基于电流相角分布的光伏直流送出线保护方案

Photovoltaic Direct Current Transmission Line Protection Scheme Based on Current Phase Angle Distribution

光伏直流送出线发生双极故障时会导致输电线路两端换流器快速闭锁,为保障系统稳定运行,保护装置需在换流器闭锁前快速准确识别故障。为此,提出一种基于两端电流极性变化的相角分布光伏直流送出线保护方案。该方案利用相角值描述故障前后一个数据窗线路两端暂态电流极性的异同,并以此分类构造保护判据,可以准确快速地判断出光伏直流送出线区内外故障。最后,在MATLAB/Simulink中搭建1 MW/±30 kV集中型光伏直流升压外送系统模型进行仿真验证。结果表明,该方案能够快速可靠识别光伏直流送出线上的故障类型,且具有较好的抗干扰和抗过渡电阻能力。

When a bipolar fault occurs on the photovoltaic direct current(DC)transmission line,the converters at both ends of the transmission line will be quickly blocked.To ensure the stable operation of the system,the protection device needs to quickly and accurately identify the fault before the converter is blocked.Therefore,a protection scheme for photovoltaic DC transmission lines based on the phase angle distribution of the current polarity changes at both ends was proposed.In this scheme,the phase angle value was used to describe the similarities and differences of the transient current polarity at both ends of a data window line before and after the fault,and the protection criterion was constructed based on this classification,which can accurately and quickly judge the faults inside and outside the photovoltaic DC output line area.Finally,a 1 MW/±30 kV centralized photovoltaic DC boost output system model was built in MATLAB/Simulink for simulation verification.The results show that the scheme can quickly and reliably identify the fault type of the photovoltaic DC transmission line,and has good anti-interference and anti-transition resistance capabilities.