The increasing integration of distributed energy resources such as photovoltaic (PV) systems into distribution networks introduces intermittent and variable power, leading to high voltage fluctuations. High PV integration can also result in increased terminal voltage of the network during periods of high PV generation and low load consumption. These problems can be solved by optimal utilization of the reactive power capability of a smart inverter. However, solving the optimization problem using a detailed mathematical model of the distribution network may be time-consuming. Due to this, the optimization process may not be fast enough to incorporate this rapid fluctuation when implemented in real-time optimization. To address these issues, this paper proposes a co-simulation-based optimization approach for optimal reactive power control in smart inverters. By utilizing co-simulation, the need for detailed mathematical modeling of the power flow equation of the distribution network in the optimization model is eliminated, thereby enabling faster optimization. This paper compares three optimization algorithms (improved harmony search, simplicial homology global optimization, and differential evolution) using models developed in OpenDSS and DigSilent PowerFactory. The results demonstrate the suitability of the proposed co-simulation-based optimization for obtaining optimal setpoints for reactive power control, minimizing total power loss in distribution networks with high PV integration. This research paper contributes to efficient and practical solutions for modeling optimal control problems in future distribution networks.

The paper presents study of an isolated hybrid power system using a proportional integral (PI) controller with a static synchronous compensator (STATCOM) for reactive power control to maintain constant voltage at the generator terminals. The renewable energy sources such as solar, wind, bio-mass, etc. that are intermittent in nature use induction generator as electro-mechanical device for conversion of mechanical to electrical energy, but reactive power is required for the operation of the induction generator in addition to the reactive power required by the load. The synchronous generator used in hybrid system for generating power through diesel system is supplying reactive power to the system partially; therefore, another source of reactive power is required to fulfill this demand. The paper also shows the dynamic performance of the hybrid system both for constant and variable slip conditions and 1% step change in reactive power load by considering wind–diesel hybrid power system as an example.

The growing installation of distributed energy resources (DERs) in a distribution network (DN) poses substantial issues related to voltage regulation. Due to constrained switching operation and slower response time, traditional voltage regulation devices cannot handle current voltage-related challenges. One alternative to solve these problems is to use smart converters to control the reactive power to regulate the voltage. Volt-Var control (VVC) is one of the simplest approaches for controlling the reactive power from smart converters. Among several converters, grid forming converters (GFCs) are more suitable in DER-enriched distribution networks. Since DER-enriched distribution networks have a higher fluctuation in voltage profile, real-time control is advantageous. Therefore, this work presents an advanced real-time reactive power control for handling voltage violations in a DN using GFC. The uniqueness of this method is that it controls the voltage magnitude of affected nodes by dispatching reactive power from smart converters in real-time. By running cyber-physical co-simulation (CPCS) between the Typhoon HIL 604 and OpenDSS, the Volt-Var control can be done in real time. The grid-forming converter is modelled in Typhoon HIL 604, which acts as a physical layer of the proposed cyber-physical system for real-time VVC. A CIGRE medium voltage distribution network is designed in OpenDSS and serves as one of the parts of the cyber layer. The CPCS between Typhoon HIL and OpenDSS and the control algorithm are both done by a programme written in Python. The execution of the control algorithm is performed in real time using the Supervisory Control and Data Acquisition (SCADA) developed in this study. The real-time simulation shows that the proposed real-time VVC is capable of handling voltage violations in real time in DER-enriched distribution networks.

This paper investigates the artificial bee colony (ABC)- and gray wolf optimization (GWO)-based robust controllers in an isolated winddiesel hybrid power system (IWDHPS). The IWDHPS comprises a wind energy conversion system (WECS) and a diesel engine set. A permanent-magnet induction generator and a synchronous generator are used for power generation with WECS and diesel engine set, respectively. The voltage fluctuations at the generator terminal occur because of the mismatch between generated and consumed reactive power in the system, which further causes a reduction in the quality and stability of the power supply. An automatic voltage regulator (AVR) and a static synchronous compensator (STATCOM) are utilized to suppress these voltage fluctuations in the considered system. Both AVR and STATCOM are equipped with proportional integral (PI) controllers with a single input. The performance and robustness conditions of the control system are expressed as the optimization problem based on the H loop shaping. The ABC and GWO algorithms are applied to solve the optimization problem and to achieve the values of PI controllers for AVR and STATCOM simultaneously. The proposed controller performance is compared with the performance of the bacterial foraging optimization algorithm, particle swarm optimization algorithm, genetic algorithm, and conventional based controller, for the same IWDHPS.