Analysis on Voltage Stability in the Receiver Power Area with High Proportion after the Splitting of Power Grid

For the receiver power system, it is generally acknowledged that after the splitting of power grid the frequency of the islanded grid will decline because of the active power vacancy. But the actual operating experience indicates that when the active power vacancy exceeds certain extent, the voltage will drop but the frequency won't drop and even increases. This article discusses the interaction mechanism of voltage and frequency in the receiver power area at high proportion after the splitting of power grid. Through the simulation of typical example, the impacts of dynamic reactive power support, load characteristic, fault type which leads to splitting, etc. on dynamic process of island frequency are analyzed and it is pointed out that the intensity of system rack, the load characteristic and fault type intensively impact on both island voltage condition and dynamic variation of island frequency. The essence of voltage instability is whether there is a balance point and the voltage sags can affect the dynamic change of frequency. Conclusion of this research is available for reference to safety control of island frequency and voltage after the splitting of power grid.