Research On Resonance Suppression Methods Based On APF And TSC Hybrid Compensation System

Harmonics and reactive power are two important indicators of power quality in power systems.Due to the large number of applications of power electronic equipment,harmonic problems and reactive power problems have become increasingly serious,resulting in increased power grid power loss and frequent equipment failure accidents.Safe and stable operation brings serious harm.Therefore,a hybrid compensation system TAPF composed of an active power filter(APF)capable of quickly and continuously compensating for harmonic reactive power and a thyristor switching capacitor(TSC)with large reactive power compensation capacity and low cost is used in power quality management Widely used.But TAPF system also has problems such as resonance,which affects the effect of harmonic compensation and system stability.This article takes the TAPF system as the research object,analyzes the resonance problems existing in the process of the TAPF system in the treatment of harmonic reactive power,and the impact of resonance on the system stability.Limitations,and then based on this,improved methods are proposed to ensure the stability of the system.The specific work is as follows:First,the mathematical model of the TAPF system is established,the principle of resonance in the closed-loop control of harmonic current is analyzed,and the harmonic currents of the grid are plotted against the resonant frequency and the proportional gain coefficient of the current controller respectively.Load harmonic current and power grid harmonic voltage amplitude-frequency characteristic response diagram,and Harmonic current controller open-loop transfer function Bode diagram,thereby analyzing the impact of these two factors on harmonic compensation capacity and system stability.Then,the resonance suppression method based on PCC point voltage proportional feedback is studied,and the physical principle of resonance suppression can be analyzed.Based on the TAPF system analysis,the resonance damping range based on PCC point voltage proportional feedback is small.And because of the coexistence of virtual reactance and the fluctuation of the grid impedance itself,the system still has resonance problems.Then,in view of the above problems,this paper proposes a PCC point voltage feedback control method that can perform resonance damping in the entire frequency band(that is,within the system sampling frequency range),increasing the resonance damping range and improving system stability.Finally,a TAPF experimental platform is set up,and its hardware selection,key parameter design,control circuit design,key control algorithm and software design are discussed,and the effectiveness of the proposed resonance suppression method is verified by experiments.