基于复合移相控制的直流输电系统换相失败响应优化研究

摘要

At present, the main control strategies for the domestic HVDC projects are ABB strategy and SIEMENS strategy.This paper analyzes the difference of these two strategies on dealing with commutation failure.It is pointed out that commutation failure with SIEMENS strategy lasts longer than that with ABB strategy, for the reason that SIEMENS strategy still relies on PI (proportional and integral) regulation during inverter AC fault period and its response speed is quite slow compared to the decreasing rate of extinction angle;whereas this regulation has its advantages that it improves the accuracy of extinction angle in steady operation.Then a compound phase-shifting control is proposed based on the SIEMENS strategy, including the phase-shifting control strategy considering the rising rate of DC current as wells as the phase-shifting control strategy considering both unbalance and magnitude of AC voltage.Finally, we present the detailed parameters of the proposed controller.The simulation results show that the application of the compound phase-shifting control contributes to preventing commutation failure or shortening its duration, as well as improving power recovery and system response during fault period, compared with original control strategy.%目前国内直流输电工程采用的控制策略主要有基于ABB技术路线的控制策略和基于SIEMENS技术路线的控制策略.该文对两类控制策略针对换相失败的应对方式进行了分析对比,指出基于SIEMENS路线的策略虽然有利于提高稳态运行时关断角的控制精度,但相对于基于ABB路线的控制策略换相失败持续时间更长,主要原因为逆变侧交流故障下前者仍采用比例积分控制器(proportional and integral ,PI)对触发角进行调节,响应速度较慢.基于上述分析,对基于SIEMENS路线的控制策略提出了附加复合移相控制策略,具体包括基于直流电流上升率检测的移相控制策略和基于交流电压不平衡度与幅值检测的移相控制策略,并给出控制器的详细设计参数.仿真结果显示,相对于原始控制策略,投入复合移相控制策略有助于预防换相失败或缩短换相失败时间,加速功率恢复,提升直流系统故障下响应特性.