Risk-based Security Analysis And Preventive Control In Power System

The connection of power grid and the development of power market have changed the power system into a bulk system. The operating conditions are more unpredictable and the control is more complex. The conflict of security and economy is more serious. Some accidental contingencies may break down system running and render over load, low voltage, voltage collapse, and even cascading fault. Hence, it is important for power system security to analyze power system risk and adopt some preventive control in normal state. However, the traditional methods cannot reflect the probability of power system and cannot trade off between security and economy. The risk method makes it possible to improve the performance of security analysis and preventive control on bulk power system. It is one of the hot points in current power system research.In this paper, risk theory is applied into power system security analysis and preventive control. Risk modeling, valuing and decreasing are the main areas of the research. The latest parallel compute and artificial intelligence are combined with the risk theory. The power system security alarm and decision system is completed.The main security analysis methods are introduced and their defects are pointed out. It is the reason why risk is used in power system. The concept of risk and its use areas in power system are introduced. The strategic power infrastructure defense system is introduced also.Some problems of power system static security, such as over load, low voltage, voltage collapse, cascading fault, are researched based on risk theory. For over load research, some main factors about over load are considered, and appropriate severity function is adopted, finally the over load risk model is built. For voltage research, low voltage problem and voltage collapse problem are separated, and corresponding models are built respectively. For cascading fault research, the mechanics and process are explained, a set of risk index on cascading fault are used to reflect the risk of cascading fault from different aspects.Based on the risk index, a method to reduce system risk and improve system security is provided. Optimal power flow based on risk is used in this method. Its object is to reduce risk. By the optimal results, power system states are changed to reduce risk value and improve security level. This method can prevent over load, low voltage, voltage collapse and cascading fault effectively.To improve the performance of the provided method, artificial intelligence is used for its merits on dealing with complex, non-linear, and uncertain problems. To reduce the computing time, parallel compute based on PC cluster is used for its easy implementation and low invest cost. At last, the sum is made and the future work is point out.