Razzaqul Ahshan - Academia.edu (original) (raw)

Papers by Razzaqul Ahshan

IEEE Access

Appropriate renewable distributed generation (RDG) placement is one of the most significant issue... more Appropriate renewable distributed generation (RDG) placement is one of the most significant issues for the efficient operation of current power systems. Since the inverter-interfaced RDG lacks rotating mass to sustain the system's inertia, microgrids have low total system inertia, which impairs frequency stability and can yield significant frequency and voltage instability in severe disruptions. The virtual synchronous generator (VSG), which uses concepts that regulate the inverter to simulate a conventional synchronous generator, is one of the most promising solutions to address these challenges. Hence, this research proposes a unique technique of simultaneous optimal solution for RDG and VSG sizing and placement in distribution networks using a recent metaheuristic technique called the Multi-objective Salp Swarm Optimization Algorithm (MOSSA). The objective function was to minimize the frequency deviation and maximize the total annual energy savings and operational costs of the RDG and VSG units. This study assesses IEEE 33 bus, 69 bus distribution network, and practical Masirah network as the test systems. Moreover, the MOSSA Pareto fronts are superior to two recent metaheuristics employed in this research domain: Multi-objective Particle Swarm Optimization (MOPSO) and Non-dominated Sorting Genetic Algorithm-II (NSGA-II). The results demonstrate that the MOSSA Pareto fronts satisfied the frequency and energy-saving objectives. In addition, all Pareto fronts accurately prevented voltage limit infringements, and the overall energy losses were significantly reduced. INDEX TERMS Virtual synchronous generator, optimization, multi-objective algorithm, renewable energy, distributed generation. NOMENCLATURE b Branch index. i Bus index. NBR Total number of branches P gen Actual power generation. P load Active demand. P loss Active loss. Q gen Reactive generation. Qr load Reactive demand. The associate editor coordinating the review of this manuscript and approving it for publication was Rajesh Kumar. Qr loss Reactive loss. S l Power transmitted in branch l. Vm bus Voltage at a certain bus. C RDG/VSG Cost per kW of injected power. S RDG/VSG,m Size of m th RDG/VSG. S RDG/VSG,max Allowable maximum size. T RDG/VSG Total RDG/VSG lifetime in years. C E Average cost of energy loss per kWh. R Rate of interest on capital investment of the installed RDG-VSG. AEL T ,RDG/VSG Total annual economic loss with RDG/VSG.

2021 IEEE Industry Applications Society Annual Meeting (IAS), Oct 10, 2021

This paper presents a method for evaluating smart grid functions that are implemented to operate ... more This paper presents a method for evaluating smart grid functions that are implemented to operate residential loads. The proposed assessment method is developed based on the energy not-served (ENS) determined at a point-of-supply feeding residential loads. Smart grid functions can operate energy storage appliances (household water heaters, air conditioners, and heating units) to store thermal energy during the daily off-peak-demand hours. The stored thermal energy is discharged during the daily peak-demand hours, thus reducing the power demands of residential loads. The differences in daily energy demands created by smart grid functions can provide an accurate assessment of the effectiveness of smart grid functions. The ENS-based method is tested for 200 residential households fed from 4 distribution transformers, and are operated by smart grid functions. In these tests, smart grid functions are implemented by the peak-demand management, direct load control, and demand response. Test results demonstrate the accuracy and simplicity of the ENS-based method to assess smart grid functions in terms of the ability to reduce the power demands of residential loads during peak-demand hours.

2022 IEEE Industry Applications Society Annual Meeting (IAS), Oct 9, 2022

Energies

Power system stability is greatly affected by two types of stochastic or random disturbances: (1)... more Power system stability is greatly affected by two types of stochastic or random disturbances: (1) topological and (2) parametric. The topological stochastic disturbances due to line faults caused by a series of lightning strikes (associated with circuit breaker, C.B., opening, and auto-reclosing) are modeled in this paper as continuous-time Markov jumps. Additionally, the stochastic parameter changes e.g., the line reactance, are influenced by the phase separation, which in turn depends on the stochastic wind speed. This is modeled as a stochastic disturbance. In this manuscript, the impact of the above stochastic disturbance on power system small-disturbance stability is studied based on stochastic differential equations (SDEs). The mean-square stabilization of such a system is conducted through a novel excitation control. The invariant ellipsoid and linear matrix inequality (LMI) optimization are used to construct the control system. The numerical simulations are presented on a mu...

International Journal of Renewable Energy Research

This paper presents the design and economic analysis of a photovoltaic (PV) system for a campus s... more This paper presents the design and economic analysis of a photovoltaic (PV) system for a campus sports complex located at the Sultan Qaboos University (SQU) in Oman. The designed PV system shows the ability to serve the total energy required by the various playgrounds in the sports complex and to sell excess power to the grid. Oman is one of the gulf countries that has the highest average solar irradiation. Besides, the temperature in Oman varies in a broad spectrum daily and seasonally. This variation in temperature, especially in a hot climate like in Oman, has a significant impact on the PV output. This paper addresses such a change of temperature in designing the PV system for the sports complex. This paper also presents the mathematical model utilized in designing the PV system and its design process in detail. The outcome of the design shows that the PV based renewable system can meet the energy requirement (78.568 MWh/year) by the load in a year. Moreover, the design system can sell energy (56.065 MWh/year) back to the grid that produces extra revenue for the system owner. The economic performance parameters of the design such as payback period (10 Years), net present value (USD 120755), internal rate of return (10%), and profitability index (3.09) without considering discount rate, further proves the financial viability of the solar PV system for the SQU sports complex.

International Journal of Smart Grid and Clean Energy, 2017

This paper presents the reliability evaluation of a microgrid system considering the intermittenc... more This paper presents the reliability evaluation of a microgrid system considering the intermittency effect of renewable energy sources such as wind in this study. One of the main objectives of constructing a microgrid system is to ensure reliable power supply to loads in the microgrid. In order to achieve this objective, it is essential to evaluate the reliability of power generation of the microgrid under various uncertainties. Because highly variable wind resources and different operating modes of the microgrid are the major factors to influence the generating capacity of the microgrid in this study. Reliability models of various subsystems of a 3-MW wind generation system are developed. The subsystems include wind turbine rotor, gearbox, generator, and interfacing power electronics system. The impact of stochastically varying wind speed to generate power by the wind turbine system is accounted in developing subsystems reliability model. A Microgrid System Reliability (MSR) model is then developed by integrating the reliability models of wind turbine systems with hydro and storage units in the study microgrid system using the system reliability concept. A Monte Carlo simulation technique is utilized to implement the developed reliability models of wind generation and microgrid systems in Matlab environment. The investigation reveals that maximizing the use of wind generation systems and storage units increases the reliability of power generation of the proposed microgrid system in different operating modes.

2009 1st International Conference on the Developements in Renewable Energy Technology (ICDRET), 2009

... Bangladesh Sanjida Moury, R. Ahshan Faculty of Engineering and Applied Science, Memorial Univ... more ... Bangladesh Sanjida Moury, R. Ahshan Faculty of Engineering and Applied Science, Memorial University of Newfoundland E-mail: Sanjida.moury@mun.ca ... [4] Banglapedia (National encyclopaedia of Bangladesh) [5] MJ Khan, MT Iqbal, S. Mahboob “A wind Map of Bangladesh ...

IEEE Transactions on Industry Applications, May 1, 2014

This paper presents the implementation and performance evaluation of an embedded digital protecti... more This paper presents the implementation and performance evaluation of an embedded digital protection for three-phase (3φ) interior permanent-magnet synchronous motor (IPMSM) drives. The presented digital protection is established through extracting the high-frequency subband present in the d-q-axis components of the currents drawn by the protected IPMSM. The desired high-frequency subband is extracted using the wavelet packet transform (WPT) from the d-q-axis current components, which are obtained from the controller of the IPMSM drive. The extracted high-frequency subband contains signature information that allows detecting and classifying transient disturbances into fault and nonfault events. The presented method is insensitive to the variations in the drive parameters, loading levels, nature of electrical faults (open circuit or short circuit), and operation of the drive controller. These features of the d-q WPT-based digital protection simplify its implementation and facilitate its embedding within the controller of the IPMSM drive. The performance of the d-q WPT-based digital protection is experimentally evaluated on a laboratory 5-hp IPMSM drive for various fault and nonfault events. Test results demonstrate fast, accurate, and reliable detection, classification, and response to fault and nonfault events. Index Terms-Digital filters and real-time implementation, d-q-axis components, three-phase permanent-magnet synchronous motor drives, wavelet transforms.

IEEE Transactions on Industry Applications, Mar 1, 2023

This paper presents the development and testing of a model-predictive control (MPC) for three pha... more This paper presents the development and testing of a model-predictive control (MPC) for three phase (3phi)(3\phi)(3phi) transformerless grid-connected 5-level power electronic converters (PECs). The proposed MPC employs a discrete-time model of 5-level PECs to predict the future values of the grid-injected currents and ground potential. predicted values of the grid-injected currents and ground potential are used to set the reference signals to minimize a cost function, which is formulated in terms of the command and actual grid-injected current and ground potential. The tested MPC is implemented for transformerless grid-connected diode-clamped and flying-capacitor 5-level PECs under different conditions. Test results show that the developed MPC can operate transformerless grid-connected PECs to ensure accurate, dynamic, and fast responses to changes in the power injected into the grid. Furthermore, the tested control demonstrates a good ability to minimize ground potentials during steady-state and step changes in the power delivered to/from the grid.

IEEE Access, 2021

Permanent magnet generator (PMG)-based wind energy conversion systems (WECSs) with battery units,... more Permanent magnet generator (PMG)-based wind energy conversion systems (WECSs) with battery units, have become a popular class of distributed generation units. These distributed generation units are typically operated using various types of controllers, including droop controllers. Existing droop controllers are designed to operate grid-side dc-ac power electronic converters (PEC) to ensure stable and reliable power production by a PMG-based WECS. The employment of battery storage units (to mitigate fluctuations in the power produced by a PMG-based WECS) introduces additional considerations for the design of droop controllers. Such considerations are due to the power available from battery units that is dependent on the state-of-charge (SOC). This paper proposes adjustments in the parameters (droop constants) of the droop control (operate the the discharge PEC) based on the SOC of the battery units. These adjustments are made to further support stable and reliable power delivery of the PMG-based WECS into the point-of-common-coupling (PCC). The proposed adjustments of droop constants are evaluated using a 7.5 kW grid-connected PMG-based WECS with 3.52 kW generator-charged battery storage units. Performance tests are carried out for step changes in the active and reactive power demands, changes in the wind speed, and grid-side disturbances. Test results show that the proposed correction of the droop constants is critical for maintaining a stable, effective, and accurate power delivery by the battery units, thus supporting the voltage/frequency stability at the PCC under different operating conditions. INDEX TERMS permanent magnet generators, wind energy conversion systems, battery storage systems, droop control, and distributed generation I. INTRODUCTION A. GENERAL

This paper aims to develop models for the ground potentials in transformerless grid-connected mul... more This paper aims to develop models for the ground potentials in transformerless grid-connected multi-level power electronic converters (PECs). These PECs are widely used in photovoltaic systems, motor drives, and solid-state power transformers, where they offer reduced input and output harmonic distortions. The desired models for ground potentials are constructed based on common-mode voltages across each leg of the multi-level PECs. The constructed models for ground potentials are to be used for creating local grounding, along with designing adequate grounding circuits for transformerless grid-connected multi-level PECs. An adequate local grounding (for transformerless grid connected PEC) ensures blocking ground currents from flowing through the host grid grounding, and guarantees eliminating ground potentials. The developed models and grounding circuits are evaluated for transformerless grid-connected diode-clamped, flying-capacitor, and cascaded H-bridge multi-level PECs under different operating conditions. Test results demonstrate the significant advantages of the adequate grounding of transformerless grid-connected PECs, in terms of reduced input and output harmonic distortion, minimized ground potentials, and improved efficiency.

IEEE Transactions on Industry Applications, May 1, 2023

IEEE Transactions on Industry Applications, 2022

IEEE Access

Appropriate renewable distributed generation (RDG) placement is one of the most significant issue... more Appropriate renewable distributed generation (RDG) placement is one of the most significant issues for the efficient operation of current power systems. Since the inverter-interfaced RDG lacks rotating mass to sustain the system's inertia, microgrids have low total system inertia, which impairs frequency stability and can yield significant frequency and voltage instability in severe disruptions. The virtual synchronous generator (VSG), which uses concepts that regulate the inverter to simulate a conventional synchronous generator, is one of the most promising solutions to address these challenges. Hence, this research proposes a unique technique of simultaneous optimal solution for RDG and VSG sizing and placement in distribution networks using a recent metaheuristic technique called the Multi-objective Salp Swarm Optimization Algorithm (MOSSA). The objective function was to minimize the frequency deviation and maximize the total annual energy savings and operational costs of the RDG and VSG units. This study assesses IEEE 33 bus, 69 bus distribution network, and practical Masirah network as the test systems. Moreover, the MOSSA Pareto fronts are superior to two recent metaheuristics employed in this research domain: Multi-objective Particle Swarm Optimization (MOPSO) and Non-dominated Sorting Genetic Algorithm-II (NSGA-II). The results demonstrate that the MOSSA Pareto fronts satisfied the frequency and energy-saving objectives. In addition, all Pareto fronts accurately prevented voltage limit infringements, and the overall energy losses were significantly reduced. INDEX TERMS Virtual synchronous generator, optimization, multi-objective algorithm, renewable energy, distributed generation. NOMENCLATURE b Branch index. i Bus index. NBR Total number of branches P gen Actual power generation. P load Active demand. P loss Active loss. Q gen Reactive generation. Qr load Reactive demand. The associate editor coordinating the review of this manuscript and approving it for publication was Rajesh Kumar. Qr loss Reactive loss. S l Power transmitted in branch l. Vm bus Voltage at a certain bus. C RDG/VSG Cost per kW of injected power. S RDG/VSG,m Size of m th RDG/VSG. S RDG/VSG,max Allowable maximum size. T RDG/VSG Total RDG/VSG lifetime in years. C E Average cost of energy loss per kWh. R Rate of interest on capital investment of the installed RDG-VSG. AEL T ,RDG/VSG Total annual economic loss with RDG/VSG.

2021 IEEE Industry Applications Society Annual Meeting (IAS), Oct 10, 2021

This paper presents a method for evaluating smart grid functions that are implemented to operate ... more This paper presents a method for evaluating smart grid functions that are implemented to operate residential loads. The proposed assessment method is developed based on the energy not-served (ENS) determined at a point-of-supply feeding residential loads. Smart grid functions can operate energy storage appliances (household water heaters, air conditioners, and heating units) to store thermal energy during the daily off-peak-demand hours. The stored thermal energy is discharged during the daily peak-demand hours, thus reducing the power demands of residential loads. The differences in daily energy demands created by smart grid functions can provide an accurate assessment of the effectiveness of smart grid functions. The ENS-based method is tested for 200 residential households fed from 4 distribution transformers, and are operated by smart grid functions. In these tests, smart grid functions are implemented by the peak-demand management, direct load control, and demand response. Test results demonstrate the accuracy and simplicity of the ENS-based method to assess smart grid functions in terms of the ability to reduce the power demands of residential loads during peak-demand hours.

2022 IEEE Industry Applications Society Annual Meeting (IAS), Oct 9, 2022

Energies

Power system stability is greatly affected by two types of stochastic or random disturbances: (1)... more Power system stability is greatly affected by two types of stochastic or random disturbances: (1) topological and (2) parametric. The topological stochastic disturbances due to line faults caused by a series of lightning strikes (associated with circuit breaker, C.B., opening, and auto-reclosing) are modeled in this paper as continuous-time Markov jumps. Additionally, the stochastic parameter changes e.g., the line reactance, are influenced by the phase separation, which in turn depends on the stochastic wind speed. This is modeled as a stochastic disturbance. In this manuscript, the impact of the above stochastic disturbance on power system small-disturbance stability is studied based on stochastic differential equations (SDEs). The mean-square stabilization of such a system is conducted through a novel excitation control. The invariant ellipsoid and linear matrix inequality (LMI) optimization are used to construct the control system. The numerical simulations are presented on a mu...

International Journal of Renewable Energy Research

This paper presents the design and economic analysis of a photovoltaic (PV) system for a campus s... more This paper presents the design and economic analysis of a photovoltaic (PV) system for a campus sports complex located at the Sultan Qaboos University (SQU) in Oman. The designed PV system shows the ability to serve the total energy required by the various playgrounds in the sports complex and to sell excess power to the grid. Oman is one of the gulf countries that has the highest average solar irradiation. Besides, the temperature in Oman varies in a broad spectrum daily and seasonally. This variation in temperature, especially in a hot climate like in Oman, has a significant impact on the PV output. This paper addresses such a change of temperature in designing the PV system for the sports complex. This paper also presents the mathematical model utilized in designing the PV system and its design process in detail. The outcome of the design shows that the PV based renewable system can meet the energy requirement (78.568 MWh/year) by the load in a year. Moreover, the design system can sell energy (56.065 MWh/year) back to the grid that produces extra revenue for the system owner. The economic performance parameters of the design such as payback period (10 Years), net present value (USD 120755), internal rate of return (10%), and profitability index (3.09) without considering discount rate, further proves the financial viability of the solar PV system for the SQU sports complex.

International Journal of Smart Grid and Clean Energy, 2017

This paper presents the reliability evaluation of a microgrid system considering the intermittenc... more This paper presents the reliability evaluation of a microgrid system considering the intermittency effect of renewable energy sources such as wind in this study. One of the main objectives of constructing a microgrid system is to ensure reliable power supply to loads in the microgrid. In order to achieve this objective, it is essential to evaluate the reliability of power generation of the microgrid under various uncertainties. Because highly variable wind resources and different operating modes of the microgrid are the major factors to influence the generating capacity of the microgrid in this study. Reliability models of various subsystems of a 3-MW wind generation system are developed. The subsystems include wind turbine rotor, gearbox, generator, and interfacing power electronics system. The impact of stochastically varying wind speed to generate power by the wind turbine system is accounted in developing subsystems reliability model. A Microgrid System Reliability (MSR) model is then developed by integrating the reliability models of wind turbine systems with hydro and storage units in the study microgrid system using the system reliability concept. A Monte Carlo simulation technique is utilized to implement the developed reliability models of wind generation and microgrid systems in Matlab environment. The investigation reveals that maximizing the use of wind generation systems and storage units increases the reliability of power generation of the proposed microgrid system in different operating modes.

2009 1st International Conference on the Developements in Renewable Energy Technology (ICDRET), 2009

... Bangladesh Sanjida Moury, R. Ahshan Faculty of Engineering and Applied Science, Memorial Univ... more ... Bangladesh Sanjida Moury, R. Ahshan Faculty of Engineering and Applied Science, Memorial University of Newfoundland E-mail: Sanjida.moury@mun.ca ... [4] Banglapedia (National encyclopaedia of Bangladesh) [5] MJ Khan, MT Iqbal, S. Mahboob “A wind Map of Bangladesh ...

IEEE Transactions on Industry Applications, May 1, 2014

This paper presents the implementation and performance evaluation of an embedded digital protecti... more This paper presents the implementation and performance evaluation of an embedded digital protection for three-phase (3φ) interior permanent-magnet synchronous motor (IPMSM) drives. The presented digital protection is established through extracting the high-frequency subband present in the d-q-axis components of the currents drawn by the protected IPMSM. The desired high-frequency subband is extracted using the wavelet packet transform (WPT) from the d-q-axis current components, which are obtained from the controller of the IPMSM drive. The extracted high-frequency subband contains signature information that allows detecting and classifying transient disturbances into fault and nonfault events. The presented method is insensitive to the variations in the drive parameters, loading levels, nature of electrical faults (open circuit or short circuit), and operation of the drive controller. These features of the d-q WPT-based digital protection simplify its implementation and facilitate its embedding within the controller of the IPMSM drive. The performance of the d-q WPT-based digital protection is experimentally evaluated on a laboratory 5-hp IPMSM drive for various fault and nonfault events. Test results demonstrate fast, accurate, and reliable detection, classification, and response to fault and nonfault events. Index Terms-Digital filters and real-time implementation, d-q-axis components, three-phase permanent-magnet synchronous motor drives, wavelet transforms.

IEEE Transactions on Industry Applications, Mar 1, 2023

This paper presents the development and testing of a model-predictive control (MPC) for three pha... more This paper presents the development and testing of a model-predictive control (MPC) for three phase (3phi)(3\phi)(3phi) transformerless grid-connected 5-level power electronic converters (PECs). The proposed MPC employs a discrete-time model of 5-level PECs to predict the future values of the grid-injected currents and ground potential. predicted values of the grid-injected currents and ground potential are used to set the reference signals to minimize a cost function, which is formulated in terms of the command and actual grid-injected current and ground potential. The tested MPC is implemented for transformerless grid-connected diode-clamped and flying-capacitor 5-level PECs under different conditions. Test results show that the developed MPC can operate transformerless grid-connected PECs to ensure accurate, dynamic, and fast responses to changes in the power injected into the grid. Furthermore, the tested control demonstrates a good ability to minimize ground potentials during steady-state and step changes in the power delivered to/from the grid.

IEEE Access, 2021

Permanent magnet generator (PMG)-based wind energy conversion systems (WECSs) with battery units,... more Permanent magnet generator (PMG)-based wind energy conversion systems (WECSs) with battery units, have become a popular class of distributed generation units. These distributed generation units are typically operated using various types of controllers, including droop controllers. Existing droop controllers are designed to operate grid-side dc-ac power electronic converters (PEC) to ensure stable and reliable power production by a PMG-based WECS. The employment of battery storage units (to mitigate fluctuations in the power produced by a PMG-based WECS) introduces additional considerations for the design of droop controllers. Such considerations are due to the power available from battery units that is dependent on the state-of-charge (SOC). This paper proposes adjustments in the parameters (droop constants) of the droop control (operate the the discharge PEC) based on the SOC of the battery units. These adjustments are made to further support stable and reliable power delivery of the PMG-based WECS into the point-of-common-coupling (PCC). The proposed adjustments of droop constants are evaluated using a 7.5 kW grid-connected PMG-based WECS with 3.52 kW generator-charged battery storage units. Performance tests are carried out for step changes in the active and reactive power demands, changes in the wind speed, and grid-side disturbances. Test results show that the proposed correction of the droop constants is critical for maintaining a stable, effective, and accurate power delivery by the battery units, thus supporting the voltage/frequency stability at the PCC under different operating conditions. INDEX TERMS permanent magnet generators, wind energy conversion systems, battery storage systems, droop control, and distributed generation I. INTRODUCTION A. GENERAL

This paper aims to develop models for the ground potentials in transformerless grid-connected mul... more This paper aims to develop models for the ground potentials in transformerless grid-connected multi-level power electronic converters (PECs). These PECs are widely used in photovoltaic systems, motor drives, and solid-state power transformers, where they offer reduced input and output harmonic distortions. The desired models for ground potentials are constructed based on common-mode voltages across each leg of the multi-level PECs. The constructed models for ground potentials are to be used for creating local grounding, along with designing adequate grounding circuits for transformerless grid-connected multi-level PECs. An adequate local grounding (for transformerless grid connected PEC) ensures blocking ground currents from flowing through the host grid grounding, and guarantees eliminating ground potentials. The developed models and grounding circuits are evaluated for transformerless grid-connected diode-clamped, flying-capacitor, and cascaded H-bridge multi-level PECs under different operating conditions. Test results demonstrate the significant advantages of the adequate grounding of transformerless grid-connected PECs, in terms of reduced input and output harmonic distortion, minimized ground potentials, and improved efficiency.

IEEE Transactions on Industry Applications, May 1, 2023

IEEE Transactions on Industry Applications, 2022

Wind turbine simulator is an effective tool to evaluate wind energy conversion systems control. D... more Wind turbine simulator is an effective tool to evaluate wind energy conversion systems control. Due to random variation in wind speed, it is difficult to develop and improve the control mechanism for a successful wind energy conversion system while wind turbine is in a wind field. To achieve this aim, a wind turbine simulator has been proposed and initial development has been performed in the energy systems lab at MUN. This paper describes the developed small induction generator based wind turbine simulator. The wind turbine simulator consists of a computer controlled dc motor, a three-phase induction generator, interfacing I/O card, instrumentation for voltage, current, torque and speed measurements. The DC motor is controlled in such a way that its shaft behaves as a wind turbine rotor in the wind. A parameter optimized discrete PI controller has designed to control the torque of the dc motor. The controller also makes sure that the actual rotational speed of the motor is same as that of wind turbine rotor. This paper describes the operating principles, theoretical explanations and some test results of the developed simulator. This simulator will be used to develop and test controllers for a small induction generator based wind energy conversion system.