A unified control method for AC low-voltage ride-through and grid-connected to off-grid
A low-voltage ride-through and control method technology, applied in the direction of AC network voltage adjustment, AC network circuit, electrical components, etc., can solve the problem that MMC cannot be effectively differentiated, cannot be applied to various AC system faults, etc., and achieve fast grid-connected transfer. Off-grid switching to achieve the effect of continuous power supply
Active Publication Date: 2022-06-03
BEIJING SIFANG JIBAO AUTOMATION +1
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Problems solved by technology
[0005] The existing MMC low-voltage response schemes generally distinguish between non-opening faults and open-circuit faults, that is, when low voltage occurs, MMC cannot effectively distinguish, and can only perform one of the response methods of fault ride-through or grid-connected to off-grid. Not suitable for various AC system failure situations
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[0023] The invention proposes a unified control method of AC voltage fault ride-through and grid-connected to off-grid suitable for modular multi-level converter MMC for distribution network, so as to improve the operation of modular multi-level converter MMC in the AC power grid. The support capacity when the side fails, the AC grid side is figure 1 The area between the AC incoming side of the AC circuit breaker and the AC grid. The unified control method of AC voltage fault ride-through and grid-connected-to-off-grid includes switching and coping strategies of the MMC operation mode at the moment when the AC grid side fault occurs and when the fault is eliminated.
[0024] The present invention will be further described below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.
[0025] figure 1 Involving the MMC system topology diagram, the three-phase feeder of the AC grid is connected to the incoming end o...
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A unified control method for AC low-voltage fault ride-through and grid-connected to off-grid, which is suitable for modular multilevel converters used in distribution networks. When the inverter detects that the AC voltage provided to the AC load drops during grid-connected operation, it is determined that the AC grid has failed, and the rated active power of the converter is injected into the AC system to support the recovery of the AC grid; when the AC voltage is detected, The converter switches to the AC droop control mode, and if the relay protection action command is received, the converter maintains the AC droop control mode operation; if the relay protection action command is not received, the converter switches to the normal grid-connected operation mode . The invention has the functions of low-voltage ride-through and grid-connected to off-grid transfer, and can uniformly process non-open circuit faults and open circuit faults of the AC power grid. The converter can provide effective power support for temporary non-interruption faults to help the system recover quickly, and can perform fast grid-connected and off-grid switching for open-circuit faults to achieve continuous power supply for loads.
Description
technical field [0001] The invention relates to a reliable power supply method in the field of medium-voltage direct current power distribution, in particular to a unified control method for AC low-voltage fault ride-through and grid-connected-to-off-grid conversion suitable for modular multi-level converters used in distribution networks. Background technique [0002] The modular multilevel converter (MMC) is the basic equipment that constitutes the DC distribution network. Different from the application in the flexible DC transmission, the MMC needs to have grid-connected operation and off-grid operation in the application of the distribution network. At the same time, in order to meet the needs of high-reliability power supply and power flow transfer, MMC needs to have the ability to effectively respond to AC system failures. [0003] During grid-connected operation, the AC side and DC side of the MMC converter are connected to the AC grid and the DC grid respectively, an...
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IPC IPC(8): H02J3/00H02J3/16
CPCH02J3/00125H02J3/16Y02E40/30
Inventor 王一马彦宾王继慷李思刘树操丰梅梅红明王皆庆游涛王立超
Owner BEIJING SIFANG JIBAO AUTOMATION