A system and method for preventing over-tripping of low-voltage protection for mines

Abstract

The present invention discloses a system and method for preventing over-tripping of low-voltage protection for mines, which uses a low-cost CAN bus as a communication network, self-negotiating networking, is simple, reliable and easy to maintain; the main switch equipment regularly calls the branch switch equipment information, and stops calling when a sudden fault change is detected or a locking signal is received, thereby reducing network traffic when a fault occurs and reducing bus communication conflicts; the same network realizes quick-break protection and leakage protection anti-over-tripping systems, which has universal applicability for low-voltage protection in coal mines; the transient algorithm is only used for locking signal detection and is not used as a protection exit algorithm, thereby improving the reliability of leakage protection; the main switch equipment and the branch switch equipment adopt different leakage protection action principles to ensure the ease of use and reliability of ground fault anti-over-tripping; it can realize full-line delay-free fast action of different protection types, without the need for traditional protection upper and lower level delay coordination, which has positive significance for building a safe and stable power grid.

Description

Technical Field

[0001] The present invention belongs to the technical field of power systems, and in particular relates to a system and method for preventing over-tripping of low-voltage protection for mines. Background Art

[0002] The anti-over-tripping system is a system in which the upper and lower protection levels interact with each other through information. When a fault occurs within the range of the lower protection level, the lower protection level will lock the upper protection level for a short time, and the upper protection level will not over-trip, thereby ensuring the selectivity of the protection action without sacrificing the speed of the upper protection action.

[0003] The anti-overtripping system is a combination of traditional current protection and communication technology. It is established based on a comprehensive analysis of factors such as current, time, and network interoperability. By utilizing information interaction on the communication network and the collaboration of protection devices in the area, the protection system can quickly locate and remove fault points, reduce the scope of power outages, and resolve the contradiction between the speed and selectivity of relay protection. It has positive significance for improving the safety and reliability of coal mine power supply systems.

[0004] With the advancement of smart mine construction, coal mine 10kV power supply networks are generally equipped with over-voltage protection systems. Current over-voltage protection solutions rely on dedicated fiber optic or Ethernet communications, requiring dedicated communication servers or switches. This leads to high construction costs and complex configuration. The 1140 / 660V low-voltage power supply network has a simple topology, lacks a dedicated communication network, and is costly, making it unsuitable for current over-voltage protection solutions. Summary of the Invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide a system and method for preventing over-tripping of low-voltage protection for mines, which uses a low-cost CAN bus communication network and self-negotiation networking, is simple and reliable, and ensures the selectivity of protection action without sacrificing the rapidity of the upper protection action, thereby realizing the rapid positioning and reliable isolation function of quick-break protection and leakage protection.

[0006] To achieve the above-mentioned objectives, the present invention provides a system for low-voltage protection and anti-over-tripping for mines, the system comprising a main switch device, multiple branch switch devices, a CAN bus communication network, and terminal resistors. The main switch device realizes main power supply line fault detection and removal and network topology management, the branch switch device realizes branch power supply line fault detection and removal, the CAN bus communication network is used for information transmission of the switch device, and the terminal resistor is used to eliminate network signal reflection and enhance anti-interference capability.

[0007] The present invention provides a method for preventing over-tripping of low-voltage protection for mines, comprising the following steps:

[0008] Step 1: The switch device is connected to the CAN bus communication network;

[0009] Step 2: The switch equipment performs auto-negotiation networking;

[0010] Step 3: The main switch device periodically calls the branch switch device information;

[0011] Step 4: The switchgear detects sudden fault changes in real time;

[0012] Step 5. When the branch switch device detects a sudden fault change, it immediately sends a locking signal. After the main switch device detects a protection fault, it receives the locking signal from the branch switch device and locks the protection output. The branch switch device successfully trips to remove the fault or the switch refusal to trip times out, and sends an unlocking signal. The main switch device operates the output to remove the fault.

[0013] As an improvement to this solution, in step 2, the switching device performs auto-negotiation networking, including the following steps:

[0014] Step 2-1: Assign a device number and a registration code to the switch device. The main switch device number is initialized to 00, and the branch switch device number is initialized to FF. The registration code is generated by a random number.

[0015] Step 2-2: The main switch device initializes the branch switch device list to be empty and does not actively send a call message. If the branch switch device does not receive a call message for 5 seconds, it sends a heartbeat message every 1 second. The heartbeat message contains its device number and registration code.

[0016] Step 2-3: The main switch receives the heartbeat message from the branch switch, determines and registers its device number, and replies with the device number and registration code of the branch switch;

[0017] Step 2-4: The branch switch device receives the reply information from the main switch device and determines its assigned device number based on the registration code. The branch switch device no longer actively sends heartbeat messages.

[0018] Step 2-5: Repeat steps 2-3 and 2-4. All branch switch devices are registered with the main switch device, and the main switch device manages the branch switch device list.

[0019] As an improvement to this solution, in step 3, the method for the main switch device to periodically call the branch switch device information is: according to the registered branch switch device list, the main switch device calls a branch switch device information every 100 milliseconds, and the main switch device stops the periodic calling when it detects a sudden fault or receives a locking signal.

[0020] As an improvement to this solution, the calling message identifier is 7FF and the blocking message identifier is 000. When a message conflict occurs, the blocking message takes priority in occupying the communication network, thereby improving communication reliability and real-time performance.

[0021] As an improvement to this solution, the detection of sudden faults in the fast-trip protection adopts a floating threshold with a base value:

[0022] 4-11, Mutations were detected when is the rated current, To remove the real-time calculation current of the mutation point, Startup is caused by a sudden change in current.

[0023] , To calculate the sampling data sequence number, is the current sampling point number, is the number of sampling points per cycle;

[0024] 4-12, Update Compute data buffer, updated when no mutation is detected , updated to ;

[0025] 4-13. If a sudden change in the sampling data is detected at three consecutive points, it is determined to be a sudden change in the quick-break protection fault.

[0026] As an improvement to this solution, the leakage protection fault mutation detection method is as follows:

[0027] 4-21, Sampling mutations are detected when is the rated zero-sequence current, It is started by the sudden change of zero-sequence current.

[0028] , the sampling data mutation is detected at three consecutive points, it is determined to be a zero-sequence current fault mutation, and the sampling point number is recorded ;

[0029] 4-22, Mutations were detected when is the rated zero-sequence voltage, It is started by the zero sequence voltage mutation.

[0030] , the sampling data mutation is detected at three consecutive points, it is determined to be a zero-sequence voltage fault mutation, and the sampling point number is recorded ;

[0031] 4-23, starting sequence number from data window First, take the zero-sequence current and zero-sequence voltage half-cycle data, and calculate the correlation between the zero-sequence voltage derivative and the zero-sequence current based on the least squares method. ;

[0032] 4-24, It is determined to be a sudden change in leakage protection fault.

[0033] An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, any one of the methods for preventing over-tripping of low-voltage protection for mines is implemented.

[0034] A computer-readable storage medium stores computer instructions, which, when executed by a processor, implement a method for preventing over-tripping of low-voltage protection for mines.

[0035] Among them, the transient algorithm is only used for blocking signal detection and is not used as a protection exit algorithm, which improves the reliability of leakage protection.

[0036] The main switchgear and branch switchgear adopt different leakage protection action principles: the main switchgear adopts leakage protection based on the additional DC source principle, and the branch switchgear adopts selective leakage protection based on zero-sequence admittance.

[0037] Compared with the existing technology, the advantages of the present invention are as follows: the present invention uses a low-cost CAN bus as a communication network, self-negotiation networking, simple and reliable, easy to maintain; the calling and locking messages have different priorities, and when a message conflict occurs, the locking message takes priority to occupy the communication network, thereby improving communication reliability and real-time performance; no configuration is required, and it automatically adapts to changes in the power supply network topology; the main switch device regularly calls the branch switch device information, and stops calling when a fault mutation is detected or a locking signal is received, thereby reducing network traffic when a fault occurs and reducing bus communication conflicts; fault mutations are detected in real time through changes in fault components, and a floating threshold with a base value improves the reliability and sensitivity of fault detection; a transient algorithm is used Detect sudden fault changes and realize real-time locking of leakage protection. The transient algorithm is only used for locking signal detection and is not used as a protection exit algorithm, which improves the reliability of leakage protection. The same network realizes quick-break protection and leakage protection anti-overtripping system, which has universal applicability for low-voltage protection in coal mines. The main switchgear and branch switchgear adopt different leakage protection action principles to ensure the ease of use and reliability of ground fault anti-overtripping. The zero-sequence transient direction eliminates the disturbance influence caused by noise and improves the speed and anti-interference ability of the ground fault algorithm. It can realize full-line delay-free fast action of different protection types, without the need for delay coordination of traditional protection upper and lower levels, which has positive significance for building a safe and stable power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 It is a schematic diagram of the process structure of the present invention;

[0040] Figure 2 This is a reference diagram of the anti-over-tripping system of Example 1 of the present invention. DETAILED DESCRIPTION

[0041] The following descriptions of the embodiments refer to the accompanying drawings to illustrate specific embodiments in which the present invention may be implemented.

[0042] Example 1: Please refer to Figure 1 and Figure 2 As shown, embodiment 1 of the present invention provides a system for low-voltage protection and anti-overtripping for mines, including a main switch device KG1, four branch switch devices KG2~KG5, a CAN bus communication network, and terminal resistors. The main switch device KG1 realizes trunk power supply line fault detection and removal and network topology management, the branch switch devices KG2~KG5 realize branch power supply line fault detection and removal, the CAN bus communication network is used for information transmission of the switch devices, and the terminal resistors are used to eliminate network signal reflections and enhance anti-interference capabilities.

[0043] The master switch device KG1 and the four branch switch devices KG2 through KG5 are connected to the CAN bus communication network and, after normal operation, undergo auto-negotiation to establish a network. KG1's device number is initialized to 00, and KG2 through KG5's device numbers are initialized to FF. The registration code is generated by a random number generated by the device. Assume that the generated registration code for KG1 is 11, for KG2 it is 22, for KG3 it is 33, for KG4 it is 44, and for KG5 it is 55. KG1 initializes the branch switch device list to be empty and does not actively send summoning information. When KG2~KG5 do not receive the summoning information within 5 seconds, they send a heartbeat message every 1 second. The heartbeat message contains its device number FF and a random number registration code. KG1 receives the heartbeat messages from KG2~KG5, determines and registers its KG2~KG5 device numbers as 1~4 respectively, and replies to KG2~KG5 with device numbers 1~4 and registration codes 22~55 respectively. KG2~KG5 receives KG1's reply information, determines its assigned device number based on the registration code, and no longer actively sends heartbeat messages. KG2~KG5 are successfully registered by KG1. KG1 manages the KG2~KG5 list and summons a branch switch device information every 100 milliseconds.

[0044] When a fault occurs in the KG3 branch line, both the branch switch device KG3 and the main switch device KG1 detect a sudden fault change. KG1 detects the sudden fault change and stops the timed call. KG3 detects the sudden fault change and immediately sends a locking signal. KG1 receives the locking signal from KG3 and locks the protection outlet. KG3 trips successfully to cut off the fault or the switch refusal to trip times out and sends an unlocking signal. KG1 then operates the outlet to cut off the fault.

[0045] Example 2: Please refer to Figure 1 and Figure 2 As shown, a method for performing over-tripping protection using a mine low-voltage protection over-tripping protection system comprises the following steps:

[0046] Step 1: The switch device is connected to the CAN bus communication network;

[0047] Step 2: The switch equipment performs auto-negotiation networking;

[0048] Step 3: The main switch device periodically calls the branch switch device information;

[0049] Step 4: The switchgear detects sudden fault changes in real time;

[0050] Step 5. When the branch switch device detects a sudden fault change, it immediately sends a locking signal. After the main switch device detects a protection fault, it receives the locking signal from the branch switch device and locks the protection output. The branch switch device successfully trips to remove the fault or the switch refusal to trip times out, and sends an unlocking signal. The main switch device operates the output to remove the fault.

[0051] In step 2, the switching device performs auto-negotiation networking, including the following steps:

[0052] Step 2-1: Assign a device number and a registration code to the switch device. The main switch device number is initialized to 00, and the branch switch device number is initialized to FF. The registration code is generated by a random number.

[0053] Step 2-2: The main switch device initializes the branch switch device list to be empty and does not actively send a call message. If the branch switch device does not receive a call message for 5 seconds, it sends a heartbeat message every 1 second. The heartbeat message contains its device number and registration code.

[0054] Step 2-3: The main switch receives the heartbeat message from the branch switch, determines and registers its device number, and replies with the device number and registration code of the branch switch;

[0055] Step 2-4: The branch switch device receives the reply information from the main switch device and determines its assigned device number based on the registration code. The branch switch device no longer actively sends heartbeat messages.

[0056] Step 2-5: Repeat steps 2-3 and 2-4. All branch switch devices are registered with the main switch device, and the main switch device manages the branch switch device list.

[0057] In step 3, the method for the main switch device to periodically call the branch switch device information is: according to the registered branch switch device list, the main switch device calls a branch switch device information every 100 milliseconds, and the main switch device stops the periodic calling when it detects a sudden fault or receives a locking signal.

[0058] The calling message identifier is 7FF, and the blocking message identifier is 000. When a message conflict occurs, the blocking message takes priority in occupying the communication network, thereby improving communication reliability and real-time performance.

[0059] The detection of sudden faults of fast-break protection adopts a floating threshold with a base value. The specific steps are as follows:

[0060] 4-11, Mutations were detected when is the rated current, To remove the real-time calculation current of the mutation point, Startup is caused by a sudden change in current.

[0061] , To calculate the sampling data sequence number, is the current sampling point number, is the number of sampling points per cycle;

[0062] 4-12, Update Compute data buffer, updated when no mutation is detected , updated to ;

[0063] 4-13. If a sudden change in the sampling data is detected at three consecutive points, it is determined to be a sudden change in the quick-break protection fault.

[0064] Among them, the leakage protection fault mutation detection, the specific steps are as follows:

[0065] 4-21, Sampling mutations are detected when is the rated zero sequence current, It is started by the sudden change of zero-sequence current.

[0066] , the sampling data mutation is detected at three consecutive points, it is determined to be a zero-sequence current fault mutation, and the sampling point number is recorded ;

[0067] 4-22, Mutations were detected when is the rated zero-sequence voltage, It is started by the zero sequence voltage mutation.

[0068] , the sampling data mutation is detected at three consecutive points, it is determined to be a zero-sequence voltage fault mutation, and the sampling point number is recorded ;

[0069] 4-23, starting sequence number from data window First, take the zero-sequence current and zero-sequence voltage half-cycle data, and calculate the correlation between the zero-sequence voltage derivative and the zero-sequence current based on the least squares method. ;

[0070] 4-24, It is determined to be a sudden change in leakage protection fault.

[0071] The transient algorithm is only used for blocking signal detection and is not used as a protection exit algorithm, which improves the reliability of leakage protection.

[0072] The main switchgear and branch switchgear adopt different leakage protection action principles: the main switchgear adopts leakage protection based on the additional DC source principle, and the branch switchgear adopts selective leakage protection based on zero-sequence admittance.

[0073] The technical means disclosed in the solution of the present invention are not limited to the technical means disclosed in the above-mentioned embodiment, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A mine low voltage protection and anti-over-tripping system, characterized by: The system includes a main switch device, multiple branch switch devices, a CAN bus communication network, and terminal resistors. The main switch device realizes trunk power supply line fault detection and removal and network topology management. The branch switch devices realize branch power supply line fault detection and removal. The CAN bus communication network is used for information transmission between the switch devices. The terminal resistors are used to eliminate network signal reflections and enhance anti-interference capabilities. The details are as follows: It includes a main switch device KG1, four branch switch devices KG2~KG5, CAN bus communication network, and terminal resistors. The main switch device KG1 realizes the fault detection and removal of the trunk power supply line and network topology management. The branch switch devices KG2~KG5 realize the fault detection and removal of the branch power supply line. The CAN bus communication network is used for information transmission of the switch devices. The main switch device KG1 and the four branch switch devices KG2~KG5 are connected to the CAN bus communication network. After normal operation, they are automatically negotiated and networked. The device number of KG1 is initialized to 00, and the device numbers of KG2~KG5 are initialized to FF. The registration code is generated by the random number of the device. Assume that the generated registration code KG1 is 11, KG2 is 22, KG3 is 33, KG4 is 44, and KG5 is 55. The branch switch device list of KG1 is initialized to be empty and does not actively send a call message. If KG2~KG5 does not receive a call message for 5 seconds, it sends a heartbeat every 1 second. Heartbeat message contains its device number FF and random number registration code. KG1 receives the heartbeat message from KG2~KG5, determines and registers its KG2~KG5 device numbers as 1~4 respectively, and replies with the device numbers 1~4 and registration codes 22~55 of KG2~KG5 respectively. KG2~KG5 receives the reply information from KG1, determines its assigned device number according to the registration code, and no longer actively sends heartbeat message. KG2~KG5 is successfully registered by KG1. KG1 manages the KG2~KG5 list and calls a branch switch device information every 100 milliseconds. When a fault occurs in the KG3 branch line, both the branch switch device KG3 and the main switch device KG1 detect a sudden fault change. KG1 detects the sudden fault change and stops the timed call. KG3 detects the sudden fault change and immediately sends a locking signal. KG1 receives the locking signal from KG3 and locks the protection outlet. KG3 trips successfully to cut off the fault or the switch refusal to trip times out and sends an unlocking signal. KG1 then operates the outlet to cut off the fault.

2. A method for preventing over-tripping of low-voltage protection for mines, characterized in that: Utilizing the system for preventing over-tripping of low-voltage protection for mines according to claim 1, the method comprises the following steps: Step 1: The switch device is connected to the CAN bus communication network; Step 2: The switch device performs auto-negotiation networking; Step 3: The main switch device periodically calls the branch switch device information; Step 4: The switchgear detects sudden fault changes in real time; Step 5: When the branch switch detects a sudden fault change, it immediately sends a blocking signal. After the main switch detects a protection fault, it receives the blocking signal from the branch switch and blocks the protection output. If the branch switch successfully trips to clear the fault or the switch refuses to trip for a timeout, it sends an unlocking signal, and the main switch operates the output to clear the fault. In step 2, the switching device performs auto-negotiation networking, including the following steps: Step 2-1: Assign a device number and a registration code to the switch device. The main switch device number is initialized to 00, and the branch switch device number is initialized to FF. The registration code is generated by a random number. Step 2-2: The main switch device initializes the branch switch device list and is empty. It does not actively send a call message. If the branch switch device does not receive a call message within 5 seconds, it sends a heartbeat message every second. The heartbeat message contains its device number and registration code. Step 2-3: The main switch receives the heartbeat message from the branch switch, determines and registers its device number, and replies with the device number and registration code of the branch switch. In step 2-4, the branch switch device receives the reply information from the main switch device and determines the device number assigned to it according to the registration code. The branch switch device no longer actively sends heartbeat messages. Step 2-5 repeats steps (2-3) to (2-4), all branch switch devices are registered with the main switch device, and the main switch device manages the branch switch device list; In step 3, the method for the main switch device to periodically call the branch switch device information is as follows: according to the registered branch switch device list, the main switch device calls one branch switch device information every 100 milliseconds, and the main switch device stops the periodic calling when it detects a sudden fault or receives a blocking signal; The call message identifier is 7FF, and the blocking message identifier is 000. When a message conflict occurs, the blocking message takes priority in occupying the communication network, which improves communication reliability and real-time performance. The detection of sudden fault changes in quick-break protection uses a floating threshold with a base value: (4-11) Mutations were detected when is the rated current, To remove the real-time calculation current of the mutation point, Start for current mutation , n is the number of calculated sampling data, k is the number of current sampling point, and m is the number of sampling points per cycle; (4-12) Update Compute data buffer, updated when no mutation is detected , updated to ; (4-13) A sudden change in the sampling data is detected at three consecutive points, and it is determined to be a sudden change in the quick-break protection fault; The method for detecting sudden change of leakage protection fault is as follows: (4-21) Sampling mutations are detected when is the rated zero-sequence current, Startup for zero-sequence current sudden change , when a sudden change in the sampling data is detected at three consecutive points, it is determined to be a sudden change in the zero-sequence current fault, and the sampling point number Si is recorded; (4-22) Mutations were detected when is the rated zero-sequence voltage, Startup for zero sequence voltage sudden change , when a sudden change in the sampling data is detected at three consecutive points, it is determined to be a sudden change in the zero-sequence voltage fault, and the sampling point number Su is recorded; (4-23) Starting sequence number from the data window First, take the zero-sequence current and zero-sequence voltage half-cycle data, and calculate the correlation D between the zero-sequence voltage derivative and the zero-sequence current based on the least squares method; (4-24) It is determined to be a sudden change in leakage protection fault.

3. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method for preventing over-tripping of low-voltage protection for mines as described in claim 2 is implemented.

4. A computer-readable storage medium having computer instructions stored thereon, characterized in that: When the computer instructions are executed by the processor, the method for preventing over-tripping of low-voltage protection for mines as claimed in claim 2 is implemented.

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