特高压直流分层接入方式下抑制连续换相失败的直流电流控制策略OA北大核心CSTPCD

Due to the coupling of the ultra-high voltage direct current(UHVDC)hierarchical connection system,continuous commutation failure at an inverter can easily lead to cascading faults in the power grid.This article analyzes the difference in control response of high-end and low-end inverters and their dynamic reactive power characteristics based on the inter-layer interaction mechanism.Analysis shows that an increase in reactive power exchange during the fault recovery will lead to a voltage drop of the non-fault layer,and directly causes a decrease in the extinction angle,leading to continuous commutation failure of the non-fault layer.Based on this,a current control strategy is proposed to suppress continuous commutation failure.The strategy suppresses continuous commutation failure by calculating the current command in real-time through reactive power exchange and voltage fluctuation characteristics.An electromagnetic transient model is established,and the strategy's effectiveness is verified by comparing multiple operating conditions.The proposed strategy can reduce the probability of continuous commutation failure while improving the voltage recovery characteristics of the hierarchical connection system,which is conducive to the safe and stable operation of the system.