CN-115395531-B - Station-level reactive power control method of flexible direct current transmission system

CN115395531BCN 115395531 BCN115395531 BCN 115395531BCN-115395531-B

Abstract

The invention discloses a station-level reactive power control method of a flexible direct current transmission system, which comprises the steps of detecting and obtaining a voltage signal actual measurement value and a current signal actual measurement value of a public connection point of a convertor station, comparing an alternating current reactive component reference value of the public connection point of the convertor station with a q-axis component of the current signal actual measurement value, taking the difference value as a reactive current deviation value of the public connection point of the convertor station, obtaining a voltage compensation value of an alternating current near zone of the convertor station after the reactive current deviation value is subjected to K-time gain by a correction coefficient, comparing the alternating current voltage reference value with the voltage compensation value and the alternating current voltage actual measurement value, obtaining a reactive outer loop deviation value, obtaining an alternating current reactive component reference value after the reactive outer loop deviation value is subjected to PI regulation, and taking the alternating current reactive component reference value as input of inner loop control. The method can fully utilize the reactive power regulation capability of the flexible direct-current transmission system, can reduce the fluctuation frequency during reactive power compensation, and can also prevent the reactive power compensation from causing severe fluctuation.

Inventors

CAI HUI
ZHAO FEIFEI
LI ZHAOWEI
ZHANG WENJIA
LIU FUSUO
QI WANCHUN
PENG ZHUYI
HUANG HUI
HAN XINGNING
SUN ZHENYU
XU CAIXUAN
CHANG HAIJUN
Wang Chuochuo
WANG CHAO

Assignees

国网江苏省电力有限公司经济技术研究院
国电南瑞南京控制系统有限公司
国网江苏省电力有限公司

Dates

Publication Date: 20260505
Application Date: 20220914

Claims (7)

1. The station-level reactive power control method of the flexible direct current transmission system is characterized by comprising the following steps of: detecting and obtaining a voltage signal actual measurement value U s and a current signal actual measurement value I s of a common connection point of the converter station; The reference value I sqref of the reactive component of the alternating current of the common connection point of the convertor station is compared with the q-axis component I sq of the current signal actual measurement value I s , the difference value is used as the reactive current deviation delta I sq ,ΔI sq of the common connection point of the convertor station, and the voltage compensation delta U ref of the alternating current near zone of the convertor station is obtained after the correction coefficient K-time gain; Comparing the alternating current voltage reference value U ref with the voltage compensation quantity delta U ref and an alternating current voltage actual measurement value U s to obtain a reactive outer ring deviation quantity delta U, regulating the delta U through PI to obtain an alternating current reactive component reference value I sqref , and taking the alternating current reactive component reference value I sqref as input of inner ring control; The correction coefficient K=100l, l is a reactive compensation participation coefficient of the converter station, and the value range of l is (0, 1); the calculation formula of the voltage compensation quantity delta U ref of the alternating current near zone of the convertor station is as follows: ΔU ref ＝K*ΔI sq ; The ac voltage reference U ref is taken to be the voltage rating U set of the common connection point of the converter station.
2. The station-level reactive power control method of the flexible direct current transmission system according to claim 1, wherein the reactive outer loop deviation DeltaU is calculated according to the following formula: ΔU=U ref -ΔU ref -U s 。
3. The method for controlling station-level reactive power of a flexible direct current transmission system according to claim 2, wherein the station-level active power of the flexible direct current transmission system is controlled by constant active power or constant direct current voltage.
4. The method for station-level reactive power control of a flexible direct current transmission system as set forth in claim 3, wherein said fixed active power control comprises the following steps: Detecting to obtain an actual active power value P s of a public connection point of the convertor station, comparing the detected actual active power value P s with an active power reference value P ref , regulating the difference value by PI to obtain an active component reference value I sdref of alternating current, and taking an reactive component reference value I sdref of the alternating current as input of inner loop control; The constant direct current voltage control method comprises the following specific steps: The method comprises the steps of detecting a direct current line voltage actual measurement value U dc of a converter station, comparing the detected direct current line voltage actual measurement value U dc with a direct current line voltage reference value U dcref , regulating a difference value through PI to obtain an alternating current active component reference value I sdref , and taking the alternating current active component reference value I sdref as input of inner loop control.
5. The method for station-level reactive power control of a flexible direct current transmission system according to claim 4, wherein in the inner loop control, first, a d-axis component I sd of an actual measurement value of a current signal and a q-axis component I sq of the actual measurement value of the current signal are respectively compared with an ac active component reference value I sdref and an ac reactive component reference value I sqref , PI adjustments are respectively performed on differences, and the adjusted correction amounts are respectively calculated with a coupling term between d-axis currents and q-axis currents, a d-axis component U sd of an actual measurement value of a voltage signal and a q-axis component U sq of an actual measurement value of the voltage signal to obtain a d-axis component U cd of a converter station outlet voltage and a q-axis component U cq of the converter station outlet voltage, and then the d-axis component U cd of the converter station outlet voltage and the q-axis component U cq of the converter station outlet voltage are input to the SPWM.
6. The method for station-level reactive power control of a flexible direct current transmission system according to claim 5, wherein said d-axis component I sd of said actual measured current signal value and said q-axis component I sq of said actual measured current signal value are obtained by performing dq conversion on said actual measured current signal value I s .
7. The method for station-level reactive power control of a flexible direct current transmission system as set forth in claim 6, wherein the d-axis component U sd of the measured voltage signal value and the q-axis component U sq of the measured voltage signal value are obtained by performing dq conversion on the measured voltage signal value U s of the common connection point of the converter station.

Description

Station-level reactive power control method of flexible direct current transmission system Technical Field The invention belongs to the technical field of direct current transmission, and particularly relates to a station-level reactive power control method of a flexible direct current transmission system. Background With the development of the flexible direct current transmission system to higher voltage class, larger transmission capacity, multiport and networking, the flexible and reliable flexible direct current transmission system has wide application prospect. The existing flexible direct current system station level control strategy is mainly active-reactive decoupling control, wherein reactive control links are single, and the traditional reactive control method mainly comprises two control modes of fixed reactive power control and fixed alternating current voltage control, and specifically comprises the following steps: When the converter station is connected with an alternating current system, the active power is generally accurately delivered to be the highest priority under the normal working condition. When the voltage of the ac node to which the converter station is connected fluctuates, the voltage fluctuation needs to be suppressed quickly, so as to avoid the influence on the transmission of active power. At this time, if the conventional constant reactive power control is adopted and the reactive reference value is set to be 0, the suppression effect on the voltage fluctuation is relatively poor, meanwhile, the characteristics of flexible direct current transmission active power and reactive power flexible independent control are not brought into play, and the reactive power adjustment capability of a flexible direct current transmission system is not fully utilized, while if the conventional constant alternating current voltage control is adopted, the suppression of the voltage fluctuation is too frequent, so that frequent adjustment of reactive power can be caused, the rapid recovery of the system voltage is not facilitated, and meanwhile, the matching and the reasonable distribution of reactive power compensation equipment in a near area of a converter station are also not facilitated. Disclosure of Invention In order to solve the problems in the prior art, the invention provides a station-level reactive power control method of a flexible direct current transmission system. The technical scheme of the invention is as follows: A station-level reactive power control method of a flexible direct current transmission system comprises the following steps: detecting and obtaining a voltage signal actual measurement value U s and a current signal actual measurement value I s of a common connection point of the converter station; The reference value I sqref of the reactive component of the alternating current of the common connection point of the convertor station is compared with the q-axis component I sq of the current signal actual measurement value I s, the difference value is used as the reactive current deviation delta I sq,ΔIsq of the common connection point of the convertor station, and the voltage compensation delta U ref of the alternating current near zone of the convertor station is obtained after the correction coefficient K-time gain; After the alternating voltage reference value U ref is compared with the voltage compensation quantity delta U ref and the alternating voltage actual measurement value U s, the reactive outer ring deviation quantity delta U is obtained, the alternating current reactive component reference value I sqref is obtained after PI adjustment of the delta U, and the alternating current reactive component reference value I sqref is used as input of inner ring control. Further, the correction coefficient k=100l, l is a reactive compensation participation coefficient of the converter station, and the value range of l is (0, 1). Further, the calculation formula of the voltage compensation quantity Δu ref of the ac near zone of the converter station is as follows: ΔUref＝K*ΔIsq。 further, the calculation formula of the reactive outer ring deviation amount deltau is as follows: ΔU=Uref-ΔUref-Us。 further, the ac voltage reference U ref is taken as the voltage rating U set of the common connection point of the converter station. Further, station-level active control of the flexible direct current transmission system adopts fixed active power control or fixed direct current voltage control. Further, the fixed active power control comprises the following specific methods: Detecting to obtain an actual active power value P s of a public connection point of the convertor station, comparing the detected actual active power value P s with an active power reference value P ref, regulating the difference value by PI to obtain an active component reference value I sdref of alternating current, and taking an reactive component reference value I sdref of the alternating current as