Research On Star Chain STATCOM With Auxiliary Power Loop

As a new generation of reactive power compensation device,the star-chain static synchronous reactive power compensator has the advantages of fast adjustment speed and easy modular expansion.So STATCOM plays an important role in the power quality management of medium voltage distribution networks.However,the traditional star-chain STATCOM has almost no ability to compensate unbalanced current.This paper proposes a star-shaped chain STATCOM with a interphase power path and its control method,which can complete the current compensation function for any imbalance.And can expand the application field of STATCOM.This article analyzes the operation principle of the traditional star STATCOM.The mathematical model is established on the abc stationary coordinate system and the dq rotating coordinate system.Based on the mathematical model of the dq rotating coordinate system,direct current control method and indirect current control method were analyzed for STATCOM.And direct current control method is used to control the operation of STATCOM.For reactive current detection,the ip-iq detection method was researched and verified in Matlab / Simulink software.In order to solve the problem that the traditional star STATCOM has weak compensation ability for unbalanced current.This paper presents a star-shaped STATCOM with interphase power path.The improvement of the traditional star STATCOM on the topology is to add two intermediate frequency power exchange paths between the three phases.Based on the direct current control method,dual-frequency carrier phase shift control is used to make the intermediate frequency current flow in the power exchange path to balance the power between the phases of the device.In Matlab / Simulink software,the simulation is compared with the traditional star STATCOM.Simulation results show that the new STATCOM can compensate for any unbalanced current.Through analysis and calculation,the parameter selection method of the new STATCOM connection inductance,DC-side capacitance,and the inductance,capacitance and resistance of the interphase power path is given.Finally,an experimental platform with a semi-physical simulation system as the core is set up for experimental verification.The experimental platform uses hardware-in-the-loop simulation software as the hardware part and DSP +FPGA as the software part of the core controller.Experimental results show that a star-shaped chain STATCOM with a interphase power path can complete reactive power compensation for any imbalance.