Anti-sagging control method for photovoltaic inverter in microgrid

Abstract

The invention relates to the technical field of photovoltaic power generation and aims at providing an anti-sagging control method for a photovoltaic inverter in a microgrid. The method comprises the following steps: realizing the whole anti-sagging control process through a photovoltaic inverter anti-sagging controller; calculating the frequency and the voltage of an alternating current bus of the microgrid by an anti-sagging control module to obtain an active power instruction and an inactive power instruction; sampling and fitting the output direct-current current value of a photovoltaic battery and the capacitance and voltage values of a direct current bus by a photovoltaic power-voltage curve fitting module to obtain a photovoltaic power-voltage curve; carrying out closed-loop control by the anti-sagging control module, and controlling the inverter by a current inner ring controller and a space vector pulse width modulation circuit through the proportion and integral action of a voltage / inactive closed-loop control module. The anti-sagging control method adopts a uniform control structure and can work in the grid connection and islanding two states of the microgrid. The schedulability of the photovoltaic power generation unit is enhanced in the grid connection state. The photovoltaic power generation unit can run in a maximum power point tracking mode in the islanding state.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation in a microgrid, in particular to an anti-droop control method of a photovoltaic inverter. Background technique [0002] In recent years, as the world's environmental problems and the depletion of non-renewable energy have become more and more serious, new energy has developed rapidly as a clean and renewable energy, especially photovoltaic power generation. As a way to effectively integrate and efficiently utilize new energy generation units, microgrid has attracted the attention of governments around the world. In the past, photovoltaics generally operated in the maximum power point tracking (MPPT) mode. In this mode, the output power of photovoltaics was greatly affected by environmental factors such as light and temperature. The dispatchability of photovoltaic power generation units was poor, and in microgrids with small capacity It causes great fluctuations in the voltag...

AI Technical Summary

Problems solved by technology

In the past, photovoltaics generally operated in the maximum power point tracking (MPPT) mode. In this mode, the output power of photovoltaics was greatly affected by environmental factors such as light and temperature. The dispatchability of photovoltaic power generation units was poor, and in microgrids with small capacity Causes great fluctuations in the voltage and frequency of the microgrid, affecting the power quality of the microgrid

In addition, in the micro-grid system, the types of micro-power sources are complex and the load changes greatly. Only energy storage is used to maintain the frequency and voltage of the micro-grid through droop control. Charging and discharging, the life is reduced, and the cost is increased

In recent years, photovoltaic constant power technology has been paid attention to. The document "Power control strategy for photovoltaic system based on the newton quadratic interpolation" provides a photovoltaic constant power control technology based on Newton's quadratic interpolation; and on this technology, the document "A New Frequency Regulation Strategy for Photovoltaic Systems Without Energy Storage" provides a method for photovoltaic power generation to support the grid frequency, but this method does not solve the active power reference command P o The selection problem, not to mention the ability of photovoltaics to output reactive power to adjust the voltage of the microgrid

These obviously do not fully tap the potential of photovoltaic power generation, which is not conducive to the efficient use and further development of photovoltaic power generation

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