Research And Implementation Of Voltage Fluctuation Detection Algorithm Based On Three_Phase Power Quality Analyzer

With the rapid development of economy in our country, the pressure of power system increased year by year, the resulting problems of power system also gradually increased. In recent years, a large number of nonlinear loads and volatility loads running in the power system caused the instability of power grade, voltage fluctuation and flicker. In addition, the reclosing operation of circuit in power supply system will lead to voltage sag, and the asymmetric short-circuit grounding can cause voltage swell. Such kinds of voltage change events will seriously affect the industrial production, bring unnecessary loss. Therefore, we need to measure various kinds of voltage fluctuation parameters accurately.In all kinds of voltage fluctuation parameters, flicker is of great importance and difficulty in its detection. The implementation process of traditional flicker detection method is relatively complex. In order to achieve the measurement of kinds of voltage fluctuation parameters in power quality analyzer at the same time, more advanced discretization flicker detection method need to be used, and the optimization of the method is needed in order to get better testing results. Since the test specification, processing cycles and data quantity are all different for different voltage fluctuation parameters, so there are still many difficulties in achieving the test of different kinds of parameters at the same time in a three-phase power quality analyzing system. Therefore, in this paper, the voltage fluctuation parameter detection methods are analyzed and implemented, and the flicker detection and realization method is mainly studied.First of all, the voltage fluctuation and flicker detection methods are researched in this paper. Detection methods for other voltage change parameters are studied and determined with the combination of the IEC standard and national standard.Secondly, this article focused on the study of discrete flicker detection method, analysised its theoretical basis and implementation process. Through the analysis of existing flicker detection methods, the deficiency is found and improvement methods are put forward. The optimized plan for the discrete flicker detection method is put forward. To reduce the interpolation error, volatility curve resolution is increased and higher operation points are used. To reduce transmission and quantization error, higher quantitative figures are used. Sampling from the zero-crossing point of the fundamental wave and correcting the theory error is of great importance. The simulation fresults of optimized discrete method and IEC method show that the maximum error of instantaneous flicker from 0 to 25 Hz reduced from 11% to 1%Then, the three-phase power quality analyzer software system is designed and implemented in this paper. Data acquisition is realized in the FPGA, while all parameters are calculated in DSP, and handed over to ARM for display purpose. Detection methods of voltage change parameters are designed in detail and data transmission process is designed from the perspective of data transmission.Finally, voltage fluctuation parameter detection method is verified in the platform of three-phase power quality analyzer. Verification results show that the instantaneous flicker detection error is within 2%, far higher than 8% of the IEC standards. Power supply voltage deviation, surge, plunging and interrupt detection errors are within 0.2%. This article also discusses the shortcomings of currently used method, proposed the next research direction.