Vassilios agelidis - Academia.edu (original) (raw)

Papers by Vassilios agelidis

Research paper thumbnail of A Method Without Stability Issue for Robust Estimation of Three-Phase Grid Frequency

IEEE Journal of Emerging and Selected Topics in Industrial Electronics, 2021

 Users may download and print one copy of any publication from the public portal for the purpose... more  Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Research paper thumbnail of Fast Estimation of Phase Angle for Three-Phase Voltage Systems Under Distorted Conditions

IEEE Journal of Emerging and Selected Topics in Power Electronics, 2020

 Users may download and print one copy of any publication from the public portal for the purpose... more  Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Research paper thumbnail of Comparison of bipolar sub-modules for the alternate arm converter

IECON 2016 - 42nd Annual Conference of the IEEE Industrial Electronics Society, 2016

Research on dc-fault tolerant multilevel converters has gained noticeable attention over recent y... more Research on dc-fault tolerant multilevel converters has gained noticeable attention over recent years. The alternate arm converter (AAC) is one of such emerging multilevel converter topologies, and a hybrid topology of the two-level converter and the modular multilevel converter (MMC). Bipolar submodules (SMs) that can produce both positive and negative voltages are the building blocks of the AAC. This paper analyses the operation of an AAC with the full-bridge SM (FB-SM) and the crossconnected SM (CC-SM). The conduction and switching losses of the two SM configurations are evaluated and compared, in order to identify the suitability of CC-SM for AACs and its performance compared to the FB-SM. The CC-SM with identical semiconductor devices has reduced losses compared to the CC-SM with higher rated devices in the cross-connected path. It is concluded that the CC-SM does not offer advantages in the losses, construction, and application to the AAC, compared to FB-SM. Index Terms-Alternate arm converter, cross-connected submodules, losses, identical semiconductor devices.

Research paper thumbnail of Predictive Control of Cascaded H-Bridge Converters Under Unbalanced Power Generation

IEEE Transactions on Industrial Electronics, 2017

This work presents a predictive control strategy for grid-connected Cascaded H-Bridge (CHB) conve... more This work presents a predictive control strategy for grid-connected Cascaded H-Bridge (CHB) converters under unbalanced power generation among each converter phase. The proposed controller belongs to the Finite-Control-Set Model Predictive Control (FCS-MPC) family and is designed to extract unbalanced power from each CHB converter phase while providing balanced power to the grid. The key novelty of this strategy lies in the way the unbalanced power generation among the phases is explicitly considered into the optimal control problem. Power balance is achieved by enforcing the CHB converter to work with a suitable zero-sequence voltage component. The proposed predictive controller is directly formulated in the original abc-framework to account for the commonmode voltage. Simulation and experimental results are provided to verify the effectiveness of the proposed FCS-MPC strategy.

Research paper thumbnail of A Review of Power Electronics for Grid Connection of Utility-Scale Battery Energy Storage Systems

IEEE Transactions on Sustainable Energy, 2016

The increasing penetration of renewable energy sources (RES) poses a major challenge to the opera... more The increasing penetration of renewable energy sources (RES) poses a major challenge to the operation of the electricity grid owing to the intermittent nature of their power output. The ability of utility-scale battery energy storage systems (BESS) to provide grid support and smooth the output of RES in combination with their decrease in cost has fueled research interest in this technology over the last couple of years. Power electronics (PE) is the key enabling technology for connecting utility-scale BESS to the medium voltage grid. PE ensure energy is delivered while complying with grid codes and dispatch orders. Simultaneously, the PE must regulate the operating point of the batteries, thus for instance preventing overcharge of batteries. This paper presents a comprehensive review of PE topologies for utility BESS that have been proposed either within industry or the academic literature. Moreover, a comparison of the presently most commercially viable topologies is conducted in terms of estimated power conversion efficiency and relative cost.

Research paper thumbnail of Reliability Optimization of Automated Distribution Networks With Probability Customer Interruption Cost Model in the Presence of DG Units

IEEE Transactions on Smart Grid, 2017

Distribution automation systems in terms of automatic and remote-controlled sectionalizing switch... more Distribution automation systems in terms of automatic and remote-controlled sectionalizing switches allows distribution utilities to implement flexible control of distribution networks, which is a successful strategy to enhance efficiency, reliability and quality of service. The sectionalizing switches play a significant role in an automated distribution network, hence optimizing the allocation of switches can improve the quality of supply and reliability indices. This paper presents a mixedinteger nonlinear programming aiming to model the optimal placement of manual and automatic sectionalizing switches and protective devices in distribution networks. A value-based reliability optimization formulation is derived from the proposed model to take into consideration customer interruption cost and related costs of sectionalizing switches and protective devices. A probability distribution cost model is developed based on a cascade correlation neural network to have a more accurate reliability assessment. To ensure the effectiveness of the proposed formulation both technical and economic constraints are considered. Furthermore, introducing distributed generation into distribution networks is also considered subject to the island operation of DG units. The performance of the proposed approach is assessed and illustrated by studying on the bus 4 of the RBTS standard test system. The simulation results verify the capability and accuracy of the proposed approach.

Research paper thumbnail of Cooperative Multi-Agent Control of Heterogeneous Storage Devices Distributed in a DC Microgrid

IEEE Transactions on Power Systems, 2016

This paper proposes a multi-agent control strategy to coordinate power sharing between heterogene... more This paper proposes a multi-agent control strategy to coordinate power sharing between heterogeneous energy storage devices distributed throughout a DC microgrid. Without requiring a central controller, the proposed control strategy extends the benefits offered by hybrid energy storage systems to DC microgrids with batteries and ultracapacitors spatially distributed at different levels of the power distribution hierarchy. The proposed control strategy has the following advantages. 1) The high frequency microgrid load is provided by the ultracapacitors. 2) The low frequency load is provided by batteries used for bulk energy storage during islanded mode, and the main grid during grid connected operation. 3) The ultracapacitor voltages are regulated at a desired reference. 4) State of charge balancing is provided between the batteries. 5) The energy storage systems cooperate based on neighbor-to-neighbor output feedback over a sparse communication network. The only communication requirement is a spanning tree from the ultracapacitor leaders and battery leaders to their respective followers. Simulations are presented demonstrating the performance of the proposed control strategy for a 380 VDC datacenter during grid connected and islanded operation.

Research paper thumbnail of Cascade-Free Model Predictive Control for Single-Phase Grid-Connected Power Converters

IEEE Transactions on Industrial Electronics, 2017

In a conventional FCS-MPC formulation, active and reactive power control loops rely on the predic... more In a conventional FCS-MPC formulation, active and reactive power control loops rely on the predictive controller while the dc-bus voltage is usually governed by a PI-based control loop. This comes from fact that the dynamic equations for describing the predictions of these variables are heavily coupled. In this paper, a cascadefree finite control set model predictive control (FCS-MPC) for single-phase grid-connected power converters is presented. The proposed control algorithm is formulated in terms of established dynamic references design, which was originally proposed to directly govern active and reactive power, and dc-voltage in three-phase power converters. In this work, the dynamic reference design concept is extended to control single-phase grid-connected power converters. The proposed control algorithm does not use instantaneous ac-power calculations; instead it directly formulates the optimal control problem on the grid-current in the original stationary reference frame. The experimental results obtained with a single-phase grid-connected Neutral Point Clamped (NPC) converter confirm a successful design, where system constraints, e.g. maximum power and weighted switching frequency, are easily taken into account.

Research paper thumbnail of Decentralised control method for DC microgrids with improved current sharing accuracy

IET Generation, Transmission & Distribution, 2017

 Users may download and print one copy of any publication from the public portal for the purpose... more  Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Research paper thumbnail of Predictive Control algorithm to achieve power balance of Cascaded H-Bridge converters

2015 IEEE International Symposium on Predictive Control of Electrical Drives and Power Electronics (PRECEDE), 2015

This work proposes a Model Predictive Control (MPC) strategy for Cascaded H-Bridge (CHB) converte... more This work proposes a Model Predictive Control (MPC) strategy for Cascaded H-Bridge (CHB) converters under unbalanced power generation among each converter phase. Therefore, the control target is to extract unbalanced power from the dc-sources while providing balanced power to the grid. The key novelty of this proposal lies in the way the unbalanced power generation issue is explicitly considered into the optimal control problem. The power balance is achieved by enforcing the CHB to work with a suitable zero voltage components. Thus, to account for the common-mode voltage, the proposed MPC is directly formulated in the original abc-framework. To verify the effectiveness of this proposal, simulation results of the proposed MPC governing a five-level CHB converter are provided.

Research paper thumbnail of Delta-connected cascaded H-bridge multilevel photovoltaic converters

IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society, 2015

Multilevel cascaded H-bridge converters are becoming popular for next generation large-scale phot... more Multilevel cascaded H-bridge converters are becoming popular for next generation large-scale photovoltaic power converters. However, the power generation levels in the three phases can be significantly unequal, especially in a large plant, owing to the non-uniform irradiance levels and/or ambient temperatures. This paper proposes the delta-connected cascaded H-bridge converter for large-scale photovoltaic farms. Compared to the existing star connection, the delta connection reduces the converter overrating required. Experimental results obtained from a 430 V, 10 kW, three-phase, seven-level, delta connected cascaded H-bridge converter prototype are provided to demonstrate the superiority of the delta connection.

Research paper thumbnail of Optimal Robust Unit Commitment of CHP Plants in Electricity Markets Using Information Gap Decision Theory

IEEE Transactions on Smart Grid, 2017

This paper proposes a novel method based on information gap decision theory to evaluate a profita... more This paper proposes a novel method based on information gap decision theory to evaluate a profitable operation strategy for combined heat and power units in a liberalized electricity market. Risk levels can be assessed using this technique, taking into consideration whether the generation company is either risk-taking or risk averse. The test system used in this paper comprises conventional thermal, cogeneration, and heat-only units. The pool price is considered to be uncertain while an information gap decision theory method is employed to model its volatility around the estimated value. Profits lower than the expected value are optimized using the proposed method and the related strategy is determined. The presented method optimizes the opportunities to make use of high profits or high pool prices. To verify the performance of the proposed method, the model has been implemented on a case study. Keywords Combined heat and power unit, risk, information gap decision theory, robust strategy.

Research paper thumbnail of Uncertainty management in multiobjective hydro-thermal self-scheduling under emission considerations

Applied Soft Computing, 2015

In this paper, a stochastic multiobjective framework is proposed for a day-ahead short-term Hydro... more In this paper, a stochastic multiobjective framework is proposed for a day-ahead short-term Hydro Thermal Self-Scheduling (HTSS) problem for joint energy and reserve markets. An efficient linear formulations are introduced in this paper to deal with the nonlinearity of original problem due to the dynamic ramp rate limits, prohibited operating zones, operating services of thermal plants, multi-head power discharge characteristics of hydro generating units and spillage of reservoirs. Besides, system uncertainties including the generating units' contingencies and price uncertainty are explicitly considered in the stochastic market clearing scheme. For the stochastic modeling of probable multiobjective optimization scenarios, a lattice Monte Carlo simulation has been adopted to have a better coverage of the system uncertainty spectrum. Consequently, the resulting multiobjective optimization scenarios should concurrently optimize competing objective functions including GENeration COmpany's (GENCO's) profit maximization and thermal units' emission minimization. Accordingly, the ε-constraint method is used to solve the multiobjective optimization problem and generate the Pareto set. Then, a fuzzy satisfying method is employed to choose the most preferred solution among all Pareto optimal solutions. The performance of the presented method is verified in different case studies. The results obtained from ε-constraint method is compared with those reported by weighted sum method, evolutionary programming-based interactive Fuzzy satisfying method, differential evolution, quantumbehaved particle swarm optimization and hybrid multi-objective cultural algorithm, verifying the superiority of the proposed approach.

Research paper thumbnail of Interleaved Operation of Three-Level Neutral Point Clamped Converter Legs and Reduction of Circulating Currents Under SHE-PWM

IEEE Transactions on Industrial Electronics, 2016

Interleaving of voltage source converter legs enables higher output currents per phase, effective... more Interleaving of voltage source converter legs enables higher output currents per phase, effectively increasing the power rating without increasing semiconductor ratings. However, the interleaved operation results in circulating currents between each phase converter legs as well as a zero-sequence circulating current which become quite prominent when the converters operate with low switching frequencies. This paper demonstrates the interleaved operation of three-level converters under selective harmonic elimination pulse-width modulation (SHE-PWM). A controller for the circulating current within the legs of each phase is also proposed. The controller is used in combination with optimally selected SHE-PWM patterns to generate the maximum number of voltage levels and minimise the peak value of the circulating current. Simulation and experimental results show the interleaved operation and the effect of SHE-PWM pattern selection in the overall system.

Research paper thumbnail of Front-End Power Converter Topologies for Plug-In Electric Vehicles

Emerging Power Converters for Renewable Energy and Electric Vehicles, 2021

Research paper thumbnail of Neural Network Approach for Global Solar Irradiance Prediction at Extremely Short-Time-Intervals Using Particle Swarm Optimization Algorithm

Energies, 2021

Hourly global solar irradiance (GSR) data are required for sizing, planning, and modeling of sola... more Hourly global solar irradiance (GSR) data are required for sizing, planning, and modeling of solar photovoltaic farms. However, operating and controlling such farms exposed to varying environmental conditions, such as fast passing clouds, necessitates GSR data to be available for very short time intervals. Classical backpropagation neural networks do not perform satisfactorily when predicting parameters within short intervals. This paper proposes a hybrid backpropagation neural networks based on particle swarm optimization. The particle swarm algorithm is used as an optimization algorithm within the backpropagation neural networks to optimize the number of hidden layers and neurons used and its learning rate. The proposed model can be used as a reliable model in predicting changes in the solar irradiance during short time interval in tropical regions such as Malaysia and other regions. Actual global solar irradiance data of 5-s and 1-min intervals, recorded by weather stations, are ...

Research paper thumbnail of Application of an adaptive Bayesian‐based model for probabilistic and deterministic PV forecasting

IET Renewable Power Generation, 2021

Accurate prediction of solar photovoltaic plant energy generation is essential for optimal planni... more Accurate prediction of solar photovoltaic plant energy generation is essential for optimal planning and operation of modern power systems, and incorporating such plants into the energy sector. In this study, an adaptive Gaussian mixture method (AGM) and a developed variational Bayesian model (VBM) inference through multikernel regression (MkR) are utilized to assist desirable precise prediction. In this model, the MkR processes the multiresolution solar energy signal, and then the AGM models the complex signals forecasting error. Finally, the proposed model can be optimized, and the concurrent output of the solar energy signal in both probabilistic and deterministic status can be attained through the introduction of the VBM. The solar energy output of an actual plant, including four measurement sites provided the data for the study. The results confirmed that the proposed model delivers higher prediction accuracy for both probabilistic and deterministic forecasts when compared with other well-known models. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Research paper thumbnail of Wind-Energy-Powered Electric Vehicle Charging Stations: Resource Availability Data Analysis

Applied Sciences, 2020

The integration of large-scale wind farms and large-scale charging stations for electric vehicles... more The integration of large-scale wind farms and large-scale charging stations for electric vehicles (EVs) into electricity grids necessitates energy storage support for both technologies. Matching the variability of the energy generation of wind farms with the demand variability of the EVs could potentially minimize the size and need for expensive energy storage technologies required to stabilize the grid. This paper investigates the feasibility of using the wind as a direct energy source to power EV charging stations. An interval-based approach corresponding to the time slot taken for EV charging is introduced for wind energy conversion and analyzed using different constraints and criteria, including the wind speed averaging time interval, various turbines manufacturers, and standard high-resolution wind speed datasets. A quasi-continuous wind turbine’s output energy is performed using a piecewise recursive approach to measure the EV charging effectiveness. Wind turbine analysis usin...

Research paper thumbnail of Closed-loop SHE-PWM technique for power converters through Model Predictive Control

IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society, 2015

In this work, a Model Predictive Control (MPC) strategy that combines Finite-Control-Set MPC (FCS... more In this work, a Model Predictive Control (MPC) strategy that combines Finite-Control-Set MPC (FCS-MPC) with Selective Harmonic Elimination (SHE) modulation pattern in its formulation is proposed to govern power converters. The key idea here is to define a desired steady-state in terms of the converter current and voltage. To do this, based on the converter current (system state) reference, an associated predefined SHE pattern is used as control input reference. Both system state and control references are included in the cost function. Therefore, during transients, the resulting predictive controller prefers to track the converter current while preserving the SHE pattern during steady-state. Thus, a fast dynamic response can be achieved throughout transients while a predefined voltage and current spectrum with low commutation frequency is obtained in steady-state by adjusting only the weighting factor of the cost function. Simulation results of the proposed SHE-MPC strategy when governing a Cascaded H-Bridge (CHB) converter are presented to highlight the benefits of the proposed predictive controller.

Research paper thumbnail of The future of power electronics/power engineering education: challenges and opportunities

IEEE Workshop Power Electronics Education, 2005., 2005

This paper discusses some factors affecting the education sector in the power electronics/power e... more This paper discusses some factors affecting the education sector in the power electronics/power engineering area along with the renewed challenges and opportunities in the light of so many recent R&D developments at system level. It provides an overview of university-based curriculum initiatives and modern methods of instruction encouraging life long learning culture based on problem and project-based learning. The design studio approach currently used at Murdoch University, Perth, Western Australia is outlined. This approach is mapped to the modern attributes of engineering graduates along with Bloom's taxonomic levels of the cognitive domain. It is recognized that the aim should be to achieve learning in the highest possible level of the cognitive domain and the project-based approach is identified as the way forward. Finally, the assessment of students by an industrial panel is also presented as a complementary way to interact with the industry and involve their feedback directly with the educational process. I.

Research paper thumbnail of A Method Without Stability Issue for Robust Estimation of Three-Phase Grid Frequency

IEEE Journal of Emerging and Selected Topics in Industrial Electronics, 2021

 Users may download and print one copy of any publication from the public portal for the purpose... more  Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Research paper thumbnail of Fast Estimation of Phase Angle for Three-Phase Voltage Systems Under Distorted Conditions

IEEE Journal of Emerging and Selected Topics in Power Electronics, 2020

 Users may download and print one copy of any publication from the public portal for the purpose... more  Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Research paper thumbnail of Comparison of bipolar sub-modules for the alternate arm converter

IECON 2016 - 42nd Annual Conference of the IEEE Industrial Electronics Society, 2016

Research on dc-fault tolerant multilevel converters has gained noticeable attention over recent y... more Research on dc-fault tolerant multilevel converters has gained noticeable attention over recent years. The alternate arm converter (AAC) is one of such emerging multilevel converter topologies, and a hybrid topology of the two-level converter and the modular multilevel converter (MMC). Bipolar submodules (SMs) that can produce both positive and negative voltages are the building blocks of the AAC. This paper analyses the operation of an AAC with the full-bridge SM (FB-SM) and the crossconnected SM (CC-SM). The conduction and switching losses of the two SM configurations are evaluated and compared, in order to identify the suitability of CC-SM for AACs and its performance compared to the FB-SM. The CC-SM with identical semiconductor devices has reduced losses compared to the CC-SM with higher rated devices in the cross-connected path. It is concluded that the CC-SM does not offer advantages in the losses, construction, and application to the AAC, compared to FB-SM. Index Terms-Alternate arm converter, cross-connected submodules, losses, identical semiconductor devices.

Research paper thumbnail of Predictive Control of Cascaded H-Bridge Converters Under Unbalanced Power Generation

IEEE Transactions on Industrial Electronics, 2017

This work presents a predictive control strategy for grid-connected Cascaded H-Bridge (CHB) conve... more This work presents a predictive control strategy for grid-connected Cascaded H-Bridge (CHB) converters under unbalanced power generation among each converter phase. The proposed controller belongs to the Finite-Control-Set Model Predictive Control (FCS-MPC) family and is designed to extract unbalanced power from each CHB converter phase while providing balanced power to the grid. The key novelty of this strategy lies in the way the unbalanced power generation among the phases is explicitly considered into the optimal control problem. Power balance is achieved by enforcing the CHB converter to work with a suitable zero-sequence voltage component. The proposed predictive controller is directly formulated in the original abc-framework to account for the commonmode voltage. Simulation and experimental results are provided to verify the effectiveness of the proposed FCS-MPC strategy.

Research paper thumbnail of A Review of Power Electronics for Grid Connection of Utility-Scale Battery Energy Storage Systems

IEEE Transactions on Sustainable Energy, 2016

The increasing penetration of renewable energy sources (RES) poses a major challenge to the opera... more The increasing penetration of renewable energy sources (RES) poses a major challenge to the operation of the electricity grid owing to the intermittent nature of their power output. The ability of utility-scale battery energy storage systems (BESS) to provide grid support and smooth the output of RES in combination with their decrease in cost has fueled research interest in this technology over the last couple of years. Power electronics (PE) is the key enabling technology for connecting utility-scale BESS to the medium voltage grid. PE ensure energy is delivered while complying with grid codes and dispatch orders. Simultaneously, the PE must regulate the operating point of the batteries, thus for instance preventing overcharge of batteries. This paper presents a comprehensive review of PE topologies for utility BESS that have been proposed either within industry or the academic literature. Moreover, a comparison of the presently most commercially viable topologies is conducted in terms of estimated power conversion efficiency and relative cost.

Research paper thumbnail of Reliability Optimization of Automated Distribution Networks With Probability Customer Interruption Cost Model in the Presence of DG Units

IEEE Transactions on Smart Grid, 2017

Distribution automation systems in terms of automatic and remote-controlled sectionalizing switch... more Distribution automation systems in terms of automatic and remote-controlled sectionalizing switches allows distribution utilities to implement flexible control of distribution networks, which is a successful strategy to enhance efficiency, reliability and quality of service. The sectionalizing switches play a significant role in an automated distribution network, hence optimizing the allocation of switches can improve the quality of supply and reliability indices. This paper presents a mixedinteger nonlinear programming aiming to model the optimal placement of manual and automatic sectionalizing switches and protective devices in distribution networks. A value-based reliability optimization formulation is derived from the proposed model to take into consideration customer interruption cost and related costs of sectionalizing switches and protective devices. A probability distribution cost model is developed based on a cascade correlation neural network to have a more accurate reliability assessment. To ensure the effectiveness of the proposed formulation both technical and economic constraints are considered. Furthermore, introducing distributed generation into distribution networks is also considered subject to the island operation of DG units. The performance of the proposed approach is assessed and illustrated by studying on the bus 4 of the RBTS standard test system. The simulation results verify the capability and accuracy of the proposed approach.

Research paper thumbnail of Cooperative Multi-Agent Control of Heterogeneous Storage Devices Distributed in a DC Microgrid

IEEE Transactions on Power Systems, 2016

This paper proposes a multi-agent control strategy to coordinate power sharing between heterogene... more This paper proposes a multi-agent control strategy to coordinate power sharing between heterogeneous energy storage devices distributed throughout a DC microgrid. Without requiring a central controller, the proposed control strategy extends the benefits offered by hybrid energy storage systems to DC microgrids with batteries and ultracapacitors spatially distributed at different levels of the power distribution hierarchy. The proposed control strategy has the following advantages. 1) The high frequency microgrid load is provided by the ultracapacitors. 2) The low frequency load is provided by batteries used for bulk energy storage during islanded mode, and the main grid during grid connected operation. 3) The ultracapacitor voltages are regulated at a desired reference. 4) State of charge balancing is provided between the batteries. 5) The energy storage systems cooperate based on neighbor-to-neighbor output feedback over a sparse communication network. The only communication requirement is a spanning tree from the ultracapacitor leaders and battery leaders to their respective followers. Simulations are presented demonstrating the performance of the proposed control strategy for a 380 VDC datacenter during grid connected and islanded operation.

Research paper thumbnail of Cascade-Free Model Predictive Control for Single-Phase Grid-Connected Power Converters

IEEE Transactions on Industrial Electronics, 2017

In a conventional FCS-MPC formulation, active and reactive power control loops rely on the predic... more In a conventional FCS-MPC formulation, active and reactive power control loops rely on the predictive controller while the dc-bus voltage is usually governed by a PI-based control loop. This comes from fact that the dynamic equations for describing the predictions of these variables are heavily coupled. In this paper, a cascadefree finite control set model predictive control (FCS-MPC) for single-phase grid-connected power converters is presented. The proposed control algorithm is formulated in terms of established dynamic references design, which was originally proposed to directly govern active and reactive power, and dc-voltage in three-phase power converters. In this work, the dynamic reference design concept is extended to control single-phase grid-connected power converters. The proposed control algorithm does not use instantaneous ac-power calculations; instead it directly formulates the optimal control problem on the grid-current in the original stationary reference frame. The experimental results obtained with a single-phase grid-connected Neutral Point Clamped (NPC) converter confirm a successful design, where system constraints, e.g. maximum power and weighted switching frequency, are easily taken into account.

Research paper thumbnail of Decentralised control method for DC microgrids with improved current sharing accuracy

IET Generation, Transmission & Distribution, 2017

 Users may download and print one copy of any publication from the public portal for the purpose... more  Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Research paper thumbnail of Predictive Control algorithm to achieve power balance of Cascaded H-Bridge converters

2015 IEEE International Symposium on Predictive Control of Electrical Drives and Power Electronics (PRECEDE), 2015

This work proposes a Model Predictive Control (MPC) strategy for Cascaded H-Bridge (CHB) converte... more This work proposes a Model Predictive Control (MPC) strategy for Cascaded H-Bridge (CHB) converters under unbalanced power generation among each converter phase. Therefore, the control target is to extract unbalanced power from the dc-sources while providing balanced power to the grid. The key novelty of this proposal lies in the way the unbalanced power generation issue is explicitly considered into the optimal control problem. The power balance is achieved by enforcing the CHB to work with a suitable zero voltage components. Thus, to account for the common-mode voltage, the proposed MPC is directly formulated in the original abc-framework. To verify the effectiveness of this proposal, simulation results of the proposed MPC governing a five-level CHB converter are provided.

Research paper thumbnail of Delta-connected cascaded H-bridge multilevel photovoltaic converters

IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society, 2015

Multilevel cascaded H-bridge converters are becoming popular for next generation large-scale phot... more Multilevel cascaded H-bridge converters are becoming popular for next generation large-scale photovoltaic power converters. However, the power generation levels in the three phases can be significantly unequal, especially in a large plant, owing to the non-uniform irradiance levels and/or ambient temperatures. This paper proposes the delta-connected cascaded H-bridge converter for large-scale photovoltaic farms. Compared to the existing star connection, the delta connection reduces the converter overrating required. Experimental results obtained from a 430 V, 10 kW, three-phase, seven-level, delta connected cascaded H-bridge converter prototype are provided to demonstrate the superiority of the delta connection.

Research paper thumbnail of Optimal Robust Unit Commitment of CHP Plants in Electricity Markets Using Information Gap Decision Theory

IEEE Transactions on Smart Grid, 2017

This paper proposes a novel method based on information gap decision theory to evaluate a profita... more This paper proposes a novel method based on information gap decision theory to evaluate a profitable operation strategy for combined heat and power units in a liberalized electricity market. Risk levels can be assessed using this technique, taking into consideration whether the generation company is either risk-taking or risk averse. The test system used in this paper comprises conventional thermal, cogeneration, and heat-only units. The pool price is considered to be uncertain while an information gap decision theory method is employed to model its volatility around the estimated value. Profits lower than the expected value are optimized using the proposed method and the related strategy is determined. The presented method optimizes the opportunities to make use of high profits or high pool prices. To verify the performance of the proposed method, the model has been implemented on a case study. Keywords Combined heat and power unit, risk, information gap decision theory, robust strategy.

Research paper thumbnail of Uncertainty management in multiobjective hydro-thermal self-scheduling under emission considerations

Applied Soft Computing, 2015

In this paper, a stochastic multiobjective framework is proposed for a day-ahead short-term Hydro... more In this paper, a stochastic multiobjective framework is proposed for a day-ahead short-term Hydro Thermal Self-Scheduling (HTSS) problem for joint energy and reserve markets. An efficient linear formulations are introduced in this paper to deal with the nonlinearity of original problem due to the dynamic ramp rate limits, prohibited operating zones, operating services of thermal plants, multi-head power discharge characteristics of hydro generating units and spillage of reservoirs. Besides, system uncertainties including the generating units' contingencies and price uncertainty are explicitly considered in the stochastic market clearing scheme. For the stochastic modeling of probable multiobjective optimization scenarios, a lattice Monte Carlo simulation has been adopted to have a better coverage of the system uncertainty spectrum. Consequently, the resulting multiobjective optimization scenarios should concurrently optimize competing objective functions including GENeration COmpany's (GENCO's) profit maximization and thermal units' emission minimization. Accordingly, the ε-constraint method is used to solve the multiobjective optimization problem and generate the Pareto set. Then, a fuzzy satisfying method is employed to choose the most preferred solution among all Pareto optimal solutions. The performance of the presented method is verified in different case studies. The results obtained from ε-constraint method is compared with those reported by weighted sum method, evolutionary programming-based interactive Fuzzy satisfying method, differential evolution, quantumbehaved particle swarm optimization and hybrid multi-objective cultural algorithm, verifying the superiority of the proposed approach.

Research paper thumbnail of Interleaved Operation of Three-Level Neutral Point Clamped Converter Legs and Reduction of Circulating Currents Under SHE-PWM

IEEE Transactions on Industrial Electronics, 2016

Interleaving of voltage source converter legs enables higher output currents per phase, effective... more Interleaving of voltage source converter legs enables higher output currents per phase, effectively increasing the power rating without increasing semiconductor ratings. However, the interleaved operation results in circulating currents between each phase converter legs as well as a zero-sequence circulating current which become quite prominent when the converters operate with low switching frequencies. This paper demonstrates the interleaved operation of three-level converters under selective harmonic elimination pulse-width modulation (SHE-PWM). A controller for the circulating current within the legs of each phase is also proposed. The controller is used in combination with optimally selected SHE-PWM patterns to generate the maximum number of voltage levels and minimise the peak value of the circulating current. Simulation and experimental results show the interleaved operation and the effect of SHE-PWM pattern selection in the overall system.

Research paper thumbnail of Front-End Power Converter Topologies for Plug-In Electric Vehicles

Emerging Power Converters for Renewable Energy and Electric Vehicles, 2021

Research paper thumbnail of Neural Network Approach for Global Solar Irradiance Prediction at Extremely Short-Time-Intervals Using Particle Swarm Optimization Algorithm

Energies, 2021

Hourly global solar irradiance (GSR) data are required for sizing, planning, and modeling of sola... more Hourly global solar irradiance (GSR) data are required for sizing, planning, and modeling of solar photovoltaic farms. However, operating and controlling such farms exposed to varying environmental conditions, such as fast passing clouds, necessitates GSR data to be available for very short time intervals. Classical backpropagation neural networks do not perform satisfactorily when predicting parameters within short intervals. This paper proposes a hybrid backpropagation neural networks based on particle swarm optimization. The particle swarm algorithm is used as an optimization algorithm within the backpropagation neural networks to optimize the number of hidden layers and neurons used and its learning rate. The proposed model can be used as a reliable model in predicting changes in the solar irradiance during short time interval in tropical regions such as Malaysia and other regions. Actual global solar irradiance data of 5-s and 1-min intervals, recorded by weather stations, are ...

Research paper thumbnail of Application of an adaptive Bayesian‐based model for probabilistic and deterministic PV forecasting

IET Renewable Power Generation, 2021

Accurate prediction of solar photovoltaic plant energy generation is essential for optimal planni... more Accurate prediction of solar photovoltaic plant energy generation is essential for optimal planning and operation of modern power systems, and incorporating such plants into the energy sector. In this study, an adaptive Gaussian mixture method (AGM) and a developed variational Bayesian model (VBM) inference through multikernel regression (MkR) are utilized to assist desirable precise prediction. In this model, the MkR processes the multiresolution solar energy signal, and then the AGM models the complex signals forecasting error. Finally, the proposed model can be optimized, and the concurrent output of the solar energy signal in both probabilistic and deterministic status can be attained through the introduction of the VBM. The solar energy output of an actual plant, including four measurement sites provided the data for the study. The results confirmed that the proposed model delivers higher prediction accuracy for both probabilistic and deterministic forecasts when compared with other well-known models. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Research paper thumbnail of Wind-Energy-Powered Electric Vehicle Charging Stations: Resource Availability Data Analysis

Applied Sciences, 2020

The integration of large-scale wind farms and large-scale charging stations for electric vehicles... more The integration of large-scale wind farms and large-scale charging stations for electric vehicles (EVs) into electricity grids necessitates energy storage support for both technologies. Matching the variability of the energy generation of wind farms with the demand variability of the EVs could potentially minimize the size and need for expensive energy storage technologies required to stabilize the grid. This paper investigates the feasibility of using the wind as a direct energy source to power EV charging stations. An interval-based approach corresponding to the time slot taken for EV charging is introduced for wind energy conversion and analyzed using different constraints and criteria, including the wind speed averaging time interval, various turbines manufacturers, and standard high-resolution wind speed datasets. A quasi-continuous wind turbine’s output energy is performed using a piecewise recursive approach to measure the EV charging effectiveness. Wind turbine analysis usin...

Research paper thumbnail of Closed-loop SHE-PWM technique for power converters through Model Predictive Control

IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society, 2015

In this work, a Model Predictive Control (MPC) strategy that combines Finite-Control-Set MPC (FCS... more In this work, a Model Predictive Control (MPC) strategy that combines Finite-Control-Set MPC (FCS-MPC) with Selective Harmonic Elimination (SHE) modulation pattern in its formulation is proposed to govern power converters. The key idea here is to define a desired steady-state in terms of the converter current and voltage. To do this, based on the converter current (system state) reference, an associated predefined SHE pattern is used as control input reference. Both system state and control references are included in the cost function. Therefore, during transients, the resulting predictive controller prefers to track the converter current while preserving the SHE pattern during steady-state. Thus, a fast dynamic response can be achieved throughout transients while a predefined voltage and current spectrum with low commutation frequency is obtained in steady-state by adjusting only the weighting factor of the cost function. Simulation results of the proposed SHE-MPC strategy when governing a Cascaded H-Bridge (CHB) converter are presented to highlight the benefits of the proposed predictive controller.

Research paper thumbnail of The future of power electronics/power engineering education: challenges and opportunities

IEEE Workshop Power Electronics Education, 2005., 2005

This paper discusses some factors affecting the education sector in the power electronics/power e... more This paper discusses some factors affecting the education sector in the power electronics/power engineering area along with the renewed challenges and opportunities in the light of so many recent R&D developments at system level. It provides an overview of university-based curriculum initiatives and modern methods of instruction encouraging life long learning culture based on problem and project-based learning. The design studio approach currently used at Murdoch University, Perth, Western Australia is outlined. This approach is mapped to the modern attributes of engineering graduates along with Bloom's taxonomic levels of the cognitive domain. It is recognized that the aim should be to achieve learning in the highest possible level of the cognitive domain and the project-based approach is identified as the way forward. Finally, the assessment of students by an industrial panel is also presented as a complementary way to interact with the industry and involve their feedback directly with the educational process. I.