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

Abstract

An insulator deterioration diagnostic device is provided with: a calculation unit (102) for calculating the discharge power of an electrical device having an insulator on the basis of an electric signal based on the output of a single-type sensor that measures the current flowing through a conductor of the electrical device; and a diagnosis unit (105) that diagnoses the deterioration state of the insulator on the basis of the calculated discharge power.

Description

Technical Field

[0001] This disclosure relates to insulator degradation diagnostic techniques. Background Technology

[0002] In electrical equipment such as rotating machinery, equipment failures can sometimes occur due to the deterioration of the insulators used. To prevent such failures, it is important to monitor the deterioration state of the insulators and maintain the electrical equipment to ensure its long-term safe operation. For example, the technology disclosed in Patent Document 1 is a technique for diagnosing the deterioration of insulators in rotating machinery.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-38676 Summary of the Invention

[0006] According to the insulation degradation diagnostic device disclosed in Patent Document 1, there is a problem that multiple types of sensors, such as temperature detection unit, water vapor quantity acquisition unit, and gas measurement unit, are needed to measure multiple physical quantities.

[0007] This disclosure was made to solve such a problem, and its purpose is to provide an insulation degradation diagnosis technique that can diagnose the degradation of the insulation of electrical equipment using a simple structure with fewer types of sensors.

[0008] One aspect of the insulator degradation diagnostic apparatus according to the embodiments of this disclosure includes: a calculation unit that calculates the discharge power of the electrical equipment based on an electrical signal output from a single type of sensor that measures the current flowing in the conductor of the electrical equipment having an insulator; and a diagnostic unit that diagnoses the degradation state of the insulator based on the calculated discharge power.

[0009] The insulation degradation diagnostic apparatus according to the embodiments of this disclosure can diagnose the degradation of the insulation of electrical equipment with a simple structure that uses fewer types of sensors. Attached Figure Description

[0010] Figure 1 This is a diagram illustrating a structural example of an insulator degradation diagnostic device and an insulator degradation diagnostic system.

[0011] Figure 2 It is a partial cross-sectional view of rotating machinery.

[0012] Figure 3 This is a diagram illustrating an example of the circuit structure of a measurement system included in an insulator degradation diagnostic system.

[0013] Figure 4A This is a diagram illustrating a structural example of the hardware of an insulator degradation diagnostic device.

[0014] Figure 4B This is a diagram illustrating a structural example of the hardware of an insulator degradation diagnostic device.

[0015] Figure 5 This is a flowchart of the insulator degradation diagnosis method.

[0016] Figure 6 This is a graph showing the relationship between discharge power and degradation state. Detailed Implementation

[0017] Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, in the drawings, the same or similar symbols are used for the same or similar parts, and repeated descriptions of such parts are omitted. Additionally, in this disclosure, the term "or" is used in a general logical sense unless specifically stated otherwise.

[0018] It is generally known that the insulators of electrical equipment deteriorate due to partial discharge. In the insulator deterioration diagnosis technique disclosed herein, the deterioration state of the insulators of rotating machinery is diagnosed based on information about the discharge current of the partially discharged components exposed in the insulator. This will be explained in more detail below.

[0019] Implementation method 1.

[0020] <Structure>

[0021] Reference Figure 1 This section describes the structure of the insulator degradation diagnostic device and the insulator degradation diagnostic system. Figure 1 This is a diagram illustrating an example of the structure of the insulator degradation diagnostic device 10 and the insulator degradation diagnostic system Sys. (See diagram for details.) Figure 1 As shown, as an example, the insulator degradation diagnostic system Sys. includes a power supply 6 that supplies AC power to the electrical equipment being diagnosed for insulation degradation, an integrating capacitor 9, an insulator degradation diagnostic 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 as electrical signals to the insulator degradation diagnostic device 10. The power supply 6 and the integrating capacitor 9 are the elements constituting the measurement system of the insulator degradation diagnostic system Sys. For a detailed structural example of the measurement system, please refer to... Figure 3 To be described later.

[0022] (Input / output devices)

[0023] The input / output device 20 includes: an input device for receiving operation instructions from an operator; and a display device for displaying diagnostic results via text or images. Examples of the input device include a keyboard or a mouse. Examples of the display device include a liquid crystal display (LCD) or an organic EL (Electroluminescence) display. The input / output device 20 may also be a display with a touch panel that integrates both the input device and the display device.

[0024] (Storage device)

[0025] Storage device 30 is a known storage medium that holds programs or data related to the processing of the insulation degradation diagnostic device 10. As an example, storage device 30 stores discharge degradation relationship data, which will be described later.

[0026] (Insulator Deterioration Diagnostic Device)

[0027] like Figure 1 As shown, the insulator degradation diagnostic device 10 includes an arithmetic unit 102 and a diagnostic unit 105.

[0028] (Computation Department)

[0029] The arithmetic unit 102 includes an electrical signal acquisition unit 103 and a discharge power calculation unit 104. The electrical 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 electrical signal acquisition unit 103 provides 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 object to be measured based on the voltage of the power supply 6 and the voltage of the integrating capacitor 9. Regarding the method for calculating the discharge power, [further details are provided]. Figure 5 The flowchart is described later. The discharge power calculation unit 104 provides the calculated discharge power to the diagnostic unit 105.

[0030] (Diagnostic Department)

[0031] The diagnostic unit 105 receives the discharge power calculated by the discharge power calculation unit 104 from the discharge power calculation unit 104. Additionally, the diagnostic unit 105 obtains discharge degradation relationship information corresponding to the insulator of the object to be diagnosed from the discharge degradation relationship data pre-stored in the storage device 30. The discharge degradation relationship data is as follows... Figure 6The data shown represents the relationship between discharge power and the degradation state of insulating materials. The storage device 30 stores discharge degradation relationship data based on characteristics such as the material or thickness of the insulator. The diagnostic unit 105 obtains the discharge degradation relationship data corresponding to the insulator being diagnosed as discharge degradation relationship information. Furthermore, the discharge degradation relationship data can be represented either in tabular form or mathematically. Based on the received discharge power and the obtained discharge degradation relationship information, the diagnostic unit 105 diagnoses the degradation state of the insulator being diagnosed. The diagnostic unit 105 outputs the diagnostic results to the input / output device 20, which displays the diagnostic results.

[0032] (Measurement system)

[0033] Next, refer to Figure 2 as well as Figure 3 This describes the measurement system of Sys., the insulator degradation diagnostic system. Figure 2 This is a partial cross-sectional view of rotating machinery, used as an example of electrical equipment. More specifically... Figure 2 It is a cross-sectional view of the slotted section of the stator core of rotating machinery. Figure 3 This is a diagram illustrating an example of the circuit structure of the Sys. insulator degradation diagnostic system. More specifically, Figure 3 This diagram shows a circuit for measuring the electrical signal of the discharge power of a group of stator coils in a rotating machine.

[0034] like Figure 2 as well as Figure 3 As shown, the measurement system of the Sys. insulator degradation diagnostic system includes: a power supply 6, which supplies AC power to the rotating machinery; an optical CT 71 (first optical CT), which measures the inflow current into the measurement object part of the rotating machinery; an optical CT 72 (second optical CT), which measures the outflow current from the measurement object part; a differential operation circuit 8, connected to these optical CTs 71 and 72, which outputs an electrical signal corresponding to the difference between the inflow current into the measurement object part and the outflow current from the measurement object part; and an integrating capacitor 9, connected between the output of the differential operation circuit 8 and ground. Figure 3 As shown, the insulator degradation diagnostic device 10 is connected to the connection line (first connection line) that supplies AC power from the power source 6 and the connection line (second connection line) that connects the differential operation circuit 8 and the integrating capacitor 9.

[0035] like Figure 2As shown, a slot is provided in the stator core 1. The stator coil 5, consisting of a stator coil conductor 2, a stator coil insulating component 3, and a stator coil insulating film 4 to prevent corona discharge, is housed in this slot. In this configuration, when a gap exists between the stator coil insulating film 4 and the stator core 1, partial discharge occurs starting from the gap. Hereinafter, taking the stator coil insulating film 4 as an example of an insulator, a method for diagnosing the deterioration of the stator coil insulating film 4 due to partial discharge from this gap will be described.

[0036] exist Figure 3 In this configuration, the stator core 1 is set to ground potential. The stator coil 5 is constructed by connecting N stator coils 5-1, 5-2, 5-3, ..., 5-N in series. One end of the stator coil 5 is connected to the power supply 6. The stator coil 5 receives a voltage from the power supply 6, therefore it is at a high voltage. The other end of the stator coil 5 is grounded. The partial discharge that degrades the stator coil insulation film 4 occurs between the stator core 1 and the stator coil 5.

[0037] As an example, the measurement of the electrical signal is explained as follows: the discharge power of the partial discharge generated between the stator coil 5-1, which is closest to the power supply 6 among the stator coils 5-1 to 5-N constituting the stator coil 5, and the stator core 1 is calculated by the discharge power calculation unit 104. Furthermore, "closest position" as used here means electrically connected to the power supply 6, i.e., directly connected to the power supply 6 without passing through other stator coils.

[0038] The current flowing in stator coil 5 flows in the order of stator coil 5-1, stator coil 5-2, and stator coil 5-3, and then flows through stator coil 5-N to the grounding point. At this time, when a partial discharge occurs between stator coil 5-1 and stator core 1, the discharge current flows from stator coil 5-1 to stator core 1. This discharge current is equal to the difference between the current flowing into stator coil 5-1 from power source 6 and the current flowing out of stator coil 5-1 to stator coil 5-2. Therefore, optical CT71 is used to measure the current flowing into stator coil 5-1, and optical CT72 is used to measure the current flowing out of stator coil 5-1 to stator coil 5-2.

[0039] An optical current transformer (CT) is a sensor for detecting current, consisting of optical fiber and a Faraday element with a magneto-optical effect. The Faraday element allows for the optical detection of magnetism generated by the current, and the detected magnetic information, transmitted through the optical fiber by the light passing through it, can be transmitted to the outside. The transmitted light carries information about the detected magnetism, and the detected magnetism carries information about the current; therefore, current can be detected using an optical CT and the detected current can be transmitted as an optical signal. This disclosure presents a technique for diagnosing insulator degradation using only optical CTs. That is, unlike existing technologies that use multiple types of sensors, only optical CT71 and optical CT72 are used as single-type sensors.

[0040] In this disclosure, two optical CT71 and optical CT72 are used. As an example, such as Figure 3 As shown, the first optical CT 71 is positioned upstream of the stator coil 5-1, which is the part to be measured, and the second optical CT 72 is positioned downstream of the stator coil 5-1, separated by the stator coil 5-1. Each optical CT 71 and optical CT 72 is arranged such that a conductor-made connecting line that connects the stator coil 5-1 and the power supply 6 or the stator coil 5-2 is surrounded by a Faraday element.

[0041] Each optical CT71 and optical CT72 inputs an optical signal based on the measured current to the differential operation circuit 8. The differential operation circuit 8 includes two photoelectric conversion circuits and a differential operation circuit that calculates the difference between the electrical signals output from each photoelectric conversion circuit. The photoelectric conversion circuits can be constructed from photoelectric conversion elements, and the differential operation circuit can be constructed from operational amplifiers. The differential operation circuit 8 outputs an electrical signal equivalent to the difference between the two input optical signals.

[0042] The electrical signal output from the differential operational circuit 8 is directed towards ground potential via the integrating capacitor 9. Here, the electrostatic capacitance of the integrating capacitor 9 is known.

[0043] The insulator degradation diagnostic device 10 is connected to the integrating capacitor 9 and the power supply 6. The electrical signal acquisition unit 103 of the arithmetic unit 102 of the insulator degradation diagnostic device 10 acquires two electrical signals: the voltage of the integrating capacitor 9 and the voltage of the power supply 6.

[0044] The method for obtaining the aforementioned electrical signal can be applied to situations other than the stator coil 5-1 closest to the high-voltage end by changing the connection position of optical CT71 or optical CT72. It can also calculate the total discharge power generated between two or more stator coils and the stator core 1. In other words, the first optical CT71 and the second optical CT72 can be configured to be separated by any one or more stator coils.

[0045] (hardware)

[0046] Next, refer to Figure 4A as well as Figure 4B This section describes an example of the hardware structure of the insulator degradation diagnostic device 10. Each function of the insulator degradation diagnostic device 10 is implemented through a processing circuitry. The processing circuitry can be, for example,... Figure 4A The dedicated processing circuit 100a shown can also be as follows: Figure 4B The processor 100b shown executes the program stored in memory 100c.

[0047] When the processing circuitry is a dedicated processing circuitry 100a, the corresponding components include, for example, a single circuit, a composite circuit, a programmable processor, a parallel programmable processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. The function of the insulator degradation diagnostic device 10 can be implemented using multiple independent processing circuits, or it can be implemented centrally using a single processing circuit.

[0048] When the processing circuitry is processor 100b, the function of the insulator degradation diagnostic device 10 is implemented through software, firmware, or a combination of software and firmware. The software and firmware are described as programs and stored in memory 100c. Processor 100b implements the function of the insulator degradation diagnostic device 10 by reading and executing the programs stored in memory 100c. Examples of memory 100c include non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read-Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), and EEPROM (Electrically Erasable Programmable Read-Only Memory), as well as disks, floppy disks, optical disks, compact disks, mini-disks, and DVDs. Memory 100c can also be implemented as the same device as storage device 30.

[0049] Alternatively, some of the functions of the insulator degradation diagnostic device 10 can be implemented using dedicated hardware, while other functions can be implemented using software or firmware. In this way, the processing circuit can realize the functions of the insulator degradation diagnostic device 10 through hardware, software, firmware, or a combination thereof.

[0050] <Action>

[0051] Next, refer to Figure 5 This section explains an example of the operation of the insulator degradation diagnostic device 10 and the insulator degradation diagnostic system Sys. Taking a rotating machine as an example of electrical equipment, the case of diagnosing the degradation state of the insulator of the rotating machine will be explained.

[0052] In step ST1, the diagnostic unit 105 receives, via the input / output device 20, material information related to the characteristics of the insulator of the object to be diagnosed, and information on the operating conditions of the rotating machinery including the insulator of the object to be diagnosed. The material information related to the characteristics of the insulator refers, for example, in the case of the stator coil insulation film 4 being the object to be diagnosed, information such as the material composition and thickness of the stator coil insulation film 4. Additionally, the information on the operating conditions of the rotating machinery includes, for example, information on the voltage and frequency of the AC power supply applied to the rotating machinery, and information on the electrostatic capacitance of the integrating capacitor 9. Furthermore, the diagnostic unit 105 obtains discharge degradation relationship information corresponding to the received material information of the insulator from the discharge degradation relationship data stored in the storage device 30.

[0053] In step ST2, optical CT71 and optical CT72 are used to measure the inflow current to and outflow current from the stator coils 5 (5-1, 5-2, ..., 5-N). This measurement can also be performed by an operator during diagnosis, placing the optical CT71 upstream of the stator coil 5 to be measured, such as stator coil 5-1, and the optical CT72 downstream. Alternatively, the optical CT71 can be pre-positioned upstream of each stator coil 5, and the optical CT72 pre-positioned downstream, thus always performing the diagnosis. To measure any one stator coil 5, the optical CT71 and optical CT72 are positioned close to the stator coil 5 to be measured. The differential operation circuit 8 outputs an electrical signal corresponding to the difference between the inflow and outflow currents, and the integrating capacitor 9 accumulates a charge based on the electrical signal output from the differential operation circuit 8. The electrical signal acquisition unit 103 of the insulator degradation diagnostic device 10 acquires the voltage of the integrating capacitor 9 and the voltage of the power supply 6. The electrical signal acquisition unit 103 provides the acquired voltage of the integrating capacitor 9 and the voltage of the power supply 6 to the discharge power calculation unit 104.

[0054] In step ST3, the discharge power calculation unit 104 calculates the discharge power of the object to be measured based on the voltage of the power supply 6 and the voltage of the integrating capacitor 9, according to the VQ Lissajous method. Here, a method for calculating the discharge power of a partial discharge generated between the stator coil 5-1 and the stator core 1 is illustrated by way of example.

[0055] When the voltage in the integrating capacitor 9 is set to Vm and the electrostatic capacitance of the integrating capacitor 9 is set to Cm, the charge Qm accumulated in the integrating capacitor 9 and the current Im(t) flowing in the integrating capacitor 9 can be expressed by the following equations (1) and (2), respectively.

[0056]

[0057]

[0058] The current flowing in 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 and the stator core 1 closest to the power source 6 is equal to the voltage Vs of the power source 6. Therefore, the discharge power Ps(t) of the partial discharge generated between the stator coil 5-1 and the stator core 1 closest to the power source is as shown in equation (3).

[0059]

[0060] Therefore, if the frequency of power supply 6 is set to 1 / T, the average discharge power Ps generated between stator coil 5-1 and stator core 1 in the AC waveform can be represented by the following formula (4).

[0061]

[0062] The average discharge power Ps calculated by equation (4) is equivalent to the area of ​​a Lissajous figure based on charge and voltage.

[0063] In this way, by using an integrating capacitor 9 with a known electrostatic capacitance, 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 generated between the stator coil 5-1 and the stator core 1. The discharge power calculation unit 104 provides the calculated discharge power to the diagnostic unit 105.

[0064] In step ST4, the diagnostic unit 105 diagnoses the deterioration state of the stator coil insulation film 4 used in the stator coil 5-1 based on the discharge power supplied from the discharge power calculation unit 104.

[0065] As in Figure 6 As illustrated, the degradation state of the stator coil insulation film 4 depends on the discharge power of the exposed portions of the stator coil insulation film 4. Figure 6 The relationship can be obtained through sampling tests in the laboratory. The stator coil insulation film 4 is exposed to partial discharge in a laboratory environment, and the results of obtaining the correlation between the degradation state of the stator coil insulation film 4 and the discharge power of the partial discharge are stored in the storage device 30. The diagnostic unit 105 retrieves information corresponding to the input information from the storage device 30 based on the input information from the input device provided in the input / output device 20. Figure 6 Information on the relationship between discharge degradation.

[0066] The diagnostic unit 105 diagnoses the degradation state of the stator coil insulation coating 4 based on information about the discharge power of the insulating components of the object being diagnosed and information about the discharge degradation relationship obtained from the storage device 30. For example... Figure 6 As shown, the higher the discharge power, the greater the deterioration, meaning the condition of the stator coil insulation film 4 becomes worse.

[0067] In step ST5, the diagnostic unit 105 outputs the diagnostic results to the input / output device 20, and the output device of the input / output device 20 displays the diagnostic results.

[0068] According to the above description, the insulation degradation diagnostic device 10 or the insulation degradation diagnostic system Sys. calculates the discharge of electrical equipment with insulators based on the measurement results of optical CT71 and optical CT72, which are single-type sensors. Therefore, the degradation of insulators can be diagnosed with a simpler structure than before.

[0069] Furthermore, by pre-configuring optical CT71 and optical CT72 to the electrical equipment and maintaining an electrical signal, online diagnosis can be performed without stopping the electrical equipment. Additionally, in the above description, the integrating capacitor 9 is connected to the output of the differential operation circuit 8, and the voltage of the integrating capacitor 9 is input to the insulator deterioration diagnostic device 10 to calculate the discharge power of the measured object. However, instead of the integrating capacitor 9, a numerical calculation circuit that performs real-time integration calculations can be provided, with the output of the differential operation circuit 8 input to the numerical calculation circuit, and the output of the numerical calculation circuit input to the insulator deterioration diagnostic device 10.

[0070] Furthermore, it is possible to combine implementation methods or appropriately modify or omit various implementation methods.

[0071] Industrial availability

[0072] The insulation degradation diagnostic device disclosed herein can be used as a device for diagnosing the degradation of insulations used in electrical equipment such as rotating machinery.

[0073] (Explanation of reference numerals in the attached image)

[0074] 1: Stator core; 2: Stator coil conductor; 3: Stator coil insulation components; 4: Stator coil insulation coating; 5 (5-1 to 5-N): Stator coil; 6: Power supply; 71, 72: Optical CT; 8: Differential operational circuit; 9: Integrating capacitor; 10: Insulator deterioration diagnostic device; 20: Input / output device; 30: Storage device; 100a: Processing circuit; 100b: Processor; 100c: Memory; 102: Arithmetic unit; 103: Electrical signal acquisition unit; 104: Discharge power arithmetic unit; 105: Diagnostic unit.

Claims

1. An insulator degradation diagnostic device, comprising: The arithmetic unit calculates the discharge power of the electrical equipment based on an electrical signal, said electrical signal being the output of a single-type sensor that measures the current flowing in the conductor of the electrical equipment having an insulator; and The diagnostic department diagnoses the deterioration state of the insulator based on the calculated discharge power.

2. The insulator degradation diagnostic device according to claim 1, wherein, The diagnostic department: Accept material information relating to the properties of the insulator. From pre-obtained discharge degradation relationship data representing the relationship between discharge power and the degradation state of insulating materials, discharge degradation relationship information corresponding to material information related to the properties of the insulator is obtained. Based on the calculated discharge power and the obtained discharge degradation relationship information, the degradation state of the insulator is diagnosed.

3. The insulator degradation diagnostic device according to claim 1 or 2, wherein, The computation unit calculates the discharge power of the electrical device based on the area of ​​a Lissajous figure based on charge and voltage.

4. An insulator degradation diagnostic system, wherein, The single type of sensor mentioned is optical CT. The insulator degradation diagnostic system has the following features: The power source supplies alternating current to the electrical equipment. The first optical CT measures the inflow current into the measurement object of the electrical equipment; The second optical CT measures the outflow current from the measured object area; A differential operation circuit is connected to the first optical CT and the second optical CT, and outputs an electrical signal equivalent to the difference between the inflow current and the outflow current. An integrating capacitor is connected to the differential operation circuit and ground; as well as The insulator degradation diagnostic device according to any one of claims 1 to 3 is connected to a first connection line supplied with the AC power and a second connection line connecting the differential operation circuit and the integrating capacitor.

5. The insulator degradation diagnostic system according to claim 4, wherein, The electrical equipment is rotating machinery, comprising: at least one stator coil having a stator coil insulating film to prevent corona discharge, and an iron core housing the at least one stator coil. The discharge power of the electrical equipment is the discharge power between the stator coil insulation film and the iron core.

6. The insulator degradation diagnostic system according to claim 5, wherein, The first optical CT and the second optical CT are configured such that they are separated by one or more stator coils contained in the at least one stator coil.

7. The insulator degradation diagnostic system according to claim 6, wherein, The one or more stator coils mentioned above are the single stator coils that are directly connected to the power source and are located closest to the power source among the at least one stator coils.

8. A method for diagnosing insulator degradation, utilizing an insulator degradation diagnosis device having a calculation unit and a diagnosis unit, comprising: The step of the calculation unit calculating the discharge power of the electrical equipment based on the electrical signal includes, wherein... The electrical signal is an output signal based on a single type of sensor that measures the current flowing in the conductor of the electrical equipment having an insulator. as well as The diagnostic unit diagnoses the deterioration state of the insulator based on the calculated discharge power.

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