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A control method for improving cascaded hybrid DC commutation failure ride-through capability

A hybrid DC and commutation failure technology, applied in the direction of power transmission AC network, etc., can solve the problems that cascade hybrid DC cannot be applied and increase project investment

Active Publication Date: 2021-09-10
JIANGSU ELECTRIC POWER RES INST +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] However, the relevant measures in Document 1 require additional installation of fault current suppression devices, which increases engineering investment
The relevant measures in Document 2 cannot be applied to cascaded hybrid DC

Method used

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  • A control method for improving cascaded hybrid DC commutation failure ride-through capability
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  • A control method for improving cascaded hybrid DC commutation failure ride-through capability

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Embodiment Construction

[0026] The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments. The present invention can improve cascaded hybrid DC commutation failure ride-through capability through the proposed sub-module active support technology, and the specific process is as follows:

[0027] Step 1: Under the given operating mode, extract the relevant operating parameters of the system, including the DC voltage U dcN , the equivalent inductance L of the converter eq , smoothing reactor inductance L d ;Number of sub-modules per bridge arm in normal operation in ; and calculate the DC inductance L of the system dc :

[0028] L dc = L eq +2L d ;

[0029] where the parameter U dcN , equivalent inductance L eq Inductance value L of flat wave reactor d It is a fixed parameter of the system and can generally be given.

[0030] Step 2: Introduce the switching coefficient Kc of the converter, whose physical meaning is t...

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Abstract

The invention discloses a control method for improving cascaded hybrid direct current commutation failure ride-through capability. In a given operating mode, system operating parameters are extracted to calculate the direct current inductance of the system; a converter representing the input ratio of sub-modules is introduced switch coefficient, and set the threshold of the DC current rise rate to be half of the maximum rise rate of the fault current; when the detected DC current rise rate exceeds the threshold, change the switch coefficient of all MMCs to its maximum limit value, that is, put all All sub-modules of the MMC converter; when the DC current rise rate is detected to be 0, switch the switching coefficient of all MMCs to 1.0, that is, the number of sub-modules input by all MMCs is the number during normal operation; after 200ms~300ms fault ride-through After a period of time, the system resumes operation. The invention can be realized only by the structure of the VSC itself, and does not need to install an additional current limiting device, which greatly improves the economy; and considers the hybrid direct current system in which the LCC and the VSC are cascaded, so the application range is wider and the applicability is higher.

Description

technical field [0001] The invention relates to the technical field of hybrid direct current transmission, in particular to a control method for improving commutation failure ride-through capability of cascaded hybrid direct current. Background technique [0002] Hybrid DC transmission has become an important development direction of DC transmission technology in recent years because it combines the advantages of conventional DC (LCC-HVDC) and flexible DC (VSC-HVDC). Receiver cascaded hybrid DC power transmission (such as figure 1 ) rectifier station consists of two sets of 12-pulse LCCs in series, and the inverter station consists of a set of 12-pulse commutation converters (LCCs) and voltage source converters (VSCs) connected in series in parallel, and the low-end VSC is extended to Multiple VSCs are connected in parallel and placed on different regional power grids. While increasing the transmission power of the hybrid DC system, the multi-location structure is also cond...

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 赵静波徐珂周前江琴李保宏
Owner JIANGSU ELECTRIC POWER RES INST