Real-time monitoring device for latent fault of low-voltage loop

Abstract

The invention discloses a low-voltage loop latent fault real-time monitoring device, which comprises a controller, a current acquisition module, a voltage difference acquisition module, a phase voltage acquisition module, a management machine and a background master station, and is characterized in that the controller is respectively connected with the current acquisition module, the voltage difference acquisition module, the phase voltage acquisition module and the management machine, and the management machine is also connected with the background master station; the controller is further connected with a debugging network port, a B code time synchronization module, a watchdog, a wave recording storage module, a constant value storage module and an external real-time clock, the abnormal loss of the power supply loop is calculated by monitoring the electrical analog quantity of the power supply loop at the start end and the tail end of the power supply branch loop, the abnormal loss is analyzed, the ratio of inter-phase voltage and other data are analyzed, and the real-time performance of the power supply loop is improved. And the abnormal heating problem of the whole power supply branch loop is judged by measuring the electric energy loss, and an alarm is given in advance, so that the latent fault abnormal problem of the low-voltage loop is early warned before a fault occurs.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical monitoring, and in particular to a real-time monitoring device for latent faults in a low-voltage circuit. Background Art

[0002] Industrial enterprises have numerous low-voltage cabinets. In long-term operating enterprises such as petrochemicals, equipment ages over time and experiences increasing abnormalities. These abnormalities are often accompanied by rising temperatures. Conventional detection often uses temperature sensors for temperature measurement, but temperature sensors can only detect abnormal temperatures near the sensor installation location. Due to the large number of components in the low-voltage cabinet and the scattered fault points, it is impossible to install a large number of sensors, so the use of temperature sensors for monitoring is very limited. Since all abnormalities such as heating are caused by energy loss in the equipment, if the overall energy loss of regional equipment can be monitored, abnormal equipment experiencing heating can be indirectly identified.

[0003] The disadvantages of the existing technology are as follows:

[0004] 1: Poor accuracy. Traditional technology calculates virtual resistance by detecting the voltage difference between the busbar and the outgoing line.

[0005] 2. Poor real-time performance. Traditional technology uses a resistance loop tester to perform a timed power-off test.

[0006] 3: It consumes manpower costs and requires regular arrangement of professional personnel for on-site testing;

[0007] 4: Highly dangerous. During manual maintenance, electric shock accidents are likely to occur due to the live busbar.

[0008] 5: Easy to misjudge. Traditional technology monitors the degree of fever by installing a temperature measuring strap, which is easily affected by the internal working environment. Summary of the Invention

[0009] In order to make up for the deficiencies of the prior art, the embodiments of the present application propose a real-time monitoring device for latent faults in a low-voltage circuit to solve the problems existing in the prior art.

[0010] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0011] A real-time monitoring device for latent faults in a low-voltage circuit includes a controller, a current acquisition module, a pressure difference acquisition module, a phase voltage acquisition module, a management machine and a background master station. The controller is respectively connected to the current acquisition module, the pressure difference acquisition module, the phase voltage acquisition module and the management machine, and the management machine is also connected to the background master station. The controller is also connected to a debugging network port, a B code timing module, a watchdog, a recording storage module, a fixed value storage module and an external real-time clock.

[0012] As a further technical solution of the present invention: the current acquisition module includes a flexible Rogowski coil, a voltage follower, an isolation amplifier and an analog-to-digital conversion chip. The flexible Rogowski coil is connected to the voltage follower, the voltage follower is also connected to the isolation amplifier, and the isolation amplifier is also connected to the analog-to-digital conversion chip.

[0013] As a further technical solution of the present invention: the model of the voltage follower is LM358, the model of the isolation amplifier is CA-IS1300B25G, and the model of the analog-to-digital conversion chip is AD7616.

[0014] As a further technical solution of the present invention: the phase voltage acquisition module includes two voltage followers, two isolation amplifiers and an analog-to-digital conversion chip. The two voltage followers and the two isolation amplifiers constitute two data channels, a small channel and a large channel. The sampling range of the small channel is 1mV~250mV, and the sampling range of the large channel is 250mV~4V.

[0015] As a further technical solution of the present invention: the model of the voltage follower is LM358, the model of the isolation amplifier is CA-IS1300B25G, and the model of the analog-to-digital conversion chip is AD7616.

[0016] As a further technical solution of the present invention: the controller is a single chip microcomputer.

[0017] As a further technical solution of the present invention: the controller is connected to the management machine via an RS485 line.

[0018] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0019] The present invention calculates the abnormal loss of the power supply circuit by monitoring the electrical analog quantity of the power supply circuit at the beginning and end of the power supply branch circuit. By analyzing the abnormal loss, the ratio of phase voltage and other data, different levels of warning information are obtained. The measurement of power loss is used to judge the abnormal heating problem of the entire power supply branch circuit, and an alarm is issued in advance, thereby warning of potential abnormal fault problems in the low-voltage circuit before a fault occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is an overall block diagram of the present invention;

[0021] Figure 2 This is the block diagram of the current acquisition part;

[0022] Figure 3 This is the circuit diagram of the current collection part;

[0023] Figure 4 This is the block diagram of the voltage acquisition part;

[0024] Figure 5 This is the circuit diagram of the voltage acquisition part. DETAILED DESCRIPTION

[0025] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. 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.

[0026] like Figure 1-5 As shown, a real-time monitoring device for latent faults in a low-voltage circuit includes a controller, a current acquisition module, a pressure difference acquisition module, a phase voltage acquisition module, a management machine and a background master station. The controller is respectively connected to the current acquisition module, the pressure difference acquisition module, the phase voltage acquisition module and the management machine, and the management machine is also connected to the background master station. The controller is also connected to a debugging network port, a B code timing module, a watchdog, a recording storage module, a fixed value storage module and an external real-time clock.

[0027] The monitoring device collects the busbar-side voltage U1, line-side voltage U2, busbar / line-side pressure difference △U, and loop current I within the cabinet. Based on Ohm's law (U=I*R) and P=I2*R, it calculates the loop's virtual resistance and virtual loss using △U and I. The virtual losses of different phase loops are compared with historical average loop loss data. When the calculated virtual resistance and virtual loss of the monitored loop exceed a threshold, the monitoring device uploads an alarm to the master station backend via RS485, indirectly identifying abnormal devices experiencing heating.

[0028] The equivalent loop impedance is calculated by R = ▲U / I, and the equivalent loop loss is calculated by P = ▲U / I;

[0029] Compare the equivalent impedance and equivalent loss of the three-phase circuit:

[0030] 1: RA / RB, RB / RC, and RC / RA compare the loop resistances between the three-phase circuits, and issue a warning alarm if the resistance exceeds the threshold.

[0031] 2: Compare the loop losses between the three-phase PA / PB, PB / PC, and PC / PA circuits, and issue a warning alarm if the threshold is exceeded.

[0032] Compare the equivalent impedance and equivalent loss of the three-phase circuit with historical trends:

[0033] 1: The current average effective value of the impedance of RA, RB, and RC is compared with the previous historical data value, and an early warning alarm is issued when the threshold is exceeded;

[0034] 2: The current average effective value of PA, PB, and PC losses is compared with the previous historical data values, and an early warning alarm is issued if the threshold is exceeded.

[0035] Here’s how it works:

[0036] Current acquisition module:

[0037] The RD2050 Rogowski coil is a hollow, toroidal coil designed specifically for collecting high AC currents. It's designed to be placed directly on the drawer cable to measure AC current. It offers high linearity, simple installation, and no risk of open circuits. Its maximum input-output ratio is 1000A:100mV.

[0038] When the primary current of the drawer cabinet is I, the output voltage of the Rogowski coil is V1 = (I / 1000) * 100mV = I / 10mV. After V1 passes through the voltage follower to the isolation amplifier CA-IS1300B25G (gain is 8.2), the voltage is V2 = (I / 10mV) * 8.2, and then V2 is sent to the AD chip for analog-to-digital conversion.

[0039] Busbar / line side pressure difference △U collection:

[0040] When the primary current I (40A ~ 1000A) flows through the low-voltage drawer cabinet contact, the contact resistance R is generally between 100uΩ and 1500uΩ. According to Ohm's law, a small signal voltage, namely the voltage difference △U = I*R, is generated at both ends of the contact, which is generally between 4mV and 1.5V. Due to the wide range of △U, in order to improve the sampling accuracy, △U is sampled in two sections. The sampling range of the small channel is 1mV to 250mV, and the sampling range of the large channel is 250mV to 4V.

[0041] The △U of the large and small channels pass through the voltage followers to the isolation amplifier CA-I S1300B25G respectively. After isolation and amplification, △U is sent to the AD chip for analog-to-digital conversion.

[0042] By adopting the above solution, the following technical effects can be achieved:

[0043] 1. Wide sampling range: 1mV~4VAC; 2. High sampling accuracy: error within 0.2mV at normal temperature; 3. Strong real-time performance: the monitoring device performs real-time sampling and calculations, and sends alarms to the backend; 4. Accurate fault location: through backend data analysis, it can accurately locate the fault of a branch circuit.

[0044] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0045] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment have also been appropriately combined to form other implementation methods that are easy for those skilled in the art to understand.

Claims

1. A real-time monitoring device for latent faults in a low-voltage circuit, comprising a controller, a current acquisition module, a pressure difference acquisition module, a phase voltage acquisition module, a management machine, and a background master station, characterized in that: The controller is respectively connected to the current acquisition module, the pressure difference acquisition module, the phase voltage acquisition module and the management machine, the management machine is also connected to the background main station, and the controller is also connected to the debugging network port, the B code timing module, the watchdog, the recording storage module, the fixed value storage module and the external real-time clock.

2. A low-voltage circuit latent fault real-time monitoring device according to claim 1, characterized in that: The current acquisition module includes a flexible Rogowski coil, a voltage follower, an isolation amplifier and an analog-to-digital conversion chip. The flexible Rogowski coil is connected to the voltage follower, the voltage follower is further connected to the isolation amplifier, and the isolation amplifier is further connected to the analog-to-digital conversion chip.

3. A low-voltage circuit latent fault real-time monitoring device according to claim 2, characterized in that: The model of the voltage follower is LM358, the model of the isolation amplifier is CA-IS1300B25G, and the model of the analog-to-digital conversion chip is AD7616.

4. A low-voltage circuit latent fault real-time monitoring device according to claim 1, characterized in that: The phase voltage acquisition module includes two voltage followers, two isolation amplifiers and an analog-to-digital conversion chip. The two voltage followers and two isolation amplifiers form two data channels, a small channel and a large channel. The sampling range of the small channel is 1mV to 250mV, and the sampling range of the large channel is 250mV to 4V.

5. A low-voltage circuit latent fault real-time monitoring device according to claim 4, characterized in that: The model of the voltage follower is LM358, the model of the isolation amplifier is CA-IS1300B25G, and the model of the analog-to-digital conversion chip is AD7616.

6. A low-voltage circuit latent fault real-time monitoring device according to claim 1, characterized in that: The controller is a single chip microcomputer.

7. The device for real-time monitoring of latent faults in a low-voltage circuit according to claim 1, characterized in that: The controller is connected to the management machine via an RS485 line.

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