A control method for hybrid frequency regulation system of flywheel energy storage and doubly-fed variable-speed pumped storage

Abstract

The invention proposes a hybrid frequency modulation system and control method of flywheel energy storage and double-fed variable-speed pumped storage. The system includes a doubly-fed variable-speed pumped water storage unit and a flywheel energy storage unit connected in parallel to the power grid. The control method is as follows: when the frequency of the power grid is normal, the flywheel energy storage adopts speed control to keep its charge at 1 / 2, the doubly-fed induction motor takes the speed as the control target, and controls the pump and turbine to always run at the speed of optimal efficiency; the power grid In the early stage of frequency change, the flywheel energy storage adopts virtual inertia control and participates in inertial response; in the later stage of grid frequency change, the flywheel energy storage and double-fed variable-speed pumped storage participate in primary frequency regulation, and the flywheel energy storage maintains virtual inertia control, and the virtual inertia coefficient depends on The state of charge of the flywheel; the double-fed induction motor adopts droop control, and the droop coefficient depends on the actual deviation of the grid frequency and the speed of the double-fed induction motor, and the pump turbine controls the grid frequency deviation.

Description

technical field [0001] The invention relates to the application field of hybrid energy storage in power grid frequency regulation, in particular to a hybrid frequency regulation system and control method of flywheel energy storage and double-fed variable-speed pumped storage. Background technique [0002] With the continuous increase of the installed capacity of distributed energy such as wind power and solar energy, the intermittency and volatility of its output have brought great challenges to the safe and stable operation of the power grid. These distributed energy sources are generally connected to the grid through power electronic converters, which lack the damping and inertia of traditional generators when connected to the grid, which limits the penetration rate of new energy in the grid. In order to solve the above problems, it is necessary to configure energy storage with a certain capacity in the grid, participate in the frequency regulation of the grid, provide pow...

AI Technical Summary

Problems solved by technology

[0006] Since the stored energy of the flywheel is directly proportional to the square of the rotating speed, in order to further increase the stored energy, the rotating speed of the flywheel needs to be increased, which will cause problems such as heat generation and the increase of the withstand voltage level, which brings extreme problems to the traditional three-phase permanent magnet synchronous motor. big challenge

Images