基于参数识别的长线距离保护研究

In this paper, the algorithm of line inserting is introduced to deduce the formula calculating the voltage and current along the line in time domain So that the problem of getting the voltage and current along the line in any point is solved when line model adopts distribute parameter in a low sampling frequency. The action reliability of distance protection is higher than before. The fault distance is calculated by differential equation using the terminal voltage and current of the distance protection based on R-L line model in the time domain. It has a low request for sampling frequency and is not affected by distribution capacitance current and non-periodic component, responses quickly. Results of simulation show that the scheme can distinguish in area faults or out area faults rightly and avoid the transient overreach effectively, improving the performance of distance protection, when the fault occurs at the terminal of EHV long-line transmission.