考虑频变特性的直流线路故障行波精确计算方法及应用

输电线路参数存在频变特性,若在直流输电线路故障行波暂态计算中将其等效为固定不变的常数,则必然会导致计算误差增大。为此,文中基于叠加原理提出了适用于任意波形的时序波阻抗矩阵,以描述行波电压和电流间时域的频变关系;此外,利用双指数波对行波波形进行拟合,以获取更高的计算精度。在此基础上,将所提出的方法应用于直流线路故障测距,提出了一种考虑直流线路频变特性的故障定位新方法。基于PSCAD/EMTDC的实际直流工程算例的大量仿真测试表明,所提行波暂态计算方法能有效计及直流线路参数频变特性,对暂态行波的计算更精确,进一步提高了故障测距精度。

Accurate Traveling Wave Calculation Method for HVDC Transmission Lines Fault Considering Frequency Characteristic and Its Application

Constant transmission line parameters are bound to lead to a greater traveling wave calculation error due to the frequency dependent characteristic of transmission line. So, based on the superposition theorem, a time sequence wave impedance matrix is given in this paper. The matrix describes the non-linear relationship between traveling wave voltage and current in time domain for any waveform. In addition, the double exponential wave is used in fit-ting transient waveform to obtain higher accuracy. On this basis, the proposed method is applied to fault location, and a fault location algorithm for high-voltage direct current(HVDC)transmission lines considering frequency characteristic is proposed. A lot of simulation results based on PSCAD/EMTDC platform are given to demonstrate that the traveling wave calculation method can effectively consider the frequency dependent characteristic of transmission line, has higher accuracy and lays a foundation for engineering application such as further improvement of the calculation of the fault location algorithm etc. This work is supported by National Natural Science Foundation of China(No.51577072)and Fundamental Research Funds for the Central Universities(No. 2013ZZ028).