Evaluation for Maximum Allowable Capacity of Renewable Energy Source Considering AC System Strength Measures

Abstract

In this paper, a method to calculate the maximum allowable capacity (MAC) of renewable energy sources (RESs) in terms of AC system strength is presented; the equivalent short-circuit ratio (ESCR) and the newly proposed reactive power considered equivalent short-circuit ratio (QESCR) are considered. Unlike conventional measures, the reactive power afforded by RESs is considered when calculating the QESCR; the MAC of RESs increases because their reactive power outputs stabilize transmission networks. Based on the AC strength measures, an optimization problem to evaluate the MAC of RESs and determine their optimal locations is developed. The optimization problem is formulated in mixed-integer linear programming (MILP). To validate the effectiveness of the proposed method, it is applied to two test systems: the IEEE RTS-79 test system and a real-world Korean transmission network. The proposed method allows facile calculation of the MAC of RESs, which ensures that the transmission network remains stable.