JP2016212122A - Partial discharge measuring system using repeated impulse voltages and partial discharge measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a partial discharge measuring system using repeated impulse voltages in which work by a user can be reduced as much as possible.SOLUTION: A partial discharge measuring system using repeated impulse voltages comprises impulse voltage application means, impulse voltage control means, and partial discharge count means. The impulse voltage application means generates a plurality of impulse voltages and applies them to a measuring target. The partial discharge count means counts how many times partial discharge occurs on the basis of a detection signal outputted from partial discharge detection means which detects the partial discharge in the measuring target. The impulse voltage control means controls the impulse voltage application means to apply a specific number of impulse voltages having the same peak value to the measuring target. The partial discharge count means counts how many times the partial discharge occurs each time the specified number of impulse voltages are applied to the measuring target.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a partial discharge measurement system and a partial discharge measurement method using a repetitive impulse voltage.

  It is well known that when an electric motor is driven by an inverter, a surge voltage is generated due to high-speed switching in the inverter, and the insulation of the electric motor winding is affected. Such a surge voltage is called an inverter surge and may reach twice or more the rated voltage of the electric motor. When the inverter surge is applied to the motor winding, there is a concern that partial discharge occurs inside or outside the winding. Such partial discharge becomes a cause of deteriorating the coating of the enamel wire constituting the winding. When the coating deteriorates, dielectric breakdown will eventually occur. Therefore, it is desirable for an electric motor to have an insulation design so that partial discharge does not occur even if an inverter surge is applied to the winding.

  Conventionally, the insulation performance of an electric motor winding has been evaluated based on partial discharge characteristics by application of an alternating voltage, in particular, partial discharge start voltage. However, the potential distribution in the winding differs between when the AC voltage is applied and when the surge voltage is applied. Therefore, it is desirable that the insulation performance of the inverter-driven electric motor is evaluated by applying an impulse voltage that simulates a surge voltage. Further, in the case of partial discharge measurement by applying an impulse voltage, the voltage changes sharply at the rise of the impulse voltage (at the start of application), and thus a method different from the partial discharge measurement by applying an AC voltage is required.

  For this reason, various investigations have been made on partial discharge measurement methods in the case where a repetitive impulse voltage is applied (see, for example, Non-Patent Documents 1 to 3). In those examinations, the partial discharge start voltage is set only when the number of impulses in which partial discharge has occurred exceeds the specified number of all applied impulse voltages (hereinafter referred to as the number of impulses). This is defined as the partial discharge start voltage in the repetitive impulse voltage.

  Further, the partial discharge start voltage at the repetitive impulse voltage is measured as follows. FIG. 11 shows a repetitive impulse voltage (applied voltage waveform) and a sensor output signal (partial discharge signal) output from the partial discharge sensor. As shown in FIG. 11, in the measurement, 10 impulses are applied at a first time (for example, 20 ms) interval, and 10 impulses boosted by 10 V after the second time (for example, 100 ms) are further applied. The operation is repeatedly executed. Such an operation is repeated until the impulse voltage reaches a stop value (for example, 2 kV) from a start value (for example, 1 kV). The voltage values referred to here are all impulse peak values.

  In such measurement, all data of the applied voltage waveform and the sensor output signal are stored from the start to the end of the application of the impulse voltage. Then, after the application of the impulse voltage is stopped, the partial discharge start voltage is calculated by performing the following processing on each data by the measurer. That is, each stored data is divided for each period in which ten impulse voltages having the same peak value are applied. Then, for each of the divided periods, the number of occurrences of partial discharge is counted based on the sensor output signal. As a result, the partial discharge start voltage at the impulse voltage is calculated repeatedly from the applied voltage waveform during the period when the number of occurrences of partial discharge is 5 or more. In short, in the above method, each data is continuously measured from the start to the end of application of the impulse voltage, and the partial discharge start voltage is derived from the data processing after the end of the measurement.

IEC 61934TS 40th Symposium on Electrical and Electronic Insulation Materials System D-1 The 40th Symposium on Electrical and Electronic Insulation Materials System P-7

  Therefore, a partial discharge measurement system and a partial discharge measurement method using a repetitive impulse voltage that can reduce the work by the user as much as possible are provided.

  The partial discharge measurement system using a repetitive impulse voltage according to the present embodiment includes an impulse voltage application unit that generates a plurality of impulse voltages and applies the impulse voltage to an object to be measured, an impulse voltage control unit that controls the impulse voltage application unit, A partial discharge number counting means for counting the number of occurrences of the partial discharge based on a detection signal output from a partial discharge detection means for detecting a partial discharge in the measurement object, and a voltage value applied to the measurement object is calculated. Voltage value calculation means for controlling the impulse voltage application means so that a prescribed number of impulse voltages having the same peak value are applied to the measurement object, The partial discharge number counting means is configured so that each time a specified number of impulse voltages are applied to the measurement target, The impulse voltage control means counts the number of occurrences of discharge, and the impulse voltage according to a repetitive pattern in which the peak value of the impulse voltage is increased stepwise each time the specified number of impulse voltages are applied is the measurement object. The impulse voltage application means is controlled so that the voltage value is calculated by the voltage value calculation means when the partial discharge count is first counted more than a specified number by the partial discharge number counting means. The partial discharge start voltage is determined, the impulse voltage application unit is controlled to stop the application of the impulse voltage, and the impulse voltage control unit further counts the number of partial discharges after the application of the impulse voltage is stopped. From the state where the partial discharge more than the specified number of times is counted by the means, the specified number of impulsions Controlling the impulse voltage application means so that an impulse voltage according to a repetitive pattern in which a peak value of the impulse voltage is lowered step by step each time a voltage is applied is applied to the measurement object, and the partial discharge number counting means Thus, when the partial discharge less than the prescribed number of times is first counted, the voltage value calculated by the voltage value calculation means is determined as a partial discharge extinction voltage.

  Further, in the partial discharge measurement method using the repetitive impulse voltage of the present embodiment, a prescribed number of impulse voltages having the same peak value are applied to the measurement object, and each time the prescribed number of impulse voltages are applied, The number of occurrences of the partial discharge is counted based on a detection signal output from a partial discharge detection means for detecting a partial discharge in the measurement object, and the peak of the impulse voltage is applied each time the specified number of impulse voltages are applied. Impulse voltage according to a repetitive pattern in which the value is increased stepwise is applied to the measurement object, and when the partial discharge is counted more than the specified number of times for the first time, partial discharge is started for the voltage value applied to the measurement object. It is determined as a voltage, the application of the impulse voltage is stopped, and after the application of the impulse voltage is stopped, a predetermined number of times or more From the state where the partial discharge is counted, an impulse voltage is applied to the measurement object according to a repetitive pattern in which the peak value of the impulse voltage is decreased stepwise each time the specified number of impulse voltages are applied. When a partial discharge less than the number of times is counted, a voltage value applied to the measurement object is determined as a partial discharge extinction voltage.

The block diagram of a partial discharge measuring system showing the first embodiment Flow chart showing measurement procedure of partial discharge start voltage Diagram showing typical applied voltage waveform and partial discharge signal Diagram showing an example of impulse voltage waveform The figure which shows the partial discharge signal before and after an absolute value process is performed The figure which shows the applied voltage waveform and partial discharge signal in partial discharge start voltage measurement Flow chart showing measurement procedure of partial discharge start voltage and partial discharge extinction voltage FIG. 1 equivalent diagram showing the second embodiment 2 equivalent diagram 7 equivalent diagram FIG. 6 equivalent diagram showing the prior art

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram showing a schematic configuration of a partial discharge measurement system. A partial discharge measurement system 1 shown in FIG. 1 measures partial discharge by repeatedly applying an impulse voltage to an electric motor 2 that is a measurement object. The partial discharge measurement system 1 includes an impulse power supply 3, a partial discharge detection device 4, a measurement control device 5, and the like.

  The impulse power supply 3 (corresponding to an impulse voltage application unit) generates a plurality of impulse voltages having peak values according to a command given from the measurement control device 5. Other characteristics such as the rise time and fall time of the impulse voltage to be generated are predetermined specifications. In addition, about the other characteristic, the structure which enables the change by a user may be sufficient. An impulse voltage generated by the impulse power supply 3 is applied to the electric motor 2. In the present embodiment, the impulse voltage is applied between the phases of the winding of the electric motor 2 that is an example of the application location (for example, between the U phase and the V phase). The impulse voltage is not limited to the voltage applied to the illustrated location, and may be applied between other phases of the winding of the motor 2 or between the winding of the motor 2 and the iron core, for example.

  The partial discharge detection device 4 (corresponding to partial discharge detection means) detects partial discharge generated in the electric motor 2 and outputs a partial discharge signal that is a detection signal based on (occurrence degree of) partial discharge. As the partial discharge detection device 4, for example, a partial discharge such as a configuration in which a current flowing in the winding of the motor 2 is detected by CT (Current Transformer) or an electromagnetic wave around the winding of the motor 2 is detected by an antenna or a probe. In general, it is possible to adopt a configuration that detects (changes in) a physical quantity that accompanies this.

  The measurement control device 5 is configured based on, for example, a personal computer on which Windows (registered trademark) is mounted as an OS (Operating System). The measurement control apparatus 5 includes an interface for operating various application programs to be described later and inputting / outputting signals to / from the outside. Thereby, the measurement control apparatus 5 implement | achieves the function as a digital oscilloscope which displays the input signal waveform on a screen, and the function which controls the measurement of partial discharge.

  The measurement control device 5 includes a voltage control program 6, an initial voltage acquisition program 7, an applied voltage waveform observation circuit 8, a discharge frequency calculation program 9, a voltage value calculation program 10, a partial discharge signal observation circuit 11, and a threshold setting program 12. I have. The voltage control program 6 (corresponding to the impulse voltage control means) controls the operation of the impulse power supply 3 so that a specified number (for example, 10) of impulse voltages having the same peak value is applied to the electric motor 2. Accordingly, the peak value of the impulse voltage generated by the impulse power supply 3 is determined by the voltage control program 6.

  The initial voltage acquisition program 7 (corresponding to the approximate voltage value input means) displays an input field for setting the initial voltage V0 on the display panel (display) of the measurement control device 5. Then, the initial voltage acquisition program 7 acquires the value of the initial voltage V0 input by the user using a keyboard or the like, and transfers the acquired value to the voltage control program 6. The voltage control program 6 sets the peak value of the impulse voltage based on the acquired value of the initial voltage V0. The voltage control program 6 controls the impulse power supply 3 via a communication interface for performing communication such as RS232C, for example.

  An applied voltage waveform observation circuit 8 (corresponding to applied voltage waveform observation means) observes the waveform of the voltage output from the external voltage detector 13. The voltage detector 13 is a voltage divider, for example, and divides and outputs the voltage between the U phase and the V phase of the electric motor 2. With such a configuration, the applied voltage waveform observation circuit 8 indirectly observes the waveform of the voltage applied to the electric motor 2. The voltage waveform (data representing) observed by the applied voltage waveform observation circuit 8 is transferred to the discharge frequency calculation program 9 and the voltage value calculation program 10.

  The voltage value calculation program 10 (corresponding to a voltage value calculation means) calculates a voltage value (voltage peak value) applied to the electric motor 2 based on the transferred voltage waveform. The voltage value calculated by the voltage value calculation program 10 is transferred to the discharge frequency calculation program 9. The partial discharge signal observation circuit 11 observes the waveform of the partial discharge signal output from the partial discharge detection device 4. The waveform of the partial discharge signal observed by the partial discharge signal observation circuit 11 is transferred to the discharge count calculation program 9.

The threshold value setting program 12 (corresponding to threshold value setting means) displays an input field for setting the discharge determination threshold value S _th on the display panel (display) of the measurement control device 5. Then, the threshold value setting program 12 acquires the discharge determination threshold value S _th input by the user using a keyboard or the like. The discharge determination threshold value S _th acquired by the threshold value setting program 12 is transferred to the discharge frequency calculation program 9.

The discharge number calculation program 9 (corresponding to the partial discharge number counting means) is an application voltage waveform observed by the application voltage waveform observation circuit 8, a partial discharge signal waveform observed by the partial discharge signal observation circuit 11, and a threshold setting program. The number of occurrences of partial discharge is counted by performing an evaluation (details will be described later) using the discharge determination threshold value S _th acquired in _Step 12.

  As described above, according to the partial discharge measurement system 1, a specified number of impulse voltages having the same peak value are applied to the electric motor 2, and the number of occurrences of partial discharge is counted each time. The user can measure the partial discharge using the number of occurrences of partial discharge (data representing) obtained every time the prescribed number of impulse voltages are applied. For example, it is possible to perform measurement such as determining that a partial discharge is not generated more than a predetermined number of times when a test impulse voltage having a predetermined peak value is applied to the electric motor 2.

  In addition, the partial discharge start voltage can be measured. In this case, the voltage control program 6 applies an impulse voltage to the motor 2 in accordance with a repetitive pattern in which the peak value of the impulse voltage is increased stepwise every time a specified number of impulse voltages having the same peak value are applied. Thus, the impulse power supply 3 is controlled. FIG. 2 is a flowchart showing a procedure for measuring the partial discharge start voltage.

In step S1, the threshold value setting program 12 reads the discharge determination threshold value _Sth set in the input field of the display panel of the measurement control device 5. In step S2, the initial voltage acquisition program 7 reads the initial voltage V0 (for example, 1 kV) set in the input field of the display panel of the measurement control device 5. In step S3, the voltage control program 6 initializes an instruction voltage Va for instructing an output voltage (peak value) of the impulse power supply 3 (instruction voltage Va = initial voltage V0).

  In step S4, the voltage control program 6 instructs the impulse power supply 3 to generate an impulse voltage. Thereby, a specified number (for example, 10) of impulse voltages having a peak value of the command voltage Va is applied to the electric motor 2 (step S5). The impulse power supply 3 is set in advance so as to apply the specified number of impulse voltages. In step S <b> 6, a voltage waveform (applied voltage waveform) applied to the electric motor 2 is observed by the applied voltage waveform observation circuit 8. In step S7, the partial discharge signal observation circuit 11 observes the waveform (partial discharge signal waveform) of the partial discharge signal output from the partial discharge detection device 4.

  FIG. 3 is a waveform diagram showing an applied voltage and a partial discharge signal. FIG. 3A shows a typical applied voltage waveform observed when an impulse voltage is applied to the motor. FIG. 3B shows the waveform of the partial discharge signal observed by the partial discharge signal observation circuit 11. In the present embodiment, the impulse voltage applied to the electric motor 2 is a negative impulse voltage as shown in FIG. 4, for example.

  Since the partial discharge is generated when a high voltage is applied to a location where the enamel wire constituting the winding of the electric motor 2 is in contact, it is near the peak of the impulse voltage (applied voltage waveform) (period near time t2 in FIG. 3). Often occurs. On the other hand, in the time zone when the impulse voltage rises (period from time t0 to t1 in FIG. 3), noise accompanying voltage generation by the impulse power supply 3 may occur, and the noise may be superimposed on the partial discharge signal. In addition, noise also occurs during a time period in which the impulse voltage falls (period after time t2 in FIG. 3), and the noise may be superimposed on the partial discharge signal.

  If noise is superimposed on the partial discharge signal, the partial discharge cannot be accurately measured. Therefore, in step S8, the following mask processing is performed on the partial discharge signal waveform transferred from the partial discharge signal observation circuit 11 by the discharge number calculation program 9. That is, a period from a time point after the elapse of a predetermined time from the start of rising of the impulse voltage (time t1 in FIG. 3) to a time point at which the applied voltage waveform zero-crosses (time t3 in FIG. 3) corresponds to a specified time period (count valid period). ). Note that the time point after the elapse of the predetermined time can be appropriately changed as long as it is a time point before the vicinity of the peak of the impulse voltage (applied voltage waveform).

  Then, signal processing is performed on the partial discharge signal waveform so that the specified time period is valid. FIG. 3C shows the waveform of the partial discharge signal after such mask processing. As shown in FIG. 3C, the partial discharge signal waveform after the mask process is such that the superimposed noise component is removed and only the signal component corresponding to the occurrence of the partial discharge appears.

FIG. 5A shows a partial discharge signal before the absolute value processing described later is performed. FIG. 5B shows a partial discharge signal after the absolute value processing is performed. The partial discharge signal output from the partial discharge signal observation circuit 11 often has a high-frequency damped oscillation waveform. Therefore, in the partial discharge signal, it is not determined which of the positive peak and the negative peak is larger. Therefore, even if such a partial discharge signal is compared with a discharge determination threshold value S _th that is a constant value, it is difficult to accurately determine the partial discharge. Therefore, in step S9, the discharge number calculation program 9 performs absolute value processing on the partial discharge signal (partial discharge signal after masking) output from the partial discharge signal observation circuit 11.

The number-of-discharges calculation program 9 counts the number of occurrences of partial discharge based on the partial discharge signal after the mask process and the absolute value process are performed as follows. That is, in step S10, the partial discharge signal after each process is compared with the discharge determination threshold value _Sth by the discharge frequency calculation program 9. As a result of the comparison, if the partial discharge signal exceeds the discharge determination threshold _Sth , it is determined that partial discharge has occurred. In this way, the discharge number calculation program 9 counts (calculates) the partial discharge number C _pd which is the number of occurrences of partial discharge.

In step S11, a predetermined number of times _{C th} and the partial discharge frequency _{C pd} are compared. When the number of partial discharges C _pd is less than the specified number of times C _th (“NO” in step S11), the process proceeds to step S12. In the present embodiment, the specified number of times C _th is, for example, “5” that is ½ of the specified number “10” described above. In step S12, the instruction voltage Va is updated by the voltage control program 6. Specifically, the instruction voltage Va is set to a voltage that is higher than the instruction voltage Va at that time by a predetermined voltage ΔV (for example, 10 V, 100 V, etc.) (Va = Va + ΔV).

In step S13, the instruction voltage Va whether does not exceed the upper limit value _{V max} are determined. This step S13, for some reason such as failure, in a case where the instruction voltage times even partial discharge continues to raise the Va C _pd is not more than a specified number C _th, provided to prevent falling into an infinite loop Yes. Therefore, the upper limit value V _max may be set to a voltage sufficiently higher value than the partial discharge inception voltage is typically assumed. When the instruction voltage Va exceeds the upper limit value _{V max} ( "YES" in step S13), and the processing is terminated. On the other hand, when the instruction voltage Va is equal to or less than the upper limit value _{V max} ( "NO" in step S13), and returns to step S4, the processing of step S4 and subsequent steps are executed again.

On the other hand, when the number of partial discharges C _pd is equal to or greater than the specified number of times C _th (“YES” in step S11), the process proceeds to step S14. In step S14, the voltage value calculation program 10 calculates the voltage value V _pdiv applied to the motor 2 at this time, and the process ends. The voltage value V _pdiv calculated in step S14 becomes the partial discharge start voltage in the repetitive impulse.

According to the partial discharge measurement of the present embodiment based on the above process, every time ten impulse voltages are applied until the partial discharge number C _pd is equal to or greater than the predetermined number C _th (“YES” in step S11), the impulse is applied. An impulse voltage is applied to the electric motor 2 according to a repetitive pattern in which the peak value of the voltage is increased step by step by a predetermined voltage ΔV. FIG. 6 shows an applied voltage waveform and a partial discharge signal in such partial discharge measurement. In FIG. 6, the initial value of the instruction voltage Va is represented as V0 (for example, 1 kV), the predetermined voltage ΔV is represented as, for example, 100 V, and the instruction voltage Va after the nth update is represented as Vn. As shown in FIG. 6, when an instruction voltage Va is voltage V0～V5, the partial discharge frequency _{C pd} is less than the specified number of times _{C th.} Then, when the instruction voltage Va is the voltage V6, the partial discharge number C _pd becomes the specified number of times C _th or more for the first time. Therefore, in this case, it is determined that the voltage V6 (for example, 1.6 kV) is the partial discharge start voltage,
The impulse voltage is stopped.

  After obtaining the partial discharge start voltage in this way, it is also possible to measure the partial discharge extinction voltage. In this case, the voltage control program 6 applies an impulse voltage according to a repetitive pattern in which the peak value of the impulse voltage is lowered step by step to the electric motor 2 every time a specified number of impulse voltages having the same peak value are applied. Thus, the impulse power supply 3 is controlled. FIG. 7 is a flowchart showing a procedure for measuring the partial discharge start voltage and the partial discharge extinction.

In FIG. 7, steps S1 to S14 are the same as those in FIG. Then, after the voltage value calculation program 10 calculates the voltage value V _pdiv (partial discharge start voltage) in step S14, the _{process proceeds to} step T1. In step T1, the command voltage Va is updated by the voltage control program 6. Specifically, the instruction voltage Va is set to a voltage lower than the instruction voltage Va at that time by a predetermined voltage ΔV (for example, 10 V, 100 V, etc.) (Va = Va−ΔV).

In step T2, the instruction voltage Va whether not below the lower limit value V _min is determined. This step T2 is provided for the same reason as step S13 shown in FIG. For this reason, the lower limit value V _min is preferably set to a voltage value sufficiently lower than the normally assumed partial discharge extinction voltage. If the command voltage Va is below the lower limit value V _min (“YES” in step T2), the process is terminated as it is. On the other hand, when the instruction voltage Va is equal to or higher than the lower limit value _min (“NO” in step T2), the processing similar to steps S4 to S10 shown in FIG. 2 is performed, and then the process proceeds to step T3.

In step T3, a predetermined number of times _{C th} and the partial discharge frequency _{C pd} are compared. When the number of partial discharges C _pd is equal to or greater than the specified number of times C _th (“YES” in step T3), the process returns to step T1. On the other hand, when the number of partial discharges C _pd is less than the specified number of times C _th (“NO” in step T3), the process proceeds to step T4. In step T4, the voltage value calculation program 10 calculates the voltage value V _pdev applied to the motor 2 at this time, and the process ends. The voltage value V _pdev calculated in step T4 becomes the partial discharge extinction voltage in the repetitive impulse.

As described above, the partial discharge measurement system 1 of the present embodiment applies a specified number of impulse voltages to the electric motor 2 and calculates the partial discharge frequency C _pd each time. The user can perform various partial discharge measurement operations such as measurement of partial discharge start voltage and measurement of partial discharge extinction voltage by using the number of partial discharges Cpd acquired by the partial discharge measurement system 1. Become. As described above, according to the partial discharge measurement system 1 of the present embodiment, since there are fewer opportunities for the user to perform an operation that affects the measurement accuracy, such as reading a meter or a display numerical value, a highly accurate partial discharge measurement is possible. The effect that it can measure is acquired.

When the partial discharge start voltage is measured, the application of the impulse voltage is immediately stopped when the partial discharge number C _pd is determined to be equal to or greater than the specified number C _th . Further, when the partial discharge extinction voltage is measured, the application of the impulse voltage is immediately stopped when the partial discharge number C _pd is determined to be less than the specified number C _th . From such a thing, the effect that the time which a partial discharge measurement requires is shortened is acquired. Furthermore, an excessive voltage application to the winding of the electric motor 2 that is the measurement object is suppressed, and an effect that it is possible to prevent a situation in which excessive damage is given to the measurement object can be obtained.

  In addition, the measurement control device 5 observes an applied voltage waveform and a partial discharge signal each time a specified number of impulse voltages are applied. Therefore, the time for which various data (data representing the applied voltage waveform or partial discharge signal) is taken into the measurement control device 5 is limited to the application time of the impulse voltage. By limiting the data acquisition time in this way, the measurement control device 5 can be configured using a relatively inexpensive device (for example, a personal computer) that does not include a large amount of memory.

If the partial discharge extinction voltage is measured together with the partial discharge start voltage using the partial discharge measurement system 1 of the present embodiment, a margin for safety can be reliably set when setting a withstand voltage or the like for the winding of the motor 2. It becomes possible to do. Further, the margin for safety can be set more reliably by setting the breakdown voltage and the like in consideration of the partial discharge frequency C _pd corresponding to the voltage values before and after the partial discharge start voltage or partial discharge extinction voltage is calculated. It becomes possible.

The number-of-discharges calculation program 9 determines a specified time zone based on the applied voltage waveform observed by the applied voltage waveform observation circuit 8 (performs mask processing), and counts partial discharges generated in the specified time zone as a target for counting. Yes. Therefore, the effect of the noise superimposed on the partial discharge signal is eliminated as much as possible, and the effect that the measurement accuracy of the partial discharge can be improved is obtained. The discharge number calculation program 9 counts the number of occurrences of partial discharge based on the partial discharge signal after the absolute value processing is performed. Therefore, even if the partial discharge signal output from the partial discharge signal observation circuit 11 has a high-frequency damped oscillation waveform, the partial discharge is determined by comparison with the discharge determination threshold value S _th that is a constant value. The effect that it can perform correctly is acquired.

  When a low voltage value (for example, 0V) is set as the initial voltage V0, it takes a long time to boost the voltage to a voltage (for example, several kV) at which partial discharge occurs. Since the voltage at which partial discharge occurs (partial discharge start voltage, partial discharge extinction voltage) is data having large variations, it is common to average a plurality of measured values to form one data. Therefore, taking much time for one measurement leads to deterioration in test efficiency. Therefore, it is preferable to grasp the approximate value of the partial discharge start voltage by performing the following test in the preparation stage of the partial discharge measurement.

  That is, an impulse voltage (or AC voltage) having a predetermined peak value is applied to the electric motor 2 one by one, and partial discharge is detected each time. And let the peak value of the voltage when partial discharge generate | occur | produce be an approximate value of partial discharge start voltage. It is only necessary to grasp the approximate value of the partial discharge start voltage (corresponding to the partial discharge start approximate voltage value) by a simple test in such a preparation stage and set the initial voltage V0 based on the approximate value. For example, a value obtained by multiplying the approximate value by a predetermined ratio (for example, 50%) may be set as the initial voltage V0. If the initial voltage V0 is set in this way, the time to reach the voltage at which partial discharge occurs is shortened compared to the case where a low initial voltage V0 is set, and the test efficiency of partial discharge measurement is improved. can get.

(Second Embodiment)
Hereinafter, the second embodiment of the present invention will be described mainly with respect to portions different from the first embodiment with reference to FIGS. 8 to 10.
FIG. 8 is a view corresponding to FIG. 1 in the first embodiment, and is a block diagram showing a configuration of the present embodiment. The partial discharge measurement system 21 of the present embodiment is different from the partial discharge measurement system 1 of the first embodiment in that a measurement control device 22 is provided instead of the measurement control device 5. The measurement control device 22 includes a repetition count control program 23 and a data storage device 24 in addition to the configuration of the measurement control device 5.

  The repeat count control program 23 (corresponding to the repeat execution control means) repeatedly executes measurement of partial discharge (partial discharge start voltage, partial discharge extinction voltage) a set number of times. The data storage device 24 (corresponding to data recording means) includes a data storage program 25 and a magnetic storage device 26 such as a hard disk. The data storage device 24 files the partial discharge number calculated by the discharge number calculation program 9 and the voltage value calculated by the voltage value calculation program 10 by the data storage program 25 and stores them in the magnetic storage device 26.

  Next, a method of measuring the partial discharge start voltage by the partial discharge measurement system 21 having the above configuration will be described. FIG. 9 is a diagram corresponding to FIG. 2 in the first embodiment, and is a flowchart showing a procedure for measuring the partial discharge start voltage in the present embodiment. The measurement procedure of the present embodiment shown in FIG. 9 is different from the measurement procedure of the first embodiment shown in FIG. 2 in that steps U1 and U2 are added.

In step S14, after the voltage value calculation program 10 calculates the voltage value V _pdiv (corresponding to the partial discharge start voltage), the _{process proceeds to} step U1. In step U 1, the voltage value V _pdiv is _filed by the data storage program 25 and stored in the magnetic storage device 26. In the following step U2, it is determined whether or not the measurement of the partial discharge start voltage has been performed a predetermined number of times. If the measurement of the partial discharge start voltage has not been performed for the number of repetitions (“NO” in step U2), the process returns to step S3, and the measurement of the partial discharge start voltage is performed again. On the other hand, if the measurement of the partial discharge start voltage has been performed for the number of repetitions (“YES” in step U2), the process ends.

  Next, a method for measuring the partial discharge start voltage and the partial discharge extinction voltage by the partial discharge measurement system 21 having the above configuration will be described. FIG. 10 is a view corresponding to FIG. 7 in the first embodiment, and is a flowchart showing a procedure for measuring the partial discharge start voltage and the partial discharge extinction voltage in the present embodiment. The measurement procedure of this embodiment shown in FIG. 9 is different from the measurement procedure of the first embodiment shown in FIG. 7 in that steps V1 and V2 are added.

In step T4, the voltage value calculation program 10 calculates the voltage value V _pdev (corresponding to the partial discharge extinction voltage), and then the _{process proceeds to} step V1. In step V _{<b> 1} , the voltage value V _pdiv and the voltage value V _pdev are _filed by the data saving program 25 and saved in the magnetic storage device 26. In the subsequent step V2, it is determined whether or not the measurement of the partial discharge start voltage and the partial discharge extinction voltage has been performed a predetermined number of times. If each measurement has not been performed for the number of repetitions (“NO” in step V2), the process returns to step S3, and the partial discharge start voltage and the partial discharge extinction voltage are measured again. On the other hand, when each measurement has been performed for the number of repetitions (“YES” in step V2), the process ends.

  As described above, in the partial discharge measurement system 21 of the present embodiment, the calculated partial discharge start voltage is filed and stored by the application program of the measurement control device 5. In general, the partial discharge start voltage and the partial discharge extinction voltage vary greatly in measured values, and data obtained by performing a plurality of measurements under one measurement condition is often statistically processed. Therefore, according to this embodiment, it is not necessary for the user (measurer) to read the meter or the displayed numerical value every time and write the measurement results (partial discharge occurrence number, partial discharge start voltage, partial discharge extinction voltage, etc.) In addition to being able to shorten the time, there is an effect that statistical processing such as obtaining an average of measurement results can be easily performed.

(Other embodiments)
As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention.
Either the acquisition of the discharge determination threshold _Sth by the threshold setting program 12 or the acquisition of the initial voltage V0 by the initial voltage acquisition program 7 may be performed first. That is, the order of steps S1 and S2 in FIG. Either the mask process or the absolute value process by the discharge number calculation program 9 may be performed first. That is, the order of steps S8 and S9 in FIG.

  Mask processing and absolute value processing may be omitted. In that case, the discharge count calculation program 9 may count the number of occurrences of partial discharge using the partial discharge signal output from the partial discharge signal observation circuit 11. In the mask processing by the discharge number calculation program 9, a period near the peak of the impulse voltage (applied voltage waveform) (a predetermined period around the time t2 in FIG. 3) may be set as the specified time zone. Even in this case, the influence of noise at the rise and fall of the impulse voltage can be eliminated. Further, when it is sufficient to eliminate the influence of noise at the time of start-up that is considered to have a relatively large influence, the following may be performed. That is, the start point of the specified time zone is set to a time point after a predetermined time has elapsed from the start of the rise of the impulse voltage (eg, time t1 in FIG. 3), and the end point of the specified time zone is set to an arbitrary time point after the vicinity of the peak of the impulse voltage. It is good.

The threshold setting program 12 may acquire the discharge determination threshold _Sth as follows. That is, the partial discharge signal is observed for a predetermined period by the partial discharge signal observation circuit 11 in a state where the application of the impulse voltage to the electric motor 2 is stopped. Then, the discharge determination threshold value S _th is determined based on the maximum value of the partial discharge signal observed during the predetermined period. For example, a value obtained by adding a predetermined margin to the maximum value may be acquired as the discharge determination threshold value _Sth . In general, the partial discharge signal output from the partial discharge detection device 4 is weak, and is easily affected by noise. If the discharge determination threshold value _Sth is set as described above, there is an effect that the number of partial discharges can be accurately counted without being affected by such noise.

Step S13 in FIG. 2 etc. (comparison between command voltage Va and the upper limit value _{V max),} (compared to command voltage Va and the lower limit value _{V min)} Step T2 in FIG. 7 and the like may be provided as necessary.
The measurement control devices 5 and 22 are not limited to a configuration based on a personal computer, and may be configured as a dedicated device for controlling partial discharge measurement, for example.
These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  In the drawings, 1 and 21 are partial discharge measurement systems, 2 is an electric motor (measurement object), 3 is an impulse power supply (impulse voltage application means), 4 is a partial discharge detection device (partial discharge detection means), and 6 is a voltage control program. (Impulse voltage control means), 7 is an initial voltage acquisition program (rough voltage value input means), 8 is an applied voltage waveform observation circuit (applied voltage waveform observation means), 9 is a discharge frequency calculation program (partial discharge frequency counting means), 10 is a voltage value calculation program (voltage value calculation means), 12 is a threshold setting program (threshold setting means), 23 is a repetition count control program (repetitive execution control means), and 24 is a data storage device (data recording means). ).

Claims (12)

Impulse voltage applying means for generating a plurality of impulse voltages and applying them to the measurement object;
Impulse voltage control means for controlling the impulse voltage application means;
A partial discharge number counting means for counting the number of occurrences of the partial discharge based on a detection signal output from a partial discharge detection means for detecting a partial discharge in the measurement object;
Voltage value calculation means for calculating a voltage value applied to the measurement object,
The impulse voltage control means controls the impulse voltage application means so that a specified number of impulse voltages having the same peak value are applied to the measurement object,
The partial discharge number counting means counts the number of occurrences of the partial discharge every time a specified number of impulse voltages are applied to the measurement object,
The impulse voltage control means is configured to apply the impulse voltage according to a repetitive pattern in which a peak value of the impulse voltage is increased stepwise every time the specified number of impulse voltages are applied to the measurement object. The application means is controlled, and when the partial discharge number counting means first counts a partial discharge more than a specified number of times, the voltage value calculated by the voltage value calculation means is determined as a partial discharge start voltage, Controlling the impulse voltage application means to stop the application of the impulse voltage,
The impulse voltage controller further stops application of the impulse voltage and then applies the specified number of impulse voltages from the state where the partial discharge more than the specified number is counted by the partial discharge number counting unit. Controlling the impulse voltage application means so that an impulse voltage according to a repetitive pattern for gradually reducing the peak value of the impulse voltage is applied to the measurement object;
The repetitive impulse voltage characterized in that the voltage value calculated by the voltage value calculating means is determined as a partial discharge extinction voltage when the partial discharge number counting means first counts less than a specified number of partial discharges. Partial discharge measurement system. An applied voltage waveform observing means for observing a voltage waveform applied to the measurement object;
2. The partial discharge number counting unit is configured to count a partial discharge generated in a count effective period determined based on the voltage waveform observed by the applied voltage waveform observation unit. Partial discharge measurement system with repeated impulse voltage.   The partial discharge number counting means performs absolute value processing on the detection signal, and counts the number of occurrences of the partial discharge based on the detection signal after the absolute value processing is performed. Item 3. A partial discharge measurement system using a repetitive impulse voltage according to Item 1 or 2. The partial discharge number counting means compares the detection signal with a threshold value, and counts the occurrence of partial discharge when the detection signal exceeds the threshold value,
Threshold value setting means is provided for measuring the detection signal output in a state where the application of the impulse voltage by the impulse voltage application means is stopped and setting the threshold value based on the measured detection signal. The partial discharge measurement system using a repetitive impulse voltage according to any one of claims 1 to 3. An approximate voltage value input means for inputting a partial discharge start approximate voltage value which is an approximate value of the partial discharge start voltage of the measurement object;
5. The partial discharge by the repetitive impulse voltage according to claim 1, wherein the impulse voltage control unit sets a peak value of the impulse voltage based on a partial discharge start approximate voltage value. 6. Measuring system. Repetitive execution control means for repeatedly performing the determination of the voltage a plurality of times;
Data recording means for recording the voltage value calculated by the voltage value calculating means and the determination result of the voltage;
The partial discharge measurement system using a repetitive impulse voltage according to claim 1. Apply a specified number of impulse voltages with the same peak value to the measurement object,
Each time the specified number of impulse voltages are applied, the number of occurrences of the partial discharge is counted based on the detection signal output from the partial discharge detection means for detecting the partial discharge in the measurement object,
Applying an impulse voltage according to a repetitive pattern in which a peak value of the impulse voltage is increased stepwise each time the specified number of impulse voltages are applied to the measurement object;
First, when the partial discharge more than the specified number of times is counted, the voltage value applied to the measurement object is determined as the partial discharge start voltage, and the application of the impulse voltage is stopped.
After the application of the impulse voltage is stopped, a repetition pattern in which the peak value of the impulse voltage is lowered step by step every time the specified number of impulse voltages are applied from the state where the partial discharge is counted a predetermined number of times or more. Applying an impulse voltage to the object to be measured;
A partial discharge measurement method using a repetitive impulse voltage, wherein a voltage value applied to the object to be measured is determined as a partial discharge extinction voltage when partial discharges less than a specified number of times are first counted.   8. The partial discharge measuring method using a repetitive impulse voltage according to claim 7, wherein a partial discharge generated in a counting valid period determined based on a voltage waveform applied to the measurement object is counted. Perform absolute value processing on the detection signal,
9. The partial discharge measurement method using a repetitive impulse voltage according to claim 7 or 8, wherein the number of occurrences of the partial discharge is counted based on a detection signal after the absolute value processing is performed. Measure the detection signal output in a state where the application of the impulse voltage is stopped, set a threshold based on the measured detection signal,
10. The detection signal and the threshold value are compared, and occurrence of partial discharge is counted when the detection signal exceeds the threshold value. Partial discharge measurement method using repetitive impulse voltage. Enter a partial discharge start approximate voltage value that is an approximate value of the partial discharge start voltage of the measurement object,
The partial discharge measuring method using a repetitive impulse voltage according to any one of claims 7 to 10, wherein a peak value of the impulse voltage is set based on the partial discharge start approximate voltage value. The determination of the partial discharge start voltage or the determination of the partial discharge extinction voltage is repeatedly performed a plurality of times,
8. The partial discharge measurement method using a repetitive impulse voltage according to claim 7, wherein a voltage value applied to the measurement object is recorded.

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