Research On Risk Tracing And Control For The Whole Process Of Power Grid Dispatch Considering Identification Of Critical Lines

With the increasement of scale,complexity and uncertainty in power grid,the reliability of electricity power system operation is facing a lot of challenges.On the one hand,fault of critical transmission lines in power grid with chain reaction will cause load shedding and even blackout.On the other hand,in face of more and more complex and large-scale power grid,electricity power dispatch,which is crucial to ensure power grid reliability,is confronted with big threat.This paper will try to trace and control risks of the the whole process of electric power grid dispatching,based on the identification of critical transmission lines in power grid.It is structured as followed:At the beginning,transmission betweenness of transmission lines is proposed and applied into identification of critical lines.Since abundant reactive power support is the base of voltage stability,transmission betweenness considering the effect of reactive power flow can identify critical lines that are important to voltage stability.Successive faults of critical lines can destroy transmission corridors of active and reactive power flow.On this occasion,some loads have to be cut off to maintain frequency and voltage stability.So,load shedding based on optimal power flow is calculated as the evaluation index to verify that transmission lines with high transmission betweenness are critical indeed in power grid.The results of IEEE 39-bus system and IEEE 118-bus system show that transmission betweenness is superior to flow betweenness in identification of critical lines that influence voltage stability,and the identification method of critical lines in power grid based on transmission betweenness is reasonable and effective.Next,this paper put forward a technology of risk tracing and dynamic control for the whole process of electric power grid dispatching that includes mid-short term,day-ahead and real-time periods.Traditional risk assessment and control methods focus on the risk condition in a dispatching period,neglecting the influence of the former period on the latter,so they cannot tell comprehensively the risk level of the whole dispatching process,or provide risk control advice adapted to the whole dispatching process.In view of the present disadvantages,this paper put forward a technology of risk tracing and dynamic control for the whole process of electric power grid dispatching that includes mid-short term,day-ahead and real-time periods.This technology can significantly increase the reliability of electric power system by monitoring and controlling risks of the whole process of electric power grid dispatching.At last,based on studies mentioned above and considering the reality of power system,a software system of risk tracing and dynamic control for the whole process of electric power grid dispatching is developed.This paper will introduce the main function,hardware structure,software structure and data structure of that software system.By tracing and controlling risks of the whole process of electric power grid dispatching,this software system can provide risk avoiding strategies and enhance depth and width of risk prevention of electricity system.