A Calculation Method for Three-Phase Decoupled Power Flow of Island AC-DC Hybrid Microgrid Based on Sequence Components

Abstract

The invention discloses an island AC / DC parallel-series micro-grid three-phase decoupling tide calculation method based on sequence components. The calculation method comprises the following steps that firstly, according to AC micro-grid operation characteristics, a Droop-type DG and AC / DC inverter steady state tide model is established; secondly, according to inverter grid-connected point voltage symmetrical characteristics, sequence component transformation is carried out on three-phase and single-phase grid-connected models; thirdly, according to DC micro-grid operation characteristics, a network node injection power equation and a DG steady state tide model are established; fourthly, under a sequence component system, an AC / DC three-phase decoupling tide calculation iterative equation is finally obtained. According to the island alternating current and direct current parallel-series micro-grid three-phase decoupling tide calculation method based on sequence components, the phase sequence component transformation relation is accurate, and the Droop-type DG and the AC / DC inverter grid-connected point injection power asymmetric characteristic are preserved; the AC / DC inverter AC side frequency and DC side voltage coupling relation is established, and the power balance between AC / DC subnets is effectively achieved; a circuit sequence current compensation method is used for completely decoupling and solving AC subnet three sequences in parallel, and the tide extreme efficiency is greatly improved.

Description

technical field [0001] The invention relates to the technical field of power system operation analysis and control, in particular to a calculation method for a three-phase decoupling power flow of an island AC / DC hybrid microgrid based on sequence components. Background technique [0002] As a good solution for DG grid connection and AC-DC network connection, the AC-DC hybrid microgrid will become an important part of the future power distribution system. There are two operation modes of grid-connected and islanded AC-DC hybrid microgrids. In the grid-connected operation mode, it is similar to the existing mature active distribution network analysis; while in the island operation mode, due to the loss of connection with the main grid, the hybrid power distribution system needs to form an independent and autonomous island power supply system to meet Power requirements for some or all of the loads on the AC / DC subnet. In order to improve the operational reliability, the isla...

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Problems solved by technology

The advantage of using the phase component method is that the physical concept is clear, and it is easy to deal with three-phase asymmetric components. However, when the system scale is too large, there are problems such as low calculation efficiency; and the sequence component method can realize three-sequence decoupling for a three-phase symmetrical system. Significantly reduce the scale of problem solving, but for the isolated island AC-DC hybrid microgrid, the characteristics of three-phase asymmetry, Droop-type DG, different grid connection methods of DC network, and no balanced nodes make the traditional sequence component decoupling method unable to directly application

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