Research And Design Of Electric General Parameter Monitor Based On ARM

In view of the needs to monitor electrical energy quality and govern the harmonic in the modern low-voltage electrical network, An new type of low-power, integrated electric network monitor meter is designed in this thesis, which merge the embedded technology, modern signal processing technology, virtual instrument technology. This system has realized to monitor the phase/line voltages of three-phase electrical network, currents, active power, reactive power, apparent power, power frequency, power factor as well as the 31 harmonics of three-phase voltages and current real-time.It is analyzed in this thesis that is the measure principle of electrical power system basic parameter based on microprocessor; The alternating current parameter of the signal to be measured is obtained through the sampling method, the data that via sampling from many points can reduce the impact of random error; To apply FFT in the wave analysis obtains the frequency range parameter of the signal via analyzing harmonic measure principle based on DFT and the FFT; The second-order anti-aliasing filter is designed in view of aliasing error of harmonic measure; The paper analyze spectrum leakage, stockade effect and the impact to harmonic measurement by these, spectrum leakage and stockade effect are caused by non-synchronous sampling and truncation to the non-time-frame signal; Discussed inhibitory action of the commonly used several kind of windows to the spectrum leakage, based on this chooses Haming windows to process to the sampled signal; DDS characterize the high accuracy frequency synthesis, so it is applied to sample the electrical network signal, that improve the synchronization of the sampling, meet the requirements of the system to measurement accuracy; The above-mentioned method need a lot of calculations, the microprocessor LPC2132 that is 32 bits based on ARM is used in the system to improve the system's data-processing capabilities and real-time; The switching power supply is used in the system to reduce the volume and raise the efficiency; The paper has completed the electric circuit design of data acquisition part,second-order anti-aliasing filter, frequency measurement electric circuit and the connection module.; Finally, introduced the software design part, mainly contained the process of data samping and the FFT program design; The PC software of system is designed to process the data of electric network, the software use the platform of Lab Windows/CVI 6.0, utilize the rich library functions of CVI, complete the data processing ,display and recording, and the dual-threaded pattern is used, that has completed display, order transmission and performance curve so on while the data sampling and processing.It is the prototype that is designed according to the above program after three time circuit modification and debugging software, it's main technical parameters meet the design requirements and pass the test in the laboratory, it is testing to govern harmonics of electrical power system in industrial site.