Research On D-STATCOM Control Strategy Based On AF-SVHP

The static synchronous compensator(D-STATCOM)is applied to the distribution network to effectively improve the power factor and the power quality of the grid.D-STATCOM has multiple functions such as reactive power compensation,harmonic suppression and compensation of three-phase asymmetric current,which has become a research hotspot in the field of power quality control in recent years.This dissertation proposes an ip-iq current detection method without phase-locked loop and an AF-SVHP control strategy,aiming at improving the overall power supply quality of the distribution network and improving the safety and economy of the power grid system.In order to realize the detection and control strategy,the mathematical model of the three-phase three-wire D-STATCOM system is first established,and the dynamic mathematical model is established by the topology diagram of the three-phase three-wire D-STATCOM.In this dissertation,a current-detection method without phase-locked loop is proposed.The reference positive sine and cosine signals are used to calculate the fundamental positive sequence sine and cosine signals.This method can eliminate the error caused by the phase-locked loop circuit and make the detection results basically immune to the grid voltage distortion.Or the effect of asymmetry can improve its detection of the compensation current.In the research of D-STATCOM control strategy,this dissertation proposes a new AF-SVHP control strategy to replace the voltage-current double-closed-loop PI control strategy.This control strategy modulates the PI parameters by using fuzzy control,which effectively improves the control.Accuracy,in addition,it effectively utilizes the zero voltage vector,reduces the high switching frequency caused by the phase-to-phase effect,improves the utilization of the DC-side voltage,and eliminates the delay of current detection by using a method based on linear reference current prediction time effect.Finally,this dissertation builds a three-phase two-level D-STATCOM prototype,which verifies the control strategy proposed in the three-phase balanced and three-phase unbalance,which is feasible and effective in the three-phase two-level D-STATCOM system.Thedissertation has 46 pictures,6 tables,and 55 references.