CN114236315B - Submarine cable running state monitoring device and monitoring method thereof - Google Patents
Submarine cable running state monitoring device and monitoring method thereof Download PDFInfo
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Abstract
A submarine cable running state monitoring method belongs to the submarine cable on-line monitoring field. Including submarine cable, its characterized in that: whether the submarine cable has transient faults or not is judged by detecting whether a submarine cable bus PT zero sequence voltage transient signal is generated or not, fault early warning is carried out on the submarine cable by monitoring and recording electromagnetic transient signals which are generated by the submarine cable and flow through a metal shielding layer, and fault point distances are indicated. The submarine cable fault positioning system monitors the running state of the submarine cable line on line in real time, performs fault transient process generated at the moment of submarine cable fault, achieves fault early warning and fault automatic positioning of the submarine cable, and marks the position of a fault point at a background map of the system.
Description
Technical Field
The invention belongs to the field of on-line submarine monitoring, and particularly relates to a submarine cable running state monitoring device and a submarine cable running state monitoring method.
Background
The submarine cable is an important component of a power grid for supplying power to the sea island, and because the submarine cable is distributed in different sea areas, the submarine power cable is inconvenient to safely operate, maintain and repair due to faults. And island power supply electric wire netting is mostly single power supply, and sea cable circuit is the trunk of circuit, all can cause the power failure of different degree when cable trouble because running environment is abominable, the trouble that the ship was anchored and is caused to take place, and trouble spot seek and repair difficulty, maintenance cycle is long, has seriously influenced island resident's normal production life and island economic development.
Aiming at the development of an on-line monitoring system of the submarine cable, the method becomes the urgent need for solving the problems of monitoring the running state of the submarine cable and diagnosing and positioning faults at present.
Various methods exist for online monitoring technology of power cables at home and abroad, such as a direct current superposition method, a direct current component method, a difference frequency method, a dielectric loss method, a partial discharge method and the like, and therefore some application experience is accumulated. The online monitoring of foreign cables has been carried out earlier, more often in japan. As early as the 80 s, many diagnostic techniques such as a direct current component method, a superimposed voltage method, and a dielectric loss method have been developed in japan by continuing research and development in this field. On-line operation cable monitor (OLCM-On Line Cable Monitor) was developed by the japanese sumitomo electric industries, inc. The instrument is divided into a fixed type grounding system and a portable type grounding system, and the main application conditions are that the voltage level is 33, 66 and 11 OkV. For a system with neutral points which are not grounded, grounded through arc suppression coils or grounded through grounding resistors, the adopted method is mainly a direct current superposition method. The on-line monitoring of XLPE cables in China has relatively late starting and relatively slow development. The nineties were also beginning to work in Shanghai cable research institute and have performed field trials. Whether the operation of the cable is safe or not has great influence on the power system and various factories and mines, and the electric power system and the various factories and mines are gradually paid attention to by the electric power operation departments.
At present, the national universities and universities of electric power, north China universities, western Ann universities and Chongqing universities are mainly used for carrying out research in different directions on the on-line monitoring technology of the power cable by expert scholars of the universities and the scientific research institutes, and the methods such as partial discharge monitoring, traveling wave ranging, harmonic component analysis, grounding wire current analysis and the like are mainly adopted, and the method is basically remained in research and experimental stages at present and is not popularized and applied in an electric power system. In the whole, online monitoring and research on cable insulation faults at home and abroad is not mature enough. For long-distance submarine cable lines, the current ultra-high-speed data acquisition chip is mature, the Beidou/GPS time keeping precision also reaches the practical standard, and the traveling wave ranging method is feasible from technical conditions of on-line monitoring and fault positioning.
At present, products aiming at on-line monitoring and fault positioning of the power cable at home and abroad are not industrially popularized, a company with a leading technology is a power overhaul company of Keima, the company is provided with a power cable operation monitoring center, monitoring data and maintenance information of cable operation are provided for users, and fault diagnosis and the like are also in the front of the technology. For reliable operation detection and fault location of submarine cables, products in the field are still blank in the world at present.
Disclosure of Invention
According to the defects in the prior art, the invention aims to provide an on-line early warning method for the transient fault of the submarine cable, and the on-line early warning is implemented for the transient fault before the cable is damaged, so that a power supply department can conveniently overhaul in advance or in a planned way, and the running state monitoring device and the monitoring method for the submarine cable are improved in power supply reliability.
The invention relates to a submarine cable running state monitoring device which is characterized by comprising a lower computer 39, a sensor 40 and an upper computer 41, wherein the sensor 40 and the upper computer 41 are in communication connection with the lower computer 39;
the sensor 40 is used for carrying out real-time online acquisition on transient current signals and power frequency current signals and carrying out real-time online acquisition on zero-sequence voltage signals;
the lower computer 39 is used for processing the signals acquired by the sensor 40 and uploading the acquired data to the upper computer 41;
the upper computer 41 is used for analyzing and processing the data uploaded by the lower computer 39;
the sensor 40 comprises a combined current sensor 12 and a voltage sensor 13, wherein the combined current sensor 12 is arranged on the submarine cable body, and the voltage sensor 13 is arranged on the secondary side of a submarine cable submarine-land connection point or a transformer substation PT;
the lower computer 39 comprises a main control unit 1, a current signal data acquisition unit 42, a voltage signal data acquisition unit 43, a timekeeping module 5, a 4G communication module 6, a 485/CAN bus communication unit 7, a network port communication unit 8 and a power supply unit 11, wherein the current signal data acquisition unit 42 comprises a high-frequency current signal data acquisition unit 2 and a power frequency current signal data acquisition unit 3, the high-speed current signal data acquisition unit 2 and the power frequency current signal data acquisition unit 3 are in communication connection with a current signal interface unit 9, the voltage signal data acquisition unit 43 comprises a power frequency voltage signal data acquisition unit 4, the power frequency voltage signal data acquisition unit 4 is in communication connection with a voltage signal interface unit 10, the current signal interface unit 9 is connected with a combined current sensor 12, and the voltage signal interface unit 10 is connected with a voltage sensor 13;
the upper computer 41 comprises a server 42, and analysis software for analyzing sea cable faults is deployed in the server 42;
preferably, the main control unit 1 comprises a CPU14 with the model of ZYNQ7010, a 32-bit arm9 processor is arranged in the main control unit, and the main control unit is composed of the CPU14, an FPGA (field programmable gate array) programmable logic array 16 and a DDR2 memory 15, so that the functions of controlling data acquisition and timekeeping and data processing and forwarding are realized;
preferably, the time keeping module 5 comprises two parts, namely a GPS/beidou time service module 17 and an optical fiber time service module 18, wherein one of the two is optionally configured in the CPU14, the GPS/beidou time service module 17 adopts a U-blox module with time service precision reaching 10ns, the GPS antenna acquires time information and then converts the time information into PPS second pulses, the PPS second pulses are output to the main control unit 1 for time service, the optical fiber time service module 18 adopts an ethernet chip of backshoff, and the time service information is acquired through an optical fiber and then converted into PPS second pulses, and the PPS second pulses are output to the main control unit 1 for time service;
preferably, the 4G communication module 6 and the main control unit 1 exchange data through a USB protocol, are connected with an antenna through an SMA antenna interface 19, and are provided with micro SIM card slots on the circuit; the 485/CAN bus communication unit 7 comprises a 485 signal conversion circuit 20 and a CAN bus conversion circuit 21, wherein the 485 signal conversion circuit 20 and the CAN bus conversion circuit 21 respectively exchange data with a 485 signal interface 22 and a CAN bus interface 23 and forward the data to the main control unit 1; the network port communication unit 8 is used for data interaction during network port connection, and consists of gigabit network ports, and interacts with the main control unit 1 through a PHY protocol;
preferably, the high-frequency current signal collecting unit 2 includes a high-frequency current signal collecting circuit 24 and a self-checking pulse circuit 25, the high-frequency current signal collecting circuit 24 is composed of an AMP signal processing circuit 26 and four high-speed a/D conversion chips, and amplifies the high-frequency current traveling wave signal; the self-checking pulse circuit 25 is controllably generated by the main control unit 1 and is used for sending a self-checking pulse signal to the self-checking coil 36 for self-checking; the power frequency current signal acquisition unit 3 is composed of a two-stage integrating circuit 27 and an A/D conversion chip 28, and is used for realizing 0-5000A power frequency current acquisition; the power frequency voltage signal acquisition unit 4 comprises an AMP signal conditioning circuit 29 and a four-way A/D conversion chip 30, and acquires PT secondary side opening triangular voltage;
preferably, the current signal interface unit 9 and the voltage signal interface unit 10 are respectively composed of a 6pin current aviation plug interface 31 and a 6pin phoenix socket voltage interface 32, and are respectively used for connecting the high-frequency combined current sensor 12 and the voltage sensor 13;
preferably, the power supply unit 11 adopts an ADI power management chip 33 to supply power, is compatible with a power management function, and can realize seamless switching between a power supply and a backup battery 34;
preferably, the voltage sensor 13 collects the triangular voltage of the PT secondary side opening and is connected with the 6pin Phoenix master socket voltage interface 32 through the 6pin plug 35; the combined current sensor 12 is an open-close type, two groups of current transformers and a group of self-checking coils 36 are arranged in the combined current sensor, the two groups of current transformers are a power frequency current transformer 37 and a high frequency current transformer 38, the high frequency current transformer 38 and the power frequency current transformer 37 respectively collect high frequency current signals and power frequency current signals, the high frequency current transformers and the power frequency current signals do not interfere with each other, the self-checking coils 36 receive self-checking pulses of the lower computer 39 and then perform self-checking on the high frequency current transformer 38, and the voltage sensor 13 is an electromagnetic voltage sensor.
The invention relates to a monitoring method of a submarine cable running state monitoring device, which is characterized by comprising the following steps of:
1. mounting sensor
Two ends of each submarine cable line are respectively provided with a set of lower computer 39 and a combined current sensor 12;
specifically, the combined current sensor 12 is arranged on the submarine cable body, and transient current signals and power frequency current signals are collected and recorded on line in real time;
the voltage sensor 13 is arranged on the sea cable sea land connection point or the PT secondary side of the transformer substation, and zero-sequence voltage signals are acquired and recorded on line in real time through the voltage sensor 13;
2. lower computer initialization
After the lower computer 39 is started, the power supply unit 11 supplies power to other units of the lower computer 39, and then the lower computer 39 enters an initialization stage, wherein the time keeping part is precisely time-controlled by the time keeping module 5 according to the fact that the optical fiber time-controlling module 18 or the GPS time-controlling/Beidou time-controlling module 17 is arranged in the main control unit 1; in addition, a 485/CAN bus communication unit 7, a 4G communication module 6 or a network port communication unit 8 is selected according to the internal arrangement of the main control unit 1 to upload the heartbeat of the equipment to the upper computer 41;
3. self-checking
When the initialization is completed, the lower computer 39 sends a pulse signal to the combined current sensor 12 for self-checking by the self-checking pulse circuit 25, and sends a self-checking result to the upper computer 41;
4. on-line monitoring
The lower computer 39 enters an on-line monitoring stage, and the power frequency voltage current and the transient current acquired by the combined current sensor 12 and the voltage sensor 13 are acquired in real time through the high-frequency current signal data acquisition unit 2, the power frequency current signal data acquisition unit 3 and the power frequency voltage signal data acquisition unit 4;
let i be set For the set threshold value, when a certain signal is collected to meet that i is more than or equal to i set When the waveform amplitude reaches more than a threshold value (realized by a comparator in an FPGA), forming a waveform file for high-frequency current, power frequency voltage current and timestamp information in a certain specific time period before and after the triggering time, storing the waveform file into the DDR2 memory 15, then sending the file to the upper computer 41 by the lower computer 39, analyzing and processing the waveform file sent by the lower computer 39 after the upper computer 41 receives the waveform file, judging that a submarine cable fails when the triggering condition is met, and determining the fault alarm level, wherein the method comprises the following two steps: only a transient fault event is generated at the moment of triggering, but the power frequency voltage and current waveform does not prompt the generation of a fault, and then fault early warning is sent out; and the other is that a transient fault event is generated at the triggering moment, and a fault alarm is sent when the power frequency voltage and current generate faults. The system can utilize GIS geographic information technology to automatically mark the fault point in the background of the system, and an operation and maintenance person can search and repair the fault point through longitude and latitude coordinates of the fault point position prompted by the system, so that measures are effectively taken to solve the cable fault;
the triggering conditions of the upper computer 41 are divided into two parts: part of the trigger conditions (1) are used for analyzing the high-frequency current waveforms uploaded by the lower computers 39 at the two ends of each submarine cable; part of the trigger conditions (2) are used for analyzing the power frequency current and voltage waveforms uploaded by the lower computers 39 at the two ends of each submarine cable;
trigger condition (1):
1. analyzing and judging the polarity of the waveform, wherein the polarity of the triggering moment in the high-frequency waveform file is the same as the polarity of the triggering moment in monitoring the transient fault in the submarine cable, and the polarity of the triggering moment in the high-frequency waveform file is opposite to the polarity of the triggering moment in monitoring the external fault of the submarine cable;
2. the time stamp information contained in the waveform file is integrated, and a transient fault event is formed when the time difference delta t between the time stamp information and the waveform file meets the following conditions:
0≤Δt≤L/v
wherein L is the whole length of the submarine cable; v is the wave velocity of the submarine cable traveling wave;
when the transient fault event meets the conditions, the system measures the fault point according to the trigger time difference delta t and the distance L between the devices by a D-type distance measuring principle;
trigger condition (2):
1. the waveform of the power frequency voltage and current is a 50HZ sine wave normally, and when a fault occurs instantaneously, the waveform generates a sudden change signal.
The submarine cable running state monitoring method has the beneficial effects that: compared with the original cable running state monitoring method, the method can implement early warning for transient ground faults before cable damage, can filter non-fault disturbance signals such as ship paths, switching gates and the like, effectively reduces system false alarms caused by disturbance, improves alarm accuracy and reduces false alarm rate. Specifically, the following steps: by monitoring the bus zero sequence voltage signal of the submarine cable to be tested and the transient current of the grounding conductor of the metal shielding layer, the method can:
1. the on-line fault early warning of the submarine cable can be realized, and the fault point distance can be clearly indicated;
2. the zero sequence voltage change of the power supply transformer can be monitored, the alarm accuracy is improved, and the fault false alarm rate is reduced;
3. the cable operation mode and structure are not changed, the existing system resources are not occupied, and the safety and reliability are realized.
Drawings
FIG. 1 is a block diagram of a submarine cable operational status monitoring device of the present invention;
FIG. 2 is a block diagram of the lower computer of the submarine cable running state monitoring device of the invention;
FIG. 3 is a flow chart of a lower computer of the submarine cable running state monitoring device of the invention;
FIG. 4 is a flow chart of the upper computer of the submarine cable running state monitoring device of the invention;
FIG. 5 is a chart of a plurality of event lists collected by the cloud platform of embodiment 2;
FIG. 6 is a diagram of accurate location of fault points in a GIS geographic information system in example 2;
FIG. 7 is a schematic diagram of traveling wave propagation;
fig. 8 is a waveform diagram when generating a sudden change signal.
Detailed Description
Embodiments of the invention are further described below with reference to the accompanying drawings:
example 1
The submarine cable running state monitoring device of the embodiment, referring to fig. 1-8, comprises a lower computer 39, a sensor 40 and an upper computer 41, wherein the sensor 40 and the upper computer 41 are in communication connection with the lower computer 39. The sensor 40 is used for carrying out real-time online acquisition on transient current signals and power frequency current signals and carrying out real-time online acquisition on zero-sequence voltage signals; the lower computer 39 is used for processing the signals acquired by the sensor 40 and uploading the acquired data to the upper computer 41; the upper computer 41 is used for analyzing and processing the data uploaded by the lower computer 39.
The sensor 40 includes a combined current sensor 12 and a voltage sensor 13, wherein the combined current sensor 12 is installed on the submarine cable body, and the voltage sensor 13 is installed on the secondary side of the submarine cable submarine connection point or transformer substation PT.
The lower computer 39 comprises a main control unit 1, and a current signal data acquisition unit 42, a voltage signal data acquisition unit 43, a time keeping module 5, a 4G communication module 6, a 485/CAN bus communication unit 7, a network port communication unit 8 and a power supply unit 11 which are in communication connection with the main control unit 1, wherein the current signal data acquisition unit 42 comprises a high-frequency current signal data acquisition unit 2 and a power frequency current signal data acquisition unit 3, the high-speed current signal data acquisition unit 2 and the power frequency current signal data acquisition unit 3 are in communication connection with a current signal interface unit 9, the voltage signal data acquisition unit 43 comprises a power frequency voltage signal data acquisition unit 4, the power frequency voltage signal data acquisition unit 4 is in communication connection with a voltage signal interface unit 10, the current signal interface unit 9 is connected with a combined current sensor 12, and the voltage signal interface unit 10 is connected with a voltage sensor 13.
The upper computer 41 includes a server 42, and analysis software for analyzing submarine cable faults is deployed in the server 42.
The main control unit 1 comprises a CPU14 with the model of ZYNQ7010, a 32-bit arm9 processor is arranged in the main control unit, and the main control unit is composed of the CPU14, an FPGA (field programmable gate array) programmable logic array 16 and a DDR2 memory 15, so that the functions of controlling data acquisition and time keeping, and data processing and forwarding are realized.
The time keeping module 5 comprises two parts, namely a GPS/Beidou time service module 17 and an optical fiber time service module 18, wherein one of the two is optionally configured in the CPU14, the GPS/Beidou time service module 17 adopts a U-blox module with time service precision reaching 10ns, the GPS antenna acquires time information and then converts the time information into PPS second pulses to be output to the main control unit 1 for time service, the optical fiber time service module 18 adopts an ethercat chip of backshoff, and the time service information is acquired through an optical fiber and then converted into PPS second pulses to be output to the main control unit 1 for time service.
The 4G communication module 6 and the main control unit 1 exchange data through a USB protocol, are connected with an antenna through an SMA antenna interface 19, and are provided with micro SIM card slots on the circuit; the 485/CAN bus communication unit 7 comprises a 485 signal conversion circuit 20 and a CAN bus conversion circuit 21, wherein the 485 signal conversion circuit 20 and the CAN bus conversion circuit 21 respectively exchange data with a 485 signal interface 22 and a CAN bus interface 23 and forward the data to the main control unit 1; the network port communication unit 8 is used for data interaction during network port connection, and is composed of gigabit network ports, and interacts with the main control unit 1 through a PHY protocol.
The high-frequency current signal acquisition unit 2 comprises a high-frequency current signal acquisition circuit 24 and a self-checking pulse circuit 25, wherein the high-frequency current signal acquisition circuit 24 is composed of an AMP signal processing circuit 26 and four paths of high-speed A/D conversion chips, and amplifies the high-frequency current traveling wave signals; the self-checking pulse circuit 25 is controllably generated by the main control unit 1 and is used for sending a self-checking pulse signal to the self-checking coil 36 for self-checking; the power frequency current signal acquisition unit 3 is composed of a two-stage integrating circuit 27 and an A/D conversion chip 28, and is used for realizing 0-5000A power frequency current acquisition; the power frequency voltage signal acquisition unit 4 comprises an AMP signal conditioning circuit 29 and a four-way A/D conversion chip 30, and acquires PT secondary side opening triangular voltage.
The current signal interface unit 9 and the voltage signal interface unit 10 are respectively composed of a 6pin current aviation plug interface 31 and a 6pin Phoenix master socket voltage interface 32 and are respectively used for connecting the combined current sensor 12 and the voltage sensor 13; the power supply unit 11 adopts the ADI power management chip 33 to supply power, is compatible with a power management function, and can realize seamless switching between a power supply and the backup battery 34; the voltage sensor 13 collects PT secondary side opening triangular voltage and is connected with the 6pin Phoenix master socket voltage interface 32 through the 6pin plug 35; the combined current sensor 12 is an open-close type, two groups of current transformers and a group of self-checking coils 36 are arranged in the combined current sensor, the two groups of current transformers are a power frequency current transformer 37 and a high frequency current transformer 38, the high frequency current transformer 38 and the power frequency current transformer 37 respectively collect high frequency current signals and power frequency current signals, the high frequency current transformers and the power frequency current signals do not interfere with each other, the self-checking coils 36 receive self-checking pulses of the lower computer 39 and then perform self-checking on the high frequency current transformer 38, and the voltage sensor 13 is an electromagnetic voltage sensor.
The monitoring method of the submarine cable running state monitoring device of the embodiment comprises the following steps:
1. mounting sensor
Two ends of each submarine cable line are respectively provided with a set of lower computer 39 and a combined current sensor 12;
specifically, the combined current sensor 12 is arranged on the submarine cable body, and transient current signals and power frequency current signals are collected and recorded on line in real time;
the voltage sensor 13 is arranged on the sea cable sea land connection point or the PT secondary side of the transformer substation, and zero-sequence voltage signals are acquired and recorded on line in real time through the voltage sensor 13;
2. lower computer initialization
After the lower computer 39 is started, the power supply unit 11 supplies power to other units of the lower computer 39, and then the lower computer 39 enters an initialization stage, wherein the time keeping part is precisely time-controlled by the time keeping module 5 according to the fact that the optical fiber time-controlling module 18 or the GPS time-controlling/Beidou time-controlling module 17 is arranged in the main control unit 1; in addition, a 485/CAN bus communication unit 7, a 4G communication module 6 or a network port communication unit 8 is selected according to the internal arrangement of the main control unit 1 to upload the heartbeat of the equipment to the upper computer 41;
3. self-checking
When the initialization is completed, the lower computer 39 sends a pulse signal to the combined current sensor 12 for self-checking by the self-checking pulse circuit 25, and sends a self-checking result to the upper computer 41;
4. on-line monitoring
The lower computer 39 enters an on-line monitoring stage, and the power frequency voltage current and the transient current acquired by the combined current sensor 12 and the voltage sensor 13 are acquired in real time through the high-frequency current signal data acquisition unit 2, the power frequency current signal data acquisition unit 3 and the power frequency voltage signal data acquisition unit 4;
let i be set For the set threshold value, when a certain signal is collected to meet that i is more than or equal to i set When the waveform amplitude reaches more than a threshold value (realized by a comparator in an FPGA), forming a waveform file for high-frequency current, power frequency voltage current and timestamp information in a certain specific time period before and after the triggering time, storing the waveform file into the DDR2 memory 15, then sending the file to the upper computer 41 by the lower computer 39, analyzing and processing the waveform file sent by the lower computer 39 after the upper computer 41 receives the waveform file, judging that a submarine cable fails when the triggering condition is met, and determining the fault alarm level, wherein the method comprises the following two steps: only a transient fault event is generated at the moment of triggering, but the power frequency voltage and current waveform does not prompt the generation of a fault, and then fault early warning is sent out; the other is that a transient fault event is generated at the moment of triggering, and a fault alarm is sent when the power frequency voltage and current generate faults, then the system can utilize the GIS geographic information technology to automatically mark the fault point position at the background of the system, and an operation and maintenance person can search and repair the fault point through longitude and latitude coordinates of the fault point position prompted by the system, so that measures are effectively taken to solve the cable fault;
the triggering conditions of the upper computer 41 are divided into two parts: part of the trigger conditions (1) are used for analyzing the high-frequency current waveforms uploaded by the lower computers 39 at the two ends of each submarine cable; part of the trigger conditions (2) are used for analyzing the power frequency current and voltage waveforms uploaded by the lower computers 39 at the two ends of each submarine cable;
trigger condition (1):
1. analyzing and judging the polarity of the waveform, wherein the polarity of the triggering moment in the high-frequency waveform file is the same as the polarity of the triggering moment in monitoring the transient fault in the submarine cable, and the polarity of the triggering moment in the high-frequency waveform file is opposite to the polarity of the triggering moment in monitoring the external fault of the submarine cable;
2. the time stamp information contained in the waveform file is integrated, and a transient fault event is formed when the time difference delta t between the time stamp information and the waveform file meets the following conditions:
0≤Δt≤L/v
wherein L is the whole length of the submarine cable; v is the wave velocity of the submarine cable traveling wave;
when the transient fault event meets the conditions, the system measures the fault point according to the trigger time difference delta t and the distance L between the devices by a D-type distance measurement principle.
Referring to fig. 7, F is a transient fault point, M, N is a line head and a line tail, and L is a line length.
Double-end method traveling wave ranging (D-type ranging principle): the time difference between the arrival of the initial traveling wave at both ends of the line measures the fault distance. The absolute time for the fault initial traveling wave surge to reach the bus M end and the line end N at the same propagation speed v is set to be T M And T N Then:
wherein: d (D) MF And D NF The distances from the M end and the N end to the fault point are respectively; l is the length of the line MN; Δt=t M -T N . Trigger condition (2): 1, the power frequency voltage and current waveform is normally 50HZ sine wave, and when a fault occurs instantly, the waveform can generate an abrupt change signal, see figure 8.
Example 2
The purpose of this embodiment is to verify the submarine cable operation state monitoring device failure alarm function, the failure ranging function, the failure positioning function, and the longitude and latitude display function of embodiment 1.
Preparing a submarine cable monitoring device 2 sleeve, a submarine cable monitoring background (cloud) and 1 faulty submarine cable line (wherein, phase A low-resistance faults, phase B faults and phase C broken faults) and performing the following test process:
1. separating the tested cable from the power grid, and shorting A, B two phases of a certain fault submarine cable line, wherein the B phase is used as a load;
2. sea cable monitoring devices are arranged at two ends of a tested line, wherein sensors of the monitoring devices are buckled on three-phase core wires of a sea cable line A, B, C;
3. preparing system background debugging;
4. a certain fault submarine cable line A is connected to a power grid, a tested cable is closed at the tail end after wiring is completed, and a tested cable fault point is discharged;
5. the system receives the fault waveform, pops up an alarm popup window and prompts the fault distance;
6. and (5) pulling the brake of the cable line to be tested, stopping power transmission, and recovering the site to a specified state.
1. System monitoring case description
After the test starts, the system receives hundreds of discharge waveforms, wherein 5 groups of waveforms satisfying the double-end ranging condition event show that the fault distances are similar, and the waveforms in the 5 groups are about 2980m away from the head end of the fault submarine cable.
Multiple groups of event list diagrams acquired by the system cloud platform are shown in figure 5
Further verification by looking at the event list shows that the calculated distance is consistent with the calculated distance of the system. The verification process is as follows:
when the fault occurs in the monitoring line, the system measures the fault point according to the trigger time difference delta t and the distance L between the devices by a D-type distance measuring principle.
As shown in fig. 7, F is a transient fault point, M, N is a line head and a line tail, and L is a line length.
Double-end method traveling wave ranging: initial initiationThe time difference between the traveling wave reaching the two ends of the line is used for measuring the fault distance. The absolute time for the fault initial traveling wave surge to reach the bus M end and the line end N at the same propagation speed v is set to be T M And T N Then:
wherein: d (D) MF And D NF The distances from the M end and the N end to the fault point are respectively; l is the length of the line MN; Δt=t M -T N . L is the full length 6200m, v=160m/microseconds, and taking the multiple sets of data time differences into the above formula, the fault distances are as follows:
the fault distance obtained by the above groups of data is averaged to find that the fault distance is at 2982.24m from the head end.
Further, under the condition that the submarine cable running direction is a straight line, the position of the fault point is accurately positioned through the GIS geographic information system, and the longitude and latitude of the fault position are obtained.
Note that: the longitude and latitude calculation precondition is that: assuming that the submarine cable is a straight line, the submarine cable is calculated by the whole submarine cable length 6200m and the submarine cable is calculated by 160 m/micro wave speed, wherein the difference of the velocity of the land cable with the shorter two ends is ignored. GIS geographic information system fault point accurate positioning map referring to figure 6.
2. Conclusion of the experiment
The sea cable monitoring system is used for successfully alarming faults in a sea cable test, fault waveform data are obtained, fault distance is displayed in a background of the system, longitude and latitude coordinates of fault points are positioned, the functions of the system are fully verified, and the system can be proved to play a role in monitoring sea cable faults.
Claims (7)
1. The monitoring method of the submarine cable running state monitoring device is characterized by comprising the following steps of:
1) Mounting sensor
Two ends of each submarine cable line are respectively provided with a set of lower computer and a combined current sensor;
specifically, a combined current sensor is arranged on a submarine cable body, and transient current signals and power frequency current signals are collected and recorded on line in real time;
the voltage sensor is arranged on the sea cable sea-land connection point or the PT secondary side of the transformer substation, and zero-sequence voltage signals are acquired and recorded on line in real time through the voltage sensor;
2) Lower computer initialization
After the lower computer is started, the power supply unit supplies power to other units of the lower computer, and then the lower computer enters an initialization stage, wherein the time service part selects an optical fiber time service module or a GPS time service/Beidou time service module to perform accurate time service according to the internal arrangement of the main control unit by the time service module; in addition, a 485/CAN bus communication unit, a 4G communication module or a network port communication unit is selected according to the internal arrangement of the main control unit to upload the heartbeat of the equipment to the upper computer;
3) Self-checking
After the initialization is finished, the lower computer sends a pulse signal to the combined current sensor by the self-checking pulse circuit for self-checking, and sends a self-checking result to the upper computer;
4) On-line monitoring
The lower computer enters an online monitoring stage, and the power frequency voltage current and the transient current acquired by the combined current sensor and the voltage sensor are acquired in real time through the high-frequency current signal data acquisition unit, the power frequency current signal data acquisition unit and the power frequency voltage signal data acquisition unit;
let i be set For the set threshold value, when a certain signal is collected to meet that i is more than or equal to i set When the waveform amplitude reaches more than a threshold value (realized by a comparator in an FPGA), the high-frequency current and the power frequency voltage in a certain specific time period before and after the triggering time are electrifiedThe flow and time stamp information form a waveform file and are stored in a DDR2 memory, then the lower computer sends the file to the upper computer, the upper computer analyzes and processes the waveform file sent by the lower computer, when the trigger condition is met, the submarine cable is judged to have faults, and the fault alarm level is determined and divided into the following two types: only a transient fault event is generated at the moment of triggering, but the power frequency voltage and current waveform does not prompt the generation of a fault, and then fault early warning is sent out; the other is that a transient fault event is generated at the moment of triggering, and a fault alarm is sent when the power frequency voltage and current generate faults, then the system can utilize the GIS geographic information technology to automatically mark the fault point position at the background of the system, and an operation and maintenance person can search and repair the fault point through longitude and latitude coordinates of the fault point position prompted by the system, so that measures are effectively taken to solve the cable fault;
the submarine cable running state monitoring device comprises a lower computer, a sensor and an upper computer, wherein the sensor and the upper computer are in communication connection with the lower computer;
the sensor is used for carrying out real-time online acquisition on transient current signals and power frequency current signals and carrying out real-time online acquisition on zero-sequence voltage signals;
the lower computer is used for processing signals acquired by the sensor and uploading the acquired data to the upper computer;
the upper computer is used for analyzing and processing data uploaded by the lower computer;
the lower computer comprises a main control unit, and a current signal data acquisition unit, a voltage signal data acquisition unit, a time service module, a 4G communication module, a 485/CAN bus communication unit, a network port communication unit and a power supply unit which are in communication connection with the main control unit, wherein the current signal data acquisition unit comprises a high-frequency current signal data acquisition unit and a power frequency current signal data acquisition unit, the high-frequency current signal data acquisition unit and the power frequency current signal data acquisition unit are in communication connection with a current signal interface unit, the voltage signal data acquisition unit comprises a power frequency voltage signal data acquisition unit, the power frequency voltage signal data acquisition unit is in communication connection with a voltage signal interface unit, the current signal interface unit is connected with a combined current sensor, and the voltage signal interface unit is connected with a voltage sensor;
the main control unit comprises a CPU with the model of ZYNQ7010, a 32-bit arm9 processor is arranged in the CPU, the FPGA and the DDR2 memory, and the main control unit realizes the functions of controlling data acquisition, timing and data processing and forwarding;
the time service module comprises two parts, namely a GPS/Beidou time service module and an optical fiber time service module, wherein one of the GPS/Beidou time service module and the optical fiber time service module is optionally configured in the CPU, the GPS/Beidou time service module adopts a U-blox module with time service precision reaching 10ns, the GPS/Beidou time service module obtains time information through a GPS antenna and then converts the time information into PPS second pulses to be output to a main control unit for time service, the optical fiber time service module adopts an ethercat chip of backshoff, and the GPS/Beidou time service module obtains the time service information through an optical fiber and then converts the time information into PPS second pulses to be output to the main control unit for time service.
2. The monitoring method of a submarine cable operation state monitoring device according to claim 1, wherein
The sensor comprises a combined current sensor and a voltage sensor, wherein the combined current sensor is arranged on the submarine cable body, and the voltage sensor is arranged on the PT secondary side of a submarine cable submarine-land connection point or a transformer substation.
3. The monitoring method of a submarine cable operation state monitoring device according to claim 1, wherein
The 4G communication module and the main control unit 1 exchange data through a USB protocol, are connected with an antenna through an SMA antenna interface, and are provided with micro SIM card slots on a circuit; the 485/CAN bus communication unit comprises a 485 signal conversion circuit and a CAN bus conversion circuit, wherein the 485 signal conversion circuit and the CAN bus conversion circuit respectively exchange data with a 485 signal interface and a CAN bus interface and forward the data to the main control unit; the network port communication unit is used for data interaction during network port connection, consists of gigabit network ports and interacts with the main control unit through a PHY protocol.
4. The monitoring method of a submarine cable operation state monitoring device according to claim 1, wherein
The high-frequency current signal data acquisition unit comprises a high-frequency current signal acquisition circuit and a self-checking pulse circuit, wherein the high-frequency current signal acquisition circuit consists of an AMP signal processing circuit and four paths of high-speed A/D conversion chips, and amplifies a high-frequency current traveling wave signal; the self-checking pulse circuit is used for controllably generating a pulse signal by the main control unit and sending the self-checking pulse signal to the self-checking coil for self-checking; the power frequency current signal acquisition unit consists of a two-stage integrating circuit and an A/D conversion chip, and is used for realizing 0-5000A power frequency current acquisition; the power frequency voltage signal acquisition unit comprises an AMP signal conditioning circuit and a four-way A/D conversion chip, and acquires PT secondary side opening triangular voltage.
5. The monitoring method of a submarine cable operation state monitoring device according to claim 1, wherein
The current signal interface unit and the voltage signal interface unit are respectively composed of a 6pin current aviation plug interface and a 6pin Phoenix master socket voltage interface and are respectively used for connecting a combined current sensor and a voltage sensor;
the power supply unit adopts an ADI power supply management chip to supply power, is compatible with a power supply management function, and can realize seamless switching between a power supply and a backup battery.
6. The monitoring method of a submarine cable operation state monitoring device according to claim 1, wherein
The voltage sensor collects PT secondary side opening triangular voltage and is connected with a 6pin Phoenix master socket voltage interface through a 6pin plug; the combined current sensor is an open-close type current transformer, two groups of current transformers and one group of self-checking coils are arranged in the combined current sensor, the two groups of current transformers are power frequency current transformers and high frequency current transformers, the high frequency current transformers and the power frequency current transformers respectively collect high frequency current signals and power frequency current signals, the high frequency current transformers and the power frequency current signals are not interfered with each other, the self-checking coils are used for self-checking the high frequency current transformers after receiving self-checking pulses of the lower computer, and the voltage sensor is an electromagnetic voltage sensor.
7. The monitoring method of a submarine cable operation state monitoring device according to claim 1, wherein
The triggering condition of the upper computer is divided into two parts: part of the trigger conditions (1) are used for analyzing the high-frequency current waveforms uploaded by the lower computers at the two ends of each submarine cable; one part is a triggering condition (2) when analyzing the power frequency current and voltage waveforms uploaded by the lower computers at the two ends of each submarine cable;
trigger condition (1):
a. analyzing and judging the polarity of the waveform, wherein the polarity of the triggering moment in the high-frequency waveform file is the same as the polarity of the triggering moment in monitoring the transient fault in the submarine cable, and the polarity of the triggering moment in the high-frequency waveform file is opposite to the polarity of the triggering moment in monitoring the external fault of the submarine cable;
b. the time stamp information contained in the waveform file is integrated, and a transient fault event is formed when the time difference delta t between the time stamp information and the waveform file meets the following conditions:
0≤Δt≤L/v
wherein L is the whole length of the submarine cable; v is the wave velocity of the submarine cable traveling wave;
when the transient fault event meets the conditions, the system measures the fault point according to the trigger time difference delta t and the distance L between the devices by a D-type distance measuring principle;
trigger condition (2):
a. the waveform of the power frequency voltage and current is a 50HZ sine wave normally, and when a fault occurs instantaneously, the waveform generates a sudden change signal.
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