CN101752848B - Blocking judging method for excess voltage protection of extra-high voltage line - Google Patents
Blocking judging method for excess voltage protection of extra-high voltage line Download PDFInfo
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- CN101752848B CN101752848B CN2010100463096A CN201010046309A CN101752848B CN 101752848 B CN101752848 B CN 101752848B CN 2010100463096 A CN2010100463096 A CN 2010100463096A CN 201010046309 A CN201010046309 A CN 201010046309A CN 101752848 B CN101752848 B CN 101752848B
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Abstract
The invention relates to the excess voltage protection of an extra-high voltage line, in particular to a blocking judging method for the excess voltage protection of the extra-high voltage line. The method is characterized by comprising the following steps of: a. respectively measuring the current voltage frequency and the phase voltage of the line; b. judging whether the phase voltage is higher than or equal to a threshold value and simultaneously judging whether the voltage frequency is lower than or equal to the threshold value; and c. when the phase voltage is higher than or equal to the threshold value and the voltage frequency is lower than or equal to the threshold value, sending a blocking signal to a protection switch, and if not, not sending the blocking signal. The method can effectively avoid the amplification effect generated by CVT when the oscillation frequency of the line is lower than the working frequency of 50 Hz, namely, a voltage measured value obtained by CVT is comparatively higher than an actual value obtained according to the conversion of a rated transformation ratio, and the malfunction of the protection switch is caused when the voltage measured value exceeds the threshold value of excess voltage protection.
Description
Technical field
The present invention relates to the overvoltage protection in the supertension line, especially blocking judging method for excess voltage protection of extra-high voltage line.
Background technology
Capacitance type potential transformer (CVT) is made up of capacitor voltage divider and intermediate voltage electromagnetic unit; Can take into account the function of the two kinds of equipment of coupling capacitor in voltage transformer and the power circuit carrier-frequency coupling device, simultaneously reliable damping ferro resonance and possess good advantages such as transient response characteristic again in practical application.Existing excess voltage protection of extra-high voltage line is measured through CVT, obtains its output valve according to nominal transformation ratio; As the overvoltage protection criterion, if measurement result surpasses setting value, then overvoltage protection action; After certain time-delay, if main protection correct operation not then sends trip command by overvoltage protection; Then circuit breaker open failure circuit makes system, circuit avoid superpotential harm.
Although in the normal use of CVT, embody its unique advantages, very important is; It is bigger in harmonic content that it works as system works; Or during system frequency lower (oscillatory process of transient state), certain change can take place in its progress of disease characteristic, thereby influences the correct operation of relaying protection.
In actual extra high voltage system, when two transmission lines through the anti-π of the height no-load running that is connected together, if when nonloaded line need excise in system; In the transient process after excision, because the energy storage effect of the direct-to-ground capacitance of circuit, the voltage on the circuit bus can produce vibration; Frequency of oscillation may underfrequency, because the capacitive reactance of CVT dividing potential drop electric capacity under different frequency is different, receives the saturated influence of electromagnetic unit in addition; Cause certain overvoltage occurring at circuit; And when the circuit frequency of oscillation was lower than power frequency 50Hz, CVT can produce enlarge-effect, and it is bigger than normal that the voltage measuring value that promptly obtains through CVT compares the actual value that obtains by the nominal transformation ratio conversion; Surpass the threshold value of overvoltage protection, and then make this protection produce malfunction.According to practical operating experiences and relevant accident report, repeatedly occurred thisly because of the CVT enlarge-effect causes the accident of overvoltage protection mistake malfunction, exert a certain influence.
Summary of the invention
The purpose of this invention is to provide a kind of blocking judging method for excess voltage protection of extra-high voltage line, the protection switch misoperation of using this method can avoid the enlarge-effect because of CVT to cause.
For realizing above-mentioned purpose, the technical scheme that the present invention adopts is:
A kind of blocking judging method for excess voltage protection of extra-high voltage line, its special feature is, comprises the steps:
A, measure the current electric voltage frequency and the phase voltage of circuit respectively;
B, whether judge phase voltage, judge that simultaneously whether electric voltage frequency is smaller or equal to threshold value more than or equal to threshold value;
C,, send block signal to protection switch, otherwise be failure to actuate during more than or equal to threshold value and electric voltage frequency when phase voltage smaller or equal to threshold value.
Wherein the threshold value of phase voltage is 110% of a rated voltage, and the threshold value of electric voltage frequency is 80% of a power frequency.
The inventive method needs measuring frequency and voltage signal simultaneously;, frequency and voltage just provides the actuating signal of protection switch when all being in setting range; Therefore in the time of can effectively avoiding being lower than power frequency 50Hz because of the circuit frequency of oscillation; CVT produces enlarge-effect, and the voltage measuring value that promptly obtains through CVT is bigger than normal than the actual value that obtains by the nominal transformation ratio conversion, thus the protection switch misoperation that causes when surpassing the threshold value of overvoltage protection.
Description of drawings
Accompanying drawing 1 is the logic theory block diagram of the device of realization the inventive method;
Accompanying drawing 2 is the schematic circuit of embodiment 1, and wherein L1, L2 represent the 750kV circuit, and Q1, Q2, Q3, Q4, Q5 represent circuit breaker.
Embodiment
As shown in Figure 1, provided the constituent relation of overvoltage protection locking, it mainly comprises frequency measurement unit, voltage measurement unit, logic discrimination unit, locking unit and overvoltage protection unit.Through CVT, at first measure the line voltage distribution frequency by frequency measurement unit, measure the current phase voltage of circuit by voltage measurement unit then; Be sent to the logic discrimination unit, differentiate logic if satisfy, locking unit sends instruction; Locking overvoltage protection unit, thus the misoperation of protecting effectively avoided.
Wherein crucial logic discrimination unit adopts the perunit value of frequency and voltage; Voltage measuring value (below use all be perunit value) is " 1 " greater than its threshold value logic determines; Frequency measurement is " 1 " less than its threshold value logic determines; Final judgement relation is carried out and computing for both, and promptly both occur simultaneously, just with the overvoltage protection locking.
The threshold value of voltage and frequency can be adjusted according to concrete circuit voluntarily, and under normal operation conditions, the overvoltage protection locking will be opened.
Embodiment 1
Shown in accompanying drawing 2, two 750kV circuit L1 and circuit L2 are connected together through the high anti-π of transformer station, and whole system is the no-load running state, and right-hand member is supplied power by single ended power supply.
1) according to the dispatch command of system, to carry out and cut the ceases to be busy operation, i.e. system's tripping circuit breaker Q 1 is promptly excised nonloaded line L1 and circuit L2;
2) the voltage generation low-frequency oscillation (this routine frequency of oscillation is 40Hz) on this moment circuit L1 and circuit L2; And record the threshold value (this routine phase voltage threshold value be made as 110%, frequency threshold value be made as 80%) of the overvoltage of appearance through CVT above circuit L1 and circuit L2 overvoltage protection;
3) frequency detecting unit and the voltage detection unit at circuit L1 and circuit L2 two ends are all located at this moment
In the logical one state, the logic discrimination unit sends instruction, and locking unit carries out locking with the overvoltage protection unit;
4) the overvoltage protection locking promptly is opened, and its time time-delay is less than the time-delay of overvoltage protection.
Even the data that this moment, overvoltage protection recorded are higher than its threshold value, overvoltage protection can not moved yet.
It is simple that the inventive method has formation, is easy to advantages such as realization, can directly on equipment, realize through programming.The examination of this device is applied in many 750kV line overvoltage protections, can effectively avoid the overvoltage protection misoperation through the emulation proof.
Claims (2)
1. a blocking judging method for excess voltage protection of extra-high voltage line is characterized in that, comprises the steps:
A, measure the current electric voltage frequency and the phase voltage of circuit respectively;
B, whether judge phase voltage, judge that simultaneously whether electric voltage frequency is smaller or equal to threshold value more than or equal to threshold value;
C,, send block signal to protection switch, otherwise be failure to actuate during more than or equal to threshold value and electric voltage frequency when phase voltage smaller or equal to threshold value.
2. blocking judging method for excess voltage protection of extra-high voltage line as claimed in claim 1 is characterized in that:
Wherein the threshold value of phase voltage is 110% of a rated voltage, and the threshold value of electric voltage frequency is 80% of a power frequency.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010100463096A CN101752848B (en) | 2010-01-12 | 2010-01-12 | Blocking judging method for excess voltage protection of extra-high voltage line |
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| Application Number | Priority Date | Filing Date | Title |
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| CN2010100463096A CN101752848B (en) | 2010-01-12 | 2010-01-12 | Blocking judging method for excess voltage protection of extra-high voltage line |
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| Publication Number | Publication Date |
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| CN101752848A CN101752848A (en) | 2010-06-23 |
| CN101752848B true CN101752848B (en) | 2012-05-23 |
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| CN2010100463096A Active CN101752848B (en) | 2010-01-12 | 2010-01-12 | Blocking judging method for excess voltage protection of extra-high voltage line |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| GB2501057B (en) * | 2012-03-05 | 2014-09-17 | Alstom Technology Ltd | Method of fault clearance |
| CN105071347B (en) * | 2015-07-17 | 2018-01-19 | 国网山东省电力公司电力科学研究院 | Prevent transfer overvoltage from causing the blocking method of generator stator ground false protection |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1588737A (en) * | 2004-09-17 | 2005-03-02 | 福州大学 | Same lever/parallel double loop high resistance earthing protecting method and device |
| CN101237148A (en) * | 2008-01-23 | 2008-08-06 | 南京南瑞继保电气有限公司 | Low-frequency surge detection and protection method and device for power system |
| CN101420210A (en) * | 2008-12-02 | 2009-04-29 | 无敌科技(西安)有限公司 | Volume regulating device and method thereof |
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2010
- 2010-01-12 CN CN2010100463096A patent/CN101752848B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1588737A (en) * | 2004-09-17 | 2005-03-02 | 福州大学 | Same lever/parallel double loop high resistance earthing protecting method and device |
| CN101237148A (en) * | 2008-01-23 | 2008-08-06 | 南京南瑞继保电气有限公司 | Low-frequency surge detection and protection method and device for power system |
| CN101420210A (en) * | 2008-12-02 | 2009-04-29 | 无敌科技(西安)有限公司 | Volume regulating device and method thereof |
Non-Patent Citations (1)
| Title |
|---|
| JP平10-243548A 1998.09.11 |
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