CN102891532B - Portable microcomputer charging protection device and method - Google Patents

Abstract

The invention relates to a portable microcomputer charging protection device and method, which belong to the field of electrical engineering and automation. Output terminal and installation panel; the invention has the advantages of small size, light weight, portability, low power, long-distance communication, short time for device protection and removal of faults, large setting range of operating current and operating time, and easy setting and operation. The mode can not only be set by four sets of trip switches, but also by the advantages of comprehensive digital relay settings.

Description

A portable microcomputer charging protection device and method

technical field

The invention belongs to the field of electrical engineering and automation thereof, and in particular relates to a portable microcomputer charging protection device and method.

Background technique

When carrying out charging tests on newly put into operation transmission lines and new equipment, a device called charging protection is put into operation. When a short-circuit fault occurs in the new input equipment due to insulation breakdown or insufficient electrical safety distance of the transmission line, the charging protection device will act to quickly cut off the faulty line or equipment. After the charging test is completed, the charging protection device will stop operating. The device can avoid the failure of the faulty line or equipment to be cut off in time, resulting in the power failure of the associated transmission line in the power system, and the disconnection of the associated power plant and the power system, which cannot operate safely and stably. At present, the charging protection devices used in power system reconstruction and expansion, new power plants and substation projects are generally composed of 16 electromagnetic current relays, time relays, signal relays and intermediate relays. When a short-circuit occurs in a newly invested transmission line or equipment, the current of the power system rises beyond the set current value of the charging protection device, and the charging protection device operates to cut off the faulty line or equipment.

However, the current technology has the following defects:

(1) The charging protection device is a three-stage current protection device composed of 16 electromagnetic current relays, time relays, signal relays and intermediate relays. It is bulky and not easy to carry for testing;

(2) For the first charging test of transmission lines with a voltage level of 220kV and above, the protection action time is required to be no more than 10mms, and the inherent action time of the charging protection device composed of 16 electromagnetic relays is close to 100mms, which makes the protection and removal of faults take a long time, causing power failure. The system fluctuates, and its safe and stable operation is seriously affected;

(3) The first charging test of a 500kV transmission line requires a minimum setting current of 0.3A for charging protection, but the minimum setting current for the charging protection device is 0.5A using a DL-type electromagnetic current relay. , the charging protection may refuse to operate, and the fault cannot be removed;

(4) Setting of the charging protection operating current and operating time: the technician first opens the sealing cover of the electromagnetic current relay and the time relay, and then toggles the relay setting handle to set the fixed value, so the setting is inconvenient, the setting value is inaccurate, and the error big;

(5) When the short-circuit current of the power system is close to the charging protection action current, the contacts of the electromagnetic current relay vibrate and generate an arc, which is easy to burn out the current relay;

(6) The electromagnetic interference of power plants and substations is relatively large, which makes the charging protection device composed of electromagnetic relays prone to malfunction;

(7) The remote "four remote" communication between the charging protection device and the microcomputer monitoring system of the power plant and substation cannot be realized, and the remote control center cannot understand the charging protection action information;

(8) The electromagnetic relay adopts the electromagnetic working principle, so the power loss of the coil of the relay is large, and the coil is easy to generate heat, which will cause the relay to burn out.

Contents of the invention

Aiming at the deficiencies of the prior art, the object of the present invention is to propose a portable microcomputer charging protection device and method to achieve easy portability, short operation time of the device, convenient setting of fixed values, displayable information, uploadable fault recording, remote control and Administrative, incident recall and communication purposes.

A portable microcomputer charging protection device, which includes a protection case, a DC power supply terminal, a three-phase current input terminal, a trip switch, a DC switch, an integrated digital relay, a trip output terminal and an installation panel; wherein the installation The left side of the panel is provided with a DC power terminal and a three-phase current input terminal; Equipped with a trip switch;

The connection between the installation panel and the protection case is realized through a circle of metal corners set on the inner wall of the protection case; the DC power supply terminal is connected to the input terminal of the integrated digital relay through a DC switch; the trip output terminal is switched by a trip The chip is connected to the output end of the integrated digital relay; the three-phase current input terminal is connected to the input end of the integrated digital relay.

The protective case includes a case cover, a case body, a case lock and a handle. The case cover is provided with a lock head corresponding to the lock groove on the case body. When the lock head is opened, the case cover can be separated from the case body .

The protective case is treated by electrostatic spraying.

The material of the protective case adopts a metal plate capable of electrostatic shielding.

The installation panel is treated by electrostatic spraying.

An anti-vibration hemispherical sponge is arranged inside the box cover.

The method for carrying out current protection during charging by using a portable microcomputer charging protection device comprises the following steps:

Step 1. Initialize the integrated digital relay, and connect the grid voltage and current signal to the portable microcomputer charging protection device;

Step 2, the grid voltage and current signal is collected by the voltage and current converter in the integrated digital relay, after low-pass filtering, and then converted into a signal that meets the A/D conversion requirements through a multi-way switch, an operational amplifier and a limiter protector. The amplitude AC voltage signal is input to the single-chip microcomputer for processing by the digital quantity generated by A/D conversion;

Step 3. If the input current is greater than the operating current of the protection device, and the current duration reaches the protection action time, then perform step 4; otherwise, return to step 2;

Step 4. The protection device sends a trip signal and an alarm signal to the drive interface circuit in the integrated digital relay, and the drive interface circuit sends the above signal to the exit relay board, and the tripping and closing relay contacts on the exit relay board output the trip signal and trip The signal is sent to the circuit breaker trip circuit of the circuit under test through the trip output terminal; the alarm signal relay contact on the outlet relay board outputs an alarm signal, and the alarm signal is sent to the alarm circuit of the circuit under test through the trip output terminal; at the same time, The CPU in the integrated digital relay sends the status signal of the trip output terminal to the remote dispatching center of the circuit under test, and displays the status signal information of the trip output terminal on the LCD of the integrated digital relay.

The operating current range is 0.2 to 20 times the rated current, and the operating time range is 0s to 100s.

Advantages of the present invention:

(1) The charging protection device of the present invention includes a comprehensive digital relay, which is small in size and light in weight, and is easy to carry for testing;

(2) The inherent action time of the charging protection device of the present invention is close to 8mms, which makes the protection and fault removal time short, which is not suitable for causing power system shocks, and is conducive to the safe and stable operation of the power system;

(3) The minimum setting current of the charging protection device of the present invention is 0.2A, which meets the technical requirement that the minimum setting current of the first charging test of a 500kV transmission line is 0.3A;

(4) When setting the operating current and operating time of the charging protection device of the present invention, the operator only needs to operate the "key" on the integrated digital relay panel to select the menu command, input the set value, and display the fixed value through the LCD, so the setting of the fixed value is convenient and convenient. Accurate, digital display;

(5) The operating current and operating time of the charging protection device of the present invention have a large setting range, and the setting values are continuous values;

(6) The charging protection device of the present invention realizes remote "four-remote" communication with the microcomputer monitoring system of the power plant and substation, and the remote control center can know the charging protection action information in time;

(7) The operation mode of the charging protection device of the present invention can not only be set by four sets of trip switches, but also can be set by the comprehensive digital relay write protection (soft pressure plate), so it is flexible and reliable;

(8) The charging protection device of the present invention adopts a digital relay, so the power loss of the relay is small and does not generate heat.

Description of drawings

Fig. 1 is a schematic diagram of the device structure of an embodiment of the present invention, wherein (a) is a schematic diagram of the structure of the protection chassis, and (b) is a schematic diagram of the structure of the device inside the protection chassis;

Fig. 2 is an identification diagram of a device installation panel according to an embodiment of the present invention;

Fig. 3 is a schematic circuit diagram of an embodiment of the present invention;

Fig. 4 is a flowchart of a current protection method according to an embodiment of the present invention.

Detailed ways

Embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

As shown in (a) and (b) in Figure 1, a portable microcomputer charging protection device includes a protection case 1, a DC power supply terminal 2, a three-phase current input terminal 3, a trip switch 4, a DC switch 5. Integrated digital relay 6, trip output terminal 7 and installation panel 8; in the embodiment of the present invention, the two DC power supply terminals 2 and six three-phase current input terminals 3 are arranged on the left side of the installation panel 8; The eight tripping output terminals 7 are arranged on the right side; the integrated digital relay 6 is arranged in the middle, and the DC switch 5 is arranged below the integrated digital relay; two trip switching pieces 4 are respectively arranged on both sides of the DC switch 5 .

The connection between the installation panel 8 and the protection case 1 is realized by a circle of metal angles provided on the inner wall of the protection case 1; the DC power terminal 2 is connected to the input terminal of the integrated digital relay 6 through the DC switch 5; the tripping The output terminal 7 is connected to the output end of the integrated digital relay 6 through the trip switching piece 4 ; the three-phase current input terminal 3 is connected to the input end of the integrated digital relay 6 . The installation panel 8 is treated by electrostatic spraying.

As shown in (a) of Figure 1, the protective case 1 includes a case cover 1-1, a case body 1-2, a case lock 1-3 and a handle 1-4, and the case cover 1- 1 is provided with a lock head corresponding to the lock groove on the box body 1-2. When the lock head is opened, the box cover 1-1 can be separated from the box body 1-2; the protective box 1 is treated by electrostatic spraying, and the above-mentioned The protective case 1 is made of a metal plate capable of electrostatic shielding; the case cover 1-1 is provided with a shockproof hemispherical sponge. In the embodiment of the present invention, the external dimensions of the protective case 1 (in mmm) are: width×height×depth=415×300×315. Among them, the height of box 1-2 (excluding the box cover): 250mm (external dimension); the height of the box cover: 50mm (external dimension), lined with hemispherical black sponge (ethylene-vinyl acetate copolymer is a new type of environmentally friendly rubber and plastic material ) to achieve anti-slip, shock resistance, heat insulation, moisture resistance, and corrosion resistance; there is no hinge between the box cover 1-1 and the box body 1-2, and four box locks are installed. By opening the four box locks, the box cover 1- 1 is separated from the box body 1-2, and a gasket is provided between the box cover 1-1 and the box body 1-2 to realize sealing, dustproof and rainproof; four hemispherical stainless steel pad legs are installed at the bottom of the box body 1-2 , to achieve shock resistance; a handle 1-4 is installed on the cabinet 1-2, and the handle 1-4 is close to the cabinet 1-2 when not in use; each side of the cabinet 1 is protected with 20mm×20mm, 1.0mm thick aluminum Corner wrapping to protect the corners of the chassis 1 with stainless steel corners; from the upper edge of the box 1-2 to the bottom 3.0mm, a circle of 15mm×15mm and 2.0mm thick aluminum corners are inlaid along the inner wall of the box 1-2. Four M3.7 holes are symmetrically drilled on the corners and tapped to fix the panel 8; the material of the box body 1-2 and the box cover 1-1: 2.0mm thick aluminum plate, which realizes electrostatic shielding and portability; the whole protection The chassis 1 is electrostatically sprayed to achieve corrosion resistance.

The DC power terminal 2 (1 red, 1 black) is externally connected to a 110-220V DC power supply, which is used as the working power supply of the integrated digital relay 6 . The DC switch 5 is used as the working power switch of the integrated digital relay 6 . The three-phase current input terminals 3 (2 yellow, 2 green and 2 red) lead to the three-phase current output by the current transformer of the transmission line as the input current of the integrated digital relay 6 . Integrated digital relay 6 (model PA140-F1) is composed of main control board, man-machine interface board, bus board, power board, current transformer board, relay board, shell and wiring terminals to realize charging protection function and to monitor power transmission Integrity of line and equipment insulation performance. The trip switch 4 is used as the operating mode setting element of the microcomputer charging protection device. When the "trip 1" switch is set to the "switching" position, the integrated digital relay 6 "trip 1" exit is put into operation; when the "trip 1" switch is set In the "back" position, the integrated digital relay 6 "trip 1" exit is out of operation. The purpose of the other "Trip" switches is similar to that of the "Trip 1" switch. Trip output terminals 7 (black 8 pieces) are connected to the trip circuits of the four groups of circuit breakers in the system under test. When the integrated digital relay 6 operates, the trip switches 4 are all set to the "switching" position, and the "portable microcomputer charging protection device" Output four sets of trip commands.

As shown in Figure 2, insert four trip switching pieces 4 (model JY1-3) into the round holes marked "Switching, Retreating" on the installation panel, and fix them with their own standard parts. The three conductive rods of the sheet should be insulated from the installation panel 8; insert a red terminal (model JXZ-1/1) at the mark "DC+", and insert a black terminal (model JXZ-1/1) at the mark "DC-" is JXZ-1/1); at the mark "IA, Ia", insert two yellow terminals (model is JXZ-1/1); at the mark "IB, Ib", insert two green terminals (model is JXZ-1/1); at the mark "IC, Ic", insert two red terminals (model is JXZ-1/1); at the mark "trip 1, trip 2, trip 3, trip 4", Insert eight black terminal posts (model JXZ-1/1); and fix them with their own standard parts. The conductive rods of all terminal posts should be insulated from the installation panel 8; insert a comprehensive The digital relay 6 (model PA140-F1) is fixed with two brackets (each bracket is inserted into the installation track, one end is against the installation panel 8, and the other end is fixed on the relay 6). Insert the DC switch 5 (model KCD-102) into the rectangular hole of 20×26.8, and fix it by itself.

As shown in Fig. 3, adopt yellow BVR-2.5mm wire in the embodiment of the present invention to connect the yellow binding post identified as IA with the X4-1 terminal of integrated digital relay 6; adopt yellow BVR-2.5mm wire to be identified as Ia The yellow binding post of the integrated digital relay 6 is connected to the X4-2 terminal. Use the green BVR-2.5mm2 wire to connect the green terminal marked as IB to the X4-3 terminal of the integrated digital relay 6; use the green BVR-2.5mm2 wire to connect the green terminal marked as Ib to the X4 of the integrated digital relay 6 -4 terminal block connections. Use a red BVR-2.5mm2 wire to connect the red terminal marked as IC to the X4-5 terminal of the integrated digital relay 6; use a red BVR-2.5mm2 wire to connect the red terminal marked as Ic to the X4 of the integrated digital relay 6 -6 terminal block connections. Use a red BVR-1.5mm2 wire to connect the red terminal marked DC+ to the terminal 1 of the DC switch QF; use a red BVR-1.5mm2 wire to connect the X5-1 terminal of the integrated digital relay 6 to the terminal 1 of the DC switch QF 2 connection; use a black BVR-1.5mm2 wire to connect the black terminal marked DC- to the terminal 3 of the DC switch QF; use a black BVR-1.5mm2 wire to connect the X5-2 terminal of the integrated digital relay 6 to the DC switch Terminal 4 of the QF is connected. Use a black BVR-1.5mm2 wire to connect the black terminal marked "trip 1" to terminal 2 of the "trip 1" switching piece XB1; use a black BVR-1.5mm2 wire to connect the terminal X5-4 of the integrated digital relay 6 Connect with terminal 1 of "trip 1" switching piece XB1; use black BVR-1.5mm2 wire to connect terminal X5-5 of integrated digital relay 6 to another black terminal marked "trip 1". Use a black BVR-1.5mm2 wire to connect the black terminal marked as "trip 2" to terminal 2 of the "trip 2" switching piece XB2; use a black BVR-1.5mm2 wire to connect the terminal X2-1 of the integrated digital relay 6 Connect with terminal 1 of "trip 2" switching piece XB2; use black BVR-1.5mm2 wire to connect terminal X2-2 of integrated digital relay 6 to another black terminal marked "trip 2". Use a black BVR-1.5mm2 wire to connect the black terminal marked "trip 3" to terminal 2 of the "trip 3" switching piece XB3; use a black BVR-1.5mm2 wire to connect the terminal X2-5 of the integrated digital relay 6 Connect with terminal 1 of "trip 3" switching piece XB3; use black BVR-1.5mm2 wire to connect terminal X2-6 of integrated digital relay 6 to another black terminal marked "trip 3". Use a black BVR-1.5mm2 wire to connect the black terminal marked "trip 4" to terminal 2 of the "trip 4" switching piece XB4; use a black BVR-1.5mm2 wire to connect the terminal X5-6 of the integrated digital relay 6 Connect with terminal 1 of "trip 4" switching piece XB4; use black BVR-1.5mm2 wire to connect terminal X5-7 of integrated digital relay 6 to another black terminal marked "trip 4".

The working power supply voltage of the embodiment of the present invention is: DC 110-220V. Input rated current: In=1A or 5A; charging protection "tripping relay" contact: DC220V, 5~8A; charging protection "action signal relay" contact: DC220V, 5A.

The current protection method using a portable microcomputer charging protection device, as shown in Figure 4, includes the following steps:

The method for carrying out current protection by using a portable microcomputer charging protection device comprises the following steps:

Step 1. Initialize the integrated digital relay, and connect the grid voltage and current signal to the portable microcomputer charging protection device;

Step 2, the grid voltage and current signal is collected by the voltage and current converter in the integrated digital relay, after low-pass filtering, and then converted into a signal that meets the A/D conversion requirements through a multi-way switch, an operational amplifier and a limiter protector. The amplitude AC voltage signal is input to the single-chip microcomputer for processing by the digital quantity generated by A/D conversion;

Step 3. If the input current is greater than the operating current of the protection device, the operating current range described in this embodiment is 0.3-0.5A, and the duration of the current reaches the operating time of the protection, and the operating time range described in this embodiment is 0ms ~80ms, then execute step 4; if the input current is less than the action current of the protection device, and the current duration does not reach the protection action time, return to step 2;

Step 4. The protection device sends a trip signal and an alarm signal to the drive interface circuit in the integrated digital relay, and the drive interface circuit sends the above signal to the exit relay board, and the tripping and closing relay contacts on the exit relay board output the trip signal and trip The signal is sent to the circuit breaker trip circuit of the circuit under test through the trip output terminal; the alarm signal relay contact on the outlet relay board outputs an alarm signal, and the alarm signal is sent to the alarm circuit of the circuit under test through the trip output terminal; at the same time, The CPU in the integrated digital relay sends the status signal of the trip output terminal to the remote dispatching center of the circuit under test, and displays the status signal information of the trip output terminal on the LCD of the integrated digital relay.

The embodiment of the present invention can realize the following functions:

(1) Realize the function of two-stage current protection (current quick break and time-limited current quick break protection). The voltage and current signal input from the primary equipment transformer of the power grid is collected by the voltage and current converter of the integrated digital relay 6, filtered by a low-pass filter, and then transformed into an A/D Convert the AC voltage signal of the required amplitude, and the digital quantity generated by A/D conversion is processed by the single-chip microcomputer. When the input current is greater than the action current of the protection device, and the current duration reaches the protection action time, the protection device sends a trip signal and an alarm signal to the drive interface circuit in the integrated digital relay 6, and the drive interface circuit sends the above signals to the exit On the relay board, the tripping and closing relay contacts on the outlet relay board output trip signals, which are sent to the circuit breaker trip circuit of the circuit under test through the trip output terminals; the alarm signal relay contacts on the outlet relay board output alarm signals , the alarm signal is sent to the alarm circuit of the circuit under test through the trip output terminal; at the same time, the CPU in the integrated digital relay sends a status signal of the trip output terminal to the remote dispatching center of the circuit under test, and the integrated digital relay 6 LCD display The screen displays the status signal information of the trip output terminal.

The two-stage current protection adopts the Fourier algorithm.

Decompose a periodic current function i(t) into an infinite series of DC components, fundamental waves and harmonics:

$\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, ω ₁ is the fundamental angular frequency;

t is time;

n is the number of harmonics;

a _n and b _n represent the magnitudes of the nth harmonic sine and cosine terms respectively.

because $a_{\mathrm{no}}=\frac{2}{T}{\&Integral;}_0^{T}i\left(t\right)\sin \left(\mathrm{no}{\mathrm{\&omega;}}_{1}t\right)\mathrm{dt},$ $b_{\mathrm{no}}=\frac{2}{T}{\&Integral;}_0^{T}i\left(t\right)\cos \left(\mathrm{no}{\mathrm{\&omega;}}_{1}t\right)\mathrm{dt},$ Among them, T is the period; then the effective value of the nth harmonic current component is The effective value of the fundamental current component is

The criterion of the two-stage current protection is: I ₁ >I _dz , t ₁ >t _dz . Among them, I ₁ is the effective value of the fundamental current input to the portable microcomputer charging protection device, I _dz is the operating current value; t ₁ is the duration of I ₁ current, and t _dz is the operating time of the portable microcomputer charging protection device. When this criterion is met, the portable microcomputer charging protection device will act.

(2) Control function. The device of this embodiment operates the "closing" control key or the "opening" control key on the integrated digital relay 6, and the CPU in the integrated digital relay 6 sends corresponding control commands, and the trip, closing signals and alarm signals are sent to The drive interface circuit sends these signals to the exit relay board, and the tripping and closing relay contacts on the exit relay board are connected to the tripping and closing circuit of the primary circuit breaker of the power grid under test through the trip output terminal, so that Opening and closing operation of the circuit breaker realizes the remote control function.

(3) Measurement function. The input voltage and current signal is sampled and low-pass filtered by the voltage and current converter in the integrated digital relay, and then amplified by a multi-channel switch and an operational amplifier to convert it into an AC voltage signal with an amplitude that meets the A/D conversion requirements. /D conversion generates digital quantities, which can measure the three-phase phase voltage, three-phase line voltage, current, power factor, frequency, etc.

(4) Remote device management function. The device in this embodiment can communicate with the remote dispatching center through the photoelectrically isolated serial communication RS485/RS422 interface of the integrated digital relay 6, and realize remote control, remote signaling, remote adjustment, telemetry, protection of remote input and withdrawal, fault recording and uploading, etc. Function. The CPU in the integrated digital relay 6 can accept photoelectrically isolated pulse signals, remote control input signal quantities, and input signal quantities generated by operations such as keyboard query and setting values.

(5) Communication function. The device in this embodiment adopts RS485/RS422 communication interface to communicate with the main control computer, so as to realize remote transmission and exchange of information. Through the main control computer, the remote query and setting functions of the protection device's fixed value and the remote control function of the device can be realized.

(6) Event memory function. The device in this embodiment can automatically record the occurrence time, type and action value of the event through the integrated digital relay 6 . The resolution of its event record is less than 2 milliseconds, and it has the function of not losing power when power off.

(7) Display function. All the signal measurements, protection action values, tripping and closing displacement records, setting process, query process, fault type, remote signal amount, grid frequency, time, etc. obtained by the detection of this embodiment can be recorded in the integrated digital relay 6 of this device. displayed on the LCD.

(8) Fault recording upload function. The RS485/RS422 communication interface of the integrated digital relay 6 of the device in this embodiment is used to realize the fault recording and uploading function, which can record the current and voltage waveforms during faults and upload them to the PC for display. This provides detailed information for monitoring system operation and analyzing accident causes.

(9) Clock function. The RS485/RS422 communication interface of the comprehensive digital relay 6 of the device of this embodiment is used to connect with the upper computer to realize the automatic time synchronization and display functions of the clock.

Claims (7)

1. A portable microcomputer charging protection device, characterized in that: the device includes a protection case (1), a DC power terminal (2), a three-phase current input terminal (3), a trip switch (4), a DC switch (5), integrated digital relay (6), trip output terminal (7) and installation panel (8); the left side of the installation panel (8) is provided with a DC power supply terminal (2) and three-phase current input terminal (3); the right side is provided with a tripping output terminal (7); a comprehensive digital relay (6) is provided in the middle, and a DC switch (5) is provided below the comprehensive digital relay; the DC switch (5) has two The side is provided with a trip switching piece (4); The connection between the installation panel (8) and the protection case (1) is realized through a circle of metal corners provided on the inner wall of the protection case (1); the DC power terminal (2) is connected to the integrated digital The input terminal of the relay (6); the trip output terminal (7) is connected to the output terminal of the integrated digital relay (6) through the trip switch (4); the three-phase current input terminal (3) is connected to the integrated The input terminal of the digital relay (6); The protective case (1) includes a case cover (1-1), a case body (1-2), a case lock (1-3) and a handle (1-4), and the case cover (1- 1) A lock head corresponding to the lock groove on the box body (1-2) is provided on the top, and the box cover (1-1) can be separated from the box body (1-2) when the lock head is opened; The integrated digital relay (6) adopts the model PA140-F1, and the DC switch (5) adopts the model KCD-102. 2. The portable microcomputer charging protection device according to claim 1, characterized in that: the protection case (1) is treated by electrostatic spraying. 3. The portable microcomputer charging protection device according to claim 1, characterized in that: the protection case (1) is made of a metal plate capable of electrostatic shielding. 4. The portable microcomputer charging protection device according to claim 1, characterized in that: the installation panel (8) is treated by electrostatic spraying. 5. The portable microcomputer charging protection device according to claim 2, characterized in that: a shockproof hemispherical sponge is arranged inside the box cover (1-1). 6. The method for carrying out current protection during the charging process by using the portable microcomputer charging protection device according to claim 1, characterized in that: comprising the following steps: Step 1. Initialize the integrated digital relay, and connect the grid voltage and current signal to the portable microcomputer charging protection device; Step 2, the grid voltage and current signal is collected by the voltage and current converter in the integrated digital relay, after low-pass filtering, and then converted into a signal that meets the A/D conversion requirements through a multi-way switch, an operational amplifier and a limiter protector. The amplitude AC voltage signal is input to the single-chip microcomputer for processing by the digital quantity generated by A/D conversion; Step 3. If the input current is greater than the operating current of the protection device, and the current duration reaches the protection action time, then perform step 4; otherwise, return to step 2; Step 4. The protection device sends a trip signal and an alarm signal to the drive interface circuit in the integrated digital relay, and the drive interface circuit sends the above signal to the exit relay board, and the tripping and closing relay contacts on the exit relay board output the trip signal and trip The signal is sent to the circuit breaker trip circuit of the circuit under test through the trip output terminal; the alarm signal relay contact on the outlet relay board outputs an alarm signal, and the alarm signal is sent to the alarm circuit of the circuit under test through the trip output terminal; at the same time, The CPU in the integrated digital relay sends the status signal of the trip output terminal to the remote dispatching center of the circuit under test, and displays the status signal information of the trip output terminal on the LCD of the integrated digital relay. 7 . The charging current protection method for a portable microcomputer according to claim 6 , wherein the operating current range is 0.2 to 20 times the rated current, and the operating time range is 0 s to 100 s.