A multi-machine parallel virtual synchronization control system and method for cascaded energy storage system

Abstract

The invention discloses a multi-machine parallel virtual synchronization control system and method for a cascade energy storage system. According to the three-phase voltage of each cascaded energy storage converter, a grid active power given command, as well as the current power of the thermal power unit, the active power is calculated and obtained; the active power and the active power change aresuperposed to obtain the total active power given value, and then the average modulation voltage and the equalization control voltage components of the power conversion unit are superposed to obtainthe total modulation voltage. finally, the pulse driving signals of each power device are calculated. The invention realizes the high-voltage direct-hanging parallel connection of multiple cascaded energy storage converters to the joint frequency modulation operation of the low-voltage side of the high-power transformer and the thermal power unit of the thermal power plant, and has the advantagesof virtual synchronous friendly operation of multiple machines in parallel, high-capacity, high-efficiency and fast response, bi-directional charge-discharge regulation, highly self-balanced control,high power quality and convenient centralized dispatching frequency modulation.

Description

technical field [0001] The invention relates to a multi-machine parallel virtual synchronization control system and method of a cascaded energy storage system, which belongs to the technical field of energy storage system frequency modulation. Background technique [0002] At present, limited by the maximum withstand voltage and maximum current parameters of high-power power electronic switching devices such as IGBTs and silicon carbide devices, the power of a single power conversion system (PCS) is generally not greater than 500 kW, that is, 0.5 MW. It is not enough for energy storage converters of this power level to be used in fire-storage combined frequency modulation. At present, in engineering practice, multiple converters are generally operated in parallel on the low-voltage AC side, and then connected to the fire through multiple step-up transformers. The realization of the low-voltage side of the 6kV high-power transformer in the power plant not only adds a power f...

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Problems solved by technology

It is not enough for energy storage converters of this power level to be used in fire-storage combined frequency modulation. At present, in engineering practice, multiple converters are generally operated in parallel on the low-voltage AC side, and then connected to the fire through multiple step-up transformers. The realization of the low-voltage side of the 6kV high-power transformer in the power plant not only adds a power frequency transformer step-up link, which reduces system efficiency, but also due to the distributed parallel connection of multiple low-voltage units, the frequency modulation speed is limited by the multiple low-voltage parallel energy storage converters The communication coordination time is relatively slow, and the frequency modulation speed is generally about 100ms. In addition, the existing energy storage converters are mainly composed of power electronic devices, which do not have inertia and cannot make due contributions to maintaining the dynamic stability of the power grid.

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