Capacity optimisation method of distribution static synchronous compensator considering the risk of voltage sag in high-voltage distribution networks

Unlike the traditional methods that only take static voltage stability or minimum network loss into consideration when optimising capacity of distribution static synchronous compensator (D-STATCOM), a new approach is proposed with considering the risk of voltage sag as well as the network loss and the investment cost of D-STATCOM. This approach can balance the investment cost and technical performance. Monte Carlo method is used for the random setting of fault types and locations to obtain the original probability of voltage sag under some given configuration schemes. Moreover, through revealing the hidden relationship between the original probability and the real-time load, the converted probability is presented to fit the expression for calculating the original probability of voltage sag with respect to the size of additional D-STATCOM. Finally, a single-objective capacity optimisation model is established to obtain the optimum size of additional D-STATCOM, which is based on the economic assessment method of risk. The proposed method is validated in Chinese Dongguang Distribution Networks. The result confirms this method can not only reduce the loss of voltage sag, but also significantly improve the efficiency of D-STATCOM.