Research On Risk Assessment Technology For Integrated Transmission-distribution Power System

With the development of economy and society,the requirements for resource allocation capacity,energy utilization efficiency and environmental protection have increased.A large number of new types of electrical equipment such as distributed generators and energy storage have been integrated into the distribution network,which not only alleviates the scarce problem of energy,but also brings great changes to the traditional distribution network.The operation mode of the distribution power system is more flexible,and the distribution network changes from the traditional passive network to the active distribution network.The distribution network’s impact on the operation economy and safety of the transmission network is gradually increasing.The mode of coordinated management of the integrated transmission-distribution network is constantly explored and improved.Conform to the trend of power system control mode,this paper conducts research on risk assessment and control of the integrated transmission-distribution power system.The specific works are as follows.Firstly,the observability and controllability of the distribution network are analyzed.Based on the construction model of the integrated transmission-distribution control system,the necessary of transmission-distribution coordinated energy management is studied to solve power balance problem,power flow blocking problem and network voltage problem.Furthermore,the risk assessment mode that the transmission and distribution network are split is found to be no longer reasonable.The risk assessment method for integrated transmissiondistribution power system needs to be studied.Secondly,a risk assessment method for integrated transmission-distribution power system is proposed.Based on the power regulation capability of the distribution network,the active power and reactive power grading adjustment models are used to calculate the fault consequences of the transmission network.The load regulation requirements of the transmission network are transmitted to the distribution network,and the result of load shedding in the distribution network is the final state consequence.With this method,both the risk assessment of the transmission network takes into account the flexibility of the distribution network and the impact of the transmission network fault on the distribution network operation risk is considered.Finally,considering that the risk assessment of power system is carried out to guide the adjustment of the operation mode in time,in order to control and limit the system operation risk,the two-stage coordinated risk-based dispatch model for the integrated transmissiondistribution power system including day-ahead and real-time dispatch is studied.Based on fault probability prediction,the day-ahead risk-based dispatch is to coordinate the resources in the transmission and distribution power system,formulate hourly power generation plans and load curves,and provide basic operating points for the real-time dispatch.Real-time risk-based dispatch tracks the dynamic changes in risk factors and equipment operating conditions,and optimizes the operation point of the system on the basis of day-ahead dispatch.The two-stage risk-based dispatch coordinate the control of the transmission network and distribution network resources to reduce operating costs and losses,and realize the risk decision and control of the power system.