Zero sequence current detection system

What is AI technical title?
AI technical title is built by Patsnap AI team. It summarizes the technical point description of the patent document.
The integration of a flexible current transformer, signal amplification, A/D conversion, and validity detection modules addresses the precision and reliability issues in zero sequence current detection, ensuring accurate and reliable detection of zero sequence currents in three-phase four-wire power systems.

CN223107913UActive Publication Date: 2025-07-15BAODING KEWEI ELECTRIC POWER SCI & TECHCO LTD

View PDF 0 Cites 0 Cited by

Patent Information

Application Number: CN202422155105.6
Authority / Receiving Office: CN · China
Patent Type: Utility models(China)
Current Assignee / Owner
Filing Date: 2024-09-03
Publication Date: 2025-07-15
Estimated Expiration: 2034-09-03

AI Technical Summary

Technical Problem

The traditional zero-sequence current detection method is difficult to meet the detection needs of modern power systems for high precision and high reliability, especially due to the installation position of the current transformer and the stability of long-term operation.

Method used

The integration of flexible current transformer, signal amplification module, A/D conversion module, main control module and effectiveness detection module is adopted. The neutral current is detected through the flexible current transformer, the signal amplification module amplifies weak signals, and the A/D conversion module is digitally processed. The effectiveness detection module regularly verifies the performance of the current transformer.

Benefits of technology

It realizes high-precision and high-reliability detection of zero-sequence current in three-phase and four-wire system, enhances the flexibility and adaptability of the system, ensures the accuracy and reliability of the detection, prevents missed detection caused by equipment aging or failure, and ensures the safe and stable operation of the power system.

✦ Generated by Eureka AI based on patent content.

Smart Images

Figure CN223107913U_ABST

Patent Text Reader

Abstract

The utility model provides a zero-sequence current detection system, and belongs to the technical field of power detection. The zero sequence current detection system comprises a current transformer, a signal amplification module, an A / D conversion module, a main control module and an effectiveness detection module. The current transformer is used for detecting zero line current and is connected with a first end of the signal amplification module, a second end of the signal amplification module is connected with a first end of the A / D conversion module, and a second end of the A / D conversion module is connected with the main control module; the main control module is connected with the effectiveness detection module; the effectiveness detection module is used for detecting the performance of the current transformer; the effectiveness detection module comprises a switching circuit and a current simulation circuit; the first end of the switching circuit is connected with the master control module, and the second end of the switching circuit is connected with the current analog circuit which is used for generating analog current. The problem that a traditional zero-sequence current detection means is difficult to meet the requirements of a modern power system for high-precision and high-reliability detection can be solved.

Need to check novelty before this filing date? Find Prior Art

Description

Technical Field

[0001] The present disclosure relates to the technical field of power detection, and particularly to a zero-sequence current detection system. Background Art

[0002] In a power system, the three-phase four-wire power supply method is widely used. However, when the three-phase load is unbalanced or a grounding fault occurs, zero-sequence current will be generated, and this current may pose a threat to the safe and stable operation of the power system. Traditional zero-sequence current detection methods are often limited by the installation location, accuracy, and long-term operation stability of current transformers, and it is difficult to meet the requirements of modern power systems for high-precision and high-reliability detection. Summary of the Utility Model

[0003] Embodiments of the present disclosure provide a zero-sequence current detection system to solve the problem that traditional zero-sequence current detection means are difficult to meet the requirements of modern power systems for high-precision and high-reliability detection.

[0004] Embodiments of the present disclosure provide a zero-sequence current detection system, including: a current transformer, a signal amplification module, an A / D conversion module, a main control module, and a validity detection module;

[0005] The current transformer is used to detect the zero-line current. The current transformer is connected to the first end of the signal amplification module. The second end of the signal amplification module is connected to the first end of the A / D conversion module. The second end of the A / D conversion module is connected to the main control module;

[0006] The main control module is connected to the validity detection module. The validity detection module is used to detect the performance of the current transformer;

[0007] The validity detection module includes a switch circuit and a current simulation circuit;

[0008] The first end of the switch circuit is connected to the main control module. The second end of the switch circuit is connected to the current simulation circuit. The current simulation circuit is used to generate an analog current.

[0009] In an exemplary embodiment of the present disclosure, the current transformer includes: a flexible current transformer;

[0010] The flexible current transformer is used to detect the zero-line current.

[0011] In an exemplary embodiment of the present disclosure, the signal amplification module includes: resistor R5, capacitor C2, operational amplifier U3, resistor R7, and resistor R8;

[0012] The first end of the resistor R5 is connected to the first end of the flexible current transformer, the second end of the resistor R5 is connected to the second end of the flexible current transformer, the first end of the capacitor C2 is connected to the first end of the resistor R5, the second end of the capacitor C2 is connected to the non-inverting input terminal of the operational amplifier U3, the inverting input terminal of the operational amplifier U3 is grounded through the resistor R7, the output terminal of the operational amplifier U3 is connected to the inverting input terminal of the operational amplifier U3 through the resistor R8, and the output terminal of the operational amplifier U3 is connected to the first end of the A / D conversion module.

[0013] In an exemplary embodiment of the present disclosure, the A / D conversion module includes: a resistor R10, a resistor R11, a resistor R12, and an operational amplifier U4;

[0014] The first end of the resistor R10 is connected to the output terminal of the operational amplifier U3, the second end of the resistor R10 is connected to the non-inverting input terminal of the operational amplifier U4, the inverting input terminal of the operational amplifier U4 is connected to the VCC power supply through the resistor R11, the inverting input terminal of the operational amplifier U4 is grounded through the resistor R12, and the output terminal of the operational amplifier U4 is connected to the main control module.

[0015] In an exemplary embodiment of the present disclosure, the A / D conversion module further includes: an optocoupler U5, a resistor R9, a triode Q3, and a resistor R14;

[0016] The first input terminal of the optocoupler U5 is connected to the output terminal of the operational amplifier U4, the second input terminal of the optocoupler U5 is grounded, the first output terminal of the optocoupler U5 is connected to the VDD power supply through the resistor R9, the second output terminal of the optocoupler U5 is connected to the base of the triode Q3, the collector of the triode Q3 is connected to the VDD power supply, the emitter of the triode Q3 is grounded through the resistor R14, and the emitter of the triode Q3 is connected to the main control module.

[0017] In an exemplary embodiment of the present disclosure, the switch circuit includes: a relay SW1;

[0018] The relay SW1 is controlled by the main control module, and the relay SW1 is connected to the current simulation circuit.

[0019] In an exemplary embodiment of the present disclosure, the current simulation circuit includes: a transformer H1, a rheostat RP1, a diode D1, a capacitor C1, a resistor R1, a resistor R2, an operational amplifier U2, a resistor R3, a rheostat RP2, a triode Q1, a resistor R4, a thyristor Q2, and an inductor L2;

[0020] The first end of the relay SW1 is connected to the first end of the transformer H1, the second end of the relay SW1 is connected to the first anode of the thyristor Q2, and the second anode of the thyristor Q2 is connected to the second end of the transformer H1 through the inductor L2;

[0021] The second end of the relay SW1 is grounded through the variable resistor RP1, the anode of the diode D1 is connected to the second end of the relay SW1, the cathode of the diode D1 is grounded through the capacitor C1, the cathode of the diode D1 is connected to the non-inverting input end of the operational amplifier U2 through the resistor R1, the inverting input end of the operational amplifier U2 is grounded through the resistor R2, the output end of the operational amplifier U2 is connected to the inverting input end of the operational amplifier U2 through the resistor R3, the output end of the operational amplifier U2 is connected to the first end of the variable resistor RP2, the second end of the variable resistor RP2 is grounded, the sliding end of the variable resistor RP2 is connected to the base of the transistor Q1, the collector of the transistor Q1 is connected to the VCC power supply, the emitter of the transistor Q1 is grounded through the resistor R4, and the emitter of the transistor Q1 is connected to the control electrode of the thyristor Q2.

[0022] In an exemplary embodiment of the present disclosure, it further includes: a protection module and a communication module;

[0023] The protection module is connected to the main control module;

[0024] The main control module is connected to the terminal through the communication module.

[0025] The beneficial effects of the zero-sequence current detection system provided by the embodiment of the present disclosure are:

[0026] The disclosed embodiment realizes high-precision and high-reliability detection of zero-sequence current in a three-phase four-wire system by integrating flexible current transformers, signal amplification, A / D conversion, main control and validity detection modules. The application of flexible current transformers enhances the flexibility and adaptability of the disclosed embodiment, ensuring effective detection in different installation environments. At the same time, the signal amplification and A / D conversion modules ensure accurate amplification and digital processing of weak signals, improving detection accuracy. More importantly, the validity detection module regularly verifies the accuracy of the current transformer through analog current injection and performance evaluation, effectively preventing false detection and missed detection due to equipment aging or failure, and ensuring the safe and stable operation of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the accompanying drawings required for use in the embodiments or the description of the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0028] Figure 1 is a schematic structural diagram of a zero-sequence current detection system provided by an embodiment of the present disclosure;

[0029] Figure 2 is a circuit diagram of a zero-sequence current detection system provided by an embodiment of the present disclosure;

[0030] Figure 3 is a circuit diagram of a validity detection module provided by an embodiment of the present disclosure. Specific Embodiments

[0031] To enable those skilled in the art of this technology to better understand this solution, the following clearly describes the technical solutions in the embodiments of this solution in conjunction with the accompanying drawings in the embodiments of this solution. Obviously, the described embodiments are part of the embodiments of this solution, rather than all of the embodiments. Based on the embodiments in this solution, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this solution.

[0032] The term "including" and any other variations in the description of the specification, claims, and the above accompanying drawings of this solution mean "including but not limited to", and are intended to cover non-exclusive inclusion, not limited to the examples listed in the text. In addition, terms such as "first" and "second" are used to distinguish different objects, rather than to describe a specific order.

[0033] The following describes the implementation of the present disclosure in detail in conjunction with specific accompanying drawings:

[0034] Figure 1 is a schematic structural diagram of a zero-sequence current detection system provided by an embodiment of the present disclosure. Referring to Figure 1 , the zero-sequence current detection system includes: a current transformer, a signal amplification module, an A / D conversion module, a main control module, and a validity detection module; the current transformer is used to detect the zero-line current, the current transformer is connected to the first end of the signal amplification module, the second end of the signal amplification module is connected to the first end of the A / D conversion module, and the second end of the A / D conversion module is connected to the main control module; the main control module is connected to the validity detection module, and the validity detection module is used to detect the performance of the current transformer; the validity detection module includes a switching circuit and a current simulation circuit; the first end of the switching circuit is connected to the main control module, the second end of the switching circuit is connected to the current simulation circuit, and the current simulation circuit is used to generate an analog current.

[0035] In an embodiment of the present disclosure, the current transformer includes: a flexible current transformer; the flexible current transformer is used to detect the neutral line current.

[0036] In this embodiment, a flexible current transformer can be used as the current transformer. The flexible current transformer is used to detect the zero-sequence current in a three-phase power system. The zero-sequence current refers to the current flowing through the neutral line (neutral wire) in a three-phase four-wire system when the three-phase load is unbalanced or a grounding fault occurs. Under normal circumstances, if the three-phase load is balanced, there should be no current or only a very small current on the neutral line. If a large current is detected on the neutral line, this usually means that the three-phase load is unbalanced or there is a grounding fault, and both of these situations may cause the zero-sequence current to appear.

[0037] The flexible current transformer can be installed on the neutral line to adapt to different installation environments. It is used to detect the neutral line current in a three-phase four-wire system. When the three-phase load is unbalanced or a grounding fault occurs, a zero-sequence current will be generated. Based on the principle of electromagnetic induction, the flexible current transformer converts the zero-sequence current on the neutral line into a smaller induced current output according to a certain ratio. The induced current output by the flexible current transformer is usually very weak and requires a signal amplification module for amplification processing. The first end of the signal amplification module receives the weak signal from the flexible current transformer and amplifies it through the internal amplification circuit to improve the strength and stability of the signal. The amplified signal is output from the second end of the signal amplification module and connected to the first end of the A / D conversion module. The A / D conversion module converts the analog signal into a digital signal for the main control module to process. Its first end receives the amplified analog signal output from the signal amplification module and converts the analog signal into a digital signal through the internal analog-to-digital conversion circuit. The converted digital signal is output from the second end of the A / D conversion module and connected to the main control module. The main control module is used to receive the digital signal output from the A / D conversion module and analyze and process it. The main control module can detect, calculate, and judge the neutral line current. When a large current is detected on the neutral line, it can be judged that the three-phase load is unbalanced or there is a grounding fault.

[0038] In the actual application process, the working environment of the power system is relatively complex, and the flexible current transformer may fail during long-term use. In order to ensure that the flexible current transformer can stably and reliably detect the zero-sequence current in the power system, in this embodiment, the main control module is also connected to an effectiveness detection module, which can regularly control the operation of the effectiveness detection module. The effectiveness detection module is used to detect the performance of the flexible current transformer to ensure its normal operation and accuracy. It mainly consists of a switch circuit and a current simulation circuit.

[0039] The first end of the switch circuit is connected to the main control module and receives the control signal of the main control module. When the performance test of the flexible current transformer is required, the main control module sends a control signal to the switch circuit to turn on the switch circuit. The second end of the switch circuit is connected to the current simulation circuit, and the current simulation circuit is connected to the system after being turned on. The current simulation circuit is used to generate simulated current. When the switch circuit is turned on, the current simulation circuit generates a specific simulated current, which is injected into the system through the switch circuit to simulate the zero line current. At this time, other modules in this embodiment, such as the flexible current transformer, the signal amplification module, the A / D conversion module and the main control module, can detect and process the simulated current. By comparing the detection result of the simulated current with the preset standard value, it can be judged whether the performance of the flexible current transformer is normal.

[0040] It can be concluded from the above that this embodiment realizes high-precision and high-reliability detection of zero-sequence current in a three-phase four-wire system by integrating flexible current transformers, signal amplification, A / D conversion, main control and validity detection modules. The application of flexible current transformers enhances the flexibility and adaptability of this embodiment, ensuring effective detection in different installation environments. At the same time, the signal amplification and A / D conversion modules ensure accurate amplification and digital processing of weak signals, thereby improving detection accuracy. More importantly, the validity detection module regularly verifies the accuracy of the current transformer through analog current injection and performance evaluation, effectively preventing false detection and missed detection due to equipment aging or failure, and ensuring the safe and stable operation of the power system.

[0041] like Figure 2 As shown, in one embodiment of the present disclosure, the signal amplification module includes: a resistor R5, a capacitor C2, an operational amplifier U3, a resistor R7 and a resistor R8; the first end of the resistor R5 is connected to the first end of the flexible current transformer, the second end of the resistor R5 is connected to the second end of the flexible current transformer, the first end of the capacitor C2 is connected to the first end of the resistor R5, the second end of the capacitor C2 is connected to the in-phase input terminal of the operational amplifier U3, the inverting input terminal of the operational amplifier U3 is grounded through the resistor R7, the output terminal of the operational amplifier U3 is connected to the inverting input terminal of the operational amplifier U3 through the resistor R8, and the output terminal of the operational amplifier U3 is connected to the first end of the A / D conversion module.

[0042] In this embodiment, resistor R5 can convert the current signal into a voltage signal. Capacitor C2 mainly plays a coupling role, allowing the AC signal to pass through while blocking the DC signal to prevent the DC signal from having an adverse effect on the subsequent circuit. In this way, the neutral line current signal processed by resistor R5 and capacitor C2 is transmitted to the non-inverting input terminal of operational amplifier U3. Operational amplifier U3 constitutes a negative feedback amplifier circuit, which is used to amplify the voltage signal on resistor R5 and can also improve the stability of the circuit. Finally, the output terminal of operational amplifier U3 is connected to the first terminal of the A / D conversion module to transmit the amplified neutral line current signal to the A / D conversion module for analog-to-digital conversion, so that the subsequent main control module can process and analyze it.

[0043] In this embodiment, through the collaborative action of resistors, capacitors, and operational amplifiers, the signal amplification module amplifies the weak neutral line current signal detected by the flexible current transformer, providing a stable and amplified signal for subsequent signal processing and analysis.

[0044] As Figure 2 shown, in an embodiment of the present disclosure, the A / D conversion module includes: resistor R10, resistor R11, resistor R12, and operational amplifier U4; the first terminal of resistor R10 is connected to the output terminal of operational amplifier U3, the second terminal of resistor R10 is connected to the non-inverting input terminal of operational amplifier U4, the inverting input terminal of operational amplifier U4 is connected to the VCC power supply through resistor R11, the inverting input terminal of operational amplifier U4 is grounded through resistor R12, and the output terminal of operational amplifier U4 is connected to the main control module.

[0045] In this embodiment, resistors R11 and R12 constitute a voltage division circuit. The voltage on resistor R12 is taken as the reference voltage and applied to the inverting input terminal of operational amplifier U4. The non-inverting input terminal of operational amplifier U4 receives the output voltage of operational amplifier U3. When there is a zero-sequence current in the power system, operational amplifier U3 outputs an alternating voltage signal. This alternating voltage signal is sent to the non-inverting input terminal of operational amplifier U4 and compared with the reference voltage at the inverting input terminal of operational amplifier U4, causing operational amplifier U4 to output a pulse signal, thereby converting the analog signal into a digital signal. When the main control module detects the pulse signal output by operational amplifier U4, it indicates that there is a zero-sequence current in the power system. Furthermore, effective maintenance measures can be taken.

[0046] In this embodiment, the A / D conversion module processes the analog signal from the signal amplification module through the combination of resistors and operational amplifiers and transmits the processed signal to the main control module, laying a foundation for the digital signal processing and analysis of the entire zero-sequence current detection system.

[0047] As Figure 2As shown, in an embodiment of the present disclosure, the A / D conversion module further includes: an optocoupler U5, a resistor R9, a triode Q3, and a resistor R14; the first input terminal of the optocoupler U5 is connected to the output terminal of the operational amplifier U4, the second input terminal of the optocoupler U5 is grounded, the first output terminal of the optocoupler U5 is connected to the VDD power supply through the resistor R9, the second output terminal of the optocoupler U5 is connected to the base of the triode Q3, the collector of the triode Q3 is connected to the VDD power supply, the emitter of the triode Q3 is grounded through the resistor R14, and the emitter of the triode Q3 is connected to the main control module.

[0048] In this embodiment, the first input terminal of the optocoupler U5 is connected to the output terminal of the operational amplifier U4 to receive the pulse signal output by the operational amplifier U4. When the light emission intensity of the light-emitting diode inside the optocoupler U5 changes due to the pulse signal, the conduction degree of the photosensitive triode inside the optocoupler also changes accordingly. The second input terminal of the optocoupler U5 is grounded to provide a reference potential for the normal operation of the optocoupler. The first output terminal of the optocoupler U5 is connected to the VDD power supply through the resistor R9, and the resistor R9 plays a current-limiting role to protect the subsequent circuit. The second output terminal of the optocoupler U5 is connected to the base of the triode Q3 to transmit the signal processed by the optocoupler to the triode Q3.

[0049] The triode Q3 plays a role in level conversion in this process. The collector of the triode Q3 is connected to the VDD power supply to provide a working voltage for the triode. The emitter of the triode Q3 is grounded through the resistor R14, and the resistor R14 plays a role in stabilizing the working state of the triode and current limiting. When the signal output by the second output terminal of the optocoupler U5 causes the base potential of the triode Q3 to change, the conduction degree of the triode Q3 also changes accordingly, so that a signal after level conversion is output at the emitter.

[0050] Finally, the emitter of the triode Q3 is connected to the main control module to transmit the processed signal to the main control module for further digital signal processing and analysis. In this way, the extended part of the A / D conversion module realizes the isolated transmission, amplification, and level conversion of signals, providing a more reliable guarantee for the accurate detection and effective maintenance of the zero-sequence current detection system.

[0051] As Figure 3 shown, in an embodiment of the present disclosure, the switch circuit includes: a relay SW1; the relay SW1 is controlled by the main control module, and the relay SW1 is connected to the current analog circuit.

[0052] In this embodiment, the relay SW1 is controlled by the main control module. When it is necessary to perform performance detection on the current transformer, the main control module issues a control signal. This control signal is received by the relay SW1, and the relay operates according to the state of the control signal. When the main control module issues an enabling signal, the relay SW1 closes, thereby connecting the current simulation circuit to the system. The current simulation circuit can generate an analog current to simulate the situation of the neutral line current. At this time, other modules in the system, such as the current transformer, signal amplification module, A / D conversion module, etc., will detect and process the analog current.

[0053] In this embodiment, through the switching action of the relay SW1, the connection and disconnection of the current simulation circuit can be conveniently controlled. During the normal zero-sequence current detection process, the relay SW1 remains in the open state, and the system detects the actual neutral line current through the current transformer. When it is necessary to perform performance detection on the current transformer, the main control module controls the relay SW1 to close, connecting the current simulation circuit to the system to verify the accuracy and reliability of the current transformer.

[0054] As Figure 3 shown, in an embodiment of the present disclosure, the current simulation circuit includes: a transformer H1, a rheostat RP1, a diode D1, a capacitor C1, a resistor R1, a resistor R2, an operational amplifier U2, a resistor R3, a rheostat RP2, a triode Q1, a resistor R4, a thyristor Q2, and an inductor L2; the first end of the relay SW1 is connected to the first end of the transformer H1, the second end of the relay SW1 is connected to the first anode of the thyristor Q2, and the second anode of the thyristor Q2 is connected to the second end of the transformer H1 through the inductor L2; the second end of the relay SW1 is grounded through the rheostat RP1, the anode of the diode D1 is connected to the second end of the relay SW1, the cathode of the diode D1 is grounded through the capacitor C1, the cathode of the diode D1 is connected to the non-inverting input terminal of the operational amplifier U2 through the resistor R1, the inverting input terminal of the operational amplifier U2 is grounded through the resistor R2, the output terminal of the operational amplifier U2 is connected to the inverting input terminal of the operational amplifier U2 through the resistor R3, the output terminal of the operational amplifier U2 is connected to the first end of the rheostat RP2, the second end of the rheostat RP2 is grounded, the sliding end of the rheostat RP2 is connected to the base of the triode Q1, the collector of the triode Q1 is connected to the VCC power supply, the emitter of the triode Q1 is grounded through the resistor R4, and the emitter of the triode Q1 is connected to the control electrode of the thyristor Q2.

[0055] In this embodiment, the main control module can periodically send control instructions to the relay SW1, such as sending a control instruction once every three months. After receiving the control instruction, the relay SW1 closes.

[0056] The transformer H1 can be a current transformer, a voltage transformer, etc. In this embodiment, a current transformer is used as the transformer H1.

[0057] The current transformer H1 is used to collect the current on the live wire and convert the large current signal on the live wire into a small current output. The variable resistor RP1 is used to convert the current output by the current transformer H1 into a voltage signal. The diode D1 and the capacitor C1 form a rectifying and filtering circuit, which is used to convert the AC voltage on the variable resistor RP1 into a DC voltage signal and send it to the non-inverting input terminal of the operational amplifier U2. The operational amplifier U2 forms an amplifying circuit, and the operational amplifier U2 is used to amplify the DC voltage. After amplification, a voltage is generated on the variable resistor RP2. The voltage at the sliding end of the variable resistor RP2 can turn on the triode Q1, and a voltage signal is generated on the resistor R4, thereby turning on the thyristor Q2. At this time, the current transformer H1 forms a loop through the thyristor Q2 and the inductor L2 in sequence, and an AC current signal is generated on the inductor L2. This current signal is used as the signal of the simulated zero-sequence current. If the flexible current transformer can detect the current signal on the inductor L2, it indicates that the flexible current transformer is working properly. If the flexible current transformer does not detect the current signal on the inductor L2, it indicates that the flexible current transformer may have a fault.

[0058] In this embodiment, the current simulation circuit integrates components such as current transformers, rectifying and filtering, amplification, and thyristor control to achieve precise acquisition, conversion, and analog output of the live wire current, effectively simulating the zero-sequence current signal, and providing a reliable current source for the performance detection of the flexible current transformer. This not only simplifies the detection process, improves the accuracy and efficiency of detection, but also realizes the long-term detection of the current transformer through regular automatic control, timely discovers and warns of potential faults, and ensures the stable operation and safety of the power system.

[0059] As Figure 1 shown, in an embodiment of the present disclosure, it further includes: a protection module and a communication module; the protection module is connected to the main control module; the main control module is communicatively connected to the terminal through the communication module.

[0060] In this embodiment, the protection module plays an important role in ensuring the safety of the zero-sequence current detection system. When there is a zero-sequence current in the power system, the connection between the power grid and the electrical equipment should be disconnected in a timely manner to avoid damage to the electrical equipment.

[0061] The communication module enables the zero-sequence current detection system to interact with external terminals for data. The main control module transmits the detected zero-sequence current data and the operating state information of the system to the terminal through the communication module, such as a computer, a smart phone, etc. At the same time, the terminal can also send control commands to the main control module through the communication module to achieve remote monitoring and management of the system. The communication module can adopt various communication methods, such as Bluetooth, Wi-Fi, wired network, etc., and is selected according to the requirements of the actual application scenario. The communication module transmits data through a specific communication protocol to ensure the accuracy and reliability of the data.

[0062] In this embodiment, the protection module and the communication module respectively undertake important tasks of protecting the system security and realizing communication with external terminals in the zero-sequence current detection system, improving the stability, reliability and manageability of the system.

[0063] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than limiting them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A zero-sequence current detection system, characterized in that It includes: a current transformer, a signal amplification module, an A / D conversion module, a main control module, and a validity detection module; The current transformer is used to detect the zero-line current. The current transformer is connected to the first end of the signal amplification module. The second end of the signal amplification module is connected to the first end of the A / D conversion module. The second end of the A / D conversion module is connected to the main control module; The main control module is connected to the validity detection module. The validity detection module is used to detect the performance of the current transformer; The validity detection module includes a switch circuit and a current simulation circuit; The first end of the switch circuit is connected to the main control module. The second end of the switch circuit is connected to the current simulation circuit. The current simulation circuit is used to generate an analog current.

2. The zero-sequence current detection system according to claim 1, characterized in that, The current transformer includes: a flexible current transformer; The flexible current transformer is used to detect the zero-line current.

3. The zero-sequence current detection system according to claim 2, wherein The signal amplification module includes: resistor R5, capacitor C2, operational amplifier U3, resistor R7, and resistor R8; The first end of resistor R5 is connected to the first end of the flexible current transformer. The second end of resistor R5 is connected to the second end of the flexible current transformer. The first end of capacitor C2 is connected to the first end of resistor R5. The second end of capacitor C2 is connected to the non-inverting input terminal of operational amplifier U3. The inverting input terminal of operational amplifier U3 is grounded through resistor R7. The output terminal of operational amplifier U3 is connected to the inverting input terminal of operational amplifier U3 through resistor R8. The output terminal of operational amplifier U3 is connected to the first end of the A / D conversion module.

4. The zero-sequence current detection system according to claim 3, characterized in that, The A / D conversion module includes: resistor R10, resistor R11, resistor R12, and operational amplifier U4; The first end of resistor R10 is connected to the output terminal of operational amplifier U3. The second end of resistor R10 is connected to the non-inverting input terminal of operational amplifier U4. The inverting input terminal of operational amplifier U4 is connected to the VCC power supply through resistor R11. The inverting input terminal of operational amplifier U4 is grounded through resistor R12. The output terminal of operational amplifier U4 is connected to the main control module.

5. The zero-sequence current detection system according to claim 4, wherein The A / D conversion module further includes: optocoupler U5, resistor R9, triode Q3, and resistor R14; The first input terminal of optocoupler U5 is connected to the output terminal of operational amplifier U4. The second input terminal of optocoupler U5 is grounded. The first output terminal of optocoupler U5 is connected to the VDD power supply through resistor R9. The second output terminal of optocoupler U5 is connected to the base of triode Q3. The collector of triode Q3 is connected to the VDD power supply. The emitter of triode Q3 is grounded through resistor R14. The emitter of triode Q3 is connected to the main control module.

6. The zero-sequence current detection system according to claim 1, characterized in that, The switch circuit includes: relay SW1; Relay SW1 is controlled by the main control module. Relay SW1 is connected to the current simulation circuit.

7. The zero-sequence current detection system according to claim 6, characterized in that, The current simulation circuit includes: transformer H1, rheostat RP1, diode D1, capacitor C1, resistor R1, resistor R2, operational amplifier U2, resistor R3, rheostat RP2, triode Q1, resistor R4, thyristor Q2, and inductor L2; The first end of the relay SW1 is connected to the first end of the mutual inductor H1, the second end of the relay SW1 is connected to the first anode of the thyristor Q2, and the second anode of the thyristor Q2 is connected to the second end of the mutual inductor H1 through the inductor L2; The second end of the relay SW1 is grounded through the rheostat RP1. The anode of the diode D1 is connected to the second end of the relay SW1. The cathode of the diode D1 is grounded through the capacitor C1. The cathode of the diode D1 is connected to the non-inverting input terminal of the operational amplifier U2 through the resistor R1. The inverting input terminal of the operational amplifier U2 is grounded through the resistor R2. The output terminal of the operational amplifier U2 is connected to the inverting input terminal of the operational amplifier U2 through the resistor R3. The output terminal of the operational amplifier U2 is connected to the first end of the rheostat RP2. The second end of the rheostat RP2 is grounded. The sliding end of the rheostat RP2 is connected to the base of the triode Q1. The collector of the triode Q1 is connected to the VCC power supply. The emitter of the triode Q1 is grounded through the resistor R4. The emitter of the triode Q1 is connected to the control electrode of the thyristor Q2.

8. The zero-sequence current detection system according to claim 1, characterized in that, It further includes: A protection module and a communication module; The protection module is connected to the main control module; The main control module is communicatively connected to the terminal through the communication module.