Offline leakage line selection system and method for step-by-step detection of coal mine multi-loop starter

Abstract

The invention relates to an off-line leakage line selection system and method for step-by-step detection of a coal mine multi-loop starter, and the method comprises the steps: detecting the zero-sequence voltage and three-phase voltage of a main line through an insulation detection module, calculating the phase difference between the zero-sequence voltage and the three-phase voltage, and judging a line fault if the phase difference exceeds a fixed value; the control module controls the loops to start and stop in sequence, detects the insulation resistance value of the main line through the high-voltage power supply module and the insulation detection module, and determines a fault branch according to the insulation resistance value. According to the method, whether the leakage fault exists or not is judged through the zero-sequence voltage phase difference, then the fault branch is judged through additional direct current automatic detection, the judgment time is short, and the line selection accuracy is high; under the condition that a main loop is not electrified, an additional high-voltage direct-current power supply is adopted, the insulation resistance to ground of each branch is detected, and the detectable range is up to 3 megohms and is only hundreds of kilohms larger than the detectable range of the insulation resistance of the additional direct-current power supply.

Description

Technical Field

[0001] The present invention relates to the technical field of protection circuits for multi-circuit starters in coal mines, and in particular to an offline leakage line selection system and method for step-by-step detection of multi-circuit starters in coal mines. Background Art

[0002] The leakage line selection method currently used in multi-circuit vacuum electromagnetic starters for fully mechanized mining working faces in underground coal mines is basically to detect the zero-sequence current on the load side of each main circuit. If the zero-sequence current is greater than the set value, the leakage protection will be activated.

[0003] The traditional multi-circuit starter leakage line selection method is limited by factors such as the small value of the short zero-sequence current in the load line of the fully mechanized mining working face and the susceptibility of the zero-sequence current to variable frequency harmonic interference. The leakage line selection accuracy is poor and false operation problems often occur. The fault line needs to be manually confirmed circuit by circuit, which is time-consuming and labor-intensive. Summary of the Invention

[0004] In response to the above problems, the present invention proposes an offline leakage line selection system and method for step-by-step detection of coal mine multi-circuit starters. The fault branch is determined by a comprehensive judgment method that combines online detection of the phase difference between the total line zero-sequence voltage and the phase voltage with offline detection of the branch insulation resistance to ground, thereby greatly improving the accuracy of leakage line selection of multi-circuit electromagnetic starters for mines.

[0005] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] The present invention provides an offline leakage line selection system for step-by-step detection of a multi-circuit starter in a coal mine. The system comprises a control module, an insulation detection module and a high-voltage power supply module. The control module is connected to the insulation detection module and the high-voltage power supply module. The insulation detection module and the high-voltage power supply module are respectively connected to the load side of the main line disconnector of the multi-circuit starter in the coal mine. The insulation detection module detects the zero-sequence voltage and three-phase voltage of the main line, calculates the phase difference between the zero-sequence voltage and the three-phase voltage, and determines a line fault when the phase difference exceeds a fixed value. The control module controls the sequential start and stop of each circuit and detects the insulation resistance of the main line through the high-voltage power supply module and the insulation detection module, and determines the faulty branch based on the insulation resistance.

[0007] The present invention also provides an offline leakage line selection method for step-by-step detection of multi-circuit starters in coal mines. The offline leakage line selection system based on the above-mentioned step-by-step detection of multi-circuit starters in coal mines includes the following steps:

[0008] S1, connect the insulation detection module and high-voltage power supply module to the main circuit of the coal mine multi-circuit starter;

[0009] S2, the insulation detection module detects the total line zero-sequence voltage and three-phase voltage through a voltage transformer, analyzes the collected three-phase voltage signal and zero-sequence voltage signal, calculates the phase difference between the zero-sequence voltage and each phase voltage, and determines whether a leakage fault occurs in the total line and associated branches;

[0010] S3: If a leakage fault occurs, the control module controls the main circuit disconnector and all associated branch contactors on the load side of the disconnector to open;

[0011] In step S4, the control module connects the high-voltage power supply module through the insulation detection module. The high-voltage power supply module outputs a DC voltage to the main circuit on the load side of the disconnector. The control module closes the contactors of each associated branch one by one. The insulation detection module detects the insulation resistance of the main circuit to the ground in real time. If the insulation resistance is lower than the set value, the control module determines that the currently closed branch is a faulty branch.

[0012] Furthermore, in step S1, the primary winding of the voltage transformer of the insulation detection module is connected to the load side of the main line disconnector, the three-phase voltage of the secondary winding is connected to the control module, and the primary zero-sequence winding is connected to the insulation detection module after being stepped down by the zero-sequence voltage transformer.

[0013] Furthermore, in step S2, the insulation detection module calculates the phase difference φ between the zero-sequence voltage and each phase voltage. 0A 、φ 0B 、φ 0C , if or If the value is greater than the set value, the insulation detection module determines that a leakage fault has occurred in the associated branch of the main circuit.

[0014] Furthermore, in step S4, the high-voltage power supply module outputs a 3 kV DC voltage.

[0015] In the present invention, when the phase difference between the zero-sequence voltage and the phase voltage of the total line on the input side of the multi-circuit vacuum electromagnetic starter is greater than the set action value, the control module disconnects the total line disconnector and all branch contactors. When the load side of the disconnector is not energized (offline), a full-time personnel confirms that the load side line and personnel are safe. By applying a 3kV DC voltage between the load side of the disconnector and the ground, each branch contactor is sequentially attracted. Through the principle of additional DC voltage, the insulation resistance of each branch line and motor to the ground can be detected. If it is lower than the set value, it is determined to be a faulty branch. This method triggers the leakage line selection diagnosis mechanism when the phase difference between the zero-sequence voltage and the phase voltage is greater than the action value, detects the branch insulation resistance through the additional DC principle, and automatically locates the faulty branch. The line selection accuracy is high and no human intervention is required.

[0016] The beneficial effects of the present invention are:

[0017] (1) The present invention first determines whether there is a leakage fault by the zero-sequence voltage phase difference, and then automatically detects and determines the fault branch through additional DC, which shortens the judgment time and increases the line selection accuracy.

[0018] (2) The present invention uses an additional high-voltage DC power supply to detect the insulation resistance of each branch to the ground when the main circuit is not energized. The detection range is up to 3MΩ, which is greater than the traditional method of adding a low DC voltage insulation resistance with a detection range of only a few hundred kΩ. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a structural block diagram of the offline leakage line selection system for step-by-step detection of coal mine multi-circuit starters according to the present invention;

[0020] Figure 2 This is a schematic diagram of the offline leakage line selection system for step-by-step detection of coal mine multi-circuit starters according to the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention and the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] like Figure 1 The illustrated system is an offline leakage line selection system for step-by-step detection of a multi-circuit starter in a coal mine, comprising a control module 7, an insulation detection module 2, and a high-voltage power supply module 4. The control module 7 is connected to the insulation detection module 2 and the high-voltage power supply module 4. The insulation detection module 2 and the high-voltage power supply module 4 are respectively connected to the load side of the disconnector 5 of the main line 1 of the multi-circuit starter in the coal mine. The zero-sequence voltage and three-phase voltage of the main line 1 are detected by the insulation detection module 2. A 3kV DC power supply is added to the main line 1 by the high-voltage power supply module 4. The insulation resistance of the main line 1 is detected by the insulation detection module 2. The insulation detection module 2 determines whether an associated branch 3 of the main line has a leakage fault by calculating the phase difference between the zero-sequence voltage and the three-phase voltage. The contactor 6 of the associated branch 3 is controlled to open and close by the control module 7, and the faulty branch is determined based on the insulation resistance transmitted by the insulation detection module 2.

[0023] Specifically, combined Figure 2 As shown, the offline leakage line selection method for step-by-step detection of a coal mine multi-circuit starter of the present invention comprises the following steps:

[0024] S1, connect the insulation detection module ZB and the high-voltage power supply module U1 to the main circuit of the coal mine multi-circuit starter. Among them, the primary windings A, B, and C of the voltage transformer TV of the insulation detection module ZB are connected to the load side of the disconnector of the main circuit, the three-phase voltage of the secondary windings a, b, and c is connected to the control module WG, and the primary zero-sequence winding N is connected to the insulation detection module ZB after being stepped down by the zero-sequence voltage transformer TL;

[0025] S2, the insulation detection module ZB detects the zero-sequence voltage and three-phase voltage of the main line through the voltage transformer TV;

[0026] S3, the insulation detection module ZB uses digital signal processing methods to analyze the collected three-phase voltage signals and zero-sequence voltage signals, and calculates the phase difference φ between the zero-sequence voltage and each phase voltage. 0A 、φ 0B 、φ 0C , if or If it is greater than the set value, it is judged that a leakage fault has occurred in the associated branch of the main circuit;

[0027] S4, then, the control module WG controls the main circuit disconnector and all associated branch contactors on the load side of the disconnector to open;

[0028] S5. After the control module WG receives the manually triggered offline line selection instruction, it controls the insulation detection module ZB detection output port to connect and make the high-voltage relay K energize, and connect the high-voltage power supply module U1. The high-voltage power supply module U1 outputs a 3kV DC voltage, which is connected to the load side of the main line disconnector through the resistor R1, the relay contact K, and the choke coil L1, and then connected to the insulation detection module ZB detection input port through the insulation resistance RL of the main line to ground. During the closing period of the high-voltage relay K, the control module WG controls the contactors of each branch to close one by one, and detects the insulation resistance of the main line to ground in real time through the insulation detection module ZB. If the insulation resistance is higher than the set value, the control module WG determines that the insulation of the current closed branch is normal, opens the branch contactor, and continues to control the closing of the next branch contactor. If the insulation value is lower than the set value, the control module WG determines that the current closed branch is a fault branch, outputs a fault alarm message, and the leakage line selection determination process is completed.

[0029] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. An offline leakage line selection system for step-by-step detection of multi-circuit starters in coal mines, characterized by: It includes a control module, an insulation detection module and a high-voltage power supply module. The control module is connected to the insulation detection module and the high-voltage power supply module. The insulation detection module and the high-voltage power supply module are respectively connected to the load side of the main line disconnector of the coal mine multi-circuit starter. The insulation detection module detects the zero-sequence voltage and three-phase voltage of the main line, calculates the phase difference between the zero-sequence voltage and the three-phase voltage, and determines the line fault if it exceeds a set value. The control module controls the start and stop of each circuit in sequence and detects the insulation resistance of the main line through the high-voltage power supply module and the insulation detection module, and determines the fault branch based on the insulation resistance.

2. An offline leakage line selection method for step-by-step detection of multi-circuit starters in coal mines, based on the offline leakage line selection system for step-by-step detection of multi-circuit starters in coal mines according to claim 1, characterized in that: The steps include: S1, connect the insulation detection module and high-voltage power supply module to the main circuit of the coal mine multi-circuit starter; S2, the insulation detection module detects the total line zero-sequence voltage and three-phase voltage through a voltage transformer, analyzes the collected three-phase voltage signal and zero-sequence voltage signal, calculates the phase difference between the zero-sequence voltage and each phase voltage, and determines whether a leakage fault occurs in the total line and associated branches; S3, the control module controls the main circuit disconnector and all associated branch contactors on the load side of the disconnector to open; In step S4, the control module connects the high-voltage power supply module through the insulation detection module. The high-voltage power supply module outputs a DC voltage to the main circuit on the load side of the disconnector. The control module closes the contactors of each associated branch one by one. The insulation detection module detects the insulation resistance of the main circuit to the ground in real time. If the insulation resistance is lower than the set value, the control module determines that the currently closed branch is a faulty branch.

3. The offline leakage line selection method for step-by-step detection of multi-circuit starters in coal mines according to claim 2 is characterized in that: In step S1, the primary winding of the voltage transformer of the insulation detection module is connected to the load side of the main line disconnector, the three-phase voltage of the secondary winding is connected to the insulation detection module, and the primary zero-sequence winding is connected to the insulation detection module after being stepped down by the zero-sequence voltage transformer.

4. The offline leakage line selection method for step-by-step detection of multi-circuit starters in coal mines according to claim 2 is characterized in that: In step S2, the insulation detection module calculates the phase difference φ between the zero-sequence voltage and each phase voltage 0A 、φ 0B 、φ 0C , if or If the value is greater than the set value, the insulation detection module determines that a leakage fault has occurred in the associated branch of the main circuit.

5. The offline leakage line selection method for step-by-step detection of multi-circuit starters in coal mines according to claim 2 is characterized in that: In step S4, the high-voltage power supply module outputs a 3 kV DC voltage.

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