Voltage sag frequency kernel density estimation method considering protection characteristics and fault distribution

摘要

The fault distribution has a great influence on the stochastic assessment of voltage sag frequency. Due to bad weather, tree branches and animal contact, it is difficult to predict the position of short-circuit fault, so the position of fault is uncertain. The fault position also has a great influence on the duration of voltage sag when the transmission line adopts distance protection. This paper studies the non-simultaneous trips of protections on two sides of the line and the protection failure when short-circuit fault occurs. Furthermore, this paper presents a new method for stochastic assessment of voltage sag frequency based on kernel density estimation (KDE) and fault position method. Kernel density estimation method can use the historical fault position information to assess the fault distribution more accurately. The new method is applied to IEEE RTS-30, and the results show that the new method is more accurate, objective and practical compared with the traditional methods.