Transient Voltage Stability Analysis For South China Electric Power Grid

With increasing scale of grid interconnection and augment of transmission line power transfer capability, voltage collapse accidents have been reported many times and concerned by researchers in the whole world.. According to the construction of South China Electric Power Grid (SCEPG) in 2005, this paper analyses transient voltage stability in large-scale power system and obtains many helpful conclusions.First, simulating software TSAT is introduced in detail, including main functions and performance assessments. Subsequently, on the background of SCEPG in 2005, simulation data pretreatment tasks include: topology analysis, appropriate static equivalence for the specific system, physical modeling for dynamic element. Research work is focused on summer-peak load operation mode in this paper. On the base of the operation mode, transient angle stability and transient voltage stability are analyzed in detail respectively. And transient power transfer capability of SCEPG is fully expounded. Investigated contingencies include HVDC monopole block, HVDC bipolar block, three-phase permanent fault in each of 500kV single ac transmission lines and some 500kV double ac transmission lines, generator disconnecting and load shedding. Based on the different generation proportion of YunNan and GuiZhou, there are three kinds of power transfer modes, in which transient power transfer capability from the west to the east is researched. Using the same contingency and the different load model, angle stability in sending side and voltage stability in receiving side become two central problems. Some measures that can improve transient power transfer capability of SCEPG are adopted. Focusing on transient voltage stability in receiving side, induction motor load model become the emphasis in this paper. Investigating work includes characters of motor mechanical load, proportion of motor in total load, character of motor low-voltage protection, optimal location of compensation equipment and topology of power grid. All of these contribute to transient voltage stability. To improve the character of transient voltage, many measures of var compensation have been concerned. They are switching shunt capacitor banks, fixed shunt capacitor in generator bus, SVC and synchronous condenser. At last, many important conclusions on how to improve transient voltage stability have been made.