Research On Smart Grid Composite Power Quality Controller

Because of the development of modern industrialization,the use of nonlinear,unbalanced and impact load become more and more popular,it brings harmonic and reactive power problems,which are seriously affected the efficiency of distribution system and the quality of power supply.In order to ensure the safe operation of smart grid and satisfy the consumer's requirements,State Grid proposed the development of Composite power quality controller device.The device not only can compensate harmonic and reactive power independently,but also can solve the problems at the same time.With the development of this research,many researchers are focusing on algorithm,detecting methods and compensation control strategy.Firstly,this paper introduces the operation principles and topological structures of the Composite Power Quality Controller.Based on conversion relations between dq rotating coordinate system and abc coordinate system,it builds mathematic models of harmonic current compensation side,reactive power compensation side,and DC energy storage side.Secondly,this paper mainly studies harmonic and reactive currents detecting methods.To solve the control accuracy caused by harmonic detection delay,it proposed an improved harmonic current detection method based on TLS-ESPRIT algorithm analysis.It also gives a new quick method for detecting reactive currents by using dq rotating coordinate system.Above all,it proposes current tracking and SVPWM control strategies based on the detecting methods.Finally,this paper supplied calculation models of major parameters of the device.In order to evaluate feasibility and effectiveness of the control strategies,it establishes simulation model of Composite Power Quality Controller in Matlab/Simulink.Simulation results show how the device solves the composite power quality problems in steady and transient states of the electric power transmission network and show that by using the device the current harmonics is 0.06%,meanwhile the load side voltage operates in safe range.