JP2017204973A - Phase interruption detection system, phase interruption detection apparatus and phase interruption detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve mechanical detection of a one-phase open-circuit failure causing no ground fault or short circuit regardless of an equipment configuration or a load state.SOLUTION: A phase interruption detection system includes a three-phase stationary induction type electrical apparatus, a current detector, an averaging part and a determination part. The three-phase stationary induction type electrical apparatus has a primary circuit in which an exciting current runs through a wiring of each phase. The current detector detects an exciting current of each phase of the primary circuit in the three-phase stationary induction type electrical apparatus. The averaging part samples an exciting current of each phase detected by the current detector at predetermined timing by a plurality of times and averages the exciting currents. The determination part determines whether or not the wiring of the primary circuit in a detection source of the exciting current is under an open state on the basis of the exciting current averaged by the averaging part.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an open phase detection system, an open phase detection device, and an open phase detection method.

  In a power generation facility such as a power plant, a protective relay is connected to a transformer that transforms a high voltage of three-phase alternating current, and measures are taken in the event of a landslide or short-circuit event.

  By the way, the insulator etc. connected to the primary side of the transformer is damaged and, for example, one of the three phases is lost (hereinafter referred to as “one-phase open failure”).

  A single-phase open fault in a three-phase transformer is difficult to find because a voltage is also induced in the open phase. For example, a single-phase open fault occurs on the primary side of the transformer, and the abnormal current value is a protective relay. Can be detected when the set value is reached.

  However, when a one-phase open failure that does not involve landslides or short circuits occurs, the value may not change to the set value of the protective relay depending on the equipment configuration and load conditions. In such a case, the single-phase open failure cannot be detected. Sometimes.

  For this reason, conventionally, in addition to mechanical detection, an attempt is made to detect a one-phase open failure without a ground or a short circuit by combining artificial detection.

JP, 2015-006076, A

  Conventionally, when a one-phase open failure that does not involve landslides or short circuits occurs, the value may not change up to the set value of the protective relay depending on the equipment configuration and load conditions. In this case, a single-phase open failure can be detected. First, it was handled by combining artificial detection.

  The problem to be solved by the present invention is that a phase-opening detection system, a phase-opening detection device, and a missing-phase detection device that can mechanically detect a one-phase open failure that does not involve a groundfall or a short circuit, regardless of the equipment configuration and load conditions. It is to provide a phase detection method.

  The phase loss detection system of the embodiment includes a three-phase static induction electrical device, a current detector, an averaging unit, and a determination unit. The three-phase static induction electric device has a primary side circuit in which an exciting current flows through the wiring for each phase. The current detector detects the excitation current of each phase of the primary side circuit of the three-phase static induction electrical device. The averaging unit samples a plurality of excitation currents for each phase detected by the current detector at a predetermined timing and averages them for each predetermined period. The determination unit determines whether or not the wiring of the primary side circuit from which the excitation current is detected is open based on the excitation current averaged by the averaging unit.

It is a figure which shows the structure of the phase loss detection system of embodiment. It is a figure which shows the signal containing a noise component (high frequency component). It is a figure which shows the signal which attenuate | damped the high frequency component with the analog filter. It is a figure which shows the signal which attenuate | damped the high frequency component with the digital filter. It is a figure for demonstrating sampling operation | movement. It is a figure which shows a very weak true electric current component. It is a figure which shows the 1st modification of a phase loss detection system. It is a figure which shows the 2nd modification of a phase loss detection system.

Hereinafter, embodiments will be described in detail with reference to the drawings.
FIG. 1 is a diagram functionally illustrating an open phase detection system according to one embodiment.

  As shown in FIG. 1, the phase loss detection system according to the first embodiment includes a transformer 1 as a three-phase static induction electrical device, and wirings 4 a, 4 b for each phase of a primary side circuit 2 of the transformer 1. A current detector 5 arranged in 4c, an instrument transformer PT (Potential Transformer) connected to one of the wirings 4a, 4b, 4c, and the current transformer 5 and current transformer 5 of each phase And an open phase detector 6 connected thereto.

  The transformer 1 includes a primary side circuit 2 including three-phase wirings 4a, 4b, 4c and a coil extending to the outside, and a secondary side circuit having a coil whose voltage is induced by the coil of the primary side circuit 2. 3. The coil of the primary side circuit 2 and the coil of the secondary side circuit 3 are magnetically coupled. Although not shown, the transformer 1 has an iron core that is a path for magnetic flux.

  In this transformer 1, an excitation current is caused to flow through the wires 4 a, 4 b, 4 c of the primary circuit 2, so that power corresponding to the winding ratio of the coils of the primary circuit 2 and the secondary circuit 3 is 2 Induced in the secondary circuit 3. The instrument transformer PT is a measuring device for obtaining a reference voltage Vref, and here detects an AC voltage applied to any wiring (for example, the wiring 44c) of the primary side circuit 2. And

  Since the voltage needs to be corrected when the reference voltage Vref detected by the instrument transformer PT is input to the phase loss detector 6, a voltage regulator 69 is provided. Further, since a noise component is included in the corrected voltage, the noise component is filtered from the voltage corrected by the voltage regulator 69 by providing an analog filter 63, an AD converter 64, a digital filter 65, and the like.

  The current detector 5 detects the current flowing through the wirings 4a, 4b, and 4c of each phase. For the current detector 5, for example, a Hall element type CT (CT having an iron core), an optical CT utilizing a Faraday effect, or the like is used. CT is an abbreviation for current transfer (current converter).

  Based on the excitation current detected by the current detector 5 of each phase, the phase loss detection device 6 determines whether or not the wiring 4a, 4b, 4c of the corresponding phase of the primary side circuit 2 from which the excitation current is detected is open. If there is an open wiring, an alarm is output to that effect.

  The phase loss detection device 6 includes an input converter 61, a filter unit 62, an averaging unit 66, a determination unit 67, and an alarm output unit 68.

  The input converter 61 converts the input excitation current (current signal) into a voltage signal. The filter unit 62 includes an analog filter 63, an AD converter 64, and a digital filter 65.

  The analog filter 63 attenuates a noise component (for example, a component obtained by converting a current of about 10 amperes into a voltage) included in a voltage signal obtained by converting the input excitation current.

  The AD converter 64 is an analog-digital converter that converts an excitation current (analog signal) whose noise component (high-frequency component) is attenuated by the analog filter 63 into a digital signal.

  The digital filter 65 filters a noise component (high frequency component) included in the digital signal converted by the AD converter 64. That is, the filter unit 62 is a band-pass filter that attenuates the high-frequency component of the voltage signal converted by the input converter 61. Thereby, a measurement error can be reduced.

  The averaging unit 66 samples a plurality of excitation currents for each phase detected by the current detector 5 at a predetermined timing and averages them for each predetermined period. More specifically, the averaging unit 66 samples a plurality of signals for each phase output from the filter unit 62 in synchronization with a predetermined timing, for example, one period of the frequency of the reference voltage Vref. By averaging the values every predetermined operation period (for example, 2 seconds), the noise component of the signal is reduced, and the true current component buried in the noise component is emphasized. For example, a current of about 0.2 A can be detected from noise of about 10 A.

  Based on the excitation current averaged by the averaging unit 66, the determination unit 67 determines whether or not the wiring of the primary side circuit from which the excitation current is detected is open.

  More specifically, the determination unit 67 determines whether the excitation current detection source primary side circuit 2 depends on whether or not a true current component appears for each excitation current component averaged by the averaging unit 66. It is determined whether or not the wirings 4a, 4b, and 4c are open (at least one phase is open failure). If the result of determination is that there is an open wiring (wiring 4b in this example), an alarm signal indicating that the wiring 4b is open is output to the alarm output unit 68.

  In other words, if the determination unit 67 averages the signal with the noise of about 10A and as a result it cannot detect a very weak current of about 0.2A, it determines that the wiring is in an open state and sends an alarm signal to the alarm output unit. Output to 68. As a result of averaging, if a very weak current of about 0.2 A can be detected, it is determined that the wiring is in a connected state (unopened state), and no alarm signal is output.

  The alarm output unit 68 is, for example, a speaker, a buzzer, or a display device, and is a notification unit that outputs an alarm that the wiring 4b is in an open state based on an alarm signal received from the determination unit 67. When there is a disconnection point P in the wiring 4b as in the example of FIG. 1, it is notified by an alarm sound or an alarm display that the wiring 4b is in an open state.

Hereinafter, the operation of the phase loss detection system of this embodiment will be described with reference to FIGS.
Normally, in a power generation facility, an excitation current is supplied to the primary side circuit 2 in a state where the secondary side circuit 3 is not loaded, and an operation check before operation is performed.

  In this case, when an exciting current is passed through the wirings 4 a, 4 b, 4 c of each phase of the primary side circuit 2, the exciting current is detected by each current detector 5 and input to the open phase detector 6.

  In the phase loss detection device 6, the input converter 61 converts the input excitation current (current signal) into a voltage signal including a noise component (high frequency component) 21 as shown in FIG. Output. Since a signal without phase loss includes a true current component 22 embedded in a noise component (high-frequency component) 21, the presence or absence of this phase can be determined by detecting the presence or absence of this signal. .

  In the filter unit 62, as shown in FIG. 3, the analog filter 63 generates a signal 23 in which the high frequency component of the analog voltage signal input from the input converter 61 is attenuated. Further, as shown in FIG. A signal 24 in which a high frequency component of the digital voltage signal is attenuated is generated and output to the averaging unit 66.

  The averaging unit 66 samples a plurality of signals 24 for each phase output from the filter unit 62 in accordance with the cycle of the reference voltage Vref, and averages them for each predetermined period (operation period). As the reference voltage Vref, an AC voltage applied to one of the wires (in this example, the wire 4c) of the primary circuit 2 or a normal commercial AC voltage (100 V, 50 Hz sine wave signal) is used.

  In this case, as shown in FIG. 5, if the operation period S to be averaged is 2 seconds, for example, when the frequency of the reference voltage Vref is 50 Hz, for example, the target signal is output 100 times from the cycle S1 to S100 of the reference voltage Vref. Sampling is performed, and an average value of the operation period S (S1 + S2 + S3 +... S99 + S100 / 100) is calculated.

  If the target signal contains completely random noise, the noise component is canceled by averaging and the error current is reduced to about 1/10. Ultimately, as shown in FIG. 6, a signal 25 (true current component) of only the excitation current in which the noise component is substantially converged is obtained.

  The determination unit 67 determines whether the wirings 4a, 4b, and 4c of the primary side circuit 2 that is the detection source of the excitation current depend on whether or not a true current component appears for each phase signal averaged by the averaging unit 66. It is determined whether or not one of them is in an open state.

  That is, when the true current component appears, the wiring of the corresponding primary circuit 2, in this example, the wirings 4 a and 4 c are not opened, and when the true current component does not appear, the corresponding primary side It can be determined that the wiring 4b of the circuit 2 is in an open state.

  If the result of this determination is that there is an open wiring (wiring 4b in this example), the determination unit 67 outputs an alarm signal indicating that there is an open wiring in the primary circuit 2 to the alarm output unit 68. To do. The alarm output unit 68 that has received the alarm signal from the determination unit 67 outputs an alarm.

  As described above, according to this embodiment, it is possible to measure a very small excitation current by reducing the noise component (measurement error) of the excitation current of each phase by the filter unit 62 and / or the averaging unit 66. It becomes. In other words, the influence of random noise, white noise and the like is reduced, and a minute excitation current of about 0.2 A, for example, can be detected.

  As a result, when the secondary circuit 3 of the transformer 1 is in a no-load state, detection of the opening of each wiring 4a, 4b, 4c of the primary circuit 2, that is, at least one of the three phases is detected. Is possible.

  That is, according to the present embodiment, it is possible to mechanically detect a one-phase open failure that does not involve a groundfall or a short circuit regardless of the equipment configuration and the load situation.

  Although the embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. 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 above embodiment, the phase loss detection device 6 includes the input converter 61, the filter unit 62, the averaging unit 66, the determination unit 67, and the alarm output unit 68. However, the alarm output unit 68 is an external element, and FIG. As shown in FIG. 4, the phase loss detection device 6 may include an input converter 61, an averaging unit 66, and a determination unit 67, for example.

  In this case, the averaging unit 66 samples a plurality of excitation currents for each phase detected by the current detector 5 at a predetermined timing and averages them for each predetermined period. The determination unit 67 averages the excitation currents averaged by the averaging unit 66. Based on the above, it is determined whether or not the wirings 4a, 4b, and 4c of the primary side circuit 2 from which the excitation current is detected are open.

  Moreover, as shown in FIG. 8, you may make it provide the input converter 61, the filter part 62, and the determination part 67. FIG. In this case, the filter unit 62 attenuates the high frequency component included in the excitation current of each phase detected by the current detector 5, and the determination unit 67 determines the excitation current based on the excitation current in which the high frequency component is attenuated by the filter unit 62. It is determined whether or not the wirings 4a, 4b, 4c of the primary side circuit 2 of the detection source are open.

  Furthermore, even in a no-load state, there are some impedance components in the circuit, so that a voltage is generated in each phase regardless of whether the wiring of the primary side circuit 2 is open or not open. Since the component whose phase is delayed by 90 ° with respect to this voltage is a current, attention is paid to the relationship between the phase of this current and the voltage.

  In this case, a voltage detector for detecting the voltage generated in each phase is provided, and based on the phase relationship between the voltage of each phase detected by this voltage detector and the excitation current of each phase detected by the current detector 5. It can be determined whether or not the wires 4a, 4b and 4c of the primary circuit 2 from which the excitation current is detected are open.

  In this case, the determination unit 67 confirms the presence or absence of a current having a 90 ° delay component with respect to the voltage for each phase detected by the voltage detection unit, whereby the wirings 4a and 4b of the primary side circuit 2 from which the excitation current is detected. Whether or not 4c is in an open state can be determined.

  That is, when a current of 90 ° delay component of the voltage generated in each phase is detected, the wiring of that phase is not in an open state, and when a current of 90 ° delay component is not detected (undetected), It can be determined that the wiring is in an open state. In this case, the phase loss detection device 6 includes an input converter 31, a voltage detection unit, and a determination unit 37.

  Furthermore, in the above-described embodiment, an example using a general iron core CT as a current detector has been described. However, a very small current of about 0.2 A, for example, that is not used for detecting a normal excitation current is detected. By arranging the light CT dedicated to the phase loss detection in each of the wirings 4a, 4b, and 4c, the noise component is saturated and cannot be detected, but only a weak excitation current can be detected.

  By setting the current detection unit to the optical CT, the cable to the phase loss detection device 6 can be made thin. Moreover, since detection in a low voltage region is possible according to the number of turns of the optical fiber, for example, when used as a gas insulated switchgear (GIS device), the weight can be reduced.

  Each component of the phase loss detection device 6 shown in the above embodiment may be realized by a program installed in a storage such as a hard disk device of a computer. The above program may be realized by a computer-readable electronic medium: electronic media. The function of the present invention may be realized by the computer by causing the computer to read the program from the electronic medium.

  Examples of the electronic medium include a recording medium such as a CD-ROM, flash memory, and removable media. Further, the configuration may be realized by distributing and storing components in different computers connected via a network, and communicating between computers in which the components are functioning.

  DESCRIPTION OF SYMBOLS 1 ... Transformer, 2 ... Primary side circuit, 3 ... Secondary side circuit, 4a, 4b, 4c ... Wiring, 5 ... Current detector, 6 ... Open-phase detector, 61 ... Input converter, 62 ... Filter part , 63 ... analog filter, 64 ... AD converter, 65 ... digital filter, 66 ... averaging section, 67 ... determination section, 68 ... alarm output section, 69 ... voltage regulator.

Claims (8)

A three-phase static induction electrical device having a primary circuit in which an excitation current is passed through the wiring for each phase;
A current detector for detecting an excitation current of each phase of the primary side circuit of the three-phase static induction electrical device;
An averaging unit that samples a plurality of excitation currents for each phase detected by the current detector at a predetermined timing and averages them for each predetermined period;
A phase loss detection system comprising: a determination unit that determines whether or not the wiring of the primary side circuit from which the excitation current is detected is open based on the excitation current averaged by the averaging unit. A three-phase static induction electrical device having a primary circuit in which an excitation current is passed through the wiring for each phase;
A current detector for detecting an excitation current flowing in the wiring of each phase of the primary circuit of the three-phase static induction electrical device;
A filter unit for attenuating high frequency components included in the excitation current of each phase detected by the current detector;
A phase loss detection system comprising: a determination unit that determines whether or not the wiring of the primary side circuit that is the detection source of the excitation current is in an open state based on the excitation current in which a high-frequency component is attenuated by the filter unit. A three-phase static induction electrical device having a primary circuit in which an excitation current is passed through the wiring for each phase;
A current detector for detecting an excitation current flowing in the wiring of each phase of the primary circuit of the three-phase static induction electrical device;
A voltage detector for detecting a voltage generated in each phase;
Based on the phase relationship between the voltage of each phase detected by the voltage detector and the excitation current of each phase detected by the current detector, the wiring of the primary circuit from which the excitation current is detected is opened. A phase failure detection system comprising: a determination unit that determines whether or not a state is present.   The phase loss detection system according to any one of claims 1 to 3, further comprising a notifying unit that notifies that when the wiring of the primary side circuit is in an open state as a result of the determination by the determining unit. . An averaging unit that samples a plurality of excitation currents for each phase detected by a current detector arranged in the wiring of each phase of the primary circuit of the three-phase static induction electrical device at a predetermined timing and averages the current every predetermined period; ,
A phase loss detection apparatus comprising: a determination unit that determines whether or not the wiring of the primary side circuit that is the detection source of the excitation current is in an open state based on the excitation current averaged by the averaging unit.   The phase loss detection apparatus according to claim 5, further comprising a notifying unit that notifies that when the wiring of the primary side circuit is in an open state as a result of the determination by the determining unit. The current detector detects the excitation current of each phase of the primary circuit of the three-phase static induction electrical equipment,
The averaging unit samples a plurality of detected excitation currents for each phase at a predetermined timing and averages it for each predetermined period.
A phase loss detection method in which the determination unit determines whether or not the wiring of the primary side circuit from which the excitation current is detected is in an open state based on the averaged excitation current.   The phase loss detection method according to claim 7, wherein as a result of the determination, when the wiring of the primary side circuit is in an open state, the fact is notified.

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