CN113866574B - Ring main unit fault detection system - Google Patents
Ring main unit fault detection system Download PDFInfo
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Abstract
The invention provides a fault detection system of a ring main unit, which comprises a partial discharge monitoring system, a temperature measurement system and a fault analysis system; the partial discharge monitoring system comprises a partial discharge monitoring device and a partial discharge information collecting device, the temperature measuring system comprises a temperature sensor and a temperature collecting device, the partial discharge monitoring device is connected with the partial discharge information collecting device, the temperature sensor is connected with the temperature collecting device, and the partial discharge information collecting device and the temperature collecting device are respectively in communication connection with the fault analysis system. The invention has the advantages that: 1) the invention has the functions of detecting partial discharge and temperature of the ring main unit and can adopt a fault comprehensive evaluation method to diagnose faults of the ring main unit; 2) the invention can monitor the ring main unit on line, monitor the running state of the ring main unit in real time, find potential fault defects and ensure the normal running of electrical equipment.
Description
Technical Field
The invention relates to a ring main unit fault detection system, and belongs to the technical field of power equipment on-line monitoring and fault diagnosis.
Background
In recent years, the construction of urban power grid cables is continuously promoted, a large number of overhead lines are eliminated, the cables are transformed into underground cables, power transmission corridors are saved, and urban appearances are beautified; meanwhile, the usage amount of the ring main unit used in cooperation with the cable is increased continuously, the cabin door must be closed to ensure safety when the ring main unit is in live operation, the operation states of components such as an internal switch, a bus, the cable, a cable connector and the like in the ring main unit cannot be directly observed and detected from the outside of the ring main unit basically, so that inspection personnel cannot visually inspect and maintain the ring main unit, and the number of the ring main units is large, so that great difficulty is brought to corresponding operation and maintenance work; due to the fact that operation and maintenance inspection is not timely or potential faults are not really detected, in recent years, faults of multiple ring main units occur in power grids of provinces and cities in the country, power failure events are caused, inconvenience is brought to normal electricity utilization of residential users, and unnecessary loss is caused. In the faults of the ring main unit, the faults caused by degradation and ablation of a cable terminal connector of the ring main unit are more, and the ring main unit is worthy of further research and a solution is provided in a targeted mode.
The looped netowrk cabinet space is little, and dehumidification heat dissipation condition is poor, has leaded to following problem: the joint is loosened due to expansion with heat and contraction with cold inside the joint, abnormal heating occurs, and the deterioration of the terminal insulating layer is aggravated; the cable terminal connector generates heat and loosens under the action of long-term thermal aging and mechanical aging due to the primary defects of contact resistance, bending stress and the like generated in production and installation, so that potential safety hazards are formed.
The main technical means for detecting the fault of the cable terminal connector of the ring main unit at present is to detect the partial discharge phenomenon of the ring main unit outside the ring main unit, and a handheld partial discharge tester is generally adopted for detection; for cost reasons, a handheld partial discharge tester is usually adopted to periodically detect the ring main unit, and the detection period is generally 1-2 times per year; after the ring main unit generates partial discharge, the detection frequency is increased according to the severity of the partial discharge phenomenon, but the real-time online continuous monitoring can not be realized due to the participation of detection personnel.
Disclosure of Invention
The invention provides a fault detection system for a ring main unit, and aims to solve the problem that the fault of a cable terminal connector of the ring main unit cannot be detected in real time in the prior art.
The technical solution of the invention is as follows: a fault detection system of a ring main unit comprises a partial discharge monitoring system, a temperature measuring system and a fault analysis system; the partial discharge monitoring system comprises a partial discharge monitoring device and a partial discharge information collecting device, the temperature measuring system comprises a temperature sensor and a temperature collecting device, the partial discharge monitoring device is connected with the partial discharge information collecting device, the temperature sensor is connected with the temperature collecting device, and the partial discharge information collecting device and the temperature collecting device are in communication connection with the fault analysis system respectively.
Furthermore, the fault analysis system comprises a communication module, a data processing module and a data analysis module, wherein the partial discharge information collecting device and the temperature acquisition device are respectively in communication connection with the communication module in the fault analysis system; the communication module is communicated with the partial discharge monitoring system and the temperature measuring system to acquire partial discharge monitoring data and temperature measuring data of the ring main unit, the data processing module is used for cleaning and formatting the acquired partial discharge and temperature measuring data to form an available data structure in the system, and the data analysis module is used for carrying out real-time data analysis and alarm on the partial discharge and temperature data.
Further, the data processing module performs data cleaning and formatting on the collected partial discharge and temperature measurement data: the method specifically comprises the following steps:
1. acquiring partial discharge data sequences within the last two minutes, wherein the number of partial discharge data in the partial discharge data sequences is not less than 3; if the number of the partial discharge data in the partial discharge data sequence is less than 3, repeating the step to obtain the partial discharge data sequence after waiting for two minutes, recording the obtained partial discharge data sequence as a number sequence PDrt, and simultaneously obtaining a temperature sequence in a corresponding time period as TMPrt;
2. starting from the first data of a sequence PDrt, if the numerical value is lower than a preset background value, replacing the current data with the data of the previous point, and if the first data is lower than the preset background value, replacing the first data with 0;
3. starting from the second data of the PDrt sequence, if the change rate of the current data is lower than 10% of that of the previous data, the previous data is considered as valid data;
4. traversing data according to the previous step, and completing one-time data screening after continuously finding 3 effective data, wherein the 3 effective data are an effective data group;
5. after an effective data group is obtained, calculating the average value of 3 effective data as an effective partial discharge value of the group, wherein the effective partial discharge value is called PDn, and n is increased from 0;
6. after traversing and calculating all data of the PDrt in the array, obtaining partial discharge effective values such as PD0 and PD1 …, taking the maximum value of all partial discharge effective values, recording the maximum value as PDmax, taking the PDmax as the maximum value of the PDrt in the array, and taking the PDmax as the maximum value of partial discharge in a corresponding time period;
7. the average value of TMPrt is obtained, i.e. the sum of all values is divided by the number of data, and the average value is designated as TMPmax.
Further, the data change rate is calculated as follows:
|An-An-1|÷An；
Anas current data, An-1Is the previous data.
Further, the data analysis module performs real-time data analysis and alarm on the partial discharge and temperature data, and specifically includes: the data analysis module obtains the latest PDmax and compares the latest PDmax with an alarm threshold, and when the PDmax continuously exceeds the alarm threshold and a set time continuously passes, a pre-alarm signal is started to trigger an alarm delay timer; in the timing process of the alarm delay timer, if the latest PDmax is lower than the alarm threshold value, clearing the pre-alarm signal and stopping the alarm delay timer; and if the alarm delay timer is full, sending out a real-time alarm signal.
Further, the data analysis module performs real-time data analysis and alarm on the partial discharge and temperature data, and specifically includes: recording a temperature data sequence [ T ] and a partial discharge data sequence [ PD ] in the first 24 hours, calculating the Pearson correlation after normalization, and obtaining a correlation coefficient k:
when the equipment stably runs, k is relatively stable, and when the change of k is relatively large (kmax-kmin is more than 0.5) in 24 hours, the partial discharge is considered to have an abnormal condition, and an alarm signal is sent out.
Furthermore, the partial discharge monitoring devices and the temperature sensors are all provided with a plurality of partial discharge monitoring devices and temperature sensors.
Furthermore, the partial discharge monitoring device comprises a CPU, an analog-to-digital converter (AD), a signal conditioning circuit and a signal input interface; when the device works, a high-frequency partial discharge signal is collected from a partial discharge signal sensor arranged in the ring main unit through a signal input interface, then signal amplification and signal detection processing are carried out through a signal conditioning circuit to form a conditioning signal, and finally a CPU controls an analog-to-digital converter to carry out high-speed sampling and data calculation on the conditioning signal to generate a partial discharge maximum value and a PRPD spectrogram so as to complete the collection and monitoring of the partial discharge signal of the ring main unit.
Furthermore, the signal conditioning circuit comprises a signal amplification part and a signal detection part, an integrated radio frequency low noise amplifier or an operational amplifier is adopted to build an amplification circuit to realize amplification of an original partial discharge signal, the original signal is processed through a peak detection or power detection device, and a detection signal of 1kHz-20kHz is output and then is sent to an AD sampling part for sampling.
Further, the partial discharge maximum value and the PRPD spectrogram are generated according to the following method: sampling the local discharge signal at a fixed sampling rate, wherein the sampling rate is not lower than 100 kSPS; setting PDM as a pulse partial discharge value, and giving an initial value of PDM as 0; collecting latest data PDnLast, last and previous time data PDn-1Making a comparison, e.g. PDn>PDn-1Let PDM = PDnSuch as PDn<PDn-1Then a PRPD pulse data set (TM) is obtainednPDM) for preservation, TMnPerforming next acquisition calculation for the current timestamp (namely, the current time is modulo 20ms and ranges from 0 to 19999 in the unit us), and simultaneously resetting the PDM; cumulatively (TM, PDM)n=0,1…, namely PRPD data; in the above calculation process, statistics is generally performed with 2s as one period, and PDM is takenn=0,1…The maximum value in (1) is taken as the current partial discharge maximum value.
Furthermore, the partial discharge information collecting device comprises a CPU, a wired communication interface and a wireless communication interface; the wired communication interface supports the access of the partial discharge monitoring device in a wired mode to transmit information, and the wireless communication interface accesses the partial discharge monitoring device in a wireless communication protocol to transmit information.
Furthermore, the temperature measuring system is a wireless temperature measuring system, the temperature sensor is fixedly mounted on a bus and/or a cable terminal joint of the ring main unit, the temperature sensor is a wireless temperature measuring sensor, and the temperature acquisition device is communicated with the temperature sensor through a wireless communication protocol to acquire data of each temperature sensor.
Furthermore, the temperature measuring system is a wireless temperature measuring system, and the temperature sensor is a passive wireless temperature sensor.
The invention has the advantages that:
1) the invention has the functions of detecting partial discharge and temperature of the ring main unit and can adopt a fault comprehensive evaluation method to diagnose faults of the ring main unit;
2) the invention can monitor the ring main unit on line, monitor the running state of the ring main unit in real time, find potential fault defects and ensure the normal running of electrical equipment.
Drawings
Fig. 1 is a schematic diagram of a fault detection system of a ring main unit according to the invention.
Fig. 2 is a schematic diagram of a partial discharge monitoring device for collecting partial discharge signals.
Fig. 3 is a schematic diagram of a method for data cleaning and formatting of the collected partial discharge and temperature measurement data by the data processing module.
Detailed Description
A fault detection system of a ring main unit comprises a partial discharge monitoring system, a temperature measuring system and a fault analysis system; the partial discharge monitoring system comprises a partial discharge monitoring device and a partial discharge information collecting device, the temperature measuring system comprises a temperature sensor and a temperature collecting device, the partial discharge monitoring device is connected with the partial discharge information collecting device, the temperature sensor is connected with the temperature collecting device, and the partial discharge information collecting device and the temperature collecting device are respectively in communication connection with the fault analysis system.
The fault analysis system comprises a communication module, a data processing module and a data analysis module, and the partial discharge information collecting device and the temperature acquisition device are respectively in communication connection with the communication module in the fault analysis system; the communication module is communicated with the partial discharge monitoring system and the temperature measuring system to acquire partial discharge monitoring data and temperature measuring data of the ring main unit, the data processing module is used for cleaning and formatting the acquired partial discharge and temperature measuring data to form an available data structure in the system, and the data analysis module is used for carrying out real-time data analysis and alarm on the partial discharge and temperature data.
The data processing module is used for carrying out data cleaning and formatting on the collected partial discharge and temperature measurement data: the method specifically comprises the following steps:
1. acquiring partial discharge data sequences within the last two minutes, wherein the number of partial discharge data in the partial discharge data sequences is not less than 3; if the number of the partial discharge data in the partial discharge data sequence is less than 3, repeating the step to obtain the partial discharge data sequence after waiting for two minutes, recording the obtained partial discharge data sequence as a number sequence PDrt, and simultaneously obtaining a temperature sequence in a corresponding time period as TMPrt;
2. starting from the first data of the PDrt sequence, if the numerical value is lower than a preset background value, replacing the current data with the data of the previous point, and if the first data is lower than the preset background value, replacing the first data with 0;
3. starting from the second data of the PDrt sequence, if the change rate of the current data is lower than 10% of that of the previous data, the previous data is considered as valid data;
4. traversing data according to the previous step, and finishing one-time data screening after continuously finding 3 effective data, wherein the 3 effective data are an effective data group;
5. after an effective data group is obtained, calculating the average value of 3 effective data as an effective partial discharge value of the group, wherein the effective partial discharge value is called PDn, and n is increased from 0;
6. after traversing and calculating all data of the PDrt in the array, obtaining partial discharge effective values such as PD0 and PD1 …, taking the maximum value of all partial discharge effective values such as PD0 and PD1 …, recording the maximum value as PDmax, and taking PDmax as the maximum value of the PDrt in the corresponding time period;
7. the average value of TMPrt is taken, i.e. the sum of all values is divided by the number of data, and the average value is denoted as TMPmax.
The data rate of change is calculated as follows:
|An-An-1|÷An；
Anas current data, An-1Is the previous data.
The data analysis module performs real-time data analysis and alarm on the partial discharge and temperature data, and specifically comprises the following steps: the data analysis module obtains the latest PDmax and compares the latest PDmax with an alarm threshold, and when the PDmax continuously exceeds the alarm threshold and a set time continuously passes, a pre-alarm signal is started to trigger an alarm delay timer; in the timing process of the alarm delay timer, if the latest PDmax is lower than the alarm threshold value, clearing the pre-alarm signal and stopping the alarm delay timer; and if the alarm delay timer is full, sending out a real-time alarm signal.
The data analysis module carries out real-time data analysis and alarm on the partial discharge and temperature data, and further specifically comprises the following steps: recording a temperature data sequence [ T ] and a partial discharge data sequence [ PD ] in the first 24 hours, calculating the Pearson correlation after normalization, and obtaining a correlation coefficient k:
when the equipment stably runs, k is relatively stable, and when the change of k is relatively large (kmax-kmin is greater than 0.5) in 24 hours, the partial discharge is considered to possibly have an abnormal condition, and an alarm signal is sent out.
The temperature measuring system is preferably a wireless temperature measuring system, and the temperature sensor is preferably a passive wireless temperature sensor.
The partial discharge monitoring device and the temperature sensor are both a plurality of.
The partial discharge monitoring device comprises a CPU, an analog-to-digital converter (AD), a signal conditioning circuit and a signal input interface; when the device works, a high-frequency partial discharge signal is collected from a partial discharge signal sensor arranged in the ring main unit through a signal input interface, then signal amplification and signal detection processing are carried out through a signal conditioning circuit to form a conditioning signal, and finally the conditioning signal is subjected to high-speed sampling and data calculation (including generation of a partial discharge maximum value, a PRPD spectrogram and the like) through a CPU (central processing unit) control analog-to-digital converter, so that the collection and monitoring of the partial discharge signal of the ring main unit are completed.
The signal conditioning circuit comprises a signal amplification part and a signal detection part, an original partial discharge signal is generally small and can be processed only after being amplified, an integrated radio frequency low noise amplifier or a high-bandwidth operational amplifier is adopted to build an amplification circuit to realize the signal conditioning, the frequency of the original partial discharge signal is high and generally ranges from 100kHz to 100MHz, the signal conditioning cannot be directly sampled by adopting high-speed AD in consideration of the device cost, the original signal is generally processed by a peak detection device or a power detection device, and the detection signal of 1kHz to 20kHz is output and then is sent to the AD sampling part for sampling.
The high-speed sampling and data calculation of the conditioning signals generate a partial discharge maximum value, a PRPD spectrogram and the like.
The partial discharge maximum value and the PRPD spectrogram (phase-resolved partial discharge spectrogram) are generated as follows: sampling the local discharge signal at a fixed sampling rate, wherein the sampling rate is not lower than 100 kSPS; setting PDM as a pulse partial discharge value, and giving an initial value of PDM as 0; collecting latest data PDnLast, last and last time data PDn-1Making a comparison, e.g. PDn>PDn-1Let PDM = PDnSuch as PDn<PDn-1Then, a PRPD pulse data set (TM) is obtainednPDM) for preservation, TMnPerforming next acquisition calculation for the current timestamp (namely, the current time is modulo 20ms and ranges from 0 to 19999 in the unit us), and simultaneously resetting the PDM; cumulative (TM, PDM)n=0,1…, namely PRPD data; in the above calculation process, statistics is generally performed with 2s as one period, and PDM is takenn=0,1…The maximum value in (1) is taken as the current partial discharge maximum value.
The partial discharge monitoring device further comprises a control circuit, wherein the control circuit comprises a power supply control circuit and a communication control circuit which support a low power consumption mode.
The partial discharge information collecting device comprises a CPU, a wired communication interface and a wireless communication interface; the wired communication interface can support the access of the partial discharge monitoring device in a wired mode to transmit information, and the wireless communication interface can access the partial discharge monitoring device in a wireless communication protocol to transmit information; the partial discharge information collecting device also comprises other control circuits which can support the operation of the CPU, the wired communication interface and the wireless communication interface.
The temperature measuring system is preferably a wireless temperature measuring system, the temperature sensor is fixedly arranged on a bus and/or a cable terminal joint of the ring main unit, and the temperature sensor is preferably a wireless temperature measuring sensor and further preferably a passive wireless temperature sensor; the temperature acquisition device is preferably in communication with the temperature sensors through a wireless communication protocol to acquire data of each temperature sensor.
Compared with the prior art, when the ring main unit fault analysis system works, the partial discharge information and the temperature information of the ring main unit are collected into the fault analysis system through the partial discharge information collecting device and the temperature collecting device, calculation analysis is carried out, and the operation state and the fault analysis result of the ring main unit are given; the partial discharge monitoring device collects signals of a partial discharge signal sensor arranged in the ring main unit and reduces the frequency of an original partial discharge signal by adopting a signal detection mode, so that the cost of the partial discharge sensor is obviously reduced, the requirements on the sampling rate of an AD device and the CPU main frequency are reduced, and the cost of the partial discharge monitoring device is greatly reduced; a passive wireless temperature measurement mode is adopted, so that the problem that the device in the ring main unit is inconvenient to communicate and supply power is solved; the fault analysis system has the functions of data cleaning and data analysis, can generate real-time alarm, and improves the accuracy of data and the accuracy of alarm due to the data cleaning.
Examples
The embodiments of the present invention will be further explained with reference to the drawings.
As shown in fig. 1, a ring main unit fault monitoring system includes an partial discharge monitoring system, a wireless temperature measuring system, and a fault analysis system.
The partial discharge monitoring system comprises a plurality of partial discharge monitoring devices and a partial discharge information collecting device.
As shown in fig. 2, the partial discharge monitoring device includes a signal input interface, a signal conditioning circuit, an AD sampling circuit, a CPU, a power control circuit, and a communication control circuit.
The signal input interface generally adopts a BNC interface or an SMA interface, and has good transmission effect and noise shielding effect on high-frequency partial discharge signals; the signal conditioning circuit comprises a signal amplification part and a signal detection part, an original partial discharge signal is generally small and can be processed after being amplified, an integrated radio frequency low noise amplifier or a high-bandwidth operational amplifier is adopted to build an amplification circuit to realize the signal conditioning, the frequency of the original partial discharge signal is high and generally ranges from 100kHz to 100MHz, the original partial discharge signal cannot be directly sampled by adopting high-speed AD in consideration of the device cost, the original signal is generally processed by a peak detection device or a power detection device, and the detection signal with the lower frequency is output and then sent to the AD sampling part for sampling.
The AD sampling part adopts a medium-high speed AD device, the maximum sampling frequency is 1MSPS, signals can be better collected, the condition that a CPU is overloaded and cannot process data in time is avoided, and meanwhile, the cost is lower.
The power control circuit comprises a power chip and a timing switch circuit, the ring main unit is inconvenient to walk, the device is powered by a battery, low-power consumption control must be achieved on a power supply, the power control circuit comprises an independently operating timer, after the device finishes signal acquisition and uploading, a CPU (central processing unit) actively closes the power chip, the device is thoroughly powered off, the timer is started simultaneously, when the timer finishes timing, the power chip is started by an output signal, and restarting of the system is completed.
The communication control circuit mainly comprises a wired communication control part and a wireless communication control part, so that the device has wired and wireless dual communication capability; the wired communication control is an RS485 controller, and RS485 communication is realized; the wireless communication control is an LORA controller, and LORA wireless communication is realized.
The partial discharge monitoring device collects high-frequency partial discharge signals from a partial discharge signal sensor arranged in the ring main unit, and for the ring main unit, a charged indicator is arranged when leaving a factory, and the charged indicator is connected with a line by using a high-voltage coupling capacitor and can sense whether the line is charged or not; the high-voltage coupling capacitor is about 40-100pF, and can well transmit high-frequency partial discharge signals, so that the partial discharge signals can be obtained from a nuclear phase hole of the charge indicator and sent to a signal input interface of the partial discharge monitoring device for detection.
The CPU of the partial discharge monitoring device controls AD to perform high-speed sampling and data calculation on the conditioning signals, generates data such as a partial discharge maximum value, a PRPD spectrogram and the like, and then uploads a calculation result to the partial discharge information collecting device through communication transmission.
As shown in fig. 1, the partial discharge information collecting device should have a wired communication interface, such as an RS485 interface, and a wireless communication interface, such as a LORA communication interface, so as to support the partial discharge monitoring device to access the partial discharge information collecting device in a wired or wireless manner.
As shown in fig. 1, the ring main unit wireless temperature measurement system includes a plurality of wireless temperature measurement sensors and a temperature acquisition device; the temperature sensor is suitable for the requirement that the ring main unit is small in space and inconvenient to run, generally adopts a passive wireless temperature sensor, and generally adopts induction power taking and LORA communication; the temperature sensor is generally fixedly mounted on a bus and a cable terminal joint of the ring main unit, communicates with the temperature acquisition device in an LORA wireless communication mode, and transmits the measured temperature to the temperature acquisition device.
As shown in fig. 1, the ring main unit fault analysis system includes a communication module, a data processing module and a data analysis module.
The communication module is provided with an RS485 interface and an LORA communication interface and has the functions of communication protocol analysis and data extraction; in the embodiment, the communication module directly comprises the local radio information collecting device function and the temperature collecting device function, so that the system structure is simplified and the implementation is convenient.
The data processing module acquires the partial discharge monitoring data and the temperature measurement data of the ring main unit from the communication module, and performs data cleaning and formatting on the acquired partial discharge and temperature measurement data to form an available monitoring data and data structure; in this embodiment, as shown in fig. 3, the method for the data processing module to perform data cleaning and formatting on the collected partial discharge and temperature measurement data is as follows: firstly, acquiring all partial discharge sampling data in the sampling time period; then screening all sampling values according to a preset background noise value, removing sampling data lower than the background noise, and filling the removed data position with the previous data; the abnormal value screening comprises two steps, firstly, starting from the second data of all the data, when the change rate of the data is lower than that of the previous data by 10 percent, considering the previous data as effective data, traversing all the data according to the method, and when the number of continuous effective data reaches 3, taking the 3 data as an effective data group; and finally, carrying out numerical value calculation, namely firstly carrying out average value calculation on each effective data group to serve as an effective value of the group, and then taking the maximum value of all the effective values as a partial discharge maximum value in the sampling time period.
The data rate of change is calculated as follows: current data-previous data/current data.
The data analysis module carries out comprehensive analysis on the partial discharge and temperature data, including real-time data analysis and alarm output.
The data analysis module obtains real-time data and compares the real-time data with an alarm threshold value, and when the real-time value continuously exceeds the alarm threshold value and a set time continuously passes, a pre-alarm signal is started to trigger an alarm delay timer; in the process, if the real-time number value is lower than the alarm threshold value, the pre-alarm signal is cleared, the alarm delay timer is stopped, and if the alarm delay timer is full, the real-time alarm signal is sent out.
The embodiment has the functions of detecting partial discharge, temperature and electric field of the ring main unit, and can perform fault diagnosis on the ring main unit by adopting a fault comprehensive evaluation method.
Claims (8)
1. A fault detection system of a ring main unit is characterized by comprising a partial discharge monitoring system, a temperature measuring system and a fault analysis system; the partial discharge monitoring system comprises a partial discharge monitoring device and a partial discharge information collecting device, the temperature measuring system comprises a temperature sensor and a temperature collecting device, the partial discharge monitoring device is connected with the partial discharge information collecting device, the temperature sensor is connected with the temperature collecting device, and the partial discharge information collecting device and the temperature collecting device are respectively in communication connection with the fault analysis system;
the fault analysis system comprises a communication module, a data processing module and a data analysis module, and the partial discharge information collecting device and the temperature acquisition device are respectively in communication connection with the communication module in the fault analysis system; the communication module is communicated with the partial discharge monitoring system and the temperature measuring system to acquire partial discharge monitoring data and temperature measuring data of the ring main unit, the data processing module is used for cleaning and formatting the acquired partial discharge and temperature measuring data to form an available data structure in the system, and the data analysis module is used for carrying out real-time data analysis and alarm on the partial discharge and temperature data;
the data processing module is used for carrying out data cleaning and formatting on the collected partial discharge and temperature measurement data: the method specifically comprises the following steps:
1. acquiring partial discharge data sequences within the last two minutes, wherein the number of partial discharge data in the partial discharge data sequences is not less than 3; if the number of the partial discharge data in the partial discharge data sequence is less than 3, repeating the step to obtain the partial discharge data sequence after waiting for two minutes, recording the obtained partial discharge data sequence as a number sequence PDrt, and simultaneously obtaining a temperature data sequence in a corresponding time period as TMPrt;
2. starting from the first data of the PDrt sequence, if the numerical value is lower than a preset background value, replacing the current data with the data of the previous point, and if the first data is lower than the preset background value, replacing the first data with 0;
3. starting from the second data of the PDrt sequence, if the change rate of the current data is lower than 10% of that of the previous data, the previous data is considered as valid data;
4. traversing data according to the previous step, and finishing one-time data screening after continuously finding 3 effective data, wherein the 3 effective data are an effective data group;
5. after an effective data group is obtained, calculating the average value of 3 effective data as an effective partial discharge value of the group, wherein the effective partial discharge value is called PDn, and n is increased from 0;
6. after traversing and calculating all data of the PDrt in the array, obtaining partial discharge effective values such as PD0 and PD1 …, taking the maximum value of all partial discharge effective values, recording the maximum value as PDmax, taking the PDmax as the maximum value of the PDrt in the array, and taking the PDmax as the maximum value of partial discharge in a corresponding time period;
7. the average value of TMPrt is obtained, i.e. the sum of all values is divided by the number of data, and the average value is designated as TMPmax.
2. The ring main unit fault detection system according to claim 1, wherein the data change rate is calculated as follows:
|An-An-1|÷An；
Anas current data, An-1Is the previous data.
3. The ring main unit fault detection system according to claim 1, wherein the data analysis module performs real-time data analysis and alarm on the partial discharge and temperature data, and specifically comprises: the data analysis module obtains the latest PDmax and compares the latest PDmax with an alarm threshold, and when the PDmax continuously exceeds the alarm threshold and continues to pass through a set time, a pre-alarm signal is started to trigger an alarm delay timer; in the timing process of the alarm delay timer, if the latest PDmax is lower than the alarm threshold, clearing the pre-alarm signal and stopping the alarm delay timer; and if the alarm delay timer is full, sending out a real-time alarm signal.
4. The ring main unit fault detection system according to claim 1, wherein the data analysis module performs real-time data analysis and alarm on the partial discharge and temperature data, and specifically comprises: recording a temperature data sequence [ T ] and a partial discharge data sequence [ PD ] in the first 24 hours, calculating the Pearson correlation after normalization, and obtaining a correlation coefficient k:
when the equipment stably runs, k is stable, and when k changes within 24 hours and kmax-kmin is larger than 0.5, the partial discharge is considered to have an abnormal condition, and an alarm signal is sent out.
5. The ring main unit fault detection system according to claim 1, wherein the partial discharge monitoring device includes a CPU, an analog-to-digital converter, a signal conditioning circuit, and a signal input interface; when the device works, a high-frequency partial discharge signal is collected from a partial discharge signal sensor arranged in the ring main unit through a signal input interface, then signal amplification and signal detection processing are carried out through a signal conditioning circuit to form a conditioning signal, and finally a CPU controls an analog-to-digital converter to carry out high-speed sampling and data calculation on the conditioning signal to generate a partial discharge maximum value and a PRPD spectrogram so as to complete the collection and monitoring of the partial discharge signal of the ring main unit.
6. The ring main unit fault detection system according to claim 5, wherein the signal conditioning circuit comprises a signal amplification part and a signal detection part, the amplification of an original partial discharge signal is realized by adopting an integrated radio frequency low noise amplifier or an operational amplifier to build an amplification circuit, the original signal is processed by a peak detection or power detection device, and a detection signal with a frequency of 1kHz-20kHz is output and then is sent to an AD sampling part for sampling.
7. The ring main unit fault detection system according to claim 5, wherein the partial discharge maximum value and the PRPD spectrogram are generated as follows: sampling the local discharge signal at a fixed sampling rate, wherein the sampling rate is not lower than 100 kSPS; setting PDM as a pulse partial discharge value, and giving an initial value of PDM as 0; collecting latest data PDnLast, last and last time data PDn-1Making a comparison, e.g. PDn>PDn-1Let PDM = PDnSuch as PDn<PDn-1Then, a PRPD pulse data set (TM) is obtainednPDM) for preservation, TMnFor the current time stamp, i.e. the current timePerforming modulus taking for 20ms, wherein the range is 0-19999, the unit is us, and simultaneously performing PDM zero clearing to perform next acquisition calculation; cumulative (TM, PDM)n=0,1…, namely PRPD data; in the above calculation process, statistics is generally performed with 2s as one period, and the PDM is takenn=0,1…The maximum value in (1) is taken as the current partial discharge maximum value.
8. The ring main unit fault detection system as claimed in claim 1, wherein the partial discharge information collecting device includes a CPU, a wired communication interface, a wireless communication interface; the wired communication interface supports the access of the partial discharge monitoring device in a wired mode to transmit information, and the wireless communication interface accesses the partial discharge monitoring device in a wireless communication protocol to transmit information; the temperature measurement system is a wireless temperature measurement system, the temperature sensor is fixedly arranged on a bus and/or a cable terminal joint of the ring main unit, the temperature sensor is a wireless temperature measurement sensor, and the temperature acquisition device is communicated with the temperature sensor through a wireless communication protocol to acquire data of each temperature sensor; the temperature measuring system is a wireless temperature measuring system, and the temperature sensor is a passive wireless temperature sensor; the partial discharge monitoring device and the temperature sensor are both a plurality of.
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