Grid-Forming Control Scheme of Converter with Functions of the SVG and APF

To solve the abnormal voltage, harmonic resonance, poor active support capability issues of the grid-connected large-scale wind farms, by taking full advantages of the flexibility and controllability of power electronic converters, a grid-forming control method of the converter with functions of the static var generator (SVG) and active power filter (APF) is proposed. By comparing the charging and discharging characteristics of the DC bus capacitor with the acceleration and deceleration characteristics of the synchronous generator, the active power control loop is designed to realize the grid phase tracking, which avoids the use of the phase locked loop (PLL) and reduces the resonant risk. Based on the reactive power-voltage droop control principle, the reactive power control loop is designed to realize reactive power compensation and voltage support. By harmonic current detection and inner-loop current control, the load harmonic current compensation is realized. Finally, the multiple functions of the proposed control method are verified by Matlab/Simulink. The simulation results show that the paralleled SVG+APF integrated grid-forming converter can greatly improve the grid harmonics and power factor, thus enhance the power quality of the power system.