Research Of Security Forewarning Classification For Power System Based On Risk Assessment

With the increase of power system interconnection scale and the improvement of the complexity, the power system safe operation problem is increasingly prominent. Frequent blackouts at home and abroad not only cause huge economic loss, but also affect the social stability seriously, arousing all electricity scholars’extensive attention to the safe and reliable operation of power grids. With rapid growth of demand for electricity in our country, and the implementation of the west-east electricity transmission project and the national networking strategy, Chinese power grid will become one of the largest and the most complex in the world, which improving power grid’s reliability and ensuring its safety have become the urgent problems. Therefore a comprehensive risk assessment and safe pre-warning for grid is of great significance. In view of this, this paper carries out a series of studies on the power system risk assessment and safety warning of the grid containing wind power. The main work is summarized as follows.This paper studies three phase of power system safety assessment, analyzes the characteristics of several kinds of power system reliability assessment method, determines that the risk assessment method in this paper is Monte Carlo method, also studies the theory of utility function, improves the failure consequence severity model that considers load important degree and voltage grade which makes the model accord with the practical situation of power system, improves the existing risk assessment quantitative method of hai’nan power grid which eliminates the shelter phenomenon, proposes the safety warning grading algorithm based on the risk assessment, studies the failure probability grading algorithm based on the fuzzy C-means clustering method because power system risk assessment is affected by the failure probability and failure consequences severity, proposes failure consequence severity grading algorithm based on fuzzy inference principle, obtains the security warning grading of the system through fuzzy operator, establishes the wind speed forecasting model based on the time series-state transition method and the wind turbine output model considering the wake effect.Use MATLAB software to compile by the algorithm program, and IEEE-RTS79test system to analyze the system risk when wind farm connects to the grid in different ways and the same capacity of wind farm replace conventional generator, verifying the validity of the method proposed in this paper. The simulation results show that the wind power direct access to the grid enhances the risk indicators and warning system level, component failure rate has less effect on the system warning grading, and the system security level reduces as the load level enhances.