Optimal Control Method for Quasi-PR Grid-connected Inverter with Adaptive Harmonic Elimination

Abstract

The invention discloses a quasi-PR grid-connected inverter optimization control method for self-adaptive harmonic elimination. In view of the actual system, the ideal PR controller has the disadvantages of high parameter accuracy requirements, poor anti-disturbance ability, and difficulty in realization. The quasi-PR controller is applied to the single-phase photovoltaic inverter system, and considering factors such as the bandwidth limitation of the inverter and the accuracy of the detection system, the characteristic harmonic detection is used to selectively compensate the harmonics with large content and low order. The 3rd, 5th, and 7th harmonics, the steepest descent method with adaptive learning rate and additional momentum factor, improves the BP neural network, shortens the training time and overcomes the shortcomings of the BP neural network that is easy to obtain local optimal solutions. Inaccurate harmonic compensation, long system response time and other problems.

Description

technical field [0001] The invention belongs to the technical field of electrical control, and in particular relates to an adaptive harmonic elimination quasi-PR grid-connected inverter optimization control method. Background technique [0002] In recent years, a variety of distributed power sources in the power system are connected to the grid. While clean energy brings convenience, it also has negative aspects. The influence of harmonics has attracted more and more attention. The increase in harmonic content will have an impact on the power system, and even destroy the entire power network, resulting in inestimable losses. The distributed photovoltaic grid-connected system is easy to apply and popularize new energy power generation due to its excellent control performance, convenient operation and maintenance. become one of the research hotspots. The front stage of the commonly used two-stage single-phase photovoltaic grid-connected system can realize the maximum power tr...

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Problems solved by technology

[0003] Through a large number of database searches such as China National Knowledge Network, Web Of Science, Baidu Academic, Patent Network, etc., it is found that some patents or journals mainly solve the influence of single harmonics or apply existing algorithms to inverter controllers, such as the invention patent " Method for reducing output current harmonics of single-phase photovoltaic grid-connected inverter", publication number CN103560656A; utility model patent "A single-phase photovoltaic grid-connected inverter with harmonic suppression", authorization number CN205792212U; journal papers by Meng Jianhui, Photovoltaic grid-connected current optimization control based on PR control published by Shi Xinchun, Fu Chao, etc., Electric Power Automation Equipment, 2014,34(02): 42-47; Peng Yonglong, Zhang Kunfeng, Li Yabin published harmonic detection based on adaptive algorithm Method Research, Electrical Measurement and Instrumentation, 2018, 55(09): 6-9, etc. These patents or journal papers have single compensation methods, some compensation effects are not obvious, harmonic compensation is not accurate, and the system response time is too long and other defects

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