Satabdy Jena | NIT Meghalaya (original) (raw)

Papers by Satabdy Jena

2017 14th IEEE India Council International Conference (INDICON), 2017

The large-scale world-wide adoption of Electric Vehicles as a mode of transportation is predicted... more The large-scale world-wide adoption of Electric Vehicles as a mode of transportation is predicted to create stress on the already loaded power supply network. As such continued efforts in the area of distributed generation assisted charging stations are in full-swing. The paper investigates the outcomes of utilizing a PV assisted Battery Swapping Station to combat and alleviate simultaneously the issues of overburden and energy storage. A BSS can be tethered not only to provide battery swapping services to EVs but also provide for grid support, energy storage, ancillary services, etc. A grid interfaced PV assisted BSS system and its functioning in the smart grid environment has been proposed considering the system has a reliable and secure communication infrastructure. The multiple roles of the BSS and its coordinated functioning with the PV and the grid is examined under various test scenarios. The hardware prototyping of the control strategies for the inverter and the BSS is realized using Virtex-6 FPGA ML605 evaluation kit. The simulation and the hardware co-simulation results are presented to validate the efficacy of the proposed control scheme.

International Journal of Circuit Theory and Applications, 2018

The large scale penetration of renewable energy resources has boosted the need of using improved ... more The large scale penetration of renewable energy resources has boosted the need of using improved control technique and modular power electronic converter structures for efficient and reliable operation of grid-connected systems. This study investigates the performance of a grid-connected 3-phase 3-level neutral-point clamped voltage source inverter for renewable energy integration by using improved current control technique. For medium or high-voltage grid interfacing, the multilevel inverter structure is generally used to reduce the voltage stress across the switching device as well as the harmonic distortion. The neutral-point clamped voltage source inverter is controlled by using decoupling technique along with the proper grid synchronization via moving average filter-based phase-locked loop. The moving average filter-based phase-locked loop is used to reduce the delay in grid angle estimation under balanced as well as distorted grid conditions. A Lyapunov-based approach for analysing the stability of the system has also been discussed. In this study, the hardware-in-loop (HIL) simulation of the control algorithm and the grid synchronization technique is realized using Virtex-6 FPGA ML605 evaluation kit. The performance of the system is analyzed by conducting a time-domain simulation in the Matlab/Simulink platform and its performance is examined in the HIL environment. The simulation and the hardware cosimulation results are presented to validate the effectiveness of the proposed control scheme. KEYWORDS field programmable gate array (FPGA), moving average filter (MAF), photovoltaic (PV), phase-locked loop (PLL), two-degree-of-freedom (2DoF)

2016 IEEE Region 10 Conference (TENCON), 2016

Small-scale distributed energy systems possess the potential to meet local demand of power as wel... more Small-scale distributed energy systems possess the potential to meet local demand of power as well as feed the excess power to the grid. In such grid-tied systems, it is necessary to ensure the reliable tripping of grid-interfaced inverters whenever the grid is unintentionally disconnected. As such, anti-islanding protection schemes are crucial for grid-interfaced Distributed Generation (DG) systems which assure the safety of critical loads, devices and personnel. This paper evaluates the implementation of various FPGA based passive anti-islanding protection schemes and their comparative performance. The synchronization of the DG inverter with the grid is ensured with aMoving Average Filter based Phase Locked Loop (MAF-PLL). The filter also aids for providing an input to the Over/Under Frequency and the Rate of Change of Frequency (ROCOF) protection techniques that has been employed for protection against events of islanding in the DG system. The dc-link capacitor voltage is a reflection of the active power exchange at the Point of Common Coupling (PCC) and hence any mismatch at the PCC causes the dc-link voltage to fluctuate. An over and under voltage protection scheme at the PCC has also been used. The schemes are tested in simulation as well as hardware co-simulation environment to validate their functioning.

2016 IEEE 6th International Conference on Power Systems (ICPS), 2016

The state-of-art in research practices across the globe emphasizes the real-time implementation o... more The state-of-art in research practices across the globe emphasizes the real-time implementation of the control techniques. This paper investigates the performance of an Field Programmable Gate Array (FPGA)-based real-time implementation of a three-phase three-level Voltage Source Inverter (VSI) for grid integration of multi-string PV array. FPGA-based prototyping of control circuits enables the study of sensitivity on parameters variations, increases the safety and reduces the time and costs of implementation. The proposed system consists of a centralized multilevel inverter that aids in the conversion of DC power obtained from a multi-string PV array to AC power, which is fed to the utility grid as well as the three phase local loads connected at the Point of Common Coupling (PCC). The multilevel structure finds use in handling large amount of power, reducing voltage stress across the semi-conductor devices and reducing the harmonic distortion. The system is developed in Matlab/Simulink environment and the control algorithm of the VSI is implemented in Virtex-6 ML605 Evaluation-Kit with Xilinx System Generator providing the effective grid-interfacing environment.

2022 IEEE 10th Power India International Conference (PIICON)

2022 IEEE Global Conference on Computing, Power and Communication Technologies (GlobConPT)

2019 National Power Electronics Conference (NPEC)

A distributed secondary control based on consensus algorithm containing voltage synchronization a... more A distributed secondary control based on consensus algorithm containing voltage synchronization and improvised optimizer modules is established along with a primary reverse droop controller to ameliorate the operation of shunt DC electric springs (DC-ES) in a typical DC microgrid cluster. These networked DC-ESs in the clusters, employed for voltage compensation and power balancing, are interconnected via a sparse communication layer. A low voltage DC microgrid is considered in this paper with boost converters for PV arrays emulating constant power sources, synchronous buck converters for DC-ESs and mix of resistance and constant power loads to assess the functioning of the proposed control philosophy for the DC-ES. The unified operation of compensating the DC bus voltage and simultaneously operating every DC spring at its own optimal operating point on the cost-generation characteristic curve aids to minimize the associated costs. In this work, the current contribution from each shunt compensator in the DC microgrid is correlated with its optimal operating point. To circumvent the case wherein any of the DC-ESs disregards its upper and lower boundaries, they are assumed to be graphically disconnected and the rest operate for achieving consensus in their respective incremental costs; provided the system incremental cost achieved via consensus is acceptable. With the aforementioned framework, the work presented herein investigates the operation of the radial DC network under physical and cyber adversities.

2019 8th International Conference on Power Systems (ICPS)

This paper investigates the performance assessment of droop controlled converters in a low inerti... more This paper investigates the performance assessment of droop controlled converters in a low inertia, low voltage DC microgrid scenario. It employs a generalized DC distribution network consisting of both current-controlled and voltage-controlled voltage source converters and a mix of constant impedance, constant current and constant power loads. Since in large distribution networks, lack of inertia is the cause of instability, virtual impedance based methods and capacitor control techniques have been proposed. A RC-based droop control strategy is employed in this work in order to impart inertia to the system thereby improving the transient performance of the network. The converters considered are both grid-feeding and grid-forming in order to analyze the response in the presence of dissimilar electrical energy sources. The grid-feeding converters, both voltage and current-controlled, are interconnected via communication layer and are governed by the consensus laws for multi-agent systems. The networked control systems aids in achieving proper load current sharing and desired voltage regulation. This is essential for the operation of critical loads. The study presents a comparative assessment of the response of RC-droop and conventional droop in the varied microgrid conditions. The cyber-physical system is modeled in MATLAB/Simulink and tested against various operating situations and cyber adversities to test the efficacy of the control law.

2019 IEEE Power & Energy Society General Meeting (PESGM), 2019

A distributed control paradigm based on reverse droop primary controller is established to formul... more A distributed control paradigm based on reverse droop primary controller is established to formulate a control framework for the problem of achieving voltage regulation and proportionate load current sharing in a DC microgrid scenario. It utilizes the hierarchical control approach to form a cyber-physical interaction layer of the DC distribution system. The adjustment/correction factors for the DC voltage is generated by the secondary control layer wherein the voltage and current observers process the neighboring agents' dataset to effectively regulate the DC voltage. The proposed control achieves faster dynamics as compared to a conventional V-I droop controller thereby enabling improved transient and steady state dynamics. The controller is subjected to various test cases like plug-n-play capability, switched networks, remote and local load changes, resiliency to communication delays, etc. in order to investigate its robustness to disturbances and uncertainties. A low voltage DC microgrid test-bench with underlying buck converters with dispatchable energy source inputs is employed to validate the aforementioned features. The paper considers the functioning of the microgrid test-bench under various load dynamics such as constant power loads (CPLs) and resistive loads.

2020 IEEE Power & Energy Society General Meeting (PESGM), 2020

In this paper, the authors have attempted to address the problem of power sharing in networked hy... more In this paper, the authors have attempted to address the problem of power sharing in networked hybrid AC/DC micro-grid clusters by utilising back-to-back converter. The hierarchical distributed cooperative control strategy is employed for both the AC and DC microgrid clusters (intra-microgrid control) and an inter-microgrid control strategy employing back-to-back converter for enabling power sharing among the clusters according to the required needs. The distributed secondary control for both the AC and DC MGs aid to reprimand the voltage drops due to presence of cable resistance and droop characteristics. It thus helps to achieve a regulated voltage at both the AC and DC PCC. Particularly in AC MG, it enhances the voltage and power quality. Further, it is worth noting that most of the consensus algorithms are asymptotically convergent and hence in order to achieve finite-time convergence, a modified consensus approach is used for the DC microgrid cluster. This is done to achieve faster consensus irrespective of the unforeseen disturbance / transients that may occur in the AC microgrid clusters. The distributed dynamic averaging consensus algorithm based on PI controllers (DAC-PI) is also investigated for robustness against physical and communication failures. With the proposed inter and intra-microgrid cluster control mechanism, power balance between three phase AC MGs and DC MG is illustrated in this work. This could be utilised as practical applications in stand-alone microgrids, marine power systems, more electric aircraft power systems and can be equipped with mode selection algorithms to enable connection to the utility thereby endowing flexibility and reliability to the network of microgrid clusters. Extensive simulations of test-cases are provided with MATLAB/Simpowersystems platform to elucidate the performance of the proposed control strategy and the hybrid infrastructure.

2020 IEEE International Conference on Power Electronics, Smart Grid and Renewable Energy (PESGRE2020), 2020

The work presented investigates the dynamics of a reverse droop current controller and a conventi... more The work presented investigates the dynamics of a reverse droop current controller and a conventional droop voltage controller in a distributed cooperative secondary control environment operating with the consensus aided communication network for a 5-bus DC microgrid (MG). The microgrid system considered has multiple distributed energy resources (DER) i.e. photovoltaic array and battery connected to 4 buses while the last bus serves as an interconnection for a remote load terminal. This aids in bolstering the performance analysis of the aforementioned controllers under various operating scenarios like switching networks, delay, plug-n-play, etc. The current dynamics being faster than the voltage dynamics, a single current controller could be employed instead of voltage controller or a cascaded voltage-current controller for reducing system complexity and achieving faster convergence. A low voltage DC microgrid test-system (48 V) assuming (semi) dispatchable energy sources at its inp...

2020 IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES), 2020

The uncertainties caused by renewable energy sources (RESs), droop control, etc. often undermine ... more The uncertainties caused by renewable energy sources (RESs), droop control, etc. often undermine the performance of distributed DC microgrids. In this paper, we have investigated the functioning of a novel consensus-based secondary control strategy to achieve proportionate current sharing and voltage synchrony in a generalized networked multiple DC microgrid clusters with hybrid energy storage system (HESS) by compensating mismatches in droop coefficients, line resistances, etc. Alongside, frequency based power sharing and voltage regulation is achieved in a decentralized manner to circumvent load transitions. An optimal, event-based communication strategy has been designed for the sharing of state information with neighboring converters over limited bandwidth. Design procedure, stability analysis, performance under communication adversities are provided to help determine the suitability of the proposed technique. Finally, simulation results for different test-cases are presented to validate the efficacy and robustness of the proposed method.

The issue of EVs to be parked for longer hours depending on the nature of the charger may lead to... more The issue of EVs to be parked for longer hours depending on the nature of the charger may lead to overcrowding and stranding of vehicles at charging stations which can be eliminated by the realization of a Battery Swapping Station at which a vehicle's discharged battery pack can be immediately swapped for a fully charged one, eliminating the delay involved in waiting. The dependency of the BSS on the weak grid for charging can be alleviated by providing a renewable energy input and thus pave the way for DG assisted charging stations. The unnecessary loading on the electrical infrastructure can thus be avoided. The study pertains to the ancillary services of a BSS under different situations of power deficit. A 2-Degree-of-freedom based inverter current and voltage cascaded control is also introduced for faster set-point tracking. Extensive simualtions were performed in Matlab/Simulink to validate the efficacy of a grid interfaced PV along with BSS to address power void issues.

Balancing the rift between demand and production of energy has become one of the major growing co... more Balancing the rift between demand and production of energy has become one of the major growing concerns globally. This has prompted the technocrats, policy-makers, etc. to contemplate on the potency of renewable energy (RES) sources. The outcome has resulted in the world-wide adoption of RES to meet energy deficits. However various grid codes govern their integration to the grid. These monitor the functioning of the RES power converters and impose active and reactive power injection requirements. This is termed as the low voltage ride-through capability of the power converters in order to ensure unnecessary tripping of the interfacing converter resulting in sudden demand-shift on the conventional sources. Cascaded failures and blackouts could be an immediate result. Furthermore proper, fast and dynamic tracking and synchronization of the grid angle also emerges as a necessity in order to respond to the scenario of sudden grid disconnection. But the vulnerability of the grid-interfac...

IEEE Systems Journal

In this article, we propose a novel, model-independent, unified detection strategy based on disag... more In this article, we propose a novel, model-independent, unified detection strategy based on disagreement Laplacian potential for effective identification of cyber anomalies in interconnected autonomous direct current (dc) microgrid (MG) clusters. This interconnection enables inter and intra-microgrid power exchange between them, thereby rendering efficient and maximum utilisation of the distributed energy resources. However, these clusters are vulnerable to cyber intrusion that disrupt the power sharing schemes. As such, we have investigated the effect of false data injections at various vulnerable points, including both voltage and current sensors in primary, and data transmission points in the distributed secondary, local, and global tertiary layers. Simultaneously, a logical evaluation in the form of data-integrity indices are formulated from the outcomes of the proposed detection scheme to provide for their timely mitigation. Ultimately a fault-ride through operation of the converters is achieved instead of alienating the misbehaving component, unlike previously reported works.

IEEE PEDES 2020, 2020

The uncertainties caused by renewable energy sources (RESs), droop control, etc. often undermine ... more The uncertainties caused by renewable energy sources (RESs), droop control, etc. often undermine the performance of distributed DC microgrids. In this paper, we have investigated the functioning of a novel consensus-based secondary control strategy to achieve proportionate current sharing and voltage synchrony in a generalized networked multiple DC microgrid clusters with hybrid energy storage system (HESS) by compensating mismatches in droop coefficients,line resistances,etc. Alongside, frequency based power sharing and voltage regulation is achieved in a decentralized manner to circumvent load transitions. An optimal, event-based communication strategy has been designed for the sharing of state information with neighboring converters over limited bandwidth. Design procedure, stability analysis, performance under communication adversities are provided to help determine the suitability of the proposed technique. Finally, simulation results for different test-cases are presented to validate the efficacy and robustness of the proposed method.

IEEE PESGM 2020, 2020

In this paper, the authors have attempted to address the problem of power sharing in networked hy... more In this paper, the authors have attempted to address the problem of power sharing in networked hybrid AC/DC micro-grid clusters by utilising back-to-back converter. The hierarchical distributed cooperative control strategy is employed for both the AC and DC microgrid clusters (intra-microgrid control) and an inter-microgrid control strategy employing back-to-back converter for enabling power sharing among the clusters according to the required needs. The distributed secondary control for both the AC and DC MGs aid to reprimand the voltage drops due to presence of cable resistance and droop characteristics. It thus helps to achieve a regulated voltage at both the AC and DC PCC. Particularly in AC MG, it enhances the voltage and power quality. Further, it is worth noting that most of the consensus algorithms are asymptotically convergent and hence in order to achieve finite-time convergence, a modified consensus approach is used for the DC microgrid cluster. This is done to achieve faster consensus irrespective of the unforeseen disturbance / transients that may occur in the AC microgrid clusters. The distributed dynamic averaging consensus algorithm based on PI controllers (DAC-PI) is also investigated for robustness against physical and communication failures. With the proposed inter and intra-microgrid cluster control mechanism, power balance between three phase AC MGs and DC MG is illustrated in this work. This could be utilised as practical applications in stand-alone microgrids, marine power systems, more electric aircraft power systems and can be equipped with mode selection algorithms to enable connection to the utility thereby endowing flexibility and reliability to the network of microgrid clusters. Extensive simulations of test-cases are provided with MATLAB/Simpowersystems platform to elucidate the performance of the proposed control strategy and the hybrid infrastructure.

PESGRE, 2020

The work presented investigates the dynamics of a reverse droop current controller and a conventi... more The work presented investigates the dynamics of a reverse droop current controller and a conventional droop voltage controller in a distributed cooperative secondary control environment operating with the consensus aided communication network for a 5-bus DC microgrid (MG). The microgrid system considered has multiple distributed energy resources (DER) i.e. photovoltaic array and battery connected to 4 buses while the last bus serves as an interconnection for a remote load terminal. This aids in bolstering the performance analysis of the aforementioned controllers under various operating scenarios like switching networks, delay, plug-n-play,etc. The current dynamics being faster than the voltage dynamics, a single current controller could be employed instead of voltage controller or a cascaded voltage-current controller for reducing system complexity and achieving faster convergence. A low voltage DC microgrid test-system (48 V) assuming (semi) dispatchable energy sources at its inputs catering to local and remote resistive & constant power loads is considered in the study to investigate and validate the controllers' transient responses. Index Terms-Muti-agent systems (MAS),hierarchical control, reverse droop, sliding mode control (SMC), constant power load (CPL). I. INTRODUCTION Distributed control employing cooperative networks being the cynosure of research in parallel multi-converter systems continues to intrigue the intellect and presents ample problem statements to be embarked upon. The centre-flocking and collision avoiding features of animals and birds,natural phenomena like thermodynamic laws, insect swarming, flocking of birds, phase transitions etc. in physical, chemical and biological processes, etc. were studied using consensus algorithms and later correlated to multi-agent systems, communication networks[1],[2] which endow mobility to control decisions via exchange of information among agents in accordance with the designed or inherent communication protocols. These laws were then further extended to microgrids (MGs) realizing its strong potential for the correction of the flaws that arise owing to the line impedances superimposing the effect of droop control using virtual impedances for accurate load current sharing in DC and AC parallel multi-converter systems[3]-[6] and to eliminate single-point-of-failure and ameliorate high communication channel bandwidth requirements on account of centralized communication infrastructure.This symbiosis of electrical properties and communication networks commonly known as networked multi-agent systems (MAS) have garnered legit attention owing to their flexibility ,scalability and computational efficiency [7]. It also presents the concept of independent, mobile, distributed agents (controllers) that could take decisions of their own by processing information of their nearest agents (controllers). Tracking and synchronization of these agents are the broad classifications in the distributed control theory [8], wherein it concerns leaderless and leader configurations respectively. It is noteworthy to mention that the sudden inclination towards DC distribution systems reverberated on account of its supremacy over AC supply for not including issues related to power quality, avoiding multiple stages of conversion, enhanced efficiency, higher renewable penetration (DC in nature),etc. The multifaceted benefits

ICPS, 2019

This paper investigates the performance assessment of droop controlled converters in a low inerti... more This paper investigates the performance assessment of droop controlled converters in a low inertia, low voltage DC microgrid scenario. It employs a generalized DC distribution network consisting of both current-controlled and voltage-controlled voltage source converters and a mix of constant impedance, constant current and constant power loads. Since in large distribution networks, lack of inertia is the cause of instability, virtual impedance based methods and capacitor control techniques have been proposed. A RC-based droop control strategy is employed in this work in order to impart inertia to the system thereby improving the transient performance of the network. The converters considered are both grid-feeding and grid-forming in order to analyze the response in the presence of dissimilar electrical energy sources. The grid-feeding converters, both voltage and current-controlled, are interconnected via communication layer and are governed by the consensus laws for multi-agent systems. The networked control systems aids in achieving proper load current sharing and desired voltage regulation. This is essential for the operation of critical loads. The study presents a comparative assessment of the response of RC-droop and conventional droop in the varied microgrid conditions. The cyber-physical system is modeled in MATLAB/Simulink and tested against various operating situations and cyber adversities to test the efficacy of the control law.

2017 14th IEEE India Council International Conference (INDICON), 2017

The large-scale world-wide adoption of Electric Vehicles as a mode of transportation is predicted... more The large-scale world-wide adoption of Electric Vehicles as a mode of transportation is predicted to create stress on the already loaded power supply network. As such continued efforts in the area of distributed generation assisted charging stations are in full-swing. The paper investigates the outcomes of utilizing a PV assisted Battery Swapping Station to combat and alleviate simultaneously the issues of overburden and energy storage. A BSS can be tethered not only to provide battery swapping services to EVs but also provide for grid support, energy storage, ancillary services, etc. A grid interfaced PV assisted BSS system and its functioning in the smart grid environment has been proposed considering the system has a reliable and secure communication infrastructure. The multiple roles of the BSS and its coordinated functioning with the PV and the grid is examined under various test scenarios. The hardware prototyping of the control strategies for the inverter and the BSS is realized using Virtex-6 FPGA ML605 evaluation kit. The simulation and the hardware co-simulation results are presented to validate the efficacy of the proposed control scheme.

International Journal of Circuit Theory and Applications, 2018

The large scale penetration of renewable energy resources has boosted the need of using improved ... more The large scale penetration of renewable energy resources has boosted the need of using improved control technique and modular power electronic converter structures for efficient and reliable operation of grid-connected systems. This study investigates the performance of a grid-connected 3-phase 3-level neutral-point clamped voltage source inverter for renewable energy integration by using improved current control technique. For medium or high-voltage grid interfacing, the multilevel inverter structure is generally used to reduce the voltage stress across the switching device as well as the harmonic distortion. The neutral-point clamped voltage source inverter is controlled by using decoupling technique along with the proper grid synchronization via moving average filter-based phase-locked loop. The moving average filter-based phase-locked loop is used to reduce the delay in grid angle estimation under balanced as well as distorted grid conditions. A Lyapunov-based approach for analysing the stability of the system has also been discussed. In this study, the hardware-in-loop (HIL) simulation of the control algorithm and the grid synchronization technique is realized using Virtex-6 FPGA ML605 evaluation kit. The performance of the system is analyzed by conducting a time-domain simulation in the Matlab/Simulink platform and its performance is examined in the HIL environment. The simulation and the hardware cosimulation results are presented to validate the effectiveness of the proposed control scheme. KEYWORDS field programmable gate array (FPGA), moving average filter (MAF), photovoltaic (PV), phase-locked loop (PLL), two-degree-of-freedom (2DoF)

2016 IEEE Region 10 Conference (TENCON), 2016

Small-scale distributed energy systems possess the potential to meet local demand of power as wel... more Small-scale distributed energy systems possess the potential to meet local demand of power as well as feed the excess power to the grid. In such grid-tied systems, it is necessary to ensure the reliable tripping of grid-interfaced inverters whenever the grid is unintentionally disconnected. As such, anti-islanding protection schemes are crucial for grid-interfaced Distributed Generation (DG) systems which assure the safety of critical loads, devices and personnel. This paper evaluates the implementation of various FPGA based passive anti-islanding protection schemes and their comparative performance. The synchronization of the DG inverter with the grid is ensured with aMoving Average Filter based Phase Locked Loop (MAF-PLL). The filter also aids for providing an input to the Over/Under Frequency and the Rate of Change of Frequency (ROCOF) protection techniques that has been employed for protection against events of islanding in the DG system. The dc-link capacitor voltage is a reflection of the active power exchange at the Point of Common Coupling (PCC) and hence any mismatch at the PCC causes the dc-link voltage to fluctuate. An over and under voltage protection scheme at the PCC has also been used. The schemes are tested in simulation as well as hardware co-simulation environment to validate their functioning.

2016 IEEE 6th International Conference on Power Systems (ICPS), 2016

The state-of-art in research practices across the globe emphasizes the real-time implementation o... more The state-of-art in research practices across the globe emphasizes the real-time implementation of the control techniques. This paper investigates the performance of an Field Programmable Gate Array (FPGA)-based real-time implementation of a three-phase three-level Voltage Source Inverter (VSI) for grid integration of multi-string PV array. FPGA-based prototyping of control circuits enables the study of sensitivity on parameters variations, increases the safety and reduces the time and costs of implementation. The proposed system consists of a centralized multilevel inverter that aids in the conversion of DC power obtained from a multi-string PV array to AC power, which is fed to the utility grid as well as the three phase local loads connected at the Point of Common Coupling (PCC). The multilevel structure finds use in handling large amount of power, reducing voltage stress across the semi-conductor devices and reducing the harmonic distortion. The system is developed in Matlab/Simulink environment and the control algorithm of the VSI is implemented in Virtex-6 ML605 Evaluation-Kit with Xilinx System Generator providing the effective grid-interfacing environment.

2022 IEEE 10th Power India International Conference (PIICON)

2022 IEEE Global Conference on Computing, Power and Communication Technologies (GlobConPT)

2019 National Power Electronics Conference (NPEC)

A distributed secondary control based on consensus algorithm containing voltage synchronization a... more A distributed secondary control based on consensus algorithm containing voltage synchronization and improvised optimizer modules is established along with a primary reverse droop controller to ameliorate the operation of shunt DC electric springs (DC-ES) in a typical DC microgrid cluster. These networked DC-ESs in the clusters, employed for voltage compensation and power balancing, are interconnected via a sparse communication layer. A low voltage DC microgrid is considered in this paper with boost converters for PV arrays emulating constant power sources, synchronous buck converters for DC-ESs and mix of resistance and constant power loads to assess the functioning of the proposed control philosophy for the DC-ES. The unified operation of compensating the DC bus voltage and simultaneously operating every DC spring at its own optimal operating point on the cost-generation characteristic curve aids to minimize the associated costs. In this work, the current contribution from each shunt compensator in the DC microgrid is correlated with its optimal operating point. To circumvent the case wherein any of the DC-ESs disregards its upper and lower boundaries, they are assumed to be graphically disconnected and the rest operate for achieving consensus in their respective incremental costs; provided the system incremental cost achieved via consensus is acceptable. With the aforementioned framework, the work presented herein investigates the operation of the radial DC network under physical and cyber adversities.

2019 8th International Conference on Power Systems (ICPS)

This paper investigates the performance assessment of droop controlled converters in a low inerti... more This paper investigates the performance assessment of droop controlled converters in a low inertia, low voltage DC microgrid scenario. It employs a generalized DC distribution network consisting of both current-controlled and voltage-controlled voltage source converters and a mix of constant impedance, constant current and constant power loads. Since in large distribution networks, lack of inertia is the cause of instability, virtual impedance based methods and capacitor control techniques have been proposed. A RC-based droop control strategy is employed in this work in order to impart inertia to the system thereby improving the transient performance of the network. The converters considered are both grid-feeding and grid-forming in order to analyze the response in the presence of dissimilar electrical energy sources. The grid-feeding converters, both voltage and current-controlled, are interconnected via communication layer and are governed by the consensus laws for multi-agent systems. The networked control systems aids in achieving proper load current sharing and desired voltage regulation. This is essential for the operation of critical loads. The study presents a comparative assessment of the response of RC-droop and conventional droop in the varied microgrid conditions. The cyber-physical system is modeled in MATLAB/Simulink and tested against various operating situations and cyber adversities to test the efficacy of the control law.

2019 IEEE Power & Energy Society General Meeting (PESGM), 2019

A distributed control paradigm based on reverse droop primary controller is established to formul... more A distributed control paradigm based on reverse droop primary controller is established to formulate a control framework for the problem of achieving voltage regulation and proportionate load current sharing in a DC microgrid scenario. It utilizes the hierarchical control approach to form a cyber-physical interaction layer of the DC distribution system. The adjustment/correction factors for the DC voltage is generated by the secondary control layer wherein the voltage and current observers process the neighboring agents' dataset to effectively regulate the DC voltage. The proposed control achieves faster dynamics as compared to a conventional V-I droop controller thereby enabling improved transient and steady state dynamics. The controller is subjected to various test cases like plug-n-play capability, switched networks, remote and local load changes, resiliency to communication delays, etc. in order to investigate its robustness to disturbances and uncertainties. A low voltage DC microgrid test-bench with underlying buck converters with dispatchable energy source inputs is employed to validate the aforementioned features. The paper considers the functioning of the microgrid test-bench under various load dynamics such as constant power loads (CPLs) and resistive loads.

2020 IEEE Power & Energy Society General Meeting (PESGM), 2020

In this paper, the authors have attempted to address the problem of power sharing in networked hy... more In this paper, the authors have attempted to address the problem of power sharing in networked hybrid AC/DC micro-grid clusters by utilising back-to-back converter. The hierarchical distributed cooperative control strategy is employed for both the AC and DC microgrid clusters (intra-microgrid control) and an inter-microgrid control strategy employing back-to-back converter for enabling power sharing among the clusters according to the required needs. The distributed secondary control for both the AC and DC MGs aid to reprimand the voltage drops due to presence of cable resistance and droop characteristics. It thus helps to achieve a regulated voltage at both the AC and DC PCC. Particularly in AC MG, it enhances the voltage and power quality. Further, it is worth noting that most of the consensus algorithms are asymptotically convergent and hence in order to achieve finite-time convergence, a modified consensus approach is used for the DC microgrid cluster. This is done to achieve faster consensus irrespective of the unforeseen disturbance / transients that may occur in the AC microgrid clusters. The distributed dynamic averaging consensus algorithm based on PI controllers (DAC-PI) is also investigated for robustness against physical and communication failures. With the proposed inter and intra-microgrid cluster control mechanism, power balance between three phase AC MGs and DC MG is illustrated in this work. This could be utilised as practical applications in stand-alone microgrids, marine power systems, more electric aircraft power systems and can be equipped with mode selection algorithms to enable connection to the utility thereby endowing flexibility and reliability to the network of microgrid clusters. Extensive simulations of test-cases are provided with MATLAB/Simpowersystems platform to elucidate the performance of the proposed control strategy and the hybrid infrastructure.

2020 IEEE International Conference on Power Electronics, Smart Grid and Renewable Energy (PESGRE2020), 2020

The work presented investigates the dynamics of a reverse droop current controller and a conventi... more The work presented investigates the dynamics of a reverse droop current controller and a conventional droop voltage controller in a distributed cooperative secondary control environment operating with the consensus aided communication network for a 5-bus DC microgrid (MG). The microgrid system considered has multiple distributed energy resources (DER) i.e. photovoltaic array and battery connected to 4 buses while the last bus serves as an interconnection for a remote load terminal. This aids in bolstering the performance analysis of the aforementioned controllers under various operating scenarios like switching networks, delay, plug-n-play, etc. The current dynamics being faster than the voltage dynamics, a single current controller could be employed instead of voltage controller or a cascaded voltage-current controller for reducing system complexity and achieving faster convergence. A low voltage DC microgrid test-system (48 V) assuming (semi) dispatchable energy sources at its inp...

2020 IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES), 2020

The uncertainties caused by renewable energy sources (RESs), droop control, etc. often undermine ... more The uncertainties caused by renewable energy sources (RESs), droop control, etc. often undermine the performance of distributed DC microgrids. In this paper, we have investigated the functioning of a novel consensus-based secondary control strategy to achieve proportionate current sharing and voltage synchrony in a generalized networked multiple DC microgrid clusters with hybrid energy storage system (HESS) by compensating mismatches in droop coefficients, line resistances, etc. Alongside, frequency based power sharing and voltage regulation is achieved in a decentralized manner to circumvent load transitions. An optimal, event-based communication strategy has been designed for the sharing of state information with neighboring converters over limited bandwidth. Design procedure, stability analysis, performance under communication adversities are provided to help determine the suitability of the proposed technique. Finally, simulation results for different test-cases are presented to validate the efficacy and robustness of the proposed method.

The issue of EVs to be parked for longer hours depending on the nature of the charger may lead to... more The issue of EVs to be parked for longer hours depending on the nature of the charger may lead to overcrowding and stranding of vehicles at charging stations which can be eliminated by the realization of a Battery Swapping Station at which a vehicle's discharged battery pack can be immediately swapped for a fully charged one, eliminating the delay involved in waiting. The dependency of the BSS on the weak grid for charging can be alleviated by providing a renewable energy input and thus pave the way for DG assisted charging stations. The unnecessary loading on the electrical infrastructure can thus be avoided. The study pertains to the ancillary services of a BSS under different situations of power deficit. A 2-Degree-of-freedom based inverter current and voltage cascaded control is also introduced for faster set-point tracking. Extensive simualtions were performed in Matlab/Simulink to validate the efficacy of a grid interfaced PV along with BSS to address power void issues.

Balancing the rift between demand and production of energy has become one of the major growing co... more Balancing the rift between demand and production of energy has become one of the major growing concerns globally. This has prompted the technocrats, policy-makers, etc. to contemplate on the potency of renewable energy (RES) sources. The outcome has resulted in the world-wide adoption of RES to meet energy deficits. However various grid codes govern their integration to the grid. These monitor the functioning of the RES power converters and impose active and reactive power injection requirements. This is termed as the low voltage ride-through capability of the power converters in order to ensure unnecessary tripping of the interfacing converter resulting in sudden demand-shift on the conventional sources. Cascaded failures and blackouts could be an immediate result. Furthermore proper, fast and dynamic tracking and synchronization of the grid angle also emerges as a necessity in order to respond to the scenario of sudden grid disconnection. But the vulnerability of the grid-interfac...

IEEE Systems Journal

In this article, we propose a novel, model-independent, unified detection strategy based on disag... more In this article, we propose a novel, model-independent, unified detection strategy based on disagreement Laplacian potential for effective identification of cyber anomalies in interconnected autonomous direct current (dc) microgrid (MG) clusters. This interconnection enables inter and intra-microgrid power exchange between them, thereby rendering efficient and maximum utilisation of the distributed energy resources. However, these clusters are vulnerable to cyber intrusion that disrupt the power sharing schemes. As such, we have investigated the effect of false data injections at various vulnerable points, including both voltage and current sensors in primary, and data transmission points in the distributed secondary, local, and global tertiary layers. Simultaneously, a logical evaluation in the form of data-integrity indices are formulated from the outcomes of the proposed detection scheme to provide for their timely mitigation. Ultimately a fault-ride through operation of the converters is achieved instead of alienating the misbehaving component, unlike previously reported works.

IEEE PEDES 2020, 2020

The uncertainties caused by renewable energy sources (RESs), droop control, etc. often undermine ... more The uncertainties caused by renewable energy sources (RESs), droop control, etc. often undermine the performance of distributed DC microgrids. In this paper, we have investigated the functioning of a novel consensus-based secondary control strategy to achieve proportionate current sharing and voltage synchrony in a generalized networked multiple DC microgrid clusters with hybrid energy storage system (HESS) by compensating mismatches in droop coefficients,line resistances,etc. Alongside, frequency based power sharing and voltage regulation is achieved in a decentralized manner to circumvent load transitions. An optimal, event-based communication strategy has been designed for the sharing of state information with neighboring converters over limited bandwidth. Design procedure, stability analysis, performance under communication adversities are provided to help determine the suitability of the proposed technique. Finally, simulation results for different test-cases are presented to validate the efficacy and robustness of the proposed method.

IEEE PESGM 2020, 2020

In this paper, the authors have attempted to address the problem of power sharing in networked hy... more In this paper, the authors have attempted to address the problem of power sharing in networked hybrid AC/DC micro-grid clusters by utilising back-to-back converter. The hierarchical distributed cooperative control strategy is employed for both the AC and DC microgrid clusters (intra-microgrid control) and an inter-microgrid control strategy employing back-to-back converter for enabling power sharing among the clusters according to the required needs. The distributed secondary control for both the AC and DC MGs aid to reprimand the voltage drops due to presence of cable resistance and droop characteristics. It thus helps to achieve a regulated voltage at both the AC and DC PCC. Particularly in AC MG, it enhances the voltage and power quality. Further, it is worth noting that most of the consensus algorithms are asymptotically convergent and hence in order to achieve finite-time convergence, a modified consensus approach is used for the DC microgrid cluster. This is done to achieve faster consensus irrespective of the unforeseen disturbance / transients that may occur in the AC microgrid clusters. The distributed dynamic averaging consensus algorithm based on PI controllers (DAC-PI) is also investigated for robustness against physical and communication failures. With the proposed inter and intra-microgrid cluster control mechanism, power balance between three phase AC MGs and DC MG is illustrated in this work. This could be utilised as practical applications in stand-alone microgrids, marine power systems, more electric aircraft power systems and can be equipped with mode selection algorithms to enable connection to the utility thereby endowing flexibility and reliability to the network of microgrid clusters. Extensive simulations of test-cases are provided with MATLAB/Simpowersystems platform to elucidate the performance of the proposed control strategy and the hybrid infrastructure.

PESGRE, 2020

The work presented investigates the dynamics of a reverse droop current controller and a conventi... more The work presented investigates the dynamics of a reverse droop current controller and a conventional droop voltage controller in a distributed cooperative secondary control environment operating with the consensus aided communication network for a 5-bus DC microgrid (MG). The microgrid system considered has multiple distributed energy resources (DER) i.e. photovoltaic array and battery connected to 4 buses while the last bus serves as an interconnection for a remote load terminal. This aids in bolstering the performance analysis of the aforementioned controllers under various operating scenarios like switching networks, delay, plug-n-play,etc. The current dynamics being faster than the voltage dynamics, a single current controller could be employed instead of voltage controller or a cascaded voltage-current controller for reducing system complexity and achieving faster convergence. A low voltage DC microgrid test-system (48 V) assuming (semi) dispatchable energy sources at its inputs catering to local and remote resistive & constant power loads is considered in the study to investigate and validate the controllers' transient responses. Index Terms-Muti-agent systems (MAS),hierarchical control, reverse droop, sliding mode control (SMC), constant power load (CPL). I. INTRODUCTION Distributed control employing cooperative networks being the cynosure of research in parallel multi-converter systems continues to intrigue the intellect and presents ample problem statements to be embarked upon. The centre-flocking and collision avoiding features of animals and birds,natural phenomena like thermodynamic laws, insect swarming, flocking of birds, phase transitions etc. in physical, chemical and biological processes, etc. were studied using consensus algorithms and later correlated to multi-agent systems, communication networks[1],[2] which endow mobility to control decisions via exchange of information among agents in accordance with the designed or inherent communication protocols. These laws were then further extended to microgrids (MGs) realizing its strong potential for the correction of the flaws that arise owing to the line impedances superimposing the effect of droop control using virtual impedances for accurate load current sharing in DC and AC parallel multi-converter systems[3]-[6] and to eliminate single-point-of-failure and ameliorate high communication channel bandwidth requirements on account of centralized communication infrastructure.This symbiosis of electrical properties and communication networks commonly known as networked multi-agent systems (MAS) have garnered legit attention owing to their flexibility ,scalability and computational efficiency [7]. It also presents the concept of independent, mobile, distributed agents (controllers) that could take decisions of their own by processing information of their nearest agents (controllers). Tracking and synchronization of these agents are the broad classifications in the distributed control theory [8], wherein it concerns leaderless and leader configurations respectively. It is noteworthy to mention that the sudden inclination towards DC distribution systems reverberated on account of its supremacy over AC supply for not including issues related to power quality, avoiding multiple stages of conversion, enhanced efficiency, higher renewable penetration (DC in nature),etc. The multifaceted benefits

ICPS, 2019

This paper investigates the performance assessment of droop controlled converters in a low inerti... more This paper investigates the performance assessment of droop controlled converters in a low inertia, low voltage DC microgrid scenario. It employs a generalized DC distribution network consisting of both current-controlled and voltage-controlled voltage source converters and a mix of constant impedance, constant current and constant power loads. Since in large distribution networks, lack of inertia is the cause of instability, virtual impedance based methods and capacitor control techniques have been proposed. A RC-based droop control strategy is employed in this work in order to impart inertia to the system thereby improving the transient performance of the network. The converters considered are both grid-feeding and grid-forming in order to analyze the response in the presence of dissimilar electrical energy sources. The grid-feeding converters, both voltage and current-controlled, are interconnected via communication layer and are governed by the consensus laws for multi-agent systems. The networked control systems aids in achieving proper load current sharing and desired voltage regulation. This is essential for the operation of critical loads. The study presents a comparative assessment of the response of RC-droop and conventional droop in the varied microgrid conditions. The cyber-physical system is modeled in MATLAB/Simulink and tested against various operating situations and cyber adversities to test the efficacy of the control law.

Bijni Complex, Laitumkhrah Shillong-793003 Certificate I hereby certify that the work which is be... more Bijni Complex, Laitumkhrah Shillong-793003 Certificate I hereby certify that the work which is being presented in the M.Tech Thesis entitled "FPGA based Digital Control of Grid-connected Distributed Generation Systems", in partial fulfillment of the requirements for the award of the Master of Technology in Electrical Engineering with Power and Energy Systems as specialization and submitted to the Department of Electrical Engineering of National Institute of Technology, Meghalaya is an authentic record of my own work carried out during Autumn Semester 2015 under the supervision of Dr.Gayadhar Panda, Associate Professor.

In this paper, the authors have attempted to address the problem of power sharing in networked hy... more In this paper, the authors have attempted to address the problem of power sharing in networked hybrid AC/DC micro-grid clusters by utilising back-to-back converter. The hierarchical distributed cooperative control strategy is employed for both the AC and DC microgrid clusters (intra-microgrid control) and an inter-microgrid control strategy employing back-to-back converter for enabling power sharing among the clusters according to the required needs. The distributed secondary control for both the AC and DC MGs aid to reprimand the voltage drops due to presence of cable resistance and droop characteristics. It thus helps to achieve a regulated voltage at both the AC and DC PCC. Particularly in AC MG, it enhances the voltage and power quality. Further, it is worth noting that most of the consensus algorithms are asymptotically convergent and hence in order to achieve finite-time convergence, a modified consensus approach is used for the DC microgrid cluster. This is done to achieve faster consensus irrespective of the unforeseen disturbance / transients that may occur in the AC microgrid clusters. The distributed dynamic averaging consensus algorithm based on PI controllers (DAC-PI) is also investigated for robustness against physical and communication failures. With the proposed inter and intra-microgrid cluster control mechanism, power balance between three phase AC MGs and DC MG is illustrated in this work. This could be utilised as practical applications in stand-alone microgrids, marine power systems, more electric aircraft power systems and can be equipped with mode selection algorithms to enable connection to the utility thereby endowing flexibility and reliability to the network of microgrid clusters. Extensive simulations of test-cases are provided with MATLAB/Simpowersystems platform to elucidate the performance of the proposed control strategy and the hybrid infrastructure.

—The report investigates the performance of Direct and Indirect-Model Reference Adaptive Control ... more —The report investigates the performance of Direct and Indirect-Model Reference Adaptive Control schemes for the angular motion control of a helicopter which is achieved by tilting its main rotor and as a result altering the direction of the rotor thrust vector. This action includes a change in the angular moments acting on the vehicle and results in pitch,roll and yaw angular motion. In hover, the helicopter pitch dynamics depend primarily on the vehicle pitch rate q(t) and on the applied longitudinal control input δ(t) which is equivalent in its effect to an elevator of a fixed-wing aircraft. Extensive simulations in MATLAB/Simulink have been implemented investigate the performance of the schemes. I. SYSTEM MODEL The pitch dynamics of an aircraft assuming constant thrust while ignoring the small vertical and forward speed components can be approximated by he equation (1). ˙ q = M q q + M δ δ (1) where, M q =-0.61 rad/s represents the vehicle pitch damping and M δ =-6.65 rad/s 2 is the elevator effectiveness. The objective is for the pitch dynamics to have a desired closed-loop tracking behavior given by the reference model. ˙ q ref = M qr q ref + M δr q cmd (2) II. CONTROL OBJECTIVE To design a direct and indirect MRAC δ(t) such that the plant state q(t) in (1) tracks the reference model given by (2) as a series of step input commands of different magnitudes eg. from t=0-5 s, q cmd = +1 • ;t=5-10 s, q cmd = −1 • ;t=10-15 s, q cmd = +2 • ;t=15-20 s, q cmd = −2 • ;t>20 s, q cmd = +3 •. The reference model has parameters M qr =-4 and M δr =-4. For the purpose of control design, the plant parameters M q is unknown and only the sign of M δ (i.e.negative) is known. For the indirect scheme it is assumed that |M δ | > 2. III. CONTROLLER EXPRESSIONS This section details the mathematical expressions for both the Direct and Indirect Model Reference Adaptive Control schemes in order to provide an insight for the design of the controller. A. Direct Model Reference Adaptive Control (DMRAC) In the direct MRAC , the controller is designed keeping in view the following : (a) the error between the output of plant and reference model is identically zero for identical initial conditions. (b) an initial error will vanish with certain dynamic. Considering the plant model given by (3). ˙ q = M q q + M δ δ (3) where, M q , M δ are unknown and q is measurable. The reference model for the plant can be modeled as ˙ q ref = M qr q ref + M δr δ r (4)

Inroduction DC Microgrids are gaining popularity due to high efficiency, high reliability and eas... more Inroduction DC Microgrids are gaining popularity due to high efficiency, high reliability and ease of interconnection of renewable sources as compared to ac system. In this study the dc-dc power conversion topologies have been analyzed. In order to achieve safe and reliable MG performance, its dynamic stability needs to be ensured in all operating conditions. Averaging and linearization is a common approach for modeling, analysis and design of switching power converters in DC MGs. The resulting small signal models are valid for frequencies of upto around half of the switching frequency because the bandwidth of practical converters are typically in the range of one tenth of the switching frequency.