Probabilistic estimation of PCC loss due to voltage sags in large power systems

In this paper probabilistic estimation of PCC loss is approached in distribution systems. For the difficulty of directly solving the impedances of the star-connected equivalent model, a port-based model is adopted for voltage magnitude calculation under four fault types (TPF, SLGF, LLF and DLGF). The specific energy (SE) function is used to evaluate voltage sags involving the voltage magnitude and sag duration simultaneously, and PCC loss is directly computed from the trip probability density, which derives from the normal probability distribution function of SE. The distribution characteristic of balanced and unbalanced faults is also considered. The estimation method for PCC loss is proved fast and effective by IEEE RBTS system.