Research On An Integration System Of Reactive Power Compensation And Harmonic Elimination For Middle-small Enterprise Distribution Network

The distribution network of the middle-small enterprise is characterized by serious harmonic pollution,which leads to the current reactive power compensator cannot be put into operation safely and the power factor is low,the power quality is poor.Therefore,an integration system of reactive power compensation and harmonic elimination for the middle-small enterprise distribution network(hereinafter referred to as “the integration system”)is presented and researched in this thesis,with the support of 2015 Wuhan Technology project(2015010101010013).This system with harmonic filter and reactive power compensation function can eliminate harmonic and improve power factor.The harmonic filter is switched on firstly,and then the reactive power compensator operation safely.The main works accomplished and the results in this study are as follows:(1)The topological structure of the integration system is designed.The integration system is consists of the harmonic filter subsystem and the reactive power compensation subsystem.And then the implementation steps are proposed.Finally these subsystem mechanisms are analyzed.The parameter setting method of the variable reactor,the filter capacitor and the compensation capacitor are presented.The control strategy of the reactive power compensation subsystem is put forward.The research results lay the foundation for the follow-up research work.(2)The simulation research of the integration system is completed.Firstly,the simulation model of the integration system is constructed by MATLAB/Simulink simulation tool.The system simulation schemes are proposed.The simulation schemes are including the reactive power compensation scheme,the harmonic filter scheme and comprehensive treatment scheme.Secondly,the main modules of the system are designed,such as the nonlinear load,signal detection circuit,impedance transformation circuit,capacitor banks and so on.Finally,the simulation data of the integration system is analyzed.The simulation results of these scheme showed that the harmonic filter subsystem must be switched on before the reactive power compensation subsystem.The system performance index,such as the power factor,percentage of the harmonic currents and total harmonic distortion(THD),meet the national standards.These research results lay the technical foundation for development of the integration device.(3)The scheme of the integration system is designed.The main circuit,operating circuit,the hardware circuit and software circuit of the control system are designed according to the topology of the integration system.The hardware circuit of the control system is designed using S7-200 PLC as its controller,including the hardware selection,I/O circuit,parameter collection circuit and pulse trigger circuit.The design of software circuit is including PLC control plan and the monitoring interface.Monitoring interface is designed by configuration software MCGS.These research results lay the foundation for the realization of the prototype and its industrialization process.The integration system can not only be applied to the new enterprise,but also combined with the existing reactive power compensation device for free through the interface circuit to meet the needs of different enterprises.Therefore,it makes a great sense to develop the integration system of reactive power compensation and harmonic elimination for middle-small enterprise distribution network,with practical application value and to reduce the cost of the enterprise.The system is expected to be applied in middle-small enterprises in the promotion and application.