Security And Economy Comprehensive Evaluation Research Of City High Voltage Power Grid

City high voltage power grid is an important part of power system, and it not only concerns the safe operation of the higher level grid but also affects people’s daily lives. To ensure the safe operation of power system, the operation staff must know well the operation state, so the security levels classification has extremely important significance on the power grid. Along with the development of the competitive power market, power grid companies pay more attention to the economy operation of the grid for the pursuit of a higher economic efficiency. So now the analysis of the power grid needs consider the safety and economy comprehensively. To this end, this paper does much researches on the security and economic evaluation of the grid. The main work is as follows:First, the extended conic quadratic programming is proposed to calculate the total supply capacity which meets the N-1 contingency analysis. On this basis, the paper defines the loss rate index, the danger index, the system extra capacity, load entropy, and the comprehensive safety index. The indicators can qualitatively and quantitatively describe the grid severity degree of the fault and the safety degree after fault.Secondly, a new security levels classification system is established. On the basis of the static security analysis, the paper distinguishes the safe normal state and the unsafe normal state. Considering the severity degree after fault and the capacity of the grid withstanding the load fluctuation, the grid security levels is divided into five levels according to the above index values. The security levels classification system can comprehensively character the grid security, and it can reflect the system security qualitatively and quantitatively. At the same time, the load boundary vector is calculated to master the limit operation condition at each load point and to find out the weak load point of the power grid.Finally, a set of economy evaluation index system of city high voltage power grid is established. Then the paper sets up the multiple classification model to evaluate the economy based on the support vector machine. Considering the contradiction between the security and economy, this paper calculates the economic value of the security based on the value function. And it can provide effective supplement for the economic evaluation.