Rapid voltage adjusting method of microgrid in off-network state

Abstract

The invention provides a novel voltage adjusting method of a microgrid in an off-network state and belongs to the technical field of voltage control. The method is characterized by, by utilizing a certain reactive power output by surplus capacity of other distributed power supplies, changing reactive power balance of the microgrid to enable the internal voltage of the microgrid to be stable at a new working point; when the internal voltage of the microgrid needs to be adjusted, comparing the voltage with the actually-collected internal voltage of the microgrid according to a voltage instruction to obtain a voltage difference through a certain calculation; sending the voltage difference to a PI adjuster, and obtaining a reactive power instruction through the PI adjuster; and then, adjusting the reactive power output by the distributed power supplies according to the reactive power instruction to enable the reactive power balance in the microgrid to change, so that the voltage working point moves on a voltage- reactive power sag curve, and the internal voltage of the microgrid changes. The method can realize rapid voltage adjustment, improves the quality of the supplied power or realizes voltage synchronization of grid connection of a microgrid system.

Description

technical field [0001] The invention relates to the technical field of voltage regulation, in particular to a method for fast voltage regulation of a microgrid under off-grid conditions. Background technique [0002] Microgrid refers to a small-scale power generation and distribution system composed of distributed power sources, energy storage devices, loads and other devices according to certain operating rules. It has two operating modes: networked and off-grid. Due to the advantages of microgrid in power supply reliability, security, and sustainability, it has attracted more and more attention. In the off-grid operation state of the microgrid, since there is no support from the external grid, the internal distributed power supply is required to establish voltage and maintain stability. Normally, the energy storage converter inside the microgrid works in the voltage source mode of droop control, relying on the droop characteristic curve, and automatically stabilizes the v...

AI Technical Summary

Problems solved by technology

Since the translation droop curve belongs to the secondary adjustment, it needs the participation of the upper monitoring system, and changes the original output characteristics of the energy storage converter, so the adjustment speed is relatively slow, and it is not suitable for frequent execution

Therefore, when it is necessary to adjust the internal voltage of the microgrid for reasons of power quality or when it is necessary to reconnect to the grid-connected state, the response of this method is slow, the adjustment time is long, and oscillation may occur in some cases. When the system is stable There may be a voltage deviation

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