Perturbation and observation method MPPT control method and system with photovoltaic array self-adaptive step size

Abstract

The invention relates to a perturbation and observation method MPPT control method with a photovoltaic array self-adaptive step size. The control method includes the main steps that output voltage and currents of a photovoltaic array PV are sampled to obtain a P-U characteristic curve, PV end voltage corresponding to incomplete differential and PV end voltage corresponding to ideal differential are Ua and Ub respectively, and the PV end voltage is divided into an interval I (0-Ua), an interval II (Ua-Ub) and an interval III (>Ub). Forward disturbance is performed in the interval I with the step size of d1, reverse disturbance is performed in the interval II with the step size of (2 eta-1), and reverse disturbance is performed in the interval III with the step size of d1. Signal samples of a voltage sensor and a current sensor of a system are connected into a micro processor, all processing modules for executing the method are stored in a program storage unit, a pulse width modulation module (PWM) is connected into output of the micro processor, and the PWM outputs a drive signal to control a direct-current conversion circuit of the photovoltaic array to achieve maximum power point tracing. Tracing is carried out with the small step size close to the MPP and with the large step size in far intervals, the step size is adjusted in a self-adaptive mode, the antijamming capability is improved, PV power loss is effectively reduced, and the energy use ratio is effectively increased.

Description

technical field [0001] The invention relates to the technical field of photovoltaic array system control, in particular to a photovoltaic array adaptive step-size perturbation observation method MPPT (Maximum Power Point Tracking) control method and system, by introducing an incomplete differential disturbance observation method and adaptively adjusting the step size to achieve effective The control tracks the maximum power point. Background technique [0002] Photovoltaic power generation industry is developing rapidly as a strategic industry to solve the increasingly prominent energy and environmental problems of mankind. However, the photoelectric conversion efficiency of the current photovoltaic array is low, only about 18%, and its output power is unstable, which hinders the development of the photovoltaic industry. [0003] The current-voltage (I-U) characteristics of photovoltaic cell arrays are affected by light intensity S, cell temperature T and load R, and have s...

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Problems solved by technology

[0017] The purpose of the present invention is to design a photovoltaic array self-adaptive step size disturbance observation method MPPT control method, for the traditional fixed step size of the photovoltaic array system to the voltage and current differential value in the step size judgment function of the disturbance observation method, which is susceptible to measurement interference, The impact of environmental changes leads to misjudgment of the disturbance step size near the maximum power point, and the problem of tracking speed and tracking accuracy cannot be taken into account. The incomplete differential is introduced instead of the ideal differential, and the corresponding incomplete differential is replaced by the ideal differential to avoid the disturbance step. Misjudgment, through adaptive variable step adjustment, the effective tracking of the maximum power point of the photovoltaic array is realized, the calculation is simple, and it is easy to implement in engineering

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