| With the development of distributed network technology, extensive using of power electronic devices in micro power grid and the user access to a large number of nonlinear loads, produce a large number of harmonic and power quality problems such as voltage distortion, so ensure the security of power quality is one of the premise of the application of micro network system security. The premise is to solve the problem of power quality for power quality comprehensive, real-time and accurate detection, to provide improvement scheme, to strengthen preventive measures. This paper mainly studied the main job has two aspects, on one hand, in order to realize the distribution network of the multipoint real-time detection of power quality and networking complex problems, design and research the three-channel power quality detection device. And on the other hand, in view of the influence on power quality harmonic, design of the filter to restrain the harmonics and reactive power compensation filter, and establish the simulation model, simulation test, this paper has done the concrete work is as follows:(1) By reading lots of related literature, according to the analysis of the distribution at home and abroad network for the actual demand of power quality monitoring system and inspection standards formulated by the state, through analysis, comparison, designed and implemented with PIC series single chip as the processor and ADE7880sampling chip three-channel power quality detector to achieve the distribution of weak network multi-point detection of power quality.(2) After determining the design of the overall design scheme, combining with the current widely used embedded and field bus technology, it was introduced to the power quality detection device, which for the design of the overall structure of the hardware layout: Including the data acquisition module, the SD card data storage module, the I2C interface circuit module, the microprocessor minimum system module and peripheral circuit design, and the design of the sampling signal conditioning circuit chip peripheral circuit design, etc., for realize the collection of power quality parameters.(3) After in the design of the hardware circuit, the power quality detection system software design use Mplab as development tool to design the main module, SD card driver module, serial communication module, and data communication protocol driver module. And use Visual C++as development tool design of power quality monitoring system PC application, has realized between upper machine and lower machine device of RS-485communication and data transmission.(4) Compare various harmonic suppression and reactive power compensation measures of harmonic detection algorithm, the advantages and disadvantages of the current tracking control technology, determine the harmonic detection algorithm on the basis of instantaneous reactive power ip-iq and hysteresis current tracking control of the shunt active filter for harmonic suppression and reactive power compensation effect on the simulation analysis, set up in matlab simulink platform of various modules of the simulation model and optional parameters.(5) With motor as the test load, design of power quality detection system for testing, and the test results comparison and analysis with the measured results by FLUKE5000power quality monitor, to verify the effectiveness of the device design and accuracy.(6) Use three-phase nonlinear load produces about30%of harmonic distortion rate as a simulation test conditions for the analysis of simulation results, can be obtained after the system put into active filter of the three-phase current harmonic distortion reduction to about2.6%, detect the content of the fundamental harmonic distortion rate of about1%, achieved good harmonic suppression effect and dynamic reactive power compensation, verified the effectiveness of the harmonic detection algorithm and the effectiveness of the hysteresis current control, and the correctness of the simulation model and the active filter design. |
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