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

Abstract

The invention discloses a multi-machine parallel virtual synchronization control system and method for a cascaded energy storage system. First, it is based on the three-phase voltage of each cascaded energy storage converter, the grid active power given command, and the current current situation of the thermal power unit. The active power is obtained by power calculation, which is superimposed with the active power change to obtain the total active power given value, and then the active / reactive current given value is calculated, and then the average modulation voltage of the power conversion unit and the balanced control voltage component are superimposed to obtain The total modulation voltage is finally calculated to obtain the pulse driving signal of each power device. The invention realizes the high-voltage direct-mounting and parallel connection of multiple cascade-type energy storage converters to the high-voltage and low-voltage sides of the thermal power plant and joint frequency modulation operation of the thermal power units. It has multi-machine parallel virtual synchronization friendly operation, large capacity, high efficiency and rapid response. It has the advantages of two-way regulation of charge and discharge, high degree of self-balancing control, high power quality, and convenient centralized dispatch and 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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