Study On VSG Stability Control And Primary Frequency Regulation Of Renewable Energy Sources

In order to reduce carbon emissions,reduce air pollution and reliance on fossil fuels,it has become the consensus of developed countries and regions to vigorously develop renewable energy sources(RES).However,when renewable energy is connected to the grid for power generation,it is designed to run at the maximum power point.The RES does not possess the same inertia and damping capacity as of the traditional generators.Therefore,grids with a high proportion of renewable energy sources are more susceptible to external disturbances;at the same time,as the proportion of renewable energy connected to the grid increases,they continue to occupy the share of traditional synchronous generators.Therefore,the reserve capacity of the system is correspondingly reduced,hence reducing the system's ability to respond to instabilities and failures,leading to a sharp increase in the safety and stability of the power system.Inverter control based on virtual synchronous generator(VSG)technology can simulate the inertia of synchronous generators in the power grid and the external characteristics of primary frequency regulation,thereby improving the grid-connected performance of renewable energy power generation and enhancing the frequency stability of the power grid.This research work conducted a systematic research on the VSG control method,taking photovoltaic power generation as an example,the primary frequency modulation and power stability of the multi-voltage source inverter photovoltaic system based on the master-slave droop control method under high penetrability are analyzed.Case studies of PV-VSG system are studied under the influence of different irradiance and temperature,etc.The innovative results obtained are:1.Propose a single VSG grid-connected control parameter optimization method based on particle swarm optimization(PSO)algorithm to obtain the optimal droop coefficient Dp,inertia coefficient J,and damping coefficient D of the VSG grid-connected control.The simulation analyzes the influence of different irradiance and temperature on the control performance of a single grid connected VSG grid,and verifies that the control coefficient optimized based on the improved particle swarm optimization(PSO)algorithm has better control performance and effect than the control coefficient determined by the traditional method.2.A control parameter optimization method based on an improved genetic algorithm(GA)is proposed,and the optimal damping coefficient D,droop coefficient Dp and moment of inertia J under each working condition are obtained,in addition to the Kp and Ki coefficients of the PI controller.Furthermore,the frequency regulation of the distributed microgrid composed of multiple photovoltaic VSGs and its performance results during the change in load demand are studied.The simulations of two different case studies with respect to load change,the results show that the reactive and active power of each VSG is quickly stabilized,and the control parameters optimized by the improved genetic algorithm show better results in reducing the stability time and overshoot of the system than the control parameters determined by the classical method.3.Based on the IEEE 14-Bus system,the distributed battery storage integrated VSG power generation system(PV-BSS)at three random locations to complete the system modeling and simulation research.Furthermore,the proposed system is verified by the application of the improved genetic algorithm based on the determination of the optimal solution.The damping coefficient D,the droop coefficient Dp and the moment of inertia J and the Kp and Ki coefficients of the PI controller have minimum overshoot and fast stability in the system frequency and active power regulation.