shown in Figure 8. Load
demand parallel with generation was successfully established in the actual system test operating in islanding
mode, producing load current corresponding to PV current change.
The algorithm design managed to control the load amount according to the PV generation level by
controlling the load current which continuously followed the PV current all the time. However, at certain
operation cycle, it was found that the load current encountered fluctuation for a few seconds before resuming
normal operation. Fluctuations occurred due to the hardware timing of data acquisition (DAQ) that was not
synchronized with the software timing. Never the less, the fluctuation could be minimized by introducing
time delay to the software program.
As a result of the mismatch of the software and hardware timing, fluctuation occurred since the
relay switching module was supplied with intermittent signal from the DAQ modules. Furthermore, the DAQ
modules permitted the relay operation to intermittently operate until the mismatch between the software and
hardware timing was rectified through self synchronization on these two timings accordingly. The load
current was higher in the graph presented, as a sign to prevent reverse current from propagating into the
external voltage source. The load was slightly higher from the PV current designed in the algorithm as a
security assurance to prevent reverse power flow from occurring. Regardless of the intermittent of the PV
supply, the load could be controlled for the amount of the PV supply generated. Unlike microgrid
PV panel
Grid-tie Inverter
Distribution
Board
Point of Commo n
Coupling (PCC)
Isolation
Transformer
TNB single
phase supply
LABVIEW
monitoring and
controlling
Load control
Algorithm
Bulbs Load
Load Bank
IJECE ISSN: 2088-8708 
Development of Load Control Algorithm for PV Microgrid (Mohamad Haireen Bin Fatheli)
626
experimental setup using solar power emulator [11], actual working PV system with real connected loads was
considered in this work.
Figure 8. Load current follow PV current generation
3.1.2. Voltage Stability Offered by Load Control System
Figure 9 shows the load voltage measured in islanding mode with the load control algorithm system.
The voltage can be briefly described as with the load control system, the load voltage was observed operating
in +10%, -6% voltage limit [12] and free from any voltage violation in islanding.
Figure 9. Load voltage operating in islanding with load control system
Figure 10 shows irradiance as a variable parameter. The fluctuation of irradiance energy was due to
the weather and global sun position, which implies that the PV source is not a constant type of energy, thus
posing reliability issues in power generation [13].
The irradiance energy was then transformed into DC input of the PV inverter, where the energy
conversion output was in AC waveform, as shown in Figure 11. The AC voltage declined excessively at the
beginning of the operational cycle because the transition from grid was disconnected to the islanding mode.
Nevertheless, the DC voltage could be kept constant, mainly due to the Maximum Power Point Tracking
(MPPT) that maximized the power output in event of irradiance fluctuation.
The AC voltage successfully controlled working at voltage limit, free from any voltage violence. In
spite of fluctuation due to weather variances affecting the input PV inverter, which was unmanageable by the
MPPT, the voltage could still be retained as constant due to the aids of the load control algorithm system.
Hence, the PV inverter current source proves fit to workin islanding environment.
Fluctuation due to mismatch of hardware
and software timing
 ISSN:2088-8708
IJECE Vol. 7, No. 2, April 2017 : 619–630
627
Figure 10. Irradiance data
Figure 11. DC and AC voltage PV inverter system
3.1.3. Frequency Stability Offered by Load Control System
Figure 12 shows the load frequency showing with the load control algorithm system, in which
frequency was operated in limit from 49.5Hz to 50.5Hz [14] and immune from any gradual changes in the
course of unreliable source provided by the PV system in islanding.
Figure 12. Load frequency measured
Transition from grid
disconnected to island
mode
IJECE ISSN: 2088-8708 
Development of Load Control Algorithm for PV Microgrid (Mohamad Haireen Bin Fatheli)
628
3.2. PV Inverter Current Distortion
The measured PV inverter current and the load current are shown in Figure 13. It was observed that
the inverter current waveform was in a form of distorted signal, while the load current waveform was purely
in sinusoidal from.
The degree of distortion was due to the harmonic presence, showed when significant distorted signal
was encountered and when low PV supply was generated to the load. At this time, the PV inverter operated
with low power conversion where the distortion was very high [15] [16]. The external voltage source in turn,
provided the necessary current that mixed up with the distorted current from the PV inverter, producing pure
sinusoidal waveform to the load. Thus, power quality was preserved in good quality to the load.
Figure 13. PV inverter current and load current
Figure 14 shows the irradiance data against temperature, showing that distorted signal appeared at
low irradiance, proportional to the low panel temperature. The relation shows that when temperature rises,
the irradiance will rise as well [17]. As such, the inverter would have problems producing good power quality
if it had worked as a standalone system. The function of external voltage in this experiment was to ensure
good power quality be delivered to the load, providing compensation to the distorted signal at the time of the
irradiance energy being low.
Figure 14. Irradiance versus temperature
The results showed that the load current followed the PV current continuously all the time until the
PV supply was dismissed. The voltage was constantly stable at the point of PCC, as the load was connected
based on the PV generation level, which prevented any over-voltage or under-voltage scenario from
 ISSN:2088-8708
IJECE Vol. 7, No. 2, April 2017 : 619–630
629
occurring. Hence, the load control algorithm system, instead of addressing the stability issue in the
intentional islanding from the context of voltage and frequency, also provided protection from over-voltage
or under-voltage to the load and PV supply at the same time. It has been proven that the load control
algorithm system can effectively control the load in actual test of grid connected PV system for PV microgrid
restoration, which is in line with the objective of this paper.
4. CONCLUSION
Variability of solar irradiance due to weather condition could result in the mismatch between solar
PV generation and demand, particularly in the microgrid context. This may lead to detrimental effects of
over/under voltage or over/under frequency. As proven in this study, the developed load control algorithm is
able to accommodate PV generation operating in intentional-islanding mode. The load control algorithm
system will maintain demand-supply in a balance condition, by usinga switch relay control that connects the
loads according to the PV generation level. The load control algorithm system has been successfully designed
using LABVIEW software to form a complete and autonomous load control algorithm system to control the
load presence in accordance to the PV generation.
ACKNOWLEDGEMENTS
The authors gratefully acknowledge the financial support provided by the Ministry of Higher
Education Malaysia under the Research Grant: RAGS/1/2015/TK03/FKE/03/B00096. Special appreciation
and gratitude are expressed to the Center of Robotics and Industrial Automation (CeRIA), Centre of Research
and Innovation Management (CRIM) and Faculty of Electrical Engineering (FKE) ofUTeM for giving the
financial and moral support forsuccessful completion of this project.
REFERENCES
[1] Barnes, M., Dimeas, A., Engler, A., Fitzer, C., Hatziargryriou, N., Papathanassiou, S., Vandenbergh, M., 2005,
“Microgrid laboratory facilities”, International Conference on Future Power Systems, pp. 1–6.
[2] Trujillio Rodriguez, C., Velasco de la Fuente, D., Garcera, G., Figueres, E., Guacaneme Moreno, J.A., 2013,
“Reconfigurable Control Scheme for a PV Microinverter Working in Both Grid-Connected and Island Modes”,
IEEE Transactions on Industrial Electronics, 60(4), pp 1582-1595.
[3] Dall’Anese, E., and Gianakis, G.B., 2014, “Risk-Constrained Microgrid Reconfiguration Using Group Sparsity”,
IEEE Transactions on Sustainable Energy, 5(4), pp. 1415-1425.
[4] Hartono, B.S., Budiyanto, Y., Setiabudy, R., 2013, “Review of Microgrid Technology”, International Conference on
QiR (Quality in Research), pp. 127-132.
[5] IEEE.Standards-1547.2, 2008. IEEE Application Guide for IEEE STD 1547TM, IEEE Standard for Interconnecting
Distributed Resources with Electric Power Systems. IEEE Standards Coordinating Committee 21. [Online]
Available from: http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4816078 [Accessed: 12 December 2014].
[6] Wandhare, R.G., Thale, S., Agarwal, V., 2014, “Design of Photovoltaic Power Conditioning System for
Hierarchical Control of a Microgri”, IEEE 40th Photovoltaic Specialist Conference (PVSC), pp 3144-3149.
[7] M. Shamshiri, C. K. Gan and Chee Wei Tan, "A review of recent development in smart grid and micro-grid
laboratories," Power Engineering and Optimization Conference (PEOCO) Melaka, Malaysia, 2012 IEEE
International, Melaka, 2012, pp. 367-372.
[8] Guo, Xiao-Qiang., Wu, Wei-Yang., Gu, He-Rong., 2011, “Phase Locked Loop and Synchronization Methods for
Grid-Interfaced Converters: A Review”, [Online] Available at: www.red.pe.org.pl/articles/2011/4/48.pdf [Accessed
on 12 February 2014]
[9] Kotsopoulos, A., Duarte, J.L., Hendrix, M.A.M., Heskes, P.J.M., 2002, “Islanding behaviour of grid connected PV
inverters operating under different control schemes”, IEEE 33rd Power Electronics Specialists Conference, 2002,
2002(3), pp. 1506-1511.
[10] ALLEN-BRADLEY-CB. Application, 1994. Using Circuit Breakers to Protect Transformer Circuits. ALLEN-
BRADLEY.
[11] R.R. Islam, M. Liao, T.H. Vo and J. Ravishankar, "Experimental setup of a microgrid with wind and solar power
emulators," Electrical Energy Systems (ICEES), 2014 IEEE 2nd International Conference on, Chennai, 2014, pp. 9-
14.
[12] Tenaga Nasional Berhad, “Electricity Supply Application Handbook”, 3rd ed. 2011. [Online]
https://www.tnb.com.my/assets/files/ESAHv3.pdf]
[13] Afroze, S., Udaykumar, R.Y., Naik, A., 2012, “A Systematic Approach to Grid Connected PV system”, IEEE 5th
Power India Conference, pp. 1-5.
[14] Johari, A., 2010. The Malaysian Grid Code. [Online]. 2010. Available from:
http://www.tnb.com.my/tnb/application/uploads/uploaded/the Malaysian grid code.pdf.
IJECE ISSN: 2088-8708 
Development of Load Control Algorithm for PV Microgrid (Mohamad Haireen Bin Fatheli)
630
[15] Hamid, M.I., and Jusoh, A., 2014, “Reduction of Waveform Distortion in Grid-Injection Current from Single Phase
Utility Interactive PV-Inverter”, Energy Conversion and Management, pp. 212-226.
[16] M. Ayub, C.K. Gan and A.F.A. Kadir, "The impact of grid-connected PV systems on Harmonic Distortion," 2014
IEEE Innovative Smart Grid Technologies - Asia (ISGT ASIA), Kuala Lumpur, 2014, pp. 669-674.
[17] Anonymous, 2010, “Coordinated Control Scheme for Standalone PV System with Nonlinear Load”, IEEE PES
Transmission and Distribution Conference and Exposition, pp. 1-8.
[18] M. Abdulkadir, A.S. Samosir, A.H.M. Yatim, 2013, “Modeling and Simulation of Solar Photovoltaic System, Its
Dynamics and Transient Characteristics in LABVIEW”, International Journal of Power Electronics and Drive
System (IJPEDS), pp. 185-192.
[19] Himanshu Sharma, Nitai Pal, Yaduvir Singh, Pradip Kumar Sadhu, 2015, “Development nd Simulation of Stand
Alone Photovoltaic Model Using Matlab/Simulink”, International Journal of Power Electronics and Drive System
(IJPEDS), Vol.6, No. 4, pp. 703-711.
[20] Yafaoui, A., Bin Wu, Kouro, S., 2012, “Improved Active Frequency Drift Anti-islanding Detection Method for
Grid Connected Photovoltaic Systems”, IEEE Transactions on Power Electronics, 27(5), pp. 2367-2375.
[21] Xin Chen., Yan Hong Wan., Yun Cheng Wang., 2013, “A Novel Seamless Transferring Control Method for
Microgrid Based on Master-Slave Configuration.”,2013 IEEE ECCE Asia Downunder (ECCE Asia) 2013,
pp. 351-357.
[22] Liu Jie, Yang Haizhu, 2009, “Anti-Islanding Control of Grid Connected Photovoltaic Inverter Based on Positive
Feedback Frequency Drift”, IEEE 6th International Power Electronics and Motion Control Conference,
pp. 2147-2150.

More Related Content

What's hot (20)

PDF
Final talk trident-05-10-2021- dr p k rout-converted
Siksha 'O' Anusandhan (Deemed to be University )
 
PDF
Control for Grid-Connected and Intentional Islanding Operations of Distribute...
Asoka Technologies
 
PPTX
anti islanding technology(passive)
minu Yacob
 
PDF
Optimal placement of distributed power flow controller for loss reduction usi...
eSAT Journals
 
PDF
www.ijerd.com
IJERD Editor
 
PDF
Impacts of Photovoltaic Distributed Generation Location and Size on Distribut...
International Journal of Power Electronics and Drive Systems
 
PDF
Energy Management of Distributed Generation Inverters using MPC Controller i...
IJMER
 
PDF
Power Quality Improvement with Multilevel Inverter Based IPQC for Microgrid
IJMTST Journal
 
PDF
Electric Vehicle as an Energy Storage for Grid Connected Solar Power System
IAES-IJPEDS
 
PPSX
Presentation o An Intelligent protection scheme for microgrid using data-mini...
Sima Aznavi
 
PPTX
Islands in power systems
Sudhanshu Sharma
 
PDF
Optimal Siting And Sizing Of Distributed Generation For Radial Distribution S...
inventy
 
PDF
Genetic Algorithm based Optimal Placement of Distributed Generation Reducing ...
IDES Editor
 
PPSX
Presentation, IEEE ENERGY CONVERSION CONGRESS & EXPO 2018
Sima Aznavi
 
PDF
Iaetsd integration of distributed solar power generation
Iaetsd Iaetsd
 
PDF
Design & Analysis of Grid Connected Photovoltaic System
Sulaman Muhammad
 
PPTX
A Review of Protection Schemes for Active Distribution Systems
Umair Shahzad
 
PDF
L01052101108
IOSR Journals
 
PPTX
Control of parallel dc dc converters in a dc microgrid
Sushil Aggarwal
 
PPTX
Island Detection and Control Techniques
Tanveer Riaz
 
Final talk trident-05-10-2021- dr p k rout-converted
Siksha 'O' Anusandhan (Deemed to be University )
 
Control for Grid-Connected and Intentional Islanding Operations of Distribute...
Asoka Technologies
 
anti islanding technology(passive)
minu Yacob
 
Optimal placement of distributed power flow controller for loss reduction usi...
eSAT Journals
 
www.ijerd.com
IJERD Editor
 
Impacts of Photovoltaic Distributed Generation Location and Size on Distribut...
International Journal of Power Electronics and Drive Systems
 
Energy Management of Distributed Generation Inverters using MPC Controller i...
IJMER
 
Power Quality Improvement with Multilevel Inverter Based IPQC for Microgrid
IJMTST Journal
 
Electric Vehicle as an Energy Storage for Grid Connected Solar Power System
IAES-IJPEDS
 
Presentation o An Intelligent protection scheme for microgrid using data-mini...
Sima Aznavi
 
Islands in power systems
Sudhanshu Sharma
 
Optimal Siting And Sizing Of Distributed Generation For Radial Distribution S...
inventy
 
Genetic Algorithm based Optimal Placement of Distributed Generation Reducing ...
IDES Editor
 
Presentation, IEEE ENERGY CONVERSION CONGRESS & EXPO 2018
Sima Aznavi
 
Iaetsd integration of distributed solar power generation
Iaetsd Iaetsd
 
Design & Analysis of Grid Connected Photovoltaic System
Sulaman Muhammad
 
A Review of Protection Schemes for Active Distribution Systems
Umair Shahzad
 
L01052101108
IOSR Journals
 
Control of parallel dc dc converters in a dc microgrid
Sushil Aggarwal
 
Island Detection and Control Techniques
Tanveer Riaz
 

Similar to Development of Load Control Algorithm for PV Microgrid (20)

PDF
Stability analysis of photovoltaic system under grid faults
International Journal of Power Electronics and Drive Systems
 
PDF
Design and Development of Grid-connected Quasi-Z-Source PV Inverter
International Journal of Power Electronics and Drive Systems
 
PDF
Review of Maximum Power Point Tracking Based PV Array to Produce Electric Energy
IRJET Journal
 
PDF
HYBRID SOLAR-WIND CHARGING STATION FOR ELECTRIC VEHICLES AND ITS SIMULATION
IRJET Journal
 
PDF
Droop control technique for equal power sharing in islanded microgrid
International Journal of Power Electronics and Drive Systems
 
PDF
Power Flow Control for Dc Microgrid Using MPPT Technique
IRJET Journal
 
PDF
CONTROL STRATEGIES ON GRID-TIED PV INVERTERS
IRJET Journal
 
PDF
IRJET- Power Quality Improvement in Solar by using Fuzzy Logic Controller
IRJET Journal
 
PDF
Hybrid bypass technique to mitigate leakage current in the grid-tied inverter
IJECEIAES
 
PDF
Performance Analysis of DC Micro Grid with PV-Fuel Cell Hybrid Generation
IJMREMJournal
 
PDF
C011141018
IOSR Journals
 
PDF
Design_and_Investigation_of_FRT_Schemes_for_Three-Phase_Grid-Tied_PV_System.pdf
Engnr Kami Zeb
 
PDF
A Flexible AC Distribution System for a Microgrid with a Photovoltaic System ...
IJMTST Journal
 
PDF
Control strategies for seamless transfer between the grid-connected and isla...
IJECEIAES
 
PDF
Control of Two Stage PV Power System under the Unbalanced Three Phase Grid Vo...
ijtsrd
 
PDF
Design and Simulation of DC Microgrid with DC-DC Bi-directional Converter
IRJET Journal
 
PDF
A modern two dof controller for grid integration with solar power generator
iaemedu
 
PDF
IRJET- Photovoltaic 10MW Power Plant Simulation & Design using Mathwork &...
IRJET Journal
 
PDF
Comparison of upqc and dvr in wind turbine fed fsig under asymmetric faults
elelijjournal
 
PDF
IRJET- Renewable Energy Hybrid Power System with Improvement of Power Quality...
IRJET Journal
 
Stability analysis of photovoltaic system under grid faults
International Journal of Power Electronics and Drive Systems
 
Design and Development of Grid-connected Quasi-Z-Source PV Inverter
International Journal of Power Electronics and Drive Systems
 
Review of Maximum Power Point Tracking Based PV Array to Produce Electric Energy
IRJET Journal
 
HYBRID SOLAR-WIND CHARGING STATION FOR ELECTRIC VEHICLES AND ITS SIMULATION
IRJET Journal
 
Droop control technique for equal power sharing in islanded microgrid
International Journal of Power Electronics and Drive Systems
 
Power Flow Control for Dc Microgrid Using MPPT Technique
IRJET Journal
 
CONTROL STRATEGIES ON GRID-TIED PV INVERTERS
IRJET Journal
 
IRJET- Power Quality Improvement in Solar by using Fuzzy Logic Controller
IRJET Journal
 
Hybrid bypass technique to mitigate leakage current in the grid-tied inverter
IJECEIAES
 
Performance Analysis of DC Micro Grid with PV-Fuel Cell Hybrid Generation
IJMREMJournal
 
C011141018
IOSR Journals
 
Design_and_Investigation_of_FRT_Schemes_for_Three-Phase_Grid-Tied_PV_System.pdf
Engnr Kami Zeb
 
A Flexible AC Distribution System for a Microgrid with a Photovoltaic System ...
IJMTST Journal
 
Control strategies for seamless transfer between the grid-connected and isla...
IJECEIAES
 
Control of Two Stage PV Power System under the Unbalanced Three Phase Grid Vo...
ijtsrd
 
Design and Simulation of DC Microgrid with DC-DC Bi-directional Converter
IRJET Journal
 
A modern two dof controller for grid integration with solar power generator
iaemedu
 
IRJET- Photovoltaic 10MW Power Plant Simulation & Design using Mathwork &...
IRJET Journal
 
Comparison of upqc and dvr in wind turbine fed fsig under asymmetric faults
elelijjournal
 
IRJET- Renewable Energy Hybrid Power System with Improvement of Power Quality...
IRJET Journal
 
Ad

More from IJECEIAES (20)

PDF
Redefining brain tumor segmentation: a cutting-edge convolutional neural netw...
IJECEIAES
 
PDF
Embedded machine learning-based road conditions and driving behavior monitoring
IJECEIAES
 
PDF
Advanced control scheme of doubly fed induction generator for wind turbine us...
IJECEIAES
 
PDF
Neural network optimizer of proportional-integral-differential controller par...
IJECEIAES
 
PDF
An improved modulation technique suitable for a three level flying capacitor ...
IJECEIAES
 
PDF
A review on features and methods of potential fishing zone
IJECEIAES
 
PDF
Electrical signal interference minimization using appropriate core material f...
IJECEIAES
 
PDF
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...
IJECEIAES
 
PDF
Bibliometric analysis highlighting the role of women in addressing climate ch...
IJECEIAES
 
PDF
Voltage and frequency control of microgrid in presence of micro-turbine inter...
IJECEIAES
 
PDF
Enhancing battery system identification: nonlinear autoregressive modeling fo...
IJECEIAES
 
PDF
Smart grid deployment: from a bibliometric analysis to a survey
IJECEIAES
 
PDF
Use of analytical hierarchy process for selecting and prioritizing islanding ...
IJECEIAES
 
PDF
Enhancing of single-stage grid-connected photovoltaic system using fuzzy logi...
IJECEIAES
 
PDF
Enhancing photovoltaic system maximum power point tracking with fuzzy logic-b...
IJECEIAES
 
PDF
Adaptive synchronous sliding control for a robot manipulator based on neural ...
IJECEIAES
 
PDF
Remote field-programmable gate array laboratory for signal acquisition and de...
IJECEIAES
 
PDF
Detecting and resolving feature envy through automated machine learning and m...
IJECEIAES
 
PDF
Smart monitoring technique for solar cell systems using internet of things ba...
IJECEIAES
 
PDF
An efficient security framework for intrusion detection and prevention in int...
IJECEIAES
 
Redefining brain tumor segmentation: a cutting-edge convolutional neural netw...
IJECEIAES
 
Embedded machine learning-based road conditions and driving behavior monitoring
IJECEIAES
 
Advanced control scheme of doubly fed induction generator for wind turbine us...
IJECEIAES
 
Neural network optimizer of proportional-integral-differential controller par...
IJECEIAES
 
An improved modulation technique suitable for a three level flying capacitor ...
IJECEIAES
 
A review on features and methods of potential fishing zone
IJECEIAES
 
Electrical signal interference minimization using appropriate core material f...
IJECEIAES
 
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...
IJECEIAES
 
Bibliometric analysis highlighting the role of women in addressing climate ch...
IJECEIAES
 
Voltage and frequency control of microgrid in presence of micro-turbine inter...
IJECEIAES
 
Enhancing battery system identification: nonlinear autoregressive modeling fo...
IJECEIAES
 
Smart grid deployment: from a bibliometric analysis to a survey
IJECEIAES
 
Use of analytical hierarchy process for selecting and prioritizing islanding ...
IJECEIAES
 
Enhancing of single-stage grid-connected photovoltaic system using fuzzy logi...
IJECEIAES
 
Enhancing photovoltaic system maximum power point tracking with fuzzy logic-b...
IJECEIAES
 
Adaptive synchronous sliding control for a robot manipulator based on neural ...
IJECEIAES
 
Remote field-programmable gate array laboratory for signal acquisition and de...
IJECEIAES
 
Detecting and resolving feature envy through automated machine learning and m...
IJECEIAES
 
Smart monitoring technique for solar cell systems using internet of things ba...
IJECEIAES
 
An efficient security framework for intrusion detection and prevention in int...
IJECEIAES
 
Ad

Recently uploaded (20)

PDF
FSE-Journal-First-Automated code editing with search-generate-modify.pdf
cl144
 
PDF
Tesia Dobrydnia - An Avid Hiker And Backpacker
Tesia Dobrydnia
 
PDF
PRIZ Academy - Process functional modelling
PRIZ Guru
 
PPTX
ASBC application presentation template (ENG)_v3 (1).pptx
HassanMohammed730118
 
PPTX
Artificial Intelligence jejeiejj3iriejrjifirirjdjeie
VikingsGaming2
 
PDF
Decision support system in machine learning models for a face recognition-bas...
TELKOMNIKA JOURNAL
 
PDF
Generative AI & Scientific Research : Catalyst for Innovation, Ethics & Impact
AlqualsaDIResearchGr
 
PPTX
Unit_I Functional Units, Instruction Sets.pptx
logaprakash9
 
PDF
تقرير عن التحليل الديناميكي لتدفق الهواء حول جناح.pdf
محمد قصص فتوتة
 
PPTX
Bharatiya Antariksh Hackathon 2025 Idea Submission PPT.pptx
AsadShad4
 
PDF
Artificial Neural Network-Types,Perceptron,Problems
Sharmila Chidaravalli
 
PPTX
Functions in Python Programming Language
BeulahS2
 
PPTX
Comparison of Flexible and Rigid Pavements in Bangladesh
Arifur Rahman
 
PPTX
CST413 KTU S7 CSE Machine Learning Neural Networks and Support Vector Machine...
resming1
 
PPTX
Stability of IBR Dominated Grids - IEEE PEDG 2025 - short.pptx
ssuser307730
 
PPT
دراسة حاله لقرية تقع في جنوب غرب السودان
محمد قصص فتوتة
 
PPTX
Explore USA’s Best Structural And Non Structural Steel Detailing
Silicon Engineering Consultants LLC
 
PDF
NFPA 10 - Estandar para extintores de incendios portatiles (ed.22 ENG).pdf
Oscar Orozco
 
PDF
Module - 4 Machine Learning -22ISE62.pdf
Dr. Shivashankar
 
PDF
June 2025 Top 10 Sites -Electrical and Electronics Engineering: An Internatio...
elelijjournal653
 
FSE-Journal-First-Automated code editing with search-generate-modify.pdf
cl144
 
Tesia Dobrydnia - An Avid Hiker And Backpacker
Tesia Dobrydnia
 
PRIZ Academy - Process functional modelling
PRIZ Guru
 
ASBC application presentation template (ENG)_v3 (1).pptx
HassanMohammed730118
 
Artificial Intelligence jejeiejj3iriejrjifirirjdjeie
VikingsGaming2
 
Decision support system in machine learning models for a face recognition-bas...
TELKOMNIKA JOURNAL
 
Generative AI & Scientific Research : Catalyst for Innovation, Ethics & Impact
AlqualsaDIResearchGr
 
Unit_I Functional Units, Instruction Sets.pptx
logaprakash9
 
تقرير عن التحليل الديناميكي لتدفق الهواء حول جناح.pdf
محمد قصص فتوتة
 
Bharatiya Antariksh Hackathon 2025 Idea Submission PPT.pptx
AsadShad4
 
Artificial Neural Network-Types,Perceptron,Problems
Sharmila Chidaravalli
 
Functions in Python Programming Language
BeulahS2
 
Comparison of Flexible and Rigid Pavements in Bangladesh
Arifur Rahman
 
CST413 KTU S7 CSE Machine Learning Neural Networks and Support Vector Machine...
resming1
 
Stability of IBR Dominated Grids - IEEE PEDG 2025 - short.pptx
ssuser307730
 
دراسة حاله لقرية تقع في جنوب غرب السودان
محمد قصص فتوتة
 
Explore USA’s Best Structural And Non Structural Steel Detailing
Silicon Engineering Consultants LLC
 
NFPA 10 - Estandar para extintores de incendios portatiles (ed.22 ENG).pdf
Oscar Orozco
 
Module - 4 Machine Learning -22ISE62.pdf
Dr. Shivashankar
 
June 2025 Top 10 Sites -Electrical and Electronics Engineering: An Internatio...
elelijjournal653
 

Development of Load Control Algorithm for PV Microgrid

  • 1. International Journal of Electrical and Computer Engineering (IJECE) Vol. 7, No. 2, April 2017, pp. 619~630 ISSN: 2088-8708, DOI: 10.11591/ijece.v7i2.pp619-630  619 Journal homepage: http://iaesjournal.com/online/index.php/IJECE Development of Load Control Algorithm for PV Microgrid Mohamad Haireen Bin Fatheli1 , Nur Izzati Zolkifri2 , Chin Kim Gan3 , Musa Bin Yusup Lada4 1 Transmission and International Network Management, Telekom Malaysia, Malaysia 1,2,3,4 Faculty of Electrical Engineering, UniversitiTeknikal Malaysia Melaka, Malaysia Article Info ABSTRACT Article history: Received Aug 18 , 2016 Revised Nov 24, 2016 Accepted Dec 10, 2016 The variability of solar irradiance caused by weather conditions could result in the mismatch between the solar PV generation and demand, particularly in the microgrid context. This may lead to detrimental effects of over/under voltage or over/under frequency. In this regard, this paper presents the laboratory setup of a grid-connected PV inverter operating in islanding condition. To achieve this, a load control algorithm is proposed to provide autonomous real time demand control that follows the PV generation to maintain generation-demand equilibrium requirement. Laboratory results show that the proposed load control algorithm is capable to address the voltage and the frequency violation in islanding condition, regardless of the variation of irradiance and power generated by the PV sources. Keyword: Demand response Microgrid Solar PV system Copyright © 2017 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: Chin Kim Gan, Faculty of Electrical Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100, Durian Tunggal, Melaka, Malaysia. Email: [email protected] 1. INTRODUCTION The demands forelectrical power these few years are increasing, which also see the increase of the use of distributed generation (DG). Energy sources of DGs are divided into two, which are renewable and fossil fuel energy. In order to minimize the utilization of oil and gas as the main source of power generation, numerous researches and studies have been performed these recent years, concentrating on Renewable Energy (RE) as an alternate generation.Renewable Energy Sources (RES), interfaced with power energy conversion and integrated with the loads and energy storage system, enables the RES to serve as a Microgrid that can work in a stand-alone or grid-connected mode operation [1], which makes the microgrid concept become practical. Microgrid is defined as a system that comprises of distributed generation that is interconnected with medium and low voltage distribution system for energy transfer to the grid in grid- connected mode operation [2]. Microgrid offers mutual advantages in the context of the user and utility service provider, while helping in preserving the environment through cleaner energy produced from the RES, which is proven free from any environmental concern. From the user perspective, the establishment of microgrid through the grid interface connection promises improvement on the network quality by providing reactive and harmonic compensation [3], as well as reducing the impact of pollution to the environment and the cost to the user through an incentive scheme introduced by the local energy commissions. Photovoltaic (PV) generation is one of the popular renewable energies. Solar energy is inexhaustible and effective to generate bulk supplies of electricity. However, PV generation type depends on the weather condition, which implies the output power is not constant all the time. The introduction of PV grid-tie inverter helps to overcome the constant output issue by providing integration of the PV power output with utility in a grid system, compensating each other [4]. The role of grid-tie inverter is to convert the DC supply or non-asynchronous supply into synchronous AC supply of voltages that could smoothly or easily
  • 2. IJECE ISSN: 2088-8708  Development of Load Control Algorithm for PV Microgrid (Mohamad Haireen Bin Fatheli) 620 interconnect with the utility supply [5]. Moreover, in grid interconnected mode, the inverter serves as a current source to provide preset power to the grid [6]. PV grid-tie inverter is designed with an anti-islanding mode that prevents power from the inverter being transmitted to the grid when the grid is disconnected. As a consequence, local load will be interrupted indiscriminately, which incurs unnecessary outage following the grid outage [7]. Hence, the optimization of energy is not fully utilized though the source is ready and available. The islanding offers a solution to this problem through intentional islanding that allows the inverter to be working, supplying the power to the local loads in this mode. However, the intentional islanding has a drawback, in which the solar energy fluctuates over time, depending on the weather condition. Voltage and frequency in intentional islanding are risky in the wake of the uncertainty of the PV supply. With regard to this, in this paper, a load control algorithm system is presented in this paper, designed to address voltage and frequency stabilization issue, and further to compensate the uncertain energy produced by the PV supply. The load control algorithm will serve as a load management that follows generation, to provide protection to the local loads and PV system, respectively. LABVIEW software has been incorporated with the Data Acquisition (DAQ) devices in this experiment to measure the current and voltages of the PV and load system. 2. RESEARCH METHOD 2.1. Sunny Boy 2000 HF-US Grid-Tie PV Inverter The Sunny Boy 2000 HFS-US is a PV inverter system which functions to convert direct current (DC) of a PV array into alternating current (AC), to feed into the power distribution grid. The PV inverter system operates on a load that resonates at 50Hz frequency, which matches the output of the PV inverter perfectly. Due to the safety design, the Sunny Boy PV inverter is incorporates withan anti-islanding protection algorithm system to prevent the PV inverter from transporting the supply when the grid is disconnected. The Sunny Boy PV inverter will inject periodically both leading and lagging reactive current in this anti-islanding algorithm to destabilize and de-energize from a balance islanding condition. Although reconfiguration of the Sunny Boy PV inverter into the islanding is prevented automatically in-system, it still can be configured to the islanding externally. The fundamental of the Sunny Boy PV inverter operation is by having the load to resonate at 50 Hz frequency to match the PV inverter output [8]. Injecting an external AC source with 50Hz frequency to the load until the source signal is matched to the PV output will allow the Sunny Boy PV inverter to work in islanding mode. In this experiment, reconfiguration into the islanding mode was conducted by isolating the grid supply manually. A reference signal from the external source was injected to the PCC until the signal matched the output of the Sunny Boy PV inverter. Then, the Sunny Boy PV inverter could be configured to an intentional islanding mode [9]. 2.2. Point of Common Coupling (PCC) PCC in this experiment provided a common point for the PV inverter and utility supply to synchronize. The PCC functioned as a base of the access point for direct measurement between these two supplies. The PCC was designed with the circuit breaker protection, to prevent over-current fault from damaging the system [10]. Terminal Blocks were attached to the DIN-Rail and mounted on the board to provide accessibility to the source which was interfaced in the PCC. The PCC electrical diagram is shown in Figure 1(a). The hardware implementation is shown in Figure 1(b). (a) (b) Figure 1. (a) PCC electrical diagram, (b) PCC hardware implementation
  • 3.  ISSN:2088-8708 IJECE Vol. 7, No. 2, April 2017 : 619–630 621 2.3. Isolation Transformer Isolation transformer was employed in this experiment to isolate the output neutral of the PV inverter system from the voltage source supply, where the voltage source supply served as a reference signal in intentional islanding mode. The PV inverter and reference voltage supply were merged together in the PCC board in an intentional islanding environment. Whenever two sources merged together, there would be twoneutral inputs and a single output neutral connection, as illustrated in Figure 2(a). This led to the problem of how to connect a single output neutral, given with two inputs neutral at the same time. Combining these two sources does not require their neutrals to be connected together. Connecting the inputs neutral together to the output neutral can create circulating current between the input neutrals, as shown in Figure 2(b), which can be hazardous if two inputs neutral come from the different sources. An isolation transformer placed in series at one of the sources should provide the solution to this problem. The isolation transformer serves as a medium to electrically separate one of the neutral input wires coming from the two different sources. As a result, only one input neutral wire is connected to the output neutral wire directly. In this experiment, neutral input from the voltage source was electrically separated using the isolation transformer, which enabled the neutral input from the PV inverter system to be connected directly to the output neutral to the load. (a) (b) Figure 2. (a) Two inputs neutral and a single output neutral, (b) Circulate current between inputs neutral 2.4. Load Bank Constant load at 1000W single phase was set in this experiment with the intention to observe the effects of the fluctuating PV supply to the constant loads. Three-phase load bank was utilized in this experiment and the load was recalculated to be set in this load bank accordingly. This was because the load required in this experiment should be in a single phase while the load bank utilized was a three phase load system. The load bank utilized in this experiment had a balance load whose phase impedances were equal in magnitude and phase. The resistance value of the load bank is given in wattage (W). As the load was balanced in a three-phase load bank, conversion of three-phase loadinto the single phase load was done as in Equation 1: Pload 1Ø (1) 2.5. Development of Load Control Algorithm Software Development of a load control algorithm system is divided into two, which are software design, that acts as a brain to the load control algorithm, and hardware implementation, that demonstrates the effectiveness of the load algorithm. The algorithm flow chart is developed as guidance to the software development. Figure 3 below shows the algorithm flow chart developed for this load control system. The algorithm flowchart in Figure 3 starts with the measurement of the current from PV inveter and the load system. The algorithm program is developed to activate subject to the PV energy availability and will be placed to off immediately once the PV energy has diminished. Then, the PV current is compared to the load current. If the PV current is higher than the load current and meets the time delay set at respective
  • 4. IJECE ISSN: 2088-8708  Development of Load Control Algorithm for PV Microgrid (Mohamad Haireen Bin Fatheli) 622 individual load, the load will be connected sequentially. However, if the PV current is lower than the current load in turn, the algorithm flow chart will measure the difference between the load current and the PV current, respectively. The difference of the value is then compared with the threshold value. If the difference current is greater than the threshold value given, load will be shed accordingly, or else the amount of the load will be retained as it has been connected. The algorithm is a continuous process as long as PV energy is present. LABVIEW software is incorporated with the Data Acquisition (DAQ) devices to measure the current and voltages of the PV and load system. Figure 3. Algorithm flow chart for load control system A single channel configuration with a complete load control algorithm system for the experimental setup is shown in Figure 4. DAQ Assistant is utilized as a single simulated device to measure three parameters in the live system, namely, PCC Voltage, PV current and load current, respectively. Select Signals VI is employed in this software configuration to split up the three parameters measured using a single DAQ Assistant.
  • 5.  ISSN:2088-8708 IJECE Vol. 7, No. 2, April 2017 : 619–630 623 Figure 4. Single channel of load control algorithm system The hardware devices for load control algorithm system are listed in Table 1, which include the Point of Common Coupling (PCC) with the circuit breakers protection, isolation transformer, low voltage (LV) step-down transformer, transducer, relay switching modules, National Instrument Data Acquisition (NI DAQ), DC-DC converter, Buffer circuit, and LABVIEW programming,which all form a complete load control algorithm system. Figure 5 shows the load control algorithm block diagram established for this project. Table 1. Hardware components for load control algorithm system No. Hardware components Rating/Model Quantity 1 Isolation Transformer 240/240 V 1 2 LV step down transformer 240/6 V 1 3 Current Transducer 15 V, 20 A, LEM HY 20-P 2 4 Relay Switching Module 5V, 8-channel Relay Interface Board, 15-20mA Driver Current 2 5 Relay Switching Module 5V, 4-channel Relay Interface Board, 15-20mA Driver Current 1 6 NI compact DAQ Ethernet chassis NI 9181 4 7 Digital Output Module NI 9472 3 8 Analog Voltage Input Module NI 9205 1 9 NI Managed Ethernet Switch NI – MES 3980 1 10 Buffer Circuit 20 x1kΩ resistance circuit 1 11 DC-DC Converter 1A, 12/5 V 1 12 AC/DC Enclosed Switching Dual Power Supply 10A, 240Vac/12Vdc 1
  • 6. IJECE ISSN: 2088-8708  Development of Load Control Algorithm for PV Microgrid (Mohamad Haireen Bin Fatheli) 624 Figure 5. Load control algorithm block diagram 2.5.1. LABVIEW Software Load Control Algorithm In this experiment, LABVIEW software was incorporated with the Data Acquisition (DAQ) devices to measure the currents and voltages of the PV and load system. The measured parameters data were then transferred to the control application design in the LABVIEW code, to process the inputs following the designated algorithm software and generate digital output signals to trigger the relay function of a load control system. LABVIEW software has two panel architectures, namely the front panel and the block diagram panel. The front panel serves to define the algorithm interface, which in this experiment functioned to monitor the software interface and measured parameters. Figure 6 shows the front panel of the LABVIEW software. Figure 6. Front panel of LABVIEW software 2.6. Experimental Setup The actual experimental was carried out by configuring the PV inverter system operating in the islanding mode. To ensure the transition of the grid connected to the islanding mode be successful, a load bank was utilized to match the output generated by the PV system, while waiting the load algorithm system to initiate. Otherwise, the transition would not be successful while conducting experiment at the peak output
  • 7.  ISSN:2088-8708 IJECE Vol. 7, No. 2, April 2017 : 619–630 625 of the PV system. Figure 7 shows the hardware experimental setup. The novelty of this experimental setup is that the configuration allows the grid-tie inverter to operate in islanding mode with the source of reference voltage. For simplicity, we considered the utility as the reference voltage, which can be replaced by other tupes of AC power source. Figure 7. Hardware experimental setup 3. RESULTS AND ANALYSIS 3.1. Intentional - Islanding With the Load Control Algorithm System The load control algorithm is a designated system that controls the amount of the load to be connected corresponding to the PV generation level. The load control algorithm system monitors the magnitude of current delivered to the load, and controls the energy balance between the PV generation and load demand respectively. 3.1.1. Load Demand Follow the PV Generation PV inverter current and load current are two parameters which were monitored and controlled in this algorithm design. The load current was designed to follow the PV current, as shown in Figure 8. Load demand parallel with generation was successfully established in the actual system test operating in islanding mode, producing load current corresponding to PV current change. The algorithm design managed to control the load amount according to the PV generation level by controlling the load current which continuously followed the PV current all the time. However, at certain operation cycle, it was found that the load current encountered fluctuation for a few seconds before resuming normal operation. Fluctuations occurred due to the hardware timing of data acquisition (DAQ) that was not synchronized with the software timing. Never the less, the fluctuation could be minimized by introducing time delay to the software program. As a result of the mismatch of the software and hardware timing, fluctuation occurred since the relay switching module was supplied with intermittent signal from the DAQ modules. Furthermore, the DAQ modules permitted the relay operation to intermittently operate until the mismatch between the software and hardware timing was rectified through self synchronization on these two timings accordingly. The load current was higher in the graph presented, as a sign to prevent reverse current from propagating into the external voltage source. The load was slightly higher from the PV current designed in the algorithm as a security assurance to prevent reverse power flow from occurring. Regardless of the intermittent of the PV supply, the load could be controlled for the amount of the PV supply generated. Unlike microgrid PV panel Grid-tie Inverter Distribution Board Point of Commo n Coupling (PCC) Isolation Transformer TNB single phase supply LABVIEW monitoring and controlling Load control Algorithm Bulbs Load Load Bank
  • 8. IJECE ISSN: 2088-8708  Development of Load Control Algorithm for PV Microgrid (Mohamad Haireen Bin Fatheli) 626 experimental setup using solar power emulator [11], actual working PV system with real connected loads was considered in this work. Figure 8. Load current follow PV current generation 3.1.2. Voltage Stability Offered by Load Control System Figure 9 shows the load voltage measured in islanding mode with the load control algorithm system. The voltage can be briefly described as with the load control system, the load voltage was observed operating in +10%, -6% voltage limit [12] and free from any voltage violation in islanding. Figure 9. Load voltage operating in islanding with load control system Figure 10 shows irradiance as a variable parameter. The fluctuation of irradiance energy was due to the weather and global sun position, which implies that the PV source is not a constant type of energy, thus posing reliability issues in power generation [13]. The irradiance energy was then transformed into DC input of the PV inverter, where the energy conversion output was in AC waveform, as shown in Figure 11. The AC voltage declined excessively at the beginning of the operational cycle because the transition from grid was disconnected to the islanding mode. Nevertheless, the DC voltage could be kept constant, mainly due to the Maximum Power Point Tracking (MPPT) that maximized the power output in event of irradiance fluctuation. The AC voltage successfully controlled working at voltage limit, free from any voltage violence. In spite of fluctuation due to weather variances affecting the input PV inverter, which was unmanageable by the MPPT, the voltage could still be retained as constant due to the aids of the load control algorithm system. Hence, the PV inverter current source proves fit to workin islanding environment. Fluctuation due to mismatch of hardware and software timing
  • 9.  ISSN:2088-8708 IJECE Vol. 7, No. 2, April 2017 : 619–630 627 Figure 10. Irradiance data Figure 11. DC and AC voltage PV inverter system 3.1.3. Frequency Stability Offered by Load Control System Figure 12 shows the load frequency showing with the load control algorithm system, in which frequency was operated in limit from 49.5Hz to 50.5Hz [14] and immune from any gradual changes in the course of unreliable source provided by the PV system in islanding. Figure 12. Load frequency measured Transition from grid disconnected to island mode
  • 10. IJECE ISSN: 2088-8708  Development of Load Control Algorithm for PV Microgrid (Mohamad Haireen Bin Fatheli) 628 3.2. PV Inverter Current Distortion The measured PV inverter current and the load current are shown in Figure 13. It was observed that the inverter current waveform was in a form of distorted signal, while the load current waveform was purely in sinusoidal from. The degree of distortion was due to the harmonic presence, showed when significant distorted signal was encountered and when low PV supply was generated to the load. At this time, the PV inverter operated with low power conversion where the distortion was very high [15] [16]. The external voltage source in turn, provided the necessary current that mixed up with the distorted current from the PV inverter, producing pure sinusoidal waveform to the load. Thus, power quality was preserved in good quality to the load. Figure 13. PV inverter current and load current Figure 14 shows the irradiance data against temperature, showing that distorted signal appeared at low irradiance, proportional to the low panel temperature. The relation shows that when temperature rises, the irradiance will rise as well [17]. As such, the inverter would have problems producing good power quality if it had worked as a standalone system. The function of external voltage in this experiment was to ensure good power quality be delivered to the load, providing compensation to the distorted signal at the time of the irradiance energy being low. Figure 14. Irradiance versus temperature The results showed that the load current followed the PV current continuously all the time until the PV supply was dismissed. The voltage was constantly stable at the point of PCC, as the load was connected based on the PV generation level, which prevented any over-voltage or under-voltage scenario from
  • 11.  ISSN:2088-8708 IJECE Vol. 7, No. 2, April 2017 : 619–630 629 occurring. Hence, the load control algorithm system, instead of addressing the stability issue in the intentional islanding from the context of voltage and frequency, also provided protection from over-voltage or under-voltage to the load and PV supply at the same time. It has been proven that the load control algorithm system can effectively control the load in actual test of grid connected PV system for PV microgrid restoration, which is in line with the objective of this paper. 4. CONCLUSION Variability of solar irradiance due to weather condition could result in the mismatch between solar PV generation and demand, particularly in the microgrid context. This may lead to detrimental effects of over/under voltage or over/under frequency. As proven in this study, the developed load control algorithm is able to accommodate PV generation operating in intentional-islanding mode. The load control algorithm system will maintain demand-supply in a balance condition, by usinga switch relay control that connects the loads according to the PV generation level. The load control algorithm system has been successfully designed using LABVIEW software to form a complete and autonomous load control algorithm system to control the load presence in accordance to the PV generation. ACKNOWLEDGEMENTS The authors gratefully acknowledge the financial support provided by the Ministry of Higher Education Malaysia under the Research Grant: RAGS/1/2015/TK03/FKE/03/B00096. Special appreciation and gratitude are expressed to the Center of Robotics and Industrial Automation (CeRIA), Centre of Research and Innovation Management (CRIM) and Faculty of Electrical Engineering (FKE) ofUTeM for giving the financial and moral support forsuccessful completion of this project. REFERENCES [1] Barnes, M., Dimeas, A., Engler, A., Fitzer, C., Hatziargryriou, N., Papathanassiou, S., Vandenbergh, M., 2005, “Microgrid laboratory facilities”, International Conference on Future Power Systems, pp. 1–6. [2] Trujillio Rodriguez, C., Velasco de la Fuente, D., Garcera, G., Figueres, E., Guacaneme Moreno, J.A., 2013, “Reconfigurable Control Scheme for a PV Microinverter Working in Both Grid-Connected and Island Modes”, IEEE Transactions on Industrial Electronics, 60(4), pp 1582-1595. [3] Dall’Anese, E., and Gianakis, G.B., 2014, “Risk-Constrained Microgrid Reconfiguration Using Group Sparsity”, IEEE Transactions on Sustainable Energy, 5(4), pp. 1415-1425. [4] Hartono, B.S., Budiyanto, Y., Setiabudy, R., 2013, “Review of Microgrid Technology”, International Conference on QiR (Quality in Research), pp. 127-132. [5] IEEE.Standards-1547.2, 2008. IEEE Application Guide for IEEE STD 1547TM, IEEE Standard for Interconnecting Distributed Resources with Electric Power Systems. IEEE Standards Coordinating Committee 21. [Online] Available from: http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4816078 [Accessed: 12 December 2014]. [6] Wandhare, R.G., Thale, S., Agarwal, V., 2014, “Design of Photovoltaic Power Conditioning System for Hierarchical Control of a Microgri”, IEEE 40th Photovoltaic Specialist Conference (PVSC), pp 3144-3149. [7] M. Shamshiri, C. K. Gan and Chee Wei Tan, "A review of recent development in smart grid and micro-grid laboratories," Power Engineering and Optimization Conference (PEOCO) Melaka, Malaysia, 2012 IEEE International, Melaka, 2012, pp. 367-372. [8] Guo, Xiao-Qiang., Wu, Wei-Yang., Gu, He-Rong., 2011, “Phase Locked Loop and Synchronization Methods for Grid-Interfaced Converters: A Review”, [Online] Available at: www.red.pe.org.pl/articles/2011/4/48.pdf [Accessed on 12 February 2014] [9] Kotsopoulos, A., Duarte, J.L., Hendrix, M.A.M., Heskes, P.J.M., 2002, “Islanding behaviour of grid connected PV inverters operating under different control schemes”, IEEE 33rd Power Electronics Specialists Conference, 2002, 2002(3), pp. 1506-1511. [10] ALLEN-BRADLEY-CB. Application, 1994. Using Circuit Breakers to Protect Transformer Circuits. ALLEN- BRADLEY. [11] R.R. Islam, M. Liao, T.H. Vo and J. Ravishankar, "Experimental setup of a microgrid with wind and solar power emulators," Electrical Energy Systems (ICEES), 2014 IEEE 2nd International Conference on, Chennai, 2014, pp. 9- 14. [12] Tenaga Nasional Berhad, “Electricity Supply Application Handbook”, 3rd ed. 2011. [Online] https://www.tnb.com.my/assets/files/ESAHv3.pdf] [13] Afroze, S., Udaykumar, R.Y., Naik, A., 2012, “A Systematic Approach to Grid Connected PV system”, IEEE 5th Power India Conference, pp. 1-5. [14] Johari, A., 2010. The Malaysian Grid Code. [Online]. 2010. Available from: http://www.tnb.com.my/tnb/application/uploads/uploaded/the Malaysian grid code.pdf.
  • 12. IJECE ISSN: 2088-8708  Development of Load Control Algorithm for PV Microgrid (Mohamad Haireen Bin Fatheli) 630 [15] Hamid, M.I., and Jusoh, A., 2014, “Reduction of Waveform Distortion in Grid-Injection Current from Single Phase Utility Interactive PV-Inverter”, Energy Conversion and Management, pp. 212-226. [16] M. Ayub, C.K. Gan and A.F.A. Kadir, "The impact of grid-connected PV systems on Harmonic Distortion," 2014 IEEE Innovative Smart Grid Technologies - Asia (ISGT ASIA), Kuala Lumpur, 2014, pp. 669-674. [17] Anonymous, 2010, “Coordinated Control Scheme for Standalone PV System with Nonlinear Load”, IEEE PES Transmission and Distribution Conference and Exposition, pp. 1-8. [18] M. Abdulkadir, A.S. Samosir, A.H.M. Yatim, 2013, “Modeling and Simulation of Solar Photovoltaic System, Its Dynamics and Transient Characteristics in LABVIEW”, International Journal of Power Electronics and Drive System (IJPEDS), pp. 185-192. [19] Himanshu Sharma, Nitai Pal, Yaduvir Singh, Pradip Kumar Sadhu, 2015, “Development nd Simulation of Stand Alone Photovoltaic Model Using Matlab/Simulink”, International Journal of Power Electronics and Drive System (IJPEDS), Vol.6, No. 4, pp. 703-711. [20] Yafaoui, A., Bin Wu, Kouro, S., 2012, “Improved Active Frequency Drift Anti-islanding Detection Method for Grid Connected Photovoltaic Systems”, IEEE Transactions on Power Electronics, 27(5), pp. 2367-2375. [21] Xin Chen., Yan Hong Wan., Yun Cheng Wang., 2013, “A Novel Seamless Transferring Control Method for Microgrid Based on Master-Slave Configuration.”,2013 IEEE ECCE Asia Downunder (ECCE Asia) 2013, pp. 351-357. [22] Liu Jie, Yang Haizhu, 2009, “Anti-Islanding Control of Grid Connected Photovoltaic Inverter Based on Positive Feedback Frequency Drift”, IEEE 6th International Power Electronics and Motion Control Conference, pp. 2147-2150.