| It is very significant that accurate and quick measurement of the electric power parameter for realizing the automation of power network dispatching and guaranteeing the safe operation of power network. With the development of modern power electronic technology, nonlinear loads are extensively applied in production and life.Their nonlinearity, impact and imbalance make power quality worse and worse. Electric power parameters become very important for people to grasp power supply line state and appraise electric quality. Measuring electric power parameters by digital signal processing technology has superiority in improving measurement precision and real -time performance. At the same time, digitization measurement makes the measurement system more intelligent.First, this paper introduces the development status and background of electric power parameters test instrument overall.The paper expounds the measuring principle of frequency, harmonic, voltage, current and other electrical parameters in detail. In this paper, a method based on interpolated FFT algorithm is presented to measure the power system frequency. Then the simulation results are compared with the measuring results of Fourier algorithm. Aiming at the spectrum leakage and picket fence effect of FFT algorithm in harmonic analysis, this paper expounds the corresponding resolvent and adopts the double spectrum lines interpolation algorithm based on improved FFT. This algorithm is compared with the FFT algorithm by simulating. This paper adopts the indirect measurement algorithm for the reactive power measurement through the comparison of simulation results.Then the overall design scheme for the electric power parameters test instrument based on DSP is introduced. The instrument consists of two main parts: data acquisition and processing system, data display and storage system. This paper mostly complete the hardware and software design of the data acquisition and processing system. The hardware part mostly includes ADC circuit, processor and peripheral circuit, memory expander circuit, logic control circuit and communication circuit. TMS320VC5502 which is the product of TI is adopted as the main processor. The software part mostly consists of main program, data acquisition, data processing and communication module's procedure design. This instrument can measure voltage, current, frequency, power factor, active power and reactive power, apparent power etc. It can realize real-time measurement and analysis of harmonic, measure the harmonic ratio and distortion from the second harmonic to the twenty-fifth harmonic.Finally, this instrument hits the expectant design target on the whole by integrally testing. |
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