The Voltage Stability And Controlling Method Of Power Sysytem Considering Load Characters

Voltage stability is also load stability, power system voltage instability or voltage collapse is an important factor in power system instability. Because voltage collapse accident can cause great economic loss and great influence on the society, it becomes an emergent problem to be solved for the security of power system. With the continuous enlargement of the scale of power systems, the rapid growth of voltage sensitive loads, the expanding increase of burden in load center, the persistent accentuation of the entire power load, as well as the relative insufficiency of reactive power and voltage control methods, voltage instability and voltage collapse occur more and more regularly. Voltage instability and voltage collapse will become more dangerous to the security of power system, and load character research is the key.This paper discusses several topics related to load character and voltage stability: voltage stability mechanism, load modeling, static voltage stability analysis of power systems, voltage stability dynamical analysis method. Combined with load modeling research work of actual power system, the entire process of load modeling and some problems in actual load modeling work are demonstrated and discussed in this thesis. And based on such an issue a dynamic method is put forward to modify the exponents of static load. Based on the interpolation principle, the exponents of static load at the point of steady-state operation are liberalized and dynamically amended with a serial interpolation method.And then a method base on Thevenin's Equivalent is put forward according to continuation power flow (CPF) calculation, to draw the Power versus Voltage curves. This method is applied in IEEE14, with a satisfying outcome.At the same time, based on the results of the research, this paper discusses the stability of voltage considering the load characters and the manners to improve the voltage stability and controlling methods. The methods which could improve the reactive power are also described, such as SVC and STATCOM.Moreover, the methods of power system voltage stability dynamical analysis are also discussed in this thesis. This scheme is adopted on the modular system to evaluate the reactive-load compensation scheme.Furthermore, dynamic voltage stability methods are briefly described here. The process of dynamic load modeling is demonstrated. The load character is evaluated with the application of the research production on the modular system. The merits and drawbacks of various load models are analyzed, as well as the application scenarios.Finally, future work and expectancy fruits are pointed out according to the understanding of the research problems and a summary of this paper.