CN114236315A - 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 field of submarine cable on-line monitoring. Including submarine cable, its characterized in that: whether transient faults occur in the submarine cable is judged by detecting whether transient signals of PT zero sequence voltage of the submarine cable bus are generated, fault early warning is carried out on the submarine cable by monitoring and recording electromagnetic transient signals flowing through the metal shielding layer and generated by the submarine cable, and the distance of fault points is indicated. The submarine cable fault positioning system monitors the running state of a submarine cable line on line in real time, realizes fault early warning and fault automatic positioning of the submarine cable in a fault transient process generated at the moment of submarine cable fault, and marks the position of a fault point on a background map of the system.
Description
Technical Field
The invention belongs to the field of submarine on-line 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 supply grid for the sea island, and the submarine cable is distributed in different sea areas, so that the safe operation, normal maintenance and fault first-aid repair of the submarine power cable are inconvenient. And the island power supply electric wire netting is mostly single power supply, and the sea cable circuit is the trunk of circuit, because the operational environment is abominable, the trouble that the ship breaks down and causes takes place occasionally, can cause the power failure of different degrees during the cable fault to fault point is seeked and is restoreed the difficulty, and the maintenance cycle length has seriously influenced the normal production life of island resident and the development of island economy.
The development of an online monitoring system for a submarine cable is an urgent problem to be solved for solving the problems of submarine cable running state monitoring and fault diagnosis and positioning at present.
Various methods such as a direct current superposition method, a direct current component method, a difference frequency method, a dielectric loss method, a local discharge method and the like exist in the online monitoring technology of the power cable at home and abroad, and therefore, some application experiences are accumulated. The on-line monitoring of cables in foreign countries has been carried out relatively early and in many cases in japan. As early as the 80 s, japan has been continuously researching and exploring this field and developed various diagnostic techniques such as a direct current component method, a superimposed voltage method, and a dielectric loss method. On-Line operating Cable monitors (OLCM- -On Line Cable Monitor) were developed by Nippon Sumitomo electric industries, Ltd. in the late 80 s. The instrument is divided into a fixed type and a portable type, and the main application condition is a grounding system of a neutral point of a power grid under the voltage grades of 33, 66 and 11 OkV. For a system with a neutral point of ungrounded, grounded through an arc suppression coil or grounded through a resistance, the adopted method is mainly a direct current superposition method. The start of online monitoring of XLPE cables in China is late and the development is relatively slow. In the early nineties, the Shanghai Cable research institute also started research work and conducted field tests. Whether the cable runs safely or not has great influence on the power system and various factories and mines, which is gradually emphasized by the power operation department.
At present, experts and scholars of colleges and universities represented by China academy of electric sciences, North China university of electric power, Western Ann university of transportation and Chongqing university in China have researches in different directions on the on-line monitoring technology of power cables, mainly adopt methods such as partial discharge monitoring, traveling wave distance measurement, harmonic component analysis and grounding wire current analysis, and basically stay in the research and experiment stages at present, and are not popularized and applied in power systems. On the whole, the on-line monitoring research on cable insulation faults at home and abroad is not mature. For a long-distance submarine cable line, the current ultrahigh-speed data acquisition chip is mature day by day, the Beidou/GPS time keeping precision also reaches the practical standard vertebra, and the implementation of the online monitoring and fault positioning by the traveling wave distance measurement method becomes feasible from the technical conditions.
At present, products aiming at power cable online monitoring and fault positioning are not industrially popularized abroad, a company with a leading technology is a Netherlands Kaima power overhaul company, a power cable operation monitoring center is distributed in the company, 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 blank all over the world at present.
Disclosure of Invention
According to the defects in the prior art, the invention aims to provide an online early warning method for transient faults of submarine cables, which implements online early warning on transient faults before cable damage, is convenient for power supply departments to overhaul in advance or in a plan manner and improves power supply reliability.
The submarine cable running state monitoring device 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 the transient current signal and the power frequency current signal and carrying out real-time online acquisition on the zero sequence voltage signal;
the lower computer 39 is used for processing signals collected by the sensor 40 and uploading collected 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 a submarine land connection point of the submarine cable or a PT secondary side of a transformer substation;
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 which are in communication connection with the main control unit 1, 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 submarine cable faults is deployed in the server 42;
preferably, the main control unit 1 comprises a CPU14 with model number ZYNQ7010, a 32-bit arm9 processor is built in the CPU14, and the main control unit is composed of the CPU14, an FPGA programmable logic array 16 and a DDR2 memory 15, and realizes functions of controlling data acquisition, and processing and forwarding data on time;
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, the GPS/beidou time service module 17 and the optical fiber time service module 18 are configured with any one of the GPS/beidou time service module 17 through a CPU14, the GPS/beidou time service module 17 adopts a U-blox module with time service precision reaching 10ns, the time information is acquired through a GPS antenna and then converted into PPS second pulses, the PPS second pulses are output to the main control unit 1 for time service, and the optical fiber time service module 18 adopts a backhaul ethercat chip, the time information is acquired through optical fibers and then converted into PPS second pulses, and the PPS second pulses are output to the main control unit 1 for time service;
preferably, data are exchanged between the 4G communication module 6 and the main control unit 1 through a USB protocol, the 4G communication module is connected with an antenna through an SMA antenna interface 19, and a micro SIM card slot is arranged on a 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, is composed of kilomega network ports, and interacts with the main control unit 1 through a PHY protocol;
preferably, the high-frequency current signal acquisition unit 2 includes a high-frequency current signal acquisition circuit 24 and a self-checking pulse circuit 25, and the high-frequency current signal acquisition circuit 24 is composed of an AMP signal processing circuit 26 and a four-way high-speed a/D conversion chip, and amplifies the high-frequency current traveling wave signal; the self-checking pulse circuit 25 is controllable by the main control unit 1 to generate a pulse signal, 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 realizes the power frequency current acquisition of 0-5000A; 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 the 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 mother seat 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 supplies power by using an ADI power management chip 33, 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 a PT secondary side open triangular voltage, and is connected to the 6pin phoenix ni socket voltage interface 32 through a 6pin plug 35; the combined current sensor 12 is of an open-close type, two groups of current transformers and a group of self-checking coils 36 are arranged inside the combined current sensor, the two groups of current transformers are power frequency current transformers 37 and high frequency current transformers 38, the high frequency current transformers 38 and the power frequency current transformers 37 respectively collect high frequency current signals and power frequency current signals, the high frequency current signals and the power frequency current signals do not interfere with each other, the self-checking coils 36 perform self-checking on the high frequency current transformers 38 after receiving self-checking pulses of a lower computer 39, and the voltage sensor 13 is an electromagnetic voltage sensor.
The invention discloses a monitoring method of a submarine cable running state monitoring device, which is characterized by comprising the following steps:
1. mounting sensor
Two ends of each submarine cable circuit are respectively provided with a set of lower computer 39 and a combined current sensor 12;
specifically, the combined current sensor 12 is installed on a submarine cable body, and transient current signals and power frequency current signals are acquired and recorded on line in real time;
installing a voltage sensor 13 at a sea cable sea-land connection point or a transformer substation PT secondary side, and carrying out real-time online acquisition and recording on zero-sequence voltage signals 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, then the lower computer 39 enters an initialization stage, wherein the time keeping part selects the optical fiber time service module 18 or the GPS time service/Beidou time service module 17 for accurate time service by the time keeping module 5 according to the internal arrangement of 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 arranged and selected to upload the heartbeat of equipment to the upper computer 41 according to the internal arrangement of the main control unit 1;
3. self-test
After the initialization is completed, the lower computer 39 sends a pulse signal to the combined current sensor 12 for self-checking through 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 online monitoring stage, and real-time acquisition is carried out on power frequency voltage current and transient current acquired by the combined current sensor 12 and the voltage sensor 13 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 isetFor a set threshold value, when a certain collected signal meets the condition that i is more than or equal to isetWhen the sea cable fault alarm device is used (the waveform amplitude reaches more than a threshold value and is realized through a comparator in an FPGA), a waveform file is formed by high-frequency current, power-frequency voltage current and timestamp information in a certain specific time period before and after the trigger moment and is stored in a DDR2 storage 15, then the lower computer 39 sends the file to the upper computer 41, the upper computer 41 carries out analysis processing after receiving the waveform file sent by the lower computer 39, the sea cable fault is judged when the trigger condition is met, and the fault alarm level is determined and divided into the following two types: one is that only transient fault event is generated at the triggering moment, but fault warning is sent out when the fault is not prompted to be generated by the power frequency voltage current waveform; and the other is that a transient fault event is generated at the triggering moment, and a fault alarm is sent out when a fault is generated by the power frequency voltage and current. The system can automatically mark the position of the fault point in the background of the system by utilizing a GIS geographic information technology, and operation and maintenance personnel can search and repair the fault point through the longitude and latitude coordinates of the position of the fault point prompted by the system, thereby effectively taking measures to solve the cable fault;
the trigger condition of the upper computer 41 is divided into two parts: one part is a trigger condition (I) when the high-frequency current waveform uploaded by the lower computers 39 at the two ends of each submarine cable loop is analyzed; one part is a trigger condition II when the power frequency current and voltage waveforms uploaded by the lower computers 39 at the two ends of each submarine cable loop are analyzed;
triggering conditions are as follows:
1. analyzing and judging the waveform polarity, and monitoring transient faults inside the submarine cable according to the same polarity of the triggering time in the high-frequency waveform file, and monitoring faults outside the submarine cable according to the opposite polarity;
2. and integrating the timestamp information contained in the waveform file, and forming a transient fault event when the time difference delta t between the two meets the following conditions:
0≤Δt≤L/v
wherein L is the total length of the submarine cable; v is the travelling wave velocity of the submarine cable;
when the transient fault event meets the conditions, the system carries out fault point ranging according to the difference value delta t of the triggering time and the distance L between the devices by a D-type ranging principle;
triggering condition (II):
1. the power frequency voltage and current waveform is normally 50HZ sine wave, and when a fault occurs instantaneously, the waveform generates an abrupt change signal.
The submarine cable running state monitoring method has the beneficial effects that: compared with the original method for monitoring the running state of the cable, the method can implement early warning aiming at transient grounding faults before the cable is damaged, can filter non-fault disturbance signals such as ship paths, switching on and switching off, and the like, effectively reduces system false alarms caused by disturbance, improves alarm accuracy and reduces false alarm rate. Specifically, the method comprises the following steps: by monitoring bus zero sequence voltage signals of the submarine cable to be detected and monitoring transient current of a grounding conductor of a metal shielding layer, the method can be used for:
1. the online fault early warning of the submarine cable can be realized, and the distance of a fault point 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 running mode and structure of the cable are not changed, the existing system resources are not occupied, and the cable is safe and reliable.
Drawings
Fig. 1 is a block diagram showing the structure of a submarine cable operation state monitoring apparatus according to the present invention;
FIG. 2 is a block diagram of the lower computer of the submarine cable operation state monitoring device according to the present invention;
FIG. 3 is a flow chart of the lower computer of the submarine cable running state monitoring device according to the present invention;
FIG. 4 is a flow chart of the upper computer of the submarine cable running state monitoring device according to the present invention;
fig. 5 is a list diagram of a plurality of groups of events collected by the cloud platform of the system in embodiment 2;
fig. 6 is a diagram of the accurate positioning of the fault point of the GIS geographic information system in embodiment 2;
FIG. 7 is a schematic of traveling wave propagation;
fig. 8 is a waveform diagram when an abrupt signal is generated.
Detailed Description
Embodiments of the invention are further described below with reference to the accompanying drawings:
example 1
The submarine cable operating condition monitoring device of the present embodiment, referring to fig. 1-8, includes a lower computer 39, and a sensor 40 and an upper computer 41 which are in communication connection with the lower computer 39. The sensor 40 is used for carrying out real-time online acquisition on the transient current signal and the power frequency current signal and carrying out real-time online acquisition on the zero sequence voltage signal; the lower computer 39 is used for processing signals collected by the sensor 40 and uploading collected 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 installed on the submarine cable body, and the voltage sensor 13 is installed on a submarine cable land connection point or a secondary side of 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 which are in communication connection with the main control unit 1, 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 the submarine cable fault is deployed in the server 42.
The main control unit 1 comprises a CPU14 with a model number of ZYNQ7010, a 32-bit arm9 processor is arranged in the CPU14, and the main control unit is composed of the CPU14, an FPGA programmable logic array 16 and a DDR2 memory 15, and realizes the functions of controlling data acquisition and processing and forwarding data in a timekeeping manner.
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 any one of the GPS/Beidou time service module 17 and the optical fiber time service module 18 is configured inside a CPU14, the GPS/Beidou time service module 17 adopts a U-block module with the time service precision reaching 10ns, the time information is obtained through a GPS antenna and then is converted into PPS second pulse to be output to the main control unit 1 for time service, and the optical fiber time service module 18 adopts a backhoff ethercat chip, the time service information is obtained through optical fibers and then is converted into PPS second pulse to be output to the main control unit 1 for time service.
Data are exchanged between the 4G communication module 6 and the main control unit 1 through a USB protocol, the 4G communication module is connected with an antenna through an SMA antenna interface 19, and a micro SIM card slot is arranged on a 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, 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 consists of an AMP signal processing circuit 26 and four high-speed A/D conversion chips and is used for amplifying high-frequency current traveling wave signals; the self-checking pulse circuit 25 is controllable by the main control unit 1 to generate a pulse signal, 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 realizes the power frequency current acquisition of 0-5000A; 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-open 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 mother seat 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 an ADI power management chip 33 for power supply, is compatible with a power management function, and can realize seamless switching between a power supply and a backup battery 34; the voltage sensor 13 collects PT secondary side opening triangular voltage and is connected with a 6pin Phoenix female seat voltage interface 32 through a 6pin plug 35; the combined current sensor 12 is of an open-close type, two groups of current transformers and a group of self-checking coils 36 are arranged inside the combined current sensor, the two groups of current transformers are power frequency current transformers 37 and high frequency current transformers 38, the high frequency current transformers 38 and the power frequency current transformers 37 respectively collect high frequency current signals and power frequency current signals, the high frequency current signals and the power frequency current signals do not interfere with each other, the self-checking coils 36 perform self-checking on the high frequency current transformers 38 after receiving self-checking pulses of a lower computer 39, and the voltage sensor 13 is an electromagnetic voltage sensor.
The monitoring method of the submarine cable running state monitoring device comprises the following steps:
1. mounting sensor
Two ends of each submarine cable circuit are respectively provided with a set of lower computer 39 and a combined current sensor 12;
specifically, the combined current sensor 12 is installed on a submarine cable body, and transient current signals and power frequency current signals are acquired and recorded on line in real time;
installing a voltage sensor 13 at a sea cable sea-land connection point or a transformer substation PT secondary side, and carrying out real-time online acquisition and recording on zero-sequence voltage signals 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, then the lower computer 39 enters an initialization stage, wherein the time keeping part selects the optical fiber time service module 18 or the GPS time service/Beidou time service module 17 for accurate time service by the time keeping module 5 according to the internal arrangement of 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 arranged and selected to upload the heartbeat of equipment to the upper computer 41 according to the internal arrangement of the main control unit 1;
3. self-test
After the initialization is completed, the lower computer 39 sends a pulse signal to the combined current sensor 12 for self-checking through 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 online monitoring stage, and real-time acquisition is carried out on power frequency voltage current and transient current acquired by the combined current sensor 12 and the voltage sensor 13 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 isetFor a set threshold value, when a certain collected signal meets the condition that i is more than or equal to isetWhen the sea cable fault alarm device is used (the waveform amplitude reaches more than a threshold value and is realized through a comparator in an FPGA), a waveform file is formed by high-frequency current, power-frequency voltage current and timestamp information in a certain specific time period before and after the trigger moment and is stored in a DDR2 storage 15, then the lower computer 39 sends the file to the upper computer 41, the upper computer 41 carries out analysis processing after receiving the waveform file sent by the lower computer 39, the sea cable fault is judged when the trigger condition is met, and the fault alarm level is determined and divided into the following two types: one is that only transient fault event is generated at the triggering moment, but fault warning is sent out when the fault is not prompted to be generated by the power frequency voltage current waveform; the other method is that a fault alarm is sent out when a transient fault event is generated at the moment of triggering and a fault is generated in the power frequency voltage and current, and then the systemThe GIS geographic information technology can be utilized to realize automatic marking of the fault point position in the system background, and operation and maintenance personnel can search and repair the fault point through the longitude and latitude coordinates of the fault point position prompted by the system, thereby effectively taking measures to solve the cable fault;
the trigger condition of the upper computer 41 is divided into two parts: one part is a trigger condition (I) when the high-frequency current waveform uploaded by the lower computers 39 at the two ends of each submarine cable loop is analyzed; one part is a trigger condition II when the power frequency current and voltage waveforms uploaded by the lower computers 39 at the two ends of each submarine cable loop are analyzed;
triggering conditions are as follows:
1. analyzing and judging the waveform polarity, and monitoring transient faults inside the submarine cable according to the same polarity of the triggering time in the high-frequency waveform file, and monitoring faults outside the submarine cable according to the opposite polarity;
2. and integrating the timestamp information contained in the waveform file, and forming a transient fault event when the time difference delta t between the two meets the following conditions:
0≤Δt≤L/v
wherein L is the total length of the submarine cable; v is the travelling wave velocity of the submarine cable;
when the transient fault event meets the conditions, the system carries out fault point ranging according to the difference value delta t of the triggering time and the distance L between the devices and by the D-type ranging principle.
Referring to fig. 7, F is the instantaneous fault point, M, N is the line head and tail, respectively, and L is the line length.
Double-end traveling wave ranging (D-type ranging principle): the time difference between the arrival of the initial traveling wave at the two ends of the line measures the fault distance. Setting the absolute time of the initial fault traveling wave surge to reach the M end of the bus and the tail end N of the line at the same propagation speed v as TMAnd TNAnd then:
in the formula: dMFAnd DNFRespectively the distances from the M end and the N end to a fault point; l is the length of the line MN; Δ t ═TM-TN. Triggering condition (II): 1, the power frequency voltage current waveform is normally 50HZ sine wave, and when the fault occurs instantaneously, the waveform can generate an abrupt change signal, see the attached figure 8.
Example 2
The purpose of this embodiment is to verify the fault alarm function, fault location function, and latitude and longitude display function of the submarine cable operating state monitoring device according to embodiment 1.
2 sets of submarine cable monitoring devices are prepared, a submarine cable monitoring background (cloud end) and 1 fault submarine cable line (wherein, a phase low resistance fault, a phase B fault and a phase C disconnection fault) are prepared, and the test process is as follows:
1. separating the tested cable from the power grid, and short-circuiting A, B two phases of a fault submarine cable line, wherein the B phase is used as a load;
2. installing submarine cable monitoring devices at two ends of a tested line, wherein monitoring device sensors are buckled on three-phase core wires of a submarine cable line A, B, C;
3. preparing background debugging of the system;
4. connecting a phase A of a certain fault submarine cable line into a power grid, switching on a tested cable at the tail end after the connection is finished, and discharging at a fault point of the tested cable;
5. the system receives the fault waveform, pops up an alarm popup window and prompts the fault distance;
6. and (5) switching off the tested submarine cable line, stopping power transmission, and recovering the site to a specified state.
Description of system monitoring condition
After the test is started, the system receives hundreds of discharge waveforms, wherein 5 groups of event waveforms meeting double-end ranging conditions show that the fault distances are close and are about 2980m away from the head end of the fault submarine cable.
FIG. 5 is a diagram of a list of events collected by a cloud platform
Further verification by viewing the event list is known to be consistent with the system calculated distance. The verification process is as follows:
when a fault occurs in the monitoring line, the system carries out fault point ranging according to the D-type ranging principle according to the difference value delta t of the triggering time and the distance L between the devices.
As shown in fig. 7, F is a transient fault point, M, N is a line head and a line tail, respectively, and L is a line length.
Double-end method traveling wave distance measurement: the time difference between the arrival of the initial traveling wave at the two ends of the line measures the fault distance. Setting the absolute time of the initial fault traveling wave surge to reach the M end of the bus and the tail end N of the line at the same propagation speed v as TMAnd TNAnd then:
in the formula: dMFAnd DNFRespectively the distances from the M end and the N end to a fault point; l is the length of the line MN; Δ T ═ TM-TN. L is the total length 6200m, v is 160 m/microsecond, and the fault distances are shown as follows by taking the time difference of multiple groups of data into the above formula:
the mean value of the fault distances obtained by the above multiple sets of data shows that the fault distance is at 2982.24m from the head end.
Further, under the condition that the trend of the submarine cable is a straight line, the position of the fault point is accurately positioned through the positioning of the GIS, and the longitude and the latitude of the fault position are obtained.
Note: the above longitude and latitude calculation premises are as follows: assuming the submarine cable is a straight line, the wave velocity is calculated by the total length 6200m of the submarine cable and is calculated by the wave velocity of 160 m/microsecond, wherein the wave velocity difference of the short crosslinked polyethylene terrestrial cables at the two ends is ignored. The GIS geographic information system fault point accurate positioning map refers to the attached figure 6.
Second, experimental conclusion
The submarine cable monitoring system is utilized to test a certain fault submarine cable, the system successfully alarms the fault, fault waveform data is obtained, fault distance is displayed on a system background, longitude and latitude coordinates of a fault point are positioned, system functions are fully verified, and the system can monitor the submarine cable fault.
Claims (10)
1. The submarine cable running state monitoring device is characterized by comprising 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 the transient current signal and the power frequency current signal and carrying out real-time online acquisition on the zero sequence voltage signal;
the lower computer is used for processing signals acquired by the sensor and uploading acquired data to the upper computer;
the upper computer is used for analyzing and processing data uploaded by the lower computer.
2. Submarine cable operating condition 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 a submarine cable land and sea connection point or a transformer substation PT secondary side.
3. Submarine cable operating condition monitoring device according to claim 2, wherein
The lower computer comprises a main control unit and a current signal data acquisition unit in communication connection with the main control unit, a voltage signal data acquisition unit, a time-keeping module, a 4G communication module, a 485/CAN bus communication unit, a network port communication unit and a power supply 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-speed current signal data acquisition unit, the power frequency current signal data acquisition unit and the current signal interface unit are in communication connection, 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 the 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.
4. Submarine cable operating condition monitoring device according to claim 3, wherein
The main control unit comprises a CPU with the model of ZYNQ7010, a 32-bit arm9 processor is arranged in the CPU, the main control unit comprises the CPU, an FPGA programmable logic array and a DDR2 memory, and the functions of controlling data acquisition, processing and forwarding data are realized in a time-keeping manner;
the time keeping module comprises a GPS/Beidou time service module and an optical fiber time service module, wherein the GPS/Beidou time service module and the optical fiber time service module are respectively arranged in a CPU, one of the GPS/Beidou time service module and the optical fiber time service module is selected from the GPS/Beidou time service module through the internal configuration of the CPU, the GPS/Beidou time service module adopts a U-blox module with the time service precision reaching 10ns, the time information is obtained through a GPS antenna and then converted into PPS second pulse, the PPS second pulse is output to the main control unit for time service, and the optical fiber time service module adopts a backhoff ethercat chip, the time service information is obtained through optical fibers and then converted into the PPS second pulse, and the PPS second pulse is output to the main control unit for time service.
5. Submarine cable operating condition monitoring device according to claim 3, wherein
Data are interacted between the 4G communication module and the main control unit 1 through a USB protocol, the 4G communication module is connected with an antenna through an SMA antenna interface, and a micro SIM card slot is arranged on a circuit; the 485/CAN bus communication unit comprises a 485 signal conversion circuit and a CAN bus conversion circuit, 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, is composed of gigabit network ports and interacts with the main control unit through a PHY protocol.
6. Submarine cable operating condition monitoring device according to claim 1, wherein
The high-frequency current signal 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 a four-way high-speed A/D conversion chip and is used for amplifying a high-frequency current traveling wave signal; the self-checking pulse circuit is controllable by the main control unit to generate a pulse signal and is used for sending a 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 the acquisition of the power frequency current of 0-5000A; the power frequency voltage signal acquisition unit comprises an AMP signal conditioning circuit and a four-way A/D conversion chip and is used for acquiring PT secondary side opening triangular voltage.
7. Submarine cable operating condition monitoring device according to claim 3, 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 female seat voltage interface and are respectively used for connecting the combined current sensor and the combined voltage sensor;
the power supply unit adopts an ADI power management chip to supply power, is compatible with a power management function, and can realize seamless switching between a power supply and a backup battery.
8. Submarine cable operating condition monitoring device according to claim 3, wherein
The voltage sensor collects PT secondary side opening triangular voltage and is connected with a 6pin Phoenix female seat voltage interface through a 6pin plug; the combined current sensor is of an open-close type, two groups of current transformers and a group of self-checking coils are arranged inside 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 do not interfere with each other, the self-checking coils perform self-checking on the high-frequency current transformers after receiving self-checking pulses of a lower computer, and the voltage sensor is an electromagnetic voltage sensor.
9. A method of monitoring an installation for monitoring the operational condition of a submarine cable according to any one of claims 1 to 8, comprising the steps of:
1) mounting sensor
Two ends of each submarine cable circuit are respectively provided with a set of lower computer and a combined current sensor;
specifically, the combined current sensor is arranged on a submarine cable body, and transient current signals and power frequency current signals are acquired and recorded on line in real time;
installing a voltage sensor at a sea cable sea-land connection point or a PT secondary side of a transformer substation, and carrying out real-time online acquisition and recording on zero-sequence voltage signals 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, then the lower computer enters an initialization stage, and the time keeping part selects an optical fiber time service module or a GPS time service/Beidou time service module to carry out accurate time service according to the internal arrangement of the main control unit by the time keeping module; in addition, a 485/CAN bus communication unit, a 4G communication module or a network port communication unit CAN be selected according to the internal arrangement of the main control unit to upload equipment heartbeat to an upper computer;
3) self-test
After the initialization is completed, the lower computer sends a pulse signal to the combined current sensor for self-checking through the self-checking pulse circuit, and sends a self-checking result to the upper computer;
4) on-line monitoring
The lower computer enters an online monitoring stage, and power frequency voltage current and transient current acquired by the combined current sensor and 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 isetFor a set threshold value, when a certain collected signal meets the condition that i is more than or equal to isetWhen the waveform amplitude reaches above a threshold value, the waveform amplitude is realized through a comparator in the FPGA, a waveform file formed by high-frequency current, power frequency voltage current and timestamp information in a certain specific time period before and after the trigger time is stored in a DDR2 memory, then a lower computer sends the file to an upper computer, the upper computer analyzes and processes the received waveform file sent by the lower computer, and when the waveform amplitude reaches above the threshold value, the waveform amplitude is realized through a comparator in the FPGAWhen the trigger condition is met, the submarine cable is judged to have a fault, and the fault alarm level is determined and divided into the following two types: one is that only transient fault event is generated at the triggering moment, but fault warning is sent out when the fault is not prompted to be generated by the power frequency voltage current waveform; the other type is that a transient fault event is generated at the trigger moment and a fault is generated by the power frequency voltage and current, a fault alarm is sent out, then the system can utilize the GIS geographic information technology to realize automatic marking of the position of the fault point in the background of the system, and operation and maintenance personnel can search and repair the fault point through the longitude and latitude coordinates of the position of the fault point prompted by the system, so that the cable fault is solved by effectively taking measures.
10. A method of monitoring a submarine cable according to claim 9, wherein said method comprises
The trigger condition of the upper computer is divided into two parts: one part is a trigger condition I when the high-frequency current waveforms uploaded by the lower computers at the two ends of each submarine cable are analyzed; one part is a trigger condition II when the power frequency current and voltage waveforms uploaded by the lower computers at the two ends of each submarine cable are analyzed;
triggering conditions are as follows:
1. analyzing and judging the waveform polarity, and monitoring transient faults inside the submarine cable according to the same polarity of the triggering time in the high-frequency waveform file, and monitoring faults outside the submarine cable according to the opposite polarity;
2. and integrating the timestamp information contained in the waveform file, and forming a transient fault event when the time difference delta t between the two meets the following conditions:
0≤Δt≤L/v
wherein L is the total length of the submarine cable; v is the travelling wave velocity of the submarine cable;
when the transient fault event meets the conditions, the system carries out fault point ranging according to the difference value delta t of the triggering time and the distance L between the devices by a D-type ranging principle;
triggering condition (II):
1. the power frequency voltage and current waveform is normally 50HZ sine wave, and when a fault occurs instantaneously, the waveform generates an abrupt change signal.
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