CN108152659B - Method for judging turn-to-turn insulation short circuit of electromagnetic voltage transformer - Google Patents

Abstract

The invention provides a method for judging the inter-turn insulation short circuit of an electromagnetic voltage transformer, which is suitable for the electromagnetic voltage transformer for single-phase use or the combination of multiple single-phase electromagnetic voltage transformers in a V-V shape for three-phase use , First pressurize and measure two adjacent electromagnetic voltage transformers. When the voltmeter indicates a large value, it means that one electromagnetic voltage transformer has poor inter-turn insulation, and the voltage regulator should be reduced to zero in time. Repeat the test with another unpressurized electromagnetic voltage transformer and any electromagnetic voltage transformer with overvoltage, and make judgments according to different situations. The present invention can realize the judgment of the problem only through the combination of simple elements and simple operations, is easy to use, and helps to improve the work efficiency.

Description

A method for judging inter-turn insulation short circuit of electromagnetic voltage transformer

technical field

The invention belongs to the technical field of power system safety protection methods, and in particular relates to a method for judging the inter-turn insulation short circuit of an electromagnetic voltage transformer.

technical background

At present, when 10kV, 35kV, 110kV, and 220kV electromagnetic voltage has abnormal voltage, in order to ensure the safety of the power system and prevent the accident from expanding, the electromagnetic voltage transformer is generally taken out of operation, pending inspection by professional test personnel.

When the electromagnetic voltage transformer runs for a long time, the temperature will naturally rise, and when the insulation between turns is poor, the insulation will also drop, forming a short circuit between turns, resulting in abnormal monitoring voltage. When the test personnel arrived at the work site for testing, the temperature of the electromagnetic voltage transformer had dropped and the inter-turn insulation had recovered. Because the test voltage provided by the transformer ratio bridge tester is relatively low, it is prone to misjudgment when measuring the electromagnetic voltage transformer whose inter-turn insulation has recovered. It often occurs that the power transmission is normal at that time, and the monitoring voltage is abnormal again after a time.

The invention with the patent number of 201710267297.1 discloses an electromagnetic voltage transformer inter-turn short circuit detection device and method. The detection device includes a high-frequency low-voltage steep pulse generation module, a high-speed acquisition module and a host computer with built-in analysis software; the The high-frequency low-voltage steep pulse generation module is used to generate nanosecond steep pulses, and inject steep pulse signals into the windings of the electromagnetic voltage transformer under test; the high-speed acquisition module is used for collecting the electromagnetic voltage transformer windings passing through Then, it contains the characteristic waveform of the winding short-circuit fault, and transmits it to the upper computer after preprocessing and storage; the upper computer analyzes and processes the received characteristic waveform by the repetitive pulse method, so as to obtain the electromagnetic voltage transformer under test. Short circuit fault characteristics of windings. The invention is used to detect the early inter-turn faults of the voltage transformer windings, which can locate and quantitatively compare the inter-turn insulation conditions, avoids the further expansion of the faults, and provides a reliable guarantee for the safe and stable operation of the power system.

The invention with the patent number of 201410039668.7 discloses an on-line identification method for the inter-turn short circuit of the voltage transformer at the generator terminal. Calculate the fundamental RMS value of each zero-sequence voltage separately; use the injection-type stator grounding protection principle to calculate the insulation resistance value of the stator winding to ground; when the fundamental RMS value of the zero-sequence voltage at the neutral point of the generator is greater than the stator grounding protection and the fundamental rms value of the zero-sequence voltage on the high-voltage side of the main transformer and the fundamental rms value of the zero-sequence voltage on the low-voltage side of the factory transformer are both lower than the set value, and the stator winding is insulated from the ground If the resistance value does not decrease, it is judged that the voltage transformer at the generator terminal is short-circuited between turns. After a delay, an alarm is issued, and the sensitive section of the stator grounding protection of the fundamental wave zero-sequence voltage is blocked. The inventive method can accurately judge the PT inter-turn short-circuit fault at the generator end, effectively prevent the malfunction of the stator grounding protection in this situation, and greatly shorten the troubleshooting time.

However, the above methods all need to configure a large number of detection electronic components and intelligent processing modules, which are expensive and easy to damage, and the use and maintenance costs are high, which is not conducive to quick and easy judgment under harsh or simple working conditions. Therefore, There is a need for a simple, convenient and easy-to-implement method for judging the short-circuit of the voltage transformer turn-to-turn insulation.

SUMMARY OF THE INVENTION

The invention provides a method for judging the inter-turn insulation short circuit of an electromagnetic voltage transformer. The problem can be judged only through simple components and simple operations, and it is easy to use and helps to improve work efficiency.

In order to solve the above technical problems, the present invention provides a method for judging the inter-turn insulation short circuit of an electromagnetic voltage transformer, comprising the following steps:

1) Select the detection device for judging the inter-turn insulation short circuit of the electromagnetic voltage transformer, including one AC voltage regulator and one AC voltmeter;

2) Taking the three adjacent electromagnetic voltage transformers to be inspected as an example, there is no fault or there is only one fault, and the three voltage transformers are defined as group A, group B, and group C respectively, and the The corresponding windings of the secondary side of group A and group B are connected in parallel respectively;

3) Connect the AC ammeter in parallel between the high-voltage windings of Group A and Group B, and slowly pressurize the parallel terminals of the secondary side of Group A and Group B through the AC voltage regulator, and observe the voltage value of the AC ammeter;

4) When the indication value of the AC ammeter does not increase significantly with the slow pressurization of the AC voltage regulator, and the indication value remains small, it proves that both groups A and B are fault-free electromagnetic type. voltage transformer;

5) Connect the AC ammeter in parallel between the high-voltage windings of Group B and Group C, and slowly pressurize the parallel terminals of the secondary side of Group B and Group C through the AC voltage regulator, and observe the voltage value of the AC ammeter;

6) When the indication value of the AC ammeter does not increase significantly with the slow pressurization of the AC voltage regulator, and the indication value remains small, it proves that groups A, B, and C are all fault-free. The electromagnetic voltage transformer of , the inspection is over;

7) After performing step 3), the indication value of the AC ammeter increases greatly with the slow pressurization of the AC voltage regulator, and finally maintains a large indication value, it proves that there is one meter between group A and group B. The electromagnetic voltage transformer has poor inter-turn insulation. At this time, reduce the voltage regulator to zero in time, and repeat step 5);

8) When the indication value of the AC ammeter increases greatly with the slow pressurization of the AC voltage regulator, and finally maintains a large indication value, it proves that the electromagnetic voltage transformer of group B has poor inter-turn insulation. When the voltage regulator is lowered to zero in time, the inspection is over;

9) After performing step 7), the indication value of the AC ammeter does not increase significantly with the slow pressure of the AC voltage regulator, and when the indication value remains small, it proves that the electromagnetic voltage mutual inductance of group A There is poor insulation between turns in the regulator, at this time, reduce the voltage regulator to zero in time, and the inspection is over;

10) After performing step 5), the indication value of the AC ammeter increases greatly with the slow pressurization of the AC voltage regulator, and finally maintains a large indication value, which proves that the electromagnetic voltage transformer of group C exists. The insulation between turns is poor, at this time, reduce the voltage regulator to zero in time, and the inspection is over;

11) After performing step 6), the next group of three adjacent electromagnetic voltage transformers can be coded according to the method from step 2) to step 10), until the faulty electromagnetic voltage transformer is detected.

Further, the AC voltage regulator is preferably a 220V AC voltage regulator.

Further, the test voltage of the AC voltage regulator does not exceed 60V.

Further, the AC voltmeter is preferably a 750V AC voltmeter.

The electromagnetic induction voltage transformer in the present invention has the same working principle as that of the transformer, and the basic structure is also the iron core and the primary side and secondary side windings. The characteristic is that the capacity is small and relatively constant, and it is close to the no-load state during normal operation. The impedance of the voltage transformer itself is very small. Once a short circuit occurs on the secondary side, the current will increase sharply and the coil will be burned. For this reason, a fuse is connected to the primary side of the voltage transformer, and the secondary side is reliably grounded, so as to avoid personal and equipment accidents caused by high ground potential on the secondary side when the insulation of the primary side and the secondary side is damaged. .

The method of the invention is especially suitable for the single-phase use of electromagnetic voltage transformers or the combination of multiple single-phase electromagnetic voltage transformers in the form of V-V for three-phase use. When the electromagnetic voltage transformer fails, resulting in an inter-turn short circuit, and the monitoring voltage is abnormal, the system will quickly alarm and trip. Therefore, the probability of two or more single-phase electromagnetic voltage transformer failures occurring at the same time is small. Therefore, the premise of the application of the present invention is that there is no fault in the electromagnetic voltage transformers or there is only one fault, which can meet the fault judgment in most cases, and the three adjacent electromagnetic voltage transformers are one The group is considered to be used as a three-phase voltage transformer, mostly for the connection of three single-phase voltage transformers.

The beneficial effect of the present invention is that the present invention can be used as a common detection device, through simple detection steps, to quickly and accurately determine whether there is an inter-turn short circuit in the electromagnetic voltage transformer, that is, when any two electromagnetic voltage transformers are pressurized twice , and then use the method of parallel voltmeter to judge whether the electromagnetic voltage transformer has poor inter-turn insulation. The disclosure of this simple and practical method is beneficial to improve work efficiency, achieve the purpose of accurately judging faulty electromagnetic voltage transformers, and is especially suitable for complex and harsh working conditions, and is particularly easy to implement and practical.

Description of drawings

The technical solutions in the embodiments of the present invention will be described below with reference to the accompanying drawings:

Fig. 1 is the detection wiring diagram of the detection device of the present invention.

FIG. 2 is a schematic diagram of judgment in Embodiment 1 of the present invention.

Detailed ways

Example 1

As shown in Figure 1 and Figure 2, according to the common sense of the actual working conditions, take the three adjacent electromagnetic voltage transformers to be inspected without fault or with only one fault as an example. The transformers are defined as group A, group B, and group C respectively. Select a 220V AC voltage regulator and a 750V AC voltmeter, and assemble the detection device for judging the inter-turn insulation short circuit of the electromagnetic voltage transformer according to Figure 1. The specific judgment operations are divided into several types. Judgment of the situation:

Judgment 1: Connect the corresponding windings of the secondary sides of Group A and Group B in parallel, connect the AC ammeter in parallel between the high-voltage windings of Group A and Group B, and connect the secondary sides of Group A and Group B in parallel through the AC voltage regulator. Slowly pressurize the terminal and observe the voltage value of the AC ammeter; when the indicated value of the AC ammeter does not increase significantly with the slow pressurization of the AC voltage regulator, and keeps the indicated value small, it proves that group A Group B and Group B are all fault-free electromagnetic voltage transformers; connect the AC ammeter in parallel between the high-voltage windings of Group B and Group C, and slowly pressurize the parallel terminals of the secondary side of Group B and Group C through the AC voltage regulator , observe the voltage value of the AC ammeter; when the indicated value of the AC ammeter does not increase significantly with the slow pressurization of the AC voltage regulator, and keeps the indicated value small, it proves that groups A, B, Group C are all fault-free electromagnetic voltage transformers, and the inspection is over;

Judgment 2: Connect the AC ammeter in parallel between the high-voltage windings of Group A and Group B, and slowly pressurize the parallel terminals of the secondary side of Group A and Group B through the AC voltage regulator, and observe the voltage value of the AC ammeter; When the indication value increases greatly with the slow pressurization of the AC voltage regulator, and finally maintains a large indication value, it proves that there is an electromagnetic voltage transformer between groups A and B with poor inter-turn insulation. Reduce the voltage regulator to zero in time; connect the AC ammeter in parallel between the high-voltage windings of Group B and Group C, and slowly pressurize the parallel terminals of the secondary side of Group B and Group C through the AC voltage regulator, observe the AC voltage The voltage value of the ammeter; when the indicated value of the AC ammeter increases greatly with the slow pressurization of the AC voltage regulator, and finally maintains a large indicated value, it proves that the electromagnetic voltage transformer of group B has inter-turn insulation If it is not good, at this time, reduce the voltage regulator to zero in time, and the inspection is over. The simple diagram of judgment is shown in Figure 2;

Judgment 3: Connect the AC ammeter in parallel between the high-voltage windings of Group A and Group B, and slowly pressurize the parallel terminals of the secondary side of Group A and Group B through the AC voltage regulator, and observe the voltage value of the AC ammeter; When the indication value increases greatly with the slow pressurization of the AC voltage regulator, and finally maintains a large indication value, it proves that there is an electromagnetic voltage transformer between groups A and B with poor inter-turn insulation. Reduce the voltage regulator to zero in time; connect the AC ammeter in parallel between the high-voltage windings of Group B and Group C, and slowly pressurize the parallel terminals of the secondary side of Group B and Group C through the AC voltage regulator, observe the AC voltage The voltage value of the ammeter; the indication value of the AC ammeter does not increase significantly with the slow pressure of the AC voltage regulator, and when the indication value remains small, it proves that there is an inter-turn in the electromagnetic voltage transformer of group A Poor insulation, at this time, reduce the voltage regulator to zero in time, and the inspection is over;

Judgment 4: Connect the corresponding windings of the secondary sides of groups A and B in parallel, connect the AC ammeter in parallel between the high-voltage windings of groups A and B, and connect the secondary sides of groups A and B in parallel through the AC voltage regulator. Slowly pressurize the terminal and observe the voltage value of the AC ammeter; when the indicated value of the AC ammeter does not increase significantly with the slow pressurization of the AC voltage regulator, and keeps the indicated value small, it proves that group A , Group B are all fault-free electromagnetic voltage transformers, and Group C is faulty; at this time, in order to verify this judgment, an AC ammeter can be connected in parallel between the high-voltage windings of Group B and Group C, and the AC voltage regulator can be used to control group B. , Slowly pressurize the parallel terminal of the secondary side of group C, observe the voltage value of the AC ammeter, the indication value of the AC ammeter increases greatly with the slow pressurization of the AC voltage regulator, and finally maintains a large indication value When it proves that the electromagnetic voltage transformer of group C has poor inter-turn insulation, at this time, reduce the voltage regulator to zero in time, and the inspection is over;

After all judgments are completed, if judgment 1 occurs, the next group of three adjacent electromagnetic voltage transformers can be coded and checked according to the methods from step 2) to step 10) in the manual until a fault is detected. electromagnetic voltage transformer.

Embodiment 2

Judging by the common sense of the actual working conditions, taking the three adjacent electromagnetic voltage transformers to be inspected as an example, there is no fault or there is only one fault, and the three voltage transformers are defined as group A and group B respectively. , Group C, select a 220V AC voltage regulator and a 750V AC voltmeter, and the difference from the first embodiment is that in the wiring detection method of the first embodiment, the conditions of judging 2, 3, and 4 are as follows:

Judgment 2: Connect the AC ammeter in parallel between the high-voltage windings of Group A and Group B, and slowly pressurize the parallel terminals of the secondary side of Group A and Group B through the AC voltage regulator, and observe the voltage value of the AC ammeter; When the indication value increases greatly with the slow pressurization of the AC voltage regulator, and finally maintains a large indication value, it proves that there is an electromagnetic voltage transformer between groups A and B with poor inter-turn insulation. Reduce the voltage regulator to zero in time; connect the AC ammeter in parallel between the high-voltage windings of Group A and Group C, and slowly pressurize the parallel terminals of the secondary side of Group A and Group C through the AC voltage regulator, observe the AC voltage The voltage value of the ammeter; when the indicated value of the AC ammeter increases greatly with the slow pressurization of the AC voltage regulator, and finally maintains a large indicated value, it proves that the electromagnetic voltage transformer of group A has inter-turn insulation If it is not good, at this time, reduce the voltage regulator to zero in time, and the inspection is over;

Judgment 3: Connect the AC ammeter in parallel between the high-voltage windings of Group A and Group B, and slowly pressurize the parallel terminals of the secondary side of Group A and Group B through the AC voltage regulator, and observe the voltage value of the AC ammeter; When the indication value increases greatly with the slow pressurization of the AC voltage regulator, and finally maintains a large indication value, it proves that there is an electromagnetic voltage transformer between groups A and B with poor inter-turn insulation. Reduce the voltage regulator to zero in time; connect the AC ammeter in parallel between the high-voltage windings of Group A and Group C, and slowly pressurize the parallel terminals of the secondary side of Group A and Group C through the AC voltage regulator, observe the AC voltage The voltage value of the ammeter; the indication value of the AC ammeter does not increase significantly with the slow pressure of the AC voltage regulator, and when the indication value remains small, it proves that there is an inter-turn in the electromagnetic voltage transformer of group B Poor insulation, at this time, reduce the voltage regulator to zero in time, and the inspection is over;

Judgment 4: Connect the corresponding windings of the secondary sides of groups A and B in parallel, connect the AC ammeter in parallel between the high-voltage windings of groups A and B, and connect the secondary sides of groups A and B in parallel through the AC voltage regulator. Slowly pressurize the terminal and observe the voltage value of the AC ammeter; when the indicated value of the AC ammeter does not increase significantly with the slow pressurization of the AC voltage regulator, and keeps the indicated value small, it proves that group A , Group B are all fault-free electromagnetic voltage transformers, and Group C is faulty; at this time, in order to verify this judgment, an AC ammeter can be connected in parallel between the high-voltage windings of Group A and Group C, and the AC voltage regulator can be used to control group A. , Slowly pressurize the parallel terminal of the secondary side of group C, observe the voltage value of the AC ammeter, the indication value of the AC ammeter increases greatly with the slow pressurization of the AC voltage regulator, and finally maintains a large indication value At this time, it is proved that the electromagnetic voltage transformer of group C has poor inter-turn insulation. At this time, the voltage regulator is lowered to zero in time, and the inspection is over.

Embodiment 3

The above embodiment mainly considers that there are no faults or there is only one fault in the adjacent three electromagnetic voltage transformers as an example, which can meet the judgment of most fault conditions. When two or more electromagnetic voltage transformers appear When the transformer fails, it can be judged according to the following principles, that is, according to the method in the first embodiment, first pressurize and measure two adjacent electromagnetic voltage transformers, when the voltmeter indicates a larger value, it means that there is one electromagnetic voltage transformer If there is poor insulation between turns, the voltage regulator should be lowered to zero in time. Repeat the above test with another unpressurized electromagnetic voltage transformer and any electromagnetic voltage transformer with overvoltage. When the measured voltage appears two times with a larger value, it means that there is a problem with the voltage transformer that is pressurized both times. When the measured voltage is larger only once, it means that the electromagnetic voltage transformer that is pressurized twice is good, and the electromagnetic voltage transformer that is only pressurized once and the measurement voltage is large is a damaged electromagnetic voltage transformer.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Those skilled in the art will recognize that many optional embodiments can also be implemented by using the solutions of the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (3)

1. A method for judging turn-to-turn insulation short circuit of an electromagnetic voltage transformer is characterized by comprising the following steps:

1) selecting a detection device for judging turn-to-turn insulation short circuit of the electromagnetic voltage transformer, wherein the detection device comprises one alternating current voltage regulator and one alternating current voltage meter;

2) taking the example that no fault or one fault occurs in all three adjacent electromagnetic voltage transformers to be detected, defining the three voltage transformers as an A group, a B group and a C group respectively, and connecting corresponding windings of the secondary sides of the A group and the B group in parallel respectively;

3) connecting the AC ammeter in parallel between the high-voltage windings of the A group and the B group, slowly pressurizing the parallel ends of the secondary sides of the A group and the B group through the AC voltage regulator, and observing the voltage value of the AC ammeter;

4) when the indication value of the alternating current meter is not greatly increased along with the slow pressurization of the alternating current voltage regulator and is kept to be a small indication value all the time, the A group and the B group are proved to be fault-free electromagnetic voltage transformers;

5) connecting the AC ammeter in parallel between the high-voltage windings of the B group and the C group, slowly pressurizing the parallel ends of the secondary sides of the B group and the C group through the AC voltage regulator, and observing the voltage value of the AC ammeter;

6) when the indication value of the alternating current meter is not greatly increased along with the slow pressurization of the alternating current voltage regulator and is kept to be smaller, the group A, the group B and the group C are proved to be fault-free electromagnetic voltage transformers, and the inspection is finished;

7) after the step 3) is carried out, the indication value of the alternating current meter is greatly increased along with the slow pressurization of the alternating current voltage regulator, and finally a large indication value is kept, so that the condition that one electromagnetic voltage transformer between the group A and the group B has poor turn-to-turn insulation is proved, the voltage regulator is timely reduced to zero, and the step 5) is repeated;

8) when the indication value of the alternating current meter is greatly increased along with the slow pressurization of the alternating current voltage regulator and finally keeps a large indication value, the B group of electromagnetic voltage transformers are proved to have poor turn-to-turn insulation, the voltage regulator is timely reduced to zero at the moment, and the inspection is finished;

9) after the step 7), the indication value of the alternating current meter is not increased to a large extent along with the slow pressurization of the alternating current voltage regulator, and when the indication value is kept small all the time, the group A electromagnetic voltage transformer is proved to have poor turn-to-turn insulation, the voltage regulator is timely reduced to zero, and the inspection is finished;

10) after the step 5) is carried out, the indicating value of the alternating current meter is greatly increased along with the slow pressurization of the alternating current voltage regulator, and finally the larger indicating value is kept, the C group of electromagnetic voltage transformers are proved to have poor turn-to-turn insulation, the voltage regulator is timely reduced to zero at the moment, and the inspection is finished;

11) after the step 6), performing code inspection on the next group of three adjacent electromagnetic voltage transformers according to the method from the step 2) to the step 10) until the electromagnetic voltage transformers with faults are detected;

the alternating current voltmeter is preferably a 750V alternating current voltmeter.

2. The method for determining an inter-turn insulation short circuit of an electromagnetic voltage transformer according to claim 1, wherein: the alternating current voltage regulator is preferably a 220V alternating current voltage regulator.

3. The method for determining an inter-turn insulation short circuit of an electromagnetic voltage transformer according to claim 1, wherein: the inspection voltage of the alternating current voltage regulator does not exceed 60V.

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