Detection device

Abstract

To contribute to detection of occurrence of dielectric breakdown on the basis of an AC signal in a low-voltage-side power system in a power transmission / distribution system for converting high voltage power into low voltage power.SOLUTION: A detecting device 100 includes a sensor section 101 that receives an AC signal from a power line in a secondary-side power system 20 that receives low voltage power obtained by converting high voltage power of a prescribed frequency in a primary-side power system 10 by a transformer 30, a filter section 102 that outputs one or a plurality of noise signals obtained by removing an at least frequency component of the prescribed frequency from the AC signal received by the sensor section 101, and a detecting section 103 that receives the one or plurality of noise signals and that when detecting a signal having an amplitude equal to or more than a first prescribed value in at least one noise signal out of the one or plurality of noise signals, outputs a detection signal representing occurrence of dielectric breakdown in the power line in the primary-side power system 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a detection device for detecting dielectric breakdown in an electric power transmission and distribution system. [Background technology]

[0002] Devices have been developed to detect insulation breakdown and corona discharges caused by insulation breakdown in power lines in power transmission and distribution systems. For example, there is a power line insulation condition detection device that includes a magnetic sensor that includes a magnetoresistive element and detects magnetic changes that occur when partial discharges, including corona discharges, occur in an insulated power line, and a filter that extracts a frequency band that includes characteristic frequency components caused by partial discharges from the output signal of the magnetic sensor (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-124629 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technology of Patent Document 1 (hereinafter referred to as the prior art), a sensor is brought close to insulation breakdown occurring in a high-voltage line to detect it, and therefore there is a problem with the ease of installation of the sensor.

[0005] An object of the present invention is to provide a detection device that contributes to detecting the occurrence of insulation breakdown based on an AC signal in a low-voltage power system in a power transmission and distribution system that converts high-voltage power to low-voltage power. [Means for solving the problem]

[0006] A detection device according to one aspect of the present invention comprises: a sensor unit that receives an AC signal from a power line in a secondary power system that receives low-voltage power obtained by voltage conversion of high-voltage power of a predetermined frequency in a primary power system by a power transformation device; a filter unit that outputs a noise signal by removing at least a frequency component of the predetermined frequency from the AC signal received by the sensor unit and extracts information on a plurality of phases whose absolute values ​​of positive and negative signal levels are maximum for each cycle of the AC signal; and a detection unit that receives the noise signal and, when detecting two signals in the noise signal that have amplitudes equal to or greater than a first predetermined value and are synchronized with two phases included in one cycle of the AC signal among the plurality of phases, outputs a detection signal indicating that a dielectric breakdown has occurred in the power line in the primary power system. Adopt the configuration. [Effects of the Invention]

[0007] According to the present invention, in a power transmission and distribution system that converts high-voltage power to low-voltage power, it is possible to contribute to making it possible to detect the occurrence of dielectric breakdown based on an AC signal in a power system on the low-voltage side. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing an example of the functional configuration of a power transmission and distribution system and a detection device according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a block diagram showing an example of the functional configuration of a filter unit according to a first embodiment of the present invention. [Figure 3] FIG. 10 is a block diagram showing another example of the functional configuration of the filter unit according to the first embodiment of the present invention. [Figure 4] A diagram used to explain the frequency characteristics of signal transmission in a substation [Figure 5] FIG. 1 is a flowchart showing an example of the operation flow of a detection unit according to the first embodiment of the present invention. [Figure 6] FIG. 10 is a block diagram showing another example of the functional configuration of the detection device and the filter unit according to the first embodiment of the present invention. [Figure 7] FIG. 10 is a flowchart showing another example of the operation flow of the detection unit according to the first embodiment of the present invention. [Figure 8] FIG. 1 is a diagram for explaining a method for detecting a dielectric breakdown signal included in a noise signal in a detection unit according to the first embodiment of the present invention. [Figure 9] FIG. 1 is a block diagram showing another example of the functional configuration of the power transmission and distribution system and the detection device according to the first embodiment of the present invention. [Figure 10] FIG. 1 is a block diagram showing an example of the functional configuration of a power transmission and distribution system and a detection device when three-phase AC power is input to a primary power system. [Figure 11] FIG. 10 is a block diagram showing another example of the functional configuration of a power transmission and distribution system and a detection device when three-phase AC power is input to a primary power system. [Figure 12]FIG. 1 is a block diagram showing an example of the functional configuration of a primary-side power system and a primary-side detection device included in a power transmission and distribution system according to a first modification. [Figure 13] FIG. 10 is a block diagram showing another example of the configuration of the primary-side power system and the primary-side detection device according to the first modification. [Figure 14] FIG. 1 is a block diagram showing an example of a functional configuration of a primary-side detection device according to a first modification; [Figure 15] FIG. 10 is a block diagram showing another example of the functional configuration of the primary-side detection device according to the first modification. [Figure 16] FIG. 1 is a block diagram showing an example of a specific functional configuration of a primary-side power system and a primary-side detection device according to a first modification. [Figure 17] FIG. 1 is a block diagram showing another example of a specific functional configuration of a primary-side power system and a primary-side detection device according to Modification 1. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Background of the Invention of One Aspect of the Present Invention)

[0010] First, as a technical background, in recent years, the number of devices that use electricity as an energy source has increased, placing an increasing burden on power transmission and distribution facilities that support the demand for electricity. Furthermore, as the use of devices connected to computers that perform calculations constantly or intermittently increases, even a momentary instability in the supply of electricity has a significant impact on the global economy, and therefore there is a demand for the provision of high-quality power transmission and distribution networks.

[0011] Power transmission and distribution facilities are designed to transmit and distribute electricity at high voltages from the perspective of energy efficiency, and the power lines through which AC power is transmitted are coated with insulating materials. However, insulating materials deteriorate over time, and as their insulating properties deteriorate, breakdown can occur. Furthermore, in coastal power transmission and distribution facilities, partial breakdown can occur due to the effects of salt in seawater. When such breakdown occurs, the properties of the insulating material deteriorate at an accelerated rate. Therefore, in order to stably provide the high-quality power transmission and distribution network described above, it is important to detect breakdown before it occurs or at an early stage.

[0012] Generally, dielectric breakdown occurs on the high-voltage side of a power transmission and distribution system where a high voltage is applied, and when dielectric breakdown occurs, a partial short circuit in the power line occurs as an initial symptom. Therefore, in order to detect dielectric breakdown early, a technology that can capture the phenomenon caused by a partial short circuit is required, and such a technology has been developed for some time, as in the conventional technology described above.

[0013] However, as described above, in the conventional technology, since a sensor is brought into contact with or close to a breakdown occurring in a high-voltage line to detect the breakdown, there are problems with the ease of installation of the sensor or the detection of the breakdown phenomenon. Specifically, for example, in the conventional technology, in order to install a conventional sensor on a high-voltage power line, it is necessary to temporarily suspend the power transmission and distribution network to ensure the safety of the installation, and the installation work requires a high level of specialized technical skill.

[0014] Therefore, the inventors of the present invention conceived of a detection device that detects insulation breakdown by applying a sensor and a filter to the low-voltage side, rather than the high-voltage side, which is more difficult to work on, in a power transmission and distribution system that includes a high-voltage primary power system, a substation, and a low-voltage secondary power system, and came to invent one aspect of the present invention.

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments, components having the same functions are assigned the same reference numerals, and duplicated descriptions will be omitted. The embodiment described below shows one specific example of the present disclosure. The configurations shown in the embodiments, the processes or processing orders in the flow charts, etc. are merely examples and do not limit the technology of the present disclosure.

[0016] (Embodiment 1) The configurations of a power transmission and distribution system 1 and a detection device 100 according to this embodiment will be described with reference to FIG.

[0017] 1 is a block diagram showing an example of the functional configuration of a power transmission and distribution system and a detection device according to a first embodiment of the present invention. In FIG. 1, the power transmission and distribution system 1 includes a primary power system 10, a secondary power system 20, a substation 30, and a detection device 100.

[0018] 1, the primary side power system 10 is a power system to which high voltage power is connected, and may be connected to high voltage power with a voltage of, for example, 6000 V. An AC signal of high voltage power is propagated through the power lines of the primary side power system 10, and the predetermined frequency of the AC signal of high voltage power may be the frequency of commercially distributed power. The predetermined frequency may be, for example, 50 Hz or 60 Hz.

[0019] 1, secondary power system 20 is a power system to which low-voltage power is connected, and may be connected to low-voltage power having a voltage of, for example, 100 V. An AC signal of low-voltage power is propagated through the power lines of secondary power system 20, and the predetermined frequency of the AC signal of low-voltage power may be, for example, 50 Hz or 60 Hz, similar to the AC signal of high-voltage power.

[0020] In FIG. 1, the primary power system 10 and the secondary power system 20 are each illustrated as being a single system for ease of explanation, but this is not limited thereto. The primary power system 10 and the secondary power system 20 may each be a single system, or the power lines may be a three-phase, three-wire system, as described below. The number of systems in each power system does not limit the scope of the present disclosure. The single system illustrated in FIG. 1 may be one phase in a three-phase, three-wire system.

[0021] The high-voltage power may be referred to as a first-voltage power, and the low-voltage power may be referred to as a second-voltage power having a voltage lower than the first-voltage power.

[0022] 1, the power transformer 30 may be a device that has a function of converting high-voltage power in the primary power system 10 into low-voltage power in the secondary power system 20. As shown in Fig. 1, the power transformer 30 may have a structure including a transformer, for example. The transformer has a structure in which multiple coils are wound around a magnetic body, and at least one pair of the coils are inductively coupled.

[0023] The power transformation function of the power transformation device 30 uses this inductance coupling to convert high voltage power in the primary power system 10 into low voltage power in the secondary power system 20. Note that the power transformation function of the power transformation device 30 and specific structural examples of the power transformation device 30 are well known, and therefore detailed description thereof will be omitted.

[0024] 1, detection device 100 has a sensor unit 101, a filter unit 102, and a detection unit 103. In this embodiment, detection device 100 for detecting insulation breakdown in the power lines of primary-side power system 10 is connected to the power lines of secondary-side power system 20 to ensure the safety of the detection operation. Specifically, for example, sensor unit 101 is connected to the power lines of secondary-side power system 20.

[0025] The sensor unit 101 may have a function of receiving an AC signal from a power line in the secondary power system 20, for example. The sensor unit 101 may be, for example, a capacitive sensor having a sensor element. Specifically, for example, the capacitive sensor may be a sensor formed by connecting a sensor element to a power line in the secondary power system 20 via an insulating material. In such a case, a capacitive coupling is formed between the power line and the sensor element according to the dielectric constant of the insulating material, and the capacitive sensor may receive an AC signal transmitted through the power line based on the capacitive coupling.

[0026] As will be described later, the AC signal received by the sensor unit 101 may include a noise signal in addition to a frequency component of a predetermined frequency of the power transmission / distribution target. As will be described later, the noise signal may include at least one of a dielectric breakdown signal generated when dielectric breakdown occurs in the primary power system 10 and a noise signal generated by electrical equipment connected to the secondary power system 20. Details will be described later.

[0027] The dielectric breakdown signal is a signal that is generated when dielectric breakdown occurs in the power line of the primary power system 10. Dielectric breakdown is a phenomenon that occurs when the absolute value of the instantaneous voltage of the power line is large, and is accompanied by a highly impulsive current.

[0028] The insulating material may include at least one of an insulating coating provided on the sensor element and an insulating coating on the power line. When an insulating coating on the power line is used, the surface of the sensor element is made conductive, thereby maintaining adhesion with the power line and enabling good signal acquisition. On the other hand, when an insulating coating on the sensor element is used, the sensor element can be attached to a conductive power line. The insulating coating may be made of an insulating material such as resin or ceramic. In the present disclosure, the power line may be referred to as a distribution line or a transmission line.

[0029] 1, the filter unit 102 outputs one or more noise signals obtained by removing at least a frequency component of a predetermined frequency from the AC signal received by the sensor unit 101. That is, the filter unit 102 may receive an AC signal propagating through a power line of the secondary-side power system 20, and output noise signals obtained by removing at least a 50 Hz or 60 Hz signal, which is a frequency component of the AC power signal, from the AC signal. By removing the 50 Hz band or the like, which is a power frequency, in this way, it is possible to easily detect a breakdown signal propagated from the primary-side power system 10 to the secondary-side power system 20, as will be described later.

[0030] One or more noise signals may be output from the filter unit 102. When multiple noise signals are output, the filter unit 102 may have a signal distribution function, distribute the AC signal into multiple signals using the signal distribution function, and remove a frequency component of a predetermined frequency from each of the distributed signals.

[0031] In FIG. 1, the detection unit 103 may receive a noise signal output from the filter unit 102, and when detecting a dielectric breakdown signal in the noise signal, output a detection signal indicating that dielectric breakdown has occurred in a power line in the primary power system.

[0032] Specifically, for example, when the detection unit 103 detects a signal having an amplitude equal to or greater than a first predetermined value in a noise signal obtained by removing at least the frequency component of the power frequency from an AC signal, the detection unit 103 may determine that the detected signal is a breakdown signal that has been generated by a breakdown in the primary-side power system 10 and has propagated to the secondary-side power system 20 via the transformer 30. The specific numerical value of the first predetermined value is threshold information for distinguishing between a breakdown signal and other noise signals, and may be uniquely determined by measurements or experiments performed in advance.

[0033] That is, the detection unit 103 may receive one or more noise signals, and when it detects a signal having an amplitude equal to or greater than a first predetermined value in at least one of the one or more noise signals, it may output a detection signal indicating that a breakdown has occurred in a power line in the primary power system.

[0034] The detection unit 103 may be a control circuitry that controls each unit by an electric signal. Specifically, the detection unit 103 may be configured by an integrated circuit such as an FPGA (Field Programmable Gate Array). The detection unit 103 may also be realized by a CPU (Central Processing Unit) or an MPU (Micro Processing Unit).

[0035] As described above, the detection device 100 in this embodiment may include a sensor unit 101 that receives an AC signal from a power line in the secondary power system 20, which receives low-voltage power obtained by voltage conversion of high-voltage power of a predetermined frequency in the primary power system 10 by the substation 30; a filter unit 102 that outputs one or more noise signals obtained by removing frequency components of at least a predetermined frequency from the AC signal received by the sensor unit 101; and a detection unit 103 that receives the one or more noise signals and, when detecting a signal having an amplitude equal to or greater than a first predetermined value in at least one of the one or more noise signals, outputs a detection signal indicating that insulation breakdown has occurred in the power line in the primary power system 10.

[0036] This can contribute to making it possible to detect the occurrence of dielectric breakdown based on AC signals in a low-voltage power system in a power transmission and distribution system that converts high-voltage power into low-voltage power.

[0037] Specifically, for example, by attaching a sensor 101 to the power line of the secondary power system 20 on the low-voltage side and detecting the occurrence of dielectric breakdown based on the AC signal received from the sensor 101, the ease of installation and safety of the detection device that detects dielectric breakdown can be significantly improved.

[0038] The functional configuration and basic operation of the detection device 100 according to this embodiment have been described above with reference to FIG.

[0039] Fig. 2 is a block diagram showing an example of the functional configuration of a filter unit according to the first embodiment of the present invention. As shown in Fig. 2, the filter unit 102a may include a first filter 201a. The first filter 201a may receive an AC signal and output a first noise signal obtained by removing at least frequency components of a predetermined frequency from the AC signal based on the frequency pass characteristics of the first filter, which removes frequency components of 50 Hz or 60 Hz, which are the power frequencies of AC power, as shown in Fig. 2.

[0040] In this case, the frequency pass characteristics of the first filter may be such that, as shown in Fig. 2, the frequency pass characteristics of the first filter further remove equipment noise frequencies of noise signals generated by electrical equipment connected to the secondary power system 20. The electrical equipment may be, for example, an inverter or other device that uses commercial power.

[0041] The detection device 100 in this embodiment is used in the secondary power system 20 of the power transmission and distribution system 1, and therefore can ensure safety of work etc. compared to conventional techniques, but may cause problems specific to the secondary power system 20. The specific problems include, for example, noise signals emitted by electrical equipment connected to the secondary power system 20.

[0042] In contrast, the filter unit 102a in this embodiment may remove frequency components of a predetermined frequency and also frequency components of equipment noise from the AC signal received from the sensor unit 101. The frequency components of equipment noise generated from electrical equipment may be identified by measuring them in advance. Furthermore, since the frequency band of equipment noise may be several hundred times or more higher than the power frequency of 50 Hz or the like, the first filter 201a may be a band-pass filter, thereby removing frequency components of a predetermined frequency and also frequency components of equipment noise from the AC signal.

[0043] That is, the secondary power system 20 transmits power to one or more electrical equipment, the filter unit 102 includes a first filter 201a that removes frequency components of a predetermined frequency and frequency components of noise signals based on the electrical equipment, and the one or more noise signals may include at least a first noise signal extracted from the AC signal by the first filter 201a.

[0044] This allows the detection unit 103 to detect with high accuracy the dielectric breakdown signal superimposed on the noise signal output from the filter unit 102.

[0045] As will be described later, breakdown occurring in the power lines of the primary-side power system 10 has impulse characteristics, and therefore, the breakdown signal propagated along the power lines due to breakdown is a signal having frequency components over a very wide band. Therefore, from the perspective of detecting breakdown signals, it is desirable that the first filter 201a be a high-pass filter having frequency characteristics that remove only frequency components of the power frequency and pass frequencies higher than the power frequency. However, as described above, when detecting breakdown signals on the secondary-side power system 20 side, which is unique to this embodiment, it is necessary to remove noise signals from electrical equipment connected to the secondary-side power system 20. Therefore, it is desirable that the first filter 201a have the function of removing some of the wide-band frequency components of the breakdown signal.

[0046] On the other hand, the frequency pass characteristic of the first filter may be, for example, one that passes a frequency band corresponding to the frequency characteristic of the inductive coupling in the transformer 30, as shown in FIG.

[0047] The inductive coupling of the transformer in the substation 30 has frequency characteristics that are set to have bandpass characteristics that minimize pass loss in the 50 Hz or 60 Hz power frequency band. Therefore, by making the frequency pass characteristics of the first filter 201a correspond to the frequency characteristics of the inductive coupling in the transformer while removing frequency components of the power frequency, it is possible to remove frequency components of a predetermined frequency and, further, frequency components of equipment noise that are higher in frequency than the predetermined frequency, from the AC signal received by the sensor unit 101.

[0048] That is, the filter unit 102 includes a first filter 201a that passes a frequency band that is higher than a predetermined frequency and corresponds to the frequency characteristics of the inductance coupling in the substation 30, and the one or more noise signals may include at least a first noise signal extracted from the AC signal by the first filter 201a.

[0049] This allows the detection unit 103 to detect with high accuracy the dielectric breakdown signal superimposed on the noise signal output from the filter unit 102. Other effects are as described above.

[0050] Fig. 3 is a block diagram showing another example of the functional configuration of the filter unit according to the first embodiment of the present invention. Although Fig. 2 illustrates that the filter unit 102a may include only the first filter 201a, as shown in Fig. 3, the filter unit 102b may include the first filter 201b and the second filter 202b.

[0051] 3, first filter 201b may have a first frequency characteristic that removes frequency components of the power frequency and passes a first frequency band 301 that is lower than a second frequency band that second filter 202b passes, and may output a first noise signal based on the first frequency characteristic. Second filter 202b may have a second frequency characteristic that removes frequency components of the power frequency and passes a second frequency band 302 that is higher than the first frequency band, and may output a second noise signal based on the second frequency characteristic.

[0052] That is, the one or more noise signals may include a first noise signal extracted from the AC signal by a first filter 201b that passes a first frequency band 301, and a second noise signal extracted from the AC signal by a second filter 202b that passes a second frequency band 302 that is a frequency band higher than the first frequency band 301.

[0053] The detector 103b may output a detection signal in at least one of the following cases: when the detector 103b detects a first noise signal having an amplitude equal to or greater than a first predetermined value, and when the detector 103b detects a second noise signal having an amplitude equal to or greater than a second predetermined value. In such a case, the first predetermined value and the second predetermined value may be substantially the same value or may be different values.

[0054] In this way, filter unit 102b has first filter 201b that passes the first frequency band and second filter 202b that passes the second frequency band that is higher than the first frequency band, so that frequency components of a breakdown signal having impulse characteristics can be captured over a wide frequency band, as will be described later, and detection unit 103 can detect the breakdown signal with higher accuracy. Note that first frequency band 301 and second frequency band 302 are preferably divided into a lower frequency band and a higher frequency band, respectively, than a boundary frequency as shown in Fig. 3, for example. The boundary frequency may be, for example, about several hundred kHz.

[0055] The first filter 201b may be a low-pass filter or a band-pass filter, and the second filter 202b may be a high-pass filter or a band-pass filter. The first filter 201b may be a low-pass filter to remove frequency components higher than the first frequency band 301, but a band-pass filter that removes frequency components of the power frequency is more preferable to facilitate detection processing of the dielectric breakdown signal in the detection unit 103b. The second filter 202b may be a high-pass filter to remove frequency components lower than the second frequency band 302, or a band-pass filter that removes unnecessary frequency components higher than the second frequency band 302.

[0056] In this case, it is desirable that the first frequency band 301 is adapted to the frequency components of the inductive coupling in the transformer 30, and the second frequency band 302 is adapted to the frequency components of the capacitive coupling in the transformer 30.

[0057] Fig. 4 is a diagram used to explain the frequency characteristics of signal transmission in the substation 30. Below, with reference to Fig. 4, the frequency transmission characteristics of AC signals in the substation 30 will be explained, and the effect of adapting the first frequency band 301 and the second frequency band 302 to the frequency components of inductive coupling and capacitive coupling in the substation 30, respectively, will be explained.

[0058] The inductive coupling of the transformer in the substation 30 has frequency characteristics that are set to minimize insertion loss in the power frequency band. Specifically, for example, the frequency characteristics of the inductive coupling may have band-pass characteristics as shown in Fig. 4(a), with insertion loss being minimized in the 50 Hz or 60 Hz power frequency band, and insertion loss increasing as the frequency moves away from the power frequency.

[0059] On the other hand, the transformer in the substation 30 has a structure in which multiple coils are wound, and therefore capacitive coupling occurs between the coils and between the transformer housings, etc. As shown in Fig. 4(b), this capacitive coupling has a characteristic in which the impedance decreases as the frequency increases, and therefore, of the signals propagating through the power lines of the primary-side power system 10, high-frequency components propagate to the secondary-side power system 20 by capacitive coupling rather than by inductance coupling.

[0060] Therefore, the signal transmission in the substation 30 has frequency characteristics that propagate the power frequency as a whole, as shown in Figure 4(c), but also has frequency characteristics that propagate a certain level of signal even in frequency bands higher than the power frequency.

[0061] In this way, the substation 30 is designed to efficiently transform AC power from the primary power system 10 to the secondary power system 20 mainly through inductance coupling, but capacitive coupling also exists between the primary power system 10 and the secondary power system 20, and the substation 30 has the characteristic of transmitting high-frequency signals even in the high-frequency range.

[0062] Therefore, when a breakdown signal having impulse characteristics is propagated from the primary-side power system 10 to the secondary-side power system 20 via the transformer 30, frequency components in the inductive coupling frequency band and the capacitive coupling frequency band among the wideband frequency components based on the impulse characteristics of the breakdown signal are propagated with less loss. That is, by adapting the first frequency characteristic of the first filter 201b and the second frequency characteristic of the second filter 202b to the inductive coupling frequency band and the capacitive coupling frequency band, respectively, the detection unit 103b can detect the breakdown signal with higher accuracy.

[0063] In this case, in the signal detection determination process in the detector 103b shown in FIG. 3, the second predetermined value may be substantially the same as the first predetermined value.

[0064] Alternatively, the second predetermined value may be smaller than the first predetermined value. By making the second predetermined value, which is a threshold for determining whether or not a breakdown signal is present in the second noise signal, smaller than the first predetermined value, which is a threshold for the first noise signal, a design can be achieved that takes into account the pass characteristics of capacitive coupling, which have higher loss than the pass characteristics of inductive coupling as shown in Fig. 4. Because the pass characteristics change depending on the electrical characteristics and frequency characteristics of the coupling, it is desirable to set the first predetermined value and the second predetermined value according to the magnitude of loss given by the pass characteristics.

[0065] Furthermore, by using the first filter 201b and the second filter 202b, it is possible to remove components of frequency bands other than the pass frequency band of the second filter 202b from noise signals that may be generated in the high frequency range and are caused by electrical equipment, and it is also possible to solve the problem of noise signals that are caused by electrical equipment in the secondary power system 20, which is unique to this embodiment.

[0066] The frequency band of the capacitive coupling is based on the connection topology of the primary-side power system 10 and the secondary-side power system 20 and the configuration of the transformer 30, and therefore may be determined in advance by measurement, experiment, or the like, and the second filter 202b may be designed based on the information on the frequency band of the capacitive coupling. The frequency band of the capacitive coupling may also be designed to cover a plurality of frequency characteristics of capacitive coupling corresponding to a plurality of transformers 30 with different specific configurations. Similarly, the values ​​of the first predetermined value and the second predetermined value may also be set based on the frequency characteristics of inductive coupling and capacitive coupling determined in advance by design, measurement, experiment, or the like.

[0067] In such a case, when the detection unit 103b cannot detect a signal having an amplitude equal to or greater than the first predetermined value in the first noise signal, the detection unit 103b may determine whether or not a signal having an amplitude equal to or greater than the first predetermined value is present in the second noise signal.

[0068] 5 is a flowchart showing an example of the flow of operation of the detection unit according to the first embodiment of the present invention. Hereinafter, an example of the procedure of processing the basic operation of the detection unit 103b will be described with reference to FIG.

[0069] Note that the flow charts described below merely illustrate steps necessary to explain the operational processing procedures of the detection device 100 according to the present disclosure. This does not preclude steps related to the processing of other operations from being appropriately inserted between the steps of each flow chart, as long as the functionality of the embodiment of the present invention is achieved. The above explanations regarding the flow charts may also be applied to the flow charts described below.

[0070] 5, the detection unit 103b receives a first noise signal and a second noise signal (step S501). Next, the detection unit 103b may determine whether or not the first noise signal contains a signal having an amplitude equal to or greater than the first predetermined value (step S502). When the detection unit 103b detects the signal (step S502: YES), the detection unit 103b may output a detection signal indicating that a breakdown has occurred in the power line of the primary-side power system 10 (step S503).

[0071] On the other hand, when the detecting unit 103b cannot detect a signal having an amplitude equal to or greater than the first predetermined value in the first noise signal (step S502: NO), it may determine whether or not a signal having an amplitude equal to or greater than the second predetermined value is present in the second noise signal (step S504). Then, when the detecting unit 103b detects a signal having an amplitude equal to or greater than the second predetermined value in the second noise signal (step S504: YES), it may output a detection signal. On the other hand, when the detecting unit 103b cannot detect a signal having an amplitude equal to or greater than the second predetermined value in the second noise signal (step S504: NO), it may enter a standby state.

[0072] In this way, in the detection unit 103b, by prioritizing the detection and determination process of the insulation breakdown signal in the first noise signal over the detection and determination of the insulation breakdown signal in the second noise signal, it is possible to preferentially detect the frequency component of the insulation breakdown signal that propagates to the secondary power system 20 due to the inductance coupling with low transmission loss in the substation 30, which has the effect of increasing the degree of freedom in setting the first predetermined value and the second predetermined value.

[0073] 5, the detection and determination process for the dielectric breakdown signal in the first noise signal is given priority over the detection and determination of the dielectric breakdown signal in the second noise signal, but this is not limited to this. The detection unit 103 may execute the detection and determination process for the first noise signal and the detection and determination process for the second noise signal in parallel, and output a detection signal when a dielectric breakdown signal is detected in either one or both. Furthermore, the detection unit 103 may give priority to the detection and determination process for the dielectric breakdown signal in the second noise signal over the detection and determination of the dielectric breakdown signal in the first noise signal.

[0074] 3 and 5, the filter unit 102b has been described as including the first filter 201b and the second filter 202b, but may further include an extraction unit. Fig. 6 is a block diagram showing another example of the functional configuration of the detection device and the filter unit according to the first embodiment of the present invention.

[0075] 6, the filter unit 102c has a first filter 201b and a second filter 202b, and may further have an extraction unit 600. That is, the filter unit 102c may further have an extraction function of extracting, based on the AC signal received by the sensor unit 101, phase information including at least information on at least one first phase in which the absolute value of the signal level of the AC signal is maximum.

[0076] Specifically, the extraction unit 600 may have a phase information extraction function, and the phase information extraction process may be performed by an information processing operation. The extraction unit 600 may have a function of extracting phase information of a frequency component of a power frequency contained in an AC signal. The extracted phase information may include at least information about the phase at which the absolute value of the signal level of the AC signal is maximum. Note that, since techniques for extracting one or more pieces of phase information from an AC signal are well known, detailed description thereof will be omitted.

[0077] The information on the first phase, at which the absolute value of the signal level of the AC signal is maximum, is used when the downstream detection unit 103c detects and determines whether a breakdown signal is included in the noise signal. This is because breakdown that can occur in the power lines of the primary-side power system 10 occurs at the timing when the absolute value of the signal level of the AC signal is maximum, and therefore, by using the information on the first phase corresponding to this timing, the downstream detection unit 103c can determine with high accuracy whether the signal included in the noise signal is a breakdown signal.

[0078] The phase information may include one or more pieces of information about the first phase. When the downstream detecting unit 103c detects and determines whether or not a breakdown signal has occurred, high accuracy can be achieved by using one piece of information about the first phase, but even higher accuracy can be achieved by using multiple pieces of information about the first phase.

[0079] Note that a phase difference occurs between the power signal propagating in the power line of the primary power system 10 and the power signal propagating in the power line of the secondary power system 20 due to the presence of the substation 30. However, this phase difference is fixed at a constant value depending on the connection configuration of the power systems or the characteristics of the transformer in the substation. Therefore, when determining the presence or absence of an insulation breakdown signal contained in a noise signal based on phase information, the phase information of the AC signal in the secondary power system 20 can be used as a reference.

[0080] In such a case, when the detector 103c in FIG. 6 detects a signal in the second noise signal that has an amplitude equal to or greater than a third predetermined value and that is not synchronized with the first phase, the detector 103c may output a detection signal based on the detection of a signal in the first noise signal that has an amplitude equal to or greater than a first predetermined value.

[0081] Fig. 7 is a flow chart showing another example of the flow of operation of the detection unit according to the first embodiment of the present invention. Fig. 8 is a diagram used to explain a method for detecting a breakdown signal included in a noise signal in the detection unit according to the first embodiment of the present invention. An example of the basic operation process of the detection unit 103c will be described below with reference to Figs. 7 and 8. Note that in the description of Fig. 7, explanations of steps that overlap with Fig. 5 will be omitted.

[0082] In FIG. 7, when the detection unit 103c receives the first noise signal and the second noise signal (step S501), it determines whether or not the second noise signal output from the second filter 202b contains a signal having an amplitude equal to or greater than a third predetermined value that is not synchronized with the first phase (step S701).

[0083] The second noise signal is a signal having frequency components in a higher frequency band than the first noise signal, and therefore, when the noise signal includes a dielectric breakdown signal, the second noise signal includes frequency components in the higher frequency band of the dielectric breakdown signal having impulse characteristics.

[0084] When a breakdown occurs in the power line of the primary-side power system 10, a breakdown signal 801 is detected in the first noise signal in synchronization with the first phase 800 as shown in Fig. 8(b), while a breakdown signal 802 is detected in the second noise signal in synchronization with the first phase 800 as shown in Fig. 8(c). Because the frequency of breakdown signal 801 is lower and its wavelength is longer than that of breakdown signal 802, the number of waves detected in synchronization with the first phase 800 is relatively small. Therefore, there are more opportunities to detect a breakdown signal synchronized with the first phase 800 based on the second noise signal.

[0085] On the other hand, in the secondary-side power system 20, a noise signal 803 caused by electrical equipment may be included in the AC signal, and the noise signal occurs randomly without being synchronized with the first phase 800 of the AC signal, and as described above, is more likely to be superimposed on the second noise signal than on the first noise signal. Therefore, if the amplitude level of the noise signal 803 caused by electrical equipment included in the second noise signal is equal to or greater than a third predetermined value, it may be difficult to determine the presence or absence of a breakdown signal based on the second noise signal, regardless of the frequency of detection of a breakdown signal synchronized with the first phase 800.

[0086] Therefore, in step S701, the detection unit 103c determines whether or not there is a noise signal 803 caused by electrical equipment having an amplitude of a third predetermined value or more that is not synchronized with the first phase in the second noise signal output from the second filter 202b, and when a noise signal 803 having an amplitude of the third predetermined value or more is detected (step S701: YES), the detection unit 103c outputs a detection signal based on the detection of a signal having an amplitude of the first predetermined value or more in the first noise signal (step S702).

[0087] Specifically, for example, when the detection unit 103c detects a signal having an amplitude equal to or greater than a first predetermined value in the first noise signal (step S702: YES), it may output a detection signal (step S503), and when it does not detect the signal (step S702: NO), it may enter a standby state.

[0088] On the other hand, when the detection unit 103c does not detect a noise signal 803 caused by electrical equipment having an amplitude equal to or greater than a third predetermined value that is not synchronized with the first phase 800 in the second noise signal (step S701: NO), the detection unit 103c may output a detection signal based on the second noise signal in which a dielectric breakdown signal can be detected relatively frequently (step S703).

[0089] In this way, depending on whether or not noise signal 803 is detected in the second noise signal, it is determined which of the detection and determination processes for the dielectric breakdown signal in the first noise signal and the detection and determination process for the dielectric breakdown signal in the second noise signal should be given priority. This makes it possible to ensure both an opportunity to detect a signal synchronized with first phase 800 and a degree of freedom in setting the first and second predetermined values.

[0090] 7, the detector 103c may output a detection signal when it detects a signal in the first noise signal that has an amplitude equal to or greater than a first predetermined value and is synchronized with the first phase. This allows the dielectric breakdown signal to be detected in the first noise signal with higher accuracy.

[0091] 6, the filter unit 102 has been described as including a plurality of filters, but the filter unit 102 may instead be configured to include one filter and the extraction unit 600. That is, the filter unit 102 may further include an extraction function for extracting, based on the AC signal received by the sensor unit 101, phase information including at least information about at least one first phase in which the absolute value of the signal level of the AC signal is maximized, and the detection unit 103 may output a detection signal when it detects, in at least one noise signal among the one or more noise signals, a signal that has an amplitude equal to or greater than a first predetermined value and is further synchronized with the first phase.

[0092] This makes it possible to determine with high accuracy the presence or absence of a breakdown signal based on phase information, without separating the noise signal obtained by removing the power frequency component from the AC signal by frequency.

[0093] In the above description, the sensor unit 101 receives an AC signal from one power line in the secondary power system 20. However, for example, as shown in Fig. 9, the sensor unit 101d may receive AC signals from multiple power lines in the secondary power system 20. In such a case, the sensor unit 101d and the filter unit 102d may have two systems of the functions and configurations included in the sensor unit 101 and the filter unit 102 described above.

[0094] That is, the sensor unit 101d may receive a first AC signal from a first power line including a first endpoint 901 in the secondary power system 20, and may receive a second AC signal from a second power line including a second endpoint in the secondary power system 20; the filter unit 102d may output a third noise signal obtained by removing at least a frequency component of a predetermined frequency from the first AC signal received by the sensor unit 101d, and may output a fourth noise signal obtained by removing at least a frequency component of a predetermined frequency from the second AC signal; and the detection unit 103d may receive the third noise signal and the fourth noise signal, and output a detection signal based on the third noise signal and the fourth noise signal.

[0095] In FIG. 9, for example, the AC power extracted as commercial power between the first terminal point 901 and the second terminal point 902 may be 200 V, and since the midpoint between the first terminal point 901 and the second terminal point 902 is grounded, 100 V may be extracted between each terminal point and the ground point.

[0096] In this case, when a breakdown signal occurs due to breakdown in primary power system 10, the breakdown signal propagates to secondary power system 20, and propagates through a first power line including first terminal point 901 and a second power line including second terminal point 902. Meanwhile, secondary power system 20 is divided into systems at the midpoint described above, and each system has an independent load, so that load noise signals are also generated independently.

[0097] That is, while the breakdown signal generated in the primary power system 10 propagates to the first power line and the second power line, the load noise signals propagating in each power line of the secondary power system 20 are independent of each other. Therefore, by, for example, adding a third noise signal obtained by removing at least a predetermined frequency component from the first AC signal received from the first power line and a fourth noise signal obtained by removing at least a predetermined frequency component from the second AC signal received from the second power line, when breakdown occurs, the amplitude level of the breakdown signal increases, while the load noise signals contained in the third noise signal and the fourth noise signal are canceled out.

[0098] Therefore, the detection unit 103d can detect dielectric breakdown with higher accuracy by outputting a detection signal when it detects a signal in the added noise signal that has an amplitude equal to or greater than a fourth predetermined value that is greater than the first predetermined value described above.

[0099] Furthermore, the detection unit 103d may output the detection signal when detecting a signal having an amplitude equal to or greater than a first predetermined value in at least one of a third noise signal obtained by removing at least a frequency component of a predetermined frequency from a first AC signal received from a first power line and a fourth noise signal obtained by removing at least a frequency component of a predetermined frequency from a second AC signal received from a second power line.

[0100] Furthermore, the detection unit 103d may output a detection signal based on the result of performing other known arithmetic processing other than addition using a third noise signal obtained by removing at least a frequency component of a predetermined frequency from the first AC signal received from the first power line, and a fourth noise signal obtained by removing at least a frequency component of a predetermined frequency from the second AC signal received from the second power line.

[0101] That is, the detection unit 103d may receive the third noise signal and the fourth noise signal, and output the detection signal based on the third noise signal and the fourth noise signal.

[0102] In this way, by adding the AC power received from the first power line including the first end point and the second power line including the second end point in the secondary power system 20 and then detecting and determining the breakdown signal, the load noise signal is canceled out, making it possible to detect breakdown with high accuracy.

[0103] In the above description, the primary power system 10 and the secondary power system 20 are each described as including a single power system, but for example, when three-phase AC power is input to at least the primary power system 10, the sensor unit 101 may receive AC signals from power lines in multiple phases.

[0104] Fig. 10 is a block diagram showing an example of the functional configuration of the power transmission and distribution system and the detection device when three-phase AC power is input to the primary power system 10. Hereinafter, with reference to Fig. 10, the functional configuration and operation of the power transmission and distribution system 1 and the detection device 100 when three-phase AC power is input to the primary power system 10 will be described. Note that, for ease of explanation, a diagram of the configuration of the primary power system 10 is omitted in Fig. 10.

[0105] As shown in FIG. 10 , the high-voltage power in the primary-side power system 10 may be high-voltage three-phase AC power, and the high-voltage three-phase AC power may be input to a transformer 30, from which low-voltage AC power may be output as the secondary-side power system 20. In such a case, the three phases in the primary-side power system 10 may be, for example, R-phase, S-phase, and T-phase. Meanwhile, in the secondary-side power system 20, the low-voltage power in the secondary-side power system 20 may be two-phase AC power or low-voltage three-phase AC power. As shown in FIG. 10 , if the AC power is two-phase, it may be, for example, U-phase and V-phase. Note that if the AC power is three-phase, it may be U-phase, V-phase, and W-phase.

[0106] As shown in FIG. 10 , for example, the U phase in the secondary power system 20 may be inductively coupled to the R phase and the S phase of the three phases in the primary power system 10 by the transformer 30, and the V phase in the secondary power system 20 may be inductively coupled to the S phase and the T phase in the primary power system 10.

[0107] The three phases in the primary-side power system 10 may be referred to as a primary-side first phase, a primary-side second phase, and a primary-side third phase, and the two phases in the secondary-side power system 20 may be referred to as a secondary-side first phase and a secondary-side second phase. The first, second, and third phases on the primary side may correspond to any of the R, S, and T phases, respectively, and the first and second phases on the secondary side may correspond to any of the U and V phases, respectively. The connection topology between the primary-side power system 10 and the secondary-side power system 20 does not limit the scope of the present disclosure.

[0108] In this case, the sensor unit 101e included in the detection device 100e may receive, for example, AC signals from two-phase power lines in the secondary power system 20. That is, the sensor unit 101e may receive, in the secondary power system 20, a first-phase AC signal in a power line of a secondary-side first phase in the secondary power system 20 that is inductively coupled to a primary-side first phase and a primary-side second phase of the three phases in the primary power system 10 by the transformer 30, and a second-phase AC signal in a power line of a secondary-side second phase that is inductively coupled to a primary-side second phase and a primary-side third phase.

[0109] Specifically, for example, as shown in Fig. 10, the sensor unit 101e may receive AC signals from both the U-phase power line and the V-phase power line. Note that the selection of two phases in Fig. 10 is an example, and the sensor 101e may receive AC signals from both the V-phase power line and the W-phase power line.

[0110] In such a case, the filter unit 102e may output at least one or more first-phase noise signals obtained by removing at least a frequency component of a predetermined frequency from the first-phase AC signal, and one or more second-phase noise signals obtained by removing at least a frequency component of a predetermined frequency from the second-phase AC signal.

[0111] The filter unit 102e may output a first phase noise signal and a second phase noise signal by removing at least a frequency component of a predetermined frequency from each of the first phase AC signal and the second phase AC signal, for example, by applying the first filter 201a to each of the first phase AC signal and the second phase AC signal, as described in FIG. 2.

[0112] When the power lines in the primary power system 10 are three-phase, three-wire systems, if a breakdown occurs in any of the three phases of the primary power system 10, a breakdown signal is propagated to all phases in the secondary power system 20.

[0113] Specifically, when a breakdown occurs in the R phase, for example, the breakdown signal propagates from the R phase to the U and W phases due to inductive coupling in the substation 30. Meanwhile, as described above, the breakdown signal has impulse characteristics, and therefore high-frequency components of the frequency components of the breakdown signal propagate to, for example, the U and V phases due to capacitive coupling in the substation 30 and the primary and secondary power systems 10 and 20. The same explanation applies when breakdown occurs on a power line connected to the S or T phase, rather than the R phase. Specifically, capacitive coupling in the substation 30 may include, for example, capacitive coupling caused by the arrangement or wiring of multiple conductors and conductive housings in the substation 30.

[0114] Therefore, if a breakdown occurs in any phase of the primary side power system 10, a breakdown signal having an amplitude equal to or greater than the first predetermined value is detected in both the first phase noise signal and the second phase noise signal obtained by removing frequency components of a predetermined frequency from each AC signal in the filter unit 102e.

[0115] Therefore, when the downstream detection unit 103e detects a signal having an amplitude equal to or greater than a first predetermined value in at least one of the first-phase noise signal and the two-phase noise signal, it may output a detection signal indicating that a dielectric breakdown has occurred in the power line in the primary-side power system 10.

[0116] On the other hand, as described above, since electrical equipment is connected to the secondary power system 20, noise signals originating from the electrical equipment are superimposed on the AC signals propagating through the power lines in the secondary power system 20.

[0117] For this reason, as described above, it is desirable to eliminate noise signals, and for example, the first filter 201a included in the filter unit 102e may further eliminate equipment noise frequencies of noise signals generated by electrical equipment connected to the secondary power system 20, as described in Fig. 2. That is, the secondary power system 20 transmits power to one or more pieces of electrical equipment, the filter unit 102 includes one or more first filters that eliminate frequency components of predetermined frequencies and frequency components of noise signals based on the electrical equipment, and the one or more first-phase noise signals may include at least noise signals extracted from the first-phase AC signals by the first filters, and the one or more second-phase noise signals may include at least noise signals extracted from the second-phase AC signals by the first filters.

[0118] Furthermore, first filter 201a may be a filter that passes a frequency band that is higher than a predetermined frequency and that corresponds to the frequency characteristics of inductive coupling in power transformation device 30. That is, filter unit 102 may include one or more first filters that pass a frequency band that is higher than a predetermined frequency and that corresponds to the frequency characteristics of inductive coupling in power transformation device 30, and one or more first phase noise signals may include at least a noise signal extracted from the first phase AC signal by the first filter, and one or more second phase noise signals may include at least a noise signal extracted from the second phase AC signal by the first filter.

[0119] In this case, when breakdown occurs in primary-side power system 10, the breakdown signals included in the first-phase noise signal and the second-phase noise signal input to detection unit 103e are both frequency components of the insulation signal propagated from primary-side power system 10 by inductance coupling in transformer 30. Therefore, for example, when breakdown occurs in the primary-side first phase, the breakdown signal is detected in the first-phase noise signal, but the breakdown signal is not detected in the second-phase noise signal.

[0120] In this case, the detector 103e may output a detection signal when a breakdown signal having a first predetermined amplitude is detected in at least one of the first phase noise signal and the second phase noise signal. Furthermore, the detection signal may be, for example, a signal further indicating that breakdown has occurred in the primary-side first-phase power line.

[0121] The filter unit 102e may output one or more first-phase noise signals and one or more second-phase noise signals. When multiple noise signals are output, the filter unit 102e may have a signal distribution function, divide each AC signal into multiple signals using the signal distribution function, and remove a frequency component of a predetermined frequency from each of the divided signals.

[0122] That is, the detection unit 103e may receive the first phase noise signal and the second phase noise signal, and output a detection signal when detecting a signal having an amplitude equal to or greater than a first predetermined value in at least one of the first phase noise signal and the second phase noise signal.

[0123] In this way, in a power transmission and distribution system in which the power lines in the primary power system 10 are three-phase, three-wire, when an AC signal is received from the two-layer power lines in the secondary power system 20 and at least the frequency components of the power frequency are removed from the AC signal, it is possible to detect at least that insulation breakdown has occurred in the primary power system 10.

[0124] Furthermore, in the filter unit 102e, the frequency components of the power frequency and the frequency components propagated by capacitive coupling are removed from the AC signal, thereby making it possible to identify the phase in which the breakdown has occurred among the three phases of the primary side power system 10.

[0125] The detector 103e may add the first-phase noise signal and the second-phase noise signal together, and output a detection signal when a signal having an amplitude equal to or greater than a fifth predetermined value is detected in the added signal. By adding the first-phase AC signal and the second-phase AC signal in the secondary power system 20 together in this manner and then detecting or determining whether or not a breakdown signal has occurred, the load noise signal is canceled out, as described above, and breakdown can be detected with high accuracy.

[0126] In the above description, an AC signal is received from a two-phase power line in the secondary power system 20, and a first filter is applied to the AC signal to detect the occurrence of a breakdown. However, as shown in Fig. 11, an AC signal may be received from a three-phase power line in the secondary power system 20, and the breakdown signal may be detected based on the three AC signals. This increases the chances of detecting a breakdown signal in the secondary power system 20, and makes it possible to detect the occurrence of a breakdown with higher accuracy.

[0127] As shown in FIG. 11, the various noise signals propagating through the U-phase, V-phase, and W-phase power lines in secondary power system 20 have mutually independent phase information. Therefore, by detecting the breakdown signal based on the three AC signals received from each of the three-phase power lines, it is possible to detect the occurrence of breakdown with high accuracy.

[0128] In the above description, the sensor unit 101 may be a capacitive sensor, but is not limited to a capacitive sensor as long as it can at least receive AC signals transmitted through power lines. For example, the sensor 101 may be attached to the power lines while maintaining electrical conductivity. In such a case, since no insulating material is present, the AC signals received by the sensor 101 contain minute signals, which has the effect of enabling more accurate detection of dielectric breakdown signals.

[0129] In the above description, the sensor 101 receives an AC signal from the power line of the secondary power system 20, and the frequency component of the power frequency is removed from the AC signal received by the sensor 101. However, for example, the presence or absence of a breakdown signal may be determined by using information on the first phase extracted from the AC signal using an extraction unit, without removing the frequency component of the power frequency from the AC signal.

[0130] That is, the detection device 100 may include a sensor unit 101 that receives an AC signal from a power line in the secondary power system 20, which receives low-voltage power obtained by voltage conversion of high-voltage power of a predetermined frequency in the primary power system 10 by a substation 30; a filter unit 102 that extracts, based on the AC signal received by the sensor unit 101, phase information including at least information about at least one first phase in which the absolute value of the signal level of the AC signal is maximum; and a detection unit 103 that, when detecting a signal in the AC signal that has an amplitude equal to or greater than a first predetermined value and is further synchronized with the first phase, outputs a detection signal indicating that insulation breakdown has occurred in the power line in the primary power system 10.

[0131] The present invention is not limited to the above-described embodiment, and various modifications are possible. Each of the modifications will be described below.

[0132] (Variation 1) In the description of the first embodiment, it has been described that the occurrence of a breakdown in the power lines in the primary-side power system 10 is detected based only on the AC signal received by the sensor unit 101 from the power lines in the secondary-side power system 20. However, for example, in the case where the high-voltage power in the primary-side power system 10 is high-voltage three-phase AC power as shown in FIGS. 10 and 11 , whether or not a breakdown signal has occurred may be detected based on the AC signal propagating through the power lines in the secondary-side power system 20 and, further, on a third AC signal corresponding to the vector sum of the AC signals in the power lines of each of the three phases of the primary-side power system 10.

[0133] That is, in the first embodiment, the detection device 100 is described as being connected to the power lines of the secondary power system 20 to ensure the safety of the work of detecting insulation breakdown, but the vector sum of the AC signals in each of the three-phase power lines of the primary power system 10 is zero and a balanced state is maintained when no abnormality such as insulation breakdown, earth fault, or leakage current occurs. Therefore, the work of detecting insulation breakdown based on this vector sum is safer than when a sensor is brought into contact with or close to insulation breakdown occurring in a high-voltage line to detect it.

[0134] In this first variant, when a breakdown occurs in a power line in at least one of the three phases, the discharge phenomenon caused by the breakdown disrupts the above-mentioned equilibrium state, and since the breakdown occurs when the absolute value of the AC signal is at its maximum, the breakdowns in the three phases do not cancel each other out. In light of this, the breakdown may be detected by detecting a signal indicating the disruption of the above-mentioned equilibrium state.

[0135] Fig. 12 is a block diagram showing an example of the functional configuration of the primary-side power system 10 and the primary-side detection device included in the power transmission and distribution system in Modification 1. Fig. 13 is a block diagram showing another example of the configuration of the primary-side power system 10 and the primary-side detection device in Modification 1.

[0136] The functional configuration and operation of the primary-side power system 10 and the primary-side detection device 1200 according to Modification 1 will be described below with reference to Figures 12 and 13. For ease of explanation, configuration diagrams of the secondary-side power system 20 and the inductance of the transformer 30 corresponding to the secondary-side power system 20 are omitted in Figures 12 and 13.

[0137] 12, the high-voltage power in the primary power system 10 is high-voltage three-phase AC power, and the high-voltage three-phase AC power is input to the transformer 30, and the three phases in the primary power system 10 may be, for example, R phase, S phase, and T phase. In such a case, the wiring configuration of the inductance in the transformer 30 may be star type, V type, or delta type, and the wiring configuration of the inductance does not limit the scope of the present disclosure.

[0138] In FIG. 12 , the primary-side detecting device 1200 may receive a third AC signal corresponding to the vector sum of AC signals on the three-phase power lines of the primary power system 10. The third AC signal may be an AC signal corresponding to the vector sum of AC signals on the three-phase power lines of the primary power system 10. For example, the third AC signal may be a vector sum of signals propagated from the three-phase power lines of the primary power system 10 by capacitive coupling or inductive coupling. For example, the third AC signal may be an AC signal received by capacitive coupling as the vector sum of AC signals propagated on the three-phase power lines of the primary power system 10. For example, as will be described in detail later, the third AC signal may be an AC signal induced based on the vector sum of AC signals on the three-phase power lines. That is, the third AC signal may be a signal indicating amplitude information and phase information of the vector sum of AC signals on the three-phase power lines. The third AC signal may be referred to as a zero-phase signal. The zero-phase signal may be a zero-phase current or a zero-phase voltage.

[0139] The third AC signal, which corresponds to the vector sum of the AC signals in each of the three-phase power lines, is zero and maintains a balanced state when no abnormalities, such as breakdown or leakage current, occur in any of the three-phase power lines. On the other hand, if an abnormality, such as breakdown or leakage current, occurs in at least one of the three-phase power lines, the third AC signal will have a value. As described above, a breakdown signal can occur when the absolute value of the amplitude of the AC signal propagating through each phase's power line is maximized. Therefore, even if breakdown occurs in all three phases, the multiple breakdown signals appearing in the third AC signal will not cancel each other out. Therefore, it is possible to detect breakdown in three-phase power lines based on the third AC signal.

[0140] 13, when the inductance in the power transformer 30 is connected in a star configuration, the primary-side detector 1200 may receive the third AC signal based on a signal propagating on a ground line connecting the neutral point and the ground. The signal propagating on the ground line is a vector sum of the AC signals propagating on the respective power lines of the three phases, and may be referred to as a primary-side noise signal in the present disclosure.

[0141] 13 , the primary-side noise signal includes, for example, a noise signal generated in the primary-side power system 10, and if a breakdown occurs in a power line in the primary-side power system 10, an impulse signal generated due to the breakdown may be superimposed on the primary-side noise signal. The primary-side detection device 1200 may receive a third AC signal based on the primary-side noise signal, for example, via capacitive coupling. The primary-side detection device 1200 may detect the impulse signal included in the third AC signal. Note that the neutral grounding method shown in FIG. 13 is an example, and the neutral grounding method does not limit the scope of the present disclosure.

[0142] Fig. 14 is a block diagram showing an example of the functional configuration of a primary-side detecting device in Modification 1. As shown in Fig. 14, a primary-side detecting device 1200a may have a primary-side sensor unit 1201 and a primary-side detection unit 1202. For example, as shown in Fig. 13, the primary-side sensor unit 1201 may be connected to a ground line and have a function of receiving the third AC signal by capacitive coupling or inductive coupling. The primary-side sensor unit 1201 may be, for example, a capacitive sensor having a sensor element.

[0143] Specifically, for example, the capacitive sensor may be a sensor formed by connecting a sensor element to a ground line via an insulating material. In such a case, a capacitive coupling is formed between the ground line and the sensor element according to the dielectric constant of the insulating material, and the capacitive sensor may receive a third AC signal via the capacitive coupling based on the primary-side noise signal. As described above, the third AC signal received by the primary-side sensor unit 1201 may include a dielectric breakdown signal when dielectric breakdown occurs in the primary-side power system 10.

[0144] The insulating material may include at least one of an insulating coating provided on the sensor element and an insulating coating on the ground wire. When an insulating coating on the ground wire is used, the surface of the sensor element is made conductive, thereby maintaining adhesion with the ground wire and enabling good signal acquisition. On the other hand, when an insulating coating on the sensor element is used, the sensor element can be attached to a conductive ground wire. The insulating coating may be made of an insulating material such as resin or ceramic.

[0145] 14 , primary-side detection unit 1202 may receive the third AC signal from primary-side sensor unit 1201, and when detecting a breakdown signal in the third AC signal, output a primary-side detection signal indicating that breakdown has occurred in a power line in the primary-side power system. Specifically, for example, when primary-side detection unit 1202 detects a signal in the third AC signal that has an amplitude equal to or greater than a preset sixth predetermined value and that occurs periodically at predetermined phase intervals, primary-side detection unit 1202 may determine that the detected signal is a breakdown signal caused by breakdown in a power line in primary-side power system 10.

[0146] The specific numerical value of the sixth predetermined value is threshold information for distinguishing between a breakdown signal and other noise signals, and may be uniquely determined by measurements or experiments carried out in advance.

[0147] Furthermore, since breakdown is a phenomenon that occurs when the absolute value of the instantaneous voltage in the power lines of the primary power system is large and is accompanied by a highly impulsive current, for example, if breakdown occurs in one of the three phases, breakdown signals will occur periodically at 180-degree phase intervals. If breakdown signals occur in two of the three phases, breakdown signals will occur periodically at 60-degree and 120-degree phase intervals. If breakdown signals occur in all three phases, breakdown signals will occur periodically at 60-degree phase intervals.

[0148] In this way, since the breakdown signal occurs periodically at a predetermined phase interval, the primary side detection unit 1202 may determine that breakdown has occurred when it detects a signal that has an amplitude equal to or greater than a sixth predetermined value and that occurs periodically at a predetermined phase interval. Note that since methods for detecting signals that occur periodically at a predetermined phase interval are well known, detailed explanations thereof will be omitted.

[0149] The primary side detection unit 1202 may be a control circuitry that controls each unit using an electrical signal. Specifically, the primary side detection unit 1202 may be configured with an integrated circuit such as an FPGA (Field Programmable Gate Array). The primary side detection unit 1202 may also be realized by a CPU (Central Processing Unit) or an MPU (Micro Processing Unit).

[0150] The primary-side detection signal output from the primary-side detection unit 1202 may be received by the detection unit 103. For example, the detection unit 103 may receive the primary-side detection signal from the primary-side detection device 1200 and output a detection signal when detecting a signal having an amplitude equal to or greater than a first predetermined value in at least one of the first-phase noise signal and the second-phase noise signal.

[0151] That is, when the primary-side detector 1200 detects a breakdown signal and at least one of the first-phase noise signal and the second-phase noise signal has an amplitude equal to or greater than a first predetermined value, the detector 103 may determine that breakdown has occurred in the primary-side power system 10. Note that detailed description of configurations and functions that overlap with the description of Figures 10 and 11 will be omitted.

[0152] In this way, the detection device 100 according to the present first modification further includes a primary-side detection device 1200 that receives a third AC signal corresponding to the vector sum of the AC signals in the power lines of each of the three phases in the primary power system 10, and outputs a primary-side detection signal indicating that a breakdown has occurred in the power lines in the primary power system 10 when it detects a signal in the third AC signal that has an amplitude greater than or equal to a sixth predetermined value and that occurs periodically at predetermined phase intervals. The detection unit 103 may receive the primary-side detection signal from the primary-side detection device 1200, and output the detection signal when it detects a signal in at least one of the first-phase noise signal and the second-phase noise signal that has an amplitude greater than or equal to a first predetermined value.

[0153] This can contribute to enabling highly accurate detection of the occurrence of dielectric breakdown based on AC signals in a low-voltage power system in a power transmission and distribution system that converts high-voltage power to low-voltage power.

[0154] Note that primary-side detecting device 1200 may further include a primary-side filter unit 1203, as shown in Fig. 15. Fig. 15 is a block diagram showing another example of the functional configuration of the primary-side detecting device in Modification 1. Primary-side filter unit 1203 may remove frequency components of noise signals emitted by electrical equipment connected to secondary-side power system 20, which may be propagated to primary-side power system 10 based on capacitive coupling occurring between coils in substation 30 and between transformer housings and the like.

[0155] That is, in such a case, the secondary power system 20 transmits power to one or more electrical equipment, the primary side detection device 1200 further has a primary side filter unit 1203, which removes frequency components of noise signals based on the electrical equipment, and the primary side detection unit 1202 may output a primary side detection signal indicating that insulation breakdown has occurred in a power line in the primary side power system 10 when it detects, from the third AC signal, a signal from which the frequency components of the noise signals based on the electrical equipment have been removed, the signal having an amplitude equal to or greater than a sixth predetermined value and occurring periodically at predetermined phase intervals.

[0156] This allows the primary-side detector 1200 to detect the dielectric breakdown signal superimposed on the third AC signal with high accuracy.

[0157] In the above description, the inductance is connected in a star configuration as shown in FIG. 13, but this is not limiting, and the scope of the present disclosure is not limited to this configuration.

[0158] Fig. 16 is a block diagram showing an example of a specific functional configuration of the primary-side power system and the primary-side detection device in Modification 1. For example, as shown in Fig. 16, the third AC signal may be a vector sum of signals propagated on conductors connecting shields 1600 that cover the power lines of the three phases. As described above, based on the third AC signal, a breakdown that has occurred in at least one of the three phases may be detected.

[0159] As described above, the third AC signal may be an AC signal induced based on the vector sum of the AC signals in the three-phase power lines. Fig. 17 is a block diagram showing another example of a specific functional configuration of the primary-side power system and the primary-side detection device in Modification 1.

[0160] As shown in FIG. 17 , each of the three-phase power lines may pass through a current sensor 1700, and the primary-side detection device 1200 may receive the current induced in the current sensor 1700 as a third AC signal. The current sensor 1700 may be, for example, a current transformer including a magnetic core, an iron core, a coil, and the like. If the vector sum of the AC signals in each of the three-phase power lines is not zero due to dielectric breakdown or the like, an induced current is generated in the current sensor 1700, and the primary-side detection device 1200 may receive this current as a third AC signal. The current sensor 1700 may be, for example, a zero-phase current transformer (ZCT) for detecting ground leakage. In this case, adding the current sensor 1700 to an existing sensor enables partial discharge detection, thereby facilitating installation in existing substation facilities. A detailed description of the current sensor 1700 is omitted here because it is a known technique. The specific configuration of the current sensor 1700 does not limit the scope of the present disclosure.

[0161] 16 and 17, for ease of explanation, configuration diagrams of the secondary-side power system 20 and configuration diagrams of the inductances in the transformer 30 corresponding to the secondary-side power system 20 are omitted. In addition, the wiring configuration of the inductances in the transformer 30 shown in Fig. 16 and 17 is an example, and the connection configuration between the primary-side power system 10 and the secondary-side power system 20 does not limit the scope of the present disclosure.

[0162] In the above description of the present modified example 1, it has been described that whether or not a breakdown signal has occurred is detected based on the AC signal propagating through the power lines in the secondary power system 20 and the third AC signal in the primary power system 10. However, for example, whether or not a breakdown signal has occurred may be detected based only on the third AC signal in the primary power system 10.

[0163] That is, the present invention may be a primary-side detection device in a substation system in which high-voltage three-phase AC power of a predetermined frequency in a primary power system is voltage-converted by a substation, the detection device including: a primary-side sensor unit that receives a third AC signal corresponding to the vector sum of the AC signals in the power lines of each of the three phases in the primary power system; and a primary-side detection unit that outputs a primary-side detection signal indicating that insulation breakdown has occurred in the power lines in the primary power system when it detects a signal in the primary-side noise signal that has an amplitude equal to or greater than a sixth predetermined value and that occurs periodically at predetermined phase intervals.

[0164] This allows the primary-side detector 1200 to easily detect the dielectric breakdown signal superimposed on the primary-side noise signal.

[0165] In the above description, a description of known techniques relating to each function is omitted. For example, in the AC power circuit of the present disclosure, circuit elements and the like may be inserted as appropriate.

[0166] In the above explanation, "including at least one of A, B, and C" may mean that it may be a combination of one or two or more of A, B, and C. [Industrial Applicability]

[0167] The detection device according to the present invention is effective in general for detecting insulation breakdown in power transmission and distribution systems. [Explanation of symbols]

[0168] 1. Power transmission and distribution system 10 Primary power system 20 Secondary power system 30 Substation equipment 100 Detection device 101 Sensor section 102 Filter section 103 Detection unit 600 Extraction part 1200 Primary side detector 1201 Primary side sensor part 1202 Primary side detection unit 1203 Primary filter section 1600 Shield 1700 Current Sensor

Claims

1. a sensor unit that receives an AC signal from a power line in a secondary power system that receives low-voltage power obtained by voltage conversion of high-voltage power of a predetermined frequency in a primary power system by a transformer; a filter unit that outputs a noise signal obtained by removing at least the frequency component of the predetermined frequency from the AC signal received by the sensor unit, and extracts information on a plurality of phases at which absolute values ​​of positive and negative signal levels are maximized for each cycle of the AC signal; a detection unit that receives the noise signal, and when detecting two signals in the noise signal that have amplitudes equal to or greater than a first predetermined value and that are synchronized with two phases included in one cycle of the AC signal among the plurality of phases, outputs a detection signal that indicates that a breakdown has occurred in a power line in the primary side power system; A detection device comprising:

2. the secondary power system transmits power to one or more electrical equipment; the filter unit includes a filter that removes frequency components of the predetermined frequency and frequency components of noise signals due to the electrical equipment. The detection device of claim 1 .

3. the filter unit includes a filter that passes a frequency band that is higher than the predetermined frequency and corresponds to the frequency characteristics of inductance coupling in the power transformer. The detection device of claim 1 .

4. the high-voltage power is high-voltage three-phase AC power, the sensor unit receives, in the secondary-side power system, a first-phase AC signal in a power line of a secondary-side first phase in the secondary-side power system that is inductively coupled to a primary-side first phase and a primary-side second phase of the three phases in the primary-side power system by the transformer, and a second-phase AC signal in a power line of a secondary-side second phase that is inductively coupled to the primary-side second phase and the primary-side third phase; the filter unit outputs at least one or more first-phase noise signals obtained by removing at least the frequency component of the predetermined frequency from the first-phase AC signal, and one or more second-phase noise signals obtained by removing at least the frequency component of the predetermined frequency from the second-phase AC signal, the detection unit receives the first phase noise signal and the second phase noise signal, and outputs the detection signal when detecting the two signals in at least one of the first phase noise signal and the second phase noise signal. The detection device of claim 1 .

5. the secondary power system transmits power to one or more electrical equipment; the filter unit includes one or more filters that remove frequency components of the predetermined frequency and frequency components of noise signals due to the electrical equipment. The detection device according to claim 4.

6. The filter unit includes one or more filters that pass a frequency band that is higher than the predetermined frequency and corresponds to the frequency characteristics of inductance coupling in the power transformer. The detection device according to claim 4.

7. the detection unit adds the first phase noise signal and the second phase noise signal, and outputs the detection signal when a signal having an amplitude equal to or greater than a fifth predetermined value is detected in the added signal. The detection device according to claim 4.

8. a primary-side detection device that receives a third AC signal corresponding to a vector sum of AC signals in three-phase power lines in the primary-side power system, and outputs a primary-side detection signal indicating that a breakdown has occurred in a power line in the primary-side power system when detecting a signal in the third AC signal that has an amplitude equal to or greater than a sixth predetermined value and that occurs periodically at predetermined phase intervals; the detection unit receives the primary-side detection signal from the primary-side detection device, and outputs the detection signal when detecting the two signals. The detection device according to claim 4.

9. a sensor unit that receives an AC signal from a power line in a secondary power system that receives low-voltage power obtained by voltage conversion of high-voltage power of a predetermined frequency in a primary power system by a transformer; a filter unit that extracts information on a plurality of phases in which absolute values ​​of positive and negative signal levels are maximum for each cycle of the AC signal based on the AC signal received by the sensor unit; a detection unit that outputs a detection signal indicating that a breakdown has occurred in a power line in the primary-side power system when detecting two signals having amplitudes equal to or greater than a first predetermined value that are synchronized with two phases included in one cycle of the AC signal among the plurality of phases; A detection device comprising:

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