Flywheel energy storage and doubly-fed variable-speed pumped storage hybrid frequency modulation system and control method

Abstract

The invention provides a flywheel energy storage and doubly-fed variable-speed pumped storage hybrid frequency modulation system and a control method. The system comprises a double-fed variable-speed water pumping energy storage unit and a flywheel energy storage unit which are connected in parallel to a power grid. The control method comprises the steps that when the power grid frequency is normal, flywheel energy storage adopts rotating speed control, the charge capacity of flywheel energy storage is kept at 1 / 2, and the double-fed induction motor takes the rotating speed as a control target to control the pump turbine to always run at the rotating speed with the optimal efficiency; at the initial stage of power grid frequency change, flywheel energy storage adopts virtual inertia control and participates in inertia response; at the later stage of power grid frequency change, flywheel energy storage and doubly-fed variable-speed pumped storage participate in primary frequency modulation, flywheel energy storage keeps virtual inertia control, and a virtual inertia coefficient depends on the charge state of a flywheel; the doubly-fed induction motor adopts droop control, the droop coefficient depends on the actual deviation of the power grid frequency and the rotating speed of the doubly-fed induction motor, and the pump turbine controls the deviation of the power grid frequency.

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...

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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

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