Active power-frequency coupling control method based on electromechanical transient model of doubly-fed variable-speed pumped storage unit under water pumping working condition

Abstract

The doubly-fed variable-speed pumped storage unit is a novel hydroelectric system, and due to the fact that the rotating speed is continuously adjustable under a water pumping working condition, on the premise that a static lift is guaranteed, the input power adjusting range of the unit is widened through variable-speed operation. For the potential that an excavator unit participates in power grid frequency modulation, the invention relates to an active power-frequency coupling control method based on an electromechanical transient model of a doubly-fed variable-speed pumped storage unit under a water pumping working condition. The method comprises the following steps of: firstly, establishing a simplified electromechanical transient model of a variable-speed unit under a water pumping working condition; according to the model, on the basis of the operation characteristics of a pump turbine with the reversible water pumping working condition, considering the dynamic characteristics of fluid in an overflowing pipeline, and considering the additional friction effect of guide vanes; revealing the essential reason of the frequency modulation capability of the water pumping working condition unit from the angle of hydraulic power; clarifying a mechanism of improving power grid frequency characteristics by a water pumping working condition unit, and giving recommendation range of controller parameters; and finally, through simulation and experiment results, verifying the capability of improving the frequency characteristic of the power grid of the water pumping working condition unit.

Description

technical field [0001] The invention relates to the field of pumped storage, in particular to electromechanical transient modeling and active power-frequency coupling characteristics of a doubly-fed variable-speed pumped-storage unit under pumping conditions. Background technique [0002] Pumped hydro storage is one of the most important tools to solve the frequency stability problems faced by the current grid. Due to the peak and valley characteristics of the power grid, pumped storage units usually operate in pumping conditions at night. Because the conventional pumped storage unit adopts a DC excitation synchronous motor, the speed is fixed (or divided into several gears), the input power cannot be continuously adjusted under this working condition, and it does not have the ability to participate in the frequency regulation of the power grid. [0003] The doubly-fed variable-speed pumped-storage unit uses an AC-excited asynchronous motor, and the back-to-back converter p...

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Problems solved by technology

[0004] However, although the use of VSPS under pumping conditions for power grid frequency control has been reported abroad, the mathematical description of the electromechanical transient model of the VSPS under pumping conditions and the research on the dynamic response characteristics of the unit are still very difficult in the long-term scale. Insufficient; the essential mechanism of VSPS improving the frequency characteristics of the power grid under the pumping condition is still unclear; furthermore, the applicability of the SFR (system frequency response) model of the power grid including the active power-frequency coupling of the VSPS under the pumping condition is still not clear when calculating the frequency response of the power system. not very clear

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