JP5587259B2 - Insulation diagnosis method for rotating electrical machines - Google Patents

Description

  The present invention relates to an insulation diagnosis technique for a stator coil in which a mica layer such as an induction motor or a generator is fixed with a resin.

  The mica piece used in the conventional stator coil insulation system of a rotating electrical machine is a relatively large thin plate, so the maximum partial discharge charge (with a frequency of about once per cycle of applied voltage at normal voltage) It is known to estimate the remaining insulation life by monitoring the secular change of the absolute value of the characteristic represented by the value of the partial discharge charge generated) and the dielectric loss tangent. For example, Patent Document 1 discloses a method for monitoring insulation of an electric machine in operation. By using a maximum discharge charge amount, a total charge amount, an average discharge current, and a discharge generation phase-charge amount-generation frequency characteristic as an evaluation index. It is described that abnormality in an insulator can be evaluated with high accuracy. In Non-Patent Document 1, Δ2 (difference between the dielectric tangent of 2 kV and the dielectric loss tangent of the rated voltage) is shown as one of the evaluation indexes, and is described as representing the amount of relative void discharge.

JP 2000-206213 A

IEEJ Technical Report No. 752

  In the above prior art, with the diversification of the insulation system, especially in the insulation system in which the mica layer is fixed with resin, the mica pieces are fine, so when the defect progresses, these mica pieces obstruct the direction of progress. Therefore, the progress direction does not necessarily match the electric field direction. For this reason, there is a problem that it is difficult to correlate the maximum partial discharge charge amount with the degree of defect development, and it is difficult to accurately evaluate the defect state.

  An object of the present invention is to provide an insulation diagnostic method that can accurately evaluate the degree of deterioration and remaining life of an insulation system of a stator coil in which a mica layer is fixed with a resin, focusing on a change in the amount of partial discharge charge. is there.

  In order to achieve the above object, the present invention continuously increases or decreases the voltage applied to the stator coil of the rotating electrical machine, acquires partial discharge charge amount pattern information with respect to the applied voltage, and the partial discharge charge amount rapidly increases. Alternatively, the state of insulation deterioration can be evaluated from the voltage, degree, and number of sudden decreases.

  According to the present invention, the defect type of the rotating electrical machine using the insulation system in which the mica layer is fixed with the resin by comparing the pattern of the partial discharge charge amount with the basic data measured in advance and the fingerprint method, It is possible to accurately evaluate the deterioration state of insulation and the remaining life of insulation.

Explanatory drawing which shows a measurement result. The thermal deterioration characteristic figure of the partial discharge charge amount pattern with respect to the applied voltage used for a diagnosis. The mechanical deterioration characteristic figure of the partial discharge charge amount pattern with respect to the applied voltage used for a diagnosis. FIG. The slot sectional view of a rotation electrical machinery. Measurement flow diagram. The schematic block diagram of a measurement system. The figure which shows the specific structure of a measurement system. Explanatory drawing of a measurement flow. FIG. 2 is a diagnosis flowchart of the first embodiment. The characteristic figure of heat deterioration measurement data. The characteristic figure of mechanical deterioration measurement data. The schematic diagram of the insulating layer after heat deterioration. The schematic diagram of the insulating layer after mechanical deterioration. FIG. 9 is a diagnosis flow diagram of the second embodiment. FIG. 6 is a diagnosis flowchart of Example 4; Explanatory drawing of remaining life estimation. Explanatory drawing of the remaining life estimation by Example 3. FIG.

  Embodiments of the present invention will be described below with reference to the drawings. First, the structure of the rotating electrical machine will be briefly described before describing the embodiments.

  FIG. 3 shows an example of the rotating electrical machine 1. The rotating electrical machine 1 is generally composed of a rotor 2 and a stator 3. As shown in FIG. 4, the stator 3 includes a stator core 4, an iron core slot 5, and a stator coil 6. The stator coil 6 includes an upper coil 6a and a bottom coil 6b. In order to secure a space between the wedge 7 and the upper bottom coil for fixing 6 to the iron core slot 5, an insulating member spacer 8 is arranged. The stator coil 6 is electrically connected outside the stator core 4.

  The stator coil 6 is composed of a wire fixing coil 9 in which several strands 9a subjected to strand insulation 10 are aligned, the strands 9a are bundled, and an insulation stuffing 11 is applied and integrated. A main insulating layer 12 is formed by winding mica tape with a glass cloth or the like as a backing material around the wire-tightening coil 9 a predetermined number of times. The stator coil 6 is formed by, for example, impregnating the main insulating layer 12 with a thermosetting resin such as an epoxy resin in an impregnation tank, and then heat-curing the thermosetting resin, or an epoxy resin or the like in advance. Some of them are formed by hot pressing a semi-cured prepreg mica tape containing a thermosetting resin. By the processing steps represented by the above, the stator coil 6 including the main insulating layer 12 having a good insulation characteristic with few defects represented by voids can be obtained.

  The main insulating layer 12 is desired to be completely filled with the mica tape layer and the thermosetting resin, but the generator coil has some defects such as voids and peeling. When a voltage equal to or higher than the partial discharge start voltage is applied to an insulating layer having voids or peeling inside, partial discharge occurs at a minute defect such as a void or peeling.

  In addition to the micro defects existing from the beginning in the insulating layer, micro defects are newly formed mainly by thermal and mechanical stress. It is known that when a thermal / mechanical / electrical / other stress is applied due to a long-term operation, the stress develops and the breakdown voltage and mechanical strength decrease.

  FIG. 5 shows a measurement flow of the partial discharge charge amount pattern with respect to the applied voltage, and FIG. 6 shows a block diagram of the measurement system.

  An AC voltage is applied to the stator coil 6 of the rotating electrical machine 1 to be measured from the high voltage power source 21 via the connection terminal 32 to boost the voltage. Note that the measurement object can be in the state of one stator coil 6 extracted from the rotating electrical machine 1. At that time, the voltage applied to the stator coil 6 and the partial discharge charge amount are measured by the diagnostic system 26. Thereafter, the voltage is boosted, and the partial discharge charge amount at that time is measured. This is repeated to obtain a partial discharge charge amount pattern with respect to the applied voltage up to a predetermined voltage. For example, a partial discharge charge amount using detection of current or electromagnetic waves is known. As an example, there is a configuration described in FIG. 4 of Japanese Patent Laid-Open No. 3-99286.

  FIG. 1 shows a result example of the partial discharge charge amount pattern with respect to the applied voltage obtained by the above method. In this embodiment, the description is based on the data at the time of step-up, but it may be based on the data at the time of step-down as shown in FIG.

  In the warning level pattern 27 in FIG. 1, when the applied voltage is increased from 0 V to a predetermined voltage, for example, about twice the operating voltage, the partial discharge charge amount has a significant difference from the background level. It consists of a voltage region in which the amount of discharge charge increases rapidly (hereinafter referred to as the first stage rising 28) and a voltage region in which the partial discharge charge amount is substantially constant thereafter. The first rise 28 of the warning level pattern 27 is a phenomenon that cannot be detected by continuous monitoring at the operating voltage. The alert level pattern 27 measured by the measurement method is a pattern at the time of thermal degradation as shown in FIG. 10A, and this is a pattern in the creeping direction as shown in the schematic diagram of FIG. This is because peeling and voids are generated and progressing, and the degree of the generation and progress tends to increase as the thermal deterioration progresses. For this reason, the mechanical strength decreases due to thermal deterioration, and the insulating layer is easily cracked by vibration, electromagnetic force, centrifugal force, or the like. In the example of FIG. 10A, this means that a defect such as a crack is easily formed in the penetration direction of the insulating layer, and it is considered necessary to take measures such as shortening the diagnosis period. Therefore, for example, it can be evaluated as a warning level.

  In the danger level pattern 29 in FIG. 1, the absolute value of the characteristic represented by the maximum partial discharge charge amount is the lowest level, but the applied voltage is increased from 0 V to a predetermined voltage, for example, about twice the operating voltage. When the first stage rises, the second stage rise 30 appears after the first stage rise 28. Similarly to the first stage rise 28 of the warning level pattern 27, the second stage rise 30 of the danger level pattern 29 is a sudden increase in the partial discharge charge amount caused by a slight voltage change. In the present invention, the applied voltage and the partial discharge charge amount can be grasped as a characteristic pattern by the pattern information of the partial discharge charge amount with respect to the applied voltage obtained continuously. The pattern 29 of the dangerous level measured by the measurement method is a pattern of mechanical deterioration as shown in FIG. 10B, which is the penetration of the insulating layer as shown in the schematic diagram of FIG. This is due to the formation and progress of microscopic cracks that progress in the layer direction, and defect bonds such as voids and delamination via cracks. For this reason, defects that progress in the penetration direction of the insulating layer are fatal defects for the insulating layer, and are likely to cause a significant decrease in insulation performance represented by dielectric breakdown voltage, such as coil sampling inspection. Since it is considered necessary to make a detailed diagnosis, for example, it can be evaluated as a danger level. However, since there is a degree of defect formation / development within the risk level, a detailed evaluation is performed based on the evaluation index described in Example 2, and a more accurate diagnosis can be made by grasping the degree of formation / development. Can be provided.

  In the monitoring level pattern 31 in FIG. 1, the maximum partial discharge charge amount is larger than the warning level pattern 27 and the dangerous level pattern 29. However, since neither of the above features is present, the heat applied to the insulating layer is large. It shows that there is no problem at the present time due to the small deterioration caused by mechanical force. For this reason, since it is thought that periodic diagnosis should be continued, it can be evaluated as a monitoring level, for example.

  FIG. 9 shows a diagnosis flow summarizing these.

  As described above, according to the present embodiment, the deterioration phenomenon due to the formation and progress of minute defects, which is difficult to appear in the absolute value of the characteristic represented by the conventional maximum partial discharge charge, is applied according to the present embodiment. Since it is possible to capture the characteristics based on the pattern of characteristics, it is possible to capture the deterioration phenomenon, which is caused by the rapid breakdown of the insulation performance represented by the breakdown voltage, which occurs with the connection of minute defects. Diagnosis of insulation diagnostic technology can be provided.

  FIG. 7 shows an example of the configuration of the diagnostic system, and FIG. 8 shows an example of the measurement flow in the configuration of FIG.

  The diagnosis system 26 includes a partial discharge measurement system 23, a voltage measurement system 22, a computer 24, and a display device 25. The computer 24 associates the applied voltage with the partial discharge charge amount and outputs it to the display device 25. At that time, if the basic data of the partial discharge charge amount pattern stored in the computer 24 is compared with the fingerprint method, the defect type and the progress of the defect can be quantified.

  An example of the measurement flow shown in FIG. 8 is shown. By setting the measurement end voltage V, the step-up or step-down speed v per second, the voltage and the time interval Δt for measuring the partial discharge charge amount, as shown in FIG. By issuing a command in synchronization with the measurement system 23, the pattern of the partial discharge charge amount with respect to the applied voltage can be automatically recorded. If such a system is constructed, more stable data collection is possible. The occurrence frequency of the partial discharge charge amount may be arbitrarily set. As an example, when the commercial frequency is 50 Hz, the generation frequency level is 50 pulses / second, and when the commercial frequency is 60 Hz, 60 pulses / second, that is, a signal having a frequency of occurrence of one or more per applied voltage cycle. Is acquired as the partial discharge charge amount, noise can be effectively removed. In addition, when Δt is about 0.5 seconds and v is about 0.1 kV / second, it has been confirmed that the balance between the number of data and the evaluation accuracy can be appropriately maintained.

  After the above setting, voltage is applied and measurement is started.

  At this time, the information on the applied voltage and the partial discharge charge amount is synchronized among the three devices by GPIB (General Purpose Interface Bus) or the like, and the computer 24, the voltage measurement system 22 and the partial discharge measurement system 23 are synchronized. Using this, a command is issued from the computer 24 to the voltage measurement system 22 and the partial discharge measurement system 23, and the respective information is recorded at the set measurement intervals and sequentially stored in the computer 24.

  When the measurement is completed, the result of the partial discharge charge amount pattern with respect to the applied voltage is displayed on the display device 25 based on the information on the applied voltage and the partial discharge charge amount stored in the computer 24. The result may be displayed at any time simultaneously with the measurement.

  Diagnosis is performed based on the result obtained by the display device 25. The functions of the computer 24 and the display device 25 may be integrated.

  In the present embodiment, the first stage rise 28 of the warning level pattern 27 in FIG. 1 in the first embodiment is evaluated using V1 and Q1 in FIG. This is an insulation diagnostic method for evaluating the mechanical deterioration level of the rising edge 28 of the first stage and the rising edge 30 of the second stage of the pattern 29 using V1, V2, and Q2 of FIG. A diagnosis flow using this embodiment is shown in FIG. In the present embodiment, the description is based on the data at the time of step-up, but it may be based on the data at the time of step-down, that is, V1 ′, Q1 ′ in FIG.

  In the thermal deterioration, as shown in FIG. 10A, the start voltage V1 of the first-stage rising 28 is reduced to V1d compared to the initial value V1s, and the partial discharge charge amount Q1 at which the increase rate of the partial discharge charge amount is decreased. It will be confirmed. FIG. 12 shows a diagnosis flow when Q1 ≧ 5000 pC is set as an example.

  In the mechanical degradation, as shown in FIG. 10B, it is confirmed that the start voltage V1 at the first stage rises to V1d as compared with the initial value V1s as the mechanical force increases. In addition, it has been confirmed that the applied voltage at the start point of the second stage rise is V2, and the partial discharge charge amount at the start point is Q2, both of which tend to decrease as the mechanical force increases. The decrease in V1 represents the formation / progress of defect bonds such as voids and delamination via cracks, and the decrease in V2 and Q2 represents the formation / progress of minute cracks. By using these indices, it is possible to evaluate the formation / progress of cracks that propagate in the penetration direction of the insulating layer due to mechanical force, and to estimate the remaining life as shown in FIG.

  According to the present embodiment, it is possible to evaluate the thermal deterioration level and the mechanical deterioration level, and therefore, it is possible to provide a remaining insulation life diagnosis technology that further subdivides the warning level and the danger level in consideration of both. it can.

  The present embodiment is an insulation diagnosis method capable of grasping formation and progress of defects over time by combining measurement results by combining initial values and values at the time of periodic inspection.

  V1, V2, and Q2 tend to decrease as defects are formed and progress. By plotting the initial value and the value at the periodical inspection on the master curve for the life of each value as shown in Fig. 15, and evaluating the change of each value, grasp the formation and progress of defects over time. It is possible to estimate the life limit period. In addition, it is possible to perform a remaining life diagnosis according to each device having a different deterioration rate due to an operation state or the like.

  According to the present embodiment, the accuracy of evaluation of deterioration over time can be improved, and the remaining insulation life can be diagnosed more accurately.

  In this embodiment, in addition to the methods of Embodiments 1, 2, and 3, the difference between the dielectric tangent of 2 kV and the dielectric loss tangent of the rated voltage (hereinafter referred to as Δ2) among the dielectric characteristics for evaluating the insulating layer. It is an insulation diagnosis method that can evaluate deterioration of an insulating layer from a viewpoint different from the partial discharge characteristics. FIG. 13 shows a diagnosis flow in which Δ2 is added.

  Among the dielectric characteristics, Δ2 is widely known as an index for evaluating the amount of relative void discharge in the insulating layer, as described in IEEJ Technical Report No. 752. On the other hand, as with the maximum partial discharge charge amount, it has been confirmed that it is difficult to capture the formation and progress of minute defects. In addition, Δ2 may vary depending on factors such as the measurement environment (in the field or test site) and the shape of the measurement target (actual machine structure or sampling coil), so the judgment value can be changed according to each measurement condition. Also good. Here, as an example, a diagnosis flow when Δ2 ≧ 2% and the level requiring attention is set is shown. When heat deterioration and mechanical deterioration are combined, Q1 which is one of the characteristic amounts of heat deterioration may be smaller than 5000 pC set as an example in the second embodiment. On the other hand, Δ2 can accurately diagnose thermal degradation even when complex degradation is applied. Therefore, when thermal degradation and mechanical degradation are combined, it is possible to diagnose thermal degradation with Δ2 and mechanical degradation with the risk level pattern 29 in FIG. Even in the case of deterioration, accurate insulation diagnosis is possible by isolating the deterioration.

DESCRIPTION OF SYMBOLS 1 Rotating electrical machine 2 Rotor 3 Stator 4 Stator core 5 Iron core slot 6 Stator coil 6a Top coil 6b Bottom coil 7 Wedge 8 Insulation member spacer 9 Stranding coil 9a Strand 10 Strand insulation 11 Insulation padding 12 Main insulation Layer 21 High voltage power supply 22 Voltage measurement system 23 Partial discharge measurement system 24 Computer 25 Display device 26 Diagnostic system 27 Warning level pattern 28 First stage rise 29 Danger level pattern 30 Second stage rise 31 Monitoring level Pattern 32 connection terminal

Claims (5)

  The partial discharge charge amount increases with a significant difference from the background level in the pattern information of the partial discharge charge amount with respect to the applied voltage obtained by continuously boosting or lowering the voltage applied to the stator coil of the rotating electrical machine. A case in which the rate of increase of the partial discharge charge increases again at the applied voltage higher than the voltage region (rising of the first stage) (rising of the second stage) is a mechanical deterioration pattern, Insulation diagnostic method characterized by diagnosis. Of pattern information of the partial discharge charge amount for the obtained applied voltage The method of claim 1, applied voltage that partial discharge charge quantity of rising electricity pressure region of the first stage begins to increase, or, , insulation diagnostic method of claim 1 wherein characterized in that to evaluate the degree of the risk level based on the voltage applied that partial discharge charge quantity of rising realm of the second stage starts to increase. Of pattern information of the partial discharge charge amount for the obtained applied voltage The method of claim 1, the partial discharge charge quantity of points partial discharge charge quantity of rising electricity pressure region of the first stage begins to increase or, according to claim 1 wherein characterized in that to evaluate the degree of the risk level based on the partial discharge electric load volume of that partial discharge charge quantity of rising realm of the second stage starts to increase of insulation diagnosis method.   The partial discharge charge amount increases with a significant difference from the background level in the pattern information of the partial discharge charge amount with respect to the applied voltage obtained by continuously boosting or lowering the voltage applied to the stator coil of the rotating electrical machine. An insulation diagnosis method characterized by diagnosing a warning level by using a voltage region in which a voltage region and a voltage region in which a partial discharge charge amount is substantially constant as a thermal deterioration pattern. The insulation diagnosis according to any one of claims 1 to 4, wherein the dielectric diagnosis of the insulating layer is evaluated using the difference between the dielectric loss tangent of 2 kV and the dielectric loss tangent of the rated voltage. 5. The insulation diagnostic method according to any one of items 1 to 4.