Jahangir Hossain - Academia.edu (original) (raw)

Papers by Jahangir Hossain

2019 IEEE PES GTD Grand International Conference and Exposition Asia (GTD Asia)

With the increasing penetration of photo-voltaic (PV) units into electrical grids, particularly i... more With the increasing penetration of photo-voltaic (PV) units into electrical grids, particularly in distribution networks (DNs), the concern of short-term voltage instability (STVI) are growing in the presence of induction motor (IM) loads. On the event of unsymmetrical faults, STVI issues could be more complicated as the next-generation PV systems would require negative sequence power injection into the grid in conjunction with positive one. Therefore, this paper comprehensively investigates the impact of negative sequence power on the shortterm voltage stability (STVS) of DNs. The method of characterizing an unbalanced fault and supplementary controls for PV systems are developed. Different case studies are conducted on a balanced IEEE 4 bus and an unbalanced IEEE 13 bus system by injecting different level of negative sequence power considering with and without peak current limitation of the PV converters. It is observed that STVS is likely to be weakened in case of large negative sequence power penetration, while injecting high positive sequence power can cause excessive voltage swell resulting inverter disconnections. Therefore, both positive and negative sequence powers need to be injected optimally to ensure the system's security following a fault.

2012 IEEE Power and Energy Society General Meeting, 2012

This paper proposes an effective VAR planning based on reactive power margin for the enhancement ... more This paper proposes an effective VAR planning based on reactive power margin for the enhancement of dynamic voltage stability in distribution networks with distributed wind generation. The analysis is carried over a distribution test system representative of the Kumamoto area in Japan. The detailed mathematical modeling of the system is also presented. Firstly, this paper provides simulation results showing the effects of composite load on voltage dynamics in the distribution network through an accurate time-domain analysis. Then, a cost-effective combination of shunt capacitor bank and distribution static synchronous compensator (D-STATCOM) is selected to ensure fast voltage recovery after a sudden disturbance. The analysis shows that the proposed approach can reduce the size of compensating devices, which in turn, reduces the cost. It also reduces power loss of the system.

2013 IEEE 8th Conference on Industrial Electronics and Applications (ICIEA), 2013

Photovoltaic (PV) units along with other distributed energy resources (DERs) are located close to... more Photovoltaic (PV) units along with other distributed energy resources (DERs) are located close to each other in distributed systems and they are equipped with different controllers. In such systems each manipulated variable may affect several controlled variables causing interaction between the input/output loops and degrade the dynamic performance of the system. This paper presents several case studies to quantify the degree of interaction and identify proper input output signals to minimize the impact of negative interaction. A robust control is also designed with the proper input output signals to alleviate these interactions and enhance the dynamic performance. It is found that negative dynamic interaction can adversely affect the performance of the distribution system and the designed controller can improve the performance by minimizing the negative interactions.

2018 Australasian Universities Power Engineering Conference (AUPEC), 2018

This paper proposes a novel approach of distributed coordination control for multiple sub-microgr... more This paper proposes a novel approach of distributed coordination control for multiple sub-microgrids (SMGs) within a hybrid AC/DC microgrid. The conventional control approach for managing power flow among AC and DC SMGs is based on the proportional power sharing principle. This is mainly implemented by equalising the normalized voltage at the DC side and the frequency at the AC side for any interfaced SMGs. The proposed method suggests a distributed control system that ensures a total controllability for the interlinking converters. It overcomes the total dependency on a specific variable for power exchange. The proposed method not only enables control of the power flow between SMGs but also ensures the continuity of power transfer if any single SMG fails. Three case studies are presented to demonstrate the validity and capability of the proposed approach using the MATLAB/Simulink software. From the obtained results, it is found that the proposed control system provides a high level...

IEEE Systems Journal, 2020

The increasing penetration of distributed generations (DGs) and electric vehicles (EVs) offers no... more The increasing penetration of distributed generations (DGs) and electric vehicles (EVs) offers not only several opportunities but also introduces many challenges for the distribution system operators (DSOs) regarding power quality. This article investigates the network performances due to uncoordinated DG and EV distribution. It also considers power quality-related performances such as the neutral current, energy loss, voltage imbalance, and bus voltage as a multiobjective optimization problem. The differential evolution optimization algorithm is employed to solve the multiobjective optimization problem to coordinate EV and DG in a distribution grid. This article proposed a method to coordinate EV and DG distribution. The proposed method allows DSOs to jointly optimize the phase sequence and optimal dispatch of DGs to improve the network's performance. If the network requires further improvement, the EV charging or discharging rate is coordinated for a particular location. The efficacy of the proposed method is tested in an Australian low-voltage distribution grid considering the amount of imbalance due to higher penetration of DG and EV. It is observed that the proposed method reduces voltage unbalance factor by up to 98.24%, neutral current up to 94%, and energy loss by 59.45%, and improve bus voltage by 10.42%. Index Terms-Compensating neutral current, coordinated/ uncoordinated charging, distributed generation (DG) dispatch, electric vehicle (EV), mitigating voltage unbalance. Md. Rabiul Islam (Student Member, IEEE) received the M.Sc. degree in renewable energy from the University of Oldenburg, Oldenburg, Germany, in 2015, and the B.Sc. degree in electrical and electronic engineering from the

IEEE Transactions on Industrial Informatics, 2019

Powering small islands with reliable, affordable and green electricity is a big challenge due to ... more Powering small islands with reliable, affordable and green electricity is a big challenge due to their dispersed geographical location with limited number of consumers and the heavy dependence on fossil fuels. This paper aims to address this challenge of reducing dependency on fossil fuel generators by providing an easy and feasible solution using available and accessible energy resources. The proposed method utilizes the bidirectional energy transfer mechanism available in electric boats to support the consumers' power demand. It proposes a new realtime load-support (RTLS) system with a coordinated control using electric boats (EBs), community generators and battery energystorage systems. It analyzes the management of the intermittent sources-dependent small-scale grid in real time, under various weather, load, and battery state-of-charge conditions. The RTLS system coordinates the customers' load demand with the available EBs, photovoltaics (PVs) and battery storage to provide efficient load support and to regulate the bus voltage and frequency. The efficacy of the proposed system is validated both computationally in a real network and in a laboratory setup. It is found that this novel system can substantially reduce the grid load demand and maintain the power quality under various load/source uncertainties and fault conditions. The system robustness is also evaluated considering undesirable conditions, such as severe threephase faults and sudden EB disconnections. The performance of the proposed method is compared with that of the day-ahead loadmanagement approach to validate its effectiveness under various scenarios.

IEEE Transactions on Industrial Informatics, 2019

An improved vehicle-to-microgrid (V2M) framework is proposed for a commercial locality operating ... more An improved vehicle-to-microgrid (V2M) framework is proposed for a commercial locality operating as a hybrid alternating-current (AC) / direct-current (DC) microgrid, which optimally coordinates electric-vehicle (EV) storages in a distributed manner. An aggregator model is proposed that solves the economic dispatch problem of parked EV storages in a centralized fashion and generates power references in real-time for the designed EV storage controllers. Unlike the conventional EV storage controller, the proposed optimizationincorporated distributed EV storage controller (ODC) can switch from decentralized to distributed control mode or vice versa based on situations and utilizes a sparse vehicle-to-vehicle (V2V) communication network.The power flow between the AC and DC subgrids is managed by interlinking converters (IC). The IC control structure is augmented by combining voltage-and powerbased droop-control schemes in the power control loop. This modification enables simultaneous AC and DC bus voltage regulations. Case studies are carried out to validate the efficacy of the developed framework with a real commercial network and loads. The results exhibit robust performance of the overall system for generation-demand variability, transitions between islanded and grid-tied conditions, and user-preferred EV disconnections and time delay. Index Terms-Hybrid AC/DC microgrid, economic dispatch, interlinking inverter, electric vehicles, distributed cooperative control.

IEEE Transactions on Industrial Informatics, 2019

Contrary to reliability analysis in power systems with the main mission on safely and securely wi... more Contrary to reliability analysis in power systems with the main mission on safely and securely withstanding credible contingencies in day-today operations, resilience assessments are centered on high-impact low probability (HILP) events in the grid. This paper proposes an autonomous load restoration architecture founded on IEC 61850-8-1 GOOSE communication protocol to engender an enhanced feeder-level resilience in active power distribution grids. Different from the past research on outage management solutions, most of which (a) are not resilience-driven, (b) are reactive solutions to local single-fault events, and (c) do not address both network built-in flexibilities and flexible resources, the proposed solution harnesses (a) the imported power and flexibility from the neighboring networks, (b) Distributed Energy Resources (DERs), and (c) vehicle to grid (V2G) capacity of Electric Vehicles (EVs) aggregations to enhance the feeder-level resourcefulness for agile response and recovery. Through real-time self-reconfiguration strategies, the suggested solution is capable of coping both single and subsequent outage events, and will engender a heightened resilience before and during the contingency period. Moreover, a resilience evaluation framework, which quantifies the contribution of all resources involved in service restoration, is developed. Real-time performance of the designed architecture is evaluated on a realworld power distribution grid using a real-time Hardware-in-the-Loop (HIL) platform. Numerical case studies through a number of diverse scenarios demonstrate the efficacy of the proposed restoration solution in practicing an enhanced resilience in power distribution systems in response to HILP scenarios.

IET Smart Grid, 2019

Energy sharing through a microgrid (MG) is essential for islanded communities to maximise the use... more Energy sharing through a microgrid (MG) is essential for islanded communities to maximise the use of distributed energy resources (DERs) and battery energy storage systems (BESSs). Proper energy management and control strategies of such MGs can offer revenue to prosumers (active consumers with DERs) by routing excess energy to their neighbours and maintaining grid constraints at the same time. This paper proposes an advanced power-routing framework for a solarphotovoltaic (PV)-based islanded MG with a central storage system (CSS). An optimisation-based economic operation for the MG is developed that determines the power routing and energy sharing in the MG in the day-ahead stage. A modified droop controller-based real-time control strategy has been established that maintains the voltage constraints of the MG. The proposed power-routing framework is verified via a case study for a typical islanded MG. The outcome of the optimal economic operation and a controller verification of the proposed framework are presented to demonstrate the effectiveness of the proposed powerrouting framework. Results reveal that the proposed framework performs a stable control operation and provides a profit of 57 AU$/day at optimal conditions.

IEEE Transactions on Sustainable Energy, 2018

Short-term voltage instability (STVI) imposes a severe threat to modern distribution networks (DN... more Short-term voltage instability (STVI) imposes a severe threat to modern distribution networks (DNs) where a large number of intermittent distributed generator (DG) units, like rooftop photovoltaic (PV), is being integrated. Consequently, most of the international standards have been revised by incorporating the requirement of dynamic voltage support (DVS) through DG units, which is a promising approach to alleviate the STVI. In this paper, a novel DVS strategy is proposed to improve the short-term voltage stability (STVS) in residential grids. In comparison with other DVS strategies, the proposed DVS scheme maximizes the active power support from PV units following a contingency utilizing maximum allowable current of the PV inverters. Moreover, the inverter design margin is taken into account in designing the proposed scheme to limit the injected grid current within maximum allowable inverter current. The impact of inverter design margin on the STVS is explained, and the effectiveness of the proposed strategy compared with conventional DVS is demonstrated. The feasibility of the DVS control strategies in practical application is studied. Several case studies are carried out on benchmark IEEE 4 bus and IEEE 13 node test feeder systems, and finally on a ring-type DN. The results show that the proposed DVS scheme is feasible, and achieved superior performance compared to the other strategies. Furthermore, it has been shown that implementation of the proposed DVS scheme can avoid the installation of an expensive 1200 kVA D-STATCOM for STVS improvement in the target system.

IEEE Transactions on Power Electronics, 2018

This paper presents a fast and robust dc-bus voltage control method for single-phase grid-connect... more This paper presents a fast and robust dc-bus voltage control method for single-phase grid-connected dc/ac converters. The proposed technique precisely estimates the double-frequency (2-f) ripple of a dc-bus voltage and removes it from the voltagecontrol loop without adding any additional dynamics or oscillations. Conventionally, the 2-f ripple is managed by using large capacitors which increase the cost and bulkiness of a converter. As a state-of-the-art approach, a notch filter (NF) or a dc-voltage estimator is used to effectively block the 2-f ripple from the voltage-control loop, which can significantly reduce the capacitor size. However, such an approach introduces new dynamics in the control loop, causes additional oscillations on the bus voltage and increases the settling time of its response. This limits the degrees of freedom of the design to improve the overall system damping. The proposed method in this paper has no adverse impact on the original bus-voltage dynamic response. As a result, the bus-voltage control can be designed with higher speed and robustness and the whole system can operate with a reduced transient at both the bus voltage and the output ac current. The proposed approach is thoroughly analyzed and its effectiveness is validated through simulations and experimental results.

Applied Energy, 2018

Designing a feasible unified control system for a multifunctional on-board EV charger. • The EV c... more Designing a feasible unified control system for a multifunctional on-board EV charger. • The EV charger can operate in V2G/G2V mode as its main function. • The EV charger can simultaneously perform three ancillary functions of a STATCOM and an APF. • Stress on the EV battery is reduced using a two-leg buck-boost DC/DC converter. • Simulation and experimental results verify the efficacy of the proposed system.

Energies, 2018

In this paper, an Internet of Things (IoT) platform is proposed for Multi-Microgrid (MMG) system ... more In this paper, an Internet of Things (IoT) platform is proposed for Multi-Microgrid (MMG) system to improve unbalance compensation functionality employing three-phase four-leg (3P-4L) voltage source inverters (VSIs). The two level communication system connects the MMG system, implemented in Power System Computer Aided Design (PSCAD), to the cloud server. The local communication level utilizes Modbus Transmission Control Protocol/Internet Protocol (TCP/IP) and Message Queuing Telemetry Transport (MQTT) is used as the protocol for global communication level. A communication operation algorithm is developed to manage the communication operation under various communication failure scenarios. To test the communication system, it is implemented on an experimental testbed to investigate its functionality for MMG neutral current compensation (NCC). To compensate the neutral current in MMG, a dynamic NCC algorithm is proposed, which enables the MGs to further improve the NCC by sharing their...

Although microgrids facilitate the increased penetration of distributed generations (DGs) and imp... more Although microgrids facilitate the increased penetration of distributed generations (DGs) and improve the security of power supplies, they have some issues that need to be better understood and addressed before realising the full potential of microgrids. This paper presents a comprehensive list of challenges and opportunities supported by a literature review on the evolution of converter-based microgrids. The discussion in this paper presented with a view to establishing microgrids as distinct from the existing distribution systems. This is accomplished by, firstly, describing the challenges and benefits of using DG units in a distribution network and then those of microgrid ones. Also, the definitions, classifications and characteristics of microgrids are revised according to their specific roles to provide a sound basis for novice researchers to undertake ongoing research on microgrids.

Energies, 2017

Distributed generation (DG) is one of the key components of the emerging microgrid concept that e... more Distributed generation (DG) is one of the key components of the emerging microgrid concept that enables renewable energy integration in a distribution network. In DG unit operation, inverters play a vital role in interfacing energy sources with the grid utility. An effective interfacing can successfully be accomplished by operating inverters with effective control techniques. This paper reviews and categorises different control methods (voltage and primary) for improving microgrid power quality, stability and power sharing approaches. In addition, the specific characteristics of microgrids are summarised to distinguish from distribution network control. Moreover, various control approaches including inner-loop controls and primary controls are compared according to their relative advantages and disadvantages. Finally, future research trends for microgrid control are discussed pointing out the research opportunities. This review paper will be a good basis for researchers working in microgrids and for industry to implement the ongoing research improvement in real systems.

2016 Australasian Universities Power Engineering Conference (AUPEC), 2016

Recently transformerless grid-tied photovoltaic (PV) inverters are getting popular in order to ad... more Recently transformerless grid-tied photovoltaic (PV) inverters are getting popular in order to address several concerns; for example, poor efficiency, large size, and heavy weight compared to those with traditional inverter topologies. However, according to the several recently updated grid codes, the grid-tied PV inverter are required to provide full range of services such as maximum power injection, grid voltage regulation (VR), and fault ride through (FRT). In this paper, the performance of a transformerless PV system with a new droop based controller connected to the low voltage distribution system under different operating condition is investigated. In order to provide full-range of grid supporting services, three operation modes are proposed. A detail description of the transformerless PV inverter, droop based controller, and the control strategy are provided. The theoretical analysis is verified using nonlinear simulations in MATLAB/Simulink software environment. The results show that the presented system is capable of injecting maximum power when participate in the grid voltage regulation, and also can enhance fault ride through capability.

IEEE Journal of Photovoltaics, 2014

ABSTRACT This paper presents a robust stabilization scheme for a three-phase grid-connected photo... more ABSTRACT This paper presents a robust stabilization scheme for a three-phase grid-connected photovoltaic system to control the current injected into the grid and dc-link voltage to extract maximum power from photovoltaic (PV) units. The scheme is mainly based on the design of a robust controller using a partial feedback linearizing approach of feedback linearization, where the robustness of the proposed scheme is ensured by considering uncertainties within the PV system model. In this paper, the uncertainties are modeled as structured uncertainties based on the satisfaction of matching conditions. The performance of the proposed stabilization scheme is evaluated on a three-phase grid-connected PV system in terms of delivering maximum power under changes in atmospheric conditions.

2014 Australasian Universities Power Engineering Conference (AUPEC), 2014

Voltage and frequency regulations are main requirements for autonomous operation of an isolated m... more Voltage and frequency regulations are main requirements for autonomous operation of an isolated microgrid with electronically interfaced distributed energy resource (DER) units. This paper presents a robust decentralized control design scheme for a multi-DER microgrid to enhance its voltage and frequency regulations. The proposed control scheme utilizes linear quadratic (LQ) decentralized control scheme to design controllers, which are robust to the uncertainty in the network and system nonlinearities. The effectiveness of the proposed controller is demonstrated through simulation on a test system, with complete nonlinear models, for large disturbances. It is found that the designed controller provides excellent performance during transient periods as well as restores the pre-disturbance steady-state operation within prescribed time frame.

Global Sustainable Development and Renewable Energy Systems

This chapter presents an overview Photovoltaic (PV) power generation and integration of PV system... more This chapter presents an overview Photovoltaic (PV) power generation and integration of PV systems with power grid. This chapter also presents a Feedback Linearizing Current Controller (FBLCC) to synchronize the PV system with the grid. This controller is designed based on the feedback linearization technique. The reference current for the controller is generated from the Maximum Power Point Tracker (MPPT). The stability of a single-phase grid connected PV system is analyzed through the Lyapunov function. To do these things, a suitable mathematical model of grid-connected PV system is also presented in this chapter. The performance of the designed controller is tested on a single-phase grid-connected PV system.

IEEE Systems Journal, 2012

The complexity of power systems has increased in recent years due to the operation of existing tr... more The complexity of power systems has increased in recent years due to the operation of existing transmission lines closer to their limits, using flexible AC transmission system devices (FACTS), and also due to the increased penetration of new types of generators that have more intermittent characteristics and lower inertial response, such as wind generators. This changing nature of a power system has considerable effect on its dynamic behaviours resulting in power swings, dynamic interactions between different power system devices and less synchronized coupling. This paper presents some analyses of this changing nature of power systems and their dynamic behaviours to identify critical issues that limit the large-scale integration of wind generators and FACTS devices. In addition, this paper addresses some general concerns towards high compensations in different grid topologies. The studies in this paper are conducted on the New England and New York power system model under both small and large disturbances. From the analyses, it can be concluded that high compensation can reduce the security limits under certain operating conditions, and the modes related to operating slip and shaft stiffness are critical as they may limit the large-scale integration of wind generation.

2019 IEEE PES GTD Grand International Conference and Exposition Asia (GTD Asia)

With the increasing penetration of photo-voltaic (PV) units into electrical grids, particularly i... more With the increasing penetration of photo-voltaic (PV) units into electrical grids, particularly in distribution networks (DNs), the concern of short-term voltage instability (STVI) are growing in the presence of induction motor (IM) loads. On the event of unsymmetrical faults, STVI issues could be more complicated as the next-generation PV systems would require negative sequence power injection into the grid in conjunction with positive one. Therefore, this paper comprehensively investigates the impact of negative sequence power on the shortterm voltage stability (STVS) of DNs. The method of characterizing an unbalanced fault and supplementary controls for PV systems are developed. Different case studies are conducted on a balanced IEEE 4 bus and an unbalanced IEEE 13 bus system by injecting different level of negative sequence power considering with and without peak current limitation of the PV converters. It is observed that STVS is likely to be weakened in case of large negative sequence power penetration, while injecting high positive sequence power can cause excessive voltage swell resulting inverter disconnections. Therefore, both positive and negative sequence powers need to be injected optimally to ensure the system's security following a fault.

2012 IEEE Power and Energy Society General Meeting, 2012

This paper proposes an effective VAR planning based on reactive power margin for the enhancement ... more This paper proposes an effective VAR planning based on reactive power margin for the enhancement of dynamic voltage stability in distribution networks with distributed wind generation. The analysis is carried over a distribution test system representative of the Kumamoto area in Japan. The detailed mathematical modeling of the system is also presented. Firstly, this paper provides simulation results showing the effects of composite load on voltage dynamics in the distribution network through an accurate time-domain analysis. Then, a cost-effective combination of shunt capacitor bank and distribution static synchronous compensator (D-STATCOM) is selected to ensure fast voltage recovery after a sudden disturbance. The analysis shows that the proposed approach can reduce the size of compensating devices, which in turn, reduces the cost. It also reduces power loss of the system.

2013 IEEE 8th Conference on Industrial Electronics and Applications (ICIEA), 2013

Photovoltaic (PV) units along with other distributed energy resources (DERs) are located close to... more Photovoltaic (PV) units along with other distributed energy resources (DERs) are located close to each other in distributed systems and they are equipped with different controllers. In such systems each manipulated variable may affect several controlled variables causing interaction between the input/output loops and degrade the dynamic performance of the system. This paper presents several case studies to quantify the degree of interaction and identify proper input output signals to minimize the impact of negative interaction. A robust control is also designed with the proper input output signals to alleviate these interactions and enhance the dynamic performance. It is found that negative dynamic interaction can adversely affect the performance of the distribution system and the designed controller can improve the performance by minimizing the negative interactions.

2018 Australasian Universities Power Engineering Conference (AUPEC), 2018

This paper proposes a novel approach of distributed coordination control for multiple sub-microgr... more This paper proposes a novel approach of distributed coordination control for multiple sub-microgrids (SMGs) within a hybrid AC/DC microgrid. The conventional control approach for managing power flow among AC and DC SMGs is based on the proportional power sharing principle. This is mainly implemented by equalising the normalized voltage at the DC side and the frequency at the AC side for any interfaced SMGs. The proposed method suggests a distributed control system that ensures a total controllability for the interlinking converters. It overcomes the total dependency on a specific variable for power exchange. The proposed method not only enables control of the power flow between SMGs but also ensures the continuity of power transfer if any single SMG fails. Three case studies are presented to demonstrate the validity and capability of the proposed approach using the MATLAB/Simulink software. From the obtained results, it is found that the proposed control system provides a high level...

IEEE Systems Journal, 2020

The increasing penetration of distributed generations (DGs) and electric vehicles (EVs) offers no... more The increasing penetration of distributed generations (DGs) and electric vehicles (EVs) offers not only several opportunities but also introduces many challenges for the distribution system operators (DSOs) regarding power quality. This article investigates the network performances due to uncoordinated DG and EV distribution. It also considers power quality-related performances such as the neutral current, energy loss, voltage imbalance, and bus voltage as a multiobjective optimization problem. The differential evolution optimization algorithm is employed to solve the multiobjective optimization problem to coordinate EV and DG in a distribution grid. This article proposed a method to coordinate EV and DG distribution. The proposed method allows DSOs to jointly optimize the phase sequence and optimal dispatch of DGs to improve the network's performance. If the network requires further improvement, the EV charging or discharging rate is coordinated for a particular location. The efficacy of the proposed method is tested in an Australian low-voltage distribution grid considering the amount of imbalance due to higher penetration of DG and EV. It is observed that the proposed method reduces voltage unbalance factor by up to 98.24%, neutral current up to 94%, and energy loss by 59.45%, and improve bus voltage by 10.42%. Index Terms-Compensating neutral current, coordinated/ uncoordinated charging, distributed generation (DG) dispatch, electric vehicle (EV), mitigating voltage unbalance. Md. Rabiul Islam (Student Member, IEEE) received the M.Sc. degree in renewable energy from the University of Oldenburg, Oldenburg, Germany, in 2015, and the B.Sc. degree in electrical and electronic engineering from the

IEEE Transactions on Industrial Informatics, 2019

Powering small islands with reliable, affordable and green electricity is a big challenge due to ... more Powering small islands with reliable, affordable and green electricity is a big challenge due to their dispersed geographical location with limited number of consumers and the heavy dependence on fossil fuels. This paper aims to address this challenge of reducing dependency on fossil fuel generators by providing an easy and feasible solution using available and accessible energy resources. The proposed method utilizes the bidirectional energy transfer mechanism available in electric boats to support the consumers' power demand. It proposes a new realtime load-support (RTLS) system with a coordinated control using electric boats (EBs), community generators and battery energystorage systems. It analyzes the management of the intermittent sources-dependent small-scale grid in real time, under various weather, load, and battery state-of-charge conditions. The RTLS system coordinates the customers' load demand with the available EBs, photovoltaics (PVs) and battery storage to provide efficient load support and to regulate the bus voltage and frequency. The efficacy of the proposed system is validated both computationally in a real network and in a laboratory setup. It is found that this novel system can substantially reduce the grid load demand and maintain the power quality under various load/source uncertainties and fault conditions. The system robustness is also evaluated considering undesirable conditions, such as severe threephase faults and sudden EB disconnections. The performance of the proposed method is compared with that of the day-ahead loadmanagement approach to validate its effectiveness under various scenarios.

IEEE Transactions on Industrial Informatics, 2019

An improved vehicle-to-microgrid (V2M) framework is proposed for a commercial locality operating ... more An improved vehicle-to-microgrid (V2M) framework is proposed for a commercial locality operating as a hybrid alternating-current (AC) / direct-current (DC) microgrid, which optimally coordinates electric-vehicle (EV) storages in a distributed manner. An aggregator model is proposed that solves the economic dispatch problem of parked EV storages in a centralized fashion and generates power references in real-time for the designed EV storage controllers. Unlike the conventional EV storage controller, the proposed optimizationincorporated distributed EV storage controller (ODC) can switch from decentralized to distributed control mode or vice versa based on situations and utilizes a sparse vehicle-to-vehicle (V2V) communication network.The power flow between the AC and DC subgrids is managed by interlinking converters (IC). The IC control structure is augmented by combining voltage-and powerbased droop-control schemes in the power control loop. This modification enables simultaneous AC and DC bus voltage regulations. Case studies are carried out to validate the efficacy of the developed framework with a real commercial network and loads. The results exhibit robust performance of the overall system for generation-demand variability, transitions between islanded and grid-tied conditions, and user-preferred EV disconnections and time delay. Index Terms-Hybrid AC/DC microgrid, economic dispatch, interlinking inverter, electric vehicles, distributed cooperative control.

IEEE Transactions on Industrial Informatics, 2019

Contrary to reliability analysis in power systems with the main mission on safely and securely wi... more Contrary to reliability analysis in power systems with the main mission on safely and securely withstanding credible contingencies in day-today operations, resilience assessments are centered on high-impact low probability (HILP) events in the grid. This paper proposes an autonomous load restoration architecture founded on IEC 61850-8-1 GOOSE communication protocol to engender an enhanced feeder-level resilience in active power distribution grids. Different from the past research on outage management solutions, most of which (a) are not resilience-driven, (b) are reactive solutions to local single-fault events, and (c) do not address both network built-in flexibilities and flexible resources, the proposed solution harnesses (a) the imported power and flexibility from the neighboring networks, (b) Distributed Energy Resources (DERs), and (c) vehicle to grid (V2G) capacity of Electric Vehicles (EVs) aggregations to enhance the feeder-level resourcefulness for agile response and recovery. Through real-time self-reconfiguration strategies, the suggested solution is capable of coping both single and subsequent outage events, and will engender a heightened resilience before and during the contingency period. Moreover, a resilience evaluation framework, which quantifies the contribution of all resources involved in service restoration, is developed. Real-time performance of the designed architecture is evaluated on a realworld power distribution grid using a real-time Hardware-in-the-Loop (HIL) platform. Numerical case studies through a number of diverse scenarios demonstrate the efficacy of the proposed restoration solution in practicing an enhanced resilience in power distribution systems in response to HILP scenarios.

IET Smart Grid, 2019

Energy sharing through a microgrid (MG) is essential for islanded communities to maximise the use... more Energy sharing through a microgrid (MG) is essential for islanded communities to maximise the use of distributed energy resources (DERs) and battery energy storage systems (BESSs). Proper energy management and control strategies of such MGs can offer revenue to prosumers (active consumers with DERs) by routing excess energy to their neighbours and maintaining grid constraints at the same time. This paper proposes an advanced power-routing framework for a solarphotovoltaic (PV)-based islanded MG with a central storage system (CSS). An optimisation-based economic operation for the MG is developed that determines the power routing and energy sharing in the MG in the day-ahead stage. A modified droop controller-based real-time control strategy has been established that maintains the voltage constraints of the MG. The proposed power-routing framework is verified via a case study for a typical islanded MG. The outcome of the optimal economic operation and a controller verification of the proposed framework are presented to demonstrate the effectiveness of the proposed powerrouting framework. Results reveal that the proposed framework performs a stable control operation and provides a profit of 57 AU$/day at optimal conditions.

IEEE Transactions on Sustainable Energy, 2018

Short-term voltage instability (STVI) imposes a severe threat to modern distribution networks (DN... more Short-term voltage instability (STVI) imposes a severe threat to modern distribution networks (DNs) where a large number of intermittent distributed generator (DG) units, like rooftop photovoltaic (PV), is being integrated. Consequently, most of the international standards have been revised by incorporating the requirement of dynamic voltage support (DVS) through DG units, which is a promising approach to alleviate the STVI. In this paper, a novel DVS strategy is proposed to improve the short-term voltage stability (STVS) in residential grids. In comparison with other DVS strategies, the proposed DVS scheme maximizes the active power support from PV units following a contingency utilizing maximum allowable current of the PV inverters. Moreover, the inverter design margin is taken into account in designing the proposed scheme to limit the injected grid current within maximum allowable inverter current. The impact of inverter design margin on the STVS is explained, and the effectiveness of the proposed strategy compared with conventional DVS is demonstrated. The feasibility of the DVS control strategies in practical application is studied. Several case studies are carried out on benchmark IEEE 4 bus and IEEE 13 node test feeder systems, and finally on a ring-type DN. The results show that the proposed DVS scheme is feasible, and achieved superior performance compared to the other strategies. Furthermore, it has been shown that implementation of the proposed DVS scheme can avoid the installation of an expensive 1200 kVA D-STATCOM for STVS improvement in the target system.

IEEE Transactions on Power Electronics, 2018

This paper presents a fast and robust dc-bus voltage control method for single-phase grid-connect... more This paper presents a fast and robust dc-bus voltage control method for single-phase grid-connected dc/ac converters. The proposed technique precisely estimates the double-frequency (2-f) ripple of a dc-bus voltage and removes it from the voltagecontrol loop without adding any additional dynamics or oscillations. Conventionally, the 2-f ripple is managed by using large capacitors which increase the cost and bulkiness of a converter. As a state-of-the-art approach, a notch filter (NF) or a dc-voltage estimator is used to effectively block the 2-f ripple from the voltage-control loop, which can significantly reduce the capacitor size. However, such an approach introduces new dynamics in the control loop, causes additional oscillations on the bus voltage and increases the settling time of its response. This limits the degrees of freedom of the design to improve the overall system damping. The proposed method in this paper has no adverse impact on the original bus-voltage dynamic response. As a result, the bus-voltage control can be designed with higher speed and robustness and the whole system can operate with a reduced transient at both the bus voltage and the output ac current. The proposed approach is thoroughly analyzed and its effectiveness is validated through simulations and experimental results.

Applied Energy, 2018

Designing a feasible unified control system for a multifunctional on-board EV charger. • The EV c... more Designing a feasible unified control system for a multifunctional on-board EV charger. • The EV charger can operate in V2G/G2V mode as its main function. • The EV charger can simultaneously perform three ancillary functions of a STATCOM and an APF. • Stress on the EV battery is reduced using a two-leg buck-boost DC/DC converter. • Simulation and experimental results verify the efficacy of the proposed system.

Energies, 2018

In this paper, an Internet of Things (IoT) platform is proposed for Multi-Microgrid (MMG) system ... more In this paper, an Internet of Things (IoT) platform is proposed for Multi-Microgrid (MMG) system to improve unbalance compensation functionality employing three-phase four-leg (3P-4L) voltage source inverters (VSIs). The two level communication system connects the MMG system, implemented in Power System Computer Aided Design (PSCAD), to the cloud server. The local communication level utilizes Modbus Transmission Control Protocol/Internet Protocol (TCP/IP) and Message Queuing Telemetry Transport (MQTT) is used as the protocol for global communication level. A communication operation algorithm is developed to manage the communication operation under various communication failure scenarios. To test the communication system, it is implemented on an experimental testbed to investigate its functionality for MMG neutral current compensation (NCC). To compensate the neutral current in MMG, a dynamic NCC algorithm is proposed, which enables the MGs to further improve the NCC by sharing their...

Although microgrids facilitate the increased penetration of distributed generations (DGs) and imp... more Although microgrids facilitate the increased penetration of distributed generations (DGs) and improve the security of power supplies, they have some issues that need to be better understood and addressed before realising the full potential of microgrids. This paper presents a comprehensive list of challenges and opportunities supported by a literature review on the evolution of converter-based microgrids. The discussion in this paper presented with a view to establishing microgrids as distinct from the existing distribution systems. This is accomplished by, firstly, describing the challenges and benefits of using DG units in a distribution network and then those of microgrid ones. Also, the definitions, classifications and characteristics of microgrids are revised according to their specific roles to provide a sound basis for novice researchers to undertake ongoing research on microgrids.

Energies, 2017

Distributed generation (DG) is one of the key components of the emerging microgrid concept that e... more Distributed generation (DG) is one of the key components of the emerging microgrid concept that enables renewable energy integration in a distribution network. In DG unit operation, inverters play a vital role in interfacing energy sources with the grid utility. An effective interfacing can successfully be accomplished by operating inverters with effective control techniques. This paper reviews and categorises different control methods (voltage and primary) for improving microgrid power quality, stability and power sharing approaches. In addition, the specific characteristics of microgrids are summarised to distinguish from distribution network control. Moreover, various control approaches including inner-loop controls and primary controls are compared according to their relative advantages and disadvantages. Finally, future research trends for microgrid control are discussed pointing out the research opportunities. This review paper will be a good basis for researchers working in microgrids and for industry to implement the ongoing research improvement in real systems.

2016 Australasian Universities Power Engineering Conference (AUPEC), 2016

Recently transformerless grid-tied photovoltaic (PV) inverters are getting popular in order to ad... more Recently transformerless grid-tied photovoltaic (PV) inverters are getting popular in order to address several concerns; for example, poor efficiency, large size, and heavy weight compared to those with traditional inverter topologies. However, according to the several recently updated grid codes, the grid-tied PV inverter are required to provide full range of services such as maximum power injection, grid voltage regulation (VR), and fault ride through (FRT). In this paper, the performance of a transformerless PV system with a new droop based controller connected to the low voltage distribution system under different operating condition is investigated. In order to provide full-range of grid supporting services, three operation modes are proposed. A detail description of the transformerless PV inverter, droop based controller, and the control strategy are provided. The theoretical analysis is verified using nonlinear simulations in MATLAB/Simulink software environment. The results show that the presented system is capable of injecting maximum power when participate in the grid voltage regulation, and also can enhance fault ride through capability.

IEEE Journal of Photovoltaics, 2014

ABSTRACT This paper presents a robust stabilization scheme for a three-phase grid-connected photo... more ABSTRACT This paper presents a robust stabilization scheme for a three-phase grid-connected photovoltaic system to control the current injected into the grid and dc-link voltage to extract maximum power from photovoltaic (PV) units. The scheme is mainly based on the design of a robust controller using a partial feedback linearizing approach of feedback linearization, where the robustness of the proposed scheme is ensured by considering uncertainties within the PV system model. In this paper, the uncertainties are modeled as structured uncertainties based on the satisfaction of matching conditions. The performance of the proposed stabilization scheme is evaluated on a three-phase grid-connected PV system in terms of delivering maximum power under changes in atmospheric conditions.

2014 Australasian Universities Power Engineering Conference (AUPEC), 2014

Voltage and frequency regulations are main requirements for autonomous operation of an isolated m... more Voltage and frequency regulations are main requirements for autonomous operation of an isolated microgrid with electronically interfaced distributed energy resource (DER) units. This paper presents a robust decentralized control design scheme for a multi-DER microgrid to enhance its voltage and frequency regulations. The proposed control scheme utilizes linear quadratic (LQ) decentralized control scheme to design controllers, which are robust to the uncertainty in the network and system nonlinearities. The effectiveness of the proposed controller is demonstrated through simulation on a test system, with complete nonlinear models, for large disturbances. It is found that the designed controller provides excellent performance during transient periods as well as restores the pre-disturbance steady-state operation within prescribed time frame.

Global Sustainable Development and Renewable Energy Systems

This chapter presents an overview Photovoltaic (PV) power generation and integration of PV system... more This chapter presents an overview Photovoltaic (PV) power generation and integration of PV systems with power grid. This chapter also presents a Feedback Linearizing Current Controller (FBLCC) to synchronize the PV system with the grid. This controller is designed based on the feedback linearization technique. The reference current for the controller is generated from the Maximum Power Point Tracker (MPPT). The stability of a single-phase grid connected PV system is analyzed through the Lyapunov function. To do these things, a suitable mathematical model of grid-connected PV system is also presented in this chapter. The performance of the designed controller is tested on a single-phase grid-connected PV system.

IEEE Systems Journal, 2012

The complexity of power systems has increased in recent years due to the operation of existing tr... more The complexity of power systems has increased in recent years due to the operation of existing transmission lines closer to their limits, using flexible AC transmission system devices (FACTS), and also due to the increased penetration of new types of generators that have more intermittent characteristics and lower inertial response, such as wind generators. This changing nature of a power system has considerable effect on its dynamic behaviours resulting in power swings, dynamic interactions between different power system devices and less synchronized coupling. This paper presents some analyses of this changing nature of power systems and their dynamic behaviours to identify critical issues that limit the large-scale integration of wind generators and FACTS devices. In addition, this paper addresses some general concerns towards high compensations in different grid topologies. The studies in this paper are conducted on the New England and New York power system model under both small and large disturbances. From the analyses, it can be concluded that high compensation can reduce the security limits under certain operating conditions, and the modes related to operating slip and shaft stiffness are critical as they may limit the large-scale integration of wind generation.