The Research Of Grid Voltage Harmonic Monitoring System Based On FPGA

With the rapid development of global scientific and technological level, the GDPcontinues to improve, it has put forward higher requirements on industrial productionand the national life in the quality of the electricity power. A large number of nonlinearloads put into using, injected to the grid with different levels of harmonics,harmoniccontent as one of the important indicators of power quality in all aspects of gridtransmission, distribution, consumption and so on in each link, it will make a greatinfluence. To suppress the harmonic content, it has become an index evaluationtechnology for the power supply department in recent years. The first thing to do thework for the engineers is monitor the parameter value, as a reference for the subsequentinhibition.This paper is based on the FPGA development platform, use its parallel processingtechnology to monitoring the voltage harmonic, with the Xilinx company of Spartan-3Efamily XC3S250ETQG144main chip design grid voltage harmonic monitoring system,by using voltage transformer for civilian power220V AC grid sampling, and throughthe eight length A/D analog-to-digital conversion chip sent to the FPGA, using theHilbert-Huang Transform for every harmonic component of the decomposition andcomputation, to get the parameters of the information storage, display and sent throughthe communication module, etc.The system mainly consists of the following modules:FPGA core board unit, signal acquisition and conditioning modules, analog to digitalconversion module, Hilbert-Huang transform analysis module, the key control module,the display module and the circuit of communication module.Not only introduce the harmonic and its parameters are calculated based on therelated concepts, focusing on analysis of core-HHT transform algorithm, but alsoinvolves the general steps of FPGA design and VerilogHDL language features. Onhardware circuit design, hardware circuit of the whole frame structure is presented,detailed the hardware modules of chips and components used in parameter calculationprocess, and related resources on the FPGA core plate is introduced, and the overallschematic diagram, PCB design and so on. In software design, the paper summarizesthe overall flow chart, and the software diagram, detailed introduces the working flowof every module, and the specific configuration of some unit are described.The system is capable of2to19times the grid voltage harmonic voltage amplitude, each harmonic content ratio, harmonic content and total harmonic distortion rateparameters, after the result records is stored to the FIFO, by using control button, thedisplay in a total of eight male digital tube, while taking advantage of the RS232serialcommunication, and GPRS communication technology to send data information first bitmachine and the monitoring equipment.Finally, through testing of each module, get some test data of the system, it willmonitor the actual results and harmonic detection equipment in market to compare datato verify the feasibility of the system.