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A Control Method for Reducing Frequent Filter Switching in Hybrid DC Transmission System

A power transmission system, hybrid DC technology, applied in AC network circuits, reducing/preventing power oscillation, circuit devices, etc., can solve problems affecting the stability of DC transmission systems, bus voltage fluctuations in AC systems, frequent switching of filters, etc. Achieve the effects of reducing frequent switching problems, improving power quality, reducing the number of fluctuations and the range of fluctuations

Active Publication Date: 2020-07-14
GUANGDONG POWER GRID CO LTD +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the capacity of the AC filter group is a fixed value, when the active power level of the DC transmission system is low during the start-up phase or normal operation phase, the reactive power generated by the input filter cannot be used for the consumption of conventional DC unit converters. On the other hand, when the unbalanced reactive power balance of the DC system is near the set value area, frequent switching of the filter will occur, which is easy to Cause AC system bus voltage fluctuation and system oscillation, affecting the stability of DC transmission system

Method used

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  • A Control Method for Reducing Frequent Filter Switching in Hybrid DC Transmission System
  • A Control Method for Reducing Frequent Filter Switching in Hybrid DC Transmission System

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[0042] The accompanying drawings are for illustrative purposes only and cannot be construed as limiting the patent;

[0043] In order to better illustrate this embodiment, some parts in the drawings will be omitted, enlarged or reduced, and do not represent the size of the actual product;

[0044] For those skilled in the art, it is understandable that some well-known structures and descriptions thereof may be omitted in the drawings.

[0045] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0046] Most of the converter stations that have been put into operation meet the reactive power and harmonic filtering requirements of the conventional DC unit through switching of the filter group, but the switching of the filter is completed through voltage regulation or reactive power regulation , are all differential adjustments, especially in the vicinity of the control fixed value area, ...

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Abstract

The invention discloses a control method for reducing frequent switching of a filter in a hybrid direct current transmission system, and relates to the technical field of filter switching control. Themethod comprises the following steps of: calculating an unbalanced reactive power difference; comparing unbalanced reactive power and the upper limit value of input reactive power capacity of an AC filter and the lower limit value of excision reactive power capacity of the AC filter; determining whether the reactive power emitted by a flexible direct current unit reaches a limit value or not, ifyes, performing delay for a while, switching the filter small group, or else, modifying the reactive power target value of the flexible direct current unit; and calculating the value of the reactive power extra emitted by the flexible direct current unit, and feeding back the control result to a DC station control device. Through cooperation of the reactive power adjustment control of the AC filter and the flexible direct current unit, the smooth adjusting of the reactive power is achieved, the unbalanced reactive power difference of the conventional DC unit deviates from the fixed value areato reduce the number of switching times of the AC filter and improve the system stability.

Description

technical field [0001] The invention relates to the technical field of filter switching control, and more particularly, relates to a control method for reducing frequent switching of filters in a hybrid direct current transmission system. Background technique [0002] Flexible direct current transmission (VSC-HVDC) technology is based on voltage source converter, self-shutdown device and pulse width modulation (PWM) technology, which has fast response speed, good controllability, flexible operation mode, and can be transferred to passive network. The advantages of power supply without commutation failure are the hot spots in the development of power grid transmission technology. When VSC-HVDC is in normal operation, by adjusting the power angle difference between the amplitude of the converter outlet voltage and the system voltage, the output active power and reactive power can be independently controlled, which can improve the stability of the system and the power transmiss...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/36H02J3/18H02J3/24
CPCH02J3/1835H02J3/24H02J3/36H02J2003/365Y02E40/30Y02E60/60
Inventor 陈道品罗容波孔令生李新邱太洪宋安琪董镝潘志图李亮明范心明李慧王俊波李国伟唐琪黎小龙陈邦发王振霞康成
Owner GUANGDONG POWER GRID CO LTD
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