CN102096013A - Single-switch differential protection CT (Current Transformer) wiring correctness analysis method of four-winding conventional transformer - Google Patents
Single-switch differential protection CT (Current Transformer) wiring correctness analysis method of four-winding conventional transformer Download PDFInfo
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- CN102096013A CN102096013A CN2009103115839A CN200910311583A CN102096013A CN 102096013 A CN102096013 A CN 102096013A CN 2009103115839 A CN2009103115839 A CN 2009103115839A CN 200910311583 A CN200910311583 A CN 200910311583A CN 102096013 A CN102096013 A CN 102096013A
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Abstract
The invention relates to a single-switch differential protection CT (Current Transformer) wiring correctness analysis method of a four-winding conventional transformer. The range of transformer differential protection comprises electrical equipment among CTs forming the transformer differential protection and leads for connecting the equipment, and the differential protection is the master protection of the transformer and is set according to a circulating current principle. The single-switch differential protection CT wiring correctness analysis method of the four-winding conventional transformer simplifies the secondary loop wiring and eliminates the electric connections of CTs at all sides, and the safe grounding of the CTs can be moved to a transformer terminal box; moreover, the reliability of an analysis result is higher than that of a traditional analysis method; and the analysis is not influenced by the aspects of subjective factors of staff, objective environment factors, and the like so as to ensure that the accuracy of the analysis result is greatly improved.
Description
Technical field
The present invention relates to a kind of four winding conventional transformer list switch differential protecting CT wiring correctness analytical approachs, whether the wiring that relates in particular to the current transformer CT of differential protection circuit is correctly carried out analysis and judgement and is provided errors present and the connection analysis method of type of error.
Background technology
Differential protection is the main protection of transformer, installs by the circulating current principle.Be mainly used to protect the various phase faults that take place on double winding or three-winding transformer winding inside and the extension line thereof, also can be used for protecting simultaneously the single-phase shorted-turn fault of transformer.Current transformer is all installed in both sides at winding transformer, and its secondary side is pressed the wiring of circulating current method, if promptly the homopolar end of both sides current transformer is all towards bus bar side, then the same polarity terminal is linked to each other, and parallel connection inserts current relay between two wiring.The electric current that flows through in relay coil is secondary current poor of both sides current transformer, that is to say that differential relay is connected on differential circuit.
Theoretically, normally operation and during external fault, the differential circuit electric current is zero.In fact owing to the characteristic of both sides current transformer can not be in full accord etc. reason, when normal operation and external short circuit, still have out-of-balance current Iumb to flow through in the differential circuit, the electric current I K that flows through relay this moment be Ik=I1-I2=Iumb require that out-of-balance current should try one's best little, can malfunction to guarantee relay.When transformer is inner when phase fault takes place, because I2 has changed direction or equal zero (non-transformer side), this is that the electric current that flows through relay is I1 and I2 sum in differential circuit, and promptly Ik=I1+I2=Iumb can make the relay action message.
The scope of transformer differential protection is to constitute electrical equipment between the current transformer of transformer differential protection and the lead that connects these equipment.Since differential protection to the protection external area error can not move, so differential protection do not need with the protected location outside adjacent element protection on working value and operation time limit, cooperatively interact, so when troubles inside the sample space, can snap action.
Differential protection is reflection protected element both sides difference between current and the protective device that moves.Differential protection is the internal short circuit fault of protection transformer, current transformer is installed in the both sides of transformer, when normal load situation or outside are short-circuited, the electric current that flows into differential relay is an out-of-balance current, under the condition of the transformation ratio that suitably chooses the both sides current transformer and the mode of connection, this out-of-balance current value is very little, and less than the action current of differential protection, so protection is failure to actuate; When transformer inside is short-circuited, flow into the action current of the electric current of relay greater than differential protection, differential protection moves in tripping operation.Since transformer first and second electric current, voltage swing difference, the phase place difference, current transformer characteristic difference, mains side has exciting current, all will cause out-of-balance current to flow through relay, must adopt corresponding measure to eliminate the influence of out-of-balance current.
(1) reduce out-of-balance current under the stable situation: the current transformer that each side of transformer differential protection is used, select the D level current transformer of transformer differential protection special use for use; When by outside maximum steady state short-circuit current, the secondary load of differential protection loop wants to satisfy the requirement of 10% error.
(2) reduce the secondary load of current transformer: in fact this be equivalent to reduce the terminal voltage of secondary side, correspondingly reduces the exciting current of current transformer.The way commonly used that reduces secondary load has: the resistance (suitably increase conductor cross-section, shorten umbilical cable length as far as possible) that reduces umbilical cable; Adopt the current transformer (the secondary rated current is lA) of light current control usefulness etc.
(3) adopt the current transformer of being with small air gap: the remanent magnetism of this current transformer core is less, and under the bigger situation of primary side current, current transformer is not easy saturated.Thereby exciting current is less, helps reducing out-of-balance current.The transient characterisitics of current transformer have also been improved simultaneously.
The secondary burden of current transformer is formed by connecting current transformer and the secondary cable of protective device, the protective relaying device of relay-set and the contact resistance of connecting line and terminal.And wherein secondary cable impedance Z L is the main part of Current Transformer Secondary burden, account for 90% and more than.The ac circuit impedance of protective relaying device is very little, and as being the microcomputer type protective device ac circuit consumption 1VA of 5A in the rated current, its impedance Z K also just is about 0.04 Europe so.And the standoff distance that the switch yard of UHV (ultra-high voltage) power plant, transformer station is installed to protection is often distant, with regard to regard to the switch yard of 220KV, the cable of current return often more than 200m, the longest 400m that reaches.As calculating with average 300m, cross-section of cable 2.5mm2 copper core, then its resistance is about 2.148 ohm, is 4mm2 as the cross-section of cable, then R=1.34 ohm.
In addition, very important factor is that the secondary burden Z of current transformer and wiring, the short-circuit-type of current transformer have much relations.Be the example explanation with two winding transformer Y0/D just now, following table has been listed the different wiring of current transformer, the secondary of current transformer burden during the different faults type.
Summary of the invention
Waste time and energy when relay protection circuit wiring error situation being judged in order to solve under the at present artificial situation, to the demanding situation of staff, the invention provides the connection analysis method in a kind of discriminatory analysis reliability height, simple, the easy to operate electric relay protection circuit safe in utilization.
Technical solution of the present invention is: the invention provides a kind of four winding conventional transformer list switch differential protecting CT wiring correctness analytical approachs, its special character is:
1) obtain conventional transformer differential protection route survey value and parameter:
Conventional transformer differential protection route survey value and parameter comprise the current effective value of each winding and phase place, conventional transformer the mode of connection, each winding CT no-load voltage ratio, each winding rated voltage, each winding power supply mode, each winding number of switches, whether pass through secondary connection adjustment (or CT secondary connection form), each winding numbering, and selected reference voltage when measuring; Because the conventional low-pressure side that becomes does not have secondary voltage, so reference voltage is not chosen as low-pressure side during measurement.
2) according to the conventional transformer parameter conventional transformer differential protection route survey value is converted, its specific implementation is:
2.1) with this winding of N phase current correction of winding or circuit or A, B, the C phase current of circuit;
2.2) coefficient of balance of each winding of calculating transformer;
2.3) according to the convert current effective value of this winding of the coefficient of balance of each winding of transformer;
2.4) all current phases are deducted the reference phase power angle that the user imports;
2.5) judge whether reference voltage is Ua, if then direct execution in step 2.6); If not then reference voltage being converted to behind the Ua execution in step 2.6 again);
2.6) mode of connection of unified conventional transformer, preserve parameter and execution in step after converting then.
When 3) revising in anglec of rotation mode, its specific implementation correction and deterministic process are: with 60 ° serves as to circulate at interval to rotate in one-period, rotates a winding at every turn, once rotates 60 °, carries out a correctness after each rotation and judges; Rotate if do not satisfy then continue, till satisfying correctness condition; If all rotating to finish successively, all windings still can not satisfy correctness condition.
4) analysis result of Sheng Chenging is: wiring is correct, wiring error maybe can't be judged.Be the output analysis result, if the result be wiring error then further output error situation) current effective value after just and the parameter of preservation compare, and generates analysis result then.When analysis result is wiring error, further export the wiring state of each winding or each phase of circuit.Wiring state according to output is corrected error situation.The wiring state of its each phase has respectively for certain winding:
A has mutually: the A phase connection is correct, A joins instead with B, A joins instead with C, A phase polarity connects instead, A joins with B, and anti-and current B phase polarity connects instead, A joins anti-with C and current C phase polarity connects instead;
B has mutually: the B phase connection is correct, B joins instead with A, B joins instead with C, B joins with A, and anti-and current A phase polarity connects instead, B phase polarity connects instead, B joins anti-with C and current C phase polarity connects instead;
C has mutually: the C phase connection is correct, C joins instead with A, C joins instead with B, C joins with A, and anti-and current A phase polarity connects instead, C joins with B, and anti-and current B phase polarity connects instead, C phase polarity connects instead.
Advantage of the present invention is:
1, differential protection has high reliability, high sensitivity.
2, simplify the secondary circuit wiring, eliminated electrically connecting of each side current transformer of transformer, the safety ground of current transformer can be moved to the mutual inductor terminal box.
3, reduced the secondary load of mutual inductor.
4, analysis result is reliable, and accuracy significantly improves.A kind of four winding conventional transformer list switch differential protecting CT wiring correctness analytical approachs provided by the present invention are carried out twice correction and are judged; can provide perfect 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.
5, simple to operate, safe and reliable.The present invention oversimplifies the analytical work of electric relay protection circuit connection, only need simply measure and can analyze and provide the result automatically, and staff's technical merit is required significantly to reduce.
Embodiment
The invention provides a kind of four winding conventional transformer list switch differential protecting CT wiring correctness analytical approachs, this method embodiment is:
1) obtain conventional transformer differential protection route survey value and parameter:
Conventional transformer differential protection route survey value and parameter comprise the current effective value of each winding and phase place, conventional transformer the mode of connection, each winding CT no-load voltage ratio, each winding rated voltage, each winding power supply mode, each winding number of switches, whether pass through secondary connection adjustment (or CT secondary connection form), each winding numbering, and selected reference voltage when measuring; Because the conventional low-pressure side that becomes does not have secondary voltage, so reference voltage is not chosen as low-pressure side during measurement.
2) according to the conventional transformer parameter conventional transformer differential protection route survey value is converted, its specific implementation is:
2.1) with this winding of N phase current correction of winding or circuit or A, B, the C phase current of circuit;
2.2) coefficient of balance of each winding of calculating transformer;
2.3) according to the convert current effective value of this winding of the coefficient of balance of each winding of transformer;
2.4) all current phases are deducted the reference phase power angle that the user imports;
2.5) judge whether reference voltage is Ua, if then direct execution in step 2.6); If not then reference voltage being converted to behind the Ua execution in step 2.6 again);
2.6) mode of connection of unified conventional transformer, preserve parameter and execution in step after converting then.
When 3) revising in anglec of rotation mode, its specific implementation correction and deterministic process are: with 60 ° serves as to circulate at interval to rotate in one-period, rotates a winding at every turn, once rotates 60 °, carries out a correctness after each rotation and judges; Rotate if do not satisfy then continue, till satisfying correctness condition; If all rotating to finish successively, all windings still can not satisfy correctness condition.
4) analysis result of Sheng Chenging is: wiring is correct, wiring error maybe can't be judged.Be the output analysis result, if the result be wiring error then further output error situation) current effective value after just and the parameter of preservation compare, and generates analysis result then.When analysis result is wiring error, further export the wiring state of each winding or each phase of circuit.Wiring state according to output is corrected error situation.The wiring state of its each phase has respectively for certain winding:
A has mutually: the A phase connection is correct, A joins instead with B, A joins instead with C, A phase polarity connects instead, A joins with B, and anti-and current B phase polarity connects instead, A joins anti-with C and current C phase polarity connects instead;
B has mutually: the B phase connection is correct, B joins instead with A, B joins instead with C, B joins with A, and anti-and current A phase polarity connects instead, B phase polarity connects instead, B joins anti-with C and current C phase polarity connects instead;
C has mutually: the C phase connection is correct, C joins instead with A, C joins instead with B, C joins with A, and anti-and current A phase polarity connects instead, C joins with B, and anti-and current B phase polarity connects instead, C phase polarity connects instead.
Claims (4)
1. winding conventional transformer list switch differential protecting CT wiring correctness analytical approach is characterized in that:
Obtain conventional transformer differential protection route survey value and parameter: conventional transformer differential protection route survey value and parameter comprise the current effective value of each winding and phase place, conventional transformer the mode of connection, each winding CT no-load voltage ratio, each winding rated voltage, each winding power supply mode, each winding number of switches, whether pass through secondary connection adjustment (or CT secondary connection form), each winding numbering, and selected reference voltage when measuring; Because the conventional low-pressure side that becomes does not have secondary voltage, so reference voltage is not chosen as low-pressure side during measurement.
2. a kind of four winding conventional transformer list switch differential protecting CT wiring correctness analytical approachs according to claim 1, it is characterized in that: according to the conventional transformer parameter conventional transformer differential protection route survey value is converted, its specific implementation is: with this winding of N phase current correction of winding or circuit or A, B, the C phase current of circuit; The coefficient of balance of each winding of calculating transformer; According to the convert current effective value of this winding of the coefficient of balance of each winding of transformer; All current phases are deducted the reference phase power angle of user's input; Judge whether reference voltage is Ua, if then direct execution in step 2.6); After then reference voltage being converted to Ua, carry out again; The mode of connection of unified conventional transformer is preserved parameter and execution in step after converting then.
3. a kind of four winding conventional transformer list switch differential protecting CT wiring correctness analytical approachs according to claim 1 and 2, it is characterized in that: when revising in anglec of rotation mode, its specific implementation correction and deterministic process are: with 60 ° is circulation rotation in one-period at interval, winding of each rotation, once rotate 60 °, carry out a correctness after each rotation and judge; Rotate if do not satisfy then continue, till satisfying correctness condition; If all rotating to finish successively, all windings still can not satisfy correctness condition.
4. a kind of four winding conventional transformer list switch differential protecting CT wiring correctness analytical approachs according to claim 3, it is characterized in that: the analysis result of generation is: wiring is correct, wiring error maybe can't be judged.Be the output analysis result, if the result be wiring error then further output error situation) current effective value after just and the parameter of preservation compare, and generates analysis result then.When analysis result is wiring error, further export the wiring state of each winding or each phase of circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009103115839A CN102096013A (en) | 2009-12-15 | 2009-12-15 | Single-switch differential protection CT (Current Transformer) wiring correctness analysis method of four-winding conventional transformer |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009103115839A CN102096013A (en) | 2009-12-15 | 2009-12-15 | Single-switch differential protection CT (Current Transformer) wiring correctness analysis method of four-winding conventional transformer |
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| CN102096013A true CN102096013A (en) | 2011-06-15 |
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| CN2009103115839A Withdrawn CN102096013A (en) | 2009-12-15 | 2009-12-15 | Single-switch differential protection CT (Current Transformer) wiring correctness analysis method of four-winding conventional transformer |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104698335A (en) * | 2013-12-06 | 2015-06-10 | 中冶天工集团有限公司 | Method for realizing systematic debugging of high-voltage transformer substation by using low-voltage electricity |
| 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 |
| CN109638777A (en) * | 2018-12-19 | 2019-04-16 | 中铁电气化局集团有限公司 | A kind of electric railway house transformer protection system |
-
2009
- 2009-12-15 CN CN2009103115839A patent/CN102096013A/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104698335A (en) * | 2013-12-06 | 2015-06-10 | 中冶天工集团有限公司 | Method for realizing systematic debugging of high-voltage transformer substation by using low-voltage electricity |
| CN104698335B (en) * | 2013-12-06 | 2018-03-16 | 中冶天工集团有限公司 | Method for realizing systematic debugging of high-voltage transformer substation by using low-voltage electricity |
| 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 |
| CN109638777A (en) * | 2018-12-19 | 2019-04-16 | 中铁电气化局集团有限公司 | A kind of electric railway house transformer protection system |
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Open date: 20110615 |