CN202353175U - Overvoltage and undervoltage protection system for three-phase power system - Google Patents

Abstract

The utility model proposes an overvoltage and undervoltage protection system for a three-phase power supply system. The system includes: a rectification unit, a sampling unit, an undervoltage judgment unit, an undervoltage delay unit, an overvoltage judgment unit, an overvoltage delay unit, a circuit breaker trigger unit and a first signal isolation and OR unit. Wherein, the first signal isolation and OR unit is used to isolate the sampling voltage signal corresponding to each phase voltage output obtained by the sampling unit, and output the sampling voltage signal with the highest voltage value; the overvoltage The judging unit is used to compare the sampling voltage signal output by the first signal isolation, OR unit with the obtained overvoltage reference signal, where the sampling voltage signal output by the first signal isolation, OR unit is higher than the When the reference signal is overvoltage, the overvoltage signal is output. In the utility model, since only one channel of sampling voltage signal needs to be judged for overvoltage, the cost of the overvoltage and undervoltage protection system is reduced.

Description

Overvoltage and undervoltage protection system for three-phase power system

technical field

The utility model relates to the field of power supply for power distribution systems, in particular to an overvoltage and undervoltage protection system for a three-phase power supply system.

Background technique

In the practical application of industry and household, the three-phase power system is susceptible to overvoltage or undervoltage due to the influence of external factors, and the occurrence of overvoltage or undervoltage may cause certain damage to the load and cause Certain economic losses. Therefore, when an overvoltage or undervoltage occurs in the three-phase power system, it is necessary to use a circuit breaker or the like to cut off the path of the three-phase power system to protect the circuit.

Fig. 1 shows a general structural diagram of an overvoltage and undervoltage protection system for a three-phase power system. As shown in Figure 1, the system mainly includes: a DC power supply unit 10, a rectification unit 20, a sampling unit 30, an overvoltage judging unit 40, an overvoltage delay unit 50, an undervoltage judging unit 60, an undervoltage delay unit 70 and a circuit breaker Trigger unit 80.

Wherein, the DC power supply unit 10 is used for stepping down and stabilizing the voltage output of a certain phase of the three-phase power supply system, and generating a stable DC power supply. In actual implementation, the DC power supply unit 10 can also step down and stabilize the voltage output of a certain phase of the three-phase power supply system processed by the rectification unit 20, and generate a stable DC power supply. Alternatively, the DC power supply unit can also be generated by other means, such as batteries.

The rectification unit 20 is used to respectively rectify the voltage output of each phase of the three-phase power system, and obtain a DC voltage output corresponding to each phase voltage output.

The sampling unit 30 is used to respectively perform step-down or step-down delay processing on the rectified DC voltage output of each phase to obtain a sampled voltage signal corresponding to each phase voltage output.

The overvoltage judging unit 40 is powered by the DC power supply unit 10, and is used for comparing the currently input one-phase sampled voltage signal with the obtained overvoltage reference signal, and when the currently input sampled voltage signal is higher than the overvoltage reference signal , output overvoltage signal.

The overvoltage delay unit 50 is used to delay the output of the output of the overvoltage judging unit 40 for a first set time, and the time when the overvoltage judging unit 40 outputs an overvoltage signal reaches the first set time , a trigger signal is output to control the circuit breaker trigger unit 80 to trigger the conduction of the circuit breaker coil in the three-phase power system loop, so that the circuit breaker is disconnected.

The undervoltage judging unit 60 is powered by the DC power supply unit 10, and is used to compare the currently input one-phase sampled voltage signal with the obtained undervoltage reference signal, and when the currently input sampled voltage signal is lower than the undervoltage reference signal , output undervoltage signal.

The undervoltage delay unit 70 is used to delay the output of the output of the undervoltage judgment unit 60 for a second set time, and the time when the undervoltage judgment unit 60 outputs the undervoltage signal reaches the second set time , a trigger signal is output to control the circuit breaker trigger unit 80 to trigger the conduction of the circuit breaker coil in the three-phase power system loop, so that the circuit breaker is disconnected.

At present, when realizing the above-mentioned overvoltage and undervoltage protection system of the three-phase power supply system, the cost is generally high.

Contents of the invention

The utility model provides an overvoltage and undervoltage protection system for a three-phase power supply system, which is used to reduce the cost of the overvoltage and undervoltage protection system of the three-phase power supply system.

The utility model provides an overvoltage and undervoltage protection system for a three-phase power supply system. The overvoltage and undervoltage protection system can generate an undervoltage reference signal and an overvoltage reference signal; the system includes: a rectification unit, a sampling unit, an undervoltage judgment unit, an undervoltage delay unit, an overvoltage judgment unit, an overvoltage delay unit, a circuit breaker trigger unit, and a first signal isolation and OR unit, wherein;

The rectification unit is used to convert the voltage output of each phase of the three-phase power system from AC to DC for output;

The sampling unit is used to sample each phase voltage output of the three-phase power system rectified by the rectification unit, and output a sampled voltage signal corresponding to each phase voltage output;

The undervoltage judging unit is used to compare the currently input one-phase sampling voltage signal with the undervoltage reference signal, and output an undervoltage signal when the currently input sampling voltage signal is lower than the undervoltage reference signal;

The undervoltage delay unit is used to output a trigger signal to the circuit breaker trigger unit when the time when the undervoltage judging unit outputs the undervoltage signal reaches a second set time;

The first signal isolation and OR unit is used to isolate the sampling voltage signal corresponding to each phase voltage output obtained by the sampling unit, and output the sampling voltage signal with the highest voltage value among them;

The overvoltage judging unit is used to compare the sampling voltage signal output by the first signal isolation, OR unit with the overvoltage reference signal, and the sampling voltage signal output by the first signal isolation, OR unit outputting an overvoltage signal when it is higher than the overvoltage reference signal;

The overvoltage delay unit is used to output a trigger signal to the circuit breaker trigger unit when the time when the overvoltage judging unit outputs the overvoltage signal reaches a first set time;

The circuit breaker triggering unit is used to trigger the conduction of the circuit breaker coil in the three-phase power system loop when receiving the trigger signal output by the undervoltage delay unit or the overvoltage delay unit, so that the circuit breaker is turned off. open.

In one embodiment of the present invention, the first signal isolation and OR unit includes: a first pull-down resistor and three first diodes, and the anode of each first diode is connected to one phase of the sampling unit. The output ends are connected, and the negative poles are connected together to serve as the output of the first signal, isolated NOR unit; one end of the first pull-down resistor is connected to the negative poles of the three first diodes, and the other end is grounded.

Preferably, the system further includes: a second signal isolation and OR unit, which is used to isolate and concentrate the outputs of the undervoltage delay unit and the overvoltage delay unit to one point, and any one of them When the output is a trigger signal, output the trigger signal to the circuit breaker trigger unit;

The circuit breaker trigger unit includes: a first voltage regulator tube, a silicon controlled rectifier and a first capacitor; the positive pole of the first voltage regulator tube is connected to the output terminal of the second signal isolation and OR unit, and the negative pole is connected to the output terminal of the second signal isolation and OR unit. The gate of the thyristor is connected, one main terminal of the thyristor is connected to the circuit breaker coil in the three-phase power system circuit, and the other main terminal is grounded, and one end of the first capacitor is connected to the first stable The negative pole of the pressure tube is connected, and the other end is grounded.

In one embodiment of the present invention, the second signal isolation and OR unit includes: a second pull-down resistor and a plurality of outputs consistent with the output of the undervoltage delay unit and the overvoltage delay unit The second diode, the anode of each second diode is connected to the output terminal of the corresponding undervoltage delay unit or overvoltage delay unit, and the negative poles are connected together as the output terminal of the second signal isolation and OR unit It is connected to the input end of the circuit breaker trigger unit; one end of the second pull-down resistor is connected to the cathodes of the plurality of second diodes connected together, and the other end is grounded.

In one embodiment of the present invention, the undervoltage judging unit includes: three undervoltage judging subunits, and each undervoltage judging subunit is used to compare the one-phase sampling voltage signal output by the sampling unit with the undervoltage judging subunit. Compared with the voltage reference signal, when the sampled voltage signal of the phase is lower than the under-voltage reference signal, output the under-voltage signal corresponding to the phase;

The undervoltage delay unit includes: three undervoltage delay subunits, and each undervoltage delay subunit corresponds to the output of an undervoltage judgment subunit.

In one embodiment of the present invention, the undervoltage judging unit includes: an undervoltage judging subunit for isolating the first signal, taking the sampling voltage signal output by the OR unit, and the undervoltage reference signal performing a comparison, and outputting an undervoltage signal when the sampling voltage signal output by the first signal isolation and OR unit is lower than the undervoltage reference signal;

The undervoltage delay unit includes: an undervoltage delay subunit corresponding to the undervoltage judgment subunit.

Wherein, the overvoltage delay unit is an RC delay circuit, or an RC delay control circuit with a MOS tube;

The undervoltage delay unit is an RC delay circuit, or an RC delay control circuit with a MOS tube.

In one embodiment of the present utility model, the RC delay control circuit with a MOS tube includes:

The fourth diode, the second voltage limiting resistor, the second charge and discharge capacitor, the second charge and discharge resistor, the second voltage regulator tube and the first MOS tube; the anode of the fourth diode and the corresponding overvoltage judgment The output end of the unit or the undervoltage judgment unit is connected, and the negative pole is connected to one end of the second voltage limiting resistor; the other end of the second voltage limiting resistor is connected to one end of the second charging and discharging capacitor; the second The other end of the charging and discharging capacitor is grounded, and the second charging and discharging resistor is connected in parallel with the second charging and discharging capacitor; The gate of the first MOS transistor is connected; the drain of the first MOS transistor is connected to the anode of the fourth diode, and the source is the output end of the overvoltage delay unit or the undervoltage delay unit;

Alternatively, the RC delay control circuit with a MOS tube includes: a first RC delay circuit, a controllable switch and a second MOS tube;

The input end of the first RC delay circuit is connected to the output end of the corresponding overvoltage judgment unit or undervoltage judgment unit, the output end of the first RC delay circuit is connected to the control end of the controllable switch, One connection terminal of the controllable switch is connected to the DC power supply, and the other connection terminal is grounded; the control terminal of the MOS tube is connected to the output terminal of the undervoltage judgment unit or the overvoltage judgment unit, the drain is connected to the DC power supply, and the source It is the output end of the over-voltage delay unit or the under-voltage delay unit.

In one embodiment of the present invention, the first RC delay circuit includes: a first triode, a third charge and discharge capacitor, a third voltage limiting resistor, a second triode, a fourth voltage limiting resistor, The fourth charging and discharging capacitor, the third charging and discharging resistor, the fifth diode and the second voltage regulator tube; the base of the first triode is connected to the output terminal of the corresponding overvoltage judging unit or undervoltage judging unit , the collector is connected to the DC power supply, the emitter is connected to one end of the third charge and discharge capacitor; the other end of the third charge and discharge capacitor is grounded; one end of the third voltage limiting resistor is connected to the first triode The emitter is connected, and the other end is connected with the base of the second triode; the collector of the second triode is connected with one end of the fourth voltage limiting resistor, and the emitter is connected with one end of the fourth charging and discharging capacitor; The other end of the fourth voltage limiting resistor is connected to a DC power supply; the other end of the fourth charging and discharging capacitor is grounded; the third charging and discharging resistor is connected in parallel with the fourth charging and discharging capacitor; the fifth diode The anode of the positive pole is connected to the non-ground terminal of the third charging and discharging resistor, and the negative pole is connected to the positive pole of the second voltage stabilizing tube; the negative pole of the second voltage stabilizing tube is the output end of the first RC delay circuit .

In one embodiment of the present invention, the controllable switch includes: a third transistor, a fifth voltage limiting resistor, a fourth transistor and a sixth voltage limiting resistor; the base of the third transistor pole is connected with the output terminal of the first RC delay circuit; the emitter of the third transistor is grounded, the collector is connected with the base of the fourth transistor and one end of the fifth voltage limiting resistor; The other end of the fifth voltage limiting resistor is connected to the DC power supply; the emitter of the fourth triode is grounded, and the collector is connected to one end of the sixth voltage limiting resistor; the other end of the sixth voltage limiting resistor is connected to the DC power is connected.

In one embodiment of the present utility model, the DC power supply is generated by dividing and stabilizing the voltage output of a certain phase of the three-phase power supply system.

As can be seen from the above scheme, since the utility model uses the first signal isolation and OR unit to isolate the sampling voltage signals corresponding to each phase voltage output obtained by the sampling unit, and output the sampling voltage with the highest voltage value among them signal, so the overvoltage judging unit may include only one op amp or not, such as other circuits that implement a comparison function, and are used to isolate the first signal according to the overvoltage reference signal, and perform the sampling voltage signal output by the OR unit. The overvoltage judgment reduces the number of at least two operational amplifiers and reduces the cost of the overvoltage and undervoltage protection system of the three-phase power supply system.

Further, by using the second signal isolation and OR unit to isolate the outputs of the undervoltage delay unit and the overvoltage delay unit and concentrate them at one point, when any one of the outputs is a trigger signal, the trigger signal is output to all The above circuit breaker trigger unit, so that the circuit breaker trigger unit only includes an operational amplifier or does not include an operational amplifier, further reducing the cost of the overvoltage and undervoltage protection system of the three-phase power supply system.

In addition, by making the undervoltage judging unit also receive the sampling voltage signal output by the first signal isolation and OR unit, the undervoltage judging unit may only include one operational amplifier or not include an operational amplifier, such as other circuit, thereby also reducing the number of operational amplifiers in the undervoltage judging unit, and further reducing the cost of the overvoltage and undervoltage protection system of the three-phase power supply system.

In addition, by using a delay circuit with a MOS tube in the under-voltage delay unit and the over-voltage delay unit, the AND logic of the delay output and the output of the under-voltage judgment unit or the over-voltage judgment unit can be realized, thereby avoiding the error of misoperation produce.

Description of drawings

Preferred embodiments of the present utility model will be described in detail below with reference to the accompanying drawings, so that those of ordinary skill in the art are more aware of the above-mentioned and other features and advantages of the present utility model. In the accompanying drawings:

FIG. 1 is a general structural diagram of an overvoltage and undervoltage protection system for a three-phase power system.

FIG. 2 is a schematic structural diagram of an overvoltage and undervoltage protection system of a three-phase power supply system in current application.

FIG. 3 is a schematic structural diagram of an overvoltage and undervoltage protection system of a three-phase power supply system in an embodiment of the present invention.

Fig. 4 is a schematic structural diagram of an overvoltage and undervoltage protection system of a three-phase power supply system in another embodiment of the present invention.

FIG. 5 is a schematic structural diagram of an overvoltage and undervoltage protection system of a three-phase power supply system in another embodiment of the present invention.

Fig. 6 is a schematic diagram of the internal structure of the overvoltage delay unit in the present invention.

FIG. 7 is a schematic structural diagram corresponding to an overvoltage and undervoltage protection system of a three-phase power system in an example of the embodiment shown in FIG. 4 .

FIG. 8 is a schematic structural diagram of another specific implementation of the overvoltage delay subunit in the example shown in FIG. 6 .

In the figure: 10-DC power supply unit 20-rectification unit 30-sampling unit 40-overvoltage judgment unit 50-overvoltage delay unit 60-undervoltage judgment unit 70-undervoltage delay unit 80-circuit breaker trigger unit 90-first Signal isolation and OR unit 100-the second signal isolation, OR unit

201-First phase rectification subunit 202-Second phase rectification subunit 203-Third phase rectification subunit

301-first phase sampling subunit 302-second phase sampling subunit 303-third phase sampling subunit

401-first phase overvoltage judgment subunit 402-second phase overvoltage judgment subunit 403-third phase overvoltage judgment subunit 404-overvoltage judgment subunit

501-First phase overvoltage delay subunit 502-Second phase overvoltage delay subunit 503-Third phase overvoltage delay subunit 504-Overvoltage delay subunit

601-First phase undervoltage judgment subunit 602-Second phase undervoltage judgment subunit 603-Third phase undervoltage judgment subunit 604-Undervoltage judgment subunit

701-First phase undervoltage delay subunit 702-Second phase undervoltage delay subunit 703-Third phase undervoltage delay subunit 704-Undervoltage delay subunit

801-Overvoltage delay trigger unit with operational amplifier 802-Undervoltage delay trigger unit with operational amplifier 803-Voltage regulator conduction trigger unit

5041-The first RC delay circuit

Detailed ways

The purpose, technical scheme and advantages of the utility model are more clear, and the following examples are given to further describe the utility model in detail.

Fig. 2 shows a schematic structural diagram of an overvoltage and undervoltage protection system of a three-phase power supply system in current application. As shown in Figure 2, the rectification unit 20, the sampling unit 30, the overvoltage judgment unit 40, the overvoltage delay unit 50, the undervoltage judgment unit 60 and the undervoltage delay unit 70 in the system respectively include three corresponding subunits, Each subunit corresponds to a phase voltage output of a three-phase power system. In addition, the circuit breaker trigger unit 80 includes: an overvoltage delay trigger unit 801 with an operational amplifier and an undervoltage delay trigger unit 802 with an operational amplifier.

Wherein, the rectification unit 20 includes a first phase rectification subunit 201 , a second phase rectification subunit 202 and a third phase rectification subunit 203 . Among them, the first phase rectification subunit 201 is used to rectify the first phase voltage output of the three-phase power system, and obtain the first phase DC voltage output corresponding to the first phase voltage output; the second phase rectification subunit 202 is used for Rectify the second-phase voltage output of the three-phase power supply system, and obtain the second-phase DC voltage output corresponding to the second-phase voltage output; the third-phase rectification subunit 203 is used to output the third-phase voltage of the three-phase power supply system performing rectification, and obtaining a third-phase DC voltage output corresponding to the third-phase voltage output.

The sampling unit 30 includes a first phase sampling subunit 301 , a second phase sampling subunit 302 and a third phase sampling subunit 303 . Among them, the first phase sampling subunit 301 is used to step down or step down and delay the rectified first phase DC voltage output to obtain the first phase sampling voltage signal corresponding to the first phase voltage output; the second phase sampling The sub-unit 302 is used to step down or step-down delay the rectified second-phase DC voltage output to obtain a second-phase sampling voltage signal corresponding to the second-phase voltage output; the third-phase sampling sub-unit 303 is used to Step-down or step-down delay processing is performed on the rectified third-phase DC voltage output to obtain a third-phase sampled voltage signal corresponding to the third-phase voltage output.

The overvoltage judging unit 40 includes a first phase overvoltage judging subunit 401 , a second phase overvoltage judging subunit 402 and a third phase overvoltage judging subunit 403 respectively powered by the DC power supply unit 10 . Wherein, the first phase overvoltage judging subunit 401 includes a first operational amplifier (op amp for short), which is used to compare the first phase sampled voltage signal with the obtained overvoltage reference signal, and when the first phase sampled voltage signal is higher than When the overvoltage reference signal is used, the output represents the high level of the first phase overvoltage signal; the second phase overvoltage judging subunit 402 includes a second op amp for combining the second phase sampling voltage signal with the obtained overvoltage reference signal Compare, and when the second phase sampling voltage signal is higher than the overvoltage reference signal, output a high level representing the second phase overvoltage signal; the third phase overvoltage judging subunit 403 includes a third operational amplifier for The third phase sampled voltage signal is compared with the obtained overvoltage reference signal, and when the third phase sampled voltage signal is higher than the overvoltage reference signal, a high level representing the third phase overvoltage signal is output. Wherein, the overvoltage reference signal can be generated by dividing the voltage of the DC power supply unit 10 by using a voltage dividing resistor.

The overvoltage delay unit 50 includes a first phase overvoltage delay subunit 501 , a second phase overvoltage delay subunit 502 and a third phase overvoltage delay subunit 503 . Wherein, the first phase overvoltage delay subunit 501 is used to delay the output of the first phase overvoltage judgment subunit 401 for a first set time, and in the first phase overvoltage judgment subunit 401 When the time of outputting the high level reaches the first set time, control the overvoltage delay trigger unit 801 with an operational amplifier to trigger the circuit breaker to disconnect; the second phase overvoltage delay subunit 502 is used to control the first phase The output of the two-phase overvoltage judging subunit 402 is delayed for the first set time, and when the time when the second phase overvoltage judging subunit 402 outputs a high level reaches the first set time, the control The overvoltage delay trigger unit 801 with an operational amplifier triggers the disconnection of the circuit breaker; the third phase overvoltage delay subunit 503 is used to determine the output of the third phase overvoltage judgment subunit 403 for the first set time Delayed output, when the time when the third phase overvoltage judging subunit 403 outputs a high level reaches the first set time, output a high level indicating a trigger signal to control the overvoltage delay of the band op amp The trigger unit 801 triggers the conduction of the circuit breaker coil in the three-phase power system circuit, so that the circuit breaker is disconnected.

The undervoltage judging unit 60 includes a first phase undervoltage judging subunit 601 , a second phase undervoltage judging subunit 602 and a third phase undervoltage judging subunit 603 respectively powered by the DC power supply unit 10 . Wherein, the first phase undervoltage judging subunit 601 includes a fourth operational amplifier, which is used to compare the first phase sampling voltage signal with the obtained undervoltage reference signal, and when the first phase sampling voltage signal is lower than the undervoltage reference signal , the output represents the high level of the first phase undervoltage signal; the second phase undervoltage judging subunit 602 includes a fifth operational amplifier, which is used to compare the second phase sampling voltage signal with the obtained undervoltage reference signal. When the two-phase sampling voltage signal is lower than the undervoltage reference signal, the output represents the high level of the second phase undervoltage signal; the third phase undervoltage judging subunit 603 includes a sixth operational amplifier for converting the third phase sampling voltage signal Compared with the obtained undervoltage reference signal, when the third phase sampled voltage signal is lower than the undervoltage reference signal, a high level indicating the third phase undervoltage signal is output. Wherein, the undervoltage reference signal can be generated by dividing the voltage of the DC power supply unit 10 by using a voltage dividing resistor.

The undervoltage delay unit 70 includes a first phase undervoltage delay subunit 701 , a second phase undervoltage delay subunit 702 and a third phase undervoltage delay subunit 703 . Wherein, the first phase undervoltage delay subunit 701 is used to delay the output of the first phase undervoltage judgment subunit 601 for a second set time, and in the first phase undervoltage judgment subunit 601 When the high level output time reaches the second set time, control the undervoltage delay trigger unit 802 with an operational amplifier to trigger the circuit breaker to disconnect; the second phase undervoltage delay subunit 702 is used to control the first phase The output of the two-phase undervoltage judgment subunit 602 is delayed for a second set time, and when the time when the second phase undervoltage judgment subunit 602 outputs a high level reaches the second set time, the control The undervoltage delay trigger unit 802 with an operational amplifier triggers the disconnection of the circuit breaker; the third phase undervoltage delay subunit 703 is used to determine the output of the third phase undervoltage judgment subunit 603 for the second set time Delayed output, when the time when the third phase undervoltage judging subunit 603 outputs a high level reaches the second set time, output a high level indicating a trigger signal to control the undervoltage delay with an operational amplifier The timing trigger unit 802 triggers the coil of the circuit breaker in the three-phase power system circuit to be turned on, so that the circuit breaker is disconnected.

It can be seen from the application shown in FIG. 2 that three operational amplifiers, namely the first operational amplifier to the third operational amplifier, are used in the overvoltage judging unit 40, and three operational amplifiers are used in the undervoltage judging unit 60. That is, the fourth operational amplifier to the sixth operational amplifier, and two operational amplifiers are used in the circuit breaker trigger unit 80, a total of eight operational amplifiers are used, and the cost of adopting so many operational amplifiers is relatively high, so that The cost of the overvoltage and undervoltage protection system in this application is relatively high.

Based on the overvoltage and undervoltage protection system of the three-phase power supply system shown in Figure 2, the utility model can reduce the cost of the overvoltage and undervoltage protection system by reducing the number of operational amplifiers in the overvoltage and undervoltage system.

Fig. 3 shows a schematic structural view of an embodiment of the present invention. As shown in FIG. 3 , in the embodiment of the present invention, the number of operational amplifiers in the overvoltage judging unit 40 can be reduced first. Specifically, it may include: adding a first signal isolation and OR unit 90 between the sampling unit 30 and the overvoltage judging unit 40, which is used to isolate the sampling voltage signal corresponding to each phase voltage output obtained by the sampling unit 30, and Output the sampled voltage signal with the highest voltage value.

Correspondingly, the overvoltage judging unit 40 may only include an overvoltage judging subunit 404, and the overvoltage judging subunit 404 may include an operational amplifier, which is powered by the DC power supply unit 10 and is used to convert the The sampling voltage signal output by the first signal isolation, OR unit 90 is compared with the overvoltage reference signal provided by the system, and the sampling voltage signal output by the first signal isolation, OR unit 90 is higher than the overvoltage reference signal When, the output represents the high level of the overvoltage signal. Wherein, the overvoltage reference signal can be generated by dividing the voltage of the DC power supply unit 10 by using a voltage dividing resistor. During specific implementation, other circuits capable of realizing the above-mentioned comparison and judgment function may also be used to replace the operational amplifier in the above-mentioned overvoltage judging subunit 404 .

Correspondingly, the overvoltage delay unit 50 also only includes a delay subunit 504, which is used to delay the output of the output of the overvoltage judgment subunit 404 for a first set time, and in the overvoltage judgment subunit 404 outputs a high level indicating a trigger signal to the circuit breaker trigger unit 80 when the time for outputting the high level reaches the first set time.

Now, except above-mentioned first signal isolation, fetching or unit 90, overvoltage judging unit 40 and overvoltage delay unit 50, the function and connection relation of each other constituent units can be with the function and the connection relationship of each constituent unit shown in Fig. 1 The connections are the same.

In addition, in another embodiment of the present invention, on the basis of the system shown in FIG. 3 , the op amps in the overvoltage delay trigger unit 801 with op amps and the undervoltage delay trigger unit 802 with op amps can be further reduced. As shown in Figure 4, it may specifically include: adding a second signal isolation, OR unit 100 between the overvoltage delay unit 50, the undervoltage delay unit 70, and the circuit breaker trigger unit 80, for controlling the undervoltage delay unit 70 and the output of the overvoltage delay unit 50 are respectively isolated and concentrated to one point, and when any one of the outputs is at a high level, it outputs a high level to the circuit breaker trigger unit 80 . When the circuit breaker triggering unit 80 receives the high level indicating the trigger signal, it triggers the conduction of the circuit breaker coil in the three-phase power system loop, so that the circuit breaker is disconnected.

At this time, the circuit breaker trigger unit 80 can be a delay trigger unit with an operational amplifier shared by overvoltage and undervoltage, or a circuit breaker trigger unit without an operational amplifier at all, that is, as shown in FIG. 3 The Zener transistor turns on the trigger unit 803 .

Further, in other embodiments of the present invention, the number of operational amplifiers in the undervoltage judging unit 60 can also be reduced on the basis of the system shown in FIG. 4 . As shown in Figure 5, at this time, the undervoltage judging unit 60 may only include one undervoltage judging subunit 604, and the undervoltage judging subunit 604 includes an operational amplifier, which is powered by the DC power supply unit 10 , for comparing the sampling voltage signal output by the first signal isolation, OR unit 90 with the undervoltage reference signal provided by the system, where the sampling voltage signal output by the first signal isolation, OR unit 90 is lower than When the undervoltage reference signal is used, the output indicates a high level of the undervoltage signal. Wherein, the undervoltage reference signal can be generated by dividing the voltage of the DC power supply unit 10 by using a voltage dividing resistor. During specific implementation, other circuits capable of realizing the above-mentioned comparison and judgment function may also be used to replace the operational amplifier in the under-voltage judging subunit 604 .

Correspondingly, the undervoltage delay unit 70 only includes one undervoltage delay subunit 704 corresponding to the undervoltage judgment subunit 604, which is used to perform a second set time on the output of the undervoltage judgment subunit 604 When the delay output of the undervoltage judging subunit 604 reaches the first set time, the high level of the trigger signal is output to the circuit breaker trigger unit 80 .

In specific implementation, each component unit and subunit in the overvoltage and undervoltage protection system of the above-mentioned three-phase power supply system has various specific implementation forms.

Taking the over-voltage delay sub-unit and the under-voltage delay sub-unit as examples, both of them can be realized by an ordinary RC delay circuit, or by an RC delay control circuit with a MOS transistor.

FIG. 6 shows a schematic structural diagram of a delay subunit of an RC delay control circuit with a MOS transistor. In FIG. 6 , the overvoltage delay subunit 504 is taken as an example. As shown in FIG. 6 , the delay subunit 504 includes: a first RC delay circuit 5041 , a normally closed controllable switch K and a MOS transistor Q5 . Wherein, the input terminal of the first RC delay circuit 5041 is connected to the output terminal of the overvoltage judging subunit 404, and the output terminal of the first RC delay circuit 5041 is connected to the control terminal of the normally closed controllable switch K, so One connection terminal of the controllable switch K is connected to the DC power supply, and the other connection terminal is grounded; the control terminal of the MOS transistor Q5, that is, the gate is connected to the output terminal of the overvoltage judging subunit 404, and the drain is connected to the DC power supply. , source to ground. The first RC delay circuit 5041 is used to delay the output of the overvoltage judging subunit 404. When the predetermined delay time is reached, the normally closed controllable switch K is turned off, and the DC power is connected to the MOS tube Drain of Q5.

In actual implementation, the first RC delay circuit 5041 can be implemented by two-stage RC delay sub-circuits with triodes and a regulator tube, and the normally closed orifice switch K can be implemented by two linkage-controlled triodes. In addition, there may be other specific implementation manners, which will not be listed one by one here.

An example is given below to describe a specific implementation thereof. FIG. 7 is a schematic structural diagram corresponding to an overvoltage and undervoltage protection system of a three-phase power system in an example of the embodiment shown in FIG. 4 . As shown in Fig. 6, a circuit breaker Sw is connected in series in the loop of the three-phase power supply system Ua, Ub, Uc, N.

In this example, the rectification unit 20 adopts half-wave rectification, that is, diode D1 (ie, the first phase rectifier subunit), diode D2 (ie, the second phase rectifier subunit) and diode D3 (ie, the third phase rectifier subunit) are used respectively. Unit) performs half-wave rectification on the Ua phase voltage output, Ub phase voltage output and Uc phase voltage output of the three-phase power system.

The DC power supply unit 10 includes: a diode D4, voltage limiting resistors R1, R2, R3, R4 and R5 connected in series, a charging and discharging capacitor C4, a voltage regulator D40, a voltage limiting resistor R38 and a voltage regulator D41. Wherein, the anode of the diode D4 is connected to the one-phase output terminal of the rectifier unit, in this example, it is connected to the cathode of the diode D1; the cathode of the diode D4 is connected to the voltage limiting resistor R1; the voltage limiting resistor R5 is connected to one end of the charging and discharging capacitor C4; The other end of the charging and discharging capacitor C4 is grounded; the regulator tube D40 is connected in parallel with the charging and discharging capacitor C4; the voltage limiting resistor R38 is connected in series with the regulator tube D41 and then connected in parallel with the regulator tube D40. Wherein, the voltage-limiting resistor R38 is connected to the positive pole of the voltage stabilizing transistor D41, and the negative pole of the voltage stabilizing transistor D41 is grounded. The anode of the regulator tube D41 is the output end of the DC power supply unit 10 . During specific implementation, the voltage limiting resistors R1, R2, R3, R4 and R5 may also be replaced by one resistor or other numbers of resistors.

The sampling unit 30 includes three sampling subunits. In this example, the first phase sampling subunit 301 is used to collect the voltage output of the Ua phase and output a corresponding sampling voltage signal. It specifically includes: voltage dividing resistors R6, R7 and R8 connected in series, voltage dividing resistor R15, diode D5, charging and discharging capacitor C1 and charging and discharging resistor R18. Wherein, the voltage dividing resistor R6 is connected to one phase output of the rectifier unit 20, and in this example is connected to the cathode of the diode D1; the voltage dividing resistor R8 is connected to one end of the voltage dividing resistor R15 and the anode of the diode D5; the other end of the voltage dividing resistor R15 One end is grounded; the negative pole of the diode D5 is connected to one end of the charge and discharge capacitor C1; the other end of the charge and discharge capacitor C1 is grounded; the charge and discharge resistor R18 is connected in parallel with the charge and discharge capacitor C1; the non-ground end of the charge and discharge resistor R18 is the first phase The output of subunit 301 is used. The second phase sampling subunit 302 is used to collect the voltage output of the Ub phase and output a corresponding sampled voltage signal. It specifically includes: voltage dividing resistors R9, R10 and R11 connected in series, voltage dividing resistor R16, diode D6, charging and discharging capacitor C2 and charging and discharging resistor R19. Wherein, the voltage dividing resistor R9 is connected to one phase output of the rectifier unit 20, and in this example is connected to the cathode of the diode D2; the voltage dividing resistor R11 is connected to one end of the voltage dividing resistor R16 and the anode of the diode D6; the other end of the voltage dividing resistor R16 One end is grounded; the negative pole of the diode D6 is connected to one end of the charge and discharge capacitor C2; the other end of the charge and discharge capacitor C2 is grounded; the charge and discharge resistor R19 is connected in parallel with the charge and discharge capacitor C2; the non-ground end of the charge and discharge resistor R19 is the second phase The output of subunit 302 is used. The third phase sampling subunit 303 is used to collect the voltage output of the Uc phase and output a corresponding sampled voltage signal. It specifically includes: voltage dividing resistors R12, R13 and R14 connected in series, voltage dividing resistor R17, diode D7, charging and discharging capacitor C3 and charging and discharging resistor R20. Wherein, the voltage dividing resistor R12 is connected with one phase output of the rectifying unit 20, and in this example is connected with the cathode of the diode D3; the voltage dividing resistor R14 is connected with one end of the voltage dividing resistor R17 and the anode of the diode D7; the other end of the voltage dividing resistor R17 One end is grounded; the negative pole of the diode D7 is connected to one end of the charge and discharge capacitor C3; the other end of the charge and discharge capacitor C3 is grounded; the charge and discharge resistor R20 is connected in parallel with the charge and discharge capacitor C3; the non-ground end of the charge and discharge resistor R20 is the third phase The output of subunit 303 is used.

In the utility model, by using multiple sub-resistors in the DC voltage unit and the adopting unit to form a voltage dividing resistor, the limited narrow space can be fully utilized, the power consumption of the system can be reduced, and a better heat dissipation area can be realized.

The undervoltage reference signal is obtained by dividing the output of the DC voltage unit 10 by the voltage dividing resistor R21 and the voltage dividing resistor R22, that is, the voltage dividing resistor R21 and the voltage dividing resistor R22 connected in series, one end of which is connected to the output end of the DC voltage unit 10 connected, and the other end is grounded. The connection point between the voltage dividing resistor R21 and the voltage dividing resistor R22 is an undervoltage reference signal. That is, the non-ground terminal of the voltage dividing resistor R22 is the undervoltage reference signal.

The undervoltage judging unit 60 includes three undervoltage judging subunits, the first undervoltage judging subunit 601 includes an operational amplifier U1A, and the operational amplifier U1A is powered by the DC voltage unit 10, that is, the power supply terminal of the operational amplifier U1A and the regulator tube The positive pole of D41 is connected, the negative power terminal of the operational amplifier U1A is grounded, and the operational amplifier U1A is used to judge the undervoltage of the sampling voltage signal of the Ua phase by using the undervoltage reference signal. Specifically, the inverting input terminal of the operational amplifier U1A receives the sampling voltage signal of the Ua phase, and the forward input terminal receives the undervoltage reference signal, that is, the inverting input terminal is connected to the non-ground terminal of the charging and discharging resistor R18, and the forward input terminal is connected to the non-ground terminal of the charging and discharging resistor R18. The non-ground terminals of the voltage dividing resistor R22 are connected. The second undervoltage judging subunit 602 includes an operational amplifier U1B, which is powered by the DC voltage unit 10, that is, the power supply terminal of the operational amplifier U1B is connected to the positive pole of the regulator tube D41, and the negative power supply terminal of the operational amplifier U1B is grounded. The operational amplifier U1B is used to judge the undervoltage of the sampled voltage signal of the Ub phase by using the undervoltage reference signal. Specifically, the inverting input terminal of the operational amplifier U1B receives the sampling voltage signal of the Ub phase, and the forward input terminal receives the undervoltage reference signal, that is, the inverting input terminal is connected to the non-ground terminal of the charging and discharging resistor R19, and the forward input terminal is connected to the non-ground terminal of the charging and discharging resistor R19. The non-ground terminals of the voltage dividing resistor R22 are connected. The third undervoltage judging subunit 603 includes an operational amplifier U1C, which is powered by the DC voltage unit 10, that is, the power supply end of the operational amplifier U1C is connected to the positive pole of the regulator tube D41, and the negative power supply terminal of the operational amplifier U1C is grounded. The operational amplifier U1C is used for judging the undervoltage of the sampled voltage signal of the Uc phase by using the undervoltage reference signal. Specifically, the inverting input terminal of the operational amplifier U1C receives the sampling voltage signal of the Uc phase, and the forward input terminal receives the undervoltage reference signal, that is, the inverting input terminal is connected to the non-ground terminal of the charging and discharging resistor R20, and the forward input terminal is connected to the non-ground terminal of the charging and discharging resistor R20. The non-ground terminals of the voltage dividing resistor R22 are connected.

The undervoltage delay unit 70 includes three undervoltage delay subunits, and the first phase undervoltage delay subunit 701 includes: a diode D11, a voltage limiting resistor R23, a charging and discharging capacitor C5, and a charging and discharging resistor R27. Wherein, the anode of the diode D11 is connected to the output end of the corresponding operational amplifier. In this example, the anode of the diode D11 is connected to the output end of the operational amplifier U1A; the cathode of the diode D11 is connected to one end of the voltage limiting resistor R23; the voltage limiting resistor R23 The other end of the charging and discharging capacitor C5 is connected to one end; the other end of the charging and discharging capacitor C5 is grounded, and the charging and discharging resistor R27 is connected in parallel with the charging and discharging capacitor C5; the non-grounded end of the charging and discharging resistor R27 is the first phase undervoltage delay timer The output of unit 701. The first phase undervoltage delay subunit 702 includes: a diode D12, a voltage limiting resistor R24, a charging and discharging capacitor C5, and a charging and discharging resistor R28. Wherein, the anode of the diode D12 is connected to the output end of the corresponding operational amplifier. In this example, the anode of the diode D12 is connected to the output end of the operational amplifier U1B; the cathode of the diode D12 is connected to one end of the voltage limiting resistor R24; the voltage limiting resistor R24 The other end of the charging and discharging capacitor C6 is connected to one end; the other end of the charging and discharging capacitor C6 is grounded, and the charging and discharging resistor R28 is connected in parallel with the charging and discharging capacitor C6; the non-grounded end of the charging and discharging resistor R28 is the second phase undervoltage delay timer The output of unit 702. The third phase undervoltage delay subunit 703 includes: a diode D13, a voltage limiting resistor R25, a charging and discharging capacitor C7, and a charging and discharging resistor R29. Wherein, the anode of the diode D13 is connected to the output end of the corresponding operational amplifier. In this example, the anode of the diode D13 is connected to the output end of the operational amplifier U1C; the cathode of the diode D13 is connected to one end of the voltage limiting resistor R25; the voltage limiting resistor R25 The other end of the charging and discharging capacitor C7 is connected to one end; the other end of the charging and discharging capacitor C7 is grounded, and the charging and discharging resistor R29 is connected in parallel with the charging and discharging capacitor C7; the non-grounded end of the charging and discharging resistor R29 is the third phase undervoltage delay timer The output of unit 703.

The first signal isolation, or unit 90 includes: a pull-down resistor R26 and three diodes D8, D9 and D10, wherein the anode of the diode D8 is connected to the output of the first phase sampling subunit 301, that is, the non-ground terminal of R18; The positive pole of D9 is connected with the output of the second phase sampling subunit 302, that is, the non-ground terminal of R19; the positive pole of the diode D10 is connected with the output of the third phase sampling subunit 303, that is, the non-ground terminal of R20; and diodes D8, D9 After being connected with the negative pole of D10, it is used as the output of the first signal isolation and OR unit 90; one end of the pull-down resistor R26 is connected with the negative poles of the three diodes D8, D9 and D10, and the other end of the pull-down resistor R26 is grounded .

The overvoltage reference signal is obtained by dividing the output of the DC voltage unit 10 by the voltage dividing resistor R30 and the voltage dividing resistor R31, that is, the voltage dividing resistor R30 and the voltage dividing resistor R31 connected in series, one end of which is connected to the output terminal of the DC voltage unit 10 connected, and the other end is grounded. The connection point between the voltage dividing resistor R30 and the voltage dividing resistor R31 is the overvoltage reference signal, that is, the non-ground terminal of the voltage dividing resistor R31 is the overvoltage reference signal.

The overvoltage judging unit 40 only includes an overvoltage judging subunit 404. The overvoltage judging subunit 404 is composed of an operational amplifier U1D, which is powered by the DC voltage unit 10, that is, the power supply terminal of the operational amplifier U1D is connected to the voltage regulator The anode of the tube D41 is connected, and the negative power supply terminal of the operational amplifier U1D is grounded. The operational amplifier U1D is used to judge the overvoltage of the sampling voltage signal output by the first signal isolation and OR unit 90 by using the overvoltage reference signal. Specifically, the forward input terminal of the operational amplifier U1D receives the sampling voltage signal output by the first signal isolation and OR unit 90, and the negative input terminal receives the overvoltage reference signal, that is, the forward input terminal is connected to the three diodes D8, D9 and The negative pole of D10 is connected, and the reverse input terminal is connected with the non-ground terminal of the voltage dividing resistor R31.

The overvoltage delay unit 50 includes only one overvoltage delay subunit 504, and the overvoltage delay subunit 504 includes: a triode Q1, a charging and discharging capacitor C8, a voltage limiting resistor R33, a triode Q2, a voltage limiting resistor R35, a charging and discharging capacitor C9, Charge and discharge resistor R34, diode D17, regulator tube D42, triode Q3, voltage limiting resistor R37, triode Q4, voltage limiting resistor R36 and MOS tube Q5. Wherein, the base of the transistor Q1 is connected to the output terminal of the corresponding operational amplifier. In this example, it is connected to the output terminal of the operational amplifier U1D, and the collector of the transistor Q1 is connected to the output terminal of the DC power supply unit 10, that is, the voltage regulator The positive pole of D41 is connected; the emitter of the triode Q1 is connected with one end of the charging and discharging capacitor C8; the other end of the charging and discharging capacitor C8 is grounded; one end of the three-voltage limiting resistor R33 is connected with the emitter of the triode Q1, and the other end is connected with the base of the triode Q2 The collector of the transistor Q2 is connected to one end of the voltage limiting resistor R35, and the emitter is connected to one end of the charging and discharging capacitor C9; the other end of the voltage limiting resistor R35 is connected to the output end of the DC power supply unit 10, that is, to the stable The positive pole of the pressure tube D41 is connected; the other end of the charging and discharging capacitor C9 is grounded; the charging and discharging resistor R34 is connected in parallel with the charging and discharging capacitor C9; the positive pole of the diode D17 is connected to the non-grounded end of the charging and discharging resistor R34, and the negative pole is connected to the regulator tube D42 The anode of the voltage regulator tube D42 is connected to the base of the transistor Q3; the emitter of the transistor Q3 is grounded, the collector is connected to the base of the transistor Q4 and one end of the voltage limiting resistor R37; The other end of the voltage limiting resistor R37 is connected to the output end of the DC power supply unit 10, that is, connected to the positive pole of the voltage regulator tube D41; the emitter of the transistor Q4 is grounded, and the collector is connected to one end of the voltage limiting resistor R36; The other end of the piezoresistor R36 is connected to the output end of the DC power supply unit 10, that is, to the anode of the regulator tube D41; the gate of the MOS transistor Q5 is connected to the output end of the overvoltage judging sub-unit 404, that is, the output end of the operational amplifier U1D The output end is connected, the drain is connected to the collector of the transistor Q4 , and the source is the output end of the overvoltage delay sub-unit 504 .

The second signal isolation, OR unit 100 includes a pull-down resistor R32 and a plurality of diodes consistent with the output of the undervoltage delay unit 70 and the overvoltage delay unit 50. In this example, the undervoltage delay unit 70 There are three outputs and one output of the overvoltage delay unit 50, so there are four diodes in the second signal isolation and OR unit 100, namely diodes D14, D15, D16 and D18. Wherein, the anode of the diode D14 is connected to the output of the first phase undervoltage delay subunit 701, that is, connected to the non-ground terminal of R27; the anode of the diode D15 is connected to the output of the second phase undervoltage delay subunit 702, that is, to the R25 The non-ground terminal of the diode D16 is connected with the output of the third-phase undervoltage delay subunit 703, that is, connected with the non-ground terminal of R29; the positive pole of the diode D18 is connected with the output of the overvoltage delay subunit 504, that is, with The source of the MOS tube is connected; and the negative poles of the diodes D14, D15, D16 and D18 are connected together as the output of the second signal isolation, or unit 100; one end of the pull-down resistor R32 is connected to the four diodes D14, The negative poles of D15, D16 and D18 are connected, and the other end of the pull-down resistor R32 is grounded.

The circuit breaker trigger unit 80 in this example is a voltage regulator conduction trigger unit 804, which includes: a voltage regulator transistor D43, a thyristor U1 and a first capacitor C10. Wherein, the anode of the regulator tube D43 is connected to the output end of the second signal isolation, OR unit 100, that is, connected to the cathodes of the four diodes D14, D15, D16 and D18; the cathode of the regulator tube D43 is connected to the The gate of the thyristor U1 is connected, one main terminal of the thyristor U1 is connected to the circuit breaker coil Coil in the three-phase power system circuit, and the other main terminal is grounded, and one end of the capacitor C10 is connected to the voltage regulator The negative pole of the tube D43 is connected, and the other end is grounded.

In other examples of the present utility model, the undervoltage delay subunit 701, 702 and 703 can adopt the internal structure of the overvoltage delay subunit 504 shown in FIG. 7; The internal structures of the undervoltage delay subunits 701, 702 and 703 are shown. Moreover, the first phase undervoltage subunit 701 , the second phase undervoltage subunit 702 and the third phase undervoltage subunit 703 may have the same internal structure, or may have different internal structures.

In addition, this utility model also provides another optional internal structure implementation of the undervoltage delay subunit 701, 702, 703 and overvoltage delay subunit 504, as shown in Figure 8, in Figure 8, the overvoltage delay subunit Taking the time sub-unit as an example, it may include: a diode D19, a voltage limiting resistor R39, a charging and discharging capacitor C11, a charging and discharging resistor R40, a voltage regulator tube D44 and a MOS tube Q6. Wherein, the anode of the diode D19 is connected to the output terminal of the corresponding operational amplifier U1D, the cathode of the diode D19 is connected to one end of the voltage limiting resistor R39; the other end of the voltage limiting resistor R39 is connected to one end of the charging and discharging capacitor C11; the charging and discharging The other end of the capacitor C11 is grounded; the charge and discharge resistor R40 is connected in parallel with the charge and discharge capacitor C11; the positive pole of the voltage regulator tube D44 is connected to the non-ground end of the charge and discharge resistor R40, and the negative pole of the voltage regulator tube D44 is connected to the gate of the MOS transistor Q6; The drain of the MOS transistor Q6 is connected to the anode of the diode D19 , and the source is the output terminal of the overvoltage delay sub-unit 504 .

In addition, the undervoltage delay subunit 704 may also have an internal structure of any of the above-mentioned specific implementation forms.

In the utility model, by using a delay circuit with a MOS tube in the undervoltage delay unit and the overvoltage delay unit, the AND logic of the delay output and the output of the operational amplifier can be realized, thereby avoiding the occurrence of misoperation.

The above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present utility model shall be included in the Within the protection scope of the present utility model.

Claims (11)

1. An overvoltage and undervoltage protection system for a three-phase power supply system, the overvoltage and undervoltage protection system can generate an undervoltage reference signal and an overvoltage reference signal; it is characterized in that it includes a rectification unit (20) , sampling unit (30), undervoltage judgment unit (60), undervoltage delay unit (70), first signal isolation, OR unit (90), overvoltage judgment unit (40), overvoltage delay unit (50) and a circuit breaker trigger unit (80), wherein: The rectification unit (20) is used to convert the voltage output of each phase of the three-phase power system from AC to DC for output; The sampling unit (30) is used to sample each phase voltage output of the three-phase power system rectified by the rectification unit (20), and output a sampling voltage signal corresponding to each phase voltage output; The undervoltage judging unit (60) is used to compare the currently input one-phase sampling voltage signal with the undervoltage reference signal, and output an undervoltage signal when the currently input sampling voltage signal is lower than the undervoltage reference signal. Pressure signal; The undervoltage delay unit (70) is used to output a trigger signal to the circuit breaker trigger unit (80) when the time for the undervoltage judging unit (60) to output the undervoltage signal reaches a second set time; The first signal isolation and OR unit (90) is used to isolate the sampling voltage signal corresponding to each phase voltage output obtained by the sampling unit (30), and output the sampling voltage signal with the highest voltage value among them; The overvoltage judging unit (40) is used to compare the sampling voltage signal output by the first signal isolation and OR unit (90) with the overvoltage reference signal, and when the first signal isolation, OR When the sampling voltage signal output by the unit (90) is higher than the overvoltage reference signal, an overvoltage signal is output; The overvoltage delay unit (50) is used to output a trigger signal to the circuit breaker trigger unit (80) when the time for the overvoltage judging unit (40) to output the overvoltage signal reaches a first set time; The circuit breaker trigger unit (80) is used to trigger the disconnection in the three-phase power system loop when receiving the trigger signal output by the undervoltage delay unit (70) or the overvoltage delay unit (50) The coil of the circuit breaker is turned on and the circuit breaker is opened. 2. The system according to claim 1, characterized in that, said first signal isolation, OR unit (90) comprises: a first pull-down resistor (R26) and three first diodes (D8, D9 , D10), the anode of each first diode (D8, D9, D10) is connected to the one-phase output terminal of the sampling unit (30), and the cathodes are connected together as the first signal, isolated OR unit ( 90) output; one end of the first pull-down resistor (R26) is connected to the cathodes of the three first diodes (D8, D9, D10), and the other end is grounded. 3. The system according to claim 1, characterized in that, the system further comprises: a second signal isolation, OR unit (100), used for the under-voltage delay unit (70) and the over-delay The outputs of the time unit (50) are respectively isolated and concentrated to one point, and when any one of the outputs is a trigger signal, the trigger signal is output to the circuit breaker trigger unit (80); The circuit breaker trigger unit (80) includes: a first voltage regulator transistor (D43), a thyristor (U1) and a first capacitor (C10); the anode of the first voltage regulator transistor (D43) is connected to the second Two signal isolation, the output terminal of the OR unit (100) is connected, the negative pole is connected with the gate of the silicon controlled rectifier (UI), and one main terminal of the silicon controlled rectifier (UI) is connected with the three-phase power system loop The circuit breaker coil is connected, the other main terminal is grounded, one end of the first capacitor (C10) is connected to the negative pole of the first voltage regulator tube (D43), and the other end is grounded. 4. The system according to claim 3, characterized in that, the second signal isolation, OR unit (100) comprises: a second pull-down resistor (R32) and the undervoltage delay unit (70) and the A plurality of second diodes (D14, D15, D16, D18) consistent with the output quantity of the overvoltage delay unit (50), the anode of each second diode (D14, D15, D16, D18) and its The output terminals of the corresponding undervoltage delay unit (70) or overvoltage delay unit (50) are connected, and the negative poles are connected together as the output terminal of the second signal isolation, OR unit (100) and the circuit breaker trigger unit ( 80) connected to the input; one end of the second pull-down resistor (R32) is connected to the cathodes of the plurality of second diodes (D14, D15, D16, D18), and the other end is grounded. 5. The system according to claim 1, characterized in that the undervoltage judging unit (60) comprises: three undervoltage judging subunits (601, 602, 603), each undervoltage judging subunit (601 , 602, 603) are respectively used to compare the one-phase sampling voltage signal output by the sampling unit (60) with the undervoltage reference signal, and when the phase sampling voltage signal is lower than the undervoltage reference signal, output the corresponding Phase undervoltage signal; The undervoltage delay unit (70) includes: three undervoltage delay subunits (701, 702, 703), each undervoltage delay subunit (701, 702, 703) corresponds to an undervoltage judgment subunit (601, 602, 603) output. 6. The system according to claim 1, characterized in that the undervoltage judging unit (60) comprises: an undervoltage judging subunit (604) for isolating the first signal, taking an OR unit ( 90) compare the output sampling voltage signal with the undervoltage reference signal, and output the undervoltage signal when the sampling voltage signal output by the first signal isolation and OR unit (90) is lower than the undervoltage reference signal ; The undervoltage delay unit (70) includes: an undervoltage delay subunit (704) corresponding to the undervoltage judgment subunit (604). 7. The system according to any one of claims 1 to 6, characterized in that, the overvoltage delay unit (50) is an RC delay circuit, or an RC delay control circuit with a MOS tube; The undervoltage delay unit (70) is an RC delay circuit, or an RC delay control circuit with a MOS tube. 8. The system according to claim 7, wherein the RC delay control circuit with a MOS tube comprises: The fourth diode (D19), the second voltage limiting resistor (R39), the second charging and discharging capacitor (C11), the second charging and discharging resistor (R40), the second voltage regulator tube (D44) and the first MOS tube ( Q6); the anode of the fourth diode (D19) is connected to the output terminal of the corresponding overvoltage judgment unit (40) or undervoltage judgment unit (60), and the cathode is connected to the second voltage limiting resistor (R39) The other end of the second voltage limiting resistor (R39) is connected to one end of the second charging and discharging capacitor (C11); the other end of the second charging and discharging capacitor (C11) is grounded, and the first Two charging and discharging resistors (R40) are connected in parallel with the second charging and discharging capacitor (C11); Connected to the gate of the first MOS transistor (Q6); the drain of the first MOS transistor (Q6) is connected to the anode of the fourth diode (D19), and the source is the overvoltage delay unit (50) or the output terminal of undervoltage delay unit (70); Alternatively, the RC delay control circuit with a MOS tube includes: a first RC delay circuit (5041), a controllable switch (K) and a second MOS tube (Q5); The input end of the first RC delay circuit (5041) is connected to the output end of the corresponding overvoltage judgment unit (40) or undervoltage judgment unit (60), and the output of the first RC delay circuit (5041) terminal is connected to the control terminal of the controllable switch (K), one connection terminal of the controllable switch (K) is connected to the DC power supply, and the other connection terminal is grounded; the control terminal of the MOS transistor (Q5) is connected to the The output terminal of the voltage judging unit (60) or the overvoltage judging unit (40) is connected, the drain is connected with the DC power supply, and the source is the output terminal of the overvoltage delay unit (50) or the undervoltage delay unit (70). 9. The system according to claim 8, characterized in that the first RC delay circuit (5041) comprises: a first triode (Q1), a third charging and discharging capacitor (C8), a third voltage limiting Resistor (R33), second triode (Q2), fourth voltage limiting resistor (R35), fourth charge and discharge capacitor (C9), third charge and discharge resistor (R34), fifth diode (D17) and The second regulator tube (D42); the base of the first triode (Q1) is connected to the output terminal of the corresponding overvoltage judgment unit (40) or undervoltage judgment unit (60), and the collector is connected to the DC power supply The emitter is connected to one end of the third charging and discharging capacitor (C8); the other end of the third charging and discharging capacitor (C8) is grounded; one end of the third voltage limiting resistor (R33) is connected to the first three The emitter of the transistor (Q1) is connected, and the other end is connected with the base of the second transistor (Q2); the collector of the second transistor (Q2) is connected with one end of the fourth voltage limiting resistor (R35) The emitter is connected to one end of the fourth charging and discharging capacitor (C9); the other end of the fourth voltage limiting resistor (R35) is connected to a DC power supply; the other end of the fourth charging and discharging capacitor (C9) is grounded; The third charging and discharging resistor (R34) is connected in parallel with the fourth charging and discharging capacitor (C9); the anode of the fifth diode (D17) is connected to the non-ground terminal of the third charging and discharging resistor (R34) The negative pole is connected to the positive pole of the second voltage stabilizing tube (D42); the negative pole of the second voltage stabilizing tube (D42) is the output end of the first RC delay circuit (5041). 10. The system according to claim 9, characterized in that the controllable switch (K) comprises: a third triode (Q3), a fifth voltage limiting resistor (R37), a fourth triode (Q4 ) and the sixth voltage limiting resistor (R36); the base of the third transistor (Q3) is connected to the output terminal of the first RC delay circuit (5041); the third transistor (Q3 )’s emitter is grounded, the collector is connected to the base of the fourth triode (Q4) and one end of the fifth voltage limiting resistor (R37); the other end of the fifth voltage limiting resistor (R37) is connected to the DC power supply ; The emitter of the fourth triode (Q4) is grounded, and the collector is connected to one end of the sixth voltage limiting resistor (R36); the other end of the sixth voltage limiting resistor (R36) is connected to a DC power supply . 11. The system according to any one of claims 8 to 10, wherein the DC power supply is generated by dividing and stabilizing the voltage output of a certain phase of a three-phase power supply system.

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