The Study Of Power System Voltage Stability Based On Continuation Power Flow

With the reform of electricity market, market participants require to increase the transmission capacity and stability limits of power system, which makes operational conditions of power system become more nervous, so voltage stability problem is prone to come out easily. since continuation power flow is proposed, it has been widely used in the static voltage stability studies of power system, and it will become an important module in the energy management system. In this paper, the core is the algorithm of continuation power flow, Deep and meticulous researches are made for the application of continuation power flow in the voltage stability of power system, and the result given is preferable.Firstly, this paper summaries four components of continuation power flow:predictor,corrector,parametric and step control, and the way of load growth is summarized. A new parameterization technique for the continuation power flow is proposed in this paper. This method with the principle of geometric similarity is simple, understandable, and continuation power flow improved by linear-nonlinear predictor and adaptive variable step size can trace the limit of the power with good convergence. The desired results obtained with the proposed method applied to the IEEE39 bus and IEEE118 test systems demonstrate the correctness and validity.Secondly, the mechanism of limit induced bifurcation is summarized, two bifurcation phenomena:QV constraint exchange and limit induced bifurcation are introduced in this paper, corresponding to the stable state and unstable state of the power system respectively. A method for searching voltage stability point is used base on reactive power limit guided continuation power flow, then using the symbols changes of Jacobian matrix eigenvalues to identify voltage stability point. The good results are obtained with the method applied to the IEEE4 bus and IEEE39 bus test systems, which shows limit induced bifurcation in power system is a very common. Because of the phenomenon of limit induced bifurcation, which maks voltage stability analysis results of the power system base on saddle node bifurcation may be prone to the optimism.Finally, the static and dynamic load model is summarized, the trend ofλV curve and PV curve about different load models and the comparison of voltage stability are analyzed from the view of mathematical through a single load infinite bus system, obtained the nose ofλV curve corresponds to the nose of PV curve only in the constant power load model, the nose ofλV curve corresponds to the second half of support of PV curve in the non-constant power load model, and the constant power load most likely to lose stability while the constant impedance load does not exist the problem of instability. The effect of maximum load factors,critical voltage and its load power are analyzed by different proportion of load in ZIP load model in the IEEE30 bus system, obtained that the static limit of load is increased, and voltage stability of the system is improved using ZIP load model relative to using the constant power load.