On-line monitoring device for three-phase synchronism of switch

Abstract

The utility model relates to a switch three-phase synchronism on-line monitoring device comprising an on-line monitoring device body which is composed of a current sampling unit, an input correction unit, a current waveform analysis unit, a timing comparison unit, a register and a display unit which are connected in sequence. Wherein the current waveform analysis unit is also in sampling connection with a switch auxiliary contact, the current sampling unit is used for carrying out real-time sampling and analog-to-digital conversion on a current measurement loop when the switch is switched on, and the input correction unit is used for carrying out deviation and proportion correction. The current waveform analysis unit is used for analyzing a current waveform data sequence, the timing comparison unit is used for timing three-phase current abrupt change and comparing a measured time value, and the register and the display unit are used for outputting a detection result. The device has the advantages of being simple and reasonable in structure, practical and safe, and capable of monitoring the three-phase asynchronism when the switch is switched on and switched off in real time and discovering switch characteristic degradation in time.

Description

Technical Field

[0001] The utility model belongs to the technical field of switch three-phase synchronization monitoring devices, and particularly relates to an on-line monitoring device for switch three-phase synchronization. Background Technique

[0002] With the increase of the service time of high-voltage switches in the coal mine power supply system, the deterioration of mechanical characteristics will cause the increase of three-phase non-synchronization. The closing and opening synchronization is an important parameter of the mechanical characteristics of the circuit breaker, that is, the time difference when the contacts contact or separate simultaneously during closing and opening. The increase of this parameter will cause the following problems:

[0003] (1). In a neutral point non-grounding system, voltage displacement occurs, generating zero-sequence current, and it is necessary to increase the setting value of the zero-sequence protection, reducing the sensitivity of the protection;

[0004] (2). The circuit breaker is prone to overvoltage, especially in the case of closing one phase first, which is more serious than closing two phases first. It will seriously threaten the insulation of the transformer neutral point in the neutral point non-grounding system and may cause the explosion of the neutral point lightning arrester;

[0005] (3). When the circuit breaker closes on a three-phase short circuit, if two phases close first, the voltage of the unclosed phase will increase, increasing the pre-breakdown length, and at the same time, higher requirements are also put forward for the mechanical strength of the arc extinguishing chamber;

[0006] (4). It will cause a large difference in three-phase currents and may cause overcurrent tripping of the protection.

[0007] At present, the detection of switch three-phase synchronization is carried out by using a special instrument during the power outage maintenance time. This method requires powering off the equipment, which affects the production efficiency.

[0008] Therefore, an on-line monitoring device for switch three-phase synchronization is designed to overcome the above problems. Content of the Utility Model

[0009] The purpose of the utility model is to overcome the deficiencies existing in the prior art, and to provide an on-line monitoring device for switch three-phase synchronization with a simple and reasonable structure, practical and safe, which can monitor the three-phase non-synchronization in real time during the closing and opening of the switch, timely detect the deterioration of the switch characteristics, is convenient for installation and use, saves time and manpower, and does not require special power outage detection.

[0010] The utility model is realized through the following technical solutions: A three-phase synchronization on-line monitoring device for switches, including the on-line monitoring device body, which is composed of a current sampling unit, an input correction unit, a current waveform analysis unit, a timing comparison unit, a register and a display unit connected in sequence. The current waveform analysis unit is also connected to the sampling of the switch auxiliary contact. The current sampling unit is used to perform real-time sampling and analog-to-digital conversion on the current measurement circuit when the switch is closed. The input correction unit is used to perform deviation and ratio correction. The current waveform analysis unit is used for analyzing the current waveform data sequence. The timing comparison unit is used to time the sudden change of the three-phase current and compare the measured time values. The register and the display unit are used to output the detection results.

[0011] Preferably, the current sampling unit consists of three current sampling probes and three analog-to-digital converters respectively connected to the three current sampling probes. The three current sampling probes are used to respectively perform real-time sampling on the phase A current, phase B current and phase C current of the current measurement circuit when the switch is closed. The other end of the analog-to-digital converter far from the current sampling probe is connected to the input correction unit.

[0012] Preferably, the timing comparison unit consists of a phase A microsecond timer, a phase B microsecond timer, a phase C microsecond timer and a comparator. The phase A microsecond timer, the phase B microsecond timer and the phase C microsecond timer are connected in parallel. One end of the phase A microsecond timer, the phase B microsecond timer and the phase C microsecond timer is connected to the current waveform analysis unit, and the other end is connected to the register. The phase C microsecond timer is also connected to the comparator. The comparator is used to compare the time values measured by the phase A microsecond timer, the phase B microsecond timer and the phase C microsecond timer with the phase A time t1 respectively, which is the contact time of the three-phase contacts when the switch is closed, and obtain the three-phase non-synchronization result. The detection results are output through the register and the display in sequence, so that the maintenance personnel can know the three-phase synchronization result of the switch.

[0013] Compared with the prior art, the beneficial effects of the utility model are as follows:

[0014] The device designed by the utility model can solve the problem of on-line monitoring of the three-phase non-synchronization time of the switch, timely discover the deterioration of the switch characteristics, so that the maintenance personnel can handle it in time, and prevent the switch deterioration from developing into an accident. By performing real-time sampling on the current measurement circuit when the switch is closed and analyzing the measured current waveform data sequence, the three-phase non-synchronization time values of the switch opening and closing are obtained. Compared with detecting the three-phase non-synchronization of the switch opening and closing by performing switch characteristic tests during power outage, this device is convenient to install and use, saves time and manpower, and does not require special power outage detection. Description of the Drawings

[0015] Figure 1 This is a schematic structural diagram of the present utility model. Detailed implementation manners

[0016] To enable those of ordinary skill in the art to more clearly understand the purpose, technical solution and advantages of the present utility model, the following further elaborates on the present utility model in conjunction with the accompanying drawings and embodiments.

[0017] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", "lateral", "vertical", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present utility model and does not indicate or imply that the device or component referred to must have a specific orientation. Therefore, it should not be construed as a limitation to the present utility model.

[0018] The following will introduce the present utility model in detail with reference to the accompanying drawings: As Figure 1 shown, a switch three-phase synchronization on-line monitoring device includes an on-line monitoring device body. The on-line monitoring device body is composed of a current sampling unit 1, an input correction unit 2, a current waveform analysis unit 3, a timing comparison unit 4, a register 5 and a display unit 6 connected in sequence. Among them, the current waveform analysis unit 3 is also connected to a switch auxiliary contact sampling 7. The current sampling unit 1 is used to perform real-time sampling and analog-to-digital conversion on the current measurement circuit when the switch is closed. The input correction unit 2 is used to perform deviation and ratio correction. The current waveform analysis unit 3 is used for analyzing the current waveform data sequence. The timing comparison unit 4 is used to time the sudden change of the three-phase current and compare the measured time value. The register 5 and the display unit 6 are used to output the detection result.

[0019] The current sampling unit 1 is composed of three current sampling probes 13 and three analog-to-digital converters 8 respectively connected to the three current sampling probes 13. The three current sampling probes 13 are used to respectively perform real-time sampling on the phase A current, phase B current and phase C current of the current measurement circuit when the switch is closed. The other end of the analog-to-digital converter 8 far from the current sampling probe 13 is connected to the input correction unit 2.

[0020] The timing comparison unit 4 is composed of a phase-A microsecond timer 9, a phase-B microsecond timer 10, a phase-C microsecond timer 11, and a comparator 12. Among them, the phase-A microsecond timer 9, the phase-B microsecond timer 10, and the phase-C microsecond timer 11 are connected in parallel. One end of the phase-A microsecond timer 9, the phase-B microsecond timer 10, and the phase-C microsecond timer 11 is connected to the current waveform analysis unit 3, and the other end is connected to the register 5. The phase-C microsecond timer 11 is also connected to the comparator 12. The comparator 12 respectively compares the time values measured by the phase-A microsecond timer 9, the phase-B microsecond timer 10, and the phase-C microsecond timer 11 with the phase-A time t1, which is the contact time of the three-phase contacts when the switch is closed, and obtains the three-phase non-simultaneity result. The detection results are output through the register and the display in sequence, so that the maintenance personnel can know the three-phase simultaneity result of the switch.

[0021] The working principle of the present utility model is as follows:

[0022] By performing real-time sampling on the current measurement circuit of the switch through a current sampling probe when the switch is closed, performing analog-to-digital conversion through the current sampling unit, performing deviation and ratio correction through the input correction unit, and analyzing the measured current waveform data sequence through the current waveform analysis unit. Because there is a cable or bus connected to the switch line side, which is equivalent to a capacitive load. When the switch is closed, there will be a small current mutation when the current charges the capacitive load, and this current mutation is linearly related to the contact time of the switch contacts. The closing time of the switch is detected through the switch auxiliary contact sampling. The high-speed microsecond timer inside the processor is used to time the three-phase current mutations. The comparator compares the measured time value with the phase-A time t1, which is the contact time of the three-phase contacts when the switch is closed, and obtains the three-phase non-simultaneity result. The detection results are output through the register and the display, so that the maintenance personnel can know the three-phase simultaneity result of the switch. Embodiment

[0023] The present utility model is verified for its effect on the P / VII-12 type switchgear cabinet. This device can display the closing time of the three-phase contacts of the switch when the switch is closed to charge the cable, and the three-phase non-simultaneity result can be obtained. Through this device, various problems caused by excessive three-phase non-simultaneity time of the switch can be predicted in advance, so as to improve the reliability of safe power supply.

[0024] The specific embodiments described herein are only illustrative of the principles and effects of the present utility model, and are not used to limit the present utility model. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present utility model. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present utility model should still be covered by the claims of the present utility model.

Claims

1. An on-line monitoring device for switch three-phase synchronization, comprising an on-line monitoring device body, characterized in that: The on-line monitoring device body is composed of a current sampling unit (1), an input correction unit (2), a current waveform analysis unit (3), a timing comparison unit (4), a register (5) and a display unit (6) which are connected in sequence. The current waveform analysis unit (3) is also connected to the switch auxiliary contact sampling (7). The current sampling unit (1) is used to perform real-time sampling and analog-to-digital conversion on the current measurement circuit when the switch is closed. The input correction unit (2) is used to perform deviation and ratio correction. The current waveform analysis unit (3) is used for analyzing the current waveform data sequence. The timing comparison unit (4) is used to time the sudden change of three-phase current and compare the measured time values. The register (5) and the display unit (6) are used to output the detection results.

2. The on-line monitoring device for the switch three-phase synchronization according to claim 1, characterized in that: The current sampling unit (1) is composed of three current sampling probes (13) and three analog-to-digital converters (8) respectively connected to the three current sampling probes (13). The three current sampling probes (13) are used to respectively perform real-time sampling on the phase A current, phase B current and phase C current of the current measurement circuit when the switch is closed. The other end of the analog-to-digital converter (8) far from the current sampling probe (13) is connected to the input correction unit (2).

3. The on-line monitoring device for the switching three-phase synchronization according to claim 1, characterized in that: The timing comparison unit (4) is composed of a phase A microsecond timer (9), a phase B microsecond timer (10), a phase C microsecond timer (11) and a comparator (12). The phase A microsecond timer (9), the phase B microsecond timer (10) and the phase C microsecond timer (11) are connected in parallel. One end of the phase A microsecond timer (9), the phase B microsecond timer (10) and the phase C microsecond timer (11) is connected to the current waveform analysis unit (3), and the other end is connected to the register (5). The phase C microsecond timer (11) is also connected to the comparator (12). The comparator (12) is used to compare the time values measured by the phase A microsecond timer (9), the phase B microsecond timer (10) and the phase C microsecond timer (11) with the phase A time t1 respectively, which is the contact time of the three-phase contacts when the switch is closed, and obtain the three-phase non-simultaneity result. The detection results are output through the register and the display in sequence, so that the maintenance personnel can know the three-phase simultaneity result of the switch.

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