A comparative study on voltage stability bifurcation control ability of SVC and STATCOM

In this paper, the bifurcation analyses were made in a single-machine PQ dynamic-load system and a classical 3-node system. It is verified that both SVC and STATCOM compensation could effectively delay the occurrence of saddle-node bifurcation(SNB) in the two systems, and as greater as gains of the compensation devices are, the better the control effect to SNB point is; and STATCOM always plays better than SVC when concerned with the same value of their gains. In the 3-node system that can appears the Hopf bifurcations, SVC and STATCOM can effectively delay the unstable Hopf bifurcation(UHB). When the gain values of SVC and STATCOM are the same and both of them are small, the control effect of SVC and STATCOM to UHB is almost the same; while both of the gain values are great, the control effect of STATCOM to UHB is apparently superior that of SVC. It can be demonstrated that the bifurcation control ability of STATCOM for voltage stability is more superior than that of SVC with a comprehensive consideration.