Shah Fahad

Conventionally, a virtual synchronous generator (VSG) is designed for islanded mode (IM) operation to meet specific operational requirements such as the rate of change of frequency (RoCoF). However, the operation of VSG designed for IM may not meet the operational and control criteria in grid connected mode (GCM) when the grid conditions vary. In addition, conventional VSG control technology does not consider the influence of the presynchronization scheme when connected to a weak grid, which degrades the RoCoF in IM. To overcome the aforementioned challenges, the proposed study presents a twin-delayed deep deterministic policy gradient (TD3) algorithm to improve the seamless transition performance of VSG from IM to GCM and vice versa. In the first step, the VSG-based power system model is used as a foundation for problem formulation of the proposed TD3 algorithm. Secondly, a reward function is designed according to the performance requirements, i.e., frequency and RoCoF requirements, of the VSG in order to guide the training of the agent in varying load, power reference, and grid conditions. Finally, the superiority of the proposed algorithm over existing methods is validated in MATLAB/SIMULINK and RTDS based real-time simulation environment.

Over the past decade, PQ regulation schemes for a single-controllable active distribution network (ADN) using coordination among a network of virtual synchronous generators (VSGs) have been proposed. However, considering the variable nature of intermittent renewable energy sources (IRESs), coupling a cluster of IRESs with the point of common coupling (PCC) of ADN could inflict transient issues for the power management of the whole ADN. To counter these challenges, the proposed study has three main objectives: 1) To propose a modified mathematical model that represents the apparent resistance-reactance at the PCC of ADN in relation to the PQ coordination among the network of VSGs; 2) to utilize the proposed model for deriving a $\mu$ synthesis-based robust controller that overcomes the uncertainty in the moment of inertia response of all the VSGs; 3) and to present the stability and performance analysis of the proposed controller validated under model uncertainty. Validation of the proposed method and its comparison to the state-of-the-art methods in MATLAB/Simulink environment confirms that the proposed method significantly minimizes the impact of disturbances on the power management of the whole ADN.

This article presents a data-driven approach that adaptively tunes the parameters of a virtual synchronous generator to achieve optimal frequency response against disturbances. In the proposed approach, the control variables, namely, the virtual moment of inertia and damping factor, are transformed into actions of a reinforcement learning agent. Different from the state-of-the-art methods, the proposed study introduces the settling time parameter as one of the observations in addition to the frequency and rate of change of frequency (RoCoF). In the reward function, preset indices are considered to simultaneously ensure bounded frequency deviation, low RoCoF, fast response, and quick settling time. To maximize the reward, this study employs the Twin-Delayed Deep Deterministic Policy Gradient (TD3) algorithm. TD3 has an exceptional capacity for learning optimal policies and is free of overestimation bias, which may lead to suboptimal policies. Finally, numerical validation in MATLAB/Simulink and real-time simulation using RTDS confirm the superiority of the proposed method over other adaptive tuning methods.

Investigation of power output from PV arrays under different fault conditions is an essential task to enhance performance of a photovoltaic system under all operating conditions. Significant reduction in power output can occur during various PV faults such as module disconnection, bypass diode failure, bridge fault, and short circuit fault under non-uniform shading conditions. These PV faults may cause several peaks in the characteristics curve of PV arrays, which can lead to failure of the MPPT control strategy. In fact, impact of a fault can differ depending on the type of PV array, and it can make the control of the system more complex. Therefore, consideration of suitable PV arrays with an effective control design is necessary for maximum power output from a PV system. For this purpose, the proposed study presents a comparative study of two intelligent control schemes, i.e., fuzzy logic (FL) and particle swarm optimization (PSO), with a conventional control scheme known as perturb and observe (P&O) for power extraction from a PV system. The comparative analysis is based on the performance of the control strategies under several faults and the types of PV modules, i.e., monocrystalline and thin-film PV arrays. In this study, numerical analysis for complex fault scenarios like multiple faults under partial shading have also been performed. Different from the previous literature, this study will reveal the performance of FL-, PSO-, and P&O-based MPPT strategies to track maximum peak power during multiple severe fault conditions while considering the accuracy and fast-tracking efficiencies of the control techniques. A thorough analysis along with in-depth quantitative data are presented, confirming the superiority of intelligent control techniques under multiple faults and different PV types.

Smart grid integrates computer, communication, and sensing technologies into existing power grid networks to achieve significant informatization-related advantages. It will provide communication between neighbors, localized management, bidirectional power transfer, and effective demand response. Smart grids (SG) replace conventional grids by integrating various operational measures, including smart automation appliances, smart meters, and renewable energy sources. Regarding energy management and resolving energy issues, SG is one of the most cutting-edge and potentially game-changing innovations. Even still, its complexity suggests that decentralization may provide significant gains. Because of its increasing digitization and interconnectedness, it is also vulnerable to cyber threats. Blockchain, in this sense, is a potential SG paradigm solution that provides several great benefits. Even though blockchains have been widely discussed to decentralize and strengthen smart grid cybersecurity, they have not yet been researched in depth from an application and architectural standpoint. Blockchain-enabled SG applications are the subject of an in-depth research investigation. Electric vehicles (EVs), home automation, energy management systems, etc., are only a few of the many examples that have prompted the proposal of blockchain designs for their respective use cases. Information communication network security is of paramount importance. However, this evolving system raises cybersecurity issues. This paper aims to guide researchers in the right manner so they may build blockchain-based, secure, distributed SG applications in the future. This article also summarizes cybersecurity threats pertaining to smart grids. It starts with a description of a blockchain followed by the blockchain infrastructure, challenges, and solutions for different smart grid applications. A look back at the tried-and-true methods of securing a power grid is offered, and then it discusses the newer and more complex cybersecurity threats to the smart grid. In addition, models of common cyberattacks are presented, and the methods of defense against them are examined.

Swift population growth and rising demand for energy in the 21st century have resulted in considerable efforts to make the electrical grid more intelligent and responsive to accommodate consumers’ needs better while enhancing the reliability and efficiency of modern power systems. Internet of Things (IoT) has appeared as one of the enabling technologies for smart energy grids by delivering abundant cutting-edge solutions in various domains, including critical infrastructures. As IoT-enabled devices continue to flourish, one of the major challenges is security issues, since IoT devices are connected through the Internet, thus making the smart grids vulnerable to a diverse range of cyberattacks. Given the possible cascading consequences of shutting down a power system, a cyberattack on a smart grid would have disastrous implications for the stability of all grid-connected infrastructures. Most of the gadgets in our homes, workplaces, hospitals, and on trains require electricity to run. Therefore, the entire grid is subject to cyberattacks when a single device is hacked. Such attacks on power supplies may bring entire cities to a standstill, resulting in massive economic losses. As a result, security is an important element to address before the large-scale deployment of IoT-based devices in energy systems. In this report, first, we review the architecture and infrastructure of IoT-enabled smart grids; then, we focus on major challenges and security issues regarding their implementation. Lastly, as the main outcome of this study, we highlight the advanced solutions and technologies that can help IoT-enabled smart grids be more resilient and secure in overcoming existing cyber and physical attacks. In this regard, in the future, the broad implementation of cutting-edge secure and data transmission systems based on blockchain techniques is necessary to safeguard the entire electrical grid against cyber-physical adversaries.

Virtual synchronous generator (VSG) control has received much attention for interfacing renewable energy sources, thus creating a low-inertia microgrid. However, proportional reactive power-sharing and voltage accuracy is still a serious concern due to unequal feeder impedances between VSG controlled DGs and the point of power coupling. This article proposes a virtual variable impedance (VVI) based VSG control technique to mitigate the reactive power sharing error by improving the line-impedance ratio among multiple DGs. The proposed VVI control is designed to estimate the value of variable virtual impedance by establishing an exponential relationship with the inverter's output reactive power. The reactive power communication method is also introduced to identify the proportion of reactive power share being injected by the DG. The effectiveness of the proposed VVI control is further analyzed through the small-signal stability analysis and Lyapunov stability analysis of a multi-VSG system. Finally, the proposed controller is tested in MATLAB/Simulink software and on an experimental setup that includes inverter hardware and dSPACE simulator. Results have shown that the proposed method allow only 0.026% of reactive power sharing error as compared to the conventional droop control and state-of-the-art virtual capacitor-based droop control that experiences 2.86% and 2.8% error, respectively.

Virtual synchronous generators (VSGs) deployed into an islanded microgrid emulates the Q-V droop nature of a synchronous generator. Although the Q-V droop control of VSGs enhances the voltage stability, the installed distant VSGs have unequal line impedances due to their random location and rated capacity. The unequal line impedance hinders the proportional reactive power-sharing between VSGs. The proposed study is focused on minimizing the reactive power sharing error by introducing a virtual parallel inductor (VPI) concept. A mathematical model is proposed to create and exploit the analogous relation between the exponential behavior of the VPI and the controllable voltage source to mitigate the reactive power sharing error and simultaneously strengthen the voltage control accuracy. In addition, a droop within a droop strategy is introduced to enhance the reactive power sharing capability of the VSGs. Furthermore, a detailed eigenvalue analysis is conducted to evaluate the limitations of the proposed model. Finally, to test the superiority of the proposed model over the state-of-the-art methods, simulation and hardware experimental results are presented.

The explosive demand for electricity and ecological concerns has necessitated the operation of power networks in a more cost‐effective approach. In recent years, the integration of combined heat and power units has presented a potential answer to these problems; nevertheless, a new difficult challenge has emerged: finding an optimal solution for simultaneous dispatch of power and heat. Therefore, to tackle this problem, this work presents an intelligent sequential algorithm based on a hybridization of an enthusiasm‐aided teaching and learning‐based optimization algorithm (ETLBO) with an improved version of particle swarm optimization (IPSO). The proposed method can simultaneously minimize total generating costs while considering a variety of physical and operational limitations. In addition, this research designed an adaptive violation constraint management approach combined with the formulated hybridized optimization algorithm to ensure system constraints' safe preservation during the optimization process. Finally, the performance of the proposed method is compared to the recently developed metaheuristic algorithms as well as Knitro and IPOPT (industrially used optimization packages), in which the ETLBO‐IPSO outperforms all the other methods.