Rapid Risk Assessment of SSR Caused by Series Capacitors Compensations in Large Power Grid

For large scale AC/DC transmission schemes with multiple series capacitors compensations, how to assess the risk of subsynchronous resonance (SSR) rapidly is of great practical significance to ensure that the grid operates safely and stably. According to the practical project of meeting summer peaks in 2009 of China Southern Power Grid (CSG), this paper combines a static equivalence method, Modified Two Point Loadflow Calculation which takes resistance into account with frequency scanning method and realizes the rapid risk assessment of SSR caused by multiple series capacitors compensations in large scale power grid. Then by using PSCAD/EMTDC, the detailed electromagnetic transient model (of course including the shaft model) is established to do the fault simulation certification aiming at generating units which have the risk of SSR. The simulation results show that Mohong and Yanchong series capacitors may lead to transient torque amplification of steam turbines Xiaolongtan and Xunjiansi while the other series capacitors have a much lower possibility of initiation of SSR.