Research On Detection Method Of Flicker Parameter Using The Analytical Mode Decomposition Based On Spectral Correction And Application

Voltage fluctuation and flicker is one of the power quality problems that seriously disturb the normal and efficient operation of power system relay protection devices and electrical equipment.In recent years,new energy sources such as wind power,photovoltaic power and biomass power,which are intermittent and complex,have been connected to the grid.It has a fluctuating effect on the power grid,resulting in increasingly serious voltage fluctuations and flicker problems and consequently becoming a new flicker source.High-precision detection of voltage fluctuations and flicker can provide scientific basis for the control of voltage flicker.Firstly,research background and significance are elaborated.Then domestic and international standards and detection method of the voltage flicker are introduced respectively.At last,the domestic and international development status of flicker is detailed subsequently.Focusing on the deficiency of current flicker enveloping extraction method that suffered from poor accuracy and low efficiency,an analytical mode based method is proposed to decompose and extract the flicker envelope after studying deeply on the mathematical model for voltage flicker-modulated wave.To acquire the synchronized signal of grid voltage,the process of obtaining the synchronized signal of the fundamental voltage implemented by the multi-sampling method is deduced in detail.The paper deploys voltage synchronized signal deduced from multi-points method to apply detection on flicker signal.Through synchronous detection,the amplitude modulation wave flicker signal is converted into a linear combination of the flicker envelope signal and the double-sideband amplitude modulation signal with a frequency ranges from 65 Hz to 135 Hz.Then the high frequency components are filtered out by analytical mode decomposition,which is deduced specifically.At last Single-frequency flicker signals and multi-frequency flicker signals are used for simulation experiments and analysis of envelope extraction algorithms.Following the IEC recommended voltage flicker detection principle,the flicker detection process is analyzed and simplified.Based on the analysis of the good sidelobe characteristics of the 6-term cosine window,the paper combines the analysis-mode decomposition and flicker envelope extraction method,proposes and establishes the voltage flicker parameter estimation method improved by the analysis mode decomposition 6-term cosine window four-spectral interpolation and FFT spectral analysis.The simulation experiment was implemented in six cases:single-frequency flicker signal,multi-frequency flicker signal,frequency fluctuation of grid voltage,harmonics contained in flicker signal,interharmonics contained in flicker signal,and noise in flicker signal.The simulation results show that our method achieves a high measurement accuracy and can effectively overcome the interference of harmonics and interharmonics,frequency variation of fundamental wave and white noise on measurement results.The flicker detection method presented in this paper,the flicker detection method recommended by IEC and the flicker detection method based on S-transformation are used to simulate the flicker value.The results show that the proposed method is compared with the IEC recommended method and The S-transform method has a higher detection accuracy when flicker values are calculated for flicker signals containing a single frequency fluctuation component.Considering the development of voltage flicker detector management platform,the paper deploys the high-performance ARM processor MK66FN2MOVLQ18 as core unit to fulfil management unit and concerned circuit is designed.Then the minimum system of the management system,power module,Ethernet interface module,and storage interface module are introduced afterwards.The management unit of the voltage flicker parameter detector is embedded with the embedded real-time operating system MQX in an attempt to realize a robust and reliable management,then flicker value calculation software implementation flow,flicker parameter management task design,communication module software design,human-computer interaction module software design are introduced in detail.Finally,the research work and innovation results of this thesis are summarized,and the future work that should be carried out in the next stage is indicated.