Research On Application Of SOP In Distribution Network

As an important part of the power grid,the distribution network plays a significant role on production and lives.Nowadays,in the distribution network,the application of power electronics technology is showing a rising trend.As a new type of power electronic device,soft open point can replace traditional tie switches,besides,it can be used among the feeders to realize flexible interconnection of the distribution system.In addition,SOP can control the power flow,improve the operational reliability and power quality of the power systems at the same time.The purpose of this paper is to develop the application potential of SOP to improve economic efficiency of power systems,the main contributions are as follows:（1）three topologies of SOP are listed and compared,then,BTB-VSC equipment is select as the main research object of the whole article.The basic structure model of SOP is established through PSCAD,the mathematical model and power transmission characteristics are analysed from the three-phase stationary coordinate system and synchronous rotating coordinate system.Based on that,the outer-loop control module and inner-loop control module of SOP are analyzed,besides,the model of P-Q control,U_dc-Q control and V-f control are built.The model is the foundation of analyzing the application of SOP in the distribution network;（2）A distribution network model is built with SOP,the dynamic response capability of SOP equipment is test in the distribution network,it verifies the effectiveness of the control strategy of the model.This paper study the power control ability of SOP in the normal operation state,meanwhile,the power recovery ability of the distribution network when the protection device operates due to a fault to form a power loss area.In this way,the ability of SOP is proved,it can provide power support for the power loss area and ensure the continuity of power supply.Furthermore,the SOP equipment has the isolation capability for faults and three-phase imbalance;（3）The application potential of SOP equipment is studied in view of the common three-phase unbalance in distribution network.By using Clark and Park transform,the SOP model under the three-phase unbalanced scenario of the distribution network is re-established.The positive and negative sequence components are separated by the forward and reverse rotation coordinate transformations,and the double frequency component is filtered by the notch filter method.The negative sequence current suppression control strategy is proposed to integrate the overall control strategy of SOP under the condition of three-phase imbalance.The corresponding model is built in PSCAD and the simulation experiment is carried out to verify the effectiveness of the proposed SOP control strategy in three-phase inbalance control.