LCC and MMC coordination control strategy suitable for DC power distribution network

Abstract

The invention discloses an LCC and MMC coordination control strategy suitable for a DC power distribution network, the control strategy adopts a mode of parallel operation of the LCC and the MMC, the DC side of the LCC and the DC side of the MMC are connected to the same DC bus and supply power to the DC power distribution network at the same time, and when the transmission power is small and the power flows reversely, the LCC quits operation, and the MMC bears all the transmission power; when the transmission power is large, the LCC is put into operation and bears most of power, the MMC adopts constant direct current voltage control and constant reactive power control by combining the characteristics of the LCC and the MMC converter station, and the LCC adopts a control strategy of constant direct current or constant direct current power. According to the control strategy, the LCC is used for replacing the MMC to bear part of transmission power, the number and capacity of MMC devices in the direct-current power distribution network are reduced, the LCC and MMC parallel operation mode is adopted in the coordination control strategy for LCC and MMC steady-state operation in the direct-current power distribution network, the direct-current sides of the LCC and MMC are connected to the same direct-current bus, and meanwhile power is supplied to the direct-current power distribution network.

Description

technical field [0001] The invention relates to the technical field of DC power distribution, in particular to a coordinated control of LCC (LineCommutated Converter, grid commutation converter) and MMC (Modular Multilevel Converter, modular multilevel converter) suitable for DC power distribution network Strategy. Background technique [0002] In order to meet the grid connection of renewable energy and the power supply demand for DC loads, DC distribution network has received extensive attention and application. However, the inertia of the DC distribution network system is low, and the DC voltage is prone to fluctuations. At the same time, the switching of loads in the DC distribution network and the random fluctuations in the output of distributed power sources such as photovoltaics and wind power will have a greater impact on the DC voltage. Even endanger the safe operation of the DC distribution network. [0003] As the connecting hub of the AC-DC grid, the grid-conne...

AI Technical Summary

Problems solved by technology

[0004] The existing coordinated control strategies of LCC and MMC have been widely used in the field of hybrid direct current transmission, but these coordinated control strategies are based on the field of high-voltage direct current transmission, and are not suitable for application in direct current distribution networks with fast and frequent changes in power flow.

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