Method for improving transient stability of system by combining crowbar circuit and energy storage device

Abstract

The invention relates to a method for improving the transient stability of a system by combining a crowbar circuit and an energy storage device. The method is applied to a multi-machine system with afan; and a rotor-side crowbar protection circuit is employed and a superconducting energy storage device is installed at the exit of a wind power plant. The method comprises: when the system works normally, the superconducting energy storage device works in a work mode of stabilizing output fluctuation of the fan; when a short-circuit fault occurs at the system, the voltage at the grid-connected point of the fan is reduced, the rotor current reaches a set value, the rotor-side crowbar protection circuit starts to work, and the work mode of stabilizing output fluctuation of the fan is changed into a work mode with a fault after the superconducting energy storage device detects a crowbar signal change; the superconducting energy storage device starts detecting a power angle difference signalbetween two synchronous machines of the two-machine systems; and when the absolute value of a difference between a power angle difference signal at a current time and a power angle difference signalat a previous time is larger than a set value epsilon, the superconducting energy storage device works continuously in the work mode with a fault.

Description

technical field [0001] The field of the present invention is the transient stability of power systems including wind farms, and relates to crowbar protection circuits and superconducting energy storage devices for double-fed wind turbines. In particular, it provides a combined rotor side crowbar protection circuit and superconducting energy storage devices. A method to improve the transient stability of the system. Background technique [0002] With its clean and non-polluting characteristics, wind power has become one of the most widely used new clean energy sources, and its proportion in the power grid continues to increase. With the increase of wind power penetration power in the system, low-voltage ride-through requirements are put forward for wind turbines, requiring the wind turbines to keep running without disconnecting from the grid when the voltage drops at the grid-connected point, and to provide a certain amount of reactive power support to the system as much as p...

AI Technical Summary

Problems solved by technology

Some literatures use the method of theoretical derivation to analyze the influence of fans on the transient stability of the system by means of the extended equal area criterion [6-9] , but in the analysis process, the mechanical power and electromagnetic power of the fan are processed in a manner similar to that of the synchronous machine, which is not applicable to the fan [10]

And the most important thing is that most of the research lacks a reasonable solution to improve the transient stability of the system.

Images