Control method for smooth handoff of micro grid operation mode based on DG ad-hoc network strategy

Abstract

The invention discloses a control method for smooth handoff of a micro grid operation mode based on a DG ad-hoc network strategy, which comprises the following steps: when the operation mode of the micro grid is changed from a grid-connected mode into an isolated island operation mode, according to the condition that whether a distributed power source DG can perform isolated island operation, the micro grid is split into a plurality of DG local ad-hoc networks capable of performing independent operation, and continue power supply to the important load or the local load is ensured through the DG local ad-hoc networks; after each DG local ad-hoc network is stabilized, outward search is performed and the power supply range is enlarged, so that DG dynamic ad-hoc networks are formed; after all the DG dynamic ad-hoc networks are stabilized, the DG dynamic ad-hoc networks which satisfy interconnection requirements are sequentially subjected to network interconnection for operation by taking the DG dynamic ad-hoc network including a micro grid main power source as the center; after power supply of a public power distribution network recovers, all the DG dynamic ad-hoc networks are grid-connected with the public power distribution network for operation. According to the control method, the DG local ad-hoc networks ensure the continue power supply to the important load of the micro grid; the power supply is recovered to power-losing areas continuously through the DG dynamic ad-hoc networks, favorable conditions are provided for the operation mode, which is changed from the isolated island operation mode into the grid-connection operation mode, of the micro grid, and the smooth hand-off of the micro grid operation mode is ensured.

Description

Technical field [0001] The invention relates to a smooth switching control method of a microgrid, in particular to a control method for smooth switching of a microgrid operation mode based on a DG self-organizing network strategy. It belongs to the technical field of power system transmission and distribution. Background technique [0002] The microgrid can be operated in parallel with the public distribution network or on an island. When it is connected to the grid, it is supported by the public distribution network and has good stability. However, when a fault occurs in the distribution network or the microgrid, the microgrid The grid will immediately disconnect from the public distribution network and enter unplanned island operation. At this time, if the DG output of the distributed power generation using new energy in the microgrid cannot meet the load requirements of the microgrid, the voltage and frequency of the microgrid will A fall occurs, and in severe cases, the dist...

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Problems solved by technology

[0005] 1. When the microgrid is running in an isolated island, the main power supply generally requires good stability and large capacity. Often only diesel generators or energy storage devices are selected instead of distributed power sources. However, when connected to the grid, diesel generators In the shutdown state, the energy storage device is often in the floating charge state, so it is rare that the main power supply can be changed from PQ control to V / F control during the actual microgrid switching from grid-connected to unplanned island

[0006] 2. This method does not consider the power shortage when grid-connected to an unplanned island. It only considers the situation that the island operation can achieve power balance or the shortage is not large after the switchover. If the power shortage of the island is large after the unplanned switchover, the main power supply Distributed power supply capacity is limited, unable to fill the power gap of the microgrid, smooth switching will not be achieved

This method also does not fully consider the impact of the power shortage during the unplanned switching process. If the power shortage of the island is large after the unplanned switching, the droop control method has higher requirements for the adjustable capacity of the distributed power supply. Smooth switching in the grid will be difficult to achieve

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