Control method of miniature photovoltaic inverter having three-phase unbalance management function

Abstract

The invention provides a control method of a miniature photovoltaic inverter having a three-phase unbalance management function. The control method comprises the steps of performing real-time detection to obtain an illumination intensity coefficient Phi of a microgrid photovoltaic panel and current/voltage values of a plurality of single-phase miniature photovoltaic inverters to which a three-phase power grid is connected, calculating three-phase unbalance degree Mu, determining a power allocation efficient Gamma of a photovoltaic cell module by simultaneously combining the coefficient Phi and the unbalance degree Mu and by employing a fuzzy proportional integral (PI) control algorithm, and building an output power allocation scheme of the cell module; and building an i

-i<q> instruction current solution model, subtracting load current from the solved fundamental positive-sequence component to obtain a compensation current containing harmonic, a fundamental wave negative-sequence current and a fundamental wave active power transmission current in the compensation current, and finally, adjusting the size of an injected power to a microgrid from the battery module according to the allocation coefficient Gamma. The illumination intensity coefficient, the three-phase current unbalance degree, the fuzzy PI control algorithm and the i

-i<q> model are combined, and harmonic current suppression, load reactive power compensation and three-phase unbalance management are adaptively achieved.

Description

technical field [0001] The invention relates to a control method for a miniature photovoltaic inverter with the function of three-phase unbalance control. Background technique [0002] In the rural power grid, the three-phase unbalance problem of its power distribution network has been plagued by power supply units. Most of the medium and low-voltage power grids are stepped down by 10 / 0.4kV transformers, and then supply power to users in a three-phase four-wire system. [0003] Due to the uncontrollable capacity increase of single-phase users, the access of high-power single-phase loads, and the different timing of single-phase load power consumption, etc., problems such as harmonic current, load reactive power, and three-phase imbalance have been caused. If the low-voltage power grid operates under the condition of large three-phase load imbalance, it will have adverse effects on the low-voltage power grid and electrical equipment. [0004] Due to the rapid development of...

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Problems solved by technology

This structure has many disadvantages, including: large power loss, unstable power generation performance, etc.

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