Photovoltaic MPPT control method based on linear iteration

Abstract

The invention discloses a photovoltaic MPPT control method based on linear iteration. The photovoltaic MPPT control method includes the following steps that (1) a point A with the voltage on a power-voltage characteristic curve being uL and a point B with the voltage on the power-voltage characteristic curve being uR are obtained, wherein the uL ranges from 0 to Um, uR ranges from Um to UOC, Um is the voltage of a point with maximum power, and UOC is an open-circuit voltage; (2) a point D with the voltage on the power-voltage characteristic curve being the same as that of a point C which is an intersection point of the tangent line of the point A and the tangent line of the point B is obtained to serve as a point with the approximately maximum power; (3) a tangent line passing through the point D is obtained, whether the absolute value |P'(uC)| of the slope of the tangent line is smaller than a predetermined accuracy threshold value epsilon is judged, if the absolute value |P'(uC)| of the slope of the tangent line is smaller than the predetermined accuracy threshold value epsilon, the step (5) is executed, otherwise the step (4) is executed; (4) if P'(uC) is larger than 0, the point D is used as a new point A, step (2) is executed, and if the P'(uC) is smaller than 0, the point D is used as a new point B, the step (2) is executed; (5), the point D is determined to be the point with the maximum power, and tracking of the point with the maximum power is achieved. According to the photovoltaic MPPT control method, higher tracking speed and higher tracking accuracy can be obtained at the same time, and the method is simple and easy to implement.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic power generation, and more specifically relates to a photovoltaic MPPT control method based on linear iteration. Background technique [0002] Photovoltaic cells are devices that convert light energy into electrical energy using the photovoltaic effect. Since the output power of photovoltaic cells is a nonlinear function of light intensity, temperature and load, in order to make full use of the energy of the photovoltaic array, the photovoltaic power generation system is equipped with a Maximum Power Point Tracking (MPPT) control circuit. [0003] Traditional photovoltaic maximum power point tracking methods include constant voltage method (CV), short-circuit current method, interpolation calculation method, perturbation and observation method (P&O), conductance incremental rate method (INC), variable step size algorithm, intelligent algorithm, etc. Although the constant voltage method and t...

AI Technical Summary

Problems solved by technology

The conductance increment method (INC) is an improved algorithm of the disturbance observation method, which has high precision, but still has the disadvantage of slow speed.

The variable step size algorithm can give a good balance between speed and accuracy, but its step size rule is not easy to determine

Intelligent algorithms such as fuzzy control and neural network control are more suitable for solving nonlinear problems in theory, but their control laws require a long training time and depend on the experience of operators, so it is difficult to implement in practice at present

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