JP6960880B2 - Computer system for evaluating electric power equipment and its method - Google Patents

Description

The present invention relates to a computer system for evaluating an electric power device, and more particularly to a computer system that measures a discharge signal generated in an electric power cable and diagnoses an insulation defect of the electric power cable, and a method thereof.

Diagnosis of electric power equipment is important for stable operation of, for example, an electric power system and an electric power system in a predetermined area such as a factory or a building. On the other hand, the life of electric power equipment is long, the environment used for each of multiple electric power equipment is different, and there are various factors in the mechanism of deterioration of electric power equipment. It is not easy to diagnose the abnormality of. Therefore, a system that supports the diagnosis of electric power equipment has been proposed.

For example, Patent Document 1 describes the strength of the detection signal of the partial discharge sensor in the field monitoring device for the purpose of obtaining a partial discharge remote monitoring device that can efficiently measure even intermittent discharge and can monitor for 24 hours at low cost. A system is described in which a detection signal having a detection signal equal to or higher than the reference strength is transmitted to a monitoring terminal via a communication means when the strength of the detection signal is equal to or higher than the reference strength of the comparison circuit 18 of the above. ..

Further, Patent Document 2 processes a signal output from a partial discharge sensor for the purpose of providing an abnormality diagnosis device for a power cable that automatically detects the occurrence of an abnormality at a connection portion of the power cable after installation. After processing by the part, it is given to the buffer memory. The data processing unit detects an abnormality in the insulation part of the cable by increasing the peak value of the partial discharge pulse near the zero cross of the applied voltage in the φ-q distribution (or φ-q-n distribution) of the partial discharge. Have been described.

JP-A-2007-232495 JP-A-5-80112

Even if the conventional system described above attempts to diagnose the insulation performance of the power cable based on the discharge signal generated in the gap (oil gap, void, etc.) inside the insulator of the power cable, the operating frequency of the measurement circuit is high. As long as the signal is not supported, it is difficult to accurately judge the quality of the insulation performance of the power cable from the measurement result of the partial discharge signal, no matter how good the diagnostic program is. Therefore, the present invention provides a computer system capable of accurately evaluating a power device based on the measured discharge signal even when the discharge signal emitted from the power device cannot be completely measured, and a method thereof. It is the purpose.

In order to achieve the above object, the present invention is a computer system for measuring a high frequency discharge signal from a power device to which AC power is applied and evaluating the power device based on the high frequency discharge signal, and is a sensor. The controller includes an electronic circuit that measures the high-frequency discharge signal output from, a controller that controls the electronic circuit, and a memory that records the high-frequency discharge signal measured by the electronic circuit. The electronic circuit is controlled so that the timing of measuring is adjusted based on the AC cycle, the high-frequency discharge signal measured by the electronic circuit is acquired from the memory, and the power device is subjected to the high-frequency discharge signal based on the high-frequency discharge signal. It is a computer system that reproduces the generated high-frequency discharge signal. The present invention is further a method for evaluating electric power equipment.

According to the present invention, it is possible to provide a computer system and a method capable of accurately evaluating a power device based on the measured discharge signal even when the discharge signal emitted from the power device cannot be completely measured. can.

It is a block diagram of the hardware which concerns on the example of the form which applied the computer system to the electric power cable. It is a block diagram which shows the hardware configuration example of a computer system. FIG. 5 is a waveform diagram showing a partial discharge signal generated at a poorly insulated part of a power cable and detected by a sensor in synchronization with commercial AC power (for one phase). It is a waveform figure which shows an example of the measurement operation of a computer system. It is a functional block diagram of the computer system of FIG. It is a flowchart which shows an example of the operation of a computer system. It is a flowchart which concerns on an example of the process which a computer system diagnoses a power cable. It is a flowchart explaining an example of the signal measurement operation of a computer system.

Hereinafter, embodiments of the computer system according to the present invention will be described with reference to the drawings. This computer system is for evaluating electric power equipment, and the evaluation includes diagnosing the quality of insulation performance of the electric power equipment. As power equipment, a power system (power transmission network, distribution network), a power transmission network for large-scale consumers such as factories, buildings, commercial facilities, stations, etc., and a power cable used for a power distribution network, etc. will be described as suitable examples. .. The computer system measures the high-frequency signal emitted from the power cable to diagnose the quality of the insulation performance of the power cable. The high-frequency signal may be a discharge signal generated in a gap portion (oil gap, void, etc.) inside the insulator of the power cable. Hereinafter, this signal is referred to as a partial discharge signal.

FIG. 1 is a block diagram of hardware according to an example of a form in which a computer system is applied to a power cable. Reference numeral 100 is a power cable. The power cable 100 may be an oil-immersed paper cable (Oil Field: OF) or a CV cable (crosslinked polyethylene: CV).

Reference numeral 101 is a sensor that detects a partial discharge signal. Since this sensor detects a partial discharge signal from the power cable, a plurality of sensors are present along the power cable at predetermined intervals, such as 101a and 101b. The sensor may be a high frequency CT (Current Transformer). The sampling frequency of high-frequency CT is several hundred MHz or more, and even a partial discharge signal can be sufficiently detected.

There is a computer system 102 for each of the plurality of sensors. 102a is a computer system connected to the sensor 101a, and 102b is a computer system connected to the sensor 101b. The computer system diagnoses the power cable based on the high frequency signal (partial discharge signal) output from the sensor.

The computer system 102 may be a personal computer, a field device in edge computing, a gateway in fog computing, a control controller, a PLC (Programmable Logical Controller), an IED (Intelligent Electronic device), a MU (Merging Unit), or the like. The computer system may be in a form applied to a protection relay.

Reference numeral 103 is a signal transmission cable output by the sensor 101 to the diagnostic device 102. Since the transmission target is a high-frequency signal, a coaxial cable may generally be used. Reference numeral 104 is storage. The storage stores the partial discharge signal measured by the computer system 102, the result of the diagnosis of the power cable, the information related to the power cable 100, and the like. Information related to the power cable includes attribute information such as the material of the power cable 100, the dimensions of each part, the parameters and weights of electrical characteristics, the cable length, the date of manufacture, and the date of laying, as well as the information of the power cable 100. Various information for operating the power cable such as energization voltage, tide flow rate, past operation record, power failure history, connection configuration on the power system, and connection relationship with other systems may be used.

Reference numeral 105 is a server. The server 105 integrates and manages a plurality of computer systems 102, and refers to the information recorded in the storage 104 to comprehensively determine the power cable. The server, for example, uses the diagnostic information of the plurality of computer systems 102 to determine the position of an oil gap or the like, and / or predicts the period until the dielectric breakdown of the power cable 100. The server may share information with a central power supply command center, a control center, a power supply station, a substation, and the like for comprehensive determination. A plurality of servers 105 may exist due to differences in processing contents, distribution of processing load, and the like. The same applies to the storage 104.

The network 106 connects to the computer system 102, the storage 104, and the server 105, and transmits information between them. Examples of implementation of the network 106 are IEEE 802.3, various industrial networks, IEC 61784, IEC 61158, IEC 61850 (including IEC 61850-90-3), IEC 62439, IEC 61850-7-420, IEC 60870-5. 104, DNP (Distributed Network Protocol) 3, IEC 6970, IEEE 802.1 AVB, CAN (Control Area Network: registered trademark), DeviceNet, RS-232C, RS-422, RS-485, ZigBe (Registered trademark), IEEE 802.15, IEEE 802.15, mobile communication, OpenADR, ECHONET Lite (registered trademark), OpenFlow (registered trademark) and the like may be used. The communication format between the computer system 102, the storage 104, and the server 105 follows the above protocol.

The communication protocol of the application layer may be web, HTTP (Hypertext Transfer Protocol), XML (Extension Markup Language), SOAP, RPC (Remote Procedure Call), or SQL.

The computer system 102 may exist without being connected to the network 106. In that case, the computer system 102 may have a storage function of storage inside. An example of implementing the data storage function of the storage 104 and the computer system 102 is a database, a file server, a storage device, a NAS (Network Attached Storage), a SAN (Storage Area Network), or a non-volatile storage medium or an external storage medium. good.

The non-volatile storage medium may be a hard disk drive (HDD), a solid state drive (SSD), or a flash memory. The external storage medium that can be easily removed may be a floppy disk (FD), a CD, a DVD, a Blu-ray (registered trademark), a USB memory, a compact flash (registered trademark), or the like. The computer system 102 may be provided with a dedicated connection interface for these storage media.

Next, a configuration example of the hardware of the computer system 102 is shown in FIG. The CPU 120 transfers the program from the non-volatile storage medium 125 to the memory 124 and executes the program. Examples of the execution program include an operating system (hereinafter referred to as an OS) and an application program running on the OS. The CPU 120 may be a multi-core CPU, a many-core CPU, or a CPU with a built-in FPGA.

The LAN 121 receives a transmission request and transmission data from software running on the CPU 120, transmits the transmission data to the network 106, and transmits the data received from the network 106 via the bus 126 to the CPU 120, the memory 124, and the non-volatile. Transfer to the sex storage medium 125. An example of mounting the LAN 121 may be an IC such as an FPGA, CPLD, ASIC, or gate array, or may be integrated with the CPU 120. The LAN 121 may be an IEEE 802.3 communication device including a MAC layer and a PHY (physical) layer, or may include a PHY function. The LAN 121 may be an IEEE 802.3 standard MAC (Media Access Control) chip, a PHY chip, or a composite chip of MAC and PHY. The LAN 121 may be included in the CPU 120 or a chipset that controls an information path inside the computer.

The data processing IC 122 measures the sensor data transferred from the ADC 123, and transmits the processing result to one or more of the CPU 120, the memory 124, the non-volatile storage medium 125, and the LAN 121 via the bus 126. Information may be set in the data processing IC 122 by access from the CPU 120, LAN 121, or the like. The information to be set is a parameter related to the measurement of circuit configuration information and sensor data as an IC (FPGA, CPLD, etc.).

Implementation examples of the data processing IC 122 are FPGAs, CPLDs, general-purpose ICs, dedicated ASICs, gate arrays, FPGAs with built-in processors, and software that operates on them. The circuit configuration information (configuration data) when the FPGA or CPLD is mounted is stored in the non-volatile storage medium 125 and may be read as needed. The non-volatile storage medium 125 for storing circuit configuration information may not be connected to the bus 126 and may be directly connected to the data processing IC 122 as a dedicated non-volatile storage medium.

The ADC 123 is an analog-to-digital converter that digitally converts an analog signal transmitted from the sensor 101 and transmits the analog signal to the data processing IC 122. A plurality of ADCs 123 may be provided, and the partial discharge signals may be measured by shifting their respective capture phases. In this way, even if the sampling frequency of the ADC 123 alone is low resolution, the high frequency partial discharge signal can be measured.

The memory 124 is a storage area for storing a program and temporarily storing data, and stores an OS, an application program, and the like transferred from the non-volatile storage medium 125. Examples of the memory 124 include static RAM, DRAM, NVRAM and the like.

The non-volatile storage medium 125 is an information storage medium, and is used for storing an OS, an application, a device driver, and the like, a program for operating the CPU 120, and data as a result of executing the program. Examples of the non-volatile storage medium 125 include a hard disk drive (HDD), a solid state drive (SSD), and a flash memory. Further, as an external storage medium that can be easily removed, the use of a floppy disk (FD), a CD, a DVD, a Blu-ray (registered trademark), a USB memory, a compact flash (registered trademark), or the like is exemplified.

The bus 126 connects the CPU 120, the LAN 121, the memory 124, and the non-volatile storage medium 125, respectively. Examples of the bus 126 include a PCI bus, an ISA bus, a PCI Express bus, an AMBA (registered trademark) bus, a system bus, a memory bus, and an on-chip bus.

Assuming that the sampling frequency of the data processing IC 122 and the ADC 123 is 200 MHz and the frequency of the partial discharge signal output from the sensor 101 is 500 MH, the computer system 102 cannot sufficiently measure the partial discharge signal, and as a result, the oil gap of the power cable The degree of defect cannot be diagnosed correctly. However, in the computer system 102, even if the data processing IC 122 has a low cost and its sampling frequency is inferior to the frequency of the partial discharge signal output from the sensor 101, the partial discharge generated in the power cable based on the measurement data The signal is reproduced so that the degree of deterioration of the insulation performance of the power cable can be accurately diagnosed. In addition, "reproduction" may be paraphrased as "estimation". Then, the computer system 102 may be understood as including the server 105 and / or the storage 104. A plurality of computer systems may be collectively understood as one computer system.

FIG. 3A is a waveform diagram showing a partial discharge signal generated at a poorly insulated portion of the power cable 100 and detected by the sensor 101 in synchronization with commercial AC power (for one phase). Reference numeral 1000 in FIG. 3A indicates AC power. -I is output in order every 2ns. The sensor 101 detects and outputs partial discharge signals a, b, c, ... I in each of a plurality of cycles (first cycle, second cycle, third cycle, ...).

On the other hand, assuming that the sampling frequency of the data processing IC 122 is 5 ns, the data processing IC 122 can measure only a part of the partial discharge signal per cycle of AC power. However, the computer system 102 superimposes a plurality of AC cycles, synthesizes the partial discharge signal measured by the data processing IC 122 while shifting the measurement start phase in each of the plurality of cycles, and actually generates the power cable. By reproducing the pattern of the high-frequency partial discharge signal in at least one cycle and evaluating it, the insulation state of the power cable can be accurately diagnosed. The computer system 102 may determine the AC cycle based on the applied voltage cycle (commercial AC power) of the power cable. Preferably, it may be the same cycle as the applied voltage cycle. A plurality of AC cycles are the minimum observation period, and one cycle belonging to the observation period is a unit period.

As shown in FIG. 3B, the CPU 120 determines the number of superimposed cycles to be “3” based on the sampling frequency of the data processing IC 122: 200 MHz and the frequency of the partial discharge signal: 500 MHz, and determines this as “3” in the data processing IC 122. Set. Further, the CPU 120 determines the shift amount of the measurement start phase to be 1 ns, and sets this in the data processing IC 122.

As the measurement cycle, the number of superimposed cycles may be determined by the frequency of the partial discharge signal and the operating frequency on the diagnostic device side (the operating frequency of each of the ADC 123 and the data processing IC 122, etc.). The data processing IC (FPGA) 122 can adjust the shift amount of the signal acquisition phase in ns units.

The data processing IC 122 measures a partial discharge signal every 5 ns, which is its own operating frequency, and the data processing IC 122 further shifts the measurement start phase by 1 ns from the starting point 1002 of the first cycle and outputs a partial discharge from the sensor. When the signal measurement is started, the partial discharge signals a, d, f, and i can be measured in the first cycle.

Then, when the data processing IC 122 continues the measurement of the partial discharge signal output from the sensor by further shifting the measurement start phase by 1 ns from the starting point 1004 of the second cycle, for a total of 2 ns, the partial discharge signal b , E, g, j can be measured. Further, when the data processing IC 122 continues the measurement of the partial discharge signal output from the sensor by further shifting the measurement start phase by 1 ns from the starting point 1006 of the third cycle, for a total of 3 ns, the partial discharge signal c , H can be measured.

The CPU 120 synthesizes the partial discharge signals measured in each of the first to third cycles in consideration of the phase difference of the partial discharge signals from the starting point of the cycle, thereby forming one cycle shown in FIG. 3A. The generated partial discharge signals a, b, ... I, j can be reproduced.

Next, a functional block diagram (FIG. 4) of the computer system 102 will be described. The "module" shown in FIG. 4 is realized by one or more elements shown in FIG. Modules may be understood as functions implemented by programs and / or hardware. Modules may be paraphrased as "means", "parts", or "elements".

The phase setting module 110 refers to the information in the storage area 115 to obtain the amount of the phase to be shifted (“1ns” in FIG. 3B) described above, and sets this in the measurement signal receiving module 113. The phase setting module 110 sets the start of the AC cycle, the time information of the AC cycle, the zero cross timing of the AC cycle, and the like in the measurement signal receiving module 113 based on the AC cycle of the voltage applied to the power cable 100.

The cycle number setting module 116 determines the number of superimposed cycles described above with reference to the information in the storage area 115, and sets this in the measurement signal receiving module 113. The storage area 115 may be configured in the non-volatile storage medium 125 and / or the storage 104. Further, the phase setting module 110 may be connected to the communication module 114 to determine the phase shift amount based on the control information from the outside. Further, the cycle number setting module 116 may also determine the number of superimposed cycles based on the control information from the outside by connecting to the communication module 114.

The measurement signal receiving module 113 measures the partial discharge signal output from the sensor 101 based on the set information. The measurement signal receiving module 113 includes a CPU, a microcomputer, a CPU, a specific hardware function module in an icrocomputer, an FPGA (Field Programmable Gate Array), a CPLD (Complex Programmable Logical Device), a dedicated IC, and an analog / digital conversion. It is realized by one or more circuits. The measurement signal receiving module 113 may incorporate the measured value after confirming that the measured signal has been measured correctly. This is because there is a possibility of an abnormality in the sensor 101 or the ADC 123 or a soft error in the FPGA used by the data processing IC 122.

The measurement signal receiving module 113 stores the measured signal in the storage area 115. The measurement signal receiving module 113 may store the captured partial discharge signal in the storage area 115 after determining whether or not the captured partial discharge signal should be stored in the storage area 115, or may perform a predetermined calculation on the measured partial discharge signal. The added result may be stored in the storage area 115.

The diagnosis module 112 refers to the storage area 115, determines an abnormality in the power cable 100 to be diagnosed based on the partial discharge signal captured by the measurement signal receiving module 113, and stores the determination result in the storage area 115. ..

The communication module 114 receives a command / setting packet to the computer system 102 and transmits a packet from the computer system 102 to the storage 104 and the server 105 via the network 106. The communication module 114 shapes the signal and communicates according to the protocol format of the network 106.

Since the communication module 114 causes the other computer system 102, the storage 104, and the server 105 to execute a predetermined process (for example, measurement data storage process to the other computer system 102) within a constant delay, the maximum communication delay is guaranteed. A real-time communication system may be provided.

The storage area 115 stores related information necessary for determining the phase shift amount in the phase setting module 110 and determining the number of superimposed cycles in the cycle number setting module 116. Related information includes the material of the power cable 100, the dimensions of each part of the power cable 100, the parameters and weight of the electrical characteristics of the power cable 100, the cable length of the power cable 100, the date of manufacture of the power cable 100, and the power. Attribute information of the power cable 100 such as the laying date of the cable 100, energization voltage, tide flow rate, past operation results, history of hydraulic pressure in oil-immersed paper cable, power failure history and connection configuration on the power system, with other systems Operation information of the power cable 100 such as the connection relationship of the power cable 100, the measured value (charge amount, phase) of the partial discharge signal, the history information of the partial discharge signal such as the past measured value of the partial discharge signal, the attribute elimination method (data) of the computer system 102. The processing IC 122, the operating frequency of the ADC, etc.), and one or more of the measurement attributes such as the number of superimposed cycles described above may be used. The CPU 120 may determine the phase shift amount based on the operating frequency of the data processing IC 122 and the number of superimposed cycles. The CPU 120 may predict the frequency of the partial discharge signal and the amount of electric charge from the attribute information and the operation information of the power cable. The CPU 120 may determine the number of superposed cycles based on the frequency of the partial discharge signal and the operating frequency of the data processing IC 122.

The time synchronization module 118 synchronizes the computer system 102 with one or more of the other computer systems 102, the storage 104, and the server 105 according to a predetermined time synchronization protocol. The time synchronization module 118 implements GPS, NTP, IEEE1588, IRIG-B, etc. as a method for synchronization. The time system to be synchronized may be a relative time when the system of FIG. 1 is closed and operated, or an absolute time when linked with an external system.

Each of the plurality of computer systems 102 is time-synchronized with each other by including the time synchronization module 118. The signals measured by each of the plurality of computer systems 102 are added with the time information at the time of measurement and stored in the storage 104.

The server 105 also manages information on which part of the power cable each of the plurality of computer systems targets, and refers to the determination result of each of the plurality of computer systems, and at the same time, which part of the power cable It is possible to identify whether a partial discharge is occurring at the location.

Next, an example of the operation of the computer system 102 will be described with reference to the flowchart of FIG. The computer system 102 executes the flowchart of FIG. 5 at predetermined time intervals (for example, every 10 minutes). Hereinafter, the flowchart of FIG. 5 will be described with reference to the block diagrams of FIGS. 2 and 4.

The CPU 120 waits for the start of partial discharge signal measurement (S001). During this time, the phase setting module 110 detects the starting point of the AC cycle, sets this as the starting point of the measurement of the partial discharge signal in the measurement signal receiving module 113, and further, the cycle number setting module 116 superimposes the cycle. The number (3 cycles in FIG. 3B) is set in the measurement signal receiving module 113. The period of a plurality of superimposed cycles is hereinafter abbreviated as "measurement cycle" for convenience. Further, the phase setting module 110 determines the amount of phase to be shifted (FIG. 3B “1ns”). The cycle setting module 116 records the number of cycles of the measurement cycle, and the phase setting module 110 records the amount of phase to be shifted in the storage area 115.

When the CPU 120 finishes the standby process (S001), it shifts to S002 and causes the measurement reception signal receiving module 113 to execute the measurement of the partial discharge signal. When the measurement signal receiving module 113 detects the partial discharge signal, it acquires the discharge charge amount of the partial discharge signal and the phase from the start point of the cycle (1002, 1004, 1006 in FIG. 3B) to the measurement of the partial discharge signal. This is cumulatively stored in the storage area 115.

The measurement signal receiving module 113 sets a predetermined time in the timer when the measurement of the partial discharge signal is started, and ends the measurement when the predetermined time elapses (S003). The predetermined time may be a time necessary and sufficient for the diagnostic module 112 to obtain the measurement data necessary for reproducing the partial discharge signal. For example, when evaluating one cycle of commercial power of 50 Hz (20 milliseconds) for 10 cycles, it is 200 milliseconds.

Next, a process in which the computer system 102 diagnoses the power cable 100 will be described. FIG. 6 is a flowchart of the flow chart. The CPU 120 starts this flowchart at predetermined time intervals (for example, every hour) to activate the diagnostic module 112. The diagnostic module 112 refers to the storage area 115 and determines the presence or absence of an unevaluated measurement signal (partial discharge signal) (S100). When the diagnostic module 112 denies this determination, that is, determines that there are no unevaluated measurement signals in the storage area 115, the flowchart ends. If the power cable is not partially discharged, or if the measurement signal is equal to or less than a predetermined value, the measurement signal is not recorded in the storage area 115, so that the diagnostic module 112 determines and denies S100.

When the diagnostic module 112 determines that there is an unevaluated measurement signal (S100: Y), it reproduces the partial discharge signal in the power cable based on the charge amount and phase of the measurement signal (S102: see FIG. 3B). .. The diagnostic module 112 may remove noise from the detected signal when reproducing the partial discharge. For noise removal, a method using a signal processing technique such as a low-pass filter, a high-pass filter, a band-pass filter, a Fourier transform, or a wavelet transform is exemplified.

Next, the diagnostic module 112 calculates an index value for diagnosing the quality of the insulation performance of the power cable from the characteristics of the reproduced partial discharge signal (S104). This index value is, for example, the maximum discharge charge amount of the measured value of the partial discharge signal, the initial appearance phase of the measurement signal, the frequency of the measurement signal, the total value of the discharge charge amount of the plurality of measurement signals, and the phase of the plurality of measurement signals. One or more of the minimum value, maximum value, average value, standard deviation, rate of change of discharge charge amount of a plurality of measurement signals, and maximum amplitude when the measurement signal is converted into a frequency spectrum may be used. ..

Next, the diagnostic module 112 compares the evaluation value with the threshold value (S106). The diagnostic module 112 determines that there is an abnormality in the power cable when the evaluation value has a specific relationship with the threshold value (S108). Specific relationships are, for example, when the evaluation value is greater than the threshold value, when the evaluation value is equal to the threshold value, when the evaluation value is smaller than the threshold value, when the evaluation value includes the threshold value, or. The evaluation value may not include the threshold value. The relationship between the evaluation value and the threshold value may depend on the determination method.

The diagnostic module 112 determines that the start phase of the partial discharge is earlier than the predetermined phase, the minimum charge amount of the partial discharge signal is lower than the predetermined threshold value, or the minimum value of the generation interval of the manifestation phase of the partial discharge signal. If is lower than a predetermined threshold value, it may be determined that there is an abnormality in the power cable. Furthermore, even if the diagnostic module 112 determines that there is an abnormality in the power cable when the state in which the partial discharge signal is intermittently generated changes to the state in which the partial discharge signal is continuously generated. good. The diagnostic module 112 may determine the degree of change in the index value based on the history of the index value, compare this with a predetermined threshold value, and evaluate the power cable.

The evaluation module 112 may combine a plurality of determination methods when evaluating the power cable. In that case, the diagnostic module 112 may compare the value obtained by adding the parameters of each of the plurality of determination methods (for example, the difference between the index value and the threshold value) by a linear sum as an integrated parameter with the threshold value. Alternatively, the diagnostic module may finally determine the abnormality of the power cable only when the power cable is determined to be abnormal in a predetermined number or more of the determination methods among the plurality of determination methods. The diagnostic module may execute a plurality of determination methods in parallel, or may execute a plurality of determination methods in order. The diagnostic module may execute a plurality of determination methods hierarchically. For example, the diagnostic module first makes a determination regarding the maximum value of the partial discharge charge. When the determination module determines that this method is abnormal, then an abnormality determination regarding the minimum value of the partial discharge charge amount is applied. The diagnostic module executes a determination method for the amplitude of the frequency spectrum when the maximum charge amount is not determined to be abnormal. In this way, the diagnostic module can sequentially improve the accuracy for diagnosis by executing the determination method hierarchically.

The diagnostic module not only reproduces the partial discharge of the power cable based on a plurality of consecutive cycles, but also reproduces the partial discharge by combining the cycles existing in the multiple measurement cycles. good.

When the diagnostic module 112 determines that the power cable is abnormal, it notifies the outside of the abnormality and ends the flowchart. The notification may be to notify the storage 104 and the server 105 of the abnormality via the network 106, or the diagnostic device 102 itself may turn on the LED or the like and output an alarm such as a warning sound. When the diagnostic module 112 determines that S106 has no specific relationship, it ends the flowchart.

Next, the signal measurement operation (FIG. 5: S002) of the measurement signal receiving module 113 will be described with reference to the flowchart (FIG. 7) based on the measurement example shown in FIG. 3B. The CPU 120 starts the signal measurement operation for the measurement signal receiving module 113 based on the measurement cycle and the phase shift amount. When the measurement signal receiving module 113 determines the starting point 1002 of the AC cycle 1000 (S200), the signal acquisition start phase is shifted by 1 ns (S202). As a result, during the period of the first cycle, the measurement signal receiving module 113 sequentially measures the partial discharge signals a, d, f, and i every 5 ns. The measurement signal receiving module 113 stores the charge amount and the phase of the measured partial discharge signal in the storage area 115 (S204).

Next, the measurement signal receiving module 113 returns to S200 when the measurement cycle includes the next cycle (S206: Y), and returns to S200 when the measurement cycle does not include the next cycle (S206: N). ) Shifts to S003 (FIG. 5).

According to FIG. 3B, the measurement / diagnosis module 112 positively determines S206 and returns to S200, and when it determines the start point 1004 of the cycle, it shifts the signal acquisition start phase by 2 ns. As a result, the measurement signal receiving module 113 can measure the partial discharge signal every 5 ns during the cycle, so that the partial discharge signal of b, e, g, and j can be measured. The measurement signal receiving module 113 stores the charge amount and the phase of the measured partial discharge signal in the storage area 115.

Next, the measurement / diagnosis module 112 positively determines S206 and returns to S200, and when it determines the start point 1004 of the cycle, it shifts the signal acquisition start phase by 3 ns. As a result, the measurement signal receiving module 113 can measure the partial discharge signal every 5 ns during the cycle, so that the partial discharge signals of c and h can be measured. The measurement signal receiving module 113 stores the charge amount and the phase of the measured partial discharge signal in the storage area 115.

Subsequently, since the number of measurement cycle cycles of the measurement diagnosis module 112 is “3” and there is no next cycle, the measurement diagnosis module 112 negatively determines S206 and returns to S003 (FIG. 5).

を満足するものであればよい。 Assuming that the sampling frequency of the data processing IC 122 is "FIC" and the frequency of the partial discharge signal is "FPDM", the number C of the AC cycle constituting the measurement cycle is assumed to be "FIC".

Anything that satisfies the above.

“ＩＩＣ”はデータ処理ＩＣ１２２における１サンプリングの時間である（１ｓ／２００ＭＨｚ＝５ｎｓ）。サイクル数“Ｃ”を３とすると、“Ｔｓｈｉｆｔ”は１．６７になる。しかしながら、シフトできる位相の量は、データ処理ＩＣ１２２における最小調整可能単位時間（例えば、“１ｎｓ”）に依存するため、実際にシフトされる位相の量は“１ｎｓ”、又は、“２ｎｓ”であればよい。シフトできる位相の量は、最小調整可能単位時間によって制限されるため、サイクル数“Ｃ”は大きいほどよい。サイクル数が大きくなると、計測信号受信モジュール１１３は、その分多くの部分放電信号を取り込めるため、１サイクルの部分放電信号を再現する際の分解能を向上させることができる。 Then, the amount of the phase "Tshift" shifted for each cycle is set as follows.

“IIC” is the time for one sampling in the data processing IC 122 (1s / 200MHz = 5ns). Assuming that the number of cycles "C" is 3, "Tshift" is 1.67. However, since the amount of phase that can be shifted depends on the minimum adjustable unit time (for example, "1ns") in the data processing IC 122, the amount of phase that is actually shifted may be "1ns" or "2ns". Just do it. Since the amount of phase that can be shifted is limited by the minimum adjustable unit time, the larger the number of cycles "C", the better. As the number of cycles increases, the measurement signal receiving module 113 can take in a larger number of partial discharge signals, so that the resolution when reproducing the partial discharge signal of one cycle can be improved.

The upper limit of the number of cycles may be determined according to, for example, the shape of the insulator and / or the period during which the output of the partial discharge signal can be regarded as constant. Based on the resolution of the ADC 123, it can be considered that there is no change in the partial discharge state (generation mode of a plurality of partial discharge signals) of the power cable 100 during "100 ms", because one cycle is "20 ms". , "5" cycles (100ms / 20ms) is the upper limit of the number of cycles. The number of cycles setting module 116 may determine the number of cycles of the measurement cycle with the number of cycles determined by Equation 1 as the lower limit and the number of cycles of the measurement cycle may be changed from the upper limit of the number of cycles.

To demonstrate a period in which an AC voltage is applied to a power cable having the same material, length, and structure as the power cable 100 to be measured, imitating an oil gap, and it can be considered that there is no change in partial discharge. Therefore, a period in which there is no change in the generation mode of the plurality of partial discharge signals may be obtained. Alternatively, the evaluation values for each cycle may be compared, and the period in which there is no change in comparison with the predetermined threshold value may be set as the period in which the partial discharge state does not change. The measurement signal receiving module 113 may change the number of cycles based on a request from the server 105 and / or the system administrator via the network 106.

When the number of cycles constituting the measurement cycle increases, the diagnostic module 112 can increase the resolution when reproducing the partial discharge signal generated in the power cable from the partial discharge signal measured during the measurement cycle, resulting in an abnormality. Although the accuracy of the determination can be improved, the probability that the partial discharge signal fluctuates during a large number of cycles increases, and the reciprocity that reduces the accuracy of reproduction is affected by that amount. Therefore, as described above, the number of cycles may be limited below the upper limit of the number of cycles so that the accuracy of reproduction does not deteriorate even within the range in which the partial discharge signal does not fluctuate.

In the above description, the phase setting module 110 shifts the measurement start phase every one cycle of the AC cycle, but the measurement start phase may be shifted every plurality of cycles. In the above description, the diagnostic module 112 reproduces the partial discharge of the power cable based on the partial discharge signals measured in a plurality of consecutive cycles, but reproduces the partial discharge by combining several non-continuous cycles. May be good. For example, the diagnostic module 112 may reproduce the partial discharge signal by combining the measurement signals of several cycles excluding the cycle in which an inappropriate signal such as a noise signal or an outlier is added.

The diagnostic module 112 may determine the noise signal and outliers using a statistical method such as clustering classification. The diagnostic module 112 may obtain the frequency spectrum and remove the high frequency band or harmonic signal from the measurement signal. The diagnostic module 112 may perform this removal based on the results of operations (statistical methods or frequency spectra) for other cycles. For example, when a signal in a specific frequency band is measured in a certain cycle, the diagnostic module 112 may use this as noise, remove it by filtering in another cycle, and remove it by inverse Fourier transform. Further, if the diagnostic module 112 can determine or estimate the frequency of a noise signal such as a harmonic from the physical characteristics of the measurement result, the measurement signal in this frequency band may be filtered.

In the above description, the phase setting module 110 shifts the phase regardless of the characteristics of the measured partial discharge signal, but when the degree of change in the partial discharge exceeds a predetermined threshold value. Etc. may be used to shift the phase.

In the above description, the phase setting module 110 has set the phase shift amount to a constant value, but the shift amount is changed according to the change in the characteristics of the partial discharge signal, the change in the noise appearance cycle, and the like. You may change it. The phase setting module 110 may randomly change the phase shift amount according to the cycle. The phase setting module 110 may limit the randomly changing phase shift amount to a lower limit value and / or an upper limit value. The phase setting module 110 may evaluate a randomly set phase shift amount after measuring the partial discharge signal, and determine the phase shift amount based on the partial discharge signal. This evaluation may be performed according to the number of times the randomly set phase shift amount is diagnosed as an abnormality of the power cable, the frequency thereof, the number of times it is determined that the measurement data needs to be stored, the frequency thereof, and the like. When the phase setting module 110 determines by the evaluation that the phase shift amount is not appropriate, the phase shift amount may be randomly set again.

When the computer system 102 starts measuring the partial discharge signal, the phase setting module 116 is set to have a phase shift amount less than the value of Equation 2, and the cycle number setting module 116 is made to set the number of cycles to be larger than the value of Equation 1. , The sampling resolution for measuring the partial discharge signal is increased so that the measurement of the partial discharge signal is not missed when the measurement is started. After that, when the measurement signal receiving module 113 does not measure the partial discharge signal, for example, after the measurement is started, the computer system 102 increases the phase shift amount, reduces the number of measurement cycle cycles, and lowers the sampling resolution. good. In this way, the computer system may change the phase shift amount and the number of cycles of the measurement cycle according to the progress of the measurement of the partial discharge signal. Furthermore, the computer system 102 may dynamically determine the phase shift amount, for example, change, adjust, control, or set the phase shift amount based on the characteristics of the reproduced partial discharge signal. ..

The measurement signal receiving module 113 evaluates the measured partial discharge signal, for example, whether or not the charge amount of the partial discharge signal is equal to or higher than a predetermined value, and whether or not there is an influence of noise, and the partial discharge signal is evaluated. May be determined whether or not to store in the storage area 115. The measurement signal receiving module 113 may determine whether or not to store the measured signal based on the storable capacity or the storable throughput.

The server 105 can devise a predetermined countermeasure based on the abnormality of the power cable 100 determined by the computer system 102. For example, the server 105 operates the system so as not to flow the tidal current to the power cable determined to be abnormal, estimates the period until dielectric breakdown, plans a periodic inspection within that period, and / or the power cable. Replacement, maintenance, etc. are recommended.

The server 105 can determine the period until dielectric breakdown based on the result of the verification test conducted in advance, or may estimate it based on the past historical information. The server 105 can also apply machine learning and statistical methods to this estimation. In the empirical evaluation, the power cable may be charged until the dielectric breakdown, or the power supply may be stopped before the dielectric breakdown occurs, and the state inside the disassembled power cable may be visually checked or image processing may be applied to the dielectric breakdown. You may want to check for the presence or absence.

The server 105 may evaluate the position of the oil gap based on the characteristics of the amount of discharge charge measured by a single computer system 102. The server 105 can predict the position of the oil gap by machine learning on the actual data, or estimate the absolute value of the discharge charge amount and the amount of attenuation due to the resistance component of the power cable to evaluate the position of the oil gap. You can also do it. The server 105 may present a proposal for a new installation location or a change location of the computer system based on the diagnosis results of one or more computer systems 102. For example, if the two computer systems 102 measure the partial discharge signal, but the server 105 cannot accurately assess the position of the oil gap due to the weak discharge charge, a new one is placed between the positions of the two computer systems. A request to set up the computer system 102 may be presented. A computer system that does not measure partial discharge may be relocated to this presented position.

The server 105 outputs measurement data to the computer system 102 and / or the storage 104 based on the operation information of the power cable from the central power supply command center, the control center, and the system facility with the power cable such as the substation. You may request it. For example, in the server 105, changes in the tidal current in the power cable 100 (increase, decrease, reverse power flow of the tidal current) and comparison with a predetermined threshold value (increased tidal current, exceeding the predetermined threshold value, etc.) occur. You may instruct to output the measurement data of the time and the predetermined period before and after the time.

Further, the server 105 may be instructed to output measurement data for a predetermined period before and after the abnormality or change in the hydraulic system of the OF cable and the date and time when the oil gas analysis is performed. Furthermore, the server 105 may be instructed to output measurement data for a predetermined period before and after the event of opening / closing operation to the circuit breaker and disconnector. It is important to observe the measurement data associated with the opening / closing operation because the opening / closing surge caused by the opening / closing operation can also trigger a partial discharge.

Furthermore, the server 105 may output measurement data based on the time of occurrence of a meteorological event such as a lightning strike. For example, when a lightning strike occurs near the power cable to be observed, the server may be instructed to acquire the lightning strike time and output measurement data for a predetermined period before and after that time. Based on the computer system 102 and / or the storage 104, the server 105 can execute the power cable diagnosis of the power cable in the same manner as the computer system 102. Instead of causing the computer system 102 and / or the storage 104 to output the target data, the server 105 may cause the computer system 102 to perform a diagnosis based on the target data and acquire the result.

The server 105 analyzes the information of the power grid, machine learning, etc. based on the diagnosis result of the power cable performed by the computer system 102, estimates the period until the dielectric breakdown of the power cable, and determines the period until the dielectric breakdown of the power cable. Can manage assets. The server 105 may determine the priority for renewing the power cable based on the number of days until dielectric breakdown of the power cable, the importance of the power cable, and the cost / budget for renewal. When determining the priority, the server 105 calculates the influence of external events (system operation, operation, weather, etc.) that may affect the partial discharge. The server 105, for example, raises the priority of the power cable in the area where the probability of lightning strikes is high, raises the priority of the power cable connected to the substation that can be opened and closed, or the power cable is dielectrically broken down. The priority may be determined according to the degree of influence (range of power failure, number of branches of connected power cable, etc.). The installation position of the computer system 102 with respect to the power cable may be changed periodically or based on the maintenance result of the power cable.

When the computer system 102 determines the abnormality of the power cable, the computer system 102 may instruct the nearby computer system 102 to record or output the measurement data at the time when the abnormality is determined. On the other hand, the computer system 102 may record the measurement data by a command other than the diagnosis computer system such as a server. As a result, even if the position where the oil gap may occur in the power cable is farther than the computer system 102 in which the abnormality is determined, the computer system 102 at the position where the oil gap may occur can record the measurement data. .. In order for the computer system 102 to command another computer system 102 to record and output measurement data, the network 106 may be provided with a real-time communication method. The computer system 102 may be able to store the capacity according to the worst guaranteed delay in the real-time communication method.

The CPU 102 may constantly repeat the flowchart of FIG. 5, and terminate the flowchart when the storage capacity of the measurement data reaches a predetermined condition at a specific date and time. The electric power device to which the present invention can be applied is not limited to the electric power cable. It may be a power device such as a circuit breaker, a transformer, or a disconnector that can generate a partial discharge.

100 ... Power cable, 101 ... Sensor, 102 ... Computer system, 103 ... Coaxial cable, 104 ... Storage, 105 ... Server, 106 ... Network, 110 ... Phase claim module, 112 ... Diagnostic module, 113 ... Measurement signal receiving module, 114 ... Communication module, 115 ... Storage area, 118 ... Time synchronization module, 120 ... CPU, 121 ... LAN, 122 ... Data processing IC, 123 ... ADC, 124 ... Memory, 125 ... Non-volatile storage medium, 126 ... Bus

Claims (11)

A computer system for measuring a high-frequency discharge signal from a power device to which AC power is applied and evaluating the power device based on the high-frequency discharge signal.
An electronic circuit that measures the high-frequency discharge signal output from the sensor,
A controller that controls the electronic circuit and
A memory that records the high-frequency discharge signal measured by the electronic circuit, and
With
The controller
The electronic circuit is controlled so that the timing of measuring the high-frequency discharge signal is adjusted based on the AC cycle.
The high frequency discharge signal measured by the electronic circuit is acquired from the memory, and the high frequency discharge signal is acquired.
Based on the high-frequency discharge signal, the high-frequency discharge signal generated in the power device is reproduced.

Adjusting the timing at which the electronic circuit measures the high-frequency discharge signal
The controller sets a plurality of cycles of the AC cycle, and
When the electronic circuit measures the high-frequency discharge signal over the plurality of cycles,
In each of the plurality of cycles, the electronic circuit shifts the phase at which the measurement of the high-frequency discharge signal is started from the starting point of the cycle.
Including

Further, the controller sets the number of cycles of the plurality of cycles to be equal to or higher than a value obtained by dividing the frequency of the high-frequency discharge signal by the sampling frequency of the electronic circuit.
Computer system. The controller sets the phase shift amount based on a value obtained by dividing the sampling frequency of the electronic circuit by the number of cycles of the plurality of cycles.
The computer system according to claim 1. A computer system for measuring a high-frequency discharge signal from a power device to which AC power is applied and evaluating the power device based on the high-frequency discharge signal.
An electronic circuit that measures the high-frequency discharge signal output from the sensor,
A controller that controls the electronic circuit and
A memory that records the high-frequency discharge signal measured by the electronic circuit, and
With
The controller
The electronic circuit is controlled so that the timing of measuring the high-frequency discharge signal is adjusted based on the AC cycle.
The high frequency discharge signal measured by the electronic circuit is acquired from the memory, and the high frequency discharge signal is acquired.
Based on the high-frequency discharge signal, the high-frequency discharge signal generated in the power device is reproduced.

Adjusting the timing at which the electronic circuit measures the high-frequency discharge signal
The controller sets a plurality of cycles of the AC cycle, and
When the electronic circuit measures the high-frequency discharge signal over the plurality of cycles,
In each of the plurality of cycles, the electronic circuit shifts the phase at which the measurement of the high-frequency discharge signal is started from the starting point of the cycle.
Including

Further, the controller
The phase shift amount is set to be large for each of the plurality of cycles.
Computer system. The controller
The amount of the phase shift is randomly increased for each of the plurality of cycles.
The computer system according to claim 3. The power device is a power cable
The high frequency discharge signal is generated by applying the AC power to a partial gap of an insulator of the power cable.
The computer system according to any one of claims 1 to 4. Since the sampling frequency of the electronic circuit is smaller than the frequency of the high frequency discharge signal output from the sensor, the electronic circuit measures a part of all the signals output from the sensor.
The computer system according to any one of claims 1 to 4. The controller sets the AC power cycle in the electronic circuit as the AC cycle.
The computer system according to any one of claims 1 to 4. Adjusting the timing at which the electronic circuit measures the high-frequency discharge signal based on the AC cycle
The controller sets a plurality of cycles of the AC cycle, and
Adjusting the timing at which the electronic circuit measures the high-frequency discharge signal over the plurality of cycles, and
including,
The computer system according to any one of claims 1 to 4. Adjusting the timing at which the electronic circuit measures the high-frequency discharge signal includes shifting the phase at which the measurement of the high-frequency discharge signal is started based on the AC cycle.
The computer system according to any one of claims 1 to 4. The controller
Based on the reproduced high-frequency discharge signal, the quality of the insulation performance of the power cable is diagnosed.
Output diagnostic results,
The computer system according to any one of claims 1 to 4. The amount of charge of each of the plurality of high-frequency discharge signals measured during the plurality of cycles,
The phase in which the high-frequency discharge signal was measured with respect to the starting point of the cycle in which the high-frequency discharge signal was measured, and
On the basis of,
Wherein the controller reproduces the high frequency discharge signal produced in the power equipment by the AC power,
The computer system according to any one of claims 1 to 4.

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