Study On Power System Probabilistic Risk Assessment And Its Application

With the rapid development of economic society and electric power demand, a national and interconnected power grid is formed in China to improve the further utilization of coal, hydro, wind, solar energy and other resources, which insures the optimal allocation of electric energy across the country. However, the random and intermittent characteristics of renewable energy integrated to system brings an extra risk to system operation. In addition, the electric vehicles have been widespread concern in energy and environment crisis. A large population of electric vehicles connected to the grid can also bring more uncertainties to system planning and operation. In this paper, power system risk assessment method and its application are firstly proposed. And the impact of the integration of renewable energy and electric vehicles on system security is analyzed by risk assessment method. Four research fields in this paper are concluded as follows,Firstly, the risk analysis method considering the constraints of static and transient security in power system planning is studied based on traditional risk assessment theory. In static risk analysis, a power flow control method based on static sensitivity is proposed, and then the load curtailment is used to calculate the adequacy of transimission system. In transient risk analysis, the angle stability criterion and control method based on trajectory sensitivity is adopted to calculate the transient angle instability risk. Finally, the risk analysis method is used to some practical planning work.Secondly, the N-k risk analysis method based on the post-outage power flow transferring is presented, where the impact of different load levels and multiple failures on system risk is considered, at the same time, the impact of random and intermittent characteristics of wind power is also involved. Finally, risk analysis method is used to optimally select the grid-connection schemes of wind farm, while the storage capacity configuration scheme for wind farm is optimized.Thirdly, a power shortage compensation model of distributed generation after outages is proposed. Further, a hierarchical risk assessment is presented, which considers the supporting ability of distributed generation after the power loss happens in transmission system, and the bidirectional power flow caused by the distributed generation. The modified risk analysis method insures the resuts of risk assessment more reasonable.Finally, a bidirectional charging power control of electric vehicles based on time series charging model is presented, and we further analyze the impact of electric vehicle charging and discharging power management on generation system adequacy. After that, an electric vehicle charging power self-management model is constructed based on the concept of virtual power plant, and we further analyze the impact of electric vehicle charging power management on generation and transimission system operation risk. The research can provide some valuable references to system planning and operation with the demand to consider the charging behavior of electric vehicles.