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The proposal focuses on the role of data centres (DCs) and electric vehicle (EV) energy storage systems (ESSs) for frequency regulation and it provides a new opportunity for different resources to participate in the power sector. Frequency fluctuations are introduced with the emergence of inverter‐dominated renewable energy sources (RESs) as it does not provide rotational inertia to the grid, such as synchronous generators. In this study, the virtual synchronous generator (VSG) controlled inverter compensates for the lack of inertia. Particularly, this research work analyses the involvement of DC and EV batteries as ESSs in designing an integrated technical virtual power plant (VPP) to support frequency variations using the VSG concept. Microgrid (MG) simulations are performed in MATLAB/ Simulink platform. Case studies are carried out to validate the grid export and grid import performance of the model by using variations in the load and the solar irradiance of the MG. It is verified that bidirectional power flow takes place between the proposed VPP components and the grid that enables the grid with high penetration of RESs. The work provides a conceptual framework for future contributions towards the smarter usage of assets such as ESS and a greener future. [ABSTRACT FROM AUTHOR]

The proposal focuses on the role of data centres (DCs) and electric vehicle (EV) energy storage systems (ESSs) for frequency regulation and it provides a new opportunity for different resources to participate in the power sector. Frequency fluctuations are introduced with the emergence of inverter-dominated renewable energy sources (RESs) as it does not provide rotational inertia to the grid, such as synchronous generators. In this study, the virtual synchronous generator (VSG) controlled inverter compensates for the lack of inertia. Particularly, this research work analyses the involvement of DC and EV batteries as ESSs in designing an integrated technical virtual power plant (VPP) to support frequency variations using the VSG concept. Microgrid (MG) simulations are performed in MATLAB/ Simulink platform. Case studies are carried out to validate the grid export and grid import performance of the model by using variations in the load and the solar irradiance of the MG. It is verified that bidirectional power flow takes place between the proposed VPP components and the grid that enables the grid with high penetration of RESs. The work provides a conceptual framework for future contributions towards the smarter usage of assets such as ESS and a greener future. [ABSTRACT FROM AUTHOR]

A fully distributed hierarchical control strategy for multiple inverters‐based AC microgrid is proposed. The developed controller provides real‐time economic dispatch along with the network frequency and average voltage restoration. The controllers cooperate with neighbours using sparse communication network and perform local computations to achieve the assigned objectives. The economic dispatch control unit is embedded with the frequency restoration at the secondary level controller to change the active power supply from the inverter. The voltage controller along with reactive power controller ensures the proportional reactive power sharing as well as network average voltage regulation. The average voltage regulation aids the individual inverter to provide required reactive power demand, with a small, comprise at the terminal output voltages from the nominal values. The convergence of the proposed controller is proved using the Lyapunov stability criteria. The maximum allowable communication delay that obligate stable microgrid operation is derived. The simulation results verify the efficacy of the proposed controller. Experimental validation is also presented, and the controller ability to ride through communication failure and load perturbation condition is demonstrated. [ABSTRACT FROM AUTHOR]

For low-voltage autonomous microgrids, the essential goal is maintaining stable voltage and frequency throughout its network for the smooth operation of distributed loads. The other goal is to maintain proportionate power-sharing between multiple sources connected through voltage source converters (VSCs). For the particular case of a heavily loaded microgrid, any further increase in demand poses new problems. The VSCs proximate to the loads may overshoot beyond its maximum ratings. Owing to which the stability of the power supply, as well as the longevity of VSCs, may get compromised. Also, these sources provide power under varying composite loading conditions comprising both linear and non-linear loads resulting in unbalancing in its network. To overcome these problems, a decentralised fast terminal sliding mode control strategy for active power-sharing between parallel VSCs has been proposed. A detailed mathematical model based on Lyapunov's stability theorybased study is designed to establish the operating stability of the proposed controller. To validate the proposed control strategy, MATLAB-based simulation results are provided for possible loading scenarios. A comparative study for performance evaluation between the proposed controller and a conventional proportional -integral-based controller is further carried out. Finally, the performance of the proposed controller is also validated in real-time scenario. [ABSTRACT FROM AUTHOR]

For low‐voltage autonomous microgrids, the essential goal is maintaining stable voltage and frequency throughout its network for the smooth operation of distributed loads. The other goal is to maintain proportionate power‐sharing between multiple sources connected through voltage source converters (VSCs). For the particular case of a heavily loaded microgrid, any further increase in demand poses new problems. The VSCs proximate to the loads may overshoot beyond its maximum ratings. Owing to which the stability of the power supply, as well as the longevity of VSCs, may get compromised. Also, these sources provide power under varying composite loading conditions comprising both linear and non‐linear loads resulting in unbalancing in its network. To overcome these problems, a decentralised fast terminal sliding mode control strategy for active power‐sharing between parallel VSCs has been proposed. A detailed mathematical model based on Lyapunov's stability theory‐based study is designed to establish the operating stability of the proposed controller. To validate the proposed control strategy, MATLAB‐based simulation results are provided for possible loading scenarios. A comparative study for performance evaluation between the proposed controller and a conventional proportional ‐integral‐based controller is further carried out. Finally, the performance of the proposed controller is also validated in real‐time scenario. [ABSTRACT FROM AUTHOR]

This study proposes a modified decentralised droop controller for inverter‐based autonomous photovoltaics (PV) microgrids to address the problem of instability and slower power sharing between PV inverters. The proposed controller modifies the conventional droop mechanism in transient as well as in steady state by adding an auxiliary control signal in the power control loop of the inverters. The proposed approach offers three key benefits, i.e. improves active power sharing, enhances system stability and performs the secondary control action by nullifying the frequency deviation by using only one auxiliary signal in the control loop. The accuracy of the proposed modified droop controller is verified with the help of time‐domain simulations in MATLAB/SIMULINK. The results obtained show that the controller is able to improve the power sharing and stability of the microgrid as well as to restore frequency. The performance of the proposed control scheme is also validated by experimental results and small‐signal analysis. [ABSTRACT FROM AUTHOR]

This study presents an optimal control operation of a photovoltaic-battery based standalone microgrid, feeding nonlinear loads. To ensure continuous power supply to the critical loads during low insolation or low battery state of charge, a diesel generator (DG) is used as an auxiliary generator. This cost effective hybrid system with maximum utilisation of the renewable as well as fossil fuel based generators can be employed in hospitals, telecom stations in remote areas. In order to nullify the effect of non-linear loads on the DG, modified enhanced phase-locked loop (EPLL) based power quality conditioner is used. The characteristic equation of conventional EPLL is amplitude dependent, thus, the controller tuning parameters need to be modified if the input signal varies over a large range. The presented controller overcomes this problem making the system more robust in eliminating noise and harmonics and extracting fundamental component of a given signal. This component is drawn from the DG with the help of a voltage source converter, thus, making its current always distortion free. The proposed control scheme is simulated in MATLAB. Furthermore, experimental verification is done on a laboratory prototype of the same. The steady state and dynamic responses of the system validate its satisfactory performance. [ABSTRACT FROM AUTHOR]

This study presents an optimal control operation of a photovoltaic‐battery based standalone microgrid, feeding non‐linear loads. To ensure continuous power supply to the critical loads during low insolation or low battery state of charge, a diesel generator (DG) is used as an auxiliary generator. This cost effective hybrid system with maximum utilisation of the renewable as well as fossil fuel based generators can be employed in hospitals, telecom stations in remote areas. In order to nullify the effect of non‐linear loads on the DG, modified enhanced phase‐locked loop (EPLL) based power quality conditioner is used. The characteristic equation of conventional EPLL is amplitude dependent, thus, the controller tuning parameters need to be modified if the input signal varies over a large range. The presented controller overcomes this problem making the system more robust in eliminating noise and harmonics and extracting fundamental component of a given signal. This component is drawn from the DG with the help of a voltage source converter, thus, making its current always distortion free. The proposed control scheme is simulated in MATLAB. Furthermore, experimental verification is done on a laboratory prototype of the same. The steady state and dynamic responses of the system validate its satisfactory performance. [ABSTRACT FROM AUTHOR]

This study proposes a novel wind turbine generator (WTG) imbalance fault classifier using gene expression programming (GEP). Proposed GEP fault classifier is able to achieve very high classification accuracy with relatively small number of samples. Ours is a first attempt at designing a WTG imbalance fault identifier using GEP for fault segregation. The identifier does not assume prior knowledge of WTG model. Raw current data of permanent magnet synchronous generator stator side are processed through empirical mode decomposition to generate 16 intrinsic mode functions or IMFs. Classifier employs the J48 algorithm to further prune these 16 IMFs to eight most relevant input variables which serve as inputs to the GEP imbalance fault classifier. The authors compare performance of the proposed GEP classifier with other contemporary artificial intelligence (AI) based classifiers such as neural networks and support vector machines[AQ ID=Q2]. Simulation results and performance comparison against other AI approaches elucidate that the proposed GEP‐based identifier could serve as an important tool for WTG fault diagnosis. [ABSTRACT FROM AUTHOR]

This study presents a novel handshaking approach to reduce transformer and line overloading using plug-in electric vehicles (PEVs) connected to a photovoltaic (PV) assisted charging station (CS) via vehicle-to-grid (V2G) control strategy. The discharging behaviour of PEVs on receiving an aggregator command is carried out using a priority index function under two variant of customer command: (i) normal charging; and (ii) fast charging. Moreover, it is carried out to maximise aggregator profit in an optimal fashion by broadcasting to each CS and scheduling their dispatch based on the available power feedback from each CS. The energy command compliance for handshaking is ensured in a sturdy manner using a (N - 1) contingency approach considering the uncertain mobile behaviour of PEVs. Owing to the highly unlikely travelling behaviour of PEVs, a novel distributed consensus-based power restoration between a fleet of CSs is proposed to endure handshaking using average power contribution from the rest of the CS if (N - 1) contingency fails for any CS. The proposed strategy has been tested on a 1 kVA FPGA-based experimental setup to validate the proposed control scheme under different scenarios. [ABSTRACT FROM AUTHOR]

This study presents a novel handshaking approach to reduce transformer and line overloading using plug‐in electric vehicles (PEVs) connected to a photovoltaic (PV) assisted charging station (CS) via vehicle‐to‐grid (V2G) control strategy. The discharging behaviour of PEVs on receiving an aggregator command is carried out using a priority index function under two variant of customer command: (i) normal charging; and (ii) fast charging. Moreover, it is carried out to maximise aggregator profit in an optimal fashion by broadcasting to each CS and scheduling their dispatch based on the available power feedback from each CS. The energy command compliance for handshaking is ensured in a sturdy manner using a (N−1) contingency approach considering the uncertain mobile behaviour of PEVs. Owing to the highly unlikely travelling behaviour of PEVs, a novel distributed consensus‐based power restoration between a fleet of CSs is proposed to endure handshaking using average power contribution from the rest of the CS if (N−1) contingency fails for any CS. The proposed strategy has been tested on a 1 kVA FPGA‐based experimental setup to validate the proposed control scheme under different scenarios. [ABSTRACT FROM AUTHOR]

In this study, an artificial neural network (ANN) and empirical mode decomposition (EMD) based condition monitoring approach of a wind turbine using Simulink, FAST (fatigue, aerodynamics, structures and turbulence) and TurbSim is presented. The complete dynamics of a permanent magnet synchronous generator (PMSG) based wind turbine [i.e. wind turbine generator (WTG)] model is simulated in an amalgamated domain of Simulink, FAST and TurbSim under six distinct conditions, i.e. aerodynamic asymmetry, rotor‐furl imbalance, tail‐furl imbalance, blade imbalance, nacelle‐yaw imbalance and normal operating scenarios. The simulation results in time domain of the PMSG output stator current are decomposed into the intrinsic mode functions using EMD method then RapidMiner‐based principal component analysis method is used to select most relevant input variables. An ANN model is then proposed to differentiate the normal operating scenarios from five fault conditions. The analysed results proclaim the effectiveness of the proposed approach to identify the different imbalance faults in WTG. The presented work renders initial results that are helpful for online condition monitoring and health assessment of WTG. [ABSTRACT FROM AUTHOR]

Unity power factor injection from single‐phase photovoltaics (PVs) located towards the end of a residential feeder leads to voltage rise problems. Also, unbalanced current injection due to variable solar insolation results in voltage unbalancing and makes the situation worst. A decoupled controller for a single‐phase PV inverter is proposed to improve the voltage profile of the distribution feeders. The proposed controller consists of the following components: voltage regulator (to control the amount of reactive power injection), outer voltage control loop (slow controller to set the reference for the inner current loop), inner current control loop (to control the PV inverters) and modified second‐order generalised integrator (to generate fundamental frequency). A sample distribution systems consisting of several PVs located in all three phases and a three‐phase induction motor load is considered. The real‐time hardware‐in‐the‐loop simulations are performed to test the efficacy of the proposed controller scheme. Results show the improvement in voltage regulation of different buses. [ABSTRACT FROM AUTHOR]

A control strategy is formulated for photovoltaic generators (PVG) operating in parallel in a Microgrid. A radial microgrid is considered and when it is isolated from the utility grid, the PVG's must operate in the voltage-frequency control mode in the absence of a storage or a diesel generator unit. It is observed that the conventional P-f and Q-v droop control method fails to deliver correct power references for inverters operating in parallel when network impedance is unequal, and therefore an active power-reactive power-frequency-derivative (PQFD) droop control is proposed to achieve an error free power sharing. Seamless operation from the grid connected mode to isolated mode and vice-versa is achieved with the help of the aforementioned control, which in addition assists in the alleviation of sluggish response in the presence of Induction motor (IM) loads by providing appropriate damping. For a transient free transfer from isolated mode to grid connected mode, a synchronisation control is formulated which helps in the proper reconnection. The controller designed is tested in both Microgrid and the grid connected mode and during transition. The controller gains used in the paper have been obtained with the help of a small signal analysis of the system considered. [ABSTRACT FROM AUTHOR]

All the sources are required to supply the scheduled power to the system as directed by the system operator, within a time frame of operation. The fluctuating nature of wind makes supplying the scheduled power a challenging task. To address this, gas turbines are proposed to augment the wind generator to work as buffer owing to their high ramping capability. However, the cost of gas turbine increases with increased ramp rates, whereas, operating efficiency and the life time decreases. Hence, to relieve the buffering gas turbines from higher ramp rate requirements, emulation of inertia of the wind generator is proposed in this paper. The controller is designed to operate in inertia emulation mode whenever there is a retardation of rotor of the wind turbine and the proposed ramp controller will be in action only for first few seconds after the fall in wind speed. While emulating the inertia, the performance of the proposed control philosophy with different ramp rates is investigated in this paper. Guide lines for the selection of the ramp duration and ramp rate for seamless transition from inertia emulation mode to maximum power extraction mode are also suggested in this paper. [ABSTRACT FROM AUTHOR]

This study proposes a grid supportive control scheme for a single‐phase photo‐voltaic (PV)‐based inverter to mimic the behaviour of a synchronous generator during grid voltage/frequency variations. The converter embedded with the proposed controller, termed as a 'single‐phase synchronverter', transforms a large segment of rooftop PV, which is, in general, single phase, to an ancillary service provider in compliance with the grid code (i.e. if the grid code allows rooftop PV to provide inertial/primary frequency/voltage response). Owing to fluctuations in incident solar irradiation, a battery has been connected at the dc link to take care of the variability in PV output power. The challenges involved in extending the three‐phase synchronverter philosophy to a single‐phase converter have been discussed and the performance of the resultant single‐phase synchronverter to different values of virtual inertia and droop/regulation has been analysed. An experimental setup is developed and the system behaviour for different operating conditions has also been studied. [ABSTRACT FROM AUTHOR]

All the sources are required to supply the scheduled power to the system as directed by the system operator, within a time frame of operation. The fluctuating nature of wind makes supplying the scheduled power a challenging task. To address this, gas turbines are proposed to augment the wind generator to work as buffer owing to their high ramping capability. However, the cost of gas turbine increases with increased ramp rates, whereas, operating efficiency and the life time decreases. Hence, to relieve the buffering gas turbines from higher ramp rate requirements, emulation of inertia of the wind generator is proposed in this paper. The controller is designed to operate in inertia emulation mode whenever there is a retardation of rotor of the wind turbine and the proposed ramp controller will be in action only for first few seconds after the fall in wind speed. While emulating the inertia, the performance of the proposed control philosophy with different ramp rates is investigated in this paper. Guide lines for the selection of the ramp duration and ramp rate for seamless transition from inertia emulation mode to maximum power extraction mode are also suggested in this paper. [ABSTRACT FROM AUTHOR]

A control strategy is formulated for photovoltaic generators (PVG) operating in parallel in a Microgrid. A radial microgrid is considered and when it is isolated from the utility grid, the PVG's must operate in the voltage‐frequency control mode in the absence of a storage or a diesel generator unit. It is observed that the conventional P‐f and Q‐v droop control method fails to deliver correct power references for inverters operating in parallel when network impedance is unequal, and therefore an active power‐reactive power‐frequency‐derivative (PQFD) droop control is proposed to achieve an error free power sharing. Seamless operation from the grid connected mode to isolated mode and vice‐versa is achieved with the help of the aforementioned control, which in addition assists in the alleviation of sluggish response in the presence of Induction motor (IM) loads by providing appropriate damping. For a transient free transfer from isolated mode to grid connected mode, a synchronisation control is formulated which helps in the proper reconnection. The controller designed is tested in both Microgrid and the grid connected mode and during transition. The controller gains used in the paper have been obtained with the help of a small signal analysis of the system considered. [ABSTRACT FROM AUTHOR]

Sluggish tracking for change in solar irradiations is the main demerit of the perturb and observe (P&O) algorithm because of its fixed perturb. To overcome this, an adaptive tracking algorithm based on Takagi-Sugeno fuzzy implications is proposed in this study. Input to the fuzzy controller is the error between conductance and incremental conductance which is otherwise zero at the maximum power point. The P&O algorithm and the proposed algorithm along with the recently published adaptive incremental conductance algorithm are examined for their performance efficacy on a photovoltaic (PV) generating system with fabricated as well as real irradiation data. As a case study, all the considered algorithms are validated under partial shading conditions also. The effectiveness of the proposed algorithm is verified for the tracking of the maximum power point of a PV system in steady as well as changing irradiations and the conclusions are supported through some experimental validations. [ABSTRACT FROM AUTHOR]

Sluggish tracking for change in solar irradiations is the main demerit of the perturb and observe (P&O) algorithm because of its fixed perturb. To overcome this, an adaptive tracking algorithm based on Takagi–Sugeno fuzzy implications is proposed in this study. Input to the fuzzy controller is the error between conductance and incremental conductance which is otherwise zero at the maximum power point. The P&O algorithm and the proposed algorithm along with the recently published adaptive incremental conductance algorithm are examined for their performance efficacy on a photovoltaic (PV) generating system with fabricated as well as real irradiation data. As a case study, all the considered algorithms are validated under partial shading conditions also. The effectiveness of the proposed algorithm is verified for the tracking of the maximum power point of a PV system in steady as well as changing irradiations and the conclusions are supported through some experimental validations. [ABSTRACT FROM AUTHOR]