阀控系统双套切换导致阀组闭锁的原因分析及对策

Cause Analysis and Countermeasure of Converters Locking Caused by Double Converter Control Systems Switching

锁相环是柔性直流输电工程控制保护系统的重要组成部分,其为控制程序提供电网的相位信息,锁相环的输出错误将导致系统的控制保护功能无法正常实现。该文通过分析在昆柳龙多端直流工程现场调试中出现的一起故障案例,发现阀组控制系统双套切换过程中,现有的控制策略无法预防备用系统锁相环输出错误,进而引发故障。针对这一问题,提出依据采样电压波形的频率信息增加备用系统锁相环计算功能闭锁判据的方案,并进行仿真试验,结果验证了该方案的有效性。

Phase-locked loop(PLL)is an important part of the control and protection system of VSC-HVDC project,which provides the control system with the phase information of the power grid.An incorrect output of the phased-lock loop leads to the failure of the system control function.Based on the study of a case which occurred in the commissioning of Kunliulong Multiterminal DC Project,this paper finds that the existing control strategy is not able to prevent the output error of the PLL in the standby system when switching double converter control systems,thus causes the fault.To solve this problem,this paper proposes a scheme to increase the PLL locking criterion based on the sampling voltage waveform frequency in the standby system,and the simulation results verify the effectiveness of the scheme.