Fault Chain Model And Risk Assessment Of Power System Based On Bus Load Rate

Power system,involved in national security and socio-economic stable operation,is an important infrastructure.Which blackout will cause incalculable social and economic losses.This means that the power system not only needs to ensure the normal,safe,reliable,high quality and economic power supply,but also should enhance its ability to resist the external disturbance caused by extreme disturbance to reduce the loss.In this thesis,a bus voltage stability evaluation system and a new method,based on active and reactive power margin,are proposed.And a new index is proposed to evaluate the bus voltage stability.This index can effectively reflect the relationship between load rate and voltage stability margin.The corresponding case study also proved that the proposed system can provide decision support for scheduling operations of power system.Then,based on the fault chain theory,the above-mentioned bus voltage stability evaluation index is taken as one of the factors that affect the initial segment and the middle segment of the fault chain,and a new fault chain model of power system is proposed.In addition to the bus load rate,the factors affecting the initial segment include the historical statistical failure rate,the line load factor and the correlation coefficient.Factors affecting the middle segments also include the trend of power flow,line overload margin,the degree of influence between links.Besides,an example of the IEEE 39-bus system is analyzed,and the results shows that the fault chain model is reasonable.Finally,based on the proposed fault chain model and the risk assessment theory,the concept of sensitive line is proposed in this thesis.The sensitive line includes two situations:if not consider the load shedding and other emergency control measures,line breaking will lead to the system disconnection directly;line breaking will trigger a high risk fault chain.Based on the proposed sensitive line set,power system scheduling can improve the capabilities of grid to prevent and resist the external disturbance caused by the accident.The simulation analysis based on the IEEE 39-bus system also proves the reasonableness of the proposed method.