Energy routing system based on LCC-MMC, and direct current fault protection method

Abstract

The invention discloses an energy routing system based on LCC-MMC, and a direct current fault protection method, and belongs to the technical field of hybrid high-voltage direct current transmission. The topology of the system comprises a power grid phase control converter LCC, a modular multilevel converter MMC, an energy storage device BESS, an improved hybrid DC circuit breaker DCCB and a direct current bus. The energy regulation and control mode of the system comprises LCC side constant direct current voltage control, MMC alternating current side power decoupling control and energy storage interface Buck / Boost control. According to the direct current fault protection method of the system, energy storage unit power switching control and an improved hybrid direct current circuit breaker DCCB are combined to form a set of complete combined fault protection scheme. While the fault current is quickly isolated, the MMC side alternating current can be prevented from being distorted, the power supply quality of the system is greatly improved, reliable and stable operation of the alternating current power grid is ensured, and quick recovery of the system after the fault is facilitated.

Description

technical field [0001] The invention relates to the technical field of hybrid high-voltage direct current transmission systems, in particular to an energy routing system and a direct current fault protection method based on LCC-MMC, which are applicable to the field of medium and high voltage long-distance power transmission. Background technique [0002] In recent years, with the depletion of non-renewable energy stocks and the seriousness of environmental pollution, the single energy structure currently used may not be able to meet the future development needs of mankind. Therefore, in order to improve the power generation level of renewable energy and alleviate the In response to the energy crisis, scholars at home and abroad put forward the concept of Energy Internet. As the product of the deep integration of smart grid and renewable energy, the Energy Internet is a new energy network that solves the energy crisis and promotes the transformation of the energy structure. ...

AI Technical Summary

Problems solved by technology

High-voltage DC is of great significance for large-capacity and long-distance power transmission, promoting grid connection and consumption of new energy, and improving the stable operation of power systems. There are no fault characteristics such as natural zero-crossing point and fast current rise rate, so the problem of DC short-circuit fault has always been a key task to be solved in the field of high-voltage transmission

Although the DC circuit breaker can act in time to block the fault current when a fault occurs, it cannot maintain the stable operation of the AC side grid because the DC side cannot provide the power missing from the AC side

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