Two-stage three-level three-phase four-wire system energy storage converter neutral-point potential balancing method and system

A three-phase four-wire system, potential balance technology, applied in the field of energy storage, can solve the problems of limited ability to suppress midpoint potential oscillation, increase switching loss, increase device voltage stress, etc., to achieve long-term stable operation, improve The effect of running stability and improving balance ability

Active Publication Date: 2021-06-04
CSR ZHUZHOU ELECTRIC LOCOMOTIVE RES INST
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AI Technical Summary

Problems solved by technology

[0004] Among them, the unbalanced component of the midpoint potential of the three-level inverter circuit includes a DC component and an AC component, which will cause many problems: 1) cause output voltage waveform distortion, and increase the content of low-order harmonics; 2) increase the voltage stress of the device, It is easy to cause overvoltage damage to the device
In the above method, the introduction of "transition vector" and the decomposition of zero level lead to an increase in the number of switches participating in the neutral point potential balance phase in a control cycle, which increases the switching loss, and for the case of a large load imbalance, the medium Limited ability to suppress point potential oscillations

Method used

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  • Two-stage three-level three-phase four-wire system energy storage converter neutral-point potential balancing method and system
  • Two-stage three-level three-phase four-wire system energy storage converter neutral-point potential balancing method and system
  • Two-stage three-level three-phase four-wire system energy storage converter neutral-point potential balancing method and system

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Embodiment Construction

[0052] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0053] like figure 1 As shown, the two-stage three-level three-phase four-wire energy storage converter midpoint potential balance method in this embodiment includes steps:

[0054] According to the low-voltage side inductor current reference value i in the three-level Buck / Boost circuit in the energy storage converter Lref , to control the three-level Buck / Boost circuit to work in Boost mode or Buck mode;

[0055] Reference Δu according to the midpoint potential ref The difference from the midpoint potential offset Δu adjusts the duty cycle of each switch in the Buck / Boost circuit in Boost mode or Buck mode, so that the total voltage of the DC bus is constant and the midpoint potential is balanced.

[0056] The present invention is aimed at the two-stage three-level three-phase four-wire system energy storage converter, by controlling the w...

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Abstract

The invention discloses a neutral-point potential balancing method and system for a two-stage three-level three-phase four-wire system energy storage converter, and the method comprises the steps: controlling a three-level Buck / Boost circuit to work in a Boost mode or a Buck mode according to a low-voltage side inductive current reference value iLref in the three-level Buck / Boost circuit in the energy storage converter; according to the difference between the midpoint potential reference delta(uref) and the midpoint potential offset delta(u), adjusting the duty ratio of each switch tube in the Buck / Boost circuit in the Boost mode or the Buck mode is adjusted, so that the total voltage of the direct-current bus is constant and balanced with the midpoint potential. The method has the advantages of constant direct-current bus total voltage, neutral-point potential balance, improvement of the operation stability of the converter and the like.

Description

technical field [0001] The invention mainly relates to the technical field of energy storage, in particular to a two-stage three-level three-phase four-wire energy storage converter midpoint potential balancing method and system. Background technique [0002] Energy storage technology has broad application prospects in the fields of improving grid reliability, demand side management, and access to new energy sources. Energy storage connected to the power system can improve the security and stability of the power grid, alleviate the load peak-valley difference, improve power quality, and promote the application of renewable energy; it forms an independent micro-grid with distributed power, which can improve the stability of the micro-grid system. The electrochemical energy storage system mainly includes a battery management system (BMS) and a bidirectional energy conversion system (Power Conversion System, PCS). It mainly has the following functions: 1) Under grid-connected ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/00H02J3/32H02J3/26H02J3/24H02M7/487H02M7/5387
CPCH02J3/00H02J3/32H02J3/26H02J3/24H02M7/487H02M7/53875Y02E40/50
Inventor 高首聪臧晓笛刘璐庞家猛汤腾蛟李琦薛冬良万能
Owner CSR ZHUZHOU ELECTRIC LOCOMOTIVE RES INST
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