Research On Intelligent Electric Power Monitor

With the development of power electronic technology and the unceasing increasing of electric loads,especially those asymmetrical,impacting and nonlinear ones,these have made the network voltage and current waveform distortion,and made the frequency fluctuating nearby 50HZ.Moreover,due to the massively widespread application of control device and precision instrument based on computer system,it is getting higher and higher for the request of power quality.Therefore,the present power monitor has gradually not been able to satisfy the request of system performance.This research launches just about this background.This article has designed double CPU intelligent electric power monitoring system based on DSP and MCU chip through researching on the correlation theory and technology of power quality monitor.It uses AC sampling technique to realize the real-time measurement of electric power parameter,which provides the credible basis for the power quality's government.Firstly,this article summarized the research actuality and development trend of power monitor.Then it carried through the elaboration about the measure algorithm of the real-time effective value of voltage and electric current and other power parameter under the influence of high-order harmonic.It mainly provided the harmonic algorithm which combined the base parameter adjustable neural network with FFT.This can precisely analyze the integer harmonic and non-integer harmonic. Simultaneously,it has realized the high-accuracy measure of power frequency using the FFT algorithm of interpolation improvement.Then,it has provided the measure algorithm of transitory power quality disturbance based on the wavelet transformation. Using the fast wavelet transformation algorithm,namely Mallat algorithm measures and extracts disturbing signal,and made the simulation on the MATLAB environment,using the db4 and 3 criterion to make the wavelet decomposition and restructuring in order to detect signal,which validated the wavelet transformation to be able to realize the power quality disturbing signal accurate orientation.At the same time,it has provided the realization of FWT algorithm on DSP.Finally,it has realized the software and hardware design of intelligence power quality monitor.In this article,the hardware design used DSP and MCU double CPU structure, DSP using the high performance-to-price ratio 16 bits fixed point TMS320LF240A chip and MCU AT89C51 chip.Using dual-port RAM chip solved the data transmission question between DSP and MCU,and matched the suitable peripheral circuit to realize each function,mainly including data acquisition,data processing, man-machine connection and RS485 serial communication connection.It has realized various parts of electric circuit connection.This may fully display DSP digital signal processing function and MCU control supervisor function,and can raise the efficiency and performance of overall system.The software design used modular and programming method from the top,which caused the program structure clear and easy to maintenance and extended function,and reduced the possibility of making mistake.It has realized the design of various modules flow chart.This article summarized the reason of system disturbance and provided the corresponding anti-jamming facility of hardware and software in order to enhance the system's reliability.It made the summary and forecast of overall system.