换相失败期间送端系统暂态有功建模及其支撑策略研究

Transient active power modeling of a sending system and its support strategy during commutation failure

针对逆变侧交流故障导致换相失败期间送端系统所遭受的有功冲击问题,首先,基于换相失败期间直流等值电路明确了换相失败后整流器有功波动的主导因素,并计及换相失败期间直流电压的波动特性分析了整流侧各电气量与控制量的响应机理,从而确定了整流侧各直流电气量与控制量暂态响应与送端系统传输有功极值时刻之间的关系。其次,基于换相失败期间的拉氏运算电路,推导建立了换相失败后送端系统各电气量的时域表达式,实现了整流器的暂态有功建模。通过划分时间区间对低压限流环节进行优化改进,利用直流电流时域表达式补偿直流电流指令值,提出了基于传输有功暂态极值时刻的有功支撑策略。最后,PSCAD与CIGRE-HVDC的仿真结果验证了理论分析的正确性与有功支撑策略的有效性。

There is an active impact of the sending system during a commutation failure caused by an AC fault on the inverter side.Based on the DC equivalent circuit during the commutation failure,the dominant factor of the active power fluctuation of the rectifier after the commutation failure is clarified.The response mechanism of each electrical quantity and control quantity on the rectifier side is analyzed by considering the fluctuation characteristics of the DC voltage during the commutation failure.This is to determine the relationship between the transient response of each DC electrical quantity and the control quantity on the rectifier side and the transmission active extreme value moment of the sending system.Then,based on the tensile operation circuit during the commutation failure,the time-domain expressions of each electrical quantity of the sending end system after the commutation failure are deduced and established.The transient active power modeling of the rectifier is realized.By dividing the time interval to optimize and improve the low-voltage current limiting link,the DC voltage time-domain expression is used to compensate for the DC current command value,an active support strategy based on the transmission active power transient extreme moment is proposed.Finally,the simulation results of PSCAD and CIGRE-HVDC verify the correctness of the theoretical analysis and the effectiveness of the active support strategy.