Voltage detection circuit for electric energy quality monitoring

Abstract

The utility model discloses a voltage detection circuit for electric energy quality monitoring, which relates to the technical field of electric energy quality monitoring, and comprises a voltage detection module used for carrying out voltage sampling and signal processing on a power grid; the alternating current abrupt change detection module is used for judging whether the signal output by the voltage detection module is abrupt or not; the power module is used for supplying power; the isolation detection module is used for isolated transmission of signals; the timing control module is used for regularly controlling the signal transmission work of the signal transmission module; the signal transmission module is used for transmitting a signal output by the voltage detection module to the electric energy quality detection module when the voltage detection module changes suddenly or is within a set time; and the electric energy quality monitoring module is used for clamping, filtering and data analysis. The voltage detection circuit for electric energy quality monitoring reduces the data processing amount, meets the voltage detection requirement, reduces the workload of an electric energy quality monitoring module, and improves the working efficiency of the electric energy quality monitoring module.

Description

Technical Field

[0001] The utility model relates to the technical field of power quality monitoring, in particular to a voltage detection circuit for power quality monitoring. Background Art

[0002] With the development of society, power quality problems have attracted more and more attention from society. In order to ensure the safe operation of the power grid, it is necessary to strengthen the management of power quality and establish a perfect power quality monitoring system. The voltage detection circuit for power quality monitoring in the prior art generally consists of a signal processing circuit composed of a voltage transformer and an operational amplifier to realize voltage sampling and signal amplification and filtering processing of the power grid. Then, the power quality monitoring device receives and analyzes the data. It is necessary to sample the power grid voltage in real time, resulting in the power quality monitoring device needing to receive, store, and analyze data in real time. A large amount of data processing and storage are likely to reduce the working efficiency and service life of the power quality monitoring device. Therefore, it needs to be improved. Summary of the Utility Model

[0003] An embodiment of the utility model provides a voltage detection circuit for power quality monitoring to solve the problems proposed in the above background art.

[0004] To achieve the above object, the utility model provides the following technical solutions:

[0005] A voltage detection circuit for power quality monitoring includes: a voltage detection module, an AC mutation detection module, a power supply module, an isolation detection module, a timing control module, a signal transmission module, and a power quality monitoring module;

[0006] The voltage detection module is used to sample the voltage of the power grid, isolate and transmit the sampled signal, amplify and filter the signal, and output a first detection signal;

[0007] The AC mutation detection module is connected to the voltage detection module and is used to perform phase shift processing on the first detection signal and output a phase-shifted signal, and is used to superimpose the phase-shifted signal and the first detection signal and output a second detection signal when a voltage mutation occurs in the first detection signal;

[0008] The power supply module is used to provide DC power;

[0009] The isolation detection module is connected to the power supply module and the AC mutation detection module and is used to receive DC power and the second detection signal, and output a first control signal when the second detection signal is a positive voltage, and output a second control signal when the second detection signal is a negative voltage;

[0010] A timing control module, connected to the power supply module, is used to set a timing time, and when receiving DC electric energy, output a third control signal at a fixed time, and stop outputting the third control signal after the timing ends;

[0011] A signal transmission module, connected to the isolation detection module, timing control module, voltage detection module and power quality monitoring module, is used to receive the first control signal, the second control signal or the third control signal and transmit the received first detection signal to the power quality detection module;

[0012] A power quality monitoring module is used to perform clamping and filtering processing on the first control signal, the second control signal or the third control signal transmitted by the signal transmission module, and transmit the processed signal to the power quality monitoring device.

[0013] As a further solution of the present invention: The voltage detection module includes a detection interface, a first varistor, a first transformer, a first resistor, a first operational amplifier, a second resistor, a third resistor and a fourth resistor;

[0014] Preferably, the first end of the detection interface is connected to the first input end of the first transformer through the first varistor, the second end of the detection interface is connected to the second input end of the first transformer, the first output end of the first transformer is connected to the non-inverting end of the first operational amplifier through the first resistor and grounded through the third resistor, the inverting end of the first operational amplifier is connected to one end of the fourth resistor and connected to the second output end of the first transformer and the ground end through the second resistor, and the output end of the first operational amplifier is connected to the other end of the fourth resistor.

[0015] As a further solution of the present invention: The AC mutation detection module includes a fifth resistor, a first capacitor, a sixth resistor, a first potentiometer, a second operational amplifier, a seventh resistor, an eighth resistor and a ninth resistor;

[0016] Preferably, the inverting end of the second operational amplifier is connected to one end of the seventh resistor and connected to the output end of the first operational amplifier, one end of the first capacitor and one end of the ninth resistor through the fifth resistor, the other end of the first capacitor is connected to the non-inverting end of the second operational amplifier and connected to one end of the first potentiometer and the sliding end of the first potentiometer through the sixth resistor, the other end of the first potentiometer is grounded, the output end of the second operational amplifier is connected to the other end of the seventh resistor and the first end of the eighth resistor, and the second end of the eighth resistor is connected to the other end of the ninth resistor.

[0017] As a further solution of the present invention: The isolation detection module includes a first optocoupler, a second optocoupler, a thirteenth resistor, a tenth resistor, a first diode and a second diode; The power supply module includes a power supply device;

[0018] Preferably, the second end of the first optocoupler is connected to the first end of the first optocoupler. The first end of the first optocoupler and the second end of the second optocoupler are both grounded. The third end of the first optocoupler and the third end of the second optocoupler are both connected to the power supply device. The fourth end of the first optocoupler is connected to the anode of the second diode and grounded through the thirteenth resistor. The fourth end of the second optocoupler is connected to the anode of the first diode and grounded through the tenth resistor. The cathode of the first diode is connected to the cathode of the second diode and the signal transmission module.

[0019] As a further solution of the present utility model: The signal transmission module includes a first analog switch; the power quality monitoring module includes a first power supply, a third diode, a fourth diode, an eleventh resistor, a second capacitor, and a power quality monitoring device;

[0020] Preferably, the IN end of the first analog switch is connected to the output end of the first operational amplifier. The OUT end of the first analog switch is connected to the anode of the third diode and the cathode of the fourth diode and is connected to one end of the second capacitor and the first end of the power quality monitoring device through the eleventh resistor. The cathode of the third diode is connected to the first power supply. The anode of the fourth diode, the other end of the second capacitor, and the second end of the power quality monitoring device are all grounded. The CTRL end of the first analog switch is connected to the cathode of the first diode.

[0021] As a further solution of the present utility model: The timing control module includes a fifth diode, a twelfth resistor, a first timer, a third capacitor, a fourth capacitor, and a sixth diode;

[0022] Preferably, the cathode of the fifth diode is connected to one end of the twelfth resistor, the fourth end of the first timer, the eighth end of the first timer, and the power supply device. The anode of the fifth diode is connected to the other end of the twelfth resistor, the sixth end of the first timer, and the second end and grounded through the third capacitor. The first end of the first timer is grounded. The fifth end of the first timer is grounded through the fourth capacitor. The third end of the first timer is connected to the anode of the sixth diode. The cathode of the sixth diode is connected to the CTRL end of the first analog switch.

[0023] Compared with the prior art, the beneficial effects of the present utility model are as follows: The voltage detection circuit for power quality monitoring of the present utility model uses a voltage detection module to detect the voltage of the power grid and perform signal amplification and filtering processing on the detected signal. At the same time, the timing control module transmits the timing control signal, and the signal transmission module transmits the signal output by the voltage detection module to the power quality monitoring module for processing and analysis, recording the initially detected voltage data. After the timing ends, the signal transmission stops, reducing the data processing volume of the power quality monitoring module. And the AC mutation detection module cooperates with the isolation detection module to judge whether there is a voltage mutation in the signal detected by the voltage detection module. When a voltage mutation occurs, the signal transmission module transmits the signal output by the voltage detection module to the power quality monitoring module for processing and analysis again, meeting the voltage detection requirements while reducing the workload of the power quality monitoring module and improving the working efficiency of the power quality monitoring module. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments of the present utility model. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 It is a schematic block diagram of the principle of a voltage detection circuit for power quality monitoring provided by an example of the present utility model.

[0026] Figure 2 It is a circuit diagram of a voltage detection circuit for power quality monitoring provided by an example of the present utility model.

[0027] Figure 3 It is a connection circuit diagram of the timing control module provided by an example of the present utility model. Detailed Embodiments

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present utility model with reference to the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of them. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present utility model.

[0029] In one embodiment, please refer to Figure 1 , a voltage detection circuit for power quality monitoring, including: a voltage detection module 1, an AC mutation detection module 2, a power supply module 3, an isolation detection module 4, a timing control module 5, a signal transmission module 6, and a power quality monitoring module 7;

[0030] Specifically, the voltage detection module 1 is configured to sample the voltage of the power grid, isolate and transmit the sampled signal, amplify and filter the signal, and output a first detection signal;

[0031] The AC mutation detection module 2 is connected to the voltage detection module 1, and is configured to perform a phase shift process on the first detection signal and output a phase-shifted signal, and perform a superimposition process on the phase-shifted signal and the first detection signal, and output a second detection signal when a voltage mutation occurs in the first detection signal;

[0032] The power supply module 3 is configured to provide DC electrical energy;

[0033] The isolation detection module 4 is connected to the power supply module 3 and the AC mutation detection module 2, and is configured to receive the DC electrical energy and the second detection signal, and output a first control signal when the second detection signal is a positive voltage, and output a second control signal when the second detection signal is a negative voltage;

[0034] The timing control module 5 is connected to the power supply module 3, and is configured to set a timing time, and output a third control signal at regular intervals when receiving the DC electrical energy, and stop outputting the third control signal after the timing ends;

[0035] The signal transmission module 6 is connected to the isolation detection module 4, the timing control module 5, the voltage detection module 1, and the power quality monitoring module 7, and is configured to receive the first control signal, the second control signal, or the third control signal and transmit the received first detection signal to the power quality detection module;

[0036] The power quality monitoring module 7 is configured to perform clamping and filtering processes on the first control signal, the second control signal, or the third control signal transmitted by the signal transmission module 6, and transmit the processed signal to the power quality monitoring device.

[0037] In a specific embodiment, the above voltage detection module 1 may adopt a voltage detection circuit composed of a voltage transformer, a resistor, an operational amplifier, etc., which can perform voltage sampling and amplify and filter the sampled signal; the above AC mutation detection module 2 may adopt an AC mutation detection circuit composed of a resistor, a capacitor, an operational amplifier, etc., which can perform a 180-degree phase shift on the signal output by the voltage detection module 1, and superimpose the phase-shifted signal on the signal output by the voltage detection module 1. When the signal output by the voltage detection circuit does not mutate, the potential of the superimposed electric energy is 0V, and when it mutates, it is not 0V; the above power supply module 3 may adopt a power supply circuit composed of a power supply device, which can provide DC electric energy; this DC electric energy has positive and negative values; the above isolation detection module 4 may adopt an isolation detection circuit composed of an optocoupler, a resistor and a diode, which can isolate and detect the voltage state of the signal output by the AC mutation detection module 2; the above timing control module 5 may adopt a timing control circuit composed of a 555 integrated chip, a resistor, a diode and a capacitor, set the timing time, and when powered on, output a high-level signal regularly, and stop outputting the high-level signal after the timing ends; the above signal transmission module 6 may adopt a signal transmission circuit composed of an analog switch, which can transmit the signal output by the voltage detection module 1 to the power quality monitoring module 7; the above power quality monitoring module 7 may adopt a power quality monitoring circuit composed of a diode, a capacitor, a power quality monitoring device, etc., perform clamping and filtering on the input signal, and then be received and processed by the power quality monitoring device.

[0038] In another embodiment, please refer to Figure 1 , Figure 2 and Figure 3 , the voltage detection module 1 includes a detection interface, a first varistor RV1, a first transformer PT1, a first resistor R1, a first operational amplifier OP1, a second resistor R2, a third resistor R3 and a fourth resistor R4;

[0039] Specifically, the first end of the detection interface is connected to the first input end of the first transformer PT1 through the first varistor RV1, the second end of the detection interface is connected to the second input end of the first transformer PT1, the first output end of the first transformer PT1 is connected to the non-inverting end of the first operational amplifier OP1 through the first resistor R1 and grounded through the third resistor R3, the inverting end of the first operational amplifier OP1 is connected to one end of the fourth resistor R4 and connected to the second output end of the first transformer PT1 and the ground terminal through the second resistor R2, and the output end of the first operational amplifier OP1 is connected to the other end of the fourth resistor R4.

[0040] In a specific embodiment, the above first transformer PT1 may be selected as a voltage transformer; the above first operational amplifier OP1 may be selected as an OP07 operational amplifier, which is used to cooperate with the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 to perform signal amplification and signal filtering.

[0041] Furthermore, the AC mutation detection module 2 includes a fifth resistor R5, a first capacitor C1, a sixth resistor R6, a first potentiometer RP1, a second operational amplifier OP2, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9;

[0042] Specifically, the inverting input terminal of the second operational amplifier OP2 is connected to one end of the seventh resistor R7 and is connected to the output terminal of the first operational amplifier OP1, one end of the first capacitor C1, and one end of the ninth resistor R9 through the fifth resistor R5. The other end of the first capacitor C1 is connected to the non-inverting input terminal of the second operational amplifier OP2 and is connected to one end of the first potentiometer RP1 and the sliding terminal of the first potentiometer RP1 through the sixth resistor R6. The other end of the first potentiometer RP1 is grounded. The output terminal of the second operational amplifier OP2 is connected to the other end of the seventh resistor R7 and the first end of the eighth resistor R8, and the second end of the eighth resistor R8 is connected to the other end of the ninth resistor R9.

[0043] In a specific embodiment, the above-mentioned second operational amplifier OP2 can select the OP07 operational amplifier, cooperate with the fifth resistor R5, the first capacitor C1, the sixth resistor R6, the first potentiometer RP1, the seventh resistor R7, and the eighth resistor R8 for phase shift processing, and adjust the resistance value of the first potentiometer RP1 to perform 180-degree phase shift on the input signal.

[0044] Furthermore, the isolation detection module 4 includes a first optocoupler J1, a second optocoupler J2, a thirteenth resistor R13, a tenth resistor R10, a first diode D1, and a second diode D2; the power supply module 3 includes a power supply device;

[0045] Specifically, the second terminal of the first optocoupler J1 is connected to the first terminal of the first optocoupler J1. The first terminal of the first optocoupler J1 and the second terminal of the second optocoupler J2 are both grounded. The third terminal of the first optocoupler J1 and the third terminal of the second optocoupler J2 are both connected to the power supply device. The fourth terminal of the first optocoupler J1 is connected to the anode of the second diode D2 and is grounded through the thirteenth resistor R13. The fourth terminal of the second optocoupler J2 is connected to the anode of the first diode D1 and is grounded through the tenth resistor R10. The cathode of the first diode D1 is connected to the cathode of the second diode D2 and the signal transmission module 6.

[0046] In a specific embodiment, the above-mentioned first optocoupler J1 and second optocoupler J2 can both select the PC817 optocoupler. The first optocoupler J1 detects negative voltage, and the second optocoupler J2 detects positive voltage; the above-mentioned power supply device can select a battery pack.

[0047] Furthermore, the signal transmission module 6 includes a first analog switch IC1; the power quality monitoring module includes a first power supply VCC1, a third diode D3, a fourth diode D4, an eleventh resistor R11, a second capacitor C2, and a power quality monitoring device;

[0048] Specifically, the IN terminal of the first analog switch IC1 is connected to the output terminal of the first operational amplifier OP1. The OUT terminal of the first analog switch IC1 is connected to the anode of the third diode D3 and the cathode of the fourth diode D4, and is connected to one end of the second capacitor C2 and the first terminal of the power quality monitoring device through the eleventh resistor R11. The cathode of the third diode D3 is connected to the first power supply VCC1. The anode of the fourth diode D4, the other end of the second capacitor C2, and the second terminal of the power quality monitoring device are all grounded. The CTRL terminal of the first analog switch IC1 is connected to the cathode of the first diode D1.

[0049] In a specific embodiment, the above-mentioned first analog switch IC1 can be selected as the CD4066 chip; the above-mentioned first power supply VCC1 cooperates with the third diode D3 and the fourth diode D4 for signal clamping processing; the above-mentioned eleventh resistor R11 and the second capacitor C2 perform filtering processing; the above-mentioned power quality monitoring device can be composed of a single-chip microcomputer, a communication chip, etc., and stores, analyzes data, and performs wireless data transmission on the input signal, etc.

[0050] Furthermore, the timing control module 5 includes a fifth diode D5, a twelfth resistor R12, a first timer IC2, a third capacitor C3, a fourth capacitor C4, and a sixth diode D6;

[0051] Specifically, the cathode of the fifth diode D5 is connected to one end of the twelfth resistor R12, the fourth terminal of the first timer IC2, the eighth terminal of the first timer IC2, and the power supply device. The anode of the fifth diode D5 is connected to the other end of the twelfth resistor R12, the sixth terminal of the first timer IC2, and the second terminal, and is grounded through the third capacitor C3. The first terminal of the first timer IC2 is grounded. The fifth terminal of the first timer IC2 is grounded through the fourth capacitor C4. The third terminal of the first timer IC2 is connected to the anode of the sixth diode D6, and the cathode of the sixth diode D6 is connected to the CTRL terminal of the first analog switch IC1.

[0052] In a specific embodiment, the above-mentioned first timer IC2 can be selected as the NE555 chip, and cooperates with the fifth diode D5, the twelfth resistor R12, the third capacitor C3, the fourth capacitor C4, and the sixth diode D6 to perform timing work when powered on.

[0053] In a voltage detection circuit for power quality monitoring in this embodiment, the detection interface is connected to the power grid. The first varistor RV1 and the first current transformer PT1 are used to detect the grid voltage. The first operational amplifier OP1, in cooperation with the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4, amplifies and filters the detected signal, and finally outputs the first detection signal. When starting voltage detection, the power supply device supplies power, and the first timer IC2 is powered on. In cooperation with the sixth diode D6, the fifth diode D5, the twelfth resistor R12, the third capacitor C3, and the fourth capacitor C4, it outputs a high-level signal at regular intervals, making the CTRL terminal of the first analog switch IC1 become high level. The first analog switch IC1 transmits the first detection signal to the power quality monitoring module 7. The power quality monitoring module 7 performs clamping and filtering processing on the first detection signal. Finally, the power quality monitoring device receives and analyzes the data. After the timing ends, the first analog switch IC1 stops transmitting the first detection signal. At the same time, the first detection signal undergoes a 180-degree phase shift through the fifth resistor R5, the sixth resistor R6, the first capacitor C1, the seventh resistor R7, the first potentiometer RP1, the second operational amplifier OP2, and the eighth resistor R8. When the first detection signal does not change suddenly, the voltage between the ninth resistor R9 and the eighth resistor R8 is zero. When the first detection signal changes suddenly, the voltage between the ninth resistor R9 and the eighth resistor R8 will not be zero. When the first detection signal is a positive voltage, the second optocoupler J2 conducts. When the first detection signal is a negative voltage, the first optocoupler J1 conducts. When either the first optocoupler J1 or the second optocoupler J2 conducts, it will control the first analog switch IC1 to transmit the first detection signal to the power quality monitoring device again, and the power quality monitoring device receives and analyzes the data.

[0054] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be encompassed by the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0055] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A voltage detection circuit for power quality monitoring, characterized in that: The voltage detection circuit for power quality monitoring includes: a voltage detection module, an AC mutation detection module, a power supply module, an isolation detection module, a timing control module, a signal transmission module and a power quality monitoring module; The voltage detection module is used to sample the voltage of the power grid and isolate, transmit, amplify and filter the sampled signal and output a first detection signal; The AC mutation detection module is connected to the voltage detection module, and is used to perform phase shift processing on the first detection signal and output the phase shift signal, and is used to perform superposition processing on the phase shift signal and the first detection signal and output the second detection signal when a voltage mutation occurs in the first detection signal; The power module is used to provide direct current power; The isolation detection module is connected to the power module and the AC mutation detection module, and is used to receive DC power and a second detection signal, and output a first control signal when the second detection signal is a positive voltage, and output a second control signal when the second detection signal is a negative voltage; The timing control module is connected to the power supply module, and is used to set the timing time, and when receiving DC power, outputs the third control signal at a fixed time, and stops outputting the third control signal after the timing ends; The signal transmission module is connected to the isolation detection module, the timing control module, the voltage detection module and the power quality monitoring module, and is used to receive the first control signal, the second control signal or the third control signal and transmit the received first detection signal to the power quality detection module; The power quality monitoring module is used to clamp and filter the first control signal, the second control signal or the third control signal transmitted by the signal transmission module, and transmit the processed signal to the power quality monitoring device.

2. A voltage detection circuit for power quality monitoring according to claim 1, characterized in that: The voltage detection module includes a detection interface, a first varistor, a first mutual inductor, a first resistor, a first operational amplifier, a second resistor, a third resistor and a fourth resistor; The first end of the detection interface is connected to the first input end of the first mutual inductor through the first varistor, the second end of the detection interface is connected to the second input end of the first mutual inductor, the first output end of the first mutual inductor is connected to the in-phase end of the first operational amplifier through the first resistor and is grounded through the third resistor, the inverting end of the first operational amplifier is connected to one end of the fourth resistor and is connected to the second output end of the first mutual inductor and the ground through the second resistor, and the output end of the first operational amplifier is connected to the other end of the fourth resistor.

3. A voltage detection circuit for power quality monitoring according to claim 2, characterized in that: The AC mutation detection module includes a fifth resistor, a first capacitor, a sixth resistor, a first potentiometer, a second operational amplifier, a seventh resistor, an eighth resistor and a ninth resistor; The inverting end of the second operational amplifier is connected to one end of the seventh resistor and is connected to the output end of the first operational amplifier, one end of the first capacitor and one end of the ninth resistor through the fifth resistor. The other end of the first capacitor is connected to the non-inverting end of the second operational amplifier and is connected to one end of the first potentiometer and the slider end of the first potentiometer through the sixth resistor. The other end of the first potentiometer is grounded. The output end of the second operational amplifier is connected to the other end of the seventh resistor and the first end of the eighth resistor. The second end of the eighth resistor is connected to the other end of the ninth resistor.

4. A voltage detection circuit for power quality monitoring according to claim 3, characterized in that: The isolation detection module includes a first optical coupler, a second optical coupler, a thirteenth resistor, a tenth resistor, a first diode and a second diode; the power supply module includes a power supply device; The second end of the first optocoupler is connected to the first end of the first optocoupler, the first end of the first optocoupler and the second end of the second optocoupler are both grounded, the third end of the first optocoupler and the third end of the second optocoupler are both connected to the power supply device, the fourth end of the first optocoupler is connected to the anode of the second diode and grounded through the thirteenth resistor, the fourth end of the second optocoupler is connected to the anode of the first diode and grounded through the tenth resistor, and the cathode of the first diode is connected to the cathode of the second diode and the signal transmission module.

5. A voltage detection circuit for monitoring power quality according to claim 4, characterized in that: The signal transmission module includes a first analog switch; the power quality monitoring module includes a first power supply, a third diode, a fourth diode, an eleventh resistor, a second capacitor and a power quality monitoring device; The IN terminal of the first analog switch is connected to the output terminal of the first operational amplifier, the OUT terminal of the first analog switch is connected to the anode of the third diode and the cathode of the fourth diode and is connected to one end of the second capacitor and the first end of the power quality monitoring device through an eleventh resistor, the cathode of the third diode is connected to the first power supply, the anode of the fourth diode, the other end of the second capacitor and the second end of the power quality monitoring device are all grounded, and the CTRL terminal of the first analog switch is connected to the cathode of the first diode.

6. A voltage detection circuit for power quality monitoring according to claim 5, characterized in that: The timing control module includes a fifth diode, a twelfth resistor, a first timer, a third capacitor, a fourth capacitor and a sixth diode; The cathode of the fifth diode is connected to one end of the twelfth resistor, the fourth end of the first timer, the eighth end of the first timer and the power supply device, the anode of the fifth diode is connected to the other end of the twelfth resistor, the sixth end and the second end of the first timer and is grounded through the third capacitor, the first end of the first timer is grounded, the fifth end of the first timer is grounded through the fourth capacitor, the third end of the first timer is connected to the anode of the sixth diode, and the cathode of the sixth diode is connected to the CTRL end of the first analog switch.

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