JP4258386B2 - Insulation diagnostic device - Google Patents

Description

  The present invention relates to an insulation diagnosis apparatus, and more particularly to an insulation diagnosis apparatus suitable for determining an insulation deterioration tendency of electrical equipment such as a cable in a power system.

  Insulation deterioration of electrical equipment progresses with time, and often leads to a ground fault or a short-circuit accident. The progress mechanism of insulation deterioration is complicated, but the following two cases of modes are generally used.

  First, in the first case, current starts to leak from scratches and deteriorated parts of the cable sheathing and conductor support insulator, and damage and deterioration develop due to heat, pressure, ions, etc. generated by the leakage current, and the leakage current increases. This is the case.

  The other case is a case found in cables and the like, in which water penetrates into the insulator in a tree shape, causing dielectric breakdown at a stretch, and then recovering insulation.

  The latter is said to be an intermittent arc light ground fault and is difficult to detect because the phenomenon ends in a short time and is not reproducible.

  However, recent electrical equipment has a demand for technology for detecting an intermittent arc optical ground fault current in a live line state and a demand for a predictive diagnosis technology that can be scheduled for a planned equipment stoppage.

  Conventionally, a switchgear is provided between the neutral point of the ground voltage transformer (hereinafter abbreviated as GPT) and the ground, and is closed during normal operation, and is opened during diagnosis of insulation deterioration. DC voltage was applied, the leakage current from the electrical equipment to the ground was measured, and if the result exceeded a predetermined reference value, the electrical equipment was stopped and the insulation deterioration of the power line was individually tested. . However, some cables measured with this device and judged to be abnormal can be used without any problem in actual use, or some cables may be abnormal in actual use even if judged normal. This is because the measurement is carried out with a direct current, and the actual use is due to the difference in conditions of use with an alternating voltage and the slight difference in applied voltage. Even if the measurement is carried out with the same AC voltage as in actual use, the test apparatus such as a power source becomes large and zero phase monitoring is required.

  Further, in (Patent Document 1), a ground fault signal is extracted by detecting each of the reference line voltage signal and the other two-phase line voltage signals and zero-phase current, and the ground fault phase is determined from the phase. Moreover, although the fault line is judged by the zero-phase current, the intermittent arc light ground fault is difficult to detect because the duration is short, and the ground fault cannot be detected and the fault line cannot be judged.

  In (Patent Document 2), since the zero-phase voltage, zero-phase current, and line voltage are input, it is possible to determine the deteriorated phase and identify the fault line even in the case of an intermittent arc light ground fault. In some cases, the weak current due to the fault was detected, and it was mistakenly determined as an intermittent arc light ground fault or an accident line.

JP-A-4-42726 JP-A-6-300807

  As described above, in the conventional technique, it is necessary to inspect the insulation deterioration by stopping the power equipment in the actual use state, and the inspection result is unreliable, and the ground fault detection at the time of the intermittent arc light ground fault and I hated it was difficult to judge the accident line.

  The object of the present invention is to provide an insulation diagnostic device capable of identifying the occurrence of a ground fault and an accident line at the time of occurrence of an intermittent arc optical ground fault as well as being able to diagnose insulation deterioration without stopping the power equipment in actual use. There is to do.

  The present invention is an insulation diagnostic apparatus for diagnosing insulation of an electric workpiece by detecting line voltage, zero phase voltage, and zero phase current of a power system, and includes an arithmetic processing unit that calculates an intermittent arc light ground fault, It is characterized in that the fault line can be identified from the output part from a remote place by specifying the fault line from the product sum of the peak values of the phase current and the zero phase voltage.

  As described above, according to the present invention, it is possible to diagnose insulation deterioration without stopping power equipment in actual use, and it is possible to identify the occurrence of a ground fault and an accident line when an intermittent arc light ground fault occurs. Therefore, it has the effect of preventing serious accidents.

  A schematic structure of an insulation diagnostic apparatus to which the present invention is applied will be described with reference to FIG.

  FIG. 1 shows the configuration of the insulation diagnostic apparatus. A signal is input from the outside by the input unit 1, the arithmetic processing is performed by the CPU 3, and the input signal and the arithmetic result are stored in the memory 4. In addition, the display unit 5 can display calculation results and alarms, and the output unit 6 can output the calculation results and alarm signals to the outside.

FIG. 2 shows a high-voltage distribution system facility equipped with an insulation diagnostic device and a remote monitoring field monitoring device. The high-voltage distribution system facility shown in the figure includes a circuit breaker 8 connected to a transformer 7 and The bus 15 is connected, a plurality of feeder circuit breakers 9 to 12 drawn from the bus 15, a grounding transformer 13, and zero-phase current transformers 50 to 53 arranged for each phase. In order to detect insulation deterioration in these high-voltage distribution system facilities, the zero-phase current I ₀ is extracted from the zero-phase current transformers 50 to 53, the line voltage and the zero-phase voltage are extracted from the grounding transformer 13 and input to the insulation diagnostic device 14. is doing. Further outputs the detection result to the site monitoring apparatus 16 of the upper, Web terminal end 18 mag in situ monitoring device 16 itself, has a configuration that can transmit information to a remote location.

Insulation diagnostic device 14 according to an embodiment of the present invention provides zero-phase voltage V0 and line voltages V1-2, V2-3, and V3-1 from ground transformer 13 to any one of zero-phase current transformers 51-54. One of the zero-phase currents I0 is taken in as a signal. As shown in FIG. 3, the processing content is obtained by converting the high-frequency voltage of the zero-phase voltage V 0 of the grounding transformer 13 with the PEAK-HOLD 20, and calculating the effective value and comparing the set value with the effective value / setting value processing unit 21. When the set value is exceeded, the line voltages V1-2, V2-3 and V3-1 are subjected to phase shift conversion by the phase shift processing units 36 to 38, and the phase voltage (R phase, The sum of products with the S-phase and T-phase voltages is calculated by the product / sum processing units 26 to 28, then the maximum value is calculated by the maximum value processing unit 29, and the results are displayed by phase on the display units 33 to 35. PEAK-HOLD operation unit, the line voltage V1-2, V2-3, converted to V3-1 in phase voltage shifts the phase 30 degrees phase shift processing unit 36 to 38, Ri falling detection processing unit 22 The fall of the phase voltage is detected at ˜24, and the PEAK-HOLD is reset by a signal obtained by ORing the result by the OR processing unit 25. The reason for resetting PEAK-HOLD at the fall after the conversion to phase voltage is that the calculation result (the product-sum operation of the phase voltage and PEAK-HOLD value) is the maximum sensitivity, even before the fall of the phase voltage. It is because a result falls.

  On the other hand, the effective value calculation and the settling value comparison calculation result in the effective value / setting value processing unit 21 are compared with the R-phase, S-phase, and T-phase voltages and the phase region detection processing units 39 to 41 to compare and calculate the phase region. The signal ORed by the OR processing unit 42 (for example, R phase) coincides with the region for phase discrimination shown in FIG. 6 (the R phase in the shaded area), and the PEAK-HOLD of the zero phase voltage at the timer processing unit 43. When the moving average maximum value for 5 cycles exceeds the set value, the 64K operation processing unit 44 operates 64K.

  FIG. 7 shows a calculation example of the timer. When the zero phase waveform is generated as shown in the figure, the zero phase peak value is 30 V at the maximum, but the moving average maximum value for 5 cycles of the zero phase waveform is 24 V, and the zero phase moving average maximum value per second is 24V. By using the moving average maximum value for five cycles as a determination material, erroneous determination due to noise or the like can be prevented. In addition, the settling value of the timer is set to 1 second, focusing on the fact that the occurrence frequency of the intermittent arc light ground fault is less than 0.1 seconds to 0.5 seconds, and it does not occur for more than 5 seconds. Yes. Therefore, every time 1 second elapses, the zero phase peak value, the zero phase moving average maximum value, and the zero phase moving average maximum value per second are reset.

When the above calculation is performed, a high-frequency zero-phase voltage generated during an intermittent arc light ground fault can be reliably detected, and a 64K (intermittent ground fault overvoltage relay ) can be operated.

  Further, the high-frequency component of any one of the zero-phase currents is converted by PEAK-HOLD 45 into the zero-phase current transformers 50 to 53 shown in FIG. 2, and the result and the zero-phase voltage calculated by PEAK-HOLD 20 are summed. If the result is +, the AND processing unit 47 performs an AND operation. If 64K of the 64K operation processing unit 44 is operating, the accident line display unit 48 displays the accident line. If the result of the product-sum processing unit 46 is +, the fault line can be identified because the current flows toward the circuit at the fault point during a ground fault, so the zero-phase current and zero-phase voltage at the fault point are the same. Since the zero-phase current and zero-phase voltage are in opposite phases on a line that has a phase but no accident point, it is possible to determine whether the fault point is included or not by taking the product sum of the zero-phase voltage and zero-phase current. . Therefore, if the above calculation is performed, it can be reliably determined whether or not there is an accident line at the time of an intermittent arc light ground fault.

  Further, the output unit 6 shown in FIG. 1 outputs the measurement value, the accident line, the determination result, and the alarm information stored in the memory 4 to an external device such as a remote monitoring field monitoring device 16 for measurement even in a remote place. Values, accident lines, judgment results, and alarm information can be referenced.

  FIG. 4 shows an example of the configuration of an electrical facility provided with an insulation diagnostic device and a remote monitoring site monitoring device. The difference from FIG. 2 is that the connection configuration of the electrical equipment and the insulation monitoring device is different. In FIG. 2, there is one insulation diagnostic device for each feeder, whereas in FIG. It has become one.

An insulation diagnostic apparatus 14 'according to an embodiment of the present invention is configured to output a zero-phase voltage and a line voltage from a ground transformer 13 and a plurality of zero-phase voltages in a non-grounded high-voltage distribution system facility as shown in FIG. The zero-phase currents I ₀ 1 to I ₀ 4 detected from the current transformers 50 to 53 are taken in as signals.

  FIG. 5 shows a functional block diagram of the insulation diagnostic device 14 ′. The difference from FIG. 3 is that there are a plurality of zero-phase current inputs. Accordingly, PEAK-HOLD 85-88, product-sum processing units 89-92, AND processing units 93-96, and fault line display units 97-100. Are prepared for the zero-phase current input circuit, and a plurality of fault lines can be determined simultaneously.

As shown in FIG. 5, the processing contents of the insulation diagnostic device 14 'according to one embodiment of the present invention are obtained by converting the high-frequency voltage of the zero-phase voltage V0 of the grounding transformer 13 with the PWAK-HOLD 60, and obtaining the effective value and the settling value. The processing unit 61 performs an effective value calculation and a comparison calculation with a set value. When the set value is exceeded, the line voltages V1-2, V2-3, and V3-1 are phase-shifted by the phase shift processing units 76 to 78. Here, the product sum with the phase voltage (R phase, S phase, T phase voltage) subjected to phase shift conversion is calculated by the product / sum processing units 66 to 68, and then the maximum value is calculated by the maximum value processing unit 69. The result is ANDed with the 64K operation calculation result by the AND processing units 70 to 72, and the result is displayed for each phase on the display units 73 to 75. The PEAK-HOLD calculation unit shifts the line pressures V1-2, V2-3, and V3-1 to phase voltages by shifting the phase by 30 degrees by the phase shift processing units 76 to 78, and then falls detection processing units 62 to The fall of the phase voltage is detected at 64, and PEAK-HOLD is reset by a signal obtained by ORing the result by the OR processing unit 65. The reason for resetting PEAK-HOLD at the falling edge is the same as that explained in the insulation diagnostic apparatus 14.

  On the other hand, the result of comparison between the effective value calculation and the settling value in the effective value / setting value processing unit 61 is compared with the phase region in the R-phase, S-phase, and T-phase voltages and the phase region detection processing units 79 to 81. The signal calculated by the OR processing unit 82 and the result shown in FIG. 6 coincide with the result shown in FIG. 6, and the moving average maximum value for the PEAK-HOLD value 5 periods of the zero-phase voltage is set to the set value in the timer processing unit 83. If it exceeds, 64K operation processing unit 84 is configured to operate 64K. The reason why the moving average maximum value for five periods of the PEAK-HOLD value of the zero-phase voltage is used as a judgment material and the settling value are the same as those of the insulation diagnostic device 14.

  Further, the high-frequency components of the zero-phase current of each of the zero-phase current transformers 51 to 54 are converted by PEAK-HOLD 85 to 88, and the result and the zero-phase voltage calculated by PEAK-HOLD 60 are converted by product-sum processing units 89 to 92. When the sum of products is calculated and the result is +, AND processing is performed by the AND processing units 93 to 96. To do. If the result of the sum-of-products processing unit 89 to 92 is +, the reason why the fault line can be identified is that current flows toward the faulty line at the time of a ground fault. Zero-phase voltage is in phase, but there is no fault point on the line. Zero-phase current and zero-phase voltage are in opposite phase. Can be judged.

  Similarly to the insulation diagnosis device 14, the measurement value, the accident line, the determination result, and the alarm information stored in the memory 4 are output to an external device such as a remote monitoring field monitoring device 16, and the measurement value is also obtained at a remote location. , Accident line, judgment result, alarm information can be referred.

It is the block diagram which showed one Example of the insulation diagnostic apparatus of this invention. It is the figure which showed the structural example of the electrical equipment provided with the insulation diagnostic apparatus of one Example of this invention. It is a block diagram which shows the arithmetic processing in one Example of the insulation diagnostic apparatus of this invention. It is the figure which showed the structure of the electrical installation provided with the insulation diagnostic apparatus of the other Example of this invention. It is a block diagram which shows the arithmetic processing in the other Example of the insulation diagnostic apparatus of this invention. It is explanatory drawing of the operation | movement phase area | region in one Example of the insulation diagnostic apparatus of this invention. It is explanatory drawing of the example of a timer calculation in one Example of the insulation diagnostic apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Input part, 2 ... Power supply part, 3 ... CPU, 4 ... Memory, 5 ... Display part, 6 ... Output part, 7 ... Transformer, 8 ... Circuit breaker, 9-12 ... Feeder circuit breaker, 13 ... Grounding Transformer, 14 ... Insulation diagnostic device, 15 ... Busbar, 16 ... Field monitoring device, 19 ... Remote monitoring center, 21 ... Effective value / settling value processing unit, 36-38 ... Phase shift processing unit, 39-41 ... Phase region Detection processing unit, 43 ... timer processing unit, 44 ... 64K operation processing unit, 45 ... PEAK-HOLD, 46 ... product-sum processing unit, 47 ... AND processing unit, 51-54 ... zero-phase current transformer.

Claims (2)

A first PEAK-HOLD processing unit that takes in a zero-phase voltage from the grounding transformer as a signal and performs PEAK-HOLD processing on the high-frequency voltage of the zero-phase voltage, and one of a plurality of zero-phase current transformers A second PEAK-HOLD processing unit that takes in the zero-phase current as a signal and performs PEAK-HOLD processing on the high-frequency current of the zero-phase current;
An effective value / settling value processing unit that performs a comparison operation between the result of PEAK-HOLD processing by the first PEAK-HOLD processing unit and the effective value calculation and settling value of the high-frequency voltage of the zero-phase voltage;
A phase shift processing unit that performs phase shift conversion of the line voltage taken from the grounding transformer when the comparison operation with the set value in the effective value / set value processing unit is equal to or more than the set value;
When the phase shift processing unit shifts the phase of the line voltage and converts it to a phase voltage, a falling detection processing unit detects the falling of the phase voltage;
A first OR processing unit that ORs the detection result in the falling detection processing unit and resets the PEAK-HOLD by the ORed signal;
A phase region detection processing unit that compares and calculates the result of the effective value calculation and the settling value comparison calculation in the effective value / setting value processing unit, and the phase region of the phase voltage;
A second OR processing unit that performs an OR process on the result of the calculation in the phase region detection processing unit;
When the signal subjected to OR processing in the second OR processing unit matches the phase region of the phase voltage, and the moving average maximum value for the PEAK-HOLD value of 5 periods of the zero phase voltage exceeds the set value, A 64K operation processing unit for operating 64K;
A product / sum processing unit that performs a product-sum operation on the processing result in the first PEAK-HOLD processing unit and the processing result in the second PEAK-HOLD processing unit;
An accident line display unit that displays an accident line under an AND condition that the result of calculation in the product / sum processing unit is positive and 64K is operating in the 64K operation processing unit;
An insulation diagnostic apparatus comprising:   A timer processing unit for determining that the moving average maximum value for five periods of the PEAK-HOLD value of the zero-phase voltage has exceeded the settling value, and setting the time limit of the operation timer of the timer processing unit to 0.1 to 1.0. The insulation diagnostic apparatus according to claim 1, wherein the insulation diagnosis apparatus is set to seconds.

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