Optical fiber passive high voltage cable circulating current detection system and method

Abstract

The application relates to a kind of optical fiber passive high-voltage cable circulating current detection system and method, the detection system includes circulating current detection unit, light-emitting control unit, optical fiber module, optical detection unit and circulating current calculation unit;The circulating current detection unit can gather mutual energy of high-voltage circulating current into the capacitor C of light-emitting control unit;After the optical detection unit detects the optical signal, sends pulse signal;The circulating current calculation unit has timing function, can accurately count twice pulse time;The circulating current calculation unit converts time t into current size I using formula I=U*C / t;The circulating current calculation unit supports optical fiber, Ethernet, GPRS transmission data to server;The optical detection unit detects optical signal, and calculates the time of twice light-emitting point pulse through the circulating current calculation unit, calculates the corresponding armored circulating current size.

Description

Technical Field

[0001] This invention belongs to the fields of high voltage electricity and optical fiber communication, and specifically relates to a circulating current detection system and method for optical fiber passive high voltage cables. Background Technology

[0002] In the prior art, Chinese utility model patent with announcement number CN208432655U provides a high-voltage transmission cable circulating current synchronous detection device. A metal sheath current monitor is connected to each end of the high-voltage transmission cable requiring circulating current detection. A trigger device is placed in the middle of the metal sheath current monitors, equidistant from both monitors. The trigger device simultaneously sends acquisition signals to both monitors. Since the acquisition signals originate from the same trigger device, the two monitors simultaneously acquire the circulating current values ​​at both ends of the high-voltage transmission cable, achieving strict synchronization accuracy in detecting the circulating current value of the high-voltage transmission cable.

[0003] The task of online monitoring and diagnosis of power cables is to understand the insulation status of the cables. This includes using various detection, measurement, monitoring, analysis and judgment methods, combined with the history and current status of the system, taking environmental factors into account, to assess the insulation status of the cables, determine whether they are in a normal or abnormal state, display and record the status, issue alarms for abnormal states so that operators can handle them in a timely manner, and provide information and basic data for the insulation assessment, rational use and safe operation of the equipment.

[0004] Power cables operate in complex environments, making inspection and maintenance extremely complicated and incurring significant daily maintenance costs. A product that can accurately and promptly assess the insulation status of power cables can substantially reduce the workload and expenses of daily maintenance. Furthermore, long-term operation will accumulate valuable historical data, providing power system personnel with data resources for systematic evaluation of power grid transmission lines.

[0005] Circulating current detection has always been a crucial indicator for assessing the operational status of high-voltage cables. Under normal conditions (i.e., single-point grounding), the circulating current in the cable's metallic sheath is minimal. Before a cable fault occurs, it is often manifested by multiple grounding points in the metallic sheath forming a loop with the ground, resulting in a significant increase in circulating current, which can reach over 90% of the main current in severe cases, leading to an increase in cable temperature. Real-time monitoring of the circulating current in the metallic sheath and its changes enables online monitoring of multi-point grounding faults in the metallic sheath of single-core cables. The collected current data is processed to provide alarms for abnormal cable currents and equipment status.

[0006] Traditional high-voltage cable circulating current detection devices also rely on solar energy or 220V mains power and GPRS communication. Their disadvantages include high cost, the need for regular maintenance, and the incurred cost of GPRS, as well as the inability to communicate in underground shafts. This invention patent primarily addresses the limitations of traditional technologies by utilizing electronic components to convert the magnitude of the high-voltage cable circulating current into optical pulse signals, using fiber optic communication. This achieves a passive signal detection device with numerous advantages, including low cost, maintenance-free operation, and easy installation. Summary of the Invention

[0007] The purpose of this invention is to provide a fiber optic passive high-voltage cable circulating current detection system and method to solve many difficulties in the existing technology, such as the need for external power supply for high-voltage cable circulating current detection, communication difficulties requiring GRS communication, difficulty in communication in underground wells, and high cost.

[0008] To achieve the above objectives, the present invention adopts the following technical solution.

[0009] This invention first provides a fiber optic passive high-voltage cable circulating current detection system, including a circulating current detection unit, a light-emitting control unit, an optical fiber module, a light detection unit, and a circulating current calculation unit. The circulating current detection unit focuses the mutual inductance energy of the high-voltage circulating current into the capacitor of the light-emitting control unit. The optical fiber module transmits the optical pulse signal from the light-emitting control unit to the light detection unit. The light detection unit sends a pulse signal to the circulating current calculation unit based on the detected optical signal. The circulating current calculation unit counts the time between two optical pulses and calculates the corresponding armored circulating current magnitude.

[0010] Preferably, the circulating current detection unit is made of a current transformer.

[0011] In any of the above technical solutions, it is preferred that the light-emitting control unit is connected to the circulating current detection unit, and the light-emitting control unit includes an energy-gathering device D1, a capacitor C, a voltage detector Q, a light-emitting unit D2, and a voltage detector triggering a discharge switch S. During the discharge of the capacitor C, the light-emitting unit D2 emits signal light.

[0012] In any of the above technical solutions, it is preferred that the energy-gathering device D1 is a diode, supporting full-bridge circuits and half-bridge circuits, and using a single diode.

[0013] In any of the above technical solutions, it is preferred that the capacitor C is a capacitor with a low temperature coefficient.

[0014] In any of the above technical solutions, it is preferred that the light detection unit uses a photosensitive device.

[0015] In any of the above technical solutions, it is preferred that the optical detection unit also employs a signal amplifier to enhance the detection of optical signals.

[0016] In any of the above technical solutions, it is preferred that the circulating current calculation unit includes an MCU controller, and the MCU controller is connected to a photosensitive device.

[0017] In any of the above technical solutions, it is preferred that the optical fiber module uses single-mode optical fiber.

[0018] In any of the above technical solutions, it is preferred that the optical fiber module adopts multimode optical fiber.

[0019] In any of the above technical solutions, it is preferred that the pulse signal is a falling edge pulse signal.

[0020] In any of the above technical solutions, it is preferred that the pulse signal is a rising edge pulse signal.

[0021] A method for detecting circulating current in a passive high-voltage fiber optic cable, employing a passive high-voltage fiber optic cable circulating current detection system as described in any one of claims 1 to 9, characterized by: arranging a circulating current detection unit, a light-emitting control unit, an optical fiber module, a light detection unit, and a circulating current calculation unit; the circulating current detection unit concentrates the mutual inductance energy of the high-voltage circulating current into the capacitor C of the light-emitting control unit; the optical fiber module transmits the optical pulse signal from the light-emitting control unit to the light detection unit; after detecting the optical signal, the light detection unit sends a pulse signal to the circulating current calculation unit; the circulating current calculation unit has a timing function, capable of accurately counting the time between two optical pulses; the circulating current calculation unit uses the formula I = U*C / t to convert time t into current magnitude I; the light detection unit detects the optical signal and calculates the time between two light-emitting point pulses through the circulating current calculation unit, thus calculating the corresponding armored circulating current magnitude.

[0022] In any of the above technical solutions, it is preferred that the circulating flow calculation unit supports optical fiber transmission of data to the server.

[0023] In any of the above technical solutions, it is preferred that the circulating computing unit supports Ethernet or GPRS data transmission to the server.

[0024] In any of the above technical solutions, it is preferred that the optical fiber module transmits optical pulse signals to the optical detection unit, and the circulating current calculation unit calculates the magnitude of the high-voltage cable circulating current through the time interval t of the optical pulse signals. According to the formula capacitor voltage U = Q / C, the current charges the capacitor, Q = i*t; therefore, when the capacitor C is constant and the voltage U is constant, the charge Q of the capacitor is constant, and the current i can be calculated over time t, I = Q / t = U*C / t.

[0025] The fiber optic passive high-voltage cable circulating current detection system and method of the present invention solves many difficulties in the prior art, such as the need for external power supply for high-voltage cable circulating current detection, communication difficulties requiring GRS communication, difficulties in communication in underground wells, and high cost. Compared with the prior art, the above-mentioned technical solution of the present invention has the following beneficial effects:

[0026] The fiber optic passive high-voltage cable circulating current detection system of the present invention includes a fiber optic module, supporting single-mode and multi-mode fibers. Furthermore, the optical signal of the detection unit is strong enough to ensure long-distance communication in any fiber.

[0027] The optical fiber passive high-voltage cable circulating current detection system of the present invention includes an optical detection unit and a circulating current calculation module. The optical detection unit uses an amplifier and a comparator to detect the optical signal, and uses a timer to calculate the time between two emission point pulses, thereby calculating the corresponding armor circulating current. The detection method is simple and the performance is stable.

[0028] The optical fiber passive high-voltage cable circulating current detection system and method of the present invention adopts a circulating current calculation module, which supports data transmission to the server via optical fiber, Ethernet, and GPRS. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of a preferred embodiment of the optical fiber passive high-voltage cable circulating current detection system according to the present invention.

[0031] Figure 2 This is a schematic diagram of the circulating current detection unit structure of a preferred embodiment of the optical fiber passive high-voltage cable circulating current detection system according to the present invention;

[0032] Figure 3 This is a schematic diagram of the light-emitting control unit of a preferred embodiment of the optical fiber passive high-voltage cable circulating current detection system according to the present invention;

[0033] Figure 4 This is a schematic diagram of the optical detection unit and the circulating current calculation unit according to a preferred embodiment of the optical fiber passive high-voltage cable circulating current detection system of the present invention;

[0034] Figure 5 This is a pulse signal diagram of the optical detection unit according to a preferred embodiment of the optical fiber passive high-voltage cable circulating current detection system of the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] To overcome the technical deficiencies of existing high-voltage cable circulating current detection technologies, this invention proposes a fiber optic passive high-voltage cable circulating current detection system and method. It solves numerous difficulties in existing technologies, such as the need for external power supply, communication difficulties requiring GRS communication, challenges in underground wellbore communication, and high costs. This new system ensures long-distance communication, offers a simple detection method, and provides stable performance.

[0037] The following combination Figures 1 to 5 This embodiment describes the system structure, characteristics, and implementation process of the fiber optic passive high-voltage cable circulating current detection system and method.

[0038] The optical fiber passive high-voltage cable circulating current detection system described in this embodiment includes a circulating current detection unit, a light-emitting control unit, an optical fiber module, a light detection unit, and a circulating current calculation unit. The circulating current detection unit gathers the mutual inductance energy of the high-voltage circulating current into the capacitor of the light-emitting control unit. The optical fiber module transmits the optical pulse signal from the light-emitting control unit to the light detection unit. The light detection unit sends a pulse signal to the circulating current calculation unit based on the detected optical signal. The circulating current calculation unit counts the time between two optical pulses and calculates the corresponding armored circulating current magnitude.

[0039] The circulating current detection system for passive high-voltage cables in this embodiment uses a current transformer as its circulating current detection unit.

[0040] The fiber optic passive high-voltage cable circulating current detection system of this embodiment includes a light-emitting control unit comprising an energy-gathering device D1, a capacitor C, a voltage detector Q, a light-emitting unit D2, and a voltage detector-triggered discharge switch S. During the discharge of capacitor C, the light-emitting unit D2 emits signal light. The energy-gathering device D1 is a diode, supporting full-bridge and half-bridge circuits, and uses a single diode. The capacitor C is a capacitor with a low temperature coefficient.

[0041] The optical fiber passive high-voltage cable circulating current detection system of this embodiment uses a photosensitive device in its optical detection unit.

[0042] The optical fiber passive high-voltage cable circulating current detection system of this embodiment includes a circulating current calculation unit comprising an MCU controller, which is connected to a photosensitive device.

[0043] In this embodiment of the optical fiber passive high-voltage cable circulating current detection system, the optical detection unit also employs a signal amplifier to enhance the detection of optical signals.

[0044] In this embodiment, the optical fiber passive high-voltage cable circulating current detection system uses single-mode or multi-mode optical fiber modules.

[0045] In any of the above technical solutions, it is preferred that the pulse signal is a falling edge pulse signal or a rising edge pulse signal.

[0046] A fiber optic passive high-voltage cable circulating current detection system is deployed, comprising a circulating current detection unit, a light-emitting control unit, a fiber optic module, a light detection unit, and a circulating current calculation unit. This system enables circulating current detection in the fiber optic passive high-voltage cable. The circulating current detection unit concentrates the mutual inductance energy of the high-voltage circulating current into the capacitor C of the light-emitting control unit. The fiber optic module transmits the optical pulse signal from the light-emitting control unit to the light detection unit. After detecting the optical signal, the light detection unit sends a pulse signal to the circulating current calculation unit. The circulating current calculation unit has a timing function, accurately counting the time between two optical pulses. It uses the formula I = U*C / t to convert time t into current magnitude I. The light detection unit detects the optical signal and, through the circulating current calculation unit, calculates the time between the two light-emitting pulses, thus determining the corresponding armored circulating current magnitude.

[0047] The circulating computing unit supports data transmission to the server via fiber optic, Ethernet, or GPRS.

[0048] Formula for calculating current I:

[0049] I = Q / t = U*C / t

[0050] Where t is the time interval between two light pulses, C is the capacitance value, U is the set voltage threshold for capacitor discharge, and Q is the amount of capacitor charge.

[0051] The optical fiber module transmits optical pulse signals to the optical detection unit. The circulating current calculation unit calculates the magnitude of the high-voltage cable circulating current based on the time interval t of the optical pulse signals. According to the formula, capacitor voltage U = Q / C, and current charges the capacitor, Q = i*t; therefore, when the capacitor C and voltage U are constant, the charge Q of the capacitor is constant, and the current i can be calculated over time t, I = Q / t = U*C / t.

[0052] The fiber optic passive high-voltage cable circulating current detection system and method used in this embodiment solves many difficulties in high-voltage cable circulating current detection, such as the need for external power supply, communication difficulties requiring GRS communication, difficulty in communication in underground wells, and high cost.

[0053] This embodiment supports both single-mode and multimode optical fibers. Furthermore, the optical signal from the detection unit is strong enough to ensure long-distance communication in any optical fiber.

[0054] This embodiment includes a light detection unit and a circulating current calculation module. The light detection unit uses an amplifier and a comparator to detect the light signal, and uses a timer to calculate the time between two light emission point pulses, thereby calculating the corresponding armor circulating current. The detection method is simple and the performance is stable.

[0055] This embodiment uses a circulating current calculation module, which supports data transmission to the server via fiber optic, Ethernet, and GPRS.

[0056] This embodiment uses a passive detection method to achieve high-voltage cable circulating current detection, which is convenient, fast, and low-cost.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention; the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention; any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. An optical fiber passive high voltage cable loop current detection system comprising an optical fiber module, characterized by: The detection system further comprises a circulating current detection unit, a light emitting control unit, a light detection unit and a circulating current calculation unit, the circulating current detection unit is made of a current transformer, and is used for converging mutual inductance energy of high voltage circulating current into a capacitor of the light emitting control unit, the optical fiber module transmits optical pulse signals of the light emitting control unit to the light detection unit, the light detection unit sends detected optical signals to the circulating current calculation unit, and the circulating current calculation unit counts two optical pulse times and calculates corresponding armored circulating current size. The light emitting control unit is connected with the circulating current detection unit, and comprises a device D1 for converging energy, a capacitor C, a voltage detector Q, a light emitting unit D2 and a voltage detector triggered discharge switch S, the light emitting unit D2 emits signal light during discharge of the capacitor C, the device D1 for converging energy is connected with the capacitor C in series, the light emitting unit D2 is connected with the voltage detector triggered discharge switch S in series and then is connected with the capacitor C in parallel, and the voltage detector Q is arranged at two ends of the capacitor C and is connected with the voltage detector triggered discharge switch S. The circulating current calculation unit calculates armored circulating current size by using a formula I=U*C / t, wherein I represents armored circulating current size, U represents a voltage threshold value of set capacitor discharge, C represents a capacitor value of the capacitor, and t represents a time interval of two optical pulses.

2. The fiber optic passive high voltage cable loop current detection system of claim 1, wherein: The device D1 for converging energy is a diode, supports full-bridge circuit and half-bridge circuit, and adopts a single diode.

3. The fiber optic passive high-voltage cable circulating current detection system as described in claim 1, characterized in that: The capacitor C adopts a capacitor with a low temperature coefficient.

4. The fiber optic passive high voltage cable loop current detection system of claim 1, wherein: The light detection unit adopts a photosensitive device.

5. The fiber optic passive high voltage cable loop current detection system of claim 1, wherein: The light detection unit further adopts a signal amplifier to strengthen detection of optical signals.

6. The fiber optic passive high voltage cable loop current detection system of claim 1, wherein: The pulse signal is a falling edge pulse signal.

7. The fiber optic passive high voltage cable loop current detection system of claim 1, wherein: The pulse signal is a rising edge pulse signal.

8. A method for detecting the circulating current of an optical fiber passive high voltage cable using the optical fiber passive high voltage cable circulating current detection system according to any one of claims 1 to 7, characterized in that: The circulating current detection unit, the light emitting control unit, the optical fiber module, the light detection unit and the circulating current calculation unit are arranged, the circulating current detection unit converges mutual inductance energy of high voltage circulating current into the capacitor C of the light emitting control unit, the optical fiber module transmits optical pulse signals of the light emitting control unit to the light detection unit, the light detection unit sends pulse signals to the circulating current calculation unit after detecting optical signals, the circulating current calculation unit has a timing function and can accurately count two optical pulse times, the circulating current calculation unit converts time t into current size I by using the formula I=U*C / t, the light detection unit detects optical signals and calculates time of two light emitting point pulses by the circulating current calculation unit, and armored circulating current size is calculated.

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