Rapid Calculation Of Static Voltage Stability On The Power Systems After A Contingency

In power market, 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 has enhanced the calculating speed so greatly that the power system is able to meet the needs of online computing. At last, verify the reliability and the practicability of the method with the C + + programming language. Specific work mainly concentrated in the following four aspects:(1) This paper first introduced the voltage stability of the basic concepts.the significance and the phenomenon of voltage stability, the classification voltage stability and voltage stability study's history and status quo, the main methods of static voltage stability analysis are the main contents of this paper. A simple system model of a static analysis of voltage stability has been found.By studying the static voltage stability of a simple system, the paper clear some basic concepts of static voltage stability .Finally get some basic conclusions about voltage stability though a simple system.(2)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. And put the explanations on the problems (such as the choice of the continuous parameter,sensitivity, identify the critical point, the complementary application of the conventional and the continuous power flow, the different varying ways of load) which is probably occurred in the calculation with continuous power flow.(3)Two new algorithm is used to get the power system voltage stability margin after the contingency: SNB point of tracking curve method,using this method 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. In addition, the prediction and calibration equation which is used to get the SNB point after the contingency can be solved with special matrix reducing techniques.By using this techniques can simplify the procedures designed and reduce the memory occupation; SNB points higher-order Taylor approximation method, the formula presented in this method to calculate the high-order sensitivity has good expression. Solution procedure of State variables and load margin for the high-order sensitivity are based on the same coefficient matrix, repeated factor table decomposing is not needed.Eigenvector of high-order derivative is not needed in this method. Calculation speed and high accuracy is the outstanding feature of this method.(4)Two methods have been used to calculate the result in the corresponding power systems, and the result proved the correctness of these two methods, and the advantages compared with the traditional method.