Research and application analysis of low voltage safety electricity monitoring system based on IOT technology

 

Abstract: Low-voltage safe electricity monitoring system is an important support for ensuring the quality of electricity use and the fundamental basis for enhancing the safety of electricity use. The application of Internet of Things technology can further improve the effectiveness of monitoring. On this basis, this article briefly analyzes the design benchmark and monitoring content of the low-voltage safe electricity monitoring system, and through scientific formulation of system construction plan, building of Internet of Things architecture system, effective introduction of safety protection technology, and accurate information recording, the application level of low-voltage safe electricity monitoring system is improved and its monitoring scope is expanded.

Keywords: IOT technology; low-voltage safe electricity monitoring system; short-circuit fault

 

 

 

 

Preface

Since 2009, the State Grid has started to carry out smart grid projects. As an important product of the third information technology revolution, the Internet of Things technology has been involved in many fields and has played a significant role. During the operation of the power grid, if the Internet of Things technology can be used to achieve safe monitoring of low-voltage electricity consumption, the monitoring quality can be improved on the original basis to ensure the stable operation of the power supply system. Based on this, the transformation plan of the low-voltage safe electricity consumption monitoring system should be fully combined with the Internet of Things technology to realize the monitoring of electricity consumption information with the support of the Internet of Things technology, reduce the system failure rate, and provide electricity.

 

 

Design benchmark for low voltage safety electricity monitoring system

 

 

 

Economical

When designing a low-voltage safe electricity monitoring system, it is necessary to consider whether the modified system has outstanding economic characteristics, so as not to increase the operating burden of the power grid company. At the same time, it should also rely on the Internet of Things technology to provide it with diversified value-added services in the smart grid, so that it can feel the convenience of smart power supply, and can also strengthen the inspection effect of electrical equipment in daily inspection work, thereby keeping the equipment safe in a controllable state, and promoting the development of users’ electricity quality in intelligent monitoring, so as to reduce the cost of manpower input in an effective management environment, including reducing inspection personnel, innovating inspection modes, etc., so as to enable the entire power grid company to have higher comprehensive benefits.

 

 

 

Security

Electricity safety is the basic content of protecting people’s property safety. Low-voltage electricity refers to the electricity use of equipment such as circuit breakers, sockets, leakage switches, hair dryers, etc. When designing a low-voltage safe electricity monitoring system, whether it is the introduction of Internet of Things technology or intelligent management methods, it is necessary to always maintain electricity safety and not cause new safety hazards, so as to maximize the operability of the system. In the past, during troubleshooting, maintenance personnel were often arranged to deal with safety accidents after they occurred. This not only affects the efficiency of troubleshooting, but also threatens the life safety of users. Therefore, in the new design, a “dynamic monitoring” concept should be used to implement “early prevention” for power grid failures, that is, prompts can be given through early warning devices before potential hidden dangers occur, so as to improve maintenance efficiency within the best time, reduce the incidence of dangerous electricity events, and finally achieve stable operation of low-voltage electrical equipment.

 

 

 

Comprehensive

When designing a low-voltage safe electricity monitoring system, it is also necessary to transform the original power grid construction project from a comprehensive perspective such as power quality and resource allocation. In fact, the reason why low-voltage safe electricity monitoring needs to be implemented is, first, to improve the original power supply quality, ensure that users have a good power experience in the use of high-quality electricity, and improve the credibility of power supply companies; second, to propose a scientific configuration plan based on the original human resources and power supply materials, so as to achieve the maximum utilization of resources, avoid idle resources, reduce power supply quality, and even increase the burden on power supply companies and power grid companies. Therefore, the design of a low-voltage safe electricity monitoring system has certain practical significance, and can create favorable conditions for the realization of the current high-quality development goals of the power grid.

 

 

 

 

Monitoring content of low voltage safety electricity monitoring system

 

2.1 Power Quality

The low-voltage safe electricity monitoring system actually uses the Internet of Things platform to achieve the overall management of internal and external power supply systems, and combines online monitoring devices to closely monitor grid-related parameters such as voltage, current, and load rate, thereby reducing the incidence of grid system failures. At the same time, with the support of mobile programs, it can also provide “associated” management services for relevant personnel, that is, whether or not they are at the power supply site, they can implement operations through the monitoring system to eliminate unsafe factors.

At present, the construction of the system has gradually developed in the direction of personalization, which is also a key step to improve the quality of power and power supply services. For example, the quality of electricity used in the aerospace medical field is slightly higher than that of other civilian residences. Once the quality of the power provided is inconsistent with the expected requirements, it will be detrimental to the smooth completion of work tasks in related fields and even reduce the utilization rate of power resources. In addition, substandard power quality can also be affected by power grid pollution events and form power quality problems. Therefore, the monitoring system can be used to keep an eye on changes in power quality at any time.

 

 

 

2.2 Residual current

When using the low-voltage safe electricity monitoring system to monitor residual current, the monitoring results can be used to coordinate the system ground fault and overcurrent protection action, thereby providing a solution for the failure of the circuit breaker to operate normally, ensuring that relevant personnel can effectively monitor the operating status of low-voltage electrical equipment through the monitoring system. The residual current is actually a line where the vector sum of the neutral line and the phase line is not completely eliminated to zero. After the residual current appears, leakage is prone to occur, which in turn poses a threat to the safety of electricity use. Therefore, with the assistance of the monitoring system, the residual current value can be quickly known, so that it can be detected in a direction.

 

 

 

2.3 Line short circuit

If a short circuit occurs in the power grid, the line will heat up sharply, which will reduce the practical performance of the line battery and even weaken the insulation of the outer insulation layer of the line, which is not conducive to the realization of safe power protection. If things go on like this, leakage will occur under high temperature, which will bring hidden dangers to the normal use of low-voltage electrical equipment. The low-voltage safe power monitoring system can monitor the line current value at any time. Once the rated current is exceeded or suddenly increases by thousands of amperes, it will immediately attract the attention of relevant personnel and effectively reduce the occurrence of short-circuit faults.

 

 

 

2.4 Overload current

When monitoring overload current, it is also to increase the safety of low-voltage electricity use. When the current passes through the power grid line, an exothermic reaction will occur, which will cause the wire to heat up. When it exceeds the safe current carrying capacity, it will induce current overload, which is not conducive to the safety protection of the wire, and may even cause a fire in the case of long-term overload current. In this regard, if a low-voltage safe electricity use monitoring system can be designed based on the Internet of Things technology, close attention can be paid to the overload current phenomenon, and the current carrying capacity can be controlled at an appropriate time to prevent the wire from burning and increasing the risk of electricity use. Based on this, the construction of a low-voltage safe electricity use monitoring system is very necessary.

 

 

 

 

3 Application points of low voltage safety electricity monitoring system based on Internet of Things technology

 

3.1 Scientifically formulate system construction plan

When applying IoT technology during the construction of a low-voltage safe electricity monitoring system, it is necessary to scientifically formulate a feasible construction plan, so as to gradually complete the transformation task in accordance with relevant regulations. For example, when monitoring residual current, the “graded protection” method can be used in the system design to weaken the adverse effects of leakage. Among them, the serious consequence caused by residual current is frequent tripping.

In order to effectively control the tripping rate and ensure the quality of electricity for users, Xiaoyi Power Supply Company took relevant measures specifically for residual current in 2019, including regular temperature measurement and maintenance, strengthening operation and maintenance management, etc., thereby reducing the overall tripping rate by 10%. Based on relevant experience, residual current monitoring can be incorporated into the system monitoring content, thereby formulating a feasible construction plan for it, and ultimately preventing users from being disturbed by leakage and unable to obtain a good electricity experience. In this solution, it is necessary to find the root cause of the tripping (leakage) and add a protector to focus on the residual current.

 

In addition, the intermediate protector can be installed in the low-voltage area, and the final protector can be placed in the client. This form of step-by-step protection is not only conducive to reducing the failure rate, but also helps users avoid the risk of power outages. It should be noted that when setting the residual current rating standard, its low action value should be kept at 300mA, and its interval time should not exceed 0.3s, so that during the operation of the low-voltage safe electricity monitoring system, the residual current can be carefully monitored, so that the staff can judge whether there is a hidden danger of power outage at any time according to the residual current monitoring results. In addition, the system also needs to use wireless communication technology to collect power grid operation data in real time and effectively reduce the incidence of co-frequency interference events. With the support of Internet of Things technology, the stability of power grid operation can be increased, and high-quality transmission can be achieved in the current transmission stage to ensure that the power quality used by users meets actual requirements.

 

 

 

3.2 Building an IoT Architecture System

The Internet of Things technology connects the power grid with Internet technology to achieve effective management, control and dynamic monitoring of the power grid with the help of advanced technology. When designing a low-voltage safe power monitoring system based on Internet of Things technology, it is also necessary to create an Internet of Things architecture system based on the specific process of low-voltage power consumption behavior to ensure that the monitoring system can show significant advantages in practice and realize the intelligence of the power grid. chemical monitoring. The Internet of Things architecture system should cover the following four parts: first, the main station centralized monitoring module; second, the power quality monitoring module; third, short circuit monitoring; fourth, communication feedback.

Among the above four important components, the centralized monitoring of the master station is mainly to obtain power quality monitoring data and safe power use behavior information, and verify and identify its potential faults and dangers through scientific analysis, so as to ensure that low-voltage electrical equipment can improve its performance under effective evaluation and avoid sudden safety accidents affecting the safety of users’ power use. In the power quality monitoring link, it can detect abnormal power use behaviors, such as socket mismatch, private disassembly of equipment, wrong wiring, etc. The system can submit the effective information received in this module to the power grid master station and give relevant instructions for control. In short-circuit monitoring, the system specifically monitors the current waveform of the power grid terminal and locates the short-circuit fault with the assistance of computer algorithms. In this way, the power grid master station can obtain short-circuit information in time, which is convenient for the smooth troubleshooting of short-circuit faults. In communication feedback, it can provide reliable basis for the power grid load rate, line loss energy consumption and fault cause, and feed back information to the master station, thereby realizing scientific early warning of power grid lines in integrated management and helping staff to control power quality at any time.

 

 

 

3.3 Effectively introduce security protection technology

When designing a low-voltage safe electricity monitoring system, in addition to ensuring the safety of electricity use and the safety of low-voltage electrical equipment, it is also necessary to use security protection technology to achieve security protection of system communication data to avoid affecting the stability of power grid operation. Specifically, it includes the following:

(1) Authentication security protection. Nowadays, in order to ensure that the system communication data is in a safe protection state, it is often necessary to enhance the system security by “setting keys”. This can reduce the risk of data theft and provide special protection for important data. The protection technology used in authentication is mainly to encrypt the data when transmitting information between low-voltage electrical equipment and the system. Only after passing the authentication can the valid information be obtained smoothly, ensuring that the information will not be lost due to the influence of network technology during the transmission period.

(2) Information exchange protection. When designing a low-voltage safe electricity monitoring system based on the Internet of Things technology, it is also necessary to set up protection devices at the information-related ports, including converting the information into “random numbers” so that the communication content can be known only after it is cracked, thereby avoiding dangerous consequences caused by external interference during information transmission.

From the current practical applications, it can be found that the Internet of Things technology has been widely used in the power industry. For example, a power supply company in Jiangsu Province has specially developed a “user-side demand protection platform”, which uses mobile phone software to monitor the dynamics of data transmission and can also understand the needs of the user side. In this way, while strengthening the data protection effect, it can also improve the quality of power supply services and prompt the user’s needs to be responded to in a timely manner. In addition, the promotion of smart sockets and smart meters has also brought new guidance directions for the application of Internet of Things technology. In order to ensure that the power grid system can achieve low-voltage safe electricity use with the assistance of Internet of Things technology, high-tech should be combined to increase the effectiveness of data security protection, so as to realize the safe transmission of information among multiple entities of the power grid main station, user end, and power supply enterprise, so as to promote the Internet of Things technology to play an important role in the design of low-voltage safe electricity use monitoring system, so as to avoid the risk of incorrect electricity use.

 

 

 

 

3.4 Accurate information recording

When designing a low-voltage safe electricity monitoring system based on the Internet of Things technology, GPRS communication can also be used to accurately record fault information. This will enhance the accuracy of online monitoring of parameters such as power quality, residual current, overload and short circuit, and ensure that the power grid system can provide power to low-voltage electrical equipment during operation, appropriately reduce equipment failure rates, and avoid frequent power outages that affect users’ electricity experience.

Designers can add a “short circuit record” column in the system construction project, and collect three-phase current signals and compare them with the three-phase waveform to understand whether there is a short circuit fault. For example, after a short circuit fault occurs, the B-phase current in the three-phase current will be “0”. Based on this information, it can be determined that a short circuit fault has occurred in the line, and then the conductors and low-voltage circuit breakers can be controlled in a targeted manner to control the overload current below 1200A and above 500A, so as to avoid exceeding the rated range and causing circuit faults.

In addition, a big data supervision platform can be developed based on the advantages of IoT technology. Taking the IoT power platform developed by Ankerui as an example, it specifically includes statistical analysis, hidden danger management, real-time monitoring and other functions. It can make scientific analysis of the hidden danger treatment results and hidden danger types of low-voltage electrical equipment during inspection operations, and determine the fault location under the information navigation function, and record it according to the monitoring results, so that relevant personnel can know the details of the fault at any time in subsequent management work. In the real-time monitoring part, the construction address of the power grid project and the installation status and potential faults of low-voltage electrical equipment can be monitored and managed, and the real-time data can be transmitted to the management department, so as to refer to the suggestions of the management department to make changes to the power grid project. Generally speaking, IoT technology is an important support for realizing intelligent monitoring and integrated management. If it can be applied to the low-voltage safe electricity monitoring system, it will help to ensure the quality of power and reduce the occurrence of faults.

 

 

 

 

4.Introduction and selection of safe electricity cloud platform functions

 

4.1 Introduction to the Safe Power Cloud Platform

The safe electricity cloud management system can monitor, alarm, and record electrical faults such as residual current, equipment temperature, and fault arc in real time, and can be remotely controlled through the cloud. The communication direction between the device and the cloud is not restricted, and it can upload data, transmit instructions, and display real-time status. By analyzing the data uploaded to the cloud, users are provided with relevant data on fire hazards, which can detect problems early and implement investigations to avoid fires. On the other hand, the cloud platform provides ultra-large capacity information storage and stable services, which improves service quality and is of strategic significance to the long-term development of users. In addition, the system uses centralized monitoring to transmit data to the cloud through the 4G network of each node for centralized management and monitoring. The main control terminal is arranged in the city fire brigade, so that the collected information can be uniformly monitored and managed.

 

 

The specific functions are as follows:

(1) The safe electricity use supervision service system includes a safe electricity use management cloud platform, a computer terminal display system, a mobile phone APP, leakage detectors, leakage transformers, current transformers, etc.

 

(2) The safe electricity use supervision service system platform can display the real-time monitoring data and change curves, historical data and change curves, real-time alarm data, etc. of electrical safety parameters such as residual current, temperature, and current. It can also display the number of on-site services, the number of hidden dangers eliminated, the number of hidden dangers not eliminated, the number of unhandled alarms, routine inspections, and product maintenance data in real time. The supervision data can be stored for more than ten years.

 

 

(3) The mobile APP software has both IOS and Android versions. Each alarm record can be called through the mobile APP, so that the power user can be notified as soon as possible in an emergency.

 

 

(4) It can automatically count, analyze and evaluate the electrical safety operation status of each unit and equipment, and display the electrical safety operation analysis report at any time.

 

 

(5) The monitoring and detection terminal products meet the requirements of national laws, regulations and relevant technical standards (GB14287.2 “Residual Current Electrical Fire Monitoring Detector” and GB14287.3 “Temperature Measurement Electrical Fire Monitoring Detector”) and have passed the fire protection 3C certification provided by the National Fire Protection Product Quality Monitoring and Inspection Center.

 

 

(6) The leakage detector can simultaneously detect the residual current, four-way temperature, three-phase current and other parameter values, and can access the safe electricity use supervision system platform through wireless mobile communication network.

 

 

 

4.2 Product Selection

4.2.1 Digital Electricity Meter

 

4.2.2 Arc fault detector

Arc products can monitor the occurrence of circuit fault arcs and provide timely warnings to remind users to handle them and prevent fires caused by arcs.

 

 

4.2.3 Current limiting protector

The model code of Heyi current limiting protector is KP2-VA. It has three current levels and can monitor fault information such as circuit short circuit and overload. When a fault occurs, it can give an early warning and produce an arc extinguishing effect to prevent fires caused by electric arcs.

KP2-VA is used and connected to the safe power platform

The following are the main features of KP2-VA:

Short-circuit protection function: The protector monitors the current of the power line in real time. When a short-circuit fault occurs in the line, it can achieve rapid current limiting protection within 150 microseconds and send out an audible and visual alarm signal.

Overload protection function: When the current of the protected line is overloaded and the overload duration exceeds the action time (3…60 seconds, adjustable), the protector starts current limiting protection and sends out audible and visual alarm signals.

Over-temperature protection function inside the meter. When the operating temperature of the internal components of the protector is too high, the protector starts over-temperature current limiting protection and sends out sound and light alarm signals.

Overvoltage and undervoltage protection function. When the protector detects that the line voltage is overvoltage or undervoltage, the protector will send out an audible and visual alarm signal, and you can pre-set whether to start the current limiting protection.

Distribution cable temperature monitoring function: When the temperature of the monitored cable exceeds the alarm setting value, the protector sends out an audible and visual alarm signal, and you can pre-set whether to start the current limiting protection.

Leakage current monitoring function: When the leakage current of the monitored line exceeds the alarm setting value, the protector will send out an audible and visual alarm signal, and you can pre-set whether to start the current limiting protection.

The protector has 1 RS485 interface and 1 2G wireless communication, which can send data to the background monitoring system to achieve remote monitoring.

 

 

4.2.4 Residual current transformer

 

 

4.2.5 Temperature Sensor

 

The temperature sensor is a thermistor NTC, which provides a temperature monitoring reference of 0-120° and can be used to monitor the temperature of cables or distribution boxes to provide temperature protection.

 

5 Conclusion

In summary, building a low-voltage safe electricity monitoring system with the assistance of the Internet of Things technology can improve the current situation of unstable electricity consumption and frequent failures. Therefore, relevant designers should effectively introduce the Internet of Things technology in system transformation and upgrading to maximize the quality of power supply and create a good electricity environment for the public. They should also start from the aspects of construction plan, Internet of Things architecture system, safety protection technology, accurate information recording, etc., to enable the power grid system to have high safety and reliability in effective monitoring.

 

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