CN104201683B - 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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- CN104201683B CN104201683B CN201410462756.8A CN201410462756A CN104201683B CN 104201683 B CN104201683 B CN 104201683B CN 201410462756 A CN201410462756 A CN 201410462756A CN 104201683 B CN104201683 B CN 104201683B
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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, adjust particularly to a kind of flexible direct current power transmission system connection load tap changer
Section method.
Background technology
Flexible DC power transmission adopts voltage source converter, can independently, quick control control active power and idle work(
Rate, thus improving the stability of system, the fluctuation of suppression system frequency and voltage, improves the steady-state behaviour of synchronization AC system.
Flexible DC power transmission is in new-energy grid-connected, distributed power generation is grid-connected, island with power, urban distribution network are powered etc., and that field has is larger
Advantage, the research of therefore flexible DC power transmission correlation technique has great importance.
The connection transformator of DC transmission system typically adopts on-load voltage regulating switch pressure regulation, makes connection transformator voltage on valve side
To ensure safety and the economy of inverter operation in suitable scope.Chen Wenyi and Yang Dongdong " change of current become have load adjust
Compress switch control " (Guangdong water conservancy and hydropower, the 6th phase in 2007,92～94) be referred to the change of current become on-load voltage regulating switch regulation former
Reason and the tap-c hange control method of customary DC transmission system, but because customary DC system and flexible direct current system inverter are poor
Different larger, the method is not particularly suited for flexible direct current system.
Its modulation degree (valve side phase voltage fundametal compoment amplitude is must assure that during the inverter stable operation of flexible direct current system
With the ratio of DC bus-bar voltage half, also known as modulation ratio) limit in the range of, otherwise inverter will bear excessive stress
And bring excessive harmonic effects to system.The tap-c hange control method of flexible direct current power transmission system is there is not yet related report at present
Road.
Content of the invention
The purpose of the present invention, is to provide a kind of flexible direct current power transmission system connection transformer tap head adjusting method, protects
During card inverter stable operation, modulation degree is in the range of limiting.
In order to reach above-mentioned purpose, the technical solution used in the present invention is：
A kind of flexible direct current power transmission system connects transformer tap head adjusting method, and step is as follows：
(1) whether the modulation degree judging inverter, in the range of limiting, such as enters step (2) beyond the upper limit, is such as less than down
Limit enters step (5), otherwise enters step (1)；
(2) toward reducing connection change voltage on valve side direction regulation tap, enter step (3)；
(3) judge whether tap adjusts successfully, enter step (1) in this way, otherwise enter step (4)；
(4) actively reduce the capacitive reactive power instruction of inverter, enter step (1)；
(5) toward raising connection change voltage on valve side direction regulation tap, enter step (6)；
(6) judge whether tap adjusts successfully, enter step (1) in this way, otherwise enter step (7)；
(7) actively increase the capacitive reactive power instruction of inverter, enter step (1)；
Judge in above-mentioned steps (1) that the modulation degree of inverter exceeds the upper limit and adopts stagnant ring manner of comparison, when modulation degree is more than
Judge during upper limit value Mmax that modulation degree exceeds the upper limit, when modulation degree deducts ring width definite value Hsyt1 less than upper limit value Mmax
Judge modulation degree without departing from the upper limit, when above-mentioned two situations are all unsatisfactory for, keep whether degree of being originally modulated exceeds the judgement of the upper limit；
Judge that the modulation degree of inverter is less than lower limit and adopts stagnant ring manner of comparison, when modulation degree is less than lower limit value Mmin
Judge that modulation degree is less than lower limit, judge that modulation degree is not low when modulation degree is more than when lower limit value Mmin adds ring width definite value Hsyt2
In lower limit, when above-mentioned two situations are all unsatisfactory for, keep whether degree of being originally modulated is less than the judgement of lower limit.
In above-mentioned modulation degree, the span of limit value Mmax is 0.01 to 1, and the span of ring width definite value Hsyt1 is
The span of 0.001 to 0.5, lower limit value Mmin is 0.01 to 1.5, the span of ring width definite value Hsyt2 be 0.001 to
0.5, and Mmax-Hsyt1 should be greater than Mmin+Hsyt2.
Judge whether tap adjusts successful criterion and be in above-mentioned steps (3)：The tap-c hange control time exceedes tap
Overtime definite value Ttcc1 or toward reduce connection become voltage on valve side direction on tap gear to threshold limit value, described tap surpass
When definite value Ttcc1 value be 1s to 1min.
Judge whether tap adjusts successful criterion and be in above-mentioned steps (6)：The tap-c hange control time exceedes tap
Overtime definite value Ttcc2 or toward raise connection become voltage on valve side direction on tap gear to threshold limit value, described tap surpass
When definite value Ttcc2 value be 1s to 1min.
After such scheme, beneficial effects of the present invention are：
A kind of flexible direct current power transmission system connection transformer tap head adjusting method that the present invention provides, even if tap event
Barrier or gear more in limited time, also can ensure inverter modulation degree in the range of limiting.
Brief description
Fig. 1 is flexible direct current power transmission system list station structure schematic diagram；
Wherein, figure (a) is the situation of connection load tap changer primary side pressure regulation, and figure (b) is connection load tap changer
The situation of secondary side pressure regulation；
Fig. 2 is present invention connection transformer tap head adjusting method flow chart.
Specific embodiment
Below with reference to drawings and the specific embodiments, technical scheme is described in detail.
Fig. 1 is flexible direct current power transmission system list station structure schematic diagram, and wherein Fig. 1 (a) includes AC system S, connection transformation
Device T and inverter C, the on-load voltage regulation tap of connection transformator T is located at primary side, so that first side winding is increased when adjusting tap
The voltage of added-time correspondingly secondary side will reduce, otherwise the voltage of secondary side will raise；Wherein Fig. 1 (b) inclusion AC system S,
Connection transformator T ' and inverter C, the on-load voltage regulation tap of connection transformator T ' is located at secondary side, makes two when adjusting tap
When secondary side winding reduces, correspondingly the voltage of secondary side will reduce, otherwise the voltage of secondary side will raise.
Fig. 2 connects transformer tap head adjusting method flow chart for the present invention, below adopts the load that has shown in Fig. 1 (a) to adjust
Pressure tap is described in detail to this flow chart in case of being located at primary side.Set in modulation degree limit value Mmax as
0.95, 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, tap
Overtime definite value Ttcc1 and tap time-out definite value Ttcc2 are 10s.
When assuming initial, inverter C stable operation and modulation degree are 0.85, and the method that the present invention provides begins to judge to modulate
Degree does not execute in the range of limiting and any operate and continue modulation degree is judged, until modulation degree exceeds the upper limit or be less than down
Limit.When AC system S voltage raises or inverter C instruction value changes cause modulation degree to increase to beyond the upper limit 0.95, will
Enter and exceed upper limit branch, subsequently sending regulation tap instruction increase first side winding makes connection transformator T secondary side voltage
Reduce.When tap-c hange control success, the modulation degree of inverter will reduce, and this instruction before modulation degree decreases below 0.94 is held
Supervention goes out, and will rejudge after modulation degree decreases below 0.94 is that instruction is cancelled in the range of modulation degree limits；Work as tap
Head for some reason barrier when cannot adjust, instructing more than the capacitive reactive power actively being reduced inverter after 10s makes modulation degree reduction, or ought
Judge that gear is out-of-limit, the capacitive reactive power instruction also actively reducing inverter makes modulation degree reduce, and is reduced to little in modulation degree
After 0.94, modulation degree will rejudge is in the range of limiting.When AC system S voltage reduces or the change of inverter C command value
When change causes modulation degree to be less than lower limit 0.75, it is less than lower limit branch by entering, subsequently send regulation tap instruction minimizing once
Side winding makes connection transformator T secondary side voltage raise.When tap-c hange control success, the modulation degree of inverter will raise, and adjust
Before system raises to above 0.76, this order persistence sends, and will rejudge as modulation degree after modulation degree raises to above 0.76
In the range of limiting, instruction is cancelled；When tap hinders for some reason and cannot adjust, more than the capacitive actively being increased inverter after 10s
Idle instruction makes modulation degree raise, or when judging that gear is out-of-limit, the capacitive reactive power instruction also actively increasing inverter makes
Modulation degree raises, and will rejudge as modulation degree after modulation degree raises to above 0.76 in the range of limiting.
It is pointed out that said method is equally applicable to the on-load voltage regulation tap shown in Fig. 1 (b) is located at secondary side
Situation, difference is to make connection transformator T bis- times when modulation degree exceedes upper limit Mmax by adjusting the tap of secondary side
Side voltage raises, and makes connection transformator T secondary side electricity when modulation degree is less than lower limit Mmin by adjusting the tap of secondary side
Pressure drop is low.
Above example technological thought only to illustrate the invention is it is impossible to limit protection scope of the present invention with this, every
According to technological thought proposed by the present invention, any change done on the basis of technical scheme, each fall within the scope of the present invention
Within.
Claims (5)
1. a kind of flexible direct current power transmission system connection transformer tap head adjusting method is it is characterised in that comprise the steps：
(1) whether the modulation degree judging inverter, in the range of limiting, such as enters step (2) beyond the upper limit, such as enters less than lower limit
Enter step (5), otherwise enter step (1)；
(2) toward reducing connection change voltage on valve side direction regulation tap, enter step (3)；
(3) judge whether tap adjusts successfully, enter step (1) in this way, otherwise enter step (4)；
(4) actively reduce the capacitive reactive power instruction of inverter, enter step (1)；
(5) toward raising connection change voltage on valve side direction regulation tap, enter step (6)；
(6) judge whether tap adjusts successfully, enter step (1) in this way, otherwise enter step (7)；
(7) actively increase the capacitive reactive power instruction of inverter, enter step (1).
2. a kind of flexible direct current power transmission system connects transformer tap head adjusting method as claimed in claim 1, and its feature exists
In the middle modulation degree judging inverter of above-mentioned steps (1) exceeds the upper limit and adopts stagnant ring manner of comparison, when modulation degree is more than upper restriction
Judge during value Mmax that modulation degree exceeds the upper limit, judge when modulation degree deducts ring width definite value Hsyt1 less than upper limit value Mmax to adjust
System, without departing from the upper limit, when above-mentioned two situations are all unsatisfactory for, keeps whether degree of being originally modulated exceeds the judgement of the upper limit；
Judge that the modulation degree of inverter is less than lower limit and adopts stagnant ring manner of comparison, judge when modulation degree is less than lower limit value Mmin
Modulation degree is less than lower limit, judges that modulation degree is not less than down when modulation degree is more than when lower limit value Mmin adds ring width definite value Hsyt2
Limit, when above-mentioned two situations are all unsatisfactory for, keeps whether degree of being originally modulated is less than the judgement of lower limit.
3. a kind of flexible direct current power transmission system connects transformer tap head adjusting method as claimed in claim 2, and its feature exists
In in described modulation degree, the span of limit value Mmax is 0.01 to 1.5, and 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, and 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 direct current power transmission system connects transformer tap head adjusting method as claimed in claim 1, and its feature exists
In described step (3) is middle to judge whether tap adjusts successful criterion and be：It is fixed that the tap-c hange control time exceedes tap time-out
Value Ttcc1 or become on voltage on valve side direction tap gear to threshold limit value toward reducing connection, described tap time-out definite value
Ttcc1 value is 1s to 1min.
5. a kind of flexible direct current power transmission system connects transformer tap head adjusting method as claimed in claim 1, and its feature exists
In described step (6) is middle to judge whether tap adjusts successful criterion and be：It is fixed that the tap-c hange control time exceedes tap time-out
Value Ttcc2 or become on voltage on valve side direction tap gear to threshold limit value toward raising connection, described tap time-out definite value
Ttcc2 value is 1s to 1min.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| EP2942796B1 (en) * | 2014-09-16 | 2016-12-21 | ABB Schweiz AG | 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 |
| 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 |
| CN110391668B (en) * | 2019-07-16 | 2020-07-14 | 广东电网有限责任公司 | Current limit value-considered converter transformer sub-joint adjusting method for flexible direct current transmission system |
| 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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| CN103532126A (en) * | 2013-10-24 | 2014-01-22 | 国家电网公司 | Method for controlling main circuit parameters in two-end flexible direct current transmission system |
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| KR100795752B1 (en) * | 2006-07-06 | 2008-01-21 | 명지대학교 산학협력단 | Voltage source converter system with pulse-interleaving auxiliary circuit for HVDC application |
| CN102354995B (en) * | 2011-09-28 | 2013-12-11 | 广东省电力调度中心 | Control method and control system for VQC (voltage quality control) of transformer substation |
| CN102801170B (en) * | 2012-08-07 | 2014-07-23 | 广东电网公司中山供电局 | Reactive-voltage control method and system of regional power-grid substations |
| CN103166226B (en) * | 2013-03-29 | 2015-01-28 | 华北电力大学（保定） | Network voltage reactive-power compound coordination control system and method for new energy power generation |
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| 基于二极管箝位型五电平换流器的柔性直流输电系统研究;国洪觅;《CNKI优秀硕士学位论文全文库》;20120715;第37页 * |
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