A Fast Method to Determine Short-circuit Capacity Based on Compensation Impact Factor

This paper proposes a fast method to determine short-circuit capacity for an AC system, which includes a compensation capacitor, to avoid sub-synchronous resonance (SSR) risk at a system planning stage. Firstly, the compensation impact factor (CIF) is calculated for generators with different short-circuit capacities. If CIF of all generators are below the threshold value, then the short-circuit capacity is the safety one. Finally, safety short-circuit capacity group is formed and strongly suggested to the system planning due to no SSR risk threating the system. The proposed method needs simple system modeling and calculation process and little information on generator shaft. Simulation results show that the proposed method can precisely determine the safety short-circuit capacity group for the system. Keywords—sub-synchronous resonance; short-circuit capacity; compensation impact factor