CN104201683A - Flexible direct-current transmission system coupled transformer tap adjusting method - Google Patents
Flexible direct-current transmission system coupled transformer tap adjusting method Download PDFInfo
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- CN104201683A CN104201683A CN201410462756.8A CN201410462756A CN104201683A CN 104201683 A CN104201683 A CN 104201683A CN 201410462756 A CN201410462756 A CN 201410462756A CN 104201683 A CN104201683 A CN 104201683A
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Abstract
The invention discloses a flexible direct-current transmission system coupled transformer tap adjusting method. The method includes that when modulation degree of a converter surpasses the upper limit, a tap is adjusted towards the voltage direction of the coupling variable valve lowering side, and if adjustment fails, capacitive reactive instructions of the converter are actively reduced; when the modulation degree of the converter is lower than the upper limit, the tap is adjusted towards the voltage direction of the coupling variable valve rising side, and if adjustment fails, the capacitive reactive instructions of the converter are actively increased. By the method, the adjustment degree of the converter can be effectively adjusted even when the tap fails or the tap position surpasses the limits, and stable operation performance of the converter can be guaranteed.
Description
Technical field
The invention belongs to field of power electronics, particularly a kind of flexible DC power transmission system connection load tap changer control method.
Background technology
Flexible DC power transmission adopts voltage-source type converter, can control independently, fast active power and reactive power, thereby improves the stability of system, suppresses the fluctuation of system frequency and voltage, improves the steady-state behaviour of synchronization AC system.The fields such as flexible DC power transmission is grid-connected at new-energy grid-connected, distributed power generation, isolated island power supply, urban distribution network power supply have larger advantage, so the research of flexible DC power transmission correlation technique has great importance.
The connection transformer of DC transmission system generally adopts on-load voltage regulating switch pressure regulation, makes to connect transformer voltage on valve side fail safe and economy to guarantee that converter moves in suitable scope." change of current becomes on-load voltage regulating switch and controls " (Guangdong water conservancy and hydropower of Chen Wenyi and Yang Dongdong, the 6th phase in 2007,92～94) mentioned that the change of current becomes the Principles of Regulation of on-load voltage regulating switch and the tap-c hange control method of conventional DC transmission system, but because conventional direct current system and flexible direct current system converter differ greatly, the method is not also suitable for flexible direct current system.
During the converter stable operation of flexible direct current system, must guarantee its modulation degree (half ratio of valve side phase voltage fundametal compoment amplitude and DC bus-bar voltage, claim again modulation ratio) in the scope limiting, otherwise converter will bear excessive stress and bring excessive harmonic effects to system.The tap-c hange control method of flexible DC power transmission system there is not yet relevant report at present.
Summary of the invention
Object of the present invention, is to provide a kind of flexible DC power transmission system connection load tap changer control method, and while guaranteeing converter stable operation, modulation degree is in limited range.
In order to reach above-mentioned purpose, the technical solution used in the present invention is:
A flexible DC power transmission system connection load tap changer control method, step is as follows:
(1) whether the modulation degree that judges converter in limited range, as exceeds the upper limit and enters step (2), as entered step (5) lower than lower limit, otherwise enters step (1);
(2) toward reducing to connect, become voltage on valve side direction adjusting tap, enter step (3);
(3) judge whether tap regulates successfully, enter in this way step (1), otherwise enter step (4);
(4) initiatively reduce the capacitive reactive power instruction of converter, enter step (1);
(5) toward raising, connect and become voltage on valve side direction adjusting tap, enter step (6);
(6) judge whether tap regulates successfully, enter in this way step (1), otherwise enter step (7);
(7) initiatively increase the capacitive reactive power instruction of converter, enter step (1);
The modulation degree of the middle judgement of above-mentioned steps (1) converter exceeds the upper limit and adopts stagnant ring manner of comparison, when being greater than upper limit value Mmax, modulation degree judges that modulation degree exceeds the upper limit, when modulation degree is less than when upper limit value Mmax deducts ring width definite value Hsyt1, judge that modulation degree does not exceed the upper limit, otherwise keep original modulation degree whether to exceed the judgement of the upper limit; The modulation degree of judgement converter adopts stagnant ring manner of comparison lower than lower limit, when being less than lower limit value Mmin, modulation degree judges that modulation degree is lower than lower limit, when modulation degree is greater than when upper limit value Mmin adds ring width definite value Hsyt2, judge that modulation degree is not less than lower limit, otherwise keep original modulation degree whether lower than the judgement of lower limit.
In above-mentioned modulation degree, the span of limit value Mmax is 0.01 to 1, the span of ring width definite value Hsyt1 is 0.001 to 0.5, the span of lower limit value Mmin is 0.01 to 1.5, and the span of ring width definite value Hsyt2 is 0.001 to 0.5, and Mmax-Hsyt1 should be greater than Mmin+Hsyt2.
In above-mentioned steps (3), judge whether tap regulates successful criterion to be: the tap-c hange control time surpasses the overtime definite value Ttcc1 of tap or in connection change voltage on valve side direction, tap gear is to threshold limit value toward reducing, and the overtime definite value Ttcc1 value of described tap is 1s to 1min.
Judge whether tap regulates successful criterion to be in above-mentioned steps (6): the tap-c hange control time surpass the overtime definite value Ttcc2 of tap or toward tap gear in the connection change voltage on valve side direction that raises to threshold limit value, the overtime definite value Ttcc2 value of described tap is 1s to 1min.
Adopt after such scheme, beneficial effect of the present invention is:
A kind of flexible DC power transmission system connection load tap changer control method provided by the invention, even when tap fault or gear are out-of-limit, also can guarantee that converter modulation degree is in limited range.
Accompanying drawing explanation
Fig. 1 is flexible DC power transmission system list station structure schematic diagram;
Wherein, figure (a) is for connecting the situation of load tap changer primary side pressure regulation, and figure (b) is for connecting the situation of load tap changer secondary side pressure regulation;
Fig. 2 is that the present invention connects load tap changer control method flow chart.
Embodiment
Below with reference to drawings and the specific embodiments, technical scheme of the present invention is elaborated.
Fig. 1 is flexible DC power transmission system list station structure schematic diagram, wherein Fig. 1 (a) comprises AC system S, connects transformer T and converter C, the on-load voltage regulation tap that connects transformer T is positioned at primary side, when regulating tap that first side winding is increased, correspondingly the voltage of secondary side will reduce, otherwise the voltage of secondary side will raise; Wherein Fig. 1 (b) comprises AC system S, connects transformer T ' and converter C, the on-load voltage regulation tap that connects transformer T ' is positioned at secondary side, when regulating tap that secondary side winding is reduced, correspondingly the voltage of secondary side will reduce, otherwise the voltage of secondary side will raise.
Fig. 2 is that the present invention connects load tap changer control method flow chart, and the situation that below adopts the on-load voltage regulation tap shown in Fig. 1 (a) to be positioned at primary side is that example is elaborated to this flow chart.Setting limit value Mmax in modulation degree is 0.95, and it is 0.75 that modulation degree is less than lower limit value Mmin, and ring width definite value Hsyt1 and ring width definite value Hsyt2 are 0.01, and the overtime definite value Ttcc1 of tap and the overtime definite value Ttcc2 of tap are 10s.
Suppose when initial that converter C stable operation and modulation degree are 0.85, method provided by the invention begins to judge modulation degree not to be carried out any operation and continues modulation degree is judged in limited range, until modulation degree exceeds the upper limit or lower than lower limit.When AC system S voltage raises or converter C command value changes and causes that modulation degree increases to while exceeding the upper limit 0.95, will enter and exceed upper limit branch, send subsequently and regulate tap instruction increase first side winding to make to connect transformer T secondary side lower voltage.When the modulation degree of tap-c hange control when success converter will reduce, modulation degree be reduced to be less than 0.94 before this order persistence send, in modulation degree, be reduced to after being less than 0.94 and will rejudge as the cancellation of instruction in modulation degree limited range; When tap cannot regulate because of fault, after surpassing 10s, modulation degree is reduced the capacitive reactive power instruction that initiatively reduces converter, or out-of-limit when judging gear, also the capacitive reactive power instruction that initiatively reduces converter reduces modulation degree, in modulation degree, is reduced to and is less than 0.94 rear modulation degree and will rejudges as in limited range.When AC system S lower voltage or converter C command value change while causing modulation degree lower than lower limit 0.75, will enter lower than lower limit branch, send subsequently and regulate tap instruction to reduce first side winding to make to connect the rising of transformer T secondary side voltage.When the modulation degree of tap-c hange control when success converter will raise, modulation degree be increased to be greater than 0.76 before this order persistence send, in modulation degree, be increased to after being greater than 0.76 and will rejudge as modulation degree instruction cancellation in limited range; When tap cannot regulate because of fault, after surpassing 10s, modulation degree is raise the capacitive reactive power instruction that initiatively increases converter, or out-of-limit when judging gear, also the capacitive reactive power instruction that initiatively increases converter raises modulation degree, in modulation degree, is increased to after being greater than 0.76 and will rejudges as modulation degree is in limited range.
It is to be noted, said method is equally applicable to the situation that the on-load voltage regulation tap shown in Fig. 1 (b) is positioned at secondary side, difference is by regulating the tap of secondary side to make to connect transformer T secondary side voltage, to raise when modulation degree surpasses upper limit Mmax, when modulation degree during lower than lower limit Mmin by regulating the tap of secondary side to make to connect transformer T secondary side lower voltage.
Above embodiment only, for explanation technological thought of the present invention, can not limit protection scope of the present invention with this, every technological thought proposing according to the present invention, and any change of doing on technical scheme basis, within all falling into protection range of the present invention.
Claims (5)
1. a flexible DC power transmission system connection load tap changer control method, is characterized in that, comprises the steps:
(1) whether the modulation degree that judges converter in limited range, as exceeds the upper limit and enters step (2), as entered step (5) lower than lower limit, otherwise enters step (1);
(2) toward reducing to connect, become voltage on valve side direction adjusting tap, enter step (3);
(3) judge whether tap regulates successfully, enter in this way step (1), otherwise enter step (4);
(4) initiatively reduce the capacitive reactive power instruction of converter, enter step (1);
(5) toward raising, connect and become voltage on valve side direction adjusting tap, enter step (6);
(6) judge whether tap regulates successfully, enter in this way step (1), otherwise enter step (7);
(7) initiatively increase the capacitive reactive power instruction of converter, enter step (1).
2. a kind of flexible DC power transmission system connection load tap changer control method as claimed in claim 1, it is characterized in that, the modulation degree of the middle judgement of above-mentioned steps (1) converter exceeds the upper limit and adopts stagnant ring manner of comparison, when being greater than upper limit value Mmax, modulation degree judges that modulation degree exceeds the upper limit, when modulation degree is less than when upper limit value Mmax deducts ring width definite value Hsyt1, judge that modulation degree does not exceed the upper limit, otherwise keep original modulation degree whether to exceed the judgement of the upper limit; The modulation degree of judgement converter adopts stagnant ring manner of comparison lower than lower limit, when being less than lower limit value Mmin, modulation degree judges that modulation degree is lower than lower limit, when modulation degree is greater than when upper limit value Mmin adds ring width definite value Hsyt2, judge that modulation degree is not less than lower limit, otherwise keep original modulation degree whether lower than the judgement of lower limit.
3. a kind of flexible DC power transmission system connection load tap changer control method as claimed in claim 2, it is characterized in that, in described modulation degree, the span of limit value Mmax is 0.01 to 1.5, the span of ring width definite value Hsyt1 is 0.001 to 0.5, the span of lower limit value Mmin is 0.01 to 1, the span of ring width definite value Hsyt2 is 0.001 to 0.5, and Mmax-Hsyt1 should be greater than Mmin+Hsyt2.
4. a kind of flexible DC power transmission system connection load tap changer control method as claimed in claim 1, it is characterized in that, in described step (3), judge whether tap regulates successful criterion to be: the tap-c hange control time surpasses the overtime definite value Ttcc1 of tap or in connection change voltage on valve side direction, tap gear is to threshold limit value toward reducing, and the overtime definite value Ttcc1 value of described tap is 1s to 1min.
5. a kind of flexible DC power transmission system connection load tap changer control method as claimed in claim 1, it is characterized in that, judge whether tap regulates successful criterion to be in described step (6): the tap-c hange control time surpass the overtime definite value Ttcc2 of tap or toward tap gear in the connection change voltage on valve side direction that raises to threshold limit value, the overtime definite value Ttcc2 value of described tap is 1s to 1min.
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Cited By (5)
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| CN105429150A (en) * | 2014-09-16 | 2016-03-23 | Abb技术有限公司 | Voltage control system |
| CN109672183A (en) * | 2017-10-13 | 2019-04-23 | 贵州电网有限责任公司电力调度控制中心 | A kind of flexible direct current loop network system connection transformer tap head adjusting method |
| CN110061509A (en) * | 2019-05-22 | 2019-07-26 | 国家电网有限公司 | On-load voltage regulation control method and system for transformer in flexible direct current system |
| CN110391668A (en) * | 2019-07-16 | 2019-10-29 | 广东电网有限责任公司 | Consider the flexible HVDC transmission system change of current variation connector adjusting method of current limit |
| CN112595996A (en) * | 2020-11-26 | 2021-04-02 | 云南电网有限责任公司电力科学研究院 | Gear determining method of transformer |
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| CN105429150A (en) * | 2014-09-16 | 2016-03-23 | Abb技术有限公司 | Voltage control system |
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| CN110061509A (en) * | 2019-05-22 | 2019-07-26 | 国家电网有限公司 | On-load voltage regulation control method and system for transformer in flexible direct current system |
| CN110061509B (en) * | 2019-05-22 | 2020-09-29 | 国家电网有限公司 | On-load voltage regulation control method and system for transformer in flexible direct current system |
| CN110391668A (en) * | 2019-07-16 | 2019-10-29 | 广东电网有限责任公司 | Consider the flexible HVDC transmission system change of current variation connector adjusting method of current limit |
| CN112595996A (en) * | 2020-11-26 | 2021-04-02 | 云南电网有限责任公司电力科学研究院 | Gear determining method of transformer |
| CN112595996B (en) * | 2020-11-26 | 2022-08-26 | 云南电网有限责任公司电力科学研究院 | Gear determining method of transformer |
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