The Applied Research Of On-line Monitoring Device For Power Quality Of Distributed Power

With the rapid development of distributed power grid,the proportion of high-power power electronic converter device in the power system load becomes larger and larger,bringing unprecedented impact and pollution to the distributed power grid and resulting in a lot of power quality Problems.It seriously affects the power quality and safety stability of the grid.The changing structure of the grid makes the traditional monitoring system unable to meet the new development needs,urging enterprises or R & D personnel develop power quality online monitoring device which is adapt to the distributed power grid.Therefore,combining the characteristics of distributed power quality and functional requirements and drawing on the practical results of existing power quality monitoring,this paper conducts the analysis and research as followings:(1)Firstly,the background and significance of this research are introduced.Then,the research status and existing problems of the online monitoring system of distributed power quality and the topology of the distributed power quality monitoring system are discussed;(2)The mathematical model of distributed grid is established.The distributed power grid simulation system is built by PSCAD software.The influence of DG grid-connected location and capacity on power quality is analyzed,which provides a reference for designing distributed power quality online monitoring device;(3)This paper briefly introduces the basic concepts of power quality parameters and relevant national standards,which provides the basis for the design of software and hardware for distributed power quality monitoring devices;(4)The hardware design part gives the system design scheme based on DSP + FPGA + ARM,including signal acquisition circuit,signal conditioning circuit,digital signal processing circuit,human-computer interaction and communication circuit.For each module,given a detailed hardware selection and circuit design,including the internal hardware structure,interface circuit design,power management circuit design and so on;(5)The software design part introduces program Design of several modules,including: main program design,AD sampling interrupt subroutine design,DSP data processing main program design,FFT subroutine design and power quality parameter measurement algorithm,communication interrupt service subroutine,the ARM main program design,spectrum leakage improved algorithm design and man-machine interface design.(6)Through the piconet test platform,it is verified that the device is suitable for distributed grid system.The basic functions and indexes of the system have reached the relevant national standards.