Static Voltage Stability Planning Of Distribution Network With Wind Power Access

Static voltage stability analysis can reflect the volage stability level of power system to some extent. With the increasing access of distributed generation,especially wind generation,its impact on voltage stability is bigger and bigger.Therefore,how to locate the wind power generation and optimize reactive power configuration to improve static voltage stability level with wind power access is a problem worthy of further study.Conventional optimal reactive power dispatch approaches operate mostly using certain methods.When random factors are ignored,certain methods can analyze reactive power dispatch problems accurately.With the access of large amount of new energy generation, traditional certain methods are faced with challeges. New energy generation access makes power injections unfixed. How to improve the voltage stability and reduce the risk of voltage callapse is a pro blem to be solved.In addition,because of the randomness and volatility of new energy generation,the traditional index measure of voltage stability has not fully adapted to this situation.As a result, new index is needed to measure the node variable impact on instability case.The index should be able to deal with the voltage stability critical point of saddle node bifurcation and limit induced bifurcation.In this paper, we obtain the following achievements:(1) To settle down the drawback of traditional participation factor based allocation method,in this paper, a normal vector index based on voltage stability limit surface is proposed to measure the node variable impact on voltage stability with wind generation access into power system. Numerical simulation of IEEE 33 system demonstrates the validity of the proposedmethod. Compared to the traditional index, normal vector index has a wider range of application because it can deal with the voltage stability critical point of saddle node bifurcation and limit induced bifurcation.(2) On the basis of the normal vector of voltage stability limit surface mentioned before, a reactive power allocation method of distributed network is conducted. Numerical results in IEEE 33 demonstrate that this method is able to improve voltage stability and decrease the risk of operation.Numerical examples suggest that, normal vector is able to choose the vulnerable point. Adopting of this method will decrease the risk of operation and increase the margin of system operation。(3) Against the randomness of wind generaton output,this paper develops a voltage stability margin constrained stochastic optimal reactive power dispatch(VC-SORPD) method. The chance-constrained programming is solved through genetic algorithm and stochastic power flow based on point estimation. Simulation results on several cases demonstrate that the proposed method is able to prevent under and over-compensation and increase load margin at a cost of a small but acceptable increase of active power losses.Some techniques are adopted to improve the computational speed. Numerical examples validate the feasibility of those techniques.