Multi-alternating-current-port high-voltage direct-hanging energy storage power conversion system and control method thereof

Abstract

The invention discloses a multi-alternating-current-port high-voltage direct-hanging energy storage power conversion system and a control method thereof. The system comprises a cascaded H-bridge energy storage system which comprises a plurality of H-bridge direct-current sides connected with an energy storage battery in parallel and then cascaded; and a multi-alternating-current-port flexible interconnection module which is connected in series with the cascaded H-bridge energy storage system, and comprises a plurality of first single-phase converters and second single-phase converters connected in parallel and connected with the same common connection bus. According to the invention, interconnection of multiple alternating-current feeder lines and energy storage sharing are realized, charge and discharge control of CHBESS can be realized, and flexible interconnection of alternating-current power grids is realized while an energy storage function is realized; the active power control is realized by adopting a series voltage source mode without full power, so that the occupied area is small, the cost is low, the loss is small, and the response speed is high; and the multi-port flexible interconnection module has the characteristics of modularization and easy expansion, and expansion of the interconnection ports can be quickly and flexibly realized by increasing the number of the first single-phase converters connected in parallel in the interconnection module.

Description

technical field [0001] The invention relates to the technical fields of power grid energy storage power conversion technology, flexible interconnection of AC power grids, and power electronics, and in particular to a multi-AC port high-voltage direct-connected energy storage power conversion system and a control method thereof. Background technique [0002] In recent years, the demand for energy on the user side has grown rapidly, and the types of AC and DC loads have become increasingly diversified, resulting in the problem of unbalanced feeder loads. Although the traditional AC power grid has significant advantages in system stability and reliability, it cannot effectively solve the problem of feeder congestion due to insufficient control capabilities; the capacity of a single feeder caused by unbalanced loads reaches the upper limit, which limits the actual capacity of the entire distribution network system , so that it is far below the design capacity, seriously affectin...

AI Technical Summary

Problems solved by technology

The first solution is time-consuming, labor-intensive, and costly, which is not conducive to large-scale development; although the second solution can optimize the operation of the power grid to a certain extent, the adjustment accuracy of common on-load voltage regulators and feeder switch actions is insufficient, and the response Slow speed; Another solution with good development prospects is to provide interconnection ports of different AC feeders through flexible AC interconnection devices to realize flexible interconnection and active power control between feeders

This solution makes full use of the real-time and rapidity of power electronic device control to realize rapid power regulation between adjacent networks, thereby optimizing power flow distribution. Management and adjustment capabilities, as well as efficient source-network-load optimization capabilities can greatly improve power supply quality. The mainstream topology of existing flexible AC interconnection devices mainly uses back-to-back voltage source inverters, and multiple voltage source inverters share DC bus. Formation can realize multi-feeder power decoupling and control. However, this topology is composed of a full-power voltage source inverter, so it has disadvantages such as high cost, large loss, large volume, and high failure rate. In addition, the above method None of them can effectively solve the problems of insufficient power grid acceptance capacity and severe wind and solar abandonment. However, the energy storage system connected to the grid can store electric energy and improve the grid acceptance capacity, thereby reducing the phenomenon of wind and solar abandonment and improving energy utilization.

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