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An AC fault ride-through control method for rectifier stations in hybrid DC transmission systems

A power transmission system, hybrid DC technology, applied in the direction of power transmission AC network, etc., can solve problems such as interruption, DC voltage drop of rectifier station, power transmission reduction, etc., to achieve automatic switching, improve power transmission capacity, and reduce power transmission interruption Probability of Occurrence Effect

Active Publication Date: 2020-03-31
ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, when the AC fault of the rectifier station occurs in the hybrid DC transmission system of this topology, the AC voltage drop will cause the DC voltage of the rectifier station to drop, but the DC voltage of the inverter station MMC converter station will not be affected
Due to the reduced voltage difference between the two stations, the power transmission will be reduced or even interrupted

Method used

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  • An AC fault ride-through control method for rectifier stations in hybrid DC transmission systems
  • An AC fault ride-through control method for rectifier stations in hybrid DC transmission systems
  • An AC fault ride-through control method for rectifier stations in hybrid DC transmission systems

Examples

Experimental program
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Effect test

Embodiment 1

[0042] Embodiment 1, the 100 Hz protection threshold of the direct current is 0.03-0.05 times the rated value of the direct current side current of the rectifier station. After entering the maximum modulation ratio control mode of the inverter station, when the 100Hz component of the positive and negative DC current of the inverter station recovers, that is, when it is less than the set DC current 100Hz protection threshold, the DC current 100Hz protection exits, and the inverter station returns to constant DC voltage control mode.

Embodiment 2

[0043] Embodiment 2, monitor the DC current change of the inverter station and the size of the 100 Hz component in the positive and negative DC currents in real time, judge whether to start the DC current 100 Hz protection, and enter the maximum modulation ratio control mode. The DC current 100Hz protection principle is shown in the following formula:

[0044]

[0045] Among them, I dc_P_100Hz is the 100Hz component of the extracted DC current; I dc_P_N and I dc_N_N is the positive and negative DC rated current, and the positive and negative DC rated current values ​​are the same, that is, the DC side current rating of the rectifier station; I dc_P , I dc_N is the actual DC current value on the positive and negative DC lines; k 1 and k 2 is the protection coefficient, both take 0.03, I setP 100Hz protection threshold for positive polarity DC current, I setN It is the 100Hz protection threshold of positive polarity DC current; the protection action delay is 10ms. Whe...

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Abstract

The invention relates to an alternating current fault ride-through control method of a rectifier station for a hybrid direct current power transmission system. An LCC (Line Commutated Converter) rectifier station uses constant direct current current control, minimum trigger angle control and low voltage current limit control. An MMC (Modular Multi-level Converter) inverter station selects constant direct current voltage control, and collocates with backup maximum modulation ratio control and constant current control. During normal operation, the rectifier station operates in a constant current control mode, and the inverter station operates in a constant direct current voltage control mode. When an alternating current side of the rectifier station fails, the operating mode of the rectifier station is converted into a minimum trigger angle control mode to compensate for the direct current voltage drop of the rectifier station, and the operating mode of the inverter station is converted into a maximum modulation ratio control mode to reduce the direct current voltage reference value of the inverter station. Moreover, enable signals of control modes of the rectifier station and the inverter station are acquired from the electric quantity of each station without relying on the communication between converter stations. The method provided by the invention can fully utilize the advantages of low cost of LCC and flexible control of MMC and the like, the transmission power of a direct current system can be improved to a larger extent, and the probability of power transmission interruption is reduced.

Description

Technical field [0001] The invention relates to a hybrid direct current transmission system of LCC and MMC, belonging to the technical field of high-voltage transmission. Background technique [0002] Traditional DC transmission technology based on grid commutated converter (LCC: Line Commutated Converter) has the advantages of mature technology, low cost, and strong overload energy, but it also has commutation failure, large harmonic content, and the need for reactive power compensation. Problem; Flexible DC transmission technology based on modular multi-level voltage source converter (MMC: Modular Multi-level Converter) can independently adjust active and reactive power, has superior controllability and flexibility, and is a solution to the problem at the receiving end. The power grid is weak and passive grid is an effective way to receive power. However, flexible DC technology has high cost, large losses and complicated control. The rectifier station of the hybrid DC tra...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/36
CPCH02J3/36Y02E60/60
Inventor 洪潮张野孙刚时伯年刘斌梅红明徐刚刘志超
Owner ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD
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