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Method for controlling flexible voltage of flexible direct current system

A flexible DC and DC voltage technology, applied in the direction of AC network voltage adjustment, AC network circuit, electrical components, etc., can solve problems such as high cost, achieve the effect of increasing life, multi-control and safety margin, and reducing the time of high voltage

Pending Publication Date: 2022-03-01
CHINA THREE GORGES PROJECTS DEV CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although systems such as cables and DC cables have reserved sufficient margins at the beginning of the design, large margins mean high costs

Method used

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  • Method for controlling flexible voltage of flexible direct current system
  • Method for controlling flexible voltage of flexible direct current system
  • Method for controlling flexible voltage of flexible direct current system

Examples

Experimental program
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Embodiment Construction

[0032] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0033] Set the rated DC voltage of the flexible DC project to U r , the RMS value of the rated valve side line voltage is U acr , modulation ratio m r :

[0034]

[0035] Generally, there are m r =0.85~0.9.

[0036] Full-voltage operation: the DC operating voltage of the flexible DC system is the rated voltage U r ;

[0037] Step-down operation: the DC operating voltage of the flexible DC system is k ud u r , k ud <1.

[0038] like figure 1 Shown is the overall flow chart of the present invention, when the DC transmission power is less than or equal to k p1 P r more than Δt 1 , the DC operating voltage is k ud u r ;

[0039] When the DC transmission power is greater than or equal to k p2 P r more than Δt 2 , the DC operating voltage is U r .

[0040] Change the DC voltage control command, and at the same time a...

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Abstract

The invention discloses a control method for flexible voltage control of a flexible direct-current system, which is characterized in that when the transmission power of the direct-current system is low, the direct-current voltage of a flexible direct-current power transmission system is properly reduced, so that the high-voltage bearing time of primary equipment is shortened, and the transient overvoltage tolerance of the equipment is reduced. When the transmission power of the DC system is large, the DC voltage of the flexible DC power transmission system is rapidly recovered to a rated value, and full-power operation of the system is ensured. According to the control method, power judgment and power prediction judgment are combined, and the problem of frequent system operation voltage switching caused by power fluctuation can be solved.

Description

technical field [0001] The invention relates to a flexible direct current transmission system of a power system, in particular to a flexible voltage control method of a flexible direct current system. Background technique [0002] Large-scale long-distance new energy access systems generally use flexible DC systems to access AC power grids. However, new energy systems, especially wind energy, have large changes in wind resources with seasons and cycles. In strong wind seasons, the soft straight system delivers higher power, and in weak fan seasons, it will operate in low power delivery mode for a longer period of time. At this time, the DC system delivers a small current at the rated voltage. DC cables operate under high DC voltage all the year round. Although systems such as cables and DC cables have reserved sufficient margins at the beginning of the design, large margins mean high costs. In order to prolong the service life of DC cables and reduce the transient voltag...

Claims

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Application Information

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IPC IPC(8): H02J3/36H02J3/38H02J3/12
CPCH02J3/36H02J3/381H02J3/12H02J2003/365H02J2300/20Y02E60/60
Inventor 杨张斌李钢彭代晓王仙荣罗代军蒋伟胡宗邱张斯翔
Owner CHINA THREE GORGES PROJECTS DEV CO LTD