Insulator deterioration diagnosing device, insulator deterioration diagnosing system, and insulator deterioration diagnosing method

Abstract

This insulator deterioration diagnosing device comprises: a calculating unit (102) that calculates the discharge power of an electrical appliance having an insulator, from an electrical signal based on an output of a single type of sensor that measures the current flowing through a conductor of the electrical appliance; and a diagnosing unit (105) that diagnoses the state of deterioration of the insulator on the basis of the calculated discharge power.

Description

Insulator Deterioration Diagnostic Device, Insulator Deterioration Diagnostic System, and Insulator Deterioration Diagnostic Method

[0001] The present disclosure relates to a technique for diagnosing degradation of an insulator.

[0002] In electrical equipment such as rotating machines, deterioration of the insulators used can cause failure of the electrical equipment. In order to prevent failure of the electrical equipment, it is important to understand the deterioration state of the insulators and perform maintenance on the electrical equipment so that the electrical equipment can operate safely over the long term. For example, Patent Document 1 discloses a technology for diagnosing the deterioration of insulators in rotating machines.

[0003] JP 2022-38676 A

[0004] The insulation deterioration diagnosis device disclosed in Patent Document 1 has a problem in that it is necessary to measure multiple physical quantities using multiple types of sensors such as temperature detection means, water vapor amount acquisition means, and gas measurement means.

[0005] The present disclosure has been made to solve such problems, and aims to provide an insulator deterioration diagnosis technology that can diagnose the deterioration of insulators in electrical equipment using a simple configuration with a smaller number of sensor types.

[0006] One aspect of an insulator degradation diagnosis device according to an embodiment of the present disclosure includes a calculation unit that calculates the discharge power of an electrical device having an insulator from an electrical signal based on the output of a single type of sensor that measures the current flowing through a conductor of the electrical device, and a diagnosis unit that diagnoses the degradation state of the insulator based on the calculated discharge power.

[0007] According to the insulator deterioration diagnosis device according to the embodiment of the present disclosure, it is possible to diagnose the deterioration of the insulator of an electrical device with a simple configuration having a smaller number of types of sensors.

[0008] FIG. 1 is a diagram illustrating an example of the configuration of an insulator degradation diagnosis device and an insulator degradation diagnosis system. FIG. 2 is a partial cross-sectional view of a rotating machine. FIG. 3 is a diagram illustrating an example of the configuration of a circuit of a measurement system provided in an insulator degradation diagnosis system. FIG. 4 is a diagram illustrating an example of the configuration of the hardware of an insulator degradation diagnosis device. FIG. 5 is a diagram illustrating an example of the configuration of the hardware of an insulator degradation diagnosis device. FIG. 6 is a flowchart of an insulator degradation diagnosis method. FIG. 7 is a diagram illustrating the relationship between discharge power and degradation state.

[0009] Various embodiments of the present disclosure will be described in detail below with reference to the drawings. In the drawings, identical or similar parts are designated by identical or similar reference numerals, and redundant explanations of such parts will be omitted. In addition, in this disclosure, the term "or" is used to mean an inclusive logical OR unless otherwise specified.

[0010] It is generally known that insulators in electrical equipment deteriorate due to partial discharges. The insulator deterioration diagnosis technology disclosed herein diagnoses the deterioration state of insulators in rotating machines based on information on discharge power of partial discharges to which the insulators are exposed. This technology will be described in more detail below.

[0011] Embodiment 1. <Configuration> The configuration of an insulator degradation diagnosis device and an insulator degradation diagnosis system will be described with reference to FIG. 1 . FIG. 1 is a diagram showing an example configuration of an insulator degradation diagnosis device 10 and an insulator degradation diagnosis system Sys. As shown in FIG. 1 , the insulator degradation diagnosis system Sys. includes, as an example, a power supply 6 that supplies AC power to an electrical device that is the target of insulation degradation diagnosis, an integrating capacitor 9, an insulator degradation diagnosis device 10, an input / output device 20, and a storage device 30. The voltage of the power supply 6 and the voltage of the integrating capacitor 9 are input to the insulator degradation diagnosis device 10 as electrical signals. The power supply 6 and the integrating capacitor 9 are elements that constitute a measurement system of the insulator degradation diagnosis system Sys. A detailed example configuration of the measurement system will be described later with reference to FIG. 3 .

[0012] (Input / Output Device) The input / output device 20 includes an input device that accepts operation instructions from an operator and a display device that displays diagnostic results in the form of text, images, or the like. Examples of the input device include a keyboard or a mouse. Examples of the display device include a liquid crystal display device or an organic EL (Electro Luminescence) display. The input / output device 20 may be a touch panel display that integrates the input device and display device.

[0013] (Storage Device) The storage device 30 is a known storage medium that stores programs or data related to the processing of the insulator deterioration diagnosis device 10. The storage device 30 stores, as an example, discharge deterioration related data, which will be described later.

[0014] (Insulator Deterioration Diagnostic Device) As shown in FIG. 1 , the insulator deterioration diagnostic device 10 includes a calculation unit 102 and a diagnostic unit 105 .

[0015] (Calculation Unit) The calculation unit 102 includes an electric signal acquisition unit 103 and a discharge power calculation unit 104. The electric signal acquisition unit 103 is a functional unit that acquires the voltage of the power supply 6 and the voltage of the integrating capacitor 9. The electric signal acquisition unit 103 supplies the acquired voltage of the power supply 6 and the voltage of the integrating capacitor 9 to the discharge power calculation unit 104. The discharge power calculation unit 104 calculates the discharge power of the measurement object from the voltage of the power supply 6 and the voltage of the integrating capacitor 9. A method for calculating the discharge power will be described later with reference to the flowchart of FIG. 5 . The discharge power calculation unit 104 supplies the calculated discharge power to the diagnosis unit 105.

[0016] (Diagnosis Unit) The diagnosis unit 105 receives the discharge power calculated by the discharge power calculation unit 104 from the discharge power calculation unit 104. The diagnosis unit 105 also acquires, from the storage device 30, discharge degradation relationship information corresponding to the insulator to be diagnosed from among the discharge degradation relationship data pre-stored in the storage device 30. The discharge degradation relationship data is data representing the relationship between the discharge power and the degradation state of the insulating material, as shown in FIG. 6. The storage device 30 stores discharge degradation relationship data according to characteristics such as the material or thickness of the insulator, and the diagnosis unit 105 acquires the discharge degradation relationship data corresponding to the insulator to be diagnosed as the discharge degradation relationship information. The discharge degradation relationship data may be represented in a table format or may be expressed by a mathematical formula. The diagnosis unit 105 diagnoses the degradation state of the insulator to be diagnosed based on the received discharge power and the acquired discharge degradation relationship information. The diagnosis unit 105 outputs the diagnosis result to the input / output device 20, and the diagnosis result is displayed by the input / output device 20.

[0017] (Measurement System) Next, the measurement system of the insulator degradation diagnosis system Sys. will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a partial cross-sectional view of a rotating machine as an example of electrical equipment. More specifically, Fig. 2 is a cross-sectional view of a slot portion of a stator core of a rotating machine. Fig. 3 is a diagram showing an example of the circuit configuration of the measurement system of the insulator degradation diagnosis system Sys. More specifically, Fig. 3 shows an electrical signal measurement circuit for acquiring the discharge power of a group of stator coils for one phase of the rotating machine.

[0018] 2 and 3, the measurement system of the insulation degradation diagnosis system Sys. includes a power supply 6 that supplies AC power to the rotating machine, an optical CT 71 (first optical CT) that measures the inflow current flowing into a measurement target location of the rotating machine, an optical CT 72 (second optical CT) that measures the outflow current flowing out of the measurement target location, a differential calculation circuit 8 connected to the optical CT 71 and the optical CT 72 and that outputs an electrical signal corresponding to the difference between the inflow current flowing into the measurement target location and the outflow current flowing out of the measurement target location, and an integrating capacitor 9 connected between the output of the differential calculation circuit 8 and ground. As shown in Fig. 3, an insulator degradation diagnosis device 10 is connected to a connection line (first connection line) through which AC power is supplied from the power supply 6 and a connection line (second connection line) that connects the differential calculation circuit 8 and the integrating capacitor 9.

[0019] As shown in Figure 2, a stator core 1 has slots. These slots house stator coils 5, each composed of a stator coil conductor 2, a stator coil insulating member 3, and a stator coil insulating coating 4 that prevents corona discharge. In this structure, if a gap exists between the stator coil insulating coating 4 and the stator core 1, partial discharge will occur starting from the gap. Below, we will describe a method for diagnosing deterioration of the stator coil insulating coating 4 due to partial discharge in the gap, assuming that the stator coil insulating coating 4 is used as an example of an insulator.

[0020] In Fig. 3, the stator core 1 is set to ground potential. The stator coil 5 is configured by serially connecting N stator coils 5-1, 5-2, 5-3, ... 5-N, and one end of the stator coil 5 is connected to a power source 6. A voltage is applied to the stator coil 5 from the power source 6, so the stator coil 5 is at a high voltage. The other end of the stator coil 5 is grounded. Partial discharges that deteriorate the stator coil insulation coating 4 occur between the stator core 1 and the stator coil 5.

[0021] As an example, the measurement of an electrical signal for calculating, by the discharge power calculation unit 104, the discharge power of a partial discharge occurring between the stator core 1 and the stator coil 5-1, which is closest to the power supply 6 among the stator coils 5-1 to 5-N that make up the stator coil 5. Note that "close" here means that the stator coil 5-1 is electrically connected closer to the power supply 6, that is, that the stator coil 5-1 is directly connected to the power supply 6 without going through another stator coil.

[0022] The current flowing through the stator coil 5 passes through the stator coil 5-1, stator coil 5-2, and stator coil 5-3 in that order, and then flows through the stator coil 5-N before reaching the ground. At this time, if a partial discharge occurs between the stator coil 5-1 and the stator core 1, a discharge current flows from the stator coil 5-1 to the stator core 1. This discharge current is equal to the difference between the current flowing into the stator coil 5-1 from the power supply 6 and the current flowing out from the stator coil 5-1 to the stator coil 5-2. Therefore, the optical CT 71 is used to measure the current flowing into the stator coil 5-1, and the optical CT 72 is used to measure the current flowing out from the stator coil 5-1 to the stator coil 5-2.

[0023] An optical current transformer (CT) is a sensor for detecting electric current, composed of an optical fiber and a Faraday element having a magneto-optical effect. The Faraday element can optically detect magnetism generated by electric current, and the detected magnetic information can be transmitted to the outside by propagating the detected light through the optical fiber. Since the propagating light carries information about the detected magnetism, and the detected magnetism carries information about the electric current, an optical CT can be used to detect electric current and propagate the detected current as an optical signal. This disclosure discloses a technology for diagnosing the deterioration of an insulator using only an optical CT. That is, instead of using multiple types of sensors as in conventional technology, only an optical CT 71 and an optical CT 72 are used as a single type of sensor.

[0024] In this disclosure, two optical CTs, an optical CT 71 and an optical CT 72, are used. As an example, as shown in Fig. 3, the first optical CT 71 is arranged upstream of the stator coil 5-1, which is the measurement target, and the second optical CT 72 is arranged downstream of the first optical CT 71, with the stator coil 5-1 sandwiched between them. Each of the optical CTs 71 and 72 is arranged so that the Faraday elements surround a connecting line made of a conductor that connects the stator coil 5-1 to the power supply 6 or the stator coil 5-2.

[0025] Each of the optical CTs 71 and 72 inputs an optical signal based on the measured current to the differential calculation circuit 8. The differential calculation circuit 8 includes two photoelectric conversion circuits and a differential calculation circuit that calculates the difference between the electrical signals output from each photoelectric conversion circuit. The photoelectric conversion circuits can be configured using photoelectric conversion elements, and the differential calculation circuit can be configured using an operational amplifier. The differential calculation circuit 8 outputs an electrical signal corresponding to the difference between the two input optical signals.

[0026] The electrical signal output from the difference calculation circuit 8 is directed to the ground potential via the integrating capacitor 9. The capacitance of the integrating capacitor 9 is known.

[0027] The insulator deterioration diagnosis device 10 is connected to an integrating capacitor 9 and a power supply 6, and the electrical signal acquisition unit 103 of the calculation unit 102 of the insulator deterioration diagnosis device 10 acquires two electrical signals: the voltage of the integrating capacitor 9 and the voltage of the power supply 6.

[0028] The above-described method of acquiring an electrical signal can be applied to cases other than the stator coil 5-1 closest to the high-voltage end by changing the connection position of the optical CT 71 or optical CT 72, and it is also possible to find the total power of the discharge power generated between two or more stator coils and the stator core 1. In other words, the first optical CT 71 and the second optical CT 72 may be arranged so as to sandwich any one or more stator coils therebetween.

[0029] (Hardware) Next, an example of the hardware configuration of the insulator degradation diagnosis device 10 will be described with reference to Figures 4A and 4B. Each function of the insulator degradation diagnosis device 10 is realized by a processing circuitry. The processing circuitry may be a dedicated processing circuit 100a as shown in Figure 4A, or a processor 100b that executes a program stored in a memory 100c as shown in Figure 4B.

[0030] When the processing circuitry is a dedicated processing circuit 100a, the dedicated processing circuit 100a may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination thereof. The functions of the insulation degradation diagnosis device 10 may be realized by a plurality of separate processing circuits, or the functions of the insulation degradation diagnosis device 10 may be realized together by a single processing circuit.

[0031] When the processing circuitry is a processor 100b, the functions of the insulator degradation diagnosis device 10 are realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in the memory 100c. The processor 100b realizes the functions of the insulator degradation diagnosis device 10 by reading and executing the programs stored in the memory 100c. Examples of the memory 100c include non-volatile or volatile semiconductor memories such as random access memory (RAM), read-only memory (ROM), flash memory, erasable programmable read-only memory (EPROM), and electrically erasable programmable read-only memory (EEPROM), as well as magnetic disks, flexible disks, optical disks, compact disks, minidisks, and DVDs. The memory 100c may be realized as the same device as the storage device 30.

[0032] Note that some of the functions of the insulator degradation diagnosis device 10 may be realized by dedicated hardware, and other functions may be realized by software or firmware. In this way, the processing circuit can realize the functions of the insulator degradation diagnosis device 10 by hardware, software, firmware, or a combination of these.

[0033] <Operation> Next, an example of the operation of the insulator degradation diagnosis device 10 and the insulator degradation diagnosis system Sys. will be described with reference to Fig. 5. Assuming a rotating machine as an example of electrical equipment, the description will be given in conjunction with a case where the deterioration state of the insulators of the rotating machine is diagnosed.

[0034] In step ST1, the diagnosis unit 105 receives, as inputs via the input / output device 20, material information relating to the characteristics of the insulator to be diagnosed and information on the operating conditions of the rotating machine including the insulator to be diagnosed. For example, if the stator coil insulating coating 4 is the diagnostic target, the material information relating to the characteristics of the insulator is information on the material composition, thickness, etc. of the stator coil insulating coating 4. Furthermore, the information on the operating conditions of the rotating machine includes, for example, information on the voltage and frequency of the AC power supply applied to the rotating machine and information on the capacitance of the integrating capacitor 9. Furthermore, the diagnosis unit 105 acquires discharge degradation-related information corresponding to the received material information of the insulator from the discharge degradation-related data stored in the storage device 30.

[0035] In step ST2, the current flowing into and out of the stator coils 5 (5-1, 5-2, ..., 5-N) is measured using the optical CT 71 and the optical CT 72. This measurement may be performed by an operator placing the optical CT 71 upstream of the stator coil 5 to be measured, for example, the stator coil 5-1, and the optical CT 72 downstream of the stator coil 5 to be measured during diagnosis. Alternatively, the optical CT 71 may be placed upstream of each stator coil 5 and the optical CT 72 downstream of each stator coil 5 in advance, allowing for continuous diagnosis. To measure any one stator coil 5, the optical CT 71 and the optical CT 72 are placed close to the stator coil 5 to be measured. The differential calculation circuit 8 outputs an electrical signal corresponding to the difference between the inflow current and the outflow current, and the integrating capacitor 9 accumulates charge due to the electrical signal output from the differential calculation circuit 8. The electrical signal acquisition unit 103 of the insulator degradation diagnosis device 10 acquires the voltage of the integrating capacitor 9 and the voltage of the power supply 6. The electrical signal acquisition unit 103 supplies the acquired voltage of the integrating capacitor 9 and the voltage of the power supply 6 to the discharge power calculation unit 104 .

[0036] In step ST3, the discharge power calculation unit 104 calculates the discharge power of the measurement object based on the V-Q Lissajous method from the voltage of the power supply 6 and the voltage of the integrating capacitor 9. Here, an example of a method for calculating the discharge power of partial discharge occurring between the stator coil 5-1 and the stator core 1 is shown.

[0037] If the voltage at the integrating capacitor 9 is Vm and the capacitance of the integrating capacitor 9 is Cm, the charge Qm stored in the integrating capacitor 9 and the current Im(t) flowing through the integrating capacitor 9 can be expressed by the following equations (1) and (2), respectively.

[0038] The current flowing through the integrating capacitor 9 is equal to the discharge current flowing between the stator coil 5-1 and the stator core 1. The potential difference between the stator coil 5-1 closest to the power supply 6 and the stator core 1 is equal to the voltage Vs of the power supply 6, so the discharge power Ps(t) of the partial discharge occurring between the stator coil 5-1 closest to the power supply and the stator core 1 is given by the following equation (3):

[0039] Therefore, if the frequency of the power supply 6 is 1 / T, the average discharge power Psbar generated between the stator coil 5-1 and the stator core 1 in an AC waveform can be expressed by the following equation (4).

[0040] The average discharge power Ps calculated by equation (4) corresponds to the area of ​​the Lissajous figure formed by the charge and voltage.

[0041] In this way, by using the integrating capacitor 9 having a known capacitance and measuring the voltage of the integrating capacitor 9 and the voltage of the power supply 6, it is possible to calculate the discharge power of the partial discharge that occurs between the stator coil 5-1 and the stator core 1. The discharge power calculation unit 104 supplies the calculated discharge power to the diagnosis unit 105.

[0042] In step ST4, the diagnosing unit 105 diagnoses the deterioration state of the stator coil insulating coating 4 used in the stator coil 5-1 based on the discharge power supplied from the discharge power calculating unit 104.

[0043] The degradation state of the stator coil insulating coating 4 depends on the discharge power of partial discharge to which the stator coil insulating coating 4 is exposed, as shown in Fig. 6 as an example. The relationship shown in Fig. 6 can be obtained by sample testing in a laboratory. The storage device 30 stores the results of exposing the stator coil insulating coating 4 to partial discharge in a laboratory environment and obtaining a correlation between the degradation state of the stator coil insulating coating 4 and the discharge power of partial discharge. Based on input information from an input device included in the input / output device 20, the diagnosis unit 105 obtains discharge degradation relationship information such as that shown in Fig. 6 from the storage device 30 that corresponds to the input information.

[0044] The diagnosis unit 105 diagnoses the degradation state of the stator coil insulating coating 4 based on information on the discharge power of the insulating member to be diagnosed and information related to discharge degradation acquired from the storage device 30. As shown in Fig. 6, the higher the discharge power, the more advanced the degradation state, i.e., the worse the condition of the stator coil insulating coating 4.

[0045] In step ST5, the diagnosis unit 105 outputs the diagnosis result to the input / output device 20, and the output device of the input / output device 20 displays the diagnosis result.

[0046] According to the insulator degradation diagnosis device 10 or the insulator degradation diagnosis system Sys. described above, the discharge of an electrical device having an insulator is calculated based on the measurement results of the optical CT 71 and the optical CT 72, which are a single type of sensor, so that the deterioration of the insulator can be diagnosed with a simpler configuration than conventional methods.

[0047] Furthermore, by arranging the optical CTs 71 and 72 in the electrical equipment in advance and constantly transmitting electrical signals, it is possible to perform online diagnosis without shutting down the electrical equipment. In the above explanation, the integrating capacitor 9 is connected to the output of the differential calculation circuit 8, and the voltage of the integrating capacitor 9 is input to the insulator deterioration diagnosis device 10 to calculate the discharge power of the object to be measured, but instead of the integrating capacitor 9, a numerical calculation circuit that performs real-time integration calculations may be provided, and the output of the differential calculation circuit 8 may be input to the numerical calculation circuit, and the output of the numerical calculation circuit may be input to the insulator deterioration diagnosis device 10.

[0048] It is possible to combine the embodiments, and to modify or omit each embodiment as appropriate.

[0049] The insulator deterioration diagnosis device of the present disclosure can be used as a device for diagnosing the deterioration of insulators used in electrical equipment such as rotating machines.

[0050] 1 stator core, 2 stator coil conductor, 3 stator coil insulating member, 4 stator coil insulating coating, 5 (5-1 to 5-N) stator coil, 6 power supply, 71, 72 optical CT, 8 differential calculation circuit, 9 integrating capacitor, 10 insulator deterioration diagnosis device, 20 input / output device, 30 storage device, 100a processing circuit, 100b processor, 100c memory, 102 calculation unit, 103 electrical signal acquisition unit, 104 discharge power calculation unit, 105 diagnosis unit.

Claims

1. An insulator degradation diagnosis device comprising: a calculation unit that calculates the discharge power of an electrical device having an insulator from an electrical signal based on the output of a single type of sensor that measures the current flowing through a conductor of the electrical device; and a diagnosis unit that diagnoses the degradation state of the insulator based on the calculated discharge power.

2. The insulator deterioration diagnosis device of claim 1, wherein the diagnosis unit receives material information relating to the characteristics of the insulator, acquires discharge deterioration relationship information corresponding to the material information relating to the characteristics of the insulator from discharge deterioration relationship data that represents the relationship between previously acquired discharge power and the deterioration state of the insulating material, and diagnoses the deterioration state of the insulator from the calculated discharge power and the acquired discharge deterioration relationship information.

3. An insulator deterioration diagnosis device according to claim 1 or 2, wherein the calculation unit calculates the discharge power of the electrical equipment from an area of ​​a Lissajous figure formed by charge and voltage.

4. An insulation degradation diagnosis system comprising: a power source wherein the single type of sensor is an optical CT; a first optical CT that measures an inflow current flowing into a measurement target portion of the electrical equipment; a second optical CT that measures an outflow current flowing out of the measurement target portion; a differential calculation circuit connected to the first optical CT and the second optical CT and that outputs an electrical signal corresponding to the difference between the inflow current and the outflow current; an integrating capacitor connected to the differential calculation circuit and ground; and an insulation degradation diagnosis device according to any one of claims 1 to 3, connected to a first connecting line through which the AC power is supplied and a second connecting line connecting the differential calculation circuit and the integrating capacitor.

5. An insulation deterioration diagnosis system according to claim 4, wherein the electrical equipment is a rotating machine having at least one stator coil with a stator coil insulating coating that prevents corona discharge and an iron core that houses the at least one stator coil, and the discharge power of the electrical equipment is the discharge power between the stator coil insulating coating and the iron core.

6. An insulation deterioration diagnosis system as described in claim 5, wherein the first optical CT and the second optical CT are arranged so as to sandwich any one or more stator coils included in the at least one stator coil.

7. The insulation degradation diagnosis system according to claim 6, wherein the any one or more stator coils is a single stator coil that is directly connected to the power source and is located closest to the power source among the at least one stator coil.

8. An insulator deterioration diagnosis method using an insulator deterioration diagnosis device having a calculation unit and a diagnosis unit, comprising: a step in which the calculation unit calculates the discharge power of an electrical equipment having an insulator from an electrical signal based on the output of a single type of sensor that measures a current flowing through a conductor of the electrical equipment; and a step in which the diagnosis unit diagnoses the deterioration state of the insulator based on the calculated discharge power.

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