Research On Performance Assessment And Optimal Placement Of Distributed Power Flow Controller

With the construction of large-capacity UHV transmission systems and the centralized access of large-scale renewable energy sources,the operation mode of the power grid is increasingly complicated,which poses a severe test for the power flow control.Utilization of Centralized FACTS equipment causes large construction area and high initial investment costs.Therefore,it has not been widely used in power flow control.The distributed power flow controller(DPFC)based on distributed AC transmission technology has the characteristics of flexible installation and easy expansion,which provides new ideas and directions for solving this problem.Therefore,evaluating the application effect of DPFC and formulating its configuration strategy are urgent problems for satisfying the requirements of power flow control and security operation.This paper mainly carried out the following specific work:(1)A novel constant capacity control model of DPFC is proposed and power flow equation with DPFC is derived based on the equivalent power injection method while considering its work principle and technical characteristics.The power flow transfer capacity and the static voltage stability of the system are selected as research targets.After that,the quantitative evaluation index of DPFC's efficiency are established respectively to evaluate DPFC's efficiency and analyze their influencing factors.The impact of DPFC access on the distribution of power flow and the static voltage stability of the system under different conditions are quantitatively evaluated based on the IEEE-RTS79 system.(2)In order to enhance system loadability and avoid the redundant configuration of DPFC,a two-stage optimal configuration method of DPFC is proposed which decouples it into two stages optimization problems.The first stage optimization model takes the system loadability as objective function and determines the maximum system loadability under the current grid structure considering the traditional power grid constraints and DPFC's physical and operational constraints;whereas the second stage optimization model takes the maximum system loadability obtained as a operation constraint to determine the optimal placement of DPFC in each line by optimizing the DPFC investment costs.Finally,the maximum system loadability and the optimal DPFC configuration are realized at the same time.(3)A multi-time scale coordinated scheduling method with DPFC is proposed to limit the wind spillage under the acceptable level with large capacity wind energy integration.First,the optimal configuration scheme of DPFCs is initially determined by stochastic method considering based on several scenarios.Combined with the obtained scheme,two sequential procedures divided into day-ahead and real-time scales are built including wind power prediction model considering its uncertainty.The day-ahead scheduling model determines the generating plan and real-time scheduling model corrects the generating plan considering the uncertainty of wind power and fast operation of DPFC.After that,the real-time scheduling schemes of wind power,generating units and DPFC operation are determined.Stimulation results in IEEE-RTS79 system illustrate the effectiveness of proposed method.In summary,the results of the performance analysis of DPFC and the proposed optimal configuration and operation control strategies can be effectively applied to power flow control and consumption of renewable energy.Therefore,it provides a technical reference for the practical application of DPFC.