Research On Feeder Flexible Interconnection Switch In Distribution Network And Its Power Coordinated Control

With the rapid development of distributed energy,the diversification of AC and DC load types,and the sharp rise of load power consumption,coupled with the backward design of traditional distribution network "closed-loop design,open-loop operation",the problems of unbalanced feeder load and heavy over load of distribution transformer become increasingly prominent,seriously affecting the safe and stable operation of distribution network.Relying on the development of advanced power electronics technology,building a flexible,efficient and reliable modern distribution network is an important way to solve the existing problems.As a key power electronic device to realize flexible interconnection of feeder in distribution network,flexible interconnection switch of feeder in distribution network can directly replace contact switch in traditional distribution network and be controlled locally or centrally.It can accurately regulate the active and reactive power of the feeders connected with it,make the distribution network organically combine the main advantages of radiation structure and ring structure,ensure the normal operation of distribution transformers,improve the reliability of distribution network power supply,and provide interfaces for distributed generators and multiple loads to access distribution network,and further improve the carrying capacity of distribution network.Firstly,the access mode of feeder flexible interconnection switch in distribution network is explained,and its typical topological structure and difference are briefly analyzed.The topological structure suitable for feeder flexible interconnection,renewable energy absorption and diversified load access in distribution network is given.Its working characteristics are analyzed,and the flexible interconnection switch of feeder in distribution network is explained.The function of power coordination control.Finally,the important modules of the flexible interconnection switch of feeder in distribution network are modeled and simulated,and their working characteristics are analyzed.Secondly,in view of the problems such as the number of feeder flexible interconnection switch ports of distribution network,the working state of each port is not fixed,and the coordination control is relatively difficult,the system operation is divided according to the operation state of distribution network,the load condition of distribution transformer,the critical power redundancy(or shortage)of system and the charge state of battery,and each working condition is elaborated in detail.The operation of each port of the system.At the same time,the mode switching criterion is added to ensure that all ports can be switched according to the set threshold under different operating conditions,so as to realize the stable operation of the system.The simulation model is built based on MATLAB/Simulink,and its results verify the correctness and effectiveness of the control strategy in the normal operation of distribution network.Finally,aiming at the coordinated control of distribution network in abnormal operation,the control strategies of AC port,photovoltaic port,battery port and load port are elaborated respectively,and the power coordinated control strategy of flexible interconnection switch for distribution network feeder is proposed.Under the power coordinated control strategy,each port can change the operation mode according to the given information of the system,realize the reasonable interaction between the power ports,maintain the load balance of feeder,non-heavy load of distribution transformer and uninterrupted load supply of distr ibution network,and realize the stable operation of distribution network in abnormal operation state.The simulation model is built based on MATLAB/Simulink,and its results verify the correctness and effectiveness of the control strategy in the abnormal s tate of distribution network.