A distributed power distribution network relay protection device

Abstract

The utility model discloses a kind of distributed power distribution network relay protection devices, including main protection module, intelligent instrument module, transformer protection unit and communication interface module, the main protection module includes overcurrent protection circuit, short-circuit quick-break protection circuit, voltage-loss protection circuit and temperature monitoring acquisition circuit.The utility model is cooperated by integrated intelligent instrument and multifunctional protection circuit, realizes the real-time monitoring of distributed power distribution network, direction discrimination and adaptive protection, ultimately through control circuit breaker action, ensure system safety, it is realized that protection fixed value and logic adaptive switching by power direction identification, fundamentally prevent misoperation and refusal to act;And the integrated design of device makes up the deficiency of low-voltage switchgear in the aspect of intelligent protection integration.

Description

Technical Field

[0001] This utility model relates to the field of relay protection technology for power distribution networks, and in particular to a relay protection device for distributed power distribution networks. Background Technology

[0002] With the increasing proportion of distributed power sources connected to distribution networks, the protection configuration of traditional distribution networks is difficult to adapt to new characteristics such as bidirectional power flow and changes in fault current, and is prone to problems such as protection maloperation and failure to operate. Existing relay protection devices are mostly designed for traditional unidirectional power supply systems and lack adaptive protection capabilities after the connection of distributed power sources, especially in terms of integrating intelligent protection and monitoring functions in low-voltage switchgear. In view of the above, this application proposes a relay protection device for distributed power source distribution networks. Utility Model Content

[0003] The purpose of this utility model is to address the shortcomings of existing technologies by proposing a distributed power distribution network relay protection device.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A distributed power distribution network relay protection device includes a main protection module, an intelligent meter module, a transformer protection unit, and a communication interface module. The main protection module includes an overcurrent protection circuit, a short-circuit instantaneous overcurrent protection circuit, an undervoltage protection circuit, and a temperature monitoring and acquisition circuit.

[0006] The main protection module is integrated into the low-voltage switchgear;

[0007] The intelligent meter module has an RS485 communication interface. The intelligent meter module is connected to a communication management unit through the communication interface module to collect current, voltage, power and energy data in real time and upload them to the communication management unit.

[0008] The transformer protection unit is used for temperature monitoring and protection of dry-type transformers, and has alarm and trip functions, and supports remote signal transmission interface;

[0009] The communication interface module supports the RS485 communication protocol and is used to realize data interaction with an external monitoring center.

[0010] Preferably, the overcurrent protection circuit includes a resistor R1. One end of the resistor R1 is electrically connected to the collector of transistor Q1 and one end of capacitor C1. The emitter of transistor Q1 is electrically connected to one end of resistor R4 and grounded. The other end of capacitor C1 is electrically connected to one end of resistor R3 and pin 1 of transistor Q2. The base of transistor Q1 is electrically connected to one end of resistor R2. The other ends of resistor R2 and resistor R3 are both electrically connected to the other end of resistor R4. Pin 2 of transistor Q2 is electrically connected to the other end of resistor R4. Pin 3 of transistor Q2 is connected to the input pin of the intelligent instrument module.

[0011] Preferably, the short-circuit instantaneous protection circuit includes a transistor Q3. Pin 2 of transistor Q3 is connected to pin 1 of the load LOAD. Pin 1 of transistor Q3 is electrically connected to one end of resistor R7 and one end of resistor R5. The other end of resistor R7 is electrically connected to one end of capacitor C2. The other end of capacitor C2 is electrically connected to one end of resistor R6. The other end of resistor R6 is electrically connected to the anode of diode D1 and one end of resistor R9. The other end of resistor R9 is electrically connected to one end of resistor R8. The other ends of resistor R8 and resistor R5 are both grounded. The cathode of diode D1 is electrically connected to pin 2 of transistor Q3.

[0012] Preferably, the undervoltage protection circuit includes transistors Q5 and Q4. The collector of transistor Q5 is electrically connected to the base of transistor Q4. The emitters of transistors Q5 and Q4 are electrically connected to the positive terminal of the same diode D2. The negative terminal of diode D2 is electrically connected to pin 2 of sliding resistor R14. Pin 3 of sliding resistor R14 is electrically connected to the base of transistor Q5. Pin 1 of sliding resistor R14 is electrically connected to one end of resistor R13. The collector of transistor Q5 is electrically connected to... One end of resistor R12 is connected to the collector of transistor Q4, which is connected to the anode of diode D3 and one end of resistor R11. The cathode of diode D2 is connected to one end of resistor R10, and the other end of resistor R10 is connected to one end of switch S1. The other end of switch S1, the other end of resistor R13, the other end of resistor R12, the cathode of diode D3, and the other end of resistor R11 are all connected to a high-level voltage VCC. One end of resistor R10 and the cathode of diode D2 are both grounded.

[0013] Preferably, the temperature monitoring and acquisition circuit includes a chip U1. Pin 1 of chip U1 is electrically connected to pin 4 of operational amplifier U2. Pin 2 of operational amplifier U2 is electrically connected to one end of resistor R14. Pin 3 of operational amplifier U2 is electrically connected to one end of resistor R16 and one end of resistor R15. The other end of resistor R15 is electrically connected to pin 4 of operational amplifier U2 and pin 1 of chip U1. Pin 1 of chip U1 is electrically connected to pin 1 of voltmeter V. The other end of resistor R16 and pin 2 of voltmeter V are both electrically connected to pin 14 of chip U1. Pins 9, 10, 11, 12, 13 and 15 of chip U1 are all grounded. The other end of resistor R14 is connected to the input pin of the intelligent instrument module.

[0014] Preferably, the main protection module, the intelligent instrument module, and the transformer protection unit are all interconnected with the communication interface module via an internal data bus.

[0015] Preferably, the low-voltage switchgear cabinet has an independent instrument room and a relay room. The intelligent instrument module and the communication interface module are installed in the instrument room and connected to the relay room through internal cable trays. The hardware circuit of the main protection module is installed in the relay room in the form of a pluggable module.

[0016] Compared with existing technologies, the beneficial effects of this utility model are:

[0017] 1. The intelligent instrument module provides real-time power direction signals and works in conjunction with overcurrent and undervoltage protection circuits in the main protection module to achieve adaptive switching between protection settings and action logic. This enables accurate differentiation of fault types and effectively prevents protection maloperation or failure to operate in the case of reverse power supply from distributed power sources, greatly improving the selectivity, reliability and stability of the protection and system operation.

[0018] 2. By highly integrating the main protection module, intelligent instrument module, transformer protection unit and communication function into a unified low-voltage switchgear platform, and realizing information sharing through the internal data bus, this integrated design has a compact structure and is easy to maintain. At the same time, the communication interface module realizes remote monitoring of data and remote optimization of protection settings.

[0019] 3. By integrating temperature monitoring and acquisition circuits and independent transformer protection units, real-time monitoring and protection of the thermal status of key equipment are added on the basis of traditional electrical quantity protection. This achieves comprehensive protection against electrical and thermal faults, helps to detect potential problems in advance, avoid equipment damage, and extend equipment life.

[0020] This utility model achieves real-time monitoring, direction identification, and adaptive protection of distributed power distribution networks through the coordinated operation of integrated intelligent instruments and multi-functional protection circuits. Ultimately, it ensures system safety by controlling the operation of circuit breakers. It achieves adaptive switching of protection settings and logic through power direction identification, fundamentally preventing false tripping and failure to trip. Moreover, the integrated design of the device makes up for the deficiencies in the integration of intelligent protection in low-voltage switchgear. Attached Figure Description

[0021] Figure 1 This is a block diagram of a distributed power distribution network relay protection device proposed in this utility model;

[0022] Figure 2 This invention provides a circuit diagram of an overcurrent protection circuit in a distributed power distribution network relay protection device.

[0023] Figure 3 A circuit diagram of a short-circuit instantaneous overcurrent protection circuit in a distributed power distribution network relay protection device proposed in this utility model;

[0024] Figure 4 This is a circuit diagram of an undervoltage protection circuit in a distributed power distribution network relay protection device proposed in this utility model;

[0025] Figure 5 This is a circuit diagram of a temperature monitoring and acquisition circuit in a distributed power distribution network relay protection device proposed in this utility model. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0027] Reference Figure 1-5 A distributed power distribution network relay protection device includes a main protection module, an intelligent meter module, a transformer protection unit, and a communication interface module. The main protection module includes an overcurrent protection circuit, a short-circuit instantaneous overcurrent protection circuit, an undervoltage protection circuit, and a temperature monitoring and acquisition circuit.

[0028] The overcurrent protection circuit includes a resistor R1. One end of the resistor R1 is electrically connected to the collector of transistor Q1 and one end of capacitor C1. The emitter of transistor Q1 is electrically connected to one end of resistor R4 and grounded. The other end of capacitor C1 is electrically connected to one end of resistor R3 and pin 1 of transistor Q2. The base of transistor Q1 is electrically connected to one end of resistor R2. The other ends of resistor R2 and resistor R3 are both electrically connected to the other end of resistor R4. Pin 2 of transistor Q2 is electrically connected to the other end of resistor R4. Pin 3 of transistor Q2 is connected to the input pin of the smart instrument module.

[0029] The overcurrent protection circuit operates as follows: When the monitored line current increases, the input signal is sent to the base of transistor Q1 via resistor R2 to control its conduction level, thereby charging capacitor C1. The charging speed reflects the current magnitude. The voltage across capacitor C1 serves as the basis for delay judgment. When this voltage reaches the threshold of the subsequent trigger circuit, transistor Q2 is driven to conduct, and the trip preparation signal is output from its pin 3 to the intelligent instrument module. During this process, resistors R1 and R4 form a sampling and biasing network, and resistor R3 adjusts the feedback. The entire circuit achieves inverse time delay characteristics through RC charging and discharging, and finally converts the overcurrent fault into a logic signal that can be recognized by the intelligent module through the state change of transistor Q2, thus providing a direct basis for the system's adaptive protection judgment.

[0030] The short-circuit instantaneous protection circuit includes transistor Q3. Pin 2 of transistor Q3 is connected to pin 1 of the load LOAD. Pin 1 of transistor Q3 is electrically connected to one end of resistor R7 and one end of resistor R5. The other end of resistor R7 is electrically connected to one end of capacitor C2. The other end of capacitor C2 is electrically connected to one end of resistor R6. The other end of resistor R6 is electrically connected to the positive terminal of diode D1 and one end of resistor R9. The other end of resistor R9 is electrically connected to one end of resistor R8. The other ends of resistor R8 and resistor R5 are both grounded. The negative terminal of diode D1 is electrically connected to pin 2 of transistor Q3.

[0031] The operation of the short-circuit instantaneous overcurrent protection circuit is as follows: When a short-circuit fault occurs in the line, the instantaneous large current signal quickly charges capacitor C2 through resistors R5 and R7, and at the same time forms another fast path through resistor R6 and diode D1; the voltage of capacitor C2 rises sharply at the moment of the fault, directly driving transistor Q3 to conduct quickly, thereby immediately energizing the load LOAD connected to pin 2. During this process, the voltage divider network formed by resistors R8 and R9 is used to set the action threshold, while diode D1 ensures the rapid transmission and reverse isolation of the signal. The entire circuit utilizes the instantaneous charging characteristic of capacitor C2 to achieve a millisecond-level response to the short-circuit current, and finally completes the fast overcurrent protection.

[0032] The undervoltage protection circuit includes transistors Q5 and Q4. The collector of transistor Q5 is electrically connected to the base of transistor Q4. The emitters of transistors Q5 and Q4 are electrically connected to the positive terminal of the same diode D2. The negative terminal of diode D2 is electrically connected to pin 2 of sliding resistor R14. Pin 3 of sliding resistor R14 is electrically connected to the base of transistor Q5. Pin 1 of sliding resistor R14 is electrically connected to one end of resistor R13. The collector of transistor Q5 is electrically connected to... One end of resistor R12 is connected to the collector of transistor Q4, which is electrically connected to the positive terminal of diode D3 and one end of resistor R11. The negative terminal of diode D2 is electrically connected to one end of resistor R10. The other end of resistor R10 is electrically connected to one end of switch S1. The other end of switch S1, the other end of resistor R13, the other end of resistor R12, the negative terminal of diode D3, and the other end of resistor R11 are all electrically connected to a high-level voltage VCC. One end of resistor R10 and the negative terminal of diode D2 are both grounded.

[0033] The operation of the undervoltage protection circuit is as follows: When the system voltage is normal, the high-level VCC provides base current to transistor Q5 through resistor R13 and sliding resistor R14, causing it to saturate and conduct. This, in turn, pulls down the base potential of transistor Q4 and cuts it off, resulting in no action signal at the output terminal. Once the system voltage drops or falls significantly, transistor Q5 turns off due to the disappearance of base current. At this time, the high-level VCC provides base current to transistor Q4 through resistor R12, causing it to conduct rapidly. The driving current flows from the collector through diode D3 to the output relay, issuing a trip command. During this process, sliding resistor R14 is used to accurately set the voltage threshold for undervoltage action, diode D2 ensures potential matching, and diode D3 prevents current reversal. The entire circuit achieves continuous monitoring of system voltage and rapid and reliable protection against undervoltage faults through the switching of the conduction states of transistors Q5 and Q4.

[0034] The temperature monitoring and acquisition circuit includes a chip U1. Pin 1 of chip U1 is electrically connected to pin 4 of operational amplifier U2. Pin 2 of operational amplifier U2 is electrically connected to one end of resistor R14. Pin 3 of operational amplifier U2 is electrically connected to one end of resistor R16 and one end of resistor R15. The other end of resistor R15 is electrically connected to pin 4 of operational amplifier U2 and pin 1 of chip U1. Pin 1 of chip U1 is electrically connected to pin 1 of voltmeter V. The other end of resistor R16 and pin 2 of voltmeter V are both electrically connected to pin 14 of chip U1. Pins 9, 10, 11, 12, 13 and 15 of chip U1 are all grounded. The other end of resistor R14 is connected to the input pin of the intelligent instrument module.

[0035] The operation of the temperature monitoring and acquisition circuit is as follows: The resistance signal of the temperature sensor is sent to the operational amplifier U2 for signal amplification and conditioning after passing through the reference network composed of resistors R15 and R16; the amplified analog voltage signal is sent to pin 1 of chip U1 for analog-to-digital conversion and logic processing. Chip U1 converts the voltage value corresponding to the temperature into readable data. One path of this data drives the voltmeter V for local display, and the other path transmits it to the input pin of the intelligent instrument module through resistor R14, providing a standard temperature monitoring signal to the upper-level system, thereby realizing a complete monitoring function from temperature sensing, signal conditioning, digital processing to local display and remote transmission.

[0036] The main protection module is integrated into the low-voltage switchgear;

[0037] The smart meter module has an RS485 communication interface. The smart meter module is connected to the communication management unit through the communication interface module to collect current, voltage, power and energy data in real time and upload them to the communication management unit.

[0038] The transformer protection unit is used for temperature monitoring and protection of dry-type transformers. It has alarm and trip functions and supports remote signal transmission interface.

[0039] The communication interface module supports the RS485 communication protocol for data exchange with an external monitoring center.

[0040] The main protection module, intelligent instrument module, and transformer protection unit are all interconnected with the communication interface module through an internal data bus. The low-voltage switchgear cabinet has an independent instrument room and a relay room. The intelligent instrument module and communication interface module are installed in the instrument room and connected to the relay room through internal cable trays. The hardware circuit of the main protection module is installed in the relay room in the form of a pluggable module.

[0041] This utility model achieves real-time monitoring, direction identification, and adaptive protection of distributed power distribution networks through the coordinated operation of integrated intelligent instruments and multi-functional protection circuits. Ultimately, it ensures system safety by controlling the operation of circuit breakers. It achieves adaptive switching of protection settings and logic through power direction identification, fundamentally preventing false tripping and failure to trip. Moreover, the integrated design of the device makes up for the deficiencies in the integration of intelligent protection in low-voltage switchgear.

[0042] It should be noted that the EM600LCD-H type smart meter is preferred for the smart meter module. The smart meter module collects the analog electrical parameters of the power distribution circuit in real time through the internal current transformer and voltage sampling circuit. After being converted into digital signals by the analog-to-digital converter, the embedded processor calculates high-precision data such as current, voltage, power, energy and power direction. The processing results are simultaneously uploaded to the communication management unit and transmitted to the main protection module through the RS485 communication interface, providing panoramic data support for the system's adaptive protection and remote monitoring. Its specific operating principle is existing technology and will not be described separately here.

[0043] Working Principle: During operation, the intelligent instrument module collects the system current in real time through the current transformer. The output power direction signal is sent to the overcurrent protection circuit. The overcurrent protection circuit consists of transistors Q1 and Q2, external resistors R1, R2, R3, R4, and capacitor C1, forming a signal conditioning and logic judgment unit. When the detected current value exceeds the set threshold and the power direction is determined to be a reverse fault, the circuit state changes and a trip signal is output. At the same time, the short-circuit instantaneous protection circuit, consisting of transistor Q3, capacitor C2, and diode D1, forms an instantaneous action loop that quickly responds to the sudden change signal generated by the short-circuit current, triggering the output relay without delay. The undervoltage protection circuit monitors and controls the bus voltage through transistors Q4 and Q5 and sliding resistor R14. When the voltage drops, it changes the conduction state and issues an undervoltage trip command. The temperature monitoring and acquisition circuit relies on chip U1 and operational amplifier U2 to process the signal from the temperature sensor, realizing overheat alarm and protection.

[0044] In addition, the output signals of each protection circuit work together through internal interlocking and logic to act on the shunt trip coil of the low-voltage incoming circuit breaker of the power distribution system, driving it to trip quickly. At the same time, all fault and status information are uploaded to the communication management unit through the communication interface module, thereby realizing the coordination of local adaptive protection and remote monitoring.

[0045] In summary, by working together with integrated smart meters and multi-functional protection circuits, real-time monitoring, direction determination, and adaptive protection of distributed power distribution networks are achieved, and system safety is ensured by controlling the operation of circuit breakers.

[0046] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A relay protection device for distributed power generation distribution networks, characterized in that, It includes a main protection module, an intelligent instrument module, a transformer protection unit, and a communication interface module. The main protection module includes an overcurrent protection circuit, a short-circuit instantaneous overcurrent protection circuit, an undervoltage protection circuit, and a temperature monitoring and acquisition circuit. The main protection module is integrated into the low-voltage switchgear; The intelligent meter module has an RS485 communication interface. The intelligent meter module is connected to a communication management unit through the communication interface module to collect current, voltage, power and energy data in real time and upload them to the communication management unit. The transformer protection unit is used for temperature monitoring and protection of dry-type transformers, and has alarm and trip functions, and supports remote signal transmission interface; The communication interface module supports the RS485 communication protocol and is used to realize data interaction with an external monitoring center.

2. The distributed power supply network relay protection device according to claim 1, characterized in that, The overcurrent protection circuit includes a resistor R1. One end of the resistor R1 is electrically connected to the collector of transistor Q1 and one end of capacitor C1. The emitter of transistor Q1 is electrically connected to one end of resistor R4 and grounded. The other end of capacitor C1 is electrically connected to one end of resistor R3 and pin 1 of transistor Q2. The base of transistor Q1 is electrically connected to one end of resistor R2. The other ends of resistor R2 and resistor R3 are both electrically connected to the other end of resistor R4. Pin 2 of transistor Q2 is electrically connected to the other end of resistor R4. Pin 3 of transistor Q2 is connected to the input pin of the intelligent instrument module.

3. The distributed power supply network relay protection device according to claim 1, characterized in that, The short-circuit instantaneous protection circuit includes a transistor Q3. Pin 2 of transistor Q3 is connected to pin 1 of the load LOAD. Pin 1 of transistor Q3 is electrically connected to one end of resistor R7 and one end of resistor R5. The other end of resistor R7 is electrically connected to one end of capacitor C2. The other end of capacitor C2 is electrically connected to one end of resistor R6. The other end of resistor R6 is electrically connected to the anode of diode D1 and one end of resistor R9. The other end of resistor R9 is electrically connected to one end of resistor R8. The other ends of resistor R8 and resistor R5 are both grounded. The cathode of diode D1 is electrically connected to pin 2 of transistor Q3.

4. A distributed power supply distribution network relay protection device according to claim 1, characterized in that, The undervoltage protection circuit includes transistors Q5 and Q4. The collector of transistor Q5 is electrically connected to the base of transistor Q4. The emitters of transistors Q5 and Q4 are electrically connected to the positive terminal of the same diode D2. The negative terminal of diode D2 is electrically connected to pin 2 of sliding resistor R14. Pin 3 of sliding resistor R14 is electrically connected to the base of transistor Q5. Pin 1 of sliding resistor R14 is electrically connected to one end of resistor R13. The collector of transistor Q5 is electrically connected to... One end of resistor R12 is connected to the collector of transistor Q4, which is electrically connected to the positive terminal of diode D3 and one end of resistor R11. The negative terminal of diode D2 is electrically connected to one end of resistor R10. The other end of resistor R10 is electrically connected to one end of switch S1. The other end of switch S1, the other end of resistor R13, the other end of resistor R12, the negative terminal of diode D3, and the other end of resistor R11 are all electrically connected to a high-level voltage VCC. One end of resistor R10 and the negative terminal of diode D2 are both grounded.

5. A distributed power supply distribution network relay protection device according to claim 1, characterized in that, The temperature monitoring and acquisition circuit includes a chip U1. Pin 1 of chip U1 is electrically connected to pin 4 of operational amplifier U2. Pin 2 of operational amplifier U2 is electrically connected to one end of resistor R14. Pin 3 of operational amplifier U2 is electrically connected to one end of resistor R16 and one end of resistor R15. The other end of resistor R15 is electrically connected to pin 4 of operational amplifier U2 and pin 1 of chip U1. Pin 1 of chip U1 is electrically connected to pin 1 of voltmeter V. The other end of resistor R16 and pin 2 of voltmeter V are both electrically connected to pin 14 of chip U1. Pins 9, 10, 11, 12, 13 and 15 of chip U1 are all grounded. The other end of resistor R14 is connected to the input pin of the intelligent instrument module.

6. A distributed power supply distribution network relay protection device according to claim 1, characterized in that, The main protection module, intelligent instrument module, and transformer protection unit are all interconnected with the communication interface module via an internal data bus.

7. A distributed power supply distribution network relay protection device according to claim 1, characterized in that, The low-voltage switchgear cabinet has independent instrument room and relay room. The intelligent instrument module and communication interface module are installed in the instrument room and connected to the relay room through internal cable trays. The hardware circuit of the main protection module is installed in the relay room in the form of pluggable modules.

Images