The Influence of Solar Power Plants on the Vietnam's Power System Transient Stability

The article examines the effect the share of solar photovoltaic power plants (SPP) in the mix of generating capacities of the Vietnam power system has on its transient stability. A characterization of the Vietnam electric power system is given. The power system mathematical model for studying its transient stability with taking into account solar power plants has been constructed. The SPP model takes into account the constraints imposed on the operation of the inverter electronic switches at a reduced voltage at the plant connection node when a disturbance is applied in the system. The limit short circuit clearing time is considered as the transient stability condition. It has been determined that a small share of SPP can slightly improve the transient stability conditions; i.e., the limit short-circuit clearing time increases. With the SPP share of about 40%, the transient stability conditions become slightly degraded: the limit short-circuit clearing time decreases. A further increase in the SPP share above 50% results in that the computation carried out by the software package fails to converge. In the studied range of the SPP share, the degradation of transient stability conditions is not critical, and the existing relay protection and circuit breakers isolate the short circuit place without disrupting the power system transient stability.