Pendulum type MPPT (Maximum Power Point Tracking) algorithm of single-stage photovoltaic grid-connected inverter

Abstract

The invention discloses a pendulum type MPPT (Maximum Power Point Tracking) algorithm of a single-stage photovoltaic grid-connected inverter. 0.8 times of open-circuit voltage is used as command voltage for system start-up, so the voltage close to the maximum power point (MPP) output voltage can be achieved quickly, and the tracking speed of the maximum power point is improved. A novel variable step size perturbation and observation method is adopted close to the maximum power point, and the main idea of the algorithm is that the characteristic of voltage difference change before and after the voltage is analyzed on the two sides of MPP; since the given voltage of the MPPT algorithm is a group of step waves, the step length of the maximum power point tracking is changed through the characteristic of difference change of a current voltage moment and a previous moment. The algorithm has a simple structure, is easy to implement, hardly has any oscillation close to the maximum power point and is low in energy loss. The algorithm has broad application prospect in the fields such as new energy power generation.

Description

technical field [0001] The invention relates to photovoltaic grid-connected maximum power tracking control, in particular to a pendulum-type MPPT algorithm of a single-stage photovoltaic grid-connected inverter, and belongs to the field of power electronic photovoltaic grid-connected power generation control. Background technique [0002] The single-stage photovoltaic grid-connected system overcomes the low efficiency and high power consumption of the traditional two-stage photovoltaic grid-connected inverter system. The single-stage photovoltaic grid-connected system is mainly composed of photovoltaic cell array, DC bus capacitor Cpv, DA / AC converter, output filter and power grid. Its working principle is: photovoltaic cell modules are connected in series and parallel to increase the voltage on the DC side to ensure the normal operation of the inverter. At the same time, by controlling the DC / AC converter, the grid-connected current and the grid voltage have the same frequ...

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Problems solved by technology

[0004] The purpose of the present invention is to solve the complex implementation of the maximum power tracking control method of the known single-stage photovoltaic grid-connected inverter, which cannot simply and effectively solve the problem of oscillation near both sides of the maximum power point, and proposes a simple and reliable implementation of single-stage Pendulum MPPT Algorithm for Grid-connected Photovoltaic Inverters

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