Rapid Sensitivity Calculation Of Voltage Stability On The Power System Under N-1 Topology

Under power market environment, in order to make the power system working more efficiently, electric network is often running close to the limit of state. In order to keep electric network running safely and stably, steady-state voltage stability of the electric network computing margin, and security and stability of the electric network after the accident occurred on is very important. This paper presents the method that can quickly calculate the static voltage stability margin after a branch outage contingency of the electric network. This method greatly increased computing speed,so that is able to meet the needs of power system online computing. At last, verify the reliability and the practicability of the method with the C programming language.At first, this paper introduced the basic concepts of the voltage stability, and then introduce the power system network calculation method in detail.Found a model to calculate the bifurcate point of the voltage stablility on electric power systems. Especially introduced the algorithm to get the bifurcate point of the voltage stablility with the continuous power flow method. Based on critical point information obtained by continuous power flow solution under base network topology,the SNB point curve tracking method was been proposed.Used this method,we can get the feasible solution under the serious contingency of power system which can not get by using the conventional methods. The solution can be used in contingency evaluation and contingency defending. Finally, introduced the SNB points higher-order Taylor approximation method.Branch admittance was been taken as a parameter in this method, the exact solution about the critical point of the system which has a branch outage contingency can be obtained quickly by using Taylor's series expansion and calculating 1 to N degree derivatives of the original system. The coefficient matrices of different derivatives of the system state variables and the load margin are not changed with the derivative n; therefore, it is no necessary for repeated factorization by using the proposed method to obtain the derivatives with different orders and the calculation burdens are much smaller than other methods.These two technique was been tested on IEEE bus system in this paper.The result proved the correctness of these two methods, and the advantages compared with the traditional method.