Distributed energy storage device based on controllable DC bus

Abstract

The invention discloses a distributed energy storage device based on a controllable DC bus. The energy storage device includes a controllable DC bus part and an inverter part. The controllable DC bus part is a chain circuit composed of a plurality of half-bridge circuits. It is composed of a buck / boost bidirectional voltage regulation circuit, and the inverter part is composed of a three-phase bridge converter. The chain-type circuit obtains the switching signal from the voltage loop through the cascading modulation of the carrier added to the voltage equalization algorithm. The buck / boost bidirectional voltage regulation circuit obtains the switching signal by dividing the voltage sampling value by the voltage given value through PWM modulation. The inverter circuit is composed of vector-based The grid-connected algorithm of the control is modulated by PWM to obtain the switch signal. The proposed DC bus structure combines the step-down advantages of the chain circuit and the boost advantages of the buck / boost circuit. It has the advantages of simple control method, stable DC bus voltage, reduced energy storage cost and internal resistance loss, and balanced output of each energy storage unit. , strong versatility and easy expansion, etc., adapt to the special operating environment of low-voltage and high-power distributed energy storage.

Description

technical field [0001] The invention relates to a distributed energy storage device, in particular to a distributed energy storage device based on a controllable DC bus, which belongs to the field of distributed energy storage applications. Background technique [0002] With the development of ultra-high voltage power transmission and energy Internet technology, the real-time supply of a large number of incoming electricity from outside the region and the continuous operation of new energy generating units have alleviated the huge power demand brought about by the rapid economic development of my country's eastern coastal areas and reduced the environmental protection of the atmosphere. Governance pressure. However, the transmission capacity of UHV lines is huge. Once abnormal fluctuations or emergencies occur, local power shortages will occur, and even large-scale system oscillations or disconnections will occur, resulting in serious economic losses and adverse social impact...

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is the high internal resistance loss and the difficulty of bidirectional voltage regulation in the energy storage device based on the chain-link converter under the low-voltage and high-power distributed energy storage operating environment, and the problems brought about by the above problems There are many problems such as strong heat dissipation requirements, low device efficiency, high total DC voltage constraints, and high energy storage costs.

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