Adaptive control method for parameters of multi-inverter system based on mode switching under weak network

Abstract

The invention discloses an adaptive control method for parameters of a multi-inverter system based on mode switching under a weak network. The invention provides an adaptive control method for parameters of a multi-inverter system based on mode switching under a weak network in allusion to problems that the stability of a multi-inverter system with a full current source mode under the weak networkis generally improved through reducing the gain of current regulators of the grid-connected inverters but that the dynamic performance is deteriorated at the same time. The method comprises the stepsof firstly switching part of the grid-connected inverters in the multi-inverter system into a voltage source grid-connected mode, and then adaptively improving the gain of the current regulators of the grid-connected inverters still operating in a current source mode. Compared with the multi-inverter system with the full current source mode, the adaptive control method not only ensures the stableoperation of the system, but also greatly improves the dynamic performance of the grid-connected inverters.

Description

technical field [0001] The invention relates to a control method for grid connection of a multi-inverter system, in particular to an adaptive control method for parameters of a multi-inverter system based on mode switching under a weak grid. Background technique [0002] With the rapid development of distributed power generation systems, grid-connected inverters are widely used. Due to the existence of long-distance transmission lines and a large number of transformer devices in remote distributed power generation systems, the grid presents a non-negligible equivalent impedance, which makes the grid present a weak grid characteristic. At this time, the multi-inverter system composed of multiple grid-connected inverters will form a dynamic interconnection system with the grid during grid-connected operation. The impedance of the grid will lead to a decrease in the grid-connected stability of the multi-inverter system, causing resonance in the output current of the grid-conne...

AI Technical Summary

Problems solved by technology

[0010] In order to overcome the limitations of the above-mentioned various technical solutions, the present invention aims at the multi-inverter system of the full current source mode under the weak grid, and usually improves the system stability by reducing the gain of the current regulator of the grid-connected inverter, but at the same time To worsen the problem of dynamic performance, an adaptive control method of multi-inverter system parameters based on mode switching under weak grid is proposed. First, the method switches part of the grid-connected inverters in the multi-inverter system as voltage sources and grid mode, and then adaptively increase the gain of the current regulator of the grid-connected inverter still running in the current source mode. Compared with the multi-inverter system in the full current source mode, it not only ensures the stable operation of the system, but also greatly improves the parallel Grid Inverter Dynamic Performance

Images