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LCC-MMC (line commutated converter based high voltage direct current) system single-valve group switching in control method and direct-current transmission system

A control method and DC current technology, applied in the direction of power transmission AC network, etc., can solve the problem of single valve group online input, etc., and achieve the effect of high reactive power demand, good harmonic characteristics, and good application value

Active Publication Date: 2018-08-21
XUJI GRP +4
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The object of the present invention is to provide a single valve group input control method and a direct current transmission system of the LCC-MMC system, which are used to solve the problem of online input of the single valve group of the LCC-MMC hybrid direct current transmission system

Method used

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  • LCC-MMC (line commutated converter based high voltage direct current) system single-valve group switching in control method and direct-current transmission system
  • LCC-MMC (line commutated converter based high voltage direct current) system single-valve group switching in control method and direct-current transmission system

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Embodiment Construction

[0024] The specific embodiment of the present invention will be further described below in conjunction with accompanying drawing:

[0025] An LCC-MMC hybrid direct current transmission system, including a sending-end power grid, a sending-end converter station, a receiving-end converter station, a receiving-end power grid and a controller, the AC side of the sending-end converter station is connected to the sending-end power grid, The AC side of the end converter station is connected to the receiving end grid, the sending end converter station includes at least two LCC valve groups, the receiving end converter station includes at least two MMC valve groups, and the sending end converter station includes at least two LCC valve group, the DC side of each LCC valve group is cascaded connected, and each LCC valve group is equipped with a second DC field switch that controls the corresponding valve group to be turned on or off, and the DC side positive port of each LCC valve group i...

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Abstract

The invention provides an LCC-MMC (line commutated converter based high voltage direct current) system single-valve group switching in control method and a direct-current transmission system. According to the control method and direct-current transmission system, MMC valve groups are switched in, and then LCC valve groups are switched in, and finally, the time sequence setting of the direct-current voltage boosting of the valve groups is carried out, and therefore, the orderly online switching in of single valve groups of a high- and low-voltage valve group series type LCC-MMC system can be realized, the normal operation of other valve groups is not affected, and therefore, the method has a high application value. If the LCC is switched to the direct-current system at first, the LCC needsto operate under a state near a zero direct-current voltage for a long time during the charging starting process of the MMC, and at this moment, the triggering angle of the LCC is close to 90 degrees,an alternating-current system has large harmonics, requirements for the reactive power support of the system are high, and as a result, such condition is adverse to the operational stability of the system, and therefore, the MMC is switched to the direct-current system at first; and the MMC has a good harmonic characteristic and no reactive support requirements, even if the MMC operates under a zero direct-current voltage state for a long time, the MMC will not affect the stability of the alternating-current system.

Description

technical field [0001] The invention belongs to the technical field of DC power transmission in electric power systems, and in particular relates to a control method for inputting a single valve group in an LCC-MMC system and a DC power transmission system. Background technique [0002] Hybrid HVDC transmission system combines the mature technology of traditional HVDC (LCC-HVDC), high transmission capacity, low cost, flexible control of VSC-HVDC, independent decoupling of active and reactive power, and no commutation failure. current research hotspots. Among them, the modular multi-level converter MMC is a structure adopted in the flexible direct current transmission technology. The modular multi-level converter MMC adopts sub-module cascading technology, which has strong expansion performance, low harmonic level, With the advantages of small switching loss, it is more suitable to match the high-voltage and large-capacity characteristics of LCC to form a hybrid DC transmiss...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/36
CPCH02J3/36Y02E60/60
Inventor 杨美娟王先为吴金龙马焕张浩刘永慧姚为正
Owner XUJI GRP
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