Droop control method with network adaptive capacity in microgrid island mode

Abstract

The invention relates to the technical field of control of a multi-inverter parallel system in a microgrid island mode, in particular to a droop control method with network adaptive capacity in the microgrid island mode. A microgrid comprises N distributed direct-current power supplies DGs, three-phase inverters, LC filter circuits and an alternating-current bus, the number of the three-phase inverters is the same as that of the distributed direct-current power supplies DGs, the number of the LC filter circuits is the same as that of the distributed direct-current power supplies DGs, and Direct current of each distributed direct-current power supply DG is converted into alternating current through one three-phase inverter, then high-order burrs are filtered through the corresponding LC filter circuit, and then connection with the same alternating-current bus is achieved. The filter inductance in the ith filter circuit is Li, the filter capacitors Ci and N in each filter circuit are natural numbers, i is a natural number greater than or equal to 1 and less than or equal to N, Zi is equivalent impedance in a line where the ith distributed direct-current power supply DG is connected to the alternating-current bus, and the alternating-current bus is connected with a load.

Description

technical field [0001] The invention relates to the technical field of control of a multi-inverter parallel system in a micro-grid island mode, in particular to an improved droop control method capable of realizing power equalization and an adjustable droop coefficient. Background technique [0002] Microgrid has two modes of operation: grid-connected and islanded. Especially in islanded operation, distributed power generation undertakes the task of regulating power quality. The stable operation of microgrid is closely related to its control technology. At present, there are mainly the following methods: one is the virtual resistance optimization algorithm, which aims to minimize the power loss and suppress the circulating current between the converters. Keep the bus voltage at the rated value. The second is to add the line impedance identification link, which can accurately obtain the line parameters, and add the reactive power compensation link on the basis of the identif...

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Problems solved by technology

[0003] The technical problem to be solved by the present invention is: how to solve the problem that when the microgrid operates in the island mode, the distributed power supply usually adopts droop control to realize the distribution of multiple types of loads. Due to the inherent limitations of traditional droop, when the line impedance is inconsistent, there will be The problem of uneven power distribution and circulation makes it difficult to exert the efficiency of distributed power supply, and even cause the problem of distributed power supply overload

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