Study On The Coordination Of Preventive Dispatch And Restorative Dispatch In Extreme Weather Events

The rapid consumption of fossil energy has triggered serious global climate change,which has led to the frequent occurrence of extreme weather events in various countries and regions around the world.Extreme weather events are characterized by wide coverage and huge destructiveness,making the power system face the serious challenge of maintaining the reliability of power supply during such events.Taking the initiative to overcome this challenge is of great significance to ensure the economy of social development and the stability of power system operation.From the time scale,power systems undergo a multistage process during extreme weather events,including preventive dispatch stage,emergency dispatch stage,and restorative dispatch stage.At the same time,the resilience level of power systems will fluctuate in stages.Combining the concept of resilient power system,this thesis investigates a robust optimization method to coordinate preventive dispatch,emergency dispatch,and restoration dispatch,aiming to develop a proactive operation plan to reduce the overall load loss and resilience loss caused by extreme weather events on the AC transmission system.Based on the proposed method,the complete resilience trapezoid curves of three dispatch stages in extreme weather are calculated.In this thesis,we first analyze the potential cooperativeness among the preventive,emergency and restorative dispatch stages under extreme weather conditions,as well as the game between them and extreme weather.Then,the overall objectives,decision sequences and interactions of aforementioned dispatch stages are determined.To coordinate three dispatch stages,a novel hierarchical defender-attacker model is designed,and a research framework for a multi-dispatch coordinated strategy in extreme weather events is established.Second,to deal with the challenge of solving the two-stage robust optimization problem with nonlinear terms in the conventional AC power flow model,this thesis develops a piecewise linear AC power flow model that takes into account line switching and load shedding by the piecewise linearization method.Based on this linearized model,preventive,emergency and restorative dispatches are modeled as system defenders.With the discrete uncertainty set,the extreme weather event is modeled as an external attacker.Subsequently,a complete model of multi-dispatch coordinated strategy is formulated through the hierarchical defender-attacker model.Finally,the proposed coordinated optimization model is solved by the nested column-constraint generation algorithm.Case studies with modified IEEE 6-bus system and the IEEE 118-bus system verify that the robust coordinated strategy can effectively reduce the overall outage loss and load shedding cost of transmission systems during extreme weather events.Meanwhile,based on the calculated robust resilience trapezoid curve,the resilience loss is analyzed,it is verified that the coordinated optimization method is conducive to decreasing the overall system resilience loss.Moreover,by performing the inference-based line hardening analysis for the line outage scenarios in different load loss conditions,the proposed method can also identify critical lines in the area affected by extreme weather events.