A multi-source fault detection and identification method for DC power supply cables of submarine observation networks

Abstract

The present invention discloses a multi-source fault detection and identification method for a DC power supply cable of a submarine observation network. The multi-source fault detection and identification method for the DC power supply cable can achieve the purpose of detecting and identifying multiple types of faults and multi-point faults of the DC power supply cable, including the connection of the multi-source fault detection loop of the submarine observation network cable, the detection and data acquisition of the DC power supply cable, the establishment of a fault model for a long-distance power transmission cable, and the judgment of multi-source fault detection results, etc. The beneficial effect of the present invention is that it can accurately, safely, real-timely, and efficiently detect and identify multiple types of faults and multi-point faults of the DC power supply cable, provide scientific and reliable data for the maintenance and repair of the energy supply network of the submarine observation network, and realize its long-term reliable operation.

Description

Technical Field

[0001] The present invention relates to the field of multi-source fault detection of power supply cables, and particularly to a method for multi-source fault detection and identification of DC power supply cables in a submarine observation network. Background Art

[0002] As the third earth science observation platform established by humans, through the submarine observation network, humans can penetrate deep into the ocean to observe and understand the ocean. At present, China has established submarine observation systems in the East China Sea and the South China Sea respectively, realizing all-weather, real-time and high-resolution multi-interface three-dimensional comprehensive observation from the seabed to the sea surface in the East China Sea and the South China Sea of China, providing long-term continuous observation data and in-situ scientific experiment platforms for in-depth understanding of the marine environment in the East China Sea and the South China Sea. With the continuous deepening of research, the submarine observation network is gradually expanding from the coastal area to the open sea area, and the reliability of its power supply has faced new challenges. As the most common form of power supply for the submarine observation network, the operation reliability of long-distance DC power supply cables has become increasingly critical. In addition, in the open sea area, the submarine observation network increasingly adopts the form of local energy extraction or offshore new energy power generation for maintenance. However, due to the uneven distribution of new energy forms such as offshore wind power, photovoltaic power, tides, and submarine geothermal energy, which are greatly affected by the environment, it is necessary to form a power supply network on the seabed to reasonably allocate the power distribution in different regions, improve the energy utilization rate, and also increase the operation duration of the submarine observation network. To achieve the above goals, DC power supply cables become even more important, and their safe and reliable operation will greatly enhance the continuous detection ability of the submarine observation network.

[0003] However, it must be noted that the environment in the open sea area is complex and changeable, the seabed topography is more rugged, and the seabed geological activities are frequent, with strong biological damage and seawater corrosion. Due to the unclear specific situation of the seabed, the laid DC power supply cables have not been well protected, resulting in frequent occurrence of power supply cable operation failures. Since the length of general DC power supply cables usually reaches dozens of kilometers to hundreds of kilometers, the situation of multiple faults or multiple types of faults occurring in the cable line is not uncommon, seriously affecting the safe operation of the cable, and also making the commonly used cable fault detection methods on land (such as time domain reflectometry, frequency domain detection method, ultrasonic detection method, infrared detection method, and partial discharge method, etc.) unable to be well applied. Therefore, it is necessary to conduct research on the problem of multi-source fault detection and identification, and propose a technical method that can safely, reliably and efficiently carry out multi-source fault detection and identification of DC power supply cables in a submarine observation network. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for multi-source fault detection and identification of DC power supply cables in a submarine observation network.

[0005] The technical solution for achieving the purpose of the present invention is as follows:

[0006] A method for detecting and identifying multi-source faults in DC power supply cables of a submarine observation network, which is used to detect and identify multi-source faults in the power supply cables of a submarine observation network. The method is characterized by the following steps:

[0007] Step 1: Connection of the multi-source fault detection circuit for the cables of the submarine observation network

[0008] The connection circuit for detecting and identifying multi-source faults in the DC power supply cables of the submarine observation network consists of a DC high-voltage isolation capacitor (4), an isolation transformer (5), a sealed housing (6), a transmitted signal output port (7), a reflected signal input port (8), a mutual similarity comparison module (9), a calculation result output terminal (10), a control terminal (11), a transmitted signal generator 5 (12), a transmitted signal generator 4 (13), a transmission frequency selector (14), a control signal input terminal (15), a selector output terminal (16), a transmitted signal generator 3 (17), a transmitted signal generator 2 (18), a transmitted signal generator 1 (19), and a signal amplifier (20). Before testing, the lead-out wire of the DC high-voltage isolation capacitor (4) needs to be connected to the cable line to be tested. The cable line to be tested includes a positive line high-voltage terminal (1), a negative line high-voltage terminal (2), and an optical and electrical composite cable terminal (3), and the connection can be made according to the test requirements;

[0009] Step 2: Detection of the DC power supply cable and data acquisition

[0010] 2.1 After Step 1 is completed, connect the test instrument tightly to the metal end of the DC power supply cable through the DC high-voltage isolation capacitor (4). The cable needs to be powered off during the connection process of the test instrument, and after the connection is completed, select to perform the test while the cable is powered on;

[0011] 2.2 Modulate a high-frequency test signal s(t) using the spread spectrum time domain reflection technology and output it from the transmitted signal output port (7). The frequencies of the modulated test signals f x are 50 kHz, 500 kHz, 10 MHz, 30 MHz, and 200 MHz in sequence, and can be modulated and generated by the transmitted signal generator 1 (19), the transmitted signal generator 2 (18), the transmitted signal generator 3 (17), the transmitted signal generator 4 (13), and the transmitted signal generator 5 (12) in sequence; where x = 1, 2, 3, 4, 5; and the modulated high-frequency test signals are represented as s x (t), x = 1, 2, 3, 4, 5;

[0012] 2.3 Use the high-frequency test signal s(t) in step (2.2) to perform a traveling wave test. The test signal frequencies are in the order from low to high, and the corresponding reflected wave information is collected successively through the DC high-voltage isolation capacitor (4), the isolation transformer (5), and the reflected signal input port (8), with R x(t), where x = 1, 2, 3, 4, 5 is used for representation;

[0013] 2.4 Perform preliminary processing on the collected reflected signal R x (t) as follows

[0014]

[0015] Step 3: Establish a long-distance power transmission cable fault model

[0016] According to the relationship between the transmitted signal s x (t) and the reflected signal r x (t), establish an underwater long-distance power transmission cable damage model:

[0017] 3.1 Perform mixed signal isolation processing on the reflected signal r x (t) as follows:

[0018] re x (t) = w x *r x (t) - n x *s x (t) - l x (t) (2)

[0019]

[0020]

[0021] In the formula, w x and n x are respectively the reflected signal proportionality factor and the transmitted signal mixing coefficient, and l x is the background noise signal;

[0022] 3.2 Calculate the cross-correlation function G x (t) of the transmitted signal s x (t) and the isolated reflected signal re d (t) under different test frequency signals as follows:

[0023]

[0024] In the formula, λ is the time difference, that is, the delay time, between the first transmitted signal s x (t) and the received reflected signal r x (t) during the test. The value range of λ is [0, 63 / f x ;

[0025] 3.3 Draw the corresponding cross-correlation function curve according to the calculated cross-correlation function values, denoted as g x(λ), where x = 1, 2, 3, 4, 5, and g1(λ), g2(λ), g3(λ), g4(λ), g5(λ) correspond to the frequency signal conditions of 50 kHz, 500 kHz, 10 MHz, 30 MHz, and 200 MHz respectively; for the obtained cross-correlation function curves, find their peak points respectively, denoted as β x (λ y ), that is:

[0026]

[0027] In the formula, y is the coordinate point corresponding to different reflection time differences in the cross-correlation function curve; after calculation, compare the obtained β x (λ y ) and select the coordinate points λ that meet the following conditions y ,

[0028]

[0029] List the coordinate points that meet the conditions and name them λ x1y1 , λ x2y2 , …, λ xnyn ;

[0030] 3.4 Based on the results obtained in step 3.3, identify the number of multi-source faults in the DC power supply cable of the submarine observation network as follows:

[0031] If in the case of x = 1, there are m y coordinates that meet the above conditions, that is, λ 1y1 , λ 1y2 , …, λ 1ym , then there are m faults in the interval [1680m, 105840m] of the power supply line;

[0032] If in the case of x = 2, there are n y coordinates that meet the above conditions, that is, λ 2y1 , λ 2y2 , …, λ 2yn , then there are n faults in the interval [168m, 10584m] of the power supply line;

[0033] If in the case of x = 3, there are q y coordinates that meet the above conditions, that is, λ 3y1 , λ 3y2 , …, λ 3yq , then there are q faults in the interval [8.4m, 529m] of the power supply line;

[0034] If in the case of x = 4, there are p y coordinates that meet the above conditions, that is, λ 4y1 , λ 4y2 , …, λ 4yp, then there are p faults occurring in the range of [2.8m, 176.4m] of the power supply line;

[0035] If x = 5, there are j y - coordinates satisfying the above conditions, that is, λ 5y1 , λ 5y2 , …, λ 5yj , then there are j faults occurring in the range of [0.084m, 5.29m] of the power supply line.

[0036] Furthermore, it also includes the following steps:

[0037] The described method for detecting and identifying multi - source faults of a DC - powered cable in a submarine observation network is pre - buried during the laying of the power supply system of the submarine observation network, realizing long - term underwater online fault detection and identification, and is more suitable for the requirements of long - standby, concealment and reliability of the submarine observation network, improving the practical application value of this method.

[0038] The beneficial effects of the present invention are as follows:

[0039] The method for detecting and identifying multi - source faults of a DC - powered cable in a submarine observation network of the present invention can accurately, safely, real - time and efficiently detect and identify various types of faults and multi - point faults of the DC - powered cable, providing scientific and reliable data for the maintenance and repair of the energy supply network of the submarine observation network, and realizing its long - term reliable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is the detection principle diagram of the technology for detecting and identifying multi - source faults of a DC - powered cable in a submarine observation network of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The following further explains the present invention with reference to the drawings.

[0042] Figure 1 is the detection principle diagram of the technology for detecting and identifying multi - source faults of a DC - powered cable in a submarine observation network of the present invention, used to achieve the purpose of detecting and identifying multi - source faults of the power supply cable of the submarine observation network. Its structure and usage method include the following content:

[0043] The first step: Connection of the multi - source fault detection circuit of the submarine observation network cable

[0044] The connection circuit for multi-source fault detection and identification of a submarine observation network DC power supply cable consists of a DC high-voltage isolation capacitor (4), an isolation transformer (5), a sealed housing (6), a transmitted signal output port (7), a reflected signal input port (8), a mutual similarity comparison module (9), a calculation result output terminal (10), a control terminal (11), a transmitted signal generator 5 (12), a transmitted signal generator 4 (13), a transmission frequency selector (14), a control signal input terminal (15), a selector output terminal (16), a transmitted signal generator 3 (17), a transmitted signal generator 2 (18), a transmitted signal generator 1 (19), and a signal amplifier (20). Before testing, the lead wire of the DC high-voltage isolation capacitor (4) needs to be connected to the cable line to be tested. The cable line to be tested includes a positive line high-voltage end (1), a negative line high-voltage end (2), and an optical and electrical composite cable end (3), which can be connected according to the test requirements;

[0045] Step 2: Detection and data acquisition of the DC power supply cable

[0046] 2.1 After the first step is completed, connect the test instrument tightly to the metal end of the DC power supply cable through the DC high-voltage isolation capacitor (4). The cable needs to be powered off during the connection process of the test instrument, and after the connection is completed, select live testing;

[0047] 2.2 Modulate a high-frequency test signal s(t) using the extended spectrum time-domain reflection technology and output it from the transmitted signal output port (7). The frequencies of the modulated test signals f x are 50 kHz, 500 kHz, 10 MHz, 30 MHz, and 200 MHz in sequence, and can be modulated and generated by the transmitted signal generator 1 (19), the transmitted signal generator 2 (18), the transmitted signal generator 3 (17), the transmitted signal generator 4 (13), and the transmitted signal generator 5 (12) in sequence; where x = 1, 2, 3, 4, 5; and represent the modulated high-frequency test signals as s x (t), x = 1, 2, 3, 4, 5;

[0048] 2.3 Conduct a traveling wave test using the high-frequency test signal s(t) in 2.2. The test signal frequencies are in ascending order and collect the corresponding reflected wave information through the DC high-voltage isolation capacitor (4), the isolation transformer (5), and the reflected signal input port (8) in sequence, and represent it as R x (t), x = 1, 2, 3, 4, 5;

[0049] 2.4 Conduct preliminary processing on the collected reflected signal R x (t) as follows

[0050]

[0051] Step 3: Establishment of Long-distance Power Transmission Cable Fault Model

[0052] Based on the relationship between the transmitted signal s x (t) and the reflected signal r x (t) at different test frequencies, establish an underwater long-distance power transmission cable damage model:

[0053] 3.1 Isolate the mixed signals of the reflected signal r x (t) as follows:

[0054] re x (t) = w x *r x (t) - n x *s x (t) - l x (t) (2)

[0055]

[0056] In the formula, w x and n x are the reflection signal proportionality factor and the transmitted signal mixing coefficient respectively, and l x is the background noise signal;

[0057] 3.2 Calculate the cross-correlation function G x (t) of the transmitted signal s x (t) and the isolated reflected signal re d (t) under different test frequency signals as follows:

[0058]

[0059] In the formula, λ is the time difference between the first transmitted signal s x (t) and the received reflected signal r x (t) during the test, that is, the delay time. The value range of λ is [0, 63 / f x ;

[0060] 3.3 Draw the corresponding cross-correlation function curve according to the calculated cross-correlation function values, denoted as g x (λ), where x = 1, 2, 3, 4, 5. Among them, g1(λ), g2(λ), g3(λ), g4(λ), g5(λ) correspond to the frequency signal conditions of 50 kHz, 500 kHz, 10 MHz, 30 MHz, and 200 MHz respectively; find the peak points of the obtained cross-correlation function curves respectively, denoted as β x (λ y ), that is:

[0061]

[0062] Where y is the coordinate point corresponding to the different reflection time differences in the mutual similarity function curve; after calculation, the obtained β x (λ y ) are compared, and the coordinate points λ that meet the following conditions are selected y ,

[0063]

[0064] The coordinate points that meet the conditions are listed and named λ x1y1 , λ x2y2 , …, λ xnyn ;

[0065] 3.4 Based on the results obtained in step 3.3, identify the number of multi-source faults in the DC power supply cable of the submarine observation network as follows:

[0066] If x = 1, there are m y coordinates that meet the above conditions, namely λ 1y1 , λ 1y2 , …, λ 1ym , then there are m faults in the [1680m, 105840m] interval of the power supply line;

[0067] If x = 2, there are n y coordinates that meet the above conditions, namely λ 2y1 , λ 2y2 , …, λ 2yn , then there are n faults in the [168m, 10584m] interval of the power supply line;

[0068] If x = 3, there are q y coordinates that meet the above conditions, namely λ 3y1 , λ 3y2 , …, λ 3yq , then there are q faults in the [8.4m, 529m] interval of the power supply line;

[0069] If x = 4, there are p y coordinates that meet the above conditions, namely λ 4y1 , λ 4y2 , …, λ 4yp , then there are p faults in the [2.8m, 176.4m] interval of the power supply line;

[0070] If x = 5, there are j y coordinates that meet the above conditions, namely λ 5y1 , λ 5y2 , …, λ 5yj , then there are j faults in the [0.084m, 5.29m] interval of the power supply line.

[0071] In addition, the present invention can also implement the following test functions:

[0072] The described method for detecting and identifying multi-source faults of a DC power supply cable for a submarine observation network is pre-buried during the laying of the power supply system of the submarine observation network, realizing long-term underwater online fault detection and identification, and is more suitable for the requirements of long standby, concealment and reliability of the submarine observation network, improving the practical application value of this method.

Claims

1. A method for detecting and identifying multi-source faults in DC power supply cables of a submarine observation network, which is used to detect and identify multi-source faults in power supply cables of a submarine observation network, characterized in that: The steps include: Step 1: Connecting the multi-source fault detection loop of the submarine observation network cable The connection circuit for multi-source fault detection and identification of DC power supply cables of a submarine observation network mainly comprises a DC high-voltage isolation capacitor (4), an isolation transformer (5), a sealed housing (6), a transmission signal output port (7), a reflection signal input port (8), a mutual similarity comparison module (9), a calculation result output port (10), a control terminal (11), a transmission signal generator 5 (12), a transmission signal generator 4 (13), a transmission frequency selector (14), a control signal input port (15), a selector output port (16), a transmission signal generator 3 (17), a transmission signal generator 2 (18), a transmission signal generator 1 (19), and a signal amplifier (20). Before testing, the lead wire of the DC high-voltage isolation capacitor (4) needs to be connected to the cable line to be tested. The cable line to be tested includes a positive line high-voltage terminal (1), a negative line high-voltage terminal (2), and an optoelectronic composite cable terminal (3), which can be connected according to test requirements. Step 2: DC power supply cable detection and data acquisition 2.1 After the first step is completed, the test instrument is tightly connected to the metal end of the DC power supply cable through the DC high-voltage isolation capacitor (4). The cable must be powered off during the connection process. After the connection is completed, select the live test; 2.2 Using the spread spectrum time domain reflectometry technique, a high-frequency test signal s(t) is modulated and output from the transmit signal output port (7). The modulated test signal frequency f x 50kHz, 500kHz, 10MHz, 30MHz, 200MHz, respectively, which can be modulated and generated by transmitting signal generator 1 (19), transmitting signal generator 2 (18), transmitting signal generator 3 (17), transmitting signal generator 4 (13), transmitting signal generator 5 (12) in sequence; wherein, x = 1, 2, 3, 4, 5; and The modulated high frequency test signal is x (t), x=1,2,3,4,5 to represent; 2.3 Use the high-frequency test signal s(t) in 2.2 to perform traveling wave test. The test signal frequency is in the order from low to high, and the corresponding reflected wave information is collected in sequence through the DC high-voltage isolation capacitor (4), isolation transformer (5) and reflection signal input port (8). x (t), x=1,2,3,4,5 for representation; 2.4 The collected reflection signal R x (t) Perform preliminary processing as follows Step 3: Establishing a long-distance transmission cable fault model According to the different test frequencies, the signal s is transmitted x (t) and the reflected signal r x (t), and establish a damage model for underwater long-distance transmission cables: 3.1 Pair of reflected signals r x (t) Perform mixed signal isolation processing as follows: re x (t)=w x *r x (t)-n x *s x (t)-l x (t) (2) Where w x 、n x are respectively the reflection signal proportional factor and the transmission signal mixing coefficient, l x is the background noise signal; 3.2 Calculate the transmitted signal s under different test frequency signals respectively x (t) and the reflected signal re after isolation x The mutual similarity function G of (t) d (t), as shown below: Where λ is the first transmitted signal s during the test process x (t) and the received reflected signal r x The time difference between (t), that is, the delay time, the value range of λ is [0,63 / f x ]; 3.3 According to the calculated mutual similarity function value, draw the corresponding mutual similarity function curve, denoted as g x (λ), x=1,2,3,4,5, where g1(λ), g2(λ), g3(λ), g4(λ), g5(λ) correspond to the frequency signal conditions of 50kHz, 500kHz, 10MHz, 30MHz, and 200MHz respectively; the peak value of the obtained mutual similarity function curve is calculated and recorded as β x (λ y ),Right now: Where y is the coordinate point corresponding to the different reflection time differences in the mutual similarity function curve; after calculation, the obtained β x (λ y ) to compare and select the coordinate point λ that meets the following conditions y , List the coordinate points that meet the conditions and name them λ in sequence x1y1 ,λ x2y2 ,…,λ xnyn ; 3.4 Based on the results obtained in step 3.3, the number of multi-source faults in the DC power supply cables of the submarine observation network is identified as follows: If x=1, there are m y coordinates that meet the above conditions, that is, λ 1y1 ,λ 1y2 ,…,λ 1ym , then there are m faults in the interval [1680m,105840m] of the power supply line; If x=2, there are n y coordinates that meet the above conditions, that is, λ 2y1 ,λ 2y2 ,…,λ 2yn , then there are n faults in the interval [168m,10584m] of the power supply line; If x=3, there are q y coordinates that meet the above conditions, that is, λ 3y1 ,λ 3y2 ,…,λ 3yq , then there are q faults in the interval [8.4m,529m] of the power supply line; If x=4, there are p y coordinates that meet the above conditions, that is, λ 4y1 ,λ 4y2 ,…,λ 4yp , then there are p faults in the interval [2.8m,176.4m] of the power supply line; If x=5, there are j y coordinates that meet the above conditions, that is, λ 5y1 ,λ 5y2 ,…,λ 5yj , there are j faults in the interval [0.084m,5.29m] of the power supply line.

2. The multi-source fault detection and identification method for a DC power supply cable in a submarine observation network as described in claim 1 is pre-buried during the installation of the submarine observation network power supply system, enabling long-term underwater online fault detection and identification. This method is more suitable for the long standby, concealment, and reliability requirements of the submarine observation network, thereby improving the practical application value of the method.

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