基于参数识别原理的VSC-HVDC输电线路单端故障定位

One-Terminal Fault Location for VSC-HVDC Transmission Lines Based on Principles of Parameter Identification

为保障电压源换流器型直流输电(voltage sourceconverter HVDC,VSC-HVDC)系统的可靠运行,提出一种基于参数识别原理的VSC-HVDC输电线路单端故障定位方法。由于VSC-HVDC输电线路两端并联大电容,识别故障距离的时候,在0模分量网络中可以把两端的换流站系统等效为电容,通过参数识别的原理列写出包含故障距离和过渡电阻2个未知参数的故障定位时域微分方程,通过最小二乘法优化求解该方程即可得到故障距离和过渡电阻,从而实现故障定位。PSCAD下的仿真结果表明,该方法能够实现VSC-HVDC输电线路的准确故障定位,最大测距误差不超过1%。该方法仅需要单端电气量就能实现准确故障定位,对采样频率的要求不高,理论上不受过渡电阻的影响,可以满足VSC-HVDC输电线路故障测距的要求。

To ensure reliable operation of voltage source converter HVDC （VSC-HVDC） transmission system, a one-terminal fault location method for VSC-HVDC transmission line is proposed. Because high-capacity capacitors are connected to both ends of VSC-HVDC transmission line, so during the fault location the converter station systems at both ends of VSC-HVDC transmission line can be equivalent to capacitors in the network of zero-mode component, and by means of the principle of parameter identification the differential equations in time-domain, which contains two unknown parameters of fault distance and transition resistance, can be listed, and solving this equation by least square optimization both fault distance and transition resistance can be attained, thus the fault location is implemented. The proposed method only needs single end electric quantities and is undemanding to sampling frequency, besides, theoretically this method is not affected by transition resistance, so it can meet the demand on fault location for VSC-HVDC transmission lines. Results of PSCAD simulation show that the proposed method can implement accurate fault location for VSC-HVDC transmission line while the maximum location error is not more than 1%.