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Off-line control method for mixed direct current transmission system

A technology of direct current transmission system and control method, which is applied in the direction of power transmission AC network, etc., can solve the problems of uneconomical, equipment capital investment, etc., and achieve the effects of preventing overvoltage and overcurrent, saving investment costs, and quickly shutting down the system

Inactive Publication Date: 2014-12-10
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, there is little detailed analysis on the outage control of the LCC-MMC hybrid DC transmission system in the current research at home and abroad; some people have proposed the outage method of introducing additional circuit breakers and discharge resistors, but this method will cause additional capital investment in equipment ,Uneconomical

Method used

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  • Off-line control method for mixed direct current transmission system
  • Off-line control method for mixed direct current transmission system
  • Off-line control method for mixed direct current transmission system

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Embodiment Construction

[0057] In order to describe the present invention more specifically, the technical solutions and related principles of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0058] Such as figure 1 As shown, the hybrid HVDC system includes a rectifier and converter station connected to the AC grid at the sending end and an inverse converter station connected to the AC grid at the receiving end. dc1 , DC transmission line and DC isolating switch S dc2 Connected to the inverter station; the rectifier station contains the AC circuit breaker S ac1 , the converter transformer and the converter unit, and the converter unit passes through the converter transformer and the AC circuit breaker S in sequence ac1 It is connected to the AC power grid at the sending end; the inverter converter station contains an AC circuit breaker S ac2 , converter transformer, current limiting device and converter unit, and the ...

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Abstract

The invention discloses an off-line control method for a mixed direct current transmission system. The method includes (1) reducing direct current to the set value; (2) gradually adjusting a tap of a converter transformer to the largest transformation ratio position; (3) adjusting reactive power between an inversion converter station and a receiving end alternating current power grid to zero and reducing direct current voltage; (4) gradually reducing the direct current from the set value to zero and further increasing the triggering angle of a thyristor converter to 120 degrees; (5) locking the thyristor converter and an MMC and sequentially disconnecting a direct current isolation switch, an alternating current circuit breaker and a three-phase bypass switch; (6) quickly releasing capacitor voltage of sub modules in the MMC to Ucs and then automatically releasing the voltage to zero. The method can ensure the stable fast off-line process, and avoids overvoltage or overcurrent. In addition, in the MMC capacitor discharging link, the extra circuit breaker and discharging resistance are removed in a starting current limit resistance reutilization mode, and the investment cost is saved.

Description

technical field [0001] The invention belongs to the technical field of direct current transmission system control, and in particular relates to an outage control method of a hybrid direct current transmission system. Background technique [0002] The rectifier station adopts LCC (grid commutated converter), and the inverter station adopts hybrid MMC (modular multilevel converter) composed of HBSM (half-bridge sub-module) and FBSM (full-bridge sub-module). )’s LCC-MMC hybrid DC transmission system integrates the advantages of both LCC and MMC, which not only reduces the system cost and operating loss, can realize power supply to passive islands, but also effectively avoids the risk of inverter station commutation failure. With the self-clearing capability of DC faults, it is very suitable for the transmission requirements of long-distance and large-capacity overhead lines in my country. [0003] Outage is a key problem that any DC transmission technology needs to face. During ...

Claims

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Application Information

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IPC IPC(8): H02J3/36
CPCY02E60/60
Inventor 徐政许烽张哲任
Owner ZHEJIANG UNIV
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