CN117031355A - Method for identifying turn-to-turn short circuit faults and phases of low-voltage windings of dry type transformer - Google Patents
Method for identifying turn-to-turn short circuit faults and phases of low-voltage windings of dry type transformer Download PDFInfo
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- G—PHYSICS
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- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/62—Testing of transformers
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/72—Testing of electric windings
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Abstract
A method for identifying turn-to-turn short circuit faults and phases of a low-voltage winding of a dry-type transformer belongs to the technical field of transformer safe operation. Acquiring a current and voltage signal; calculating a voltage and current imbalance difference value; calculating the total winding loss change rate of the dry-type transformer and the power loss change rate of each phase winding; judging whether the voltage and current imbalance difference is zero or not; judging whether a fault judging condition is met; the dry type transformer continues to run normally or gives out an early warning instruction, and gives out a tripping instruction at the same time of giving out the early warning instruction. The application can accurately monitor the single turn-to-turn short circuit fault of the low-voltage winding of the dry-type transformer, can sense the insulation degradation condition of the winding of the dry-type transformer in advance, overcomes the influence of inherent asymmetry and unbalanced operation of the dry-type transformer on the turn-to-turn short circuit fault detection error, effectively prevents the burning of the dry-type transformer, and improves the operation and maintenance efficiency.
Description
Technical Field
A method for identifying turn-to-turn short circuit faults and phases of a low-voltage winding of a dry-type transformer belongs to the technical field of transformer safe operation.
Background
The dry transformer has the characteristics of simple maintenance, low loss, oil-free performance, strong short circuit resistance and the like, is widely applied to urban power supply systems, and the safety and stability of operation of the dry transformer directly influence the power supply reliability. The winding insulation burnout accident is caused by the fact that the slight turn-to-turn short circuit faults of the dry-type transformer winding are not easy to detect and are extremely easy to rapidly evolve into serious multi-turn short circuit faults, so that the safe operation of the power distribution network is directly threatened. As disclosed in chinese patent application CN112731211a, a method for identifying turn-to-turn short circuit faults and phases of a low-voltage winding of a grounding transformer is disclosed, by which the low-voltage winding turn-to-turn short circuit faults and phases of the grounding transformer are accurately monitored when single-turn-to-turn short circuit faults occur in the low-voltage winding of the grounding transformer, and a fault phase can be judged, and a tripping command can be timely sent out, so that the burning of the grounding transformer is effectively prevented, and the operation and maintenance efficiency is improved. The application of China patent application CN112968423A discloses a method for protecting the turn-to-turn short circuit fault of a low-voltage winding of an over-current protection of a grounding transformer, which can reach an action fixed value when the single-turn-to-turn short circuit fault of the low-voltage winding of the grounding transformer occurs by changing the fixed value of the over-current protection action of the high-voltage side of the grounding transformer into 1.5 times of the rated current IN2 of the high-voltage winding calculated by taking the capacity of the low-voltage side as a reference, and timely sends out a tripping command, thereby effectively preventing the burning of the grounding transformer.
At present, current differential protection and overcurrent protection are mostly adopted for relay protection of a dry-type transformer in actual engineering. Although the current change of the short-circuit turns is extremely large when the winding turn-to-turn short-circuit fault occurs, the electromagnetic parameters of the winding short-circuit turns cannot be actually measured due to the limitation of the inherent structure of the winding, and the main loop phase voltage and the phase current change caused by the current change are weak, so that the overcurrent protection and the differential protection actions of the dry-type transformer cannot be performed, and the serious damage and even explosion and fire of the dry-type transformer can be caused.
Therefore, early slight turn-to-turn short circuit faults of the dry-type transformer windings can be perceived in advance and timely identified, and the problems of hot spots and difficulties in the state detection technology of the dry-type transformer are always the problems.
Disclosure of Invention
The application aims to solve the technical problems that: the method for identifying the turn-to-turn short circuit faults of the low-voltage winding of the dry-type transformer and the phase thereof overcomes the defects of the prior art, accurately monitors the single-turn-to-turn short circuit faults of the low-voltage winding of the dry-type transformer, can judge the fault phase, and effectively prevents the dry-type transformer from being burnt.
The technical scheme adopted for solving the technical problems is as follows: the method for identifying the turn-to-turn short circuit fault and the phase of the low-voltage winding of the dry-type transformer is characterized by comprising the following steps of: the method comprises the following steps:
step a, obtaining a current value I of three phases of a low-voltage winding of a dry-type transformer through a current acquisition system a 、I b 、I c Current value I of high winding three phase A 、I B 、I C The voltage value U of the three phases of the low-voltage winding of the dry-type transformer is obtained through a voltage acquisition system a 、U b 、U c Voltage value U of three phases of high-voltage winding A 、U B 、U C ；
Step b, the current collecting system calculates the current unbalance degree under the normal working condition as a reference value, the voltage collecting system calculates the voltage unbalance degree under the normal working condition as a reference value, the current collecting system calculates the current unbalance degree in a real-time state as a named value, the voltage collecting system calculates the voltage unbalance degree in the real-time state as a named value, and meanwhile, the difference value between the per unit value of the current unbalance degree and the per unit value of the voltage unbalance degree is calculated;
step c, calculating the total winding power loss change rate of the dry-type transformer and the winding loss change rate of each phase through a voltage and current acquisition system;
step d, judging whether the voltage and current unbalance difference is zero, if so, executing step k, and if not, executing step e;
step e, judging whether the dry-type transformer meets the judging condition that the turn-to-turn short circuit fault occurs in the a-phase winding, if so, executing the step f, and if not, executing the step g;
step f, a phase a winding in a low-voltage winding of the dry-type transformer has turn-to-turn short circuit fault, and the step m is executed;
step g, judging whether the dry-type transformer meets the judging condition that the turn-to-turn short circuit fault occurs in the b-phase winding, if so, executing the step h, and if not, executing the step i;
step h, a turn-to-turn short circuit fault occurs in a b-phase winding in a low-voltage winding of the dry-type transformer, and the step m is executed;
step i, judging whether the dry-type transformer meets the judging condition that the turn-to-turn short circuit fault occurs in the c-phase winding, if so, executing the step j, and if not, executing the step l;
step j, a turn-to-turn short circuit fault occurs in a c-phase winding in a low-voltage winding of the dry-type transformer, and the step m is executed;
step k, the dry type transformer operates normally;
step l, the insulation of the low-voltage winding of the dry-type transformer is damaged, and an early warning instruction is sent out and displayed;
and m, a turn-to-turn short circuit fault occurs in the low-voltage winding of the dry-type transformer, and a tripping instruction is sent out and displayed.
Preferably, the method for calculating the per unit value of the current unbalance degree in the step b is as follows:
wherein U is A 、U B 、U C Representative of instantaneous voltage values measured by three-phase current transformer of dry matter transformer, U AN 、U BN 、U CN The voltage value measured by the three-phase current transformer under the normal working condition of the dry matter transformer is represented, and a represents the imaginary part.
Preferably, the method for calculating the per unit value of the voltage unbalance in the step b is as follows:
wherein I is A 、I B 、I C Representing the instantaneous value of current measured by three-phase current transformer of dry matter transformer, I AN 、I BN 、I CN The current value measured by the three-phase current transformer under the normal working condition of the dry matter transformer is represented, and a represents the imaginary part.
Preferably, the method further comprises the step of calculating a voltage and current imbalance difference value of the dry-type transformer, wherein the calculation method comprises the following steps:
ξ＝|CVUF * -CCUF * |；
wherein U is 1 、U 2 Respectively are provided withThe voltage of the primary side and the secondary side; i 1 、I 2 The current of the primary side and the secondary side respectively;the power factors of the primary side and the secondary side are respectively; Δp is the actual power lost; ΔP N Active power for theoretical loss; CCUF (Central control Unit) * The voltage unbalance degree per unit value of the dry-type transformer; CVUF * Is the per unit value of the voltage unbalance of the dry-type transformer.
Preferably, the calculation method of the total winding power loss change rate of the dry-type transformer in the step c is as follows:
wherein U is 1 、U 2 The voltages of the primary side and the secondary side respectively; i 1 、I 2 The current of the primary side and the secondary side respectively;the power factors of the primary side and the secondary side are respectively; Δp is the actual power lost; ΔP N Is the active power of theoretical loss, and eta is the winding loss change rate.
Preferably, in the step e, the judging condition that the turn-to-turn short circuit fault occurs in the a-phase winding is as follows: the voltage unbalance per unit value and the current unbalance per unit value of the dry type transformer are not zero; the total winding loss change rate of the dry-type transformer is larger than 20%, and the a-phase winding loss change rate is larger than the b-phase winding loss change rate and the c-phase winding loss change rate.
Preferably, in the step g, the judging condition of the turn-to-turn short circuit fault of the b-phase winding is as follows: the voltage unbalance per unit value and the current unbalance per unit value of the dry type transformer are not zero; the total winding loss change rate of the dry-type transformer is larger than 20%, and the b phase is larger than the a phase and c phase winding loss change rate.
Preferably, in the step i, the judging condition that the turn-to-turn short circuit fault occurs in the c-phase winding is as follows: the voltage unbalance per unit value and the current unbalance per unit value of the dry type transformer are not zero; the total winding loss change rate of the dry-type transformer is larger than 20%, and the c-phase winding loss change rate is larger than the a-phase winding loss change rate and the b-phase winding loss change rate.
Preferably, the current collection system comprises a low-voltage winding current sensor, a high-voltage winding current sensor, a signal collection unit, a logic analysis unit, a communication unit and a human-computer interface, wherein the low-voltage winding current sensor and the high-voltage winding current sensor are respectively arranged in the low-voltage winding and the high-voltage winding of the dry-type transformer, the output end of the current sensor is connected with the signal input end of the signal collection unit, the output end of the signal collection unit is connected with the input end of the logic analysis unit, and the output end of the logic analysis module is connected with the human-computer interface through the communication unit.
Preferably, the voltage acquisition system comprises a low-voltage winding voltage sensor, a high-voltage winding voltage sensor, a signal acquisition unit, a logic analysis unit, a communication unit and a human-computer interface, wherein the low-voltage winding voltage sensor and the high-voltage winding voltage sensor are respectively arranged in the low-voltage winding and the high-voltage winding of the dry-type transformer, the output end of the voltage sensor is connected with the signal input end of the signal acquisition unit, the output end of the signal acquisition unit is connected with the input end of the logic analysis unit, and the output end of the logic analysis module is connected with the human-computer interface through the communication unit.
Compared with the prior art, the application has the following beneficial effects:
the method for identifying the turn-to-turn short circuit faults and the phases of the low-voltage winding of the dry-type transformer is used for accurately monitoring the single-turn-to-turn short circuit faults of the low-voltage winding of the dry-type transformer, judging the fault phases, sensing the insulation degradation condition of the winding of the dry-type transformer in advance, overcoming the influence of inherent asymmetry and unbalanced operation of the dry-type transformer on the detection errors of the turn-to-turn short circuit faults, effectively preventing the dry-type transformer from being burnt, and improving the operation and maintenance efficiency.
Drawings
FIG. 1 is a logic block diagram of a method for identifying turn-to-turn short circuit faults and phases of a low-voltage winding of a dry-type transformer;
fig. 2 is a hardware circuit connection diagram of a dry-type transformer low-voltage winding turn-to-turn short circuit fault and a phase identification method.
Detailed Description
The present application will be further described with reference to specific embodiments, however, it will be understood by those skilled in the art that the detailed description is given herein for the purpose of illustration only, and the application is not necessarily limited to the details of these embodiments, but may be practiced otherwise than as specifically described herein for the purpose of illustration only and as yet within the scope of the appended claims.
As shown in fig. 1-2: a method for identifying turn-to-turn short circuit faults and phases of a low-voltage winding of a dry-type transformer comprises the following steps:
step a, obtaining a current value I of three phases of a low-voltage winding of a dry-type transformer through a current acquisition system a 、I b 、I c Current value I of high winding three phase A 、I B 、I C The voltage value U of the three phases of the low-voltage winding of the dry-type transformer is obtained through a voltage acquisition system a 、U b 、U c Voltage value U of three phases of high-voltage winding A 、U B 、U C 。
The system comprises a current acquisition system and a voltage acquisition system, wherein the current acquisition system comprises a low-voltage winding current sensor, a high-voltage winding current sensor, a signal acquisition unit, a logic analysis unit, a communication unit and a human-computer interface, the low-voltage winding current sensor and the high-voltage winding current sensor are respectively arranged in a low-voltage winding and a high-voltage winding of the dry-type transformer, the output end of the current sensor is connected with the signal input end of the signal acquisition unit, the output end of the signal acquisition unit is connected with the input end of the logic analysis unit, and the output end of the logic analysis module is connected with the human-computer interface through the communication unit. The voltage acquisition system comprises a low-voltage winding voltage sensor, a high-voltage winding voltage sensor, a signal acquisition unit, a logic analysis unit, a communication unit and a human-computer interface, wherein the low-voltage winding voltage sensor and the high-voltage winding voltage sensor are respectively arranged in the low-voltage winding and the high-voltage winding of the dry-type transformer, the output end of the voltage sensor is connected with the signal input end of the signal acquisition unit, the output end of the signal acquisition unit is connected with the input end of the logic analysis unit, and the output end of the logic analysis module is connected with the human-computer interface through the communication unit. The current acquisition system and the voltage acquisition system share a signal acquisition unit, a logic analysis unit, a communication unit and a human-computer interface.
Obtaining a current value I of three phases of a low-voltage winding of the dry-type transformer through a low-voltage winding current and voltage sensor a 、I b 、I c Voltage value U of three phases of low-voltage winding a 、U b 、U c The current value I of three phases of the dry-type transformer Gao Raozu is obtained by a high-voltage winding current and voltage sensor A 、I B 、I C Voltage value U of three phases of high-voltage winding A 、U B 、U C 。
The output ends of the current sensor and the voltage sensor are connected with the signal input end of the signal acquisition unit, the output end of the signal acquisition unit is connected with the input end of the logic analysis unit, the signal acquisition module sends the current signals sent by the low-voltage winding voltage and the current sensor and the high-voltage winding voltage and the current sensor to the logic analysis module for judgment, and the logic analysis module sends the judgment result to the human-computer interface through the communication unit for display by the human-computer interface.
And b, the current collecting system calculates the current unbalance degree under the normal working condition as a reference value, the voltage collecting system calculates the voltage unbalance degree under the normal working condition as a reference value, the current collecting system calculates the current unbalance degree in a real-time state as a named value, the voltage collecting system calculates the voltage unbalance degree in the real-time state as a named value, and meanwhile, the difference value between the per unit value of the current unbalance degree and the per unit value of the voltage unbalance degree is calculated.
The logic analysis unit calculates the per unit value of the voltage unbalance degree of the dry-type transformer according to the data sent by the signal acquisition module, and the calculation formula is as follows:
wherein U is A 、U B 、U C Representative of instantaneous voltage values measured by three-phase current transformer of dry matter transformer, U AN 、U BN 、U CN The voltage value measured by the three-phase current transformer under the normal working condition of the dry matter transformer is represented, and a represents the imaginary part.
The per unit value of the voltage unbalance of the dry-type transformer is calculated, and the calculation formula is as follows:
wherein I is A 、I B 、I C Representing the instantaneous value of current measured by three-phase current transformer of dry matter transformer, I AN 、I BN 、I CN The current value measured by the three-phase current transformer under the normal working condition of the dry matter transformer is represented, and a represents the imaginary part.
The voltage and current imbalance difference value of the dry-type transformer is calculated, and the calculation formula is as follows:
ξ＝|CVUF * -CCUF * |。
and c, calculating the total winding power loss change rate of the dry-type transformer and the winding loss change rate of each phase through a voltage and current acquisition system.
The total winding loss change rate of the dry matter transformer and the power loss change rate of each phase winding are calculated according to the following calculation formula:
wherein U is 1 、U 2 The voltages of the primary side and the secondary side respectively; i 1 、I 2 The current of the primary side and the secondary side respectively;the power factors of the primary side and the secondary side are respectively; Δp is the actual power lost; ΔP N Active power of theoretical loss, eta is the change rate of winding loss
And d, judging whether the voltage and current unbalance difference is zero, if so, executing the step k, and if not, executing the step e.
And e, judging whether the dry-type transformer meets the judging condition that the turn-to-turn short circuit fault occurs in the a-phase winding, if so, executing the step f, and if not, executing the step g.
The logic analysis module judges that the a-phase winding has the judging condition of turn-to-turn short circuit fault as follows: the voltage unbalance per unit value and the current unbalance per unit value of the dry type transformer are not zero; the total winding loss change rate of the dry-type transformer is larger than 20%, and the a-phase winding loss change rate is larger than the b-phase winding loss change rate and the c-phase winding loss change rate.
And f, carrying out step m when a turn-to-turn short circuit fault occurs in an a-phase winding in the low-voltage winding of the dry-type transformer.
And g, judging whether the dry-type transformer meets the judging condition that the turn-to-turn short circuit fault occurs in the b-phase winding, if so, executing the step h, and if not, executing the step i.
The judgment conditions for judging that the turn-to-turn short circuit fault occurs in the b-phase winding by the logic analysis module are as follows: the voltage unbalance per unit value and the current unbalance per unit value of the dry type transformer are not zero; the total winding loss change rate of the dry-type transformer is larger than 20%, and the b phase is larger than the a phase and c phase winding loss change rate.
And h, carrying out step m when a turn-to-turn short circuit fault occurs in a b-phase winding in the low-voltage winding of the dry-type transformer.
And step i, judging whether the dry-type transformer meets the judging condition that the turn-to-turn short circuit fault occurs in the c-phase winding, if so, executing the step j, and if not, executing the step l.
The logic analysis module judges that the judging condition of the turn-to-turn short circuit fault of the c-phase winding is as follows: the voltage unbalance per unit value and the current unbalance per unit value of the dry type transformer are not zero; the total winding loss change rate of the dry-type transformer is larger than 20%, and the c-phase winding loss change rate is larger than the a-phase winding loss change rate and the b-phase winding loss change rate.
And j, carrying out step m when a turn-to-turn short circuit fault occurs in a c-phase winding in the low-voltage winding of the dry-type transformer.
And step k, the dry type transformer operates normally.
And step l, the insulation of the low-voltage winding of the dry-type transformer is damaged, and an early warning instruction is sent out and displayed.
The logic analysis module judges that the low-voltage winding of the dry-type transformer has turn-to-turn short circuit fault, sends out an early warning instruction, transmits a judging result through the communication module, and displays the judging result on a human-computer interface.
And m, a turn-to-turn short circuit fault occurs in the low-voltage winding of the dry-type transformer, and a tripping instruction is sent out and displayed.
The logic analysis module judges that the low-voltage winding of the dry-type transformer has turn-to-turn short circuit fault, sends out a tripping instruction, transmits a judging result through the communication module, and displays the judging result on a human-computer interface.
The above description is only a preferred embodiment of the present application, and is not intended to limit the application in any way, and any person skilled in the art may make modifications or alterations to the disclosed technical content to the equivalent embodiments. However, any simple modification, equivalent variation and variation of the above embodiments according to the technical substance of the present application still fall within the protection scope of the technical solution of the present application.
Claims (10)
1. A method for identifying turn-to-turn short circuit faults and phases of a low-voltage winding of a dry-type transformer is characterized by comprising the following steps of: the method comprises the following steps:
step a, obtaining a current value I of three phases of a low-voltage winding of a dry-type transformer through a current acquisition system a 、I b 、I c Current value I of high winding three phase A 、I B 、I C The voltage value U of the three phases of the low-voltage winding of the dry-type transformer is obtained through a voltage acquisition system a 、U b 、U c Voltage value U of three phases of high-voltage winding A 、U B 、U C ；
Step b, the current collecting system calculates the current unbalance degree under the normal working condition as a reference value, the voltage collecting system calculates the voltage unbalance degree under the normal working condition as a reference value, the current collecting system calculates the current unbalance degree in a real-time state as a named value, the voltage collecting system calculates the voltage unbalance degree in the real-time state as a named value, and meanwhile, the difference value between the per unit value of the current unbalance degree and the per unit value of the voltage unbalance degree is calculated;
step c, calculating the total winding power loss change rate of the dry-type transformer and the winding loss change rate of each phase through a voltage and current acquisition system;
step d, judging whether the voltage and current unbalance difference is zero, if so, executing step k, and if not, executing step e;
step e, judging whether the dry-type transformer meets the judging condition that the turn-to-turn short circuit fault occurs in the a-phase winding, if so, executing the step f, and if not, executing the step g;
step f, a phase a winding in a low-voltage winding of the dry-type transformer has turn-to-turn short circuit fault, and the step m is executed;
step g, judging whether the dry-type transformer meets the judging condition that the turn-to-turn short circuit fault occurs in the b-phase winding, if so, executing the step h, and if not, executing the step i;
step h, a turn-to-turn short circuit fault occurs in a b-phase winding in a low-voltage winding of the dry-type transformer, and the step m is executed;
step i, judging whether the dry-type transformer meets the judging condition that the turn-to-turn short circuit fault occurs in the c-phase winding, if so, executing the step j, and if not, executing the step l;
step j, a turn-to-turn short circuit fault occurs in a c-phase winding in a low-voltage winding of the dry-type transformer, and the step m is executed;
step k, the dry type transformer operates normally;
step l, the insulation of the low-voltage winding of the dry-type transformer is damaged, and an early warning instruction is sent out and displayed;
and m, a turn-to-turn short circuit fault occurs in the low-voltage winding of the dry-type transformer, and a tripping instruction is sent out and displayed.
2. The method for identifying turn-to-turn short circuit faults and phases of low-voltage windings of dry transformers according to claim 1, wherein the method comprises the following steps: the method for calculating the per unit value of the current unbalance degree in the step b is as follows:
wherein U is A 、U B 、U C Representative of instantaneous voltage values measured by three-phase current transformer of dry matter transformer, U AN 、U BN 、U CN The voltage value measured by the three-phase current transformer under the normal working condition of the dry matter transformer is represented, and a represents the imaginary part.
3. The method for identifying turn-to-turn short circuit faults and phases of low-voltage windings of dry transformers according to claim 1, wherein the method comprises the following steps: the method for calculating the per unit value of the voltage unbalance degree in the step b is as follows:
wherein I is A 、I B 、I C Representing the instantaneous value of current measured by three-phase current transformer of dry matter transformer, I AN 、I BN 、I CN The current value measured by the three-phase current transformer under the normal working condition of the dry matter transformer is represented, and a represents the imaginary part.
4. The method for identifying turn-to-turn short circuit faults and phases of low-voltage windings of dry transformers according to claim 1, wherein the method comprises the following steps: the method also comprises the steps of calculating the voltage and current imbalance difference value of the dry-type transformer, wherein the calculation method comprises the following steps:
ξ＝|CVUF * -CCUF * |；
wherein, CCUF * The voltage unbalance degree per unit value of the dry-type transformer; CVUF * Is the per unit value of the voltage unbalance of the dry-type transformer.
5. The method for identifying turn-to-turn short circuit faults and phases of low-voltage windings of dry transformers according to claim 1, wherein the method comprises the following steps: the calculation method of the total winding power loss change rate of the dry-type transformer in the step c is as follows:
wherein U is 1 、U 2 The voltages of the primary side and the secondary side respectively; i 1 、I 2 The current of the primary side and the secondary side respectively;the power factors of the primary side and the secondary side are respectively; Δp is the actual power lost; ΔP N Is the active power of theoretical loss, and eta is the winding loss change rate.
6. The method for identifying turn-to-turn short circuit faults and phases of low-voltage windings of dry transformers according to claim 1, wherein the method comprises the following steps: in the step e, the judging condition of the turn-to-turn short circuit fault of the a-phase winding is as follows: the voltage unbalance per unit value and the current unbalance per unit value of the dry type transformer are not zero; the total winding loss change rate of the dry-type transformer is larger than 20%, and the a-phase winding loss change rate is larger than the b-phase winding loss change rate and the c-phase winding loss change rate.
7. The method for identifying turn-to-turn short circuit faults and phases of low-voltage windings of dry transformers according to claim 1, wherein the method comprises the following steps: in the step g, the judging condition of the turn-to-turn short circuit fault of the b-phase winding is as follows: the voltage unbalance per unit value and the current unbalance per unit value of the dry type transformer are not zero; the total winding loss change rate of the dry-type transformer is larger than 20%, and the b phase is larger than the a phase and c phase winding loss change rate.
8. The method for identifying turn-to-turn short circuit faults and phases of low-voltage windings of dry transformers according to claim 1, wherein the method comprises the following steps: in the step i, the judging condition of the turn-to-turn short circuit fault of the c-phase winding is as follows: the voltage unbalance per unit value and the current unbalance per unit value of the dry type transformer are not zero; the total winding loss change rate of the dry-type transformer is larger than 20%, and the c-phase winding loss change rate is larger than the a-phase winding loss change rate and the b-phase winding loss change rate.
9. The method for identifying turn-to-turn short circuit faults and phases of low-voltage windings of dry transformers according to claim 1, wherein the method comprises the following steps: the current acquisition system comprises a low-voltage winding current sensor, a high-voltage winding current sensor, a signal acquisition unit, a logic analysis unit, a communication unit and a human-computer interface, wherein the low-voltage winding current sensor and the high-voltage winding current sensor are respectively arranged in a low-voltage winding and a high-voltage winding of the dry-type transformer, the output end of the current sensor is connected with the signal input end of the signal acquisition unit, the output end of the signal acquisition unit is connected with the input end of the logic analysis unit, and the output end of the logic analysis module is connected with the human-computer interface through the communication unit.
10. The method for identifying turn-to-turn short circuit faults and phases of low-voltage windings of dry transformers according to claim 1, wherein the method comprises the following steps: the voltage acquisition system comprises a low-voltage winding voltage sensor, a high-voltage winding voltage sensor, a signal acquisition unit, a logic analysis unit, a communication unit and a human-computer interface, wherein the low-voltage winding voltage sensor and the high-voltage winding voltage sensor are respectively arranged in a low-voltage winding and a high-voltage winding of the dry-type transformer, the output end of the voltage sensor is connected with the signal input end of the signal acquisition unit, the output end of the signal acquisition unit is connected with the input end of the logic analysis unit, and the output end of the logic analysis module is connected with the human-computer interface through the communication unit.
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| CN202311012454.6A CN117031355A (en) | 2023-08-11 | 2023-08-11 | Method for identifying turn-to-turn short circuit faults and phases of low-voltage windings of dry type transformer |
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