Microgrid relay protection method

Abstract

The invention discloses a micro-grid relay protection method. A micro-grid relay protection device is included. The micro-grid relay protection equipment comprises a distributed power generation and energy storage protection device, an automatic reclosing device, a pilot protection device, a static rapid separation switch, a microcomputer relay protection device, a current transformer, a voltage transformer and a measurement relay; the micro-grid relay protection equipment is maintained and calibrated, including cleaning, wiring fastening, connection state checking and ensuring that the equipment is in a good state, and meanwhile, periodic calibration is performed on sensor and mutual inductor measurement equipment to ensure the measurement accuracy of the sensor and mutual inductor measurement equipment. According to the relay protection method with the micro-grid, a current transformer, a voltage transformer and a measuring relay are installed, high-precision and high-sensitivity sensors and transformers are selected, it is ensured that collected current and voltage electrical quantity data are accurate and reliable, and then large difference of fault currents in a well pattern operation mode and an off-grid operation mode is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field related to microgrids, and in particular to a microgrid relay protection method. Background Art

[0002] A microgrid is a small power grid composed of distributed power generation equipment, energy storage equipment and loads, which has strong independence and autonomy. Since the power supply and load in the microgrid are distributed, the relay protection must take into account its particularity. The main goal of microgrid relay protection is to correctly distinguish internal and external faults, disturbances or abnormal operation of the microgrid, so as to quickly isolate the fault, reduce the scope of the fault, and send signals to ensure the safe operation of the microgrid and its equipment; The magnitude and direction of short-circuit current in existing microgrids change with the access of distributed power sources, which affects the coordination relationship of traditional distribution network protection. In particular, there is a large difference in fault current between the well-grid and off-grid operation modes, which brings challenges to relay protection; In order to solve the above-mentioned defects, a microgrid relay protection method and device with publication number CN110224382B is proposed. It sets a genetic algorithm real-time prediction model, predicts the current situation of the next cycle in real time based on the historical current data in the microgrid, and then compares the predicted value with the actual sampled data in the microgrid to determine whether there is a short-circuit fault in the microgrid. First, through the real-time prediction of the genetic algorithm, it solves the problem that the traditional overcurrent protection relies solely on the setting of fixed values ​​to determine whether there is a short-circuit fault, which often leads to protection failure, and greatly improves the sensitivity and timeliness of the relay protection; secondly, it can meet the comprehensive protection needs of microgrids of 400V and below when operating in an isolated network; thirdly, it can adapt to the switching of the microgrid between the two working states of the isolated network and the grid-connected network; finally, it can identify various faults in the microgrid and make correct responses to ensure the safe and stable operation of the microgrid; In the actual use of the above-mentioned device, although the detection accuracy can be improved by setting up a genetic algorithm real-time prediction model, its genetic algorithm real-time prediction model requires a large number of training samples to learn the fault characteristics and protection action rules of the power grid. As the scale of the power grid expands, more and newer training samples are needed, which increases the difficulty of data collection and processing.

[0003] So we proposed a microgrid relay protection method to solve the problems raised above. Summary of the invention

[0004] The purpose of the present invention is to provide a microgrid relay protection method to solve the problem proposed in the above background technology that the real-time prediction model of genetic algorithms on the current market requires a large number of training samples to learn the fault characteristics and protection action laws of the power grid. As the scale of the power grid expands, more and newer training samples are needed, which increases the difficulty of data collection and processing.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solutions: a microgrid relay protection method, comprising a microgrid relay protection device; Also includes: The microgrid relay protection equipment includes a distributed generation and energy storage protection device, an automatic reclosing device, a longitudinal protection device, a static fast disconnect switch, a microcomputer relay protection device, a current transformer, a voltage transformer and a measuring relay.

[0006] Preferably, the current transformer, voltage transformer and measuring relay are high-precision, high-sensitivity sensors and transformers to ensure that the collected current and voltage electrical quantity data are accurate and reliable.

[0007] Preferably, the microgrid relay protection equipment is maintained and calibrated, including cleaning, tightening wiring, and checking connection status to ensure that the equipment is in good condition. At the same time, sensors and transformer measuring equipment are periodically calibrated to ensure their measurement accuracy.

[0008] Preferably, the microgrid relay protection device adopts standard communication protocols and interfaces so as to be seamlessly integrated and work in coordination with the control system and communication system of the microgrid.

[0009] Preferably, the microgrid relay protection device adopts a redundant design and a double protection configuration to improve the reliability and safety of the equipment.

[0010] Preferably, the microgrid relay protection device is electrically isolated from the microgrid to prevent short circuit or electric shock accidents caused by improper electrical connection.

[0011] Preferably, the method comprises the following steps: A1: Analyze the microgrid structure, understand the configuration and connection methods of distributed power sources (such as solar energy, wind energy), energy storage devices, energy conversion devices, loads, and monitoring and protection devices in the microgrid, and evaluate the voltage and current variation patterns of the microgrid under normal operation and fault conditions; A2: According to the structure and operation characteristics of the microgrid, determine the required protection type (overcurrent protection, differential protection, directional protection, and determine the coverage, sensitivity and speed requirements of the protection.

[0012] Preferably, the method comprises the following steps: Q1: Set voltage protection criteria. Set voltage protection criteria at the microgrid bus level to detect changes in bus voltage. When the bus voltage changes meet the protection criteria (the voltage drop exceeds the set threshold), an alarm signal is sent to the control system, and a fault line is determined. An alarm signal is also sent to the microgrid monitoring system or operator to detect and handle the fault in a timely manner. Q2: Current transformers, voltage transformers and measuring relays collect current and voltage electrical quantity data in the microgrid in real time.

[0013] Preferably, the method comprises the following steps: S1: Different measures are taken for different types of faults. For faults in double-ended power supply line sections, current differential protection or impedance-type directional pilot protection is used. Current differential protection determines the fault location by comparing the current difference at both ends of the line. Impedance-type directional pilot protection identifies faults in the positive direction of the line by setting impedance measurement elements at both ends of the line and transmits fault signals through the power line carrier channel. For faults in load branches with only one side connected to the power supply, overcurrent information is used to meet protection requirements. S2: According to the collected electrical quantity information and the set protection criteria, set a reasonable tripping logic. When the tripping conditions are met, the relay protection device should act quickly to cut off the faulty line or equipment to prevent the fault from expanding; S3: After the fault is removed, take appropriate measures to restore the normal operation of the system according to the operation status and needs of the microgrid.

[0014] Preferably, the method comprises the following steps: M1: Use the microgrid monitoring system to monitor the operating status of the microgrid and the working conditions of the protection devices in real time, detect and handle abnormal situations in time, and ensure the safe and stable operation of the microgrid; M2: Regularly maintain and inspect microgrid relay protection equipment to ensure that it performs well and works properly, and promptly repair and handle any defects and problems found to improve the reliability and accuracy of protection; M3: Record and analyze the fault process, including the time, location, and type of fault, and evaluate the performance of microgrid relay protection equipment, including action time, accuracy, and reliability; M4: Improve and optimize the relay protection device based on the fault records and analysis results, as well as the protection performance evaluation results; M5: Establish a spare parts and inventory management system so that the microgrid relay protection device can be quickly replaced and repaired when a failure occurs. At the same time, regularly inspect and test the spare parts to ensure that their quality and performance meet the requirements.

[0015] (1) The current transformer, voltage transformer and measuring relay in the present invention are selected from sensors and transformers with high precision and high sensitivity to ensure that the collected current and voltage electrical quantity data are accurate and reliable, thereby avoiding large differences in fault current between the well-grid and off-grid operation modes; (2) The microgrid relay protection device of the present invention adopts standard communication protocols and interfaces so as to be seamlessly integrated and work in coordination with the control system and other devices of the microgrid communication system, thereby improving applicability; (3) The microgrid relay protection device in the present invention adopts a redundant design and a double set of protection configuration to improve the reliability and safety of the equipment. The redundant design enables the system to respond more flexibly when facing complex faults by providing protection devices and functional channels, thereby improving the overall safety of the system; (4) In the present invention, there is electrical isolation between the microgrid relay protection device and the microgrid to prevent short circuit or electric shock accidents caused by improper electrical connection. The electrical isolation can isolate the high voltage circuit from the low voltage circuit or the human body, effectively avoiding the occurrence of electric shock accidents and reducing the risks during the maintenance process; (5) The microgrid relay protection equipment in the present invention is maintained and calibrated, including cleaning, tightening wiring, and checking connection status to ensure that the equipment is in good condition. At the same time, the sensor and transformer measurement equipment are periodically calibrated to ensure their measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the operating process structure of the present invention DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Embodiment 1:

[0018] The present invention provides a technical solution, a microgrid relay protection method, comprising the following steps: Microgrid relay protection equipment; also includes: the microgrid relay protection equipment includes distributed generation and energy storage protection devices, automatic reclosing devices, longitudinal protection devices, static fast disconnect switches, microcomputer relay protection devices, current transformers, voltage transformers and measuring relays. Current transformers, voltage transformers and measuring relays select high-precision and high-sensitivity sensors and transformers to ensure that the collected current and voltage electrical quantity data are accurate and reliable. The microgrid relay protection equipment is maintained and calibrated, including cleaning, tightening wiring, and checking connection status to ensure that the equipment is in good condition. At the same time, the sensor and transformer measurement equipment are periodically calibrated to ensure their measurement accuracy; A1: Analyze the microgrid structure, understand the configuration and connection methods of distributed power sources (such as solar energy, wind energy), energy storage devices, energy conversion devices, loads, and monitoring and protection devices in the microgrid, and evaluate the voltage and current variation patterns of the microgrid under normal operation and fault conditions; A2: According to the structure and operation characteristics of the microgrid, determine the required protection type (overcurrent protection, differential protection, directional protection, and determine the coverage, sensitivity and speed requirements of the protection; Q1: Set voltage protection criteria. Set voltage protection criteria at the microgrid bus level to detect changes in bus voltage. When the bus voltage changes meet the protection criteria (the voltage drop exceeds the set threshold), an alarm signal is sent to the control system, and a fault line is determined. An alarm signal is also sent to the microgrid monitoring system or operator to detect and handle the fault in a timely manner. Q2: Current transformers, voltage transformers and measuring relays collect current and voltage electrical quantity data in the microgrid in real time; Embodiment 2:

[0019] The present invention provides a technical solution, a microgrid relay protection method, comprising the following steps: Maintain and calibrate the microgrid relay protection equipment, including cleaning, tightening wiring, and checking connection status to ensure that the equipment is in good condition. At the same time, periodically calibrate the sensors and transformer measurement equipment to ensure their measurement accuracy. The microgrid relay protection equipment uses standard communication protocols and interfaces to seamlessly integrate and work with other equipment in the microgrid control system and communication system; Q1: Set voltage protection criteria. Set voltage protection criteria at the microgrid bus level to detect changes in bus voltage. When the bus voltage changes meet the protection criteria (the voltage drop exceeds the set threshold), an alarm signal is sent to the control system, and a fault line is determined. An alarm signal is also sent to the microgrid monitoring system or operator to detect and handle the fault in a timely manner. Q2: Current transformers, voltage transformers and measuring relays collect current and voltage electrical quantity data in the microgrid in real time; S1: Different measures are taken for different types of faults. For faults in double-ended power supply line sections, current differential protection or impedance-type directional pilot protection is used. Current differential protection determines the fault location by comparing the current difference at both ends of the line. Impedance-type directional pilot protection identifies faults in the positive direction of the line by setting impedance measurement elements at both ends of the line and transmits fault signals through the power line carrier channel. For faults in load branches with only one side connected to the power supply, overcurrent information is used to meet protection requirements. S2: According to the collected electrical quantity information and the set protection criteria, set a reasonable tripping logic. When the tripping conditions are met, the relay protection device should act quickly to cut off the faulty line or equipment to prevent the fault from expanding; S3: After the fault is removed, take corresponding measures to restore the normal operation of the system according to the operation status and needs of the microgrid. M1: Use the microgrid monitoring system to monitor the operation status of the microgrid and the working status of the protection device in real time, discover and handle abnormal situations in time, and ensure the safe and stable operation of the microgrid; M2: Regularly maintain and inspect microgrid relay protection equipment to ensure that it performs well and works properly, and promptly repair and handle any defects and problems found to improve the reliability and accuracy of protection; M3: Record and analyze the fault process, including the time, location, and type of fault, and evaluate the performance of microgrid relay protection equipment, including action time, accuracy, and reliability; M4: Improve and optimize the relay protection device based on the fault records and analysis results, as well as the protection performance evaluation results; M5: Establish spare parts and inventory management system so that the microgrid relay protection device can be quickly replaced and repaired when it fails. At the same time, regularly inspect and test spare parts to ensure that their quality and performance meet the requirements; Embodiment three:

[0020] The present invention provides a technical solution, a microgrid relay protection method, comprising the following steps: The microgrid relay protection equipment adopts redundant design and double protection configuration to improve the reliability and safety of the equipment. The microgrid relay protection equipment is electrically isolated from the microgrid to prevent short circuit or electric shock accidents caused by improper electrical connection. Q1: Set voltage protection criteria. Set voltage protection criteria at the microgrid bus level to detect changes in bus voltage. When the bus voltage changes meet the protection criteria (the voltage drop exceeds the set threshold), an alarm signal is sent to the control system, and a fault line is determined. An alarm signal is also sent to the microgrid monitoring system or operator to detect and handle the fault in a timely manner. Q2: Current transformers, voltage transformers and measuring relays collect current and voltage electrical quantity data in the microgrid in real time; M1: Use the microgrid monitoring system to monitor the operating status of the microgrid and the working conditions of the protection devices in real time, detect and handle abnormal situations in time, and ensure the safe and stable operation of the microgrid; M2: Regularly maintain and inspect microgrid relay protection equipment to ensure that it performs well and works properly, and promptly repair and handle any defects and problems found to improve the reliability and accuracy of protection; M3: Record and analyze the fault process, including the time, location, and type of fault, and evaluate the performance of microgrid relay protection equipment, including action time, accuracy, and reliability; M4: Improve and optimize the relay protection device based on the fault records and analysis results, as well as the protection performance evaluation results; M5: Establish a spare parts and inventory management system so that the microgrid relay protection device can be quickly replaced and repaired when a failure occurs. At the same time, regularly inspect and test the spare parts to ensure that their quality and performance meet the requirements.

[0021] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to replace some of the technical features therein. Any modification, replacement, and improvement made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A microgrid relay protection method, comprising a microgrid relay protection device; It is characterized in that Also includes: The microgrid relay protection equipment includes a distributed generation and energy storage protection device, an automatic reclosing device, a longitudinal protection device, a static fast disconnect switch, a microcomputer relay protection device, a current transformer, a voltage transformer and a measuring relay.

2. A microgrid relay protection method according to claim 1, characterized in that: The current transformer, voltage transformer and measuring relay are selected from high-precision and high-sensitivity sensors and transformers to ensure that the collected current and voltage electrical quantity data are accurate and reliable.

3. A microgrid relay protection method according to claim 1, characterized in that: The microgrid relay protection equipment is maintained and calibrated, including cleaning, tightening wiring, and checking connection status to ensure that the equipment is in good condition. At the same time, sensors and mutual inductor measuring equipment are periodically calibrated to ensure their measurement accuracy.

4. A microgrid relay protection method according to claim 1, characterized in that: The microgrid relay protection device adopts standard communication protocols and interfaces so as to be seamlessly integrated and work in coordination with the control system and communication system of the microgrid.

5. A microgrid relay protection method according to claim 1, characterized in that: The microgrid relay protection device adopts a redundant design and a double set of protection configuration to improve the reliability and safety of the device.

6. A microgrid relay protection method according to claim 1, characterized in that: The microgrid relay protection device is electrically isolated from the microgrid to prevent short circuit or electric shock accidents caused by improper electrical connection.

7. A microgrid relay protection method according to claim 1, characterized in that: The following steps are involved: A1: Analyze the microgrid structure, understand the configuration and connection methods of distributed power sources (such as solar energy, wind energy), energy storage devices, energy conversion devices, loads, and monitoring and protection devices in the microgrid, and evaluate the voltage and current variation patterns of the microgrid under normal operation and fault conditions; A2: According to the structure and operation characteristics of the microgrid, determine the required protection type (overcurrent protection, differential protection, directional protection, and determine the coverage, sensitivity and speed requirements of the protection.

8. A microgrid relay protection method according to claim 1, characterized in that: The following steps are involved: Q1: Set voltage protection criteria. Set voltage protection criteria at the microgrid bus level to detect changes in bus voltage. When the bus voltage changes meet the protection criteria (the voltage drop exceeds the set threshold), an alarm signal is sent to the control system, and a fault line is determined. An alarm signal is also sent to the microgrid monitoring system or operator to detect and handle the fault in a timely manner. Q2: Current transformers, voltage transformers and measuring relays collect current and voltage electrical quantity data in the microgrid in real time.

9. A microgrid relay protection method according to claim 1, characterized in that: The following steps are involved: S1: Different measures are taken for different types of faults. For faults in double-ended power supply line sections, current differential protection or impedance-type directional pilot protection is used. Current differential protection determines the fault location by comparing the current difference at both ends of the line. Impedance-type directional pilot protection identifies faults in the positive direction of the line by setting impedance measurement elements at both ends of the line and transmits fault signals through the power line carrier channel. For faults in load branches with only one side connected to the power supply, overcurrent information is used to meet protection requirements. S2: According to the collected electrical quantity information and the set protection criteria, set a reasonable tripping logic. When the tripping conditions are met, the relay protection device should act quickly to cut off the faulty line or equipment to prevent the fault from expanding; S3: After the fault is removed, take appropriate measures to restore the normal operation of the system according to the operation status and needs of the microgrid.

10. A microgrid relay protection method according to claim 1, characterized in that: The following steps are involved: M1: Use the microgrid monitoring system to monitor the operating status of the microgrid and the working conditions of the protection devices in real time, detect and handle abnormal situations in time, and ensure the safe and stable operation of the microgrid; M2: Regularly maintain and inspect microgrid relay protection equipment to ensure that it performs well and works properly, and promptly repair and handle any defects and problems found to improve the reliability and accuracy of protection; M3: Record and analyze the fault process, including the time, location, and type of fault, and evaluate the performance of microgrid relay protection equipment, including action time, accuracy, and reliability; M4: Improve and optimize the relay protection device based on the fault records and analysis results, as well as the protection performance evaluation results; M5: Establish a spare parts and inventory management system so that the microgrid relay protection device can be quickly replaced and repaired when a failure occurs. At the same time, regularly inspect and test the spare parts to ensure that their quality and performance meet the requirements.

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