Summary:With the development of the times, an increasing number of devices are becoming intelligent, and substation equipment is no exception. In intelligent substations, analyzing their basic structure and operational modes allows for the implementation of online temperature measurement technology for 10kV high-voltage switchgears. This article, under this premise, mainly introduces the key aspects of the 10kV high-voltage switchgear online temperature measurement technology and analyzes its actual application process, hoping to provide reference.
Keywords:Intelligent Substation; Temperature Measurement; High Voltage
Introduction
The intelligent substation is primarily an electrical equipment that allocates power directly to the 10kV distribution network. Under longer operating conditions, some high-voltage switchgear may carry a current of up to 4000A. Factors such as high operating currents, misalignment of internal connectors, loose fixed and moving contacts, and substandard materials can significantly increase resistance, leading to severe internal heating in the 10kV high-voltage switchgear. China has strict regulations for 10kV high-voltage switchgear (the products provided must comply with national certification documents or equivalent valid proof): exceeding the allowed temperature limits can severely impact the operational efficiency of the 10kV high-voltage switchgear, potentially causing accidents. Therefore, employing effective online temperature measurement technology to accurately and in real-time monitor the internal temperature of the 10kV high-voltage switchgear is crucial.
Basic Content and Features of Online Temperature Measurement Technology for 10kV High-Voltage Switchgear
Typically, the body of a 10kV high-voltage switchgear cabinet is fully enclosed, with a very limited internal space. This space houses numerous devices, resulting in a short safety distance between electrical equipment, which significantly increases the difficulty of temperature measurement. Traditional temperature measurement techniques (where temperature sensors transmit the temperature of the monitored point along with their own ID, which then automatically displays the temperature of each monitoring point on a calculator) often have various issues. Generally, using traditional temperature measurement techniques for 10kV high-voltage switch temperature measurement does not yield good results. Therefore, researching a new online temperature measurement system is highly necessary.
1.1 Principle
The working principle of the 10kV high-voltage switchgear's online temperature measurement technology is as follows: The collector utilizes an antenna to transmit a wireless electromagnetic wave signal to a SAW (Surface Acoustic Wave) sensor. Upon receiving the battery wave signal, the interdigital transducer (a widely-used effective Rayleigh surface wave transducer) generates surface acoustic waves. These waves then propagate along the surface of the voltage base material to the reflective area and return to the interdigital transducer. The interdigital transducer, using the antenna, emits a reverse electromagnetic wave that the collector receives [1].
1.2 System Composition
1.2.1 Station Control Layer
The station control layer is primarily composed of SCADA (Supervisory Control and Data Acquisition) systems and on-site magnetic flux monitoring, with key functions including real-time monitoring within the station and the application of remote high-voltage switchgear for optimal performance.
1.2.2 Intermediate Layer
The intermediate layer serves as a crucial centralized server for the temperature measurement system. Typically, each station is equipped with a centralized server, which, by utilizing the significance of the RS485 bus, tightly integrates the temperature sensors of various high-voltage switchgears. It also organizes and categorizes all temperature information of the station's switchgears, and provides communication regulations based on the 103/104 standard at the intermediate layer to ensure effective communication between control layers. Furthermore, the centralized server should promptly supply a 24V output power (using a heatsink and a DC-DC converter) to facilitate the long-term normal operation of the sensors.
1.2.3 Process Layer
The process layer is primarily composed of sensors and antennas. Sensors must be capable of installation under high-voltage, temperature-measuring points, such as at junction switches, incoming busbar connection points, and cable outlet connection points.
Feature Analysis of Online Temperature Measurement Technology for 10kV High-Voltage Switchgear
1.3.1 Advantages and Disadvantages of Online Temperature Measurement Technology for 10kV High-Voltage Switchgear
As China's science and technology continues to advance, the 10kV high-voltage transmission system commonly features two types of switchgear: the XGN switchgear and the KYN switchgear. Their components mainly include isolating switches, cable connections, and circuit breakers. However, if switchgear is left unattended for long periods, it can accumulate debris like dust, which is small and unavoidable. This fine dust and debris can directly affect the internal structure of the switchgear, leading to malfunctions. Consequently, cleaning the interior of these electrical devices has become a significant issue. Beyond that, cabinet cleanliness is not the only concern; controlling the humidity inside the switchgear is equally important. Excessive humidity can lead to severe dampness within the cabinet, which can also cause high-voltage switchgear to malfunction. Generally, in XGN switchgear, insulation heat-shrink treatment is required at conductive locations. In simpler terms, the entire critical temperature-measuring section of the XGN switchgear needs to be covered with an insulating layer. Under these conditions, personnel cannot conduct internal temperature measurements outside the switchgear, which hinders the timely understanding of the actual internal conditions. Therefore, to fully utilize the practical application of online temperature measurement technology in harsh environments, it is essential to enhance its anti-interference capability and load-bearing capacity, ensuring the authenticity and integrity of the temperature measurement data.
1.3.2 Key Points for Existing Electrical Components Inside the Switchgear Cabinet
The internal structure of a 10kV high-voltage switchgear is rather complex, necessitating a substantial quantity of electrical components. Each component has its own working principle and precautions. However, operating these electrical devices requires a practical approach, as there are significant differences in the operating conditions and procedures of different electrical equipment. Staff should opt for practical methods to use the high-voltage switchgear rationally. Therefore, to ensure the smooth and normal operation of the corresponding temperature measurement work, certain precautions must be particularly noted during the actual installation. For instance, when installing the switchgear, the electrical components of the switchgear equipment itself should be handled with great care to prevent damage during installation. Only by doing so can it ensure proper operation and maximize its performance. It is only through attention to the smallest details during installation that the high-voltage switchgear can fully utilize its capabilities [2].
Current Analysis of Online Temperature Measurement Technology for 10kV High-Voltage Switchgear
2.1 Infrared Thermometry
Infrared Temperature Measurement Principle: A detailed measurement detection system, it is a typical method among non-contact measurement techniques. Currently, infrared thermometers are quite convenient to use, with most models also featuring additional functions such as autonomous photo-taking and automatic temperature point detection. They are widely applied in modern power industries. However, for 10kV switchgear, the internal components and insulators may obstruct infrared radiation, complicating the temperature measurement process and compromising the accuracy of the results. This, in turn, causes difficulties during calibration and reduces the general applicability of these thermometers, which are only suitable for early 10kV switchgear temperature measurements and cannot be used with the currently more common fully enclosed metal switchgear.
2.2 Fiber Optic Temperature Measurement Method
Fiber Optic Temperature Measurement Principle: After the light source emits light and is amplified, it travels through the fiber to the thermally sensitive material section of the sensor, where each sensor reflects a narrow-spectrum pulse light signal. This temperature measurement technology has been researched and developed in recent years and offers the advantage of close contact with the detection equipment during the temperature measurement process of electrical components within switchgear. With the widespread use of fiber optics, it greatly facilitates the smooth progress of temperature measurement, while also being resistant to the electromagnetic environment around it. Additionally, it can avoid damaging the internal mechanical components of the switchgear, and it features strong radiation, high voltage, and high corrosiveness. Under harsh conditions such as electromagnetic interference, it can continuously and uninterrupted perform temperature measurement, which is a capability not achievable by other temperature measurement technologies. This makes it particularly suitable for temperature measurement in 10kV high-voltage switchgear.
2.3 Non-Contact Infrared Temperature Measurement Method
The principle of wireless temperature measurement involves utilizing its inherent insulating properties and resistance to electromagnetic field interference, installing it on each high-voltage switchgear cabinet to directly display the read data. Wireless temperature measurement is a new type of temperature measurement method. For this method, a decentralized temperature measurement device is already in direct use at each temperature measurement point. However, during the establishment process, the receiving temperature information equipment needs to maintain a certain distance from the switchgear cabinet at the installation location. Wireless technology can be used for communication and interaction, thereby completing the high-voltage separation and insulation work. Nevertheless, wireless temperature measurement technology does have some issues, most notably the stability of the temperature measurement equipment. These devices mostly use current induction power sources, where the energy level can vary with changes in electrical load. If the variation in electrical load is significant, it can drastically alter the energy amplitude, potentially leading to power outages during the operation of the temperature measurement equipment.
3 Ankoray Wireless Temperature Measurement System
3.1 System Structure
The Acrel-2000T Wireless Temperature Monitoring System communicates directly with devices at the bay level via RS485 bus or Ethernet. The system design adheres to international standards such as Modbus-RTU and Modbus-TCP, significantly enhancing its security, reliability, and openness. The system features remote signaling, measurement, control, tuning, setup, event alarms, curve, bar graph, reporting, and user management functions. It can monitor the operational status of wireless temperature measurement system devices, achieve rapid alarm response, and prevent serious failures.
Temperature monitoring suitable for power equipment in enterprises such as power internet of things, steel mills, chemical plants, cement factories, hospitals, airports, power plants, coal mines, and transformer substations.
Temperature Online Monitoring System Schematic Diagram
3.2 System Function
The Acrel-2000T temperature monitoring system is installed in the duty monitoring room, allowing for remote monitoring of the operating temperatures of all switchgear within the system. The system features the following main functions:
- Temperature Display: Shows the real-time values of each temperature sensing point within the power distribution system, and allows for remote data viewing via computer WEB or mobile APP.
- Temperature Trend Curves: View the temperature trend curves for each temperature sensing point.
- Operational Report: Query and print temperature data at various temperature sensing points.
- Real-time Alerting: The system can issue alerts for abnormal temperatures at various temperature sensing points. It features real-time voice alarm capabilities, enabling voice alerts for all events. Alert methods include pop-ups and voice alarms, and can also push alert messages via SMS or APP, promptly reminding on-duty personnel.
- Historical Event Inquiry: Capable of storing and managing records of events such as temperature limits, facilitating users in tracing historical system events and alarms, and enabling query statistics and accident analysis.
4 Closing Remarks
In summary, China's scientific and technological level is gradually on the rise, with technology advancing rapidly and related scientific research becoming increasingly intelligent. The 10kV high-voltage switchgear is widely used in intelligent substations. While innovating and reforming the development of technology, it is crucial to maintain its safety. The use of 10kV high-voltage switchgear not only benefits technological progress but also facilitates everyday life. Therefore, it is necessary to increase resources and manpower in the research of high-voltage switchgear to drive its development towards better and faster advancements.
Reference:
Cai Runqiang. Brief Discussion on Online Temperature Measurement Technology for 10kV High-Voltage Switchgear in Smart Substations
Cheng Yang. Research on Online Monitoring Technology of High-Voltage Switchgear in Intelligent Substations[J]. Automation and Instruments, 2016(9): 108-109.
[3] Ankerui Enterprise Microgrid Design and Application Manual, 2020.06 Edition
[4] Ankorree User's Substation Power Distribution and Monitoring Solution, October 2021
Author Bio:
Li Xuewei, a female employee currently working at Jiangsu Anke Rui Microgrid Research Institute Co., Ltd., specializes in the research and application of energy efficiency management in the power monitoring industry.
Phone: 178-2173-3155 (WeChat number)
