CN102096008A - Method for judging wiring correctness of conventional transformer - Google Patents
Method for judging wiring correctness of conventional transformer Download PDFInfo
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- CN102096008A CN102096008A CN2009103115684A CN200910311568A CN102096008A CN 102096008 A CN102096008 A CN 102096008A CN 2009103115684 A CN2009103115684 A CN 2009103115684A CN 200910311568 A CN200910311568 A CN 200910311568A CN 102096008 A CN102096008 A CN 102096008A
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Abstract
The invention relates to a method for analyzing the wiring of a differential protection current transformer (CT) return circuit of the conventional transformer, which comprises the following steps of: 1) drawing a correct vector diagram of the return circuit, and drawing an actually-measured vector diagram based on reference voltage; 2) outputting an analytical result of the wiring correctness of the return circuit; 3) acquiring parameters required by the phase combining of a current transformer (CT) on each side of the differential protection return circuit of the conventional transformer; 4) drawing a vector diagram of an item selected by the CT on each side of the differential protection return circuit of the conventional transformer by a method of measuring in phase simultaneously on each side based on the reference voltage; and 5) performing conversion on a measured value of the differential protection CT return circuit of the conventional transformer according to the conventional transformer and the parameters of the conventional transformer, analyzing and judging a phase combining analytical result, and outputting the analytical result. The method has the advantages that: the analytical result is reliable, and the accuracy is improved substantially.
Description
Technical field
The present invention relates to relay protection CT circuit connection correctness analytical approach in a kind of electric system, relate in particular to a kind of wiring to conventional transformer differential protecting CT loop in the electric system whether correct, close the analytical approach of whether correctly analyzing, judge and provide the false wiring type mutually.
Background technology
Will satisfy to differ 120 ° between phase and phase for the correctness of single CT circuit connection, and phase sequence is identical, is positive sequence or negative phase-sequence, each phase current two sub-value is identical.It is identical with the primary current value in measurement loop that the current effective value of measuring according to secondary multiply by the primary current value that the CT transformation-ratio meter calculates.
For the conventional transformer differential protection, calculate the resultant vector of each phase of mains side and the resultant vector of each phase of load side.When each winding all satisfies the phase angle balance, promptly differ 120 ° between phase and phase, and phase sequence is identical, be positive sequence or negative phase-sequence.Simultaneously mains side and load side every mutually vector and when being zero, promptly amplitude equates, to differ 180 ° be that decidable conventional transformer differential protecting CT circuit connection is correct to angle.
The correctness of conventional transformer differential protecting CT circuit connection directly influences the normal operation of electric power system.The correctness of relay protection CT circuit connection is in time made analysis, judged; requisite important step during to be that transformer station is newly-built put into operation, overhaul; conventional transformer differential protecting CT circuit connection correctness is analyzed at present; main by manually carrying out Zhao especially main transformer, bus differential protecting CT loop; the staff will pass through a large amount of calculating; manual drawing current vector figure, and then draw the analysis result of relay protection CT circuit connection correctness according to result of calculation and vector plot.The The whole analytical process calculated amount is big, and needs the staff rule of thumb to judge, so there is the shortcoming that efficient is low, error is big.The flow process that the tradition manual method is analyzed relay protection CT circuit connection correctness is as follows:
1) obtains data: the current amplitude, phase data and the correlation parameter that obtain each each phase of winding of conventional transformer differential protecting CT loop.Generally obtain (as using two pincers volt-ampere phase meters), the measured value of current amplitude, phase data and the measurement loop measured is compared, judge the correctness of single CT circuit connection by power measuring instrument.For two circle main transformers, use two pincers volt-ampere phase meters measure successively each phase (A, B, C, N) current amplitude of high-pressure side CT and low-pressure side CT and phase place and with compared by situation to determine the correctness of each side CT circuit connection according to meritorious, idle the sending of measuring the loop.
2) calculate electric current: calculate the coefficient of balance of each side earlier according to rated voltage and CT no-load voltage ratio, and then current amplitude is converted according to coefficient of balance.
3) adjust phase place: current phase is adjusted according to the mode of connection.
4) draw vector plot: according to parameter manual drawing vector plots such as reference voltage, current amplitude, phase angles.
5) analysis and judgement: judge CT circuit connection correctness according to each side through current value after the EQUILIBRIUM CALCULATION FOR PROCESS and vector plot, if wiring error needs profiling error reason and correcting method.Judge according to the pacing items that mains side resultant vector and load side resultant vector should equal and opposite in directions, direction is opposite whether whole differential circuit wiring is correct.If incorrect, then rule of thumb judge by the staff, provide correction scheme, this step does not have the flow process of standard, fully by staff quality's decision, if there is not experience, judging so wastes time and energy, and is difficult to judge for complicated error situation.
Summary of the invention
For solve under the at present artificial situation conventional transformer differential protecting CT circuit connection error situation judged waste time and energy, to the demanding situation of staff, the invention provides the analysis and judgement method of a kind of reliability height, simple, easy to operate conventional transformer differential protecting CT circuit connection correctness safe in utilization.
The technical solution that the present invention solves the problems of the technologies described above is:
A kind of method of judging conventional transformer wiring correctness, its special character is: this method may further comprise the steps:
1) draws the correct vector plot in this loop; Draw the vector plot of actual measurement with reference voltage;
2) export this circuit connection correctness analysis result:
3) obtain each side CT of conventional transformer differential protection and close the phase desired parameters;
4) adopt the simultaneously-measured method of each side homophase to draw the vector plot of each side CT selected item of conventional transformer differential protection loop with reference voltage;
5) according to conventional transformer and parameter thereof conventional transformer differential protecting CT loop measured value is converted; Analyze, judge and close the facies analysis result, and the output analysis result:
5.1) calculate the coefficient of balance of each winding of conventional transformer;
5.2) according to the convert current effective value of this winding of the coefficient of balance of each winding of conventional transformer;
5.3) all current phases are deducted with the measurement loop is the phase power angle of reference;
5.4) judge whether reference voltage is Ua, if then direct execution in step 2.5); If not then reference voltage being converted to behind the Ua execution in step 2.5 again);
5.5) if conventional transformer differential protecting CT loop is analyzed, then to carry out causing the compensation of each side primary current phase difference owing to the difference of a winding connection mode of each side of conventional transformer.
The above step 5.1) computing method for the coefficient of balance of conventional transformer differential protection in are:
5.1.1) calculate the secondary rated current of each winding;
I is a winding primary side rated current; Ie is a winding secondary rated current; Nct is a winding CT no-load voltage ratio; Calculate the secondary rated current of each winding according to above-mentioned formula two;
5.1.2) one coefficient of balance establishing a rated current maximum of each winding is 1, converts the coefficient of balance of other windings;
5.1.3) coefficient of balance should be smaller or equal to 4, if having in each lateral balance coefficient greater than 4, so it are made as 4, again the coefficient of balance of other windings is changed.
The above step 5.2) computing method of conventional transformer differential protection coefficient of balance are in:
Become example with two circles, have according to formula two:
Wherein, Ihe is the high-pressure side rated current; Uh is the high-pressure side rated voltage; Nhct is a high-pressure side CT no-load voltage ratio; Ile is the low-pressure side rated current; Ul is the low-pressure side rated voltage; Nlct is a low-pressure side CT no-load voltage ratio; With the high-pressure side is benchmark, calculates the coefficient of balance of other windings, and promptly establishing high-pressure side coefficient of balance Kh is 1, then low-pressure side coefficient of balance Kl=(Uh * Nhct)/(Ul * Nlct); Can calculate in like manner that three circles become or each winding during other situation
Advantage of the present invention is as follows:
The reliable accuracy of analysis result significantly improves.The analytical approach in relay protection of power system CT provided by the present invention loop is carried out twice analysis; judge at each CT loop and the differential CT of conventional transformer loop; can provide perfect wiring error situation and correction scheme in the final analysis result that forms; need not again the people for judging; its analysis result reliability obviously analytical approach than traditional is strong; and not influenced by aspects such as subjective quality of staff and objective environment factor, make precision of analysis significantly improve.
Simple to operate, safe and reliable.The present invention oversimplifies the analytical work of electric relay protection CT circuit connection, only need simply measure and can analyze and provide the result automatically, and staff's technical merit is required significantly to reduce.
The input of 4 road electric currents is arranged, can carry out the measurement of 4 road current amplitudes, phase place simultaneously at most, measure when satisfying 4 current return amplitudes of transformer and phase place at most, guaranteed to close the accuracy of phase time data, avoided owing to load in the measuring process changes, passes through the mistake of closing the phase result that power flow direction changes and causes.
Description of drawings
Schematic flow sheet for connection analysis method provided by the present invention;
Fig. 1 is for the present invention is meritorious, the idle synoptic diagram that concerns that is subjected to situation and quadrant that send.
Embodiment
The idiographic flow that the invention provides a kind of conventional transformer differential protecting CT circuit connection correctness analytical approach wiring analysis is as follows:
1, obtain the basis for estimation of judging protection CT circuit connection correctness:
Meritorious, idle send, be subjected to situation by what the transformer station of measuring loop, stoichiometric point or interrelate with it obtained this loop, meritorious, idle sending according to this loop are subjected to the correct phase angle of definite this unit secondary such as situation, primary current effective value and the effective value of electric current, need select a reference voltage when measuring, the current phase of being surveyed is meant the phase place of tested electric current with respect to this reference voltage.Reference voltage can be selected by the operator when measuring voluntarily.
2, according to the basis for estimation the obtained correct vector plot that draws:
For example: pass through measurement loop, stoichiometric point or the transformer station that interrelates with it obtain the meritorious of this loop, idle send that to be subjected to situation be that (sending and being subjected to situation is benchmark with the bus, flow into bus for being subjected to, flow out bus for sending, send on the occasion of, be subjected to be negative value): send meritorious 25MW, send idle 25MW, can calculate tg φ=Q/P=1 so, pass through arctg=1 so, just can obtain φ=45 ° and in first quartile, if be reference voltage with Ua this moment, the phasing degree of Ia is 45 ° so, come the picture vector plot according to positive sequence, the phasing degree of Ib is 165 °, and the phasing degree of Ic is 285 °.If it is meritorious, idle send that to be subjected to situation be to send meritorious 25MW, be subjected to idle-25MW, can calculate tg φ=Q/P=-1 so, pass through arctg-1 so, just can obtain φ=135 ° or 315 °, according to meritorious, the idle situation that is subjected to of sending, the phasing degree should be at the 4th quadrant as can be seen, the phasing degree just should be 315 ° so, and is meritorious, the idle relation that is subjected to situation and quadrant of sending is referring to Fig. 1, so if be reference voltage with Ua this moment, the phasing degree of Ia is 315 ° so, come the picture vector plot according to positive sequence, the phasing degree of Ib is 75 °, and the phasing degree of Ic is 195 °.The calculating of protection CT secondary current effective value is relevant with the no-load voltage ratio in metering CT loop; if the no-load voltage ratio of two CT groups is identical, the effective value of secondary current just equate or the primary current that will measure the CT loop secondary current effective value after according to the no-load voltage ratio conversion equal.If the no-load voltage ratio difference of two CT groups, the effective value of secondary current is just unequal, and the primary current that need record measurement loop calculates the secondary current effective value in protection loop according to the no-load voltage ratio of protection loop CT.After phase angle and amplitude were determined, correct vector plot just can have been drawn out.
3, the phase place and the amplitude of each phase current of actual measurement protection CT loop:
With Ua is the phasing degree that reference voltage records Ia, Ib, Ic.With the phase voltage table record secondary current effective value (this measured value will with measure primary current that the CT loop records no-load voltage ratio according to protection loop CT, the secondary current effective value that calculates the protection loop equates).Draw out actual vector plot on this basis.
4, with the vector plot in the protection CT loop of actual measurement with according to measure correct vector plot that the CT loop drawn compare analysis, judge the correctness of this protection loop CT wiring:
The phase place of actual measurement is compared according to the correct phase that the transformer station of measuring loop, stoichiometric point or interrelate with it obtains with instrument, be easy to just judge the various mistakes of wiring.Coinciding, it is correct to be wiring, can draw various judged results according to following table;
Annotate: A ', B ', C ' are concerned definite correct phasing degree for sending according to power, A, B, the phasing degree of C for surveying.Expression is walked crosswise and is erected the value of going and equates in the grid that intersects in the form.
Example: part wiring error vector plot
6, by above-mentioned work each side winding connection error analysis of conventional transformer, judgement are finished, the staff need correct the wiring of mistake, again measure after the correction, till wiring is correct, to notice in the wiring correction process that each side CT loop extension line of conventional main transformer is an end of the same name, guarantee it is that end of the same name is drawn:
7, adopt the simultaneously-measured method of each side homophase, the correctness of analyze, each side of judgement conventional transformer differential protection being closed the phase result:
7.1 calculated equilibrium coefficient.
Formula one:
Have according to formula one:
Formula two is then arranged:
Wherein, S is the capacity of main transformer;
U is a winding primary side rated line voltage;
I is a winding primary side rated current;
Ie is a winding secondary rated current;
Nct is a winding CT no-load voltage ratio.
8, output conclusion
Last analysis result has two kinds of situations: the one, and wiring is correct, and the 2nd, wiring error.
9. the algorithm basic theories is verified and conclusion
For the judgement of each side CT circuit connection correctness of conventional transformer be based on each loop meritorious, idle send the actual conditions that are subjected to, so if determined that each loop is meritorious, idle sending be subjected to situation just can be easily, the correctness of definite CT circuit connection intuitively.After having guaranteed each side CT circuit connection correctness of conventional transformer; adopt the simultaneously-measured method of each side homophase to do the phase of closing in conventional transformer differential protecting CT loop; maximum like this each side of conventional transformer that guaranteed is measured the simultaneity of numerical value, has guaranteed that each side of conventional transformer closes facies analysis result's accuracy.
The conclusion of deriving according to algorithm of deriving with practical conditions is consistent fully with the factual error situation.
Claims (4)
1. an a kind of method of judging conventional transformer wiring correctness is characterized in that: may further comprise the steps: 1) draw the correct vector plot in this loop; Draw the vector plot of actual measurement with reference voltage; 2) export this circuit connection correctness analysis result: 3) obtain each side CT of conventional transformer differential protection and close the phase desired parameters; 4) adopt the simultaneously-measured method of each side homophase to draw the vector plot of each side CT selected item of conventional transformer differential protection loop with reference voltage; 5) according to conventional transformer and parameter thereof conventional transformer differential protecting CT loop measured value is converted; Analyze, judge and close the facies analysis result, and the output analysis result: the 5.1) coefficient of balance of each winding of calculating conventional transformer; 5.2) according to the convert current effective value of this winding of the coefficient of balance of each winding of conventional transformer; 5.3) all current phases are deducted with the measurement loop is the phase power angle of reference; 5.4) judge whether reference voltage is Ua; 5.5) if conventional transformer differential protecting CT loop is analyzed, then to carry out causing the compensation of each side primary current phase difference owing to the difference of a winding connection mode of each side of conventional transformer.
2. a kind of method of judging conventional transformer wiring correctness according to claim 1 is characterized in that: the specific implementation method of the above step 5) is:
5.1) calculate the coefficient of balance of each winding of conventional transformer;
5.2) according to the convert current effective value of this winding of the coefficient of balance of each winding of conventional transformer;
5.3) all current phases are deducted with the measurement loop is the phase power angle of reference;
5.4) judge whether reference voltage is Ua, if then direct execution in step 2.5); If not then reference voltage being converted to behind the Ua execution in step 2.5 again);
5.5) if conventional transformer differential protecting CT loop is analyzed; then to carry out causing the compensation of each side primary current phase difference, preserve parameter and execution in step 6 after converting then) owing to the difference of a winding connection mode of each side of conventional transformer.
3. a kind of method of judging conventional transformer wiring correctness according to claim 2 is characterized in that: the computing method for the coefficient of balance of conventional transformer differential protection described step 5.1) are:
5.1.1) calculate the secondary rated current of each winding;
Wherein, S is the capacity of conventional transformer; U is a winding primary side rated line voltage;
I is a winding primary side rated current; Ie is a winding secondary rated current; Nct is a winding CT no-load voltage ratio; Calculate the secondary rated current of each winding according to above-mentioned formula two;
5.1.2) one coefficient of balance establishing a rated current maximum of each winding is 1, converts the coefficient of balance of other windings;
5.1.3) coefficient of balance should be smaller or equal to 4, if having in each lateral balance coefficient greater than 4, so it are made as 4, again the coefficient of balance of other windings is changed.
4. a kind of method of judging conventional transformer wiring correctness according to claim 3 is characterized in that: the computing method of conventional transformer differential protection coefficient of balance are described step 5.2):
Become example with two circles, have according to formula two:
Wherein, Ihe is the high-pressure side rated current; Uh is the high-pressure side rated voltage; Nhct is a high-pressure side CT no-load voltage ratio; Ile is the low-pressure side rated current; Ul is the low-pressure side rated voltage; Nlct is a low-pressure side CT no-load voltage ratio; With the high-pressure side is benchmark, calculates the coefficient of balance of other windings, and promptly establishing high-pressure side coefficient of balance Kh is 1, then low-pressure side coefficient of balance Kl=(Uh * Nhct)/(Ul * Nlct); The coefficient of balance of each winding in the time of in like manner can calculating three circle changes or other situation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009103115684A CN102096008A (en) | 2009-12-15 | 2009-12-15 | Method for judging wiring correctness of conventional transformer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN2009103115684A CN102096008A (en) | 2009-12-15 | 2009-12-15 | Method for judging wiring correctness of conventional transformer |
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| CN102096008A true CN102096008A (en) | 2011-06-15 |
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| CN2009103115684A Withdrawn CN102096008A (en) | 2009-12-15 | 2009-12-15 | Method for judging wiring correctness of conventional transformer |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104730408A (en) * | 2015-03-03 | 2015-06-24 | 国家电网公司 | Method for verifying correctness of differential circuit of transformer with large capacity |
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2009
- 2009-12-15 CN CN2009103115684A patent/CN102096008A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104730408A (en) * | 2015-03-03 | 2015-06-24 | 国家电网公司 | Method for verifying correctness of differential circuit of transformer with large capacity |
| CN104730408B (en) * | 2015-03-03 | 2017-11-14 | 国家电网公司 | A kind of method for verifying high-power transformer differential circuit correctness |
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Open date: 20110615 |