Quasi-PR grid-connected inverter optimization control method based on self-adaptive harmonic elimination

Abstract

The invention discloses a quasi-PR grid-connected inverter optimization control method based on self-adaptive harmonic elimination. For the shortcomings of high parameter precision requirement, poor anti-disturbance capability, difficult realization and the like of an ideal PR controller in an actual system, a quasi-PR controller is applied to a single-phase photovoltaic inverter system; in view of factors such as the bandwidth limit of an inverter, the precision of a detection system, and the like, characteristic harmonic detection is adopted for selectively compensating 3rd, 5th and 7th harmonics with relatively high content and relatively low orders; and a self-adaptive learning rate and a steepest descent method of additional momentum factors are adopted for improving a BP neural network, so that while the training time is shortened, the shortcoming that the BP neural network easily obtains a local optimum solution is overcome, and the problems of inaccurate harmonic compensation,overlong system response time and the like are solved.

Description

technical field [0001] The invention belongs to the technical field of electrical control, and in particular relates to an optimal control method for a quasi-PR grid-connected inverter with self-adaptive harmonic elimination. Background technique [0002] In recent years, a variety of distributed power sources in the power system are connected to the grid. Clean energy brings convenience but also has negative aspects. The impact of harmonics has attracted more and more attention. The increase of harmonic content will bring impact to the power system, and even destroy the entire power network, causing incalculable losses. Because of its excellent control performance, convenient operation and maintenance, the distributed photovoltaic grid-connected system is easy to apply and promote new energy power generation. become one of the hotspots of research. The front stage of the common two-stage single-phase photovoltaic grid-connected system can realize the maximum power tracking...

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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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