Working method of grid-connected photovoltaic power generation system

Abstract

The invention relates to a grid-connected photovoltaic power generation system which consists of a phase-locked loop, a current transformator, a repetitive controller and a PWM generator. The invention also relates to a working method of the grid-connected photovoltaic power generation system, comprising the steps of: (1) acquiring network voltage phase position and grid-connected current; (2) designing the repetitive controller; (3) setting the modulation ratio, switch frequency and sampling times within unit cycle of an inverter; and (4) sending the output of the repetitive controller into the PWM generator, completing the switch operation for the inverter, and finally finishing grid-connected control for solar photovoltaic power generation. The invention has the advantages that the output waveform is greatly improved, the grid-connected current harmonic content is low, the total harmonic distortion is less than 1%, dc component is not contained, the power factor of the inverter is high, all indexes such as electrical energy quality and the like is in accordance with the requirement of grid-connected engineering technology, and the invention has application prospect.

Description

(1) Technical field [0001] The invention is used in the grid-connected photovoltaic power generation industry of solar energy, belongs to the interdisciplinary field of power electronics technology and control theory, and is particularly a working method of a grid-connected photovoltaic power generation system. (2) Background technology [0002] As the world's energy shortage and environmental pollution intensify, the utilization of renewable resources has attracted much attention. Solar energy has become the focus of people's utilization because of its universality, abundance and cleanliness. Today, solar energy is completing the transition from supplementary energy to alternative energy. At present, there are two main forms of solar energy utilization: thermal utilization and photovoltaic power generation utilization. Among them, photovoltaic grid-connection, which belongs to power generation utilization, is the development trend of solar energy utilization. [0003] Th...

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Problems solved by technology

However, the sliding mode control has the disadvantages that the ideal sliding mode switching surface is difficult to select, and the control effect is affected by the sampling frequency. It also has high-frequency jitter phenomenon, and the design needs to know the system uncertainty parameters and the limit of disturbance. The jitter makes the system unable to be accurate. Positioning, etc.

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