Tracking control method for maximum power of photovoltaic power generation system

Abstract

The invention discloses a tracking control method for the maximum power of a photovoltaic power generation system. According to the method, a self-adaption variable step resistance incremental method is based, the dynamic performance and the steady-state performance of a photovoltaic system are integrated into account, and a photovoltaic cell output P-U characteristic curve is demarcated through a step transfer function introduced. According to photovoltaic cell parameters supplied by a photovoltaic cell manufacturer, two different fixed step sizes in fixed step zones on the left and right sides of a maximum power point are selected when the system is operated in a fixed step mode, the different fixed step sizes meet certain proportional relation, and a speed factor of the system in variable step size mode is selected. In the condition of intensive change of the external environment, compared with a fixed step resistance incremental method, the self-adaption variable step resistance incremental method can improve the response speed and the steady-state accuracy of the system; when simulating slow change condition of the external environment in natural conditions, the self-adaption variable step resistance incremental method has good dynamic performance and steady-state performance, so that the method effectively improves the tracking speed and the stability accuracy at the maximum power point.

Description

technical field [0001] The invention relates to the technical field of solar photovoltaic power generation, in particular to a maximum power tracking control method for a photovoltaic power generation system based on an adaptive variable step size resistance increment method. Background technique [0002] Solar energy, as a new type of green energy, can solve the energy crisis caused by the exhaustion of conventional energy sources, and has attracted widespread attention at home and abroad. Photovoltaic power generation is one of the main forms of utilizing solar energy at present. The output characteristics of photovoltaic cells have strong nonlinear characteristics. Its output power is not only related to the internal characteristics of photovoltaic cells, but also affected by external environmental conditions (light, temperature). Using maximum power point tracking technology (Maximum power point track, MPPT) can effectively Improve the energy conversion efficiency of ph...

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Problems solved by technology

AVariableStepSizeINCMPPTMethodforPVSystems (FangruiL, ShanxuD, FeiL, et al.AVariableStepSizeINCMPPTMethodforPVSystems.IEEETransactionsonIndustrialElectronics, 2008.55(7):p.2622-2628.) discussed a variable step size conductance incremental method, and gave a variable step size step size formula, but The tracking effect of this method is not very good in the case of drastic changes in external conditions, the working area of ​​variable step size is very small, the system has been working in the state of fixed step size, and the steady-state power loss is large; the system works in the state of variable step size, dynamic Tracking speed is slow, that is, there is a "dead zone" problem

ANovelImprovedVariableStep-SizeIncremental-ResistanceMPPTMethodforPVSystems (MeiQ, ShanM, LiuL, et al. ANovelImprovedVariableStep-SizeIncremental-ResistanceMPPTMethodforPVSystems.IEEETransactionsonIndustrialElectronics, 2011.58(6):p.2427-2434.) proposed a new conductance incremental step change method A step-size demarcation method and a step-size setting formula, but the step-size demarcation method has a large amount of calculation (multiple derivation operations are required), and the step-size demarcation formula fails to make full use of the demarcation function, which also increases the amount of calculation, giving The realization of this method brings some difficulties

[0005] In order to solve the contradiction between the tracking speed and steady-state performance caused by the commonly used disturbance observation method and conductance incremental method, the present invention proposes a photovoltaic power generation system based on the adaptive variable step resistance incremental method. The power tracking control method comprehensively considers the dynamic performance and steady-state performance of the photovoltaic system, and divides the output P-U characteristic curve of photovoltaic cells by introducing a step size conversion function

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