JPH04368415A - Method of detecting insulation deterioration of power system and devices for detecting, discriminating, and monitoring insulation deterioration, grounding generator, and resonance frequency measuring system - Google Patents

Abstract

PURPOSE:To reduce the influence of a residual component, noise, etc., so as to detect the insulation deterioration of a three-phase power system with high sensitivity by detecting zero-phase voltages in bands except the resonance frequency of the power system. CONSTITUTION:A sensor device 20 is constituted of a V0 sensor using a grounding transformer composed of a star-connected primary winding 22 connected to a three-phase bus 3 and delta- connected secondary winding 23 and a slave station 21 is connected to a host station through a communication line 33. The voltage V0 detected across both ends of a current-limiting resistance 24 is inputted to an amplifier 25 by which the voltage is converted into a voltage signal which is suitable for signal processing. A V0 signal generated when deterioration occurs contains many frequency components other than a power supply frequency and frequencies of the natural-number multiple of the frequency and, the frequency components become larger as their frequencies become lower. Therefore, when the power supply frequency component which contains the largest amount of a residual component is eliminated from the output signal of the amplifier 24 by means of a 5-Hz notch filter 26 and system noise is removed by means of a 1kHz low-pass filter 27, only the small V0 signal which becomes relatively large when deterioration occurs can be extracted with high accuracy.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method and apparatus for detecting insulation deterioration in a power system, and particularly to a method and apparatus for detecting insulation deterioration in a power distribution system, and particularly for detecting insulation deterioration in a power distribution system and determining the section where the deterioration occurs with high sensitivity. Detection method and device.

0002

2. Description of the Related Art Generally, power systems are provided with a protection device that detects ground faults or short circuit failures and stops power transmission. For example, in the case of power distribution systems, such protection devices have a tree-like system configuration and are installed at the base of the system, so once a failure occurs and the protection device is activated, it can cause a widespread power outage. I will invite you. For this reason, regular equipment replacement and visual inspections are carried out to prevent breakdowns, but in power distribution systems, much of the equipment is located over a wide area and is exposed to various environments. Due to this and the increasing concealment of equipment, the rate of preventing failures was low considering the amount of effort involved.

[0003] Most of the failures that occur in actual distribution lines are
This is a ground fault, and this type of fault is often accompanied by some kind of precursor ground fault signal (hereinafter referred to as a degradation signal). Therefore,
Techniques have been proposed to detect this deterioration signal and detect the section where it occurs, thereby updating equipment in a focused manner and preventing failures.

[0004] An example of this prior art is ``Basic Study on a Method for Detecting Deteriorated Sections of Insulation in a Power Distribution System'' (Nagayama, Aoyagi et al., 1990 National Conference of the Electric Power and Energy Division of the Institute of Electrical Engineers of Japan).

[0005]

[Problems to be Solved by the Invention] With conventional technology, it is difficult to distinguish between signals generated by the resonant frequency of the power system, residual components, and system noise, and signals generated by insulation deterioration, and high-sensitivity detection of insulation deterioration is required. was difficult.

Further, no consideration has been given to the method of displaying the output after insulation deterioration has been detected.

Furthermore, no particular device for testing the occurrence of insulation deterioration has been devised.

An object of the present invention is to reduce the influence of these residual components and system noise, and to detect and determine the occurrence of insulation deterioration in a power system and the area thereof with high sensitivity. Another object is to provide a display that allows the operator to obtain information regarding deterioration at a glance. Another object of the present invention is to provide an insulation deterioration occurrence test device that can improve test efficiency.

[0009]

[Means for Solving the Problems] The above object is to reduce the occurrence of insulation deterioration by reducing the magnitude of the generation level of zero-sequence voltage and/or zero-sequence current in a band other than the resonant frequency of the three-phase power system. This is achieved by being detected using

[0010] The above object is also achieved by determining the insulation deterioration occurrence section using the phase difference spectrum between the zero-sequence voltage and the zero-sequence current in a band excluding the resonance frequency of the three-phase power system. is also achieved.

[0011] The above object is to prevent the occurrence of insulation deterioration from occurring as a zero-sequence voltage and/or zero-sequence current in a band other than the resonant frequency of the three-phase power system, using the low frequency component of the zero-sequence voltage as a trigger. This can also be achieved by being detected using the magnitude of the level.

[0012] The above object also provides that the zero-sequence voltage and/or zero-sequence current is a zero-sequence voltage and/or zero-sequence current in a band excluding the power supply frequency and the resonant frequency of the three-phase power system. It is also achieved by being and being done.

[0013] The above object also aims to prevent the occurrence of insulation deterioration.
Insulation that is detected using the generation level of zero-sequence voltage and/or zero-sequence current in a band other than the resonant frequency of the three-phase power system, or triggered by the low frequency component of zero-sequence voltage. The above object is also characterized in that the occurrence of deterioration is detected using the magnitude of the generation level of zero-sequence voltage and/or zero-sequence current in a band other than the resonant frequency of the three-phase power system. The zero-sequence voltage and/or zero-sequence current can also be achieved by being a zero-sequence voltage and/or zero-sequence current in a band excluding the power supply frequency and the resonant frequency of the three-phase power system.

[0014] The above object also aims to prevent the occurrence of insulation deterioration.
Insulation that is detected using the generation level of zero-sequence voltage and/or zero-sequence current in a band other than the resonant frequency of the three-phase power system, or triggered by the low frequency component of zero-sequence voltage. The above objective is also to detect the occurrence of deterioration using the magnitude of the generation level of zero-sequence voltage and/or zero-sequence current in a band other than the resonant frequency of the three-phase power system. The phase voltage and/or zero-sequence current is a zero-sequence voltage and/or zero-sequence current in a band excluding the power supply frequency, its natural number multiple frequency, and the resonant frequency of the three-phase power system. is also achieved.

The above object also provides a method in which the insulation deterioration occurrence section is determined using a phase difference spectrum between the zero-sequence voltage and the zero-sequence current in a band excluding the resonance frequency of the three-phase power system; Alternatively, using the low frequency component of the zero-sequence voltage as a trigger, the section where insulation deterioration occurs is determined using the phase difference spectrum between the zero-sequence voltage and the zero-sequence current in a band other than the resonant frequency of the three-phase power system. The above purpose is also achieved by the fact that zero-sequence voltage and zero-sequence current are zero-sequence voltage and zero-sequence current in a band excluding the power supply frequency and the resonant frequency of the three-phase power system. is also achieved.

[0016] The above object is also achieved by determining the section where insulation deterioration occurs using the phase difference spectrum pattern between the zero-sequence voltage and the zero-sequence current in a band excluding the resonant frequency of the three-phase power system. or using the phase difference spectrum between the zero-sequence voltage and the zero-sequence current in a band other than the resonant frequency of the three-phase power system, where the insulation deterioration occurs using the low-frequency component of the zero-sequence voltage as a trigger. The above purpose is also that zero-sequence voltage and zero-sequence current refer to zero-sequence voltage and zero-sequence current in a band excluding the power supply frequency, its natural number multiples, and the resonant frequency of the three-phase power system. This is also achieved by voltage and zero-sequence current.

The above purpose is also to find the magnitude of the generation level of zero-sequence voltage and/or zero-sequence current in a band excluding the power supply frequency, and then to calculate the magnitude of the zero-sequence voltage in the frequency band exceeding the power supply frequency. This can also be achieved by detecting the occurrence of insulation deterioration using a frequency component as a trigger.

The above purpose is also to find the magnitude of the generation level of zero-sequence voltage and/or zero-sequence current in a band excluding the power supply frequency, and then to calculate the magnitude of the zero-sequence voltage generation level in the frequency band exceeding the power supply frequency. When the occurrence of insulation deterioration is detected using a frequency component as a trigger, the zero-sequence voltage and/or zero-sequence current is a zero-sequence voltage in a band excluding the power supply frequency and its natural number multiple frequencies. Alternatively, this can also be achieved by using zero-sequence current.

The above purpose is also to obtain the phase difference spectrum pattern of the zero-sequence voltage and zero-sequence current in a band excluding the power supply frequency, and then to calculate the low frequency component of the zero-sequence voltage in the frequency band exceeding the power supply frequency. This can also be achieved by determining the section where insulation deterioration occurs as a trigger.

The above purpose is also to obtain the phase difference spectrum of the zero-sequence voltage and zero-sequence current in a band excluding the power supply frequency, and then to trigger the low frequency component of the zero-sequence voltage in the frequency band exceeding the power supply frequency. In determining the section where insulation deterioration occurs, the zero-sequence voltage and zero-sequence current are zero-sequence voltage and zero-sequence current in a band excluding the power supply frequency and its natural number multiple frequencies. It is also achieved by

[0021] The above purpose is also to find the magnitude of the generation level of zero-sequence voltage and/or zero-sequence current in a band excluding the power supply frequency, and then to calculate the magnitude of the generation level of zero-sequence voltage and/or zero-sequence current in a frequency band exceeding the power supply frequency. The occurrence of insulation deterioration is detected using a low frequency component as a trigger, or the above zero-sequence voltage and/or zero-sequence current is a zero-sequence voltage in a band excluding the power supply frequency and its natural number multiple frequencies. , and/or the zero-sequence current, or find the phase difference spectrum of the zero-sequence voltage and zero-sequence current in a band excluding the power supply frequency, and then calculate the low frequency of the zero-sequence voltage in the frequency band exceeding the power supply frequency. determining the insulation deterioration occurrence section using the component as a trigger;
Or, the above zero-sequence voltage and zero-sequence current are the power supply frequency,
The zero-sequence voltage and zero-sequence current are in a band excluding natural number multiples of the frequency, and the low frequency component of the zero-sequence voltage is less than twice the power supply frequency. be done.

The above object is also such that the phase average value θ of the zero-sequence current with respect to the zero-sequence voltage in a band excluding the power supply frequency (where |θ|≦180°) is -90°+θ1>θ>−90 °−θ2 (θ1, θ2
: constant ≦90°), it is determined that insulation deterioration has occurred on the load side, and -90°
+θ1<θ<180° or -90°−θ2>θ>
If it is −180°, this can also be achieved by determining that insulation deterioration has occurred on the power supply side.

The above object is also such that the phase average value θ of the zero-sequence current with respect to the zero-sequence voltage in the band excluding the power supply frequency (however, |θ|≦180°) is -90°+θ1>θ>-90 °−θ2 (θ1, θ2
: constant ≦90°), it is determined that insulation deterioration has occurred on the load side, and -90°
+θ1<θ<180° or -90°−θ2>θ>
-180°, it is determined that insulation deterioration has occurred on the power supply side, and the phase average value θ of the zero-sequence current with respect to the above-mentioned zero-sequence voltage
can also be achieved by being the phase average value θ of the zero-sequence current with respect to the zero-sequence voltage in a band excluding the power supply frequency and its natural number multiple frequencies.

The above object can also be achieved by satisfying θ1<θ2 in the above-mentioned means for solving the problem.

[0025] Also, in the above-mentioned means for solving the above-mentioned object, the phase average value θ of the zero-sequence current is a phase average value in a low frequency region up to frequencies that are natural number multiples of the power supply frequency. It is also achieved by The above problem can also be achieved by, in the means for solving the problem, the natural number multiple frequency of the power supply frequency being four times the power supply frequency.

The above object can also be achieved by determining the occurrence of insulation deterioration from the power source side of the power system in the means for solving the problem.

[0027] The above object also includes a first electrode connected to the power distribution line, a second electrode facing the first electrode and connected to the ground potential, and a second electrode connected to the power distribution line. This is also accomplished by providing a ground fault generating device comprising means for controlling the gap length between the electrode and the second electrode.

[0028] The above object can also be achieved by, in the ground fault generating device, at least one of the first electrode and the second electrode containing an arc-resistant metal.

[0029] The above object can also be achieved by providing the above-mentioned ground fault generating device and means for measuring a resonant frequency specific to the power system.

[0030] The above object also provides a means for generating information for specifying insulation deteriorated sections of a three-phase power system, and a means for displaying at least a part of the three-phase power system diagram and the information for specifying the insulation deteriorated sections on the same screen. This can also be achieved by providing a display device for displaying information in the area. The above object also provides means for calculating the phase average value θ and absolute value of zero-sequence current with respect to zero-sequence voltage at at least one point in a three-phase power system, and a means for calculating the phase average value θ and absolute value of zero-sequence current with respect to zero-sequence voltage Information specifying the area where insulation deterioration occurs on the load side and/or power supply side within the two-dimensional coordinate area showing the relationship between This can also be achieved by providing a display device that simultaneously displays information corresponding to θ and the absolute value.

The above object is also the calculating means and the display device, wherein the calculating means calculates the phase average value θ and absolute value of the zero-sequence current for each zero-sequence voltage at a plurality of locations. and the display device is a display device that displays information corresponding to the phase average value θ and absolute value of the zero-sequence current with respect to the zero-sequence voltage at one of the plurality of locations. is also achieved.

The above object is also the calculating means and the display device, wherein the calculating means calculates the phase average value θ and absolute value of the zero-sequence current for each zero-sequence voltage at a plurality of locations. This can also be achieved by the display device being a display device that simultaneously displays information corresponding to the phase average value θ and the absolute value of the zero-sequence current with respect to the zero-sequence voltage at the plurality of locations. be done.

The above object also provides means for calculating the phase average value θ and absolute value of the zero-sequence current with respect to the zero-sequence voltage at at least one point in a three-phase power system, and The degree of progress of insulation deterioration corresponds to a plurality of mutually distinguishable regions according to the phase average value and absolute value, and the phase average value θ and absolute value of the zero-sequence current with respect to the zero-sequence voltage at the predetermined location. This can also be achieved by being equipped with a display device that simultaneously displays the information to be displayed.

The above object also provides a means for calculating the phase average value θ and absolute value of the zero-sequence current with respect to the zero-sequence voltage at at least one point in a three-phase power system, and The degree of progress of insulation deterioration corresponds to a plurality of mutually distinguishable regions according to the phase average value and absolute value, and the phase average value θ and absolute value of the zero-sequence current with respect to the zero-sequence voltage at the predetermined location. This can also be achieved by providing a display device that simultaneously displays the information that is displayed.

[0035]

[Operation] The mechanism of generation of a deterioration signal will be explained using as an example the occurrence of cracks in an insulator due to a large current during a lightning strike. first,
A crack in the insulator will not cause any abnormality in the insulation, but if it rains with salt etc. attached to the crack,
The dielectric strength decreases, a small discharge occurs, and a deterioration signal is observed. However, if the discharge continues for a certain amount of time, the water will evaporate due to the temperature rise in that area, and the state will temporarily return to normal. In this state, the duration of the deterioration current is short and its level is small, so the protection device does not operate and the occurrence of cracks remains unknown. As a result, the single discharge repeats again, eventually leading to a permanent failure. During this period, the duration of the discharge deterioration current is relatively long, and the protection device may operate, but when the power is retransmitted, the moisture has evaporated, making it extremely difficult to find the cause. Here, we have taken as an example the occurrence of cracks in insulators, but the same phenomenon occurs when trees or animals come into contact with animals. The inventors discovered that the deterioration signal associated with these phenomena has different characteristics from the residual components and system noise, and found that it is possible to use these characteristics to detect insulation deterioration and determine the area with high sensitivity. did it. One of the characteristics of this is that the spectrum of zero-sequence voltage and zero-sequence current that accompanies discontinuous phenomena such as discharge due to deterioration contains many components in addition to the power supply frequency and its natural number multiples, and especially the zero-sequence voltage The spectrum of is that the lower the frequency component, the larger the tendency. On the other hand, most of the residual components are the power supply frequency and its natural number multiple frequency components. In addition, it was found that system noise generated by switching on and off loads exists in a higher frequency band compared to degraded signals.

In the present invention, the occurrence of deterioration is first detected based on the zero-phase voltage generation level excluding the power supply frequency and high frequency components, which are largely affected by residual components and system noise. Next, the deterioration occurrence section is determined using the phase of the zero-sequence current and zero-sequence voltage in a band excluding frequencies that are natural number multiples of the power supply frequency.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a state in which an insulation deterioration detection device according to the present invention is installed in a three-phase power distribution system.

The power distribution system shown in the figure operates by a transformer 1 that transforms power supplied from an upper high voltage system into a distribution voltage, and a shutdown command from a protection device (not shown) connected to the transformer 1. A circuit breaker 2, a three-phase bus 3 connected to the circuit breaker 2, and a plurality of three-phase feeders 7, 8, 9 connected to the three-phase bus 3 via circuit breakers 4, 5, 6 (here 3 feeders). The insulation deterioration detection device installed in this power distribution system includes sensor devices 10A to 10C, 11A to 11C, and 12A to 12C installed at predetermined intervals on the three-phase feeders 7, 8, and 9, and these sensor devices. The slave stations 13A to 13C are connected to the respective sensor devices, and the output signals of the sensor devices are inputted and preprocessed.
, 14A to 14C, 15A to 15C and communication lines 16, 17, 1 that interconnect adjacent slave stations on the same feeder.
8, and a slave station 1 located closest to the power supply side of each feeder.
3A, 14A, and 15A, and a master station 19 serving as a determining means. It also includes a sensor device 20 and a slave station 21 that are attached to the three-phase bus 3 and whose output signals are connected to the master station 19 via the communication line 33.

FIG. 2 shows the configuration of the sensor device 20 and slave station 21.
Explain with reference to. In FIG. 2, the sensor device 20 is constituted by a V0 sensor using a grounding transformer including a star-connected primary winding 22 and a delta-connected secondary winding 23 connected to the three-phase bus 3. A neutral point of the primary winding 22 is grounded, and a current limiting resistor 24 is connected to one side of the delta connection. The slave station 21 includes an amplifier 25 whose input is V0 detected as the voltage across the current limiting resistor 24, and the amplifier 2.
5 connected to the output side respectively and the power supply frequency, e.g. 50
A notch filter 26 tuned to Hz, a low-pass filter 27 with a cutoff frequency of 1 kHz connected to the output side of the notch filter 26, and an AD converter 28 that converts the output of the low-pass filter 27 into a digital signal. , a low-pass filter 29 having a cutoff frequency of 90 Hz connected to the output side of the notch filter 26, a comparator 30 whose input is the output of the low-pass filter 29, and the comparator 30 and the A
It is configured to include a memory 31 connected to the output side of the D converter 28 and a communication terminal 32 connected to the output side of the memory 31. The communication terminal 32 connects the communication line 33 to the master station 19.
connected via.

Next, sensor devices 10A~ having the same configuration
10C, 11A to 11C, 12A to 12C and slave station 13
The configurations of A to 13C, 14A to 14C, and 15A to 15C will be described with reference to FIG. 3, taking the sensor device 10A and the slave station 13A as examples.

In FIG. 3, the sensor device 10A is comprised of an I0 sensor 34 coupled to a three-phase feeder 7. In FIG. The slave station 13A includes an amplifier 35 to which the output of the I0 sensor 34 is connected, a notch filter 36 connected to the output side of the amplifier 35 and tuned to a power frequency of 50 Hz, and an output side of the notch filter 36. connected to
A low-pass filter 37 having a cutoff frequency of 1 kHz, an AD converter 38 that converts the output of the low-pass filter 37 into a digital signal, a memory 39 connected to the output side of the AD converter 38, and the memory 39. The communication terminal 40 is connected to the output side of the communication terminal 40. The communication terminal 40 is connected to the master station 19 and the adjacent slave station 13B on the same feeder 7 via the communication line 16.

The sensor device and slave station configured as described above operate as follows. In FIG. 2, V0 detected as the voltage across the current limiting resistor 24 is input to the amplifier 25 and converted into a voltage signal suitable for signal processing. As mentioned above, the V0 signal generated at the time of deterioration includes many frequency components in addition to the power supply and its natural number multiple frequency, and the lower the frequency component, the larger the frequency component becomes. Therefore, from the output signal of amplifier 25,
The 50 Hz notch filter 26 removes the power frequency component with the largest residual component, and further removes the 1 kHz
By removing systematic noise with the low-pass filter 27, only the minute V0 signal that occurs relatively frequently during deterioration can be extracted with high accuracy. In particular, in the present invention, system noise increases due to the resonance of the inductance and capacitance of the system, and the resonance frequency is almost 1, considering the values of the inductance and capacitance of the general system.
It was discovered that the frequency was higher than 1 kHz, and a 1 kHz low-pass filter 27 was used. Here, the low-pass filter 27 is used as a filter, but a band-pass filter that removes only the resonance frequency band of the system may be used.

The output of the 1 kHz low-pass filter 27 is input to the AD converter 28, converted into a digital signal, and then repeatedly written into the memory 31. On the other hand, 50
The output of the Hz notch filter 26 is also input to a 90 Hz low-pass filter 29, and only components in a relatively low frequency band among the low frequency components characteristically generated due to deterioration are extracted. The extracted low frequency component is sent to comparator 3.
0 is compared with a preset reference value, and if it exceeds the reference value, it is determined that deterioration has occurred, a memory hold signal is output, and the V0 time data at that time is stored in the memory 31. Here, the lower the cutoff frequency of the low-pass filter 29 is set, the stronger it becomes against residual components and noise, but if it is set below the power supply frequency, the response to the occurrence of deterioration becomes poor and detection becomes difficult. On the other hand, if the cutoff frequency is set high, residual components and noise will cause malfunctions, and the risk of this is particularly high in a frequency range that is a natural number multiple of the power supply. In the present invention, the above points were experimentally discovered, and the cutoff frequency of the low-pass filter 29 was set to 90 Hz, which exceeds the power supply frequency and is less than twice the power supply frequency. Here, the reason why the cutoff frequency of the low-pass filter 27 is set to 1 kHz, which is higher than that of the low-pass filter 29, is that for the data in the memory 31, as will be described later, the residual frequency of the natural number multiple of the power supply is This is because the response to the deterioration phenomenon can be increased as much as possible without being affected by system noise, since it can be removed by the processing of the master station 19. The memory hold signal from the comparator 30 is transmitted to the master station 1.
9 to slave station 13A via communication lines 16, 17, and 18.
~13C, 14A~14C, and 15A~15C are also transmitted.

The operation of the slave station 13A in FIG. 3 is similar to that of the slave station 21 shown in FIG. 2, except for the memory hold signal generation operation.
The I0 time data at the time of occurrence of deterioration is held in the memory 39 by a memory hold signal from the master station 19. Slave stations 13B-13C, 14A-14C, 15
A to 15C operate similarly. V0, I0
When the time data is stored in the memory of each slave station, a signal indicating the occurrence of deterioration is again transmitted from the memory to the master station 19, and the deterioration section determination program of the master station 19 is activated.

The processing algorithm of the master station 19 will be explained based on FIG. First, in S1, the V0 time data of the slave station 21 and the slave stations 13A to 13C that have been transmitted are transmitted.
, 14A to 14C, and 15A to 15C, the phase of each I0 slave station with respect to V0 is determined for each of a plurality of frequencies. As a specific means, a digital filter or Fourier transform is used. Here, the multiple frequencies range from 0 to 4 times the power supply frequency.
Select a frequency between 200 Hz and 0 Hz, excluding the power source and its natural number multiple frequencies. The reason for using the 0 to 200 Hz band is that the components in this band become relatively large due to deterioration. Furthermore, the reason for excluding data on the power supply and its natural number multiple frequencies is that these components have a large residual influence. In S2, the average value of the phases at the plurality of frequencies determined in S1 is determined for each slave station. The average value of the determined phases is expressed as θ(i, j). Here, i and j in parentheses are feeder numbers, respectively. and slave station no. , and the slave stations 13A to 1
Taking 3C as an example, i=1 and will be expressed as j=1, 2, 3. Hereinafter, feeders 7, 8, and 9 will be referred to as feeder No. Call them 1, 2, 3.

In S5, first, θ(1, 1), that is, the phase average value of the slave station 13A is determined, and -160°≦θ(1,
1) If ≦-60° is not satisfied, it is determined that deterioration has occurred in another feeder, and after checking that it is not the final feeder in S9, return to S4, add 1 to i, and then θ
A determination of (2, 1) is made. In this way, even if you check all the way to the final feeder, -160°≦ θ(i
, 1) ≦ -60° is not satisfied, and if it is determined that deterioration has occurred in another feeder, it is determined that an erroneous activation has occurred, a message indicating that there is no abnormality is output in S10, and the process ends. On the other hand, −1
If 60°≦θ(1,1)≦−60° is satisfied, feeder No. 1, it is determined that deterioration has occurred, and S
Proceed to step 7 and start searching for a degraded section. -160 in S7
Check whether °≦θ(1,2)≦−60° holds true. If this condition is not satisfied, it is determined that deterioration has occurred in the power supply side section from the slave station 13B, that is, between the slave stations 13A and 13B, and in S11, the feeder No. and slave station no. is displayed and exits. On the other hand, if the above conditions are met, the slave station whose phase was checked in S7 is the feeder No. Check whether it is the terminal slave station of 1. In this case, since it is not a terminal slave station, the process returns to S6 and 1 is added to j, and then a determination is made regarding θ(1,3) in S7. Here, θ(
1, 3) satisfies the conditions, the load side section from slave station 13B, that is, feeder No. It is determined that deterioration has occurred in the end section of 1, the display is displayed in S12, and the process ends. Here, feeder No. Although the search for the degraded section No. 1 has been described, the same applies to other feeders.

[0047] Here, at S5 or S7 -160°
Based on Figure 5, we will explain why it is determined that deterioration has occurred in the feeder or load side section if ≦ θ (i, j) ≦ -60° holds, and in other feeders or power supply side sections if it does not hold. explain. Note that the representation in FIG. 5 is based on the literature (Nakayama: Protective Relay System, Denki Shoin).

FIG. 5 shows the flow of I0 in the grid when deterioration occurs.
50 represents the ground capacitance of the system. Reference numeral 51 represents a resistance on the primary side of the current-limiting resistance 24 connected to one side of the secondary winding 23 of the grounding transformer described in FIG. As shown in FIG. 5, when deterioration occurs at point F of the feeder 8, the ground charging currents Ic1 and Ic3 of the healthy feeders 7 and 9 pass through the three-phase bus 3 to the deterioration point F.
flows into. Further, the current In flowing through the neutral point of the primary winding 22 of the grounding transformer also flows into the deterioration point F. In the feeder where deterioration occurs, the ground charging current on the power supply side from the deterioration point F
Ic2' and the load-side ground charging current Ic2'' flow into the deterioration point F. Here, the increase in the neutral point voltage caused by the current In is V0, and the sign is determined as follows.

[0049]

[Math 1]

Here, Rn: value number 1 of the primary conversion resistance 51
If the code is determined as follows, in the feeder 8 of FIG.
A vector diagram of I0 flowing on both sides of the deterioration point can be expressed as shown in FIG. In FIG. 6, I0'
, I0'' are the I0 flowing through the feeder on the power supply side and the load side from the deterioration point, respectively, and I0N is the noise existing in the system and detection circuit.Here, I0'', I0
An example in which the magnitudes of N and Ic2'' are small is shown in an enlarged scale for convenience.

Here, the phase α of I0' with respect to V0 changes depending on the ratio of the absolute values of In and Ic1+Ic3+Ic2'. That is, the phase α is approximately the value of the primary conversion resistance 51.
It varies depending on Rn and the system ground capacitance Cs as shown in the following equation.

[0052]

[Math 2]

Here, ω: angular frequency In a general power distribution system, Rn is several 10 kΩ,
Cs is about 0.1 to 20 μF, and from Equation 2, the phase α is distributed around −160° to −90°. On the other hand, considering the case where a reactor is connected in parallel with the resistance value Rn or the influence of noise is large, α may be -90° or less, so this time we took a margin and set it to -160°. When °≦α≦−60° was established, it was determined that deterioration occurred in the load side section of the feeder. Here, the reason why the range of α is made asymmetric with respect to −90° and the range from 0° to −90° is narrowed to 30° as shown in FIG. 7 is as follows. In general, the noise I0
Since N excludes the power supply and its natural number multiple frequencies, it becomes broadband random noise, and its phase is distributed around 0° by taking the average of multiple frequencies. Therefore, it is relatively susceptible to noise.
This is because the risk of erroneous determination can be reduced by determining the phase in a region away from around 0°.

On the other hand, the phase β of I0″ is the noise I0N
If the influence of I is small, it will be 90°, but the noise I
When the influence of 0N becomes large, the distribution will be around 0° to 90°. Here, if the phase range in which it is determined that deterioration has occurred in other feeders is made as wide as possible, it will be determined that it is an erroneous activation and a message indicating that there is no abnormality will be output at S10, which will prevent erroneous determinations due to other external noises. This eliminates noise, making the system resistant to noise. On the other hand, if it is determined that deterioration has occurred in that feeder and the search routine for the deterioration section is entered, the deterioration section can be reliably discovered by widening the phase range in which it is determined that deterioration has occurred in the power supply side section as much as possible. . For the above reasons, as shown in Figure 7, −160° ≦
For all phases other than θ(i,j)≦−60°, it is determined that deterioration occurs in other feeders or in the power supply side section.

[0055] Figures 8 and 9 show examples of the results of processing data stored in the power supply side slave station and load side slave station at the master station from the point of deterioration, respectively, when deterioration occurs in actual power distribution equipment. . The power frequency is 50 Hz. In each figure, (a) and (b) are time data and spectra of V0 and I0, respectively. The time data in both figures contains a lot of noise, and only slight waveform changes can be seen in the V0 data. On the other hand, as explained above, in the spectrum, many frequency components are generated in addition to the power supply and its natural number multiple frequency components that exist even in a healthy state, and in particular, in the spectrum of V0, the lower the frequency component, the larger the frequency component. It shows a tendency to Figure 8(c), 9
(c) shows the phase spectrum of I0 with respect to V0. From each phase spectrum, the phases at multiple frequencies excluding the power supply and its natural number multiple frequencies are determined, and their average values are respectively θ(i, j) and θ(i, j+1). In this case, θ(i, j) = −68°, θ(i, j+1)
= 12°, and the processing algorithm of the master station 19 explained in FIG. i's slave station No. j and
This means that it can be determined that deterioration has occurred in the interval j+1.

According to the master station algorithm of the above embodiment of the present invention, in S7 -160°≦θ(i,j)≦-6
If 0° is not established, the process immediately proceeds to S11 and the deteriorated section is output. However, on the other hand, the phase of all slave stations of the deteriorated feeder may be checked and then comprehensively determined. In this case, even if there is a problem with a slave station on the way, accurate judgment can be expected because it is looked at comprehensively. FIG. 10 shows a display screen of the display device that is the determination output result. Here, 34 is an I0 sensor, the arrow attached to each sensor is a deterioration direction determination result, and 101 is a symbol indicating a deterioration section. Moreover, FIG. 11 is a display screen of a display device that displays the absolute value of I0 obtained from each slave station and the phase information for V0 on a vector plane. On this plane, information indicating the degree of progress of deterioration obtained from the absolute value of I0 and phase information is also shown in different colors (not shown).

According to the above-described embodiment of the present invention, the influence of residual components and system noise can be reduced, so that the occurrence of insulation deterioration and its area can be detected with high sensitivity. In addition, a means for generating information that identifies degraded sections, such as arrows indicating the direction of deterioration occurrence, and at least part of the power distribution system diagram, and information indicating the degraded sections are displayed in the same screen area, allowing operators to easily identify degraded sections at a glance. You will be able to obtain information about. Furthermore, since the degree of progress of deterioration is shown in different colors, the operator can obtain deterioration information at a glance for taking the next countermeasure.

Sensor devices 10A to 10C of the above embodiment
, 11A to 11C, and 12A to 12C, only I0 is detected, but V0 may also be detected at the same time. A capacitor connected to a three-phase feeder is used as the V0 sensor. In this case, the point that the memory hold signal is transmitted from the slave station 21 is the same as in the above embodiment, but V0 and I0 are used to transmit the memory hold signal in the slave stations 13A to 13C, 14A to 14C, and 15A to 15C as shown in FIG. The difference is that the process described above includes processing up to direction determination. The master station 19 determines and outputs a degraded section using the direction determination result of the slave station. In the case of this embodiment, after the slave station 21 compares using V0, if it exceeds the reference value, it simply outputs a memory hold signal, and that V0 is used as data for determining the direction of deterioration. do not.

According to the above-described other embodiments of the present invention, it is possible to reduce the influence of residual components and system noise, to detect the occurrence of insulation deterioration and its area with high sensitivity, and to detect the direction determined by each slave station. Since only the determination result is transmitted, the amount of transmission can be reduced.

Another embodiment of the present invention will be explained based on the drawings. 12 and 13 are a plan view and a side view, respectively, of a ground fault generating device used for verification tests and algorithm phase setting of the present invention. The ground fault generating device includes a first electrode 120 connected to one phase of the distribution line, a second electrode 121 facing the first electrode 120 and connected to the ground potential, and the first electrode 120 connected to the ground potential. The manual arm 122 that is supported, the automatic arm 123 that supports the second electrode, the fixed frames 124 and 125 that respectively support the manual arm 122 and the automatic arm 123, and the fixed frames 124 and 125 are fixed. It is composed of a common base 128. The manual arm 122 and the fixed pedestal 124 are linked by a pinion gear (not shown) fixed to the manual arm 122 and a rack gear (not shown) fixed to the fixed pedestal 124, so that the manual arm 122 is connected to the axis of the electrode. It is configured so that it can be manually moved in two directions at right angles. On the other hand, the automatic arm 123 and the fixed frame 125 are linked by a pinion gear (not shown) fixed to the automatic arm 123 and a rack gear 126 fixed to the fixed frame 125, and the rack gear 126 is further rotated by the shaft of the stepping motor 127. The movable arm 123 is configured to be movable in the axial direction of the electrode. The rotation angle of the stepping motor 127 is configured to be controllable by a remote device (not shown). Incidentally, as the first and second electrode materials, an arc-resistant metal whose surface is not roughened by arc generation is used.

The operation will be explained. First, the position of the manual arm 122 is adjusted so that the axes of the second electrode 121 and the first electrode 120 coincide. Next, the number of pulses, that is, the rotation angle, to be output from the remote device to the stepping motor 127 is determined, and when the start button is pressed, the automatic arm 123 moves a predetermined distance to shorten the gap length between the electrodes. After generating this, the robot returns to its original position and completes the series of operations.

According to the above-described other embodiment of the present invention, it is possible to always control the gap length to a constant value, and since arc-resistant metal is used as the electrode material,
The reproducibility of ground fault waveforms is improved, making it possible to improve efficiency during verification tests and algorithm phase setting tests. Furthermore, in FIG. 3, it is also effective in improving the efficiency of the system resonance test performed to set the cutoff frequency of the low-pass filter 37 that removes system noise. In other words, by installing a ground fault generator in the system and generating a ground fault,
It is possible to constantly excite the free vibrations of the system stably,
Measurement of resonant frequency becomes easy.

[0063]

Effects of the Invention As explained above, according to the present invention, the effects of residual components and system noise in the zero-sequence voltage and zero-sequence current detected from the power system are reduced, thereby reducing insulation deterioration of the power system. This has the effect of allowing highly sensitive detection and determination of the occurrence and the period in which it occurs. Further, means for generating information for specifying a degraded section such as an arrow indicating the direction of occurrence of the degradation;
Since at least a portion of the power distribution system diagram and information indicating the section where deterioration has occurred are displayed in the same screen area, the operator can obtain information regarding deterioration at a glance.

Furthermore, since the gap length can always be controlled to a constant value and arc-resistant metal is used as the electrode material, it is possible to improve the efficiency of various tests.

[Brief explanation of the drawing]

FIG. 1 is a diagram in which an embodiment of the present invention is applied to a power distribution system.

FIG. 2 is a detailed diagram of the element device of the embodiment shown in FIG. 1;

FIG. 3 is a detailed view of another element device of the embodiment shown in FIG. 1;

FIG. 4 is a flow diagram showing a processing algorithm of the embodiment shown in FIG. 1;

FIG. 5 is an equivalent circuit diagram for explaining the operation of the present invention.

FIG. 6 is a vector diagram for explaining the operation of the present invention.

FIG. 7 is a functional explanatory diagram of the embodiment shown in FIG. 1;

8 is a diagram showing an example of data obtained in the example shown in FIG. 1. FIG.

9 is a diagram showing another example of data obtained in the example shown in FIG. 1. FIG.

FIG. 10 is an output result diagram obtained by the present invention.

FIG. 11 is another output result diagram obtained by the present invention.

FIG. 12 is a plan view of a test device obtained in another embodiment of the present invention.

FIG. 13 is a side view of a test device obtained in another embodiment of the present invention.

[Explanation of symbols]

7, 8, 9...Three-phase feeder (power transmission line), 10A to 10C
, 11A to 11C, 12A to 12C...sensor device, 13
A~13C, 14A~14C, 15A~15C...Slave stations,
16, 17, 18...Communication line, 19...Master station, 20...Sensor device, 21...Slave station.

Claims (27)

[Claims] Claim 1: In a device for detecting insulation deterioration in a three-phase power system, the occurrence of insulation deterioration occurs at the level of occurrence of zero-sequence voltage and/or zero-sequence current in a band other than the resonant frequency of the three-phase power system. An apparatus for detecting insulation deterioration in an electric power system, characterized in that detection is performed using the magnitude of . 2. A device for detecting insulation deterioration in a three-phase power system, wherein the insulation deterioration occurrence section is a phase difference spectrum between a zero-sequence voltage and a zero-sequence current in a band excluding the resonance frequency of the three-phase power system. A power system insulation deterioration detection device characterized in that the determination is made using the following. 3. In a device for detecting insulation deterioration in a three-phase power system, when a low frequency component of a zero-phase voltage is used as a trigger, occurrence of insulation deterioration occurs in a zero-phase in a band other than the resonant frequency of the three-phase power system. 1. An insulation deterioration detection device for a power system, characterized in that detection is performed using the magnitude of the generation level of voltage and/or zero-sequence current. 4. A device for detecting insulation deterioration in a three-phase power system, in which a low frequency component of a zero-phase voltage is used as a trigger, and an interval in which insulation deterioration occurs is a zero-phase in a band other than the resonant frequency of the three-phase power system. A power system insulation deterioration detection device characterized in that determination is made using a phase difference spectrum between voltage and zero-sequence current. 5. In claim 1 or 3, the zero-sequence voltage and/or zero-sequence current is a zero-sequence voltage in a band excluding the power supply frequency and the resonance frequency of the three-phase power system. , and/or a zero-sequence current. 6. In claim 1 or 3, the zero-sequence voltage and/or the zero-sequence current has a power frequency, a natural number multiple frequency thereof, and a resonance frequency of the three-phase power system. A power system insulation deterioration detection device characterized by detecting zero-sequence voltage and/or zero-sequence current in an exclusive band. 7. In claim 2 or 4, the zero-sequence voltage and zero-sequence current are the zero-sequence voltage and zero-sequence current in a band excluding the power supply frequency and the resonant frequency of the three-phase power system. A power system insulation deterioration detection device characterized by a phase current. 8. In claim 2 or 4, the zero-sequence voltage and zero-sequence current are in a band excluding the power supply frequency, its natural number multiples, and the resonance frequency of the three-phase power system. A power system insulation deterioration detection device characterized in that the zero-sequence voltage and zero-sequence current are as follows. 9. In a device for detecting insulation deterioration in a three-phase power system, the magnitude of the generation level of zero-sequence voltage and/or zero-sequence current in a band other than the power supply frequency is determined, and then A method for detecting insulation deterioration in a power system, characterized in that occurrence of insulation deterioration is detected using a low frequency component of a zero-sequence voltage in a frequency band as a trigger. 10. In claim 9, the zero-sequence voltage and/or zero-sequence current is a zero-sequence voltage and/or zero-sequence current in a band excluding the power supply frequency and its natural number multiple frequencies. A method for detecting insulation deterioration in a power system, characterized by: 11. A method for detecting insulation deterioration in a three-phase power system, wherein a phase difference spectrum of a zero-sequence voltage and a zero-sequence current in a band excluding the power supply frequency is determined, and then a phase difference spectrum of a zero-sequence voltage in a frequency band exceeding the power supply frequency is determined. A method for detecting insulation deterioration in a power system, characterized in that an insulation deterioration occurrence section is determined using a low frequency component of a phase voltage as a trigger. 12. Claim 11, characterized in that the zero-sequence voltage and zero-sequence current are zero-sequence voltage and zero-sequence current in a band excluding the power supply frequency and its natural number multiple frequencies. A method for detecting insulation deterioration in power systems. 13. The method for detecting insulation deterioration in an electric power system according to claim 9, wherein the low frequency component of the zero-sequence voltage is less than twice the frequency of the power supply. 14. In a device for determining insulation deterioration in a three-phase power system, the phase average value θ of zero-sequence current with respect to zero-sequence voltage in a band excluding the power supply frequency (however, |θ|≦180°) is - 90°+θ1>θ>−90°−θ2 (θ1, θ2
: constant ≦90°), it is determined that insulation deterioration has occurred on the load side, and -90°
+θ1<θ<180° or -90°−θ2>θ>
-180°, an insulation deterioration determination device for an electric power system is characterized in that it is determined that insulation deterioration has occurred on the power supply side. 15. In claim 14, the phase average value θ of the zero-sequence current with respect to the zero-sequence voltage is the phase of the zero-sequence current with respect to the zero-sequence voltage in a band excluding the power supply frequency and its natural number multiple frequencies. A power system insulation deterioration determination device characterized by an average value θ. 16. The apparatus for determining insulation deterioration in a power system according to claim 14 or 15, wherein θ1<θ2. 17. In any one of claims 14 to 16, the phase average value θ of the zero-sequence current is a phase average value in a low frequency region up to a natural number multiple frequency of the power supply frequency. This is an insulation deterioration determination device for electric power systems. 18. The insulation deterioration determination device for an electric power system according to claim 17, wherein the natural number multiple frequency of the power supply frequency is a frequency four times the power supply frequency. 19. An apparatus for determining insulation deterioration in an electric power system according to any one of claims 14 to 18, characterized in that the occurrence of insulation deterioration is determined from the power source side of the electric power system. 20. A device that causes a ground fault to such an extent that the circuit breaker of a distribution line connected via a circuit breaker does not operate, comprising: a first electrode connected to the distribution line; A ground fault generating device comprising: a second electrode facing the ground potential and connected to a ground potential; and means for controlling a gap length between the facing first electrode and the second electrode. 21. The ground fault generating device according to claim 20, wherein at least one of the first electrode and the second electrode includes an arc-resistant metal. 22. A resonant frequency measuring system for a power system, comprising the ground fault generating device according to claim 20 or 21, and means for measuring a resonant frequency specific to the power system. 23. Means for generating information specifying an insulation deteriorated section of a three-phase power system, and a display for displaying at least a part of the three-phase power system diagram and the information specifying the insulation deteriorated section in the same screen area. What is claimed is: 1. A power system insulation deterioration monitoring device comprising: 24. Means for calculating a phase average value θ and an absolute value of a zero-sequence current with respect to a zero-sequence voltage at at least one location in a three-phase power system; In the two-dimensional coordinate area showing the relationship with the value, information specifying the area where insulation deterioration occurs on the load side and/or the power supply side, and the phase average value θ of the zero-sequence current with respect to the zero-sequence voltage at the above-mentioned predetermined location. 1. A power system insulation deterioration monitoring device, comprising: a display device that simultaneously displays an absolute value and information corresponding to the absolute value. 25. In claim 24, the calculating means is means for calculating a phase average value θ and an absolute value of a zero-sequence current for each zero-sequence voltage at a plurality of locations, and the display device comprises: A power system insulation deterioration monitoring device, characterized in that it is a display device that displays information corresponding to a phase average value θ and an absolute value of a zero-sequence current with respect to a zero-sequence voltage at one of the plurality of locations. 26. In claim 24, the calculating means is means for calculating a phase average value θ and an absolute value of a zero-sequence current for each zero-sequence voltage at a plurality of locations, and the display device comprises: A power system insulation deterioration monitoring device characterized in that it is a display device that simultaneously displays information corresponding to a phase average value θ and an absolute value of a zero-sequence current with respect to a zero-sequence voltage at the plurality of locations. 27. Means for calculating the phase average value θ and absolute value of zero-sequence current with respect to zero-sequence voltage at at least one point in a three-phase power system; At the same time, information corresponding to the phase average value θ and absolute value of the zero-sequence current with respect to the zero-sequence voltage at the predetermined location is simultaneously displayed. 1. A power system insulation deterioration monitoring device, comprising: a display device for displaying information.