Research On Control Strategy Of Soft Open Point In Active Distribution Network

New energy sources such as photovoltaics and wind turbines are continuously connected to the distribution network.Distributed Generation(DG)technology has become increasingly mature,and the proportion of renewable energy in the total power generation has also continued to increase.However,problems will follow.The diversity of DG and the diversification of user needs will aggravate the complexity of distribution network power flow,and seriously affect the power supply reliability of the distribution network.Faced with problems such as increased line loss,branch current overload,and node voltage overruns in the distribution network,traditional control methods can no longer meet the precise control of the distribution network voltage.Therefore,in order to meet the actual operation requirements,the intelligent soft switch(Soft Open Point,SOP),as a brand-new primary flexible power distribution device,replaces the previous tie switch or section switch.Compared with the frequent operation of switches before,SOP can realize accurate transmission and control of active power by imposing appropriate control strategies,which also reduces network loss to a certain extent.In this way,the distribution network can operate more flexibly and stably.Based on this,in order to discuss the control strategy of intelligent soft switch in active distribution network,the article involves the following points:(1)First,this article analyzes the new energy forms in the active distribution network,mainly wind turbines and photovoltaics,and after establishing corresponding mathematical models,discusses the relationship between environmental conditions,climate and other factors and output.Then it introduces the impact of distributed power generation on the distribution network,including voltage quality and network loss,when distributed power generation is connected to the distribution network,and analyzes the impact of SOP access on distributed power generation.This chapter provides a model for subsequent chapters.Support.(2)Secondly,for the convenience of research,this article uses SOP based on Back-to-Back Voltage Source Converters(B2B VSC).In order to establish a dynamic model of SOP,three types of SOP are given.Solving methods under the control modes Udc Q,PQ and PUac.In order to establish the mathematical model of SOP,its dynamic mathematical models in the three-phase static coordinate system and the dq rotating coordinate system are respectively analyzed.Through the analysis of the model,SOP adopts a double closed-loop control strategy,which lays a good foundation for the subsequent dynamic analysis of SOP.(3)The active distribution network model with SOP is established,the optimal power flow optimization result is used as the control variable,the improved particle swarm algorithm is used to solve the active distribution network based on SOP,and the power of SOP is adjusted to meet the current operating state of the system.Finally,in order to verify the practicability and effectiveness of the built model,a numerical example analysis is carried out under the IEEE33 node.It was found that the intelligent soft switch can restrain the voltage fluctuation caused by the source-load randomness to a certain extent,so that the power grid can operate safely and economically.