Research On Parameter Adaptation Adjustment Method Of VSC-HVDC Receiving-side Converter Station For Supplying Power To Passive Network

Voltage Source Converter based High Voltage Direct Current(VSC-HVDC)has the advantages of no commutation failure risk,fast power flow reversal,independent control of active and reactive power,and is suitable for connecting various distributed power sources.It is widely used in clean energy grid connection,urban power supply,long-distance transmission,DC distribution network and passive network power supply.When VSC-HVDC supplies power to the passive network,due to the large output reactance of the inverter side,the voltage quality problems of voltage sag and voltage swell are prone to occur in the receiving-end system when the load is switched.Therefore,it is of great engineering significance to study the voltage quality and stability of VSC-HVDC power supply to passive networks.This paper takes the double-ended VSC-HVDC supplying power to the passive network as the research object,and divides the system into two parts:the rectifier side(sending side)and the inverter side(receiving side).The rectifier station adopts the outer loop constant DC voltage and constant power control mode to provide reference values for the inner loop current control,and the inverter station adopts the feedforward decoupling constant AC voltage and constant frequency control mode to meet the AC load demand.Then,according to the main circuit structure and control strategy of the VSC-HVDC system supplying power to the passive network,the DC side small-signal impedance modeling is carried out,and the impedance mathematical model of the entire system is obtained.After the impedance model is verified,the stability and stability margin of the system are analyzed.Then,the quality of the power supply voltage of the passive network is studied and analyzed,and the mathematical relationship between the parameters and the voltage drop in the transient process is obtained.According to the relationship between the filter capacitor and the voltage sag,the suppression effect of the filter capacitor on the voltage sag and the quantitative calculation method of the voltage sag peak are studied.Finally,according to the relationship between the time constant and the voltage drop in the mathematical relationship,the adaptive function of parameter adj ustment is mainly designed,and the correlation coefficient of the adaptive function is set according to the stability margin and dynamic response requirements.Matlab/Simulink simulation software is used to build a double-ended VSC-HVDC system that supplies power to the passive network,and the designed parameter adaptive function is added to the control link for simulation research.The simulation results show that,compared with the traditional fixed parameters,the adaptive function can suppress the AC voltage sag depth when the load suddenly increases,and can reduce the AC voltage rise amplitude when the load suddenly decreases.It can be seen that the parameter adaptive adjustment method can improve the power supply voltage quality of the passive network while taking into account the stability,and provide high-quality power for the AC load on the passive network side.