The Research On Monitoring System Of Power Quality

With the development of modern industry,due to a lot of power electronic devices and nonlinear load widely used in the power system,power quality issues have become prominent increasingly.Now,our research focus on power quality in some areas,such as harmonic of public grid,frequency deviation of electronic systerm,allowed deviation of provided voltage,allowed fluctuations deviation of provided voltage.In western countries,indicators of power qualitaty which are monitored not only contain all the indicators of our country,but also contain many other indicators such as long continued times and temporarily status of voltage and so on..In this txet,power quality analysis and research are focused on the analysis of harmonic.Firstly,some concept of the basic parameters is given to us,such as average value of voltage,effective value of voltage,deviation of voltage,deviation of frequency,levels of armonic and distortion of voltage.The theoretical basis of the algorithm of the fast fourier transform is described in detail.Some measuers are taken to solutive the signal when the frequency of voltage is not synchronous,which can get the better result of the parametersAccording to the requirement of power quality monitoring system,the appropriate hardware and software are designed for it.S3C2440 is the most important chip of the hardware system,which is composite of the circuit of signal condition,the circuit of data acquisition,the circuit of serial port and the circuit of storage devices. Software is composite of drivers program,applicate program and set up embedded software platform.Drivers program contains such as analog to digital and serial device driver for linux.In order to improve the real-time of the systerm,we deal with it by some processes.They contain procession for the basic electrical parameters,procession for dealing with harmonic and the procession for communication.Then designer the graphical interface with qt,which is convenient to observate datas for users. At last,a simulation of the input waveform should be given to get the input waveform amplitude frequency response curve.Amplitude is 3.3,the input of voltage conditioning circuit was give a square wave with frequency of 50Hz,the theoretical value was compared with measurement data.we find that this systerm can meet the requirement.