CN103513147B - A kind of undersea cable real-time monitoring system and monitoring method - Google Patents

Abstract

The invention discloses a submarine cable real-time monitoring system and a monitoring method in the technical field of measurement. Its technical solution is to design a real-time monitoring system for submarine cables, and to realize the temperature and strain during the operation of submarine cables by detecting the polarization state and phase of back Rayleigh scattered light, so as to realize external damage, insulation degradation, leakage, grounding faults, etc. Real-time monitoring of status information. It not only improves the utilization rate of the equipment, reduces the monitoring cost, but also greatly reduces the rate of false positives and misjudgments. Safe and stable operation is of great significance.

Description

A submarine cable real-time monitoring system and monitoring method

technical field

The invention belongs to the technical field of measurement, and in particular relates to a real-time monitoring system and method for a submarine cable.

Background technique

my country has a coastline of 32,000 kilometers, more than 6,500 large and small islands, and a territorial sea area of about 4.73 million square kilometers. There are many offshore working platforms. Submarine cables are used in remote power supply, high-voltage power transmission, power communication, signal transmission, and guarantee the production and life of island residents. It plays a key role in the normal operation of offshore working platforms.

Due to seawater erosion, erosion and other factors, it is easy to cause the insulation aging and water resistance of submarine cables to deteriorate, causing leakage currents in submarine cables, which will cause the temperature of submarine cables to rise at the fault point, and cause greater faults. , For example: ground short circuit fault, etc. The change of the load current of the submarine cable will also change the temperature of the submarine cable, that is, the change of the temperature of the submarine cable can reflect the operation status of the submarine cable. In order to make the submarine cable operate in a safe temperature range and prolong the service life of the submarine cable, there are It is necessary to carry out daily monitoring and maintenance on the health status of submarine cables.

With the increasing activities of marine development and utilization, the influence of breeding, fishing nets, anchors, etc. in the sea area on the operation of submarine cables cannot be ignored. There is no early warning in the event of damage, the accurate positioning of the accident point, the confirmation of the ship involved in the accident, and the difficulty in salvaging the broken cable end have affected the emergency repair of the accident and the settlement of losses. Therefore, it is of great significance to study new methods and means of submarine cable health monitoring to ensure the safe and stable operation of the power grid and build a strong smart grid.

In the submarine cable monitoring system, the traditional optical time domain reflector (OTDR) uses the back Rayleigh scattering signal generated by the transmission of light in the optical fiber to locate the submarine cable fault point, but this technology can only be used when the submarine cable has been violated. It is impossible to realize the real-time online monitoring of violation events after the incident damages and breaks are detected. The Optical Time Domain Backscattering Distributed Optical Fiber Sensor (ROTDR) uses the back Raman scattering signal in the multimode optical fiber to measure the temperature distribution along the optical fiber, which cannot achieve strain measurement, so this technology can only realize the temperature information of the submarine cable. Online monitoring, it is impossible to conduct online monitoring of contingency events such as anchor dropping and ship towing. Therefore, there is an urgent need for an effective real-time online monitoring method for submarine cables.

Contents of the invention

Aiming at the problem that the traditional submarine cable monitoring system mentioned in the background technology cannot realize online monitoring of the temperature and strain during the operation of the submarine cable, the present invention proposes a real-time monitoring system and monitoring method for the submarine cable.

A submarine cable real-time monitoring system is characterized in that the system includes a narrow-spectrum light source, a first coupler, a polarization controller PC, an electro-optical modulator EOM, a pulse generator, a first isolator, and a first erbium-doped fiber amplifier EDFA, second isolator, first optical filter, circulator, polarizer, sensing fiber, second coupler, second erbium-doped fiber amplifier EDFA, analyzer, third isolator, second optical filter device, a first photodetector, a second photodetector, a data acquisition and display unit and a clock control unit;

Wherein, the narrow-spectrum light source, the first coupler, the polarization controller PC, the electro-optic modulator EOM, the first isolator, the first erbium-doped fiber amplifier EDFA, the second isolator, the first optical filter, the circulator, The polarizer and the sensing fiber are connected in sequence; the narrow-spectrum light source is used to generate narrow-spectrum light; the function of the first coupler is to couple the laser pulse emitted by the laser into the polarization controller PC; the electro-optic modulator The EOM is used to modulate the pulsed light; the first isolator is used to prevent the reverse transmission of the pulsed light from causing damage to the narrow-spectrum light source and ensure the unidirectional transmission of the pulsed light; the first erbium-doped fiber amplifier EDFA is used to amplify the pulsed light ; The second isolator is used to prevent the reverse transmission of the pulsed light from causing damage to the narrow-spectrum light source, and to ensure the unidirectional transmission of the pulsed light; Radiation noise; the function of the polarizer is to convert ordinary optical signals into linearly polarized light;

The pulse generator is respectively connected with the clock control unit and the electro-optic modulator EOM; the pulse generator is used to generate a pulse signal, and the narrow-spectrum light is modulated by the electro-optic modulator EOM to make it into pulsed light;

The clock control unit is respectively connected with the narrow-spectrum light source and the data acquisition and display unit; the data acquisition and display unit is used to extract the polarization state and phase information of the Rayleigh scattered light signal, and perform calculation and display;

The second coupler is respectively connected with the circulator, the second erbium-doped fiber amplifier EDFA and the polarizer; the second coupler is to divide the back Rayleigh scattering signal into two paths; the second erbium-doped fiber The optical fiber amplifier EDFA is used to amplify the received light; the analyzer is used to detect the polarization state;

The second erbium-doped fiber amplifier EDFA, the third isolator, the second optical filter, the first photodetector and the data acquisition and display unit are connected in sequence; the third isolator is used to prevent the reverse transmission of pulsed light to the The narrow-spectrum light source causes damage to ensure the one-way transmission of pulsed light; the first photodetector is used to convert the received optical signal into an electrical signal;

The polarizer, the second photodetector and the data acquisition and display unit are sequentially connected; the second photodetector is used to convert the received optical signal into an electrical signal.

The spectral width of the narrow-spectrum light source is 3 kHz to 12.5 GHz.

The system uses indirect modulation to modulate the laser light generated by the narrow-spectrum light source into pulsed light.

The first optical filter includes an optical circulator and a fiber Bragg grating; the bandwidth of the first optical filter is equal to the spectral width of the light source.

The second optical filter includes an optical circulator and a fiber Bragg grating; the bandwidth of the second optical filter is equal to the spectral width of the light source.

A method for real-time monitoring of submarine cables, characterized in that said method specifically comprises the following steps:

Step 1: Connect the single-mode optical fiber in the photoelectric composite submarine cable to the submarine cable real-time monitoring system as the sensing optical fiber, or wind the communication optical cable on the ordinary submarine cable for measurement, and use the single-mode optical fiber in the communication optical cable as the transmission Sensing optical fiber access submarine cable real-time monitoring system;

Step 2: The submarine cable real-time monitoring system injects pulsed light into the single-mode fiber to generate Rayleigh scattering in the single-mode fiber;

Step 3: The submarine cable real-time monitoring system realizes the monitoring of the polarization state and phase according to the phase information of the forward transmitted light at the reflection point of the Rayleigh scattered light returned by different parts of the single-mode fiber;

Step 4: Extract the polarization state and phase information of the Rayleigh scattered light signal through the data acquisition and display unit of the submarine cable real-time monitoring system, and realize the temperature and strain information monitoring along the single-mode optical fiber;

Step 5: Analyze the operating status of the submarine cable through changes in temperature and strain, and realize real-time online monitoring of the submarine cable.

The beneficial effect of the present invention is that the temperature and strain during the operation of the submarine cable can be realized by detecting the polarization state and phase of Rayleigh scattered light, so as to realize the real-time monitoring of state information such as external damage, insulation degradation, leakage, and grounding fault . It not only improves the utilization rate of the equipment, reduces the monitoring cost, but also greatly reduces the rate of false positives and misjudgments. Safe and stable operation is of great significance.

Description of drawings

Fig. 1 is the connection diagram that adopts submarine cable real-time monitoring system online monitoring submarine cable state information provided by the present invention; Wherein, a is the measurement connection diagram of photoelectric composite submarine cable; b is the communication optical cable wound on the common submarine cable for measurement Connection Diagram;

Fig. 2 is the structural diagram of the submarine cable real-time monitoring system provided by the present invention;

Among them, 1-submarine cable real-time monitoring system; 2-photoelectric composite submarine cable; 3-composite single-mode optical fiber in photoelectric composite submarine cable; 4-common submarine cable; 5-single-mode optical fiber in communication optical cable; 6-the first Coupler; 7-first isolator; 8-second isolator; 9-circulator; 10-polarizer; 11-fiber Bragg grating; 12-third isolator; 13-sensing fiber; 14 second coupler.

detailed description

The preferred embodiments will be described in detail below in conjunction with the accompanying drawings. It should be emphasized that the following description is only exemplary and not intended to limit the scope of the invention and its application.

Fig. 1 is the connection diagram that adopts submarine cable real-time monitoring system online monitoring submarine cable state information that the present invention provides; Wherein, a is the measurement connection diagram of photoelectric composite submarine cable, and submarine cable real-time monitoring system 1 is directly connected with photoelectric composite submarine cable 2 Composite single-mode optical fiber 3 is connected; b is a connection diagram of winding a communication optical cable on an ordinary submarine cable for measurement, and the submarine cable real-time monitoring system 1 is connected to the single-mode optical fiber 5 in the communication optical cable.

Fig. 2 is a structural diagram of the submarine cable real-time monitoring system provided by the present invention. In Figure 2, Rayleigh scattered light phase detection generally requires a very narrow spectral width, and an ultra-narrow linewidth laser is used. Because if the spectral width of the laser is large, the generated laser pulses contain various spectral components, and the Rayleigh backscattering of these signals will emit superposition when they reach the detector at the same time, rather than the interference of the ultra-narrow linewidth laser. Select a suitable semiconductor laser as the light source. In order to simultaneously detect the phase and polarization state of Rayleigh scattered light, it is necessary to carefully select the spectral width of the light source. The spectral width must be selected between 3kHz and 12.5GHz, which can ensure the occurrence of interference effect The interference effect must also not be so strong as to completely overwhelm the effect of polarization modulation.

In order to realize distributed measurement, pulsed light needs to be injected into the sensing fiber, and the system modulates the laser light into pulsed light through indirect modulation. The clock control unit triggers the narrow-spectrum light source to make it generate narrow-spectrum light suitable for system detection. At the same time, the clock control unit triggers the pulse generator, and the pulse generator starts to work to generate a pulse signal that meets the system requirements. The pulse signal is used to modulate the narrow-spectrum light through the electro-optical modulator to make it into pulsed light. In order to prevent the reverse transmission of the pulsed light from causing damage to the narrow-spectrum light source, a first isolator is added to ensure the unidirectional transmission of the pulsed light in the optical fiber. After the continuous light is modulated into a pulsed optical signal, the optical power is low, and it needs to be amplified by the first erbium-doped fiber amplifier EDFA. The first erbium-doped fiber amplifier EDFA will introduce spontaneous emission noise to the system, and it needs to go through a bandwidth equal to the spectral width of the light source. The first optical filter filters out the noise signal, and the optical filter is composed of an optical circulator and a fiber Bragg grating. The denoised pulsed light is injected into the sensing fiber through the c-port of the circulator. When light is transmitted in the optical fiber, Rayleigh scattering will occur. The Rayleigh scattering signal that occurs in the back direction travels along the optical fiber and reaches the d port of the circulator. The scattered light is transmitted in one direction in the circulator and output through the e port. The backscattered light of the coupler is equally divided into two paths through the f port of the coupler. The optical signal at port g of the second coupler is amplified and filtered by the second erbium-doped fiber amplifier EDFA, and then directly sent to the first photodetector for photoelectric conversion. The optical signal at port h of the coupler passes through an analyzer to detect the polarization state and then passes through the second Photodetectors convert this into an electrical signal. Since the polarization state of the scattered light at the reflection point is exactly the same as that of the forward transmission light, the back Rayleigh scattered light carries the polarization information of the forward transmission light at the scattering point, so the scattering point can be known by detecting the polarization information status information at . At the same time, the Rayleigh scattered light returned from different parts of the optical fiber also carries the phase information of the forward transmitted light at the reflection point. After interference, the power of this beam of Rayleigh scattered light back will also be modulated by the phase. Becomes a certain regular fluctuation, so the state information at the scattering point can be known by detecting the phase information. The clock control unit controls the data acquisition and display unit to collect two optical signals and perform denoising and other processing to extract the polarization state and phase information of the Rayleigh scattered optical signal, thereby realizing temperature and strain information monitoring along the optical fiber. Finally, the operating state of the submarine cable is analyzed through the changes of temperature and strain, so as to realize the real-time online monitoring of the submarine cable.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (6)

1. a undersea cable real-time monitoring system, it is characterized in that, described system comprises narrow spectrum light source, the first coupling mechanism, Polarization Controller PC, electrooptic modulator EOM, surge generator, the first shield retaining, the first erbium-doped optical fiber amplifier EDFA, the 2nd shield retaining, the first optical filter, annular device, the polarizer, sensor fibre, the 2nd coupling mechanism, the 2nd erbium-doped optical fiber amplifier EDFA, analyzer, the 3rd shield retaining, the 2nd optical filter, the first photoelectric detector, the 2nd photoelectric detector, data acquisition and display unit and clock control cell;

Wherein, described narrow spectrum light source, the first coupling mechanism, Polarization Controller PC, electrooptic modulator EOM, the first shield retaining, the first erbium-doped optical fiber amplifier EDFA, the 2nd shield retaining, the first optical filter, annular device, the polarizer and sensor fibre connect in turn; Described narrow spectrum light source is for generation of narrow spectrum light; The effect of described first coupling mechanism is that the laser pulse that laser apparatus is launched is coupled into Polarization Controller PC; Described electrooptic modulator EOM is for modulating pulse light; Described first shield retaining is used for preventing pulse light reverse transfer from narrow spectrum light source is caused infringement, ensures pulse light one way transmission; Described first erbium-doped optical fiber amplifier EDFA is used for paired pulses light and amplifies; Described 2nd shield retaining is used for preventing pulse light reverse transfer from narrow spectrum light source is caused infringement, ensures pulse light one way transmission; Described first optical filter is used for the spontaneous emission noise that filtering first erbium-doped optical fiber amplifier EDFA is introduced to system; The effect of the described polarizer converts common optical signal to line polarized light;

Described surge generator is connected with described clock control cell and electrooptic modulator EOM respectively; Described surge generator, for generation of pulse signal, modulates narrow spectrum light by electrooptic modulator EOM so that it is become pulse light;

Described clock control cell is connected with described narrow spectrum light source and data acquisition and display unit respectively; Described data acquisition and display unit is for extracting polarization state and the phase place information of Rayleigh scattering optical signal, and carries out calculating and showing;

Described 2nd coupling mechanism is connected with described annular device, the 2nd erbium-doped optical fiber amplifier EDFA and analyzer respectively; Described 2nd coupling mechanism is that back rayleigh scattering signal is divided into two-way; The light received is amplified by described 2nd erbium-doped optical fiber amplifier EDFA; Described analyzer is for detecting polarization state;

Described 2nd erbium-doped optical fiber amplifier EDFA, the 3rd shield retaining, the 2nd optical filter, the first photoelectric detector and data acquisition and display unit connect in turn; Described 3rd shield retaining is used for preventing pulse light reverse transfer from narrow spectrum light source is caused infringement, ensures pulse light one way transmission; Described first photoelectric detector is for turning into electrical signal by the optical signal received;

Described analyzer, the 2nd photoelectric detector and data acquisition and display unit connect in turn; Described 2nd photoelectric detector is for turning into electrical signal by the optical signal received.

2. a kind of undersea cable real-time monitoring system according to claim 1, it is characterised in that, described narrow spectrum light source spectrum width is 3kHz��12.5GHz.

3. a kind of undersea cable real-time monitoring system according to claim 1, it is characterised in that, described system adopts the mode of modulation indirectly that the Laser Modulation that narrow spectrum light source produces is become pulse light.

4. a kind of undersea cable real-time monitoring system according to claim 1, it is characterised in that, described first optical filter comprises optical circulator and Fiber Bragg Grating FBG; Described first optical filter bandwidth equals light source spectrum width.

5. a kind of undersea cable real-time monitoring system according to claim 1, it is characterised in that, described 2nd optical filter comprises optical circulator and Fiber Bragg Grating FBG; Described 2nd optical filter bandwidth equals light source spectrum width.

6. a kind of undersea cable real-time monitoring system according to claim 1, it is characterised in that, the monitoring method of described system specifically comprises the following steps:

Step 1: the single-mode fiber in photoelectric composite sea cable is accessed undersea cable real-time monitoring system as sensor fibre, or be wrapped on conventional ocean cable by communications optical cable to measure, the single-mode fiber in communications optical cable is accessed undersea cable real-time monitoring system as sensor fibre;

Step 2: undersea cable real-time monitoring system, to injected pulse light in single-mode fiber, produces Rayleigh scattering in single-mode fiber;

Step 3: the Rayleigh scattering light that undersea cable real-time monitoring system returns according to part different in single-mode fiber is with the phase place information of reflection spot place fl transmission light, it is achieved the monitoring of polarization state and phase place;

Step 4: polarization state and the phase place information being extracted Rayleigh scattering optical signal by undersea cable real-time monitoring system data acquisition and display unit, it is achieved the temperature that single-mode fiber is along the line and strain information monitoring;

Step 5: the running status being analyzed undersea cable by the change of temperature and strain, it is achieved the real time on-line monitoring of undersea cable.