Intelligent monitoring device and protection method for negative ground one-way conduction device

Abstract

The invention relates to the field of intelligent monitoring, in particular to an intelligent monitoring device for a negative ground one-way conduction device and a protection method, and the intelligent monitoring device comprises a control unit, an analog quantity detection unit, a display unit, a storage unit, a communication unit and a relay output unit. The invention further provides a protection method of the intelligent monitoring device for the negative ground one-way conduction device, the fault circuit can be cut off when a contact network is in a grounding short circuit fault, the operation state of the negative ground one-way conduction device can be detected in real time, and when the negative ground one-way conduction device breaks down, the device is protected. And the negative ground one-way conduction device operates in an optimal state, so that the stability and safety of a power supply system are ensured.

Description

Technical Field

[0001] The present invention relates to the field of intelligent monitoring, and in particular to an intelligent monitoring device and a protection method for a negative-to-ground unidirectional conduction device. Background Art

[0002] At present, most urban rail transit projects in China use a DC traction power supply system. DC power is transmitted to the traction locomotive through the overhead contact network or contact rail. The traction locomotive drags the train forward and returns the traction current to the substation through the running rail. The return system of the urban rail line is distributed over a wide area, and it is difficult to ensure that the rail-to-ground insulation at all locations is in good condition. It is easy for local insulation to be weak or damaged, generating stray current. The leaked stray current causes serious electrochemical corrosion to the steel bars of tunnel structures, urban buried pipelines, and building structure steel bars, posing a huge safety hazard.

[0003] In order to fundamentally solve the leakage and harm of stray current, some urban rail transit lines have adopted dedicated rail return power supply systems, and there are various systems such as magnetic levitation, rubber-wheeled four-track, straddle-type monorail, etc. In order to ensure that the fault circuit is cut off when the positive pole of the traction network is short-circuited to the ground, a negative ground unidirectional conduction device is set between the grounding grid and the dedicated return rail to provide a return path for the fault current.

[0004] The existing negative-ground unidirectional conduction device can monitor the operating status and leakage status of the power supply system, but the design of the negative-ground unidirectional conduction device's own protection is not given enough attention. As an important part of the dedicated rail return power supply system, the negative-ground unidirectional conduction device's own fault detection and alarm should not be ignored. Summary of the invention

[0005] Purpose of the invention: To provide an intelligent monitoring device for a negative-ground one-way conductive device, and further provide a protection method based on the above-mentioned intelligent monitoring device for a negative-ground one-way conductive device, so as to solve the above-mentioned problems existing in the prior art.

[0006] Technical solution: An intelligent monitoring device for a negative-ground one-way conduction device includes six components: a control unit, an analog detection unit, a display unit, a storage unit, a communication unit and a relay output unit.

[0007] The control unit is used for communication between the module units and can analyze and judge the received current and voltage data;

[0008] The analog detection unit is connected to the control unit and is used to detect the current value flowing through each branch and transmit the corresponding data to the control unit;

[0009] The display unit is connected to the control unit and is used to display corresponding status information, set device alarm parameters, and query historical information;

[0010] The storage unit is connected to the control unit and is used for data storage and time recording;

[0011] The communication unit is connected to the control unit and is connected to the integrated automation background communication, uploading the current, voltage, alarm information, isolation switch status, etc. to the integrated automation background, and accepting the isolation switch opening and closing action command issued by the integrated automation background;

[0012] The relay output unit is connected to the control unit, and is divided into relay output unit 1 and relay output unit 2, and is connected to the negative ground one-way conduction device isolating switch, and can output the corresponding opening and closing action instructions of the control unit.

[0013] In a further embodiment, the analog detection unit is connected to multiple current sensors. The control unit analyzes the received current and voltage data and makes corresponding judgments to implement short circuit alarm, open circuit alarm, uneven current alarm, sensor fault alarm, main circuit current protection, and issue an alarm when it is determined to be a fault.

[0014] A protection method for an intelligent monitoring device for a negative-ground one-way conduction device, characterized in that:

[0015] Through the autonomous analysis of the data of the control unit, it is possible to determine and autonomously issue a short circuit alarm, an open circuit alarm, an uneven current alarm, a sensor fault alarm, and a main circuit current protection for the negative-to-ground unidirectional conduction device branch.

[0016] In a further embodiment, when the short-circuit alarm is activated, the branch current has a reverse current that is greater than the reverse current limit value, or the total forward current is greater than the starting short-circuit alarm threshold. If the current percentage of a branch is greater than the percentage setting value, it is judged that the diode branch is short-circuited and a short-circuit warning is issued.

[0017] In a further embodiment, when the open circuit alarm is activated and the total forward current reaches the threshold for starting the open circuit alarm, if the current percentage of a branch is less than the percentage limit, it is determined that the branch is open and an open circuit alarm is issued.

[0018] In a further embodiment, the control unit calculates the sum of the currents of each branch and compares it with the total current detected by the main circuit. If the difference between the two exceeds a set value, it is determined that there is a sensor failure and an alarm is issued.

[0019] In a further embodiment, when the uneven current alarm is activated, there is no short circuit alarm, open circuit alarm or sensor fault prompt, and the current of each branch is a forward current. When one or more branch currents are less than the product of the branch current average value and the set current sharing coefficient, an uneven current alarm is issued.

[0020] In a further embodiment, the main circuit current protection is divided into two-stage protection modes, namely, one-stage current warning and two-stage current protection.

[0021] In a further embodiment, when the first-stage current alarm is activated and there is no sensor failure, the total current of the main circuit is continuously greater than the first-stage current setting value within a fixed time, and a first-stage current alarm is issued; when the second-stage current protection is activated and there is no sensor failure, the total current of the main circuit is continuously greater than the second-stage current protection setting value within a fixed time, and the control unit controls the relay output unit to operate, thereby triggering the contact network feeder cabinet circuit breaker to trip and cut off the faulty circuit.

[0022] Beneficial effects: The present invention relates to an intelligent monitoring device and protection method for a negative-to-ground unidirectional conduction device, which relates to the field of intelligent monitoring and includes six components: a control unit, an analog detection unit, a display unit, a storage unit, a communication unit, and a relay output unit. A protection method for an intelligent monitoring device for a negative-to-ground unidirectional conduction device is further proposed, which can realize the cutting off of the fault circuit when the contact network is short-circuited to the ground, and can detect the operating state of the negative-to-ground unidirectional conduction device in real time. When the negative-to-ground unidirectional conduction device fails, the device is protected, so that the negative-to-ground unidirectional conduction device operates in the best state to ensure the stability and safety of the power supply system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the connections between the various units of the intelligent monitoring device for a negative ground one-way conduction device according to the present invention.

[0024] Figure 2 It is a short circuit alarm logic diagram of the intelligent monitoring device in an embodiment of the present invention.

[0025] Figure 3 It is a logic diagram of an open circuit alarm of an intelligent monitoring device in an embodiment of the present invention.

[0026] Figure 4 It is a sensor fault alarm logic diagram of the intelligent monitoring device in an embodiment of the present invention.

[0027] Figure 5 It is a logic diagram of uneven current alarm of the intelligent monitoring device in an embodiment of the present invention.

[0028] Figure 6 It is a main circuit current protection logic diagram of the intelligent monitoring device in an embodiment of the present invention.

[0029] Reference numerals: control unit 11, analog detection unit 12, display unit 13, storage unit 14, communication unit 15, relay output unit 20, relay output unit 1 21, relay output unit 2 22 DETAILED DESCRIPTION

[0030] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0031] The applicant believes that the existing negative-to-ground one-way conduction device can monitor the operating status and leakage status of the power supply system, but does not pay enough attention to the design of the protection of the negative-to-ground one-way conduction device itself.

[0032] To this end, the applicant has designed an intelligent monitoring device and protection method for a negative-ground unidirectional conduction device, which can cut off the faulty circuit when a contact network grounding short circuit occurs, and can detect the operating status of the negative-ground unidirectional conduction device in real time. When a fault occurs in the negative-ground unidirectional conduction device, the device can be protected to enable the negative-ground unidirectional conduction device to operate in the best state to ensure the stability and safety of the power supply system.

[0033] The intelligent monitoring device for a negative-ground one-way conducting device according to the present invention mainly comprises six components: a control unit, an analog detection unit, a display unit, a storage unit, a communication unit and a relay output unit.

[0034] The control unit is used for communication between the module units and can analyze and judge the received current and voltage data.

[0035] The analog detection unit is connected to the control unit and is used to detect the current value flowing through each branch and transmit the corresponding data to the control unit.

[0036] The display unit is connected to the control unit and is used to display corresponding status information, set device alarm parameters, and query historical information.

[0037] The storage unit is connected to the control unit and is used for data storage and time recording.

[0038] The communication unit is connected to the control unit and to the integrated automation background communication, uploads the current, voltage, alarm information, isolation switch status, etc. to the integrated automation background, and accepts the isolation switch opening and closing action commands issued by the integrated automation background.

[0039] The relay output unit is connected to the control unit, and is divided into relay output unit 1 and relay output unit 2, and is connected to the negative ground one-way conduction device isolating switch, and can output the corresponding opening and closing action instructions of the control unit.

[0040] The analog detection unit is connected to multiple current sensors. The control unit analyzes the received current and voltage data and makes corresponding judgments to implement short circuit alarm, open circuit alarm, uneven current alarm, sensor fault alarm, main circuit current protection, and issue an alarm when it is determined to be a fault.

[0041] Based on the above-mentioned intelligent monitoring device for negative-ground one-way conduction device, the present invention proposes a protection method for the intelligent monitoring device for negative-ground one-way conduction device, which is characterized by:

[0042] Through the autonomous analysis of the data of the control unit, it is possible to determine and autonomously issue a short circuit alarm, an open circuit alarm, an uneven current alarm, a sensor fault alarm, and a main circuit current protection for the negative-to-ground unidirectional conduction device branch.

[0043] When the short-circuit alarm is activated, the branch current has a reverse current that is greater than the reverse current limit value, or the total forward current is greater than the starting short-circuit alarm threshold. If the current percentage of a branch is greater than the percentage setting value, it is judged that the diode branch is short-circuited and a short-circuit warning is issued.

[0044] When the open circuit alarm is activated, the total forward current reaches the threshold to start the open circuit alarm. If the current percentage of a branch is less than the percentage limit, the branch is judged to be open and an open circuit alarm is issued.

[0045] The control unit calculates the sum of the currents of each branch and compares it with the total current detected by the main circuit. If the difference between the two exceeds a set value, it is determined that there is a sensor failure and an alarm is issued.

[0046] When the uneven current alarm is activated, there is no short circuit alarm, open circuit alarm or sensor fault prompt, and the current of each branch is a positive current. When the current of one or more branches is less than the product of the average branch current and the set current sharing coefficient, an uneven current alarm is issued.

[0047] The main circuit current protection is divided into two-stage protection modes, namely, one-stage current warning and two-stage current protection.

[0048] When the first-stage current alarm is activated and there is no sensor failure, the total current of the main circuit continues to be greater than the first-stage current setting value within a fixed time, and a first-stage current alarm is issued; when the second-stage current protection is activated and there is no sensor failure, the total current of the main circuit continues to be greater than the second-stage current protection setting value within a fixed time, and the control unit controls the relay output unit to operate, linking the contact network feeder cabinet circuit breaker to trip, and cut off the faulty circuit.

[0049] In a further preferred embodiment, Figure 1It is a module schematic diagram of an intelligent monitoring device for a negative-ground one-way conduction device provided in an embodiment of the present invention, which includes: a control unit 11, an analog detection unit 12, a display unit 13, a storage unit 14, a communication unit 15, and a relay output unit 20.

[0050] The relay output unit 20 includes a relay output unit 1 21 and a relay output unit 22 .

[0051] The analog detection unit 12 , the display unit 13 , the storage unit 14 , the communication unit 15 , the relay output unit 1 21 and the relay output unit 2 22 are respectively connected to the control unit 11 .

[0052] The negative ground unidirectional conduction device is provided with 4 diode branches, and the main circuit and each branch are provided with 5 current sensors, each sensor is connected to the analog detection unit 12 of the intelligent monitoring device, and the analog detection unit 12 is used to detect the voltage value of the negative ground unidirectional conduction device and the current value flowing through each branch, and the detected current and voltage values ​​are used as the basis for judging the operating state of the negative ground unidirectional conduction device and transmitted to the control unit 11;

[0053] The control unit 11 analyzes and judges the received current and voltage data, realizes short circuit alarm, open circuit alarm, uneven current alarm, sensor fault alarm, main circuit current protection, and issues an alarm when it is determined to be a fault. When the main circuit current is greater than the set value, the control unit 11 controls the relay output unit 1 21 to control the contact network feeder cabinet circuit breaker to trip and cut off the fault circuit. The intelligent monitoring device also controls the disconnection and closing action of the negative ground one-way conduction device isolation switch through the relay output unit 2 22.

[0054] The communication unit 15 realizes the communication between the intelligent monitoring device and the integrated automation background, uploads the status information of the negative-to-ground unidirectional conduction device: current, voltage, alarm information, disconnector status, etc. to the integrated automation background, and receives the disconnector opening and closing action commands issued by the integrated automation background.

[0055] The display unit 13 is used to display the status information of the negative-to-ground unidirectional conduction device, to set the device alarm parameters, and to query historical information, such as historical data, curves and alarm events.

[0056] The storage unit 14 is used for data storage and event recording to facilitate later data analysis.

[0057] Negative ground one-way conduction device alarm judgment method:

[0058] The intelligent monitoring device can determine and issue short-circuit alarms, open-circuit alarms, uneven current alarms, sensor failure alarms, and main circuit current protection for the negative-ground unidirectional conduction device branch.

[0059] (1) Figure 2The short circuit alarm logic diagram of the intelligent monitoring device provided by the embodiment of the present invention is as follows: i Less than 0 and greater than the reverse current limit value I 设 A short circuit alarm is issued when the reverse current is less than the limit value I 设 The short circuit alarm is canceled when the branch current I i Greater than 0, and the total branch current I 总 Greater than the total current setting value I 总设定 , when there is one or more branches with a current percentage of i Ratio greater than the percentage setting value a 设i A short circuit alarm is issued when the total branch current I 总 Less than the total current setting value I 总设定 Or the branch current percentage a i All are less than the percentage setting value a 设i Cancel the short circuit alarm.

[0060] I 总 =I1+I2+...+I n (n≤4)

[0061]

[0062] Where is the sum of the currents in each branch;

[0063] a i Is the current percentage I 总 Compare;

[0064] n is the number of diode branches of the negative ground unidirectional conduction device;

[0065] The specific value of the setting value is determined according to actual needs, and the reverse current limit value I 设 The setting range is -10~-40A, and the total current setting value is I 总设定 The setting range is 100~500A, the percentage setting value is a 设i The setting range is 95% to 100%.

[0066] (2) Figure 3 This is the open circuit alarm logic diagram of the intelligent monitoring device provided by the embodiment of the present invention. The open circuit alarm is activated when the total branch current I 总 Greater than the total current setting value I 总设定 , at the same time there is one or more branches with a current percentage of i Less than the percentage limit a 设2 When an open circuit alarm is issued, the total branch current I 总 Less than the total current setting value I 总设定 Or the branch current percentage a i Both are greater than the percentage limit a 设2Cancel the open circuit alarm.

[0067] The specific value of the setting value is determined according to actual needs. The total current setting value I 总设定 The setting range is 100~500A, the percentage setting value is a 设2 The setting range is 0% to 5%.

[0068] (3) Figure 4 This is a sensor fault alarm logic diagram of the intelligent monitoring device provided by the embodiment of the present invention. The sensor fault alarm is activated and the total current of each branch I is calculated. 总 , and compared with the total current I detected in the main circuit. If the absolute value of the difference between the two exceeds the set value D, a sensor fault alarm is issued. When the absolute value of the difference between the two is less than the set value D, the sensor fault alarm is cancelled.

[0069] D=|I 总 -I|

[0070] Where I is the main circuit to detect the total current;

[0071] The specific value of the set value is determined according to actual needs, and the setting range of the difference set value D is 50 to 100.

[0072] (4) Figure 5 This is the logic diagram of the uneven current alarm of the intelligent monitoring device provided by the embodiment of the present invention. When the uneven current alarm is activated and there is no short circuit alarm, open circuit alarm or sensor failure alarm, the current I i Greater than 0, when there is one or more branch currents I i Less than the average branch current I 平均 When the product of the current sharing coefficient KP is equal to the current sharing coefficient KP, an uneven current alarm is issued, and there is a short circuit alarm, an open circuit alarm, a sensor fault alarm, or a branch current I i Both are greater than the average branch current I 平均 When the current is equal to the product of the set current sharing coefficient KP, the uneven current alarm is cancelled.

[0073] I 平均 =I 总 / n

[0074] The specific value of the set value is determined according to actual needs, and the setting range of the current sharing coefficient KP is 0.85~0.95.

[0075] (5) Figure 6 It is a main circuit current protection logic diagram of an intelligent monitoring device provided by an embodiment of the present invention. The main circuit current protection is divided into two-stage protection modes: one-stage current alarm and two-stage current protection.

[0076] ① A current alarm is activated. When there is no sensor failure, the total current I of the main circuit is continuously greater than the current setting value I of a section within the set time T1.一段 , a current alarm is issued, the total current I of the main circuit is less than the current setting value I 一段 , cancel a section of current alarm;

[0077] ② When the second-stage current protection is activated and there is no sensor failure, when the total current I of the main circuit is continuously greater than the second-stage current protection setting value I within the set time T2 二段 , the control unit 11 controls the relay output unit 21 to close, the contact network feeder cabinet circuit breaker is tripped, the fault circuit is cut off, and the second-stage current protection alarm is issued at the same time. The total current I of the main circuit is less than the second-stage current protection setting value I 二段 Cancel the second-stage current alarm protection and control the relay output unit 121 to disconnect.

[0078] A current setting value I 一段 , Second stage electrical protection setting value I 二段 The specific values ​​of duration T1 and duration T2 are determined according to actual needs.

[0079] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes may be made to it in form and detail without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. An intelligent monitoring device for a negative ground one-way conduction device, Its characteristics are include: The control unit is used for communication between the module units and can analyze and judge the received current and voltage data; An analog detection unit, connected to the control unit, for detecting the current value flowing through each branch and transmitting the corresponding data to the control unit; A display unit, connected to the control unit, for displaying corresponding status information, setting device alarm parameters, and querying historical information; A storage unit, connected to the control unit, for data storage and time recording; The communication unit is connected to the control unit and to the integrated automation background communication, uploads the current, voltage, alarm information, isolation switch status, etc. to the integrated automation background, and receives the isolation switch opening and closing action command issued by the integrated automation background; The relay output unit is connected to the control unit and is divided into relay output unit 1 and relay output unit 2. It is also connected to the negative ground one-way conduction device isolating switch and can output the corresponding opening and closing action instructions of the control unit.

2. An intelligent monitoring device for a negative ground one-way conduction device according to claim 1, Features: The analog detection unit is connected to a plurality of current sensors; The control unit analyzes the received current and voltage data and makes corresponding judgments to implement short circuit alarm, open circuit alarm, uneven current alarm, sensor fault alarm, main circuit current protection, and issue an alarm when a fault is determined.

3. A protection method for an intelligent monitoring device for a negative-ground one-way conduction device according to any one of claims 1 to 2, Features: Through the autonomous analysis of the data of the control unit, it is possible to determine and autonomously issue a short circuit alarm, an open circuit alarm, an uneven current alarm, a sensor fault alarm, and a main circuit current protection for the negative-to-ground unidirectional conduction device branch.

4. A protection method for an intelligent monitoring device for a negative-ground one-way conduction device according to claim 3, Features: When the short-circuit alarm is activated, the branch current has a reverse current that is greater than the reverse current limit value, or the total forward current is greater than the starting short-circuit alarm threshold. If the current percentage of a branch is greater than the percentage setting value, it is judged that the diode branch is short-circuited and a short-circuit warning is issued.

5. A protection method for an intelligent monitoring device for a negative-ground one-way conduction device according to claim 3, Features: When the open circuit alarm is activated, the total forward current reaches the threshold to start the open circuit alarm. If the current percentage of a branch is less than the percentage limit, the branch is judged to be open and an open circuit alarm is issued.

6. A protection method for an intelligent monitoring device for a negative-ground one-way conduction device according to claim 3, Features: The control unit calculates the sum of the currents of each branch and compares it with the total current detected by the main circuit. If the difference between the two exceeds a set value, it is determined that there is a sensor failure and an alarm is issued.

7. A protection method for an intelligent monitoring device for a negative-ground one-way conduction device according to claim 3, Features: When the uneven current alarm is activated, there is no short circuit alarm, open circuit alarm or sensor fault prompt, and the current of each branch is a positive current. When the current of one or more branches is less than the product of the average branch current and the set current sharing coefficient, an uneven current alarm is issued.

8. A protection method for an intelligent monitoring device for a negative-ground one-way conduction device according to claim 3, Features: The main circuit current protection is divided into two-stage protection modes, namely, one-stage current warning and two-stage current protection.

9. A protection method for an intelligent monitoring device for a negative-ground one-way conduction device according to claim 3, Features: When a section current alarm is activated and there is no sensor failure, the total current of the main circuit continues to be greater than the section current setting value within a fixed time, and a section current alarm is issued; When the second-stage current protection is activated and there is no sensor failure, the total current of the main circuit continues to be greater than the second-stage current protection setting value within a fixed time. The control unit controls the relay output unit to operate, linking the contact network feeder cabinet circuit breaker to trip and cut off the faulty circuit.

Images