Anke Electrical Co., Ltd.

SummaryThis article addresses the engineering application needs of enclosed 10kV high-voltage switchgear in power grid systems, proposing a new passive wireless temperature sensing method and monitoring technology for the wireless temperature measurement of switchgears. The end of the article illustrates the installation process and application effects of the monitoring system through a grid-connected test case of a substation. The application of this system can effectively enhance the automation level of equipment inspections for power grid operation departments, strengthen the safety control of power grid equipment, and possesses broad prospects for engineering applications.

Keywords:Wireless Temperature Measurement; Online Monitoring; Switchgear; Sensor Technology

I. Introduction

Currently, full automation for monitoring the temperature of critical parts in substation equipment is not achievable. Some temperature monitoring devices are quite outdated, while others are customized, limiting their applications. Moreover, there is no unified standard for temperature measurement devices, leading to limited versatility and a high difficulty in replacing electrical components. Therefore, to realize real-time temperature monitoring, it is necessary to analyze the temperature monitoring needs of key parts in the substation, in conjunction with the company's existing power station equipment, and develop a system that meets the full automation requirements for substation temperature monitoring.

Section II: Online Temperature Measurement Technology Analysis for Enclosed High-Voltage Switchgear

Substation equipment temperature monitoring refers to the real-time monitoring of critical components in substation equipment through temperature monitoring devices, to understand the temperature changes of the equipment and to perform real-time early warning work, thereby reducing the occurrence of operation accidents in high-voltage switch cabinets. Therefore, real-time online temperature measurement has the following two functions: one is to monitor temperatures in real-time, understand the equipment's operating status, and prepare for emergency response to minimize accidents; the other is to achieve 24/7 unmanned real-time monitoring, reducing labor costs and lowering operational expenses. High-voltage switch cabinets have certain advancement in temperature measurement technology and are operationally safe and reliable. The device needs to run stably within the switch cabinet for a long time, and both the system and the device must meet compatibility and cost-effectiveness requirements for future system expansion. The requirements for these aspects necessitate an analysis of the temperature measurement environment and a comparative analysis of temperature measurement methods to find the most suitable method for the on-site environment.

III. Framework Analysis of 10kV Switchgear Passive Wireless Temperature Measurement System

The proposed system utilizes a multi-substation solution for application. The high-voltage equipment passive wireless temperature real-time monitoring and early warning system is primarily composed of collection devices and software systems, featuring a tree-like network architecture. The high-voltage rooms of the various sub-stations form the first layer, where passive wireless temperature sensor collection devices are installed inside each enclosed switchgear cabinet. These devices mainly include 6 passive wireless temperature sensors (temperature detection devices) and 1 wireless temperature measurement terminal (terminal equipment). The 6 sensors are installed at locations prone to heating, such as outgoing line joints,梅花 touch points, incoming line joints, etc., while the terminal is installed in the low-voltage room within the switchgear cabinet. The sub-stations represent the second layer, with each sub-station equipped with 1 wireless temperature measurement front-end unit to collect data from various collection terminal devices and package it for transmission to the inspection center via IP networks. The inspection center constitutes the third layer, requiring each center to be equipped with 1 monitoring server for displaying and processing temperature data of high-voltage equipment within the sub-stations. If necessary, the inspection centers can also send temperature signals to the main server of the power company. The system's main server, as the fourth layer, provides accurate temperature information for back-end service personnel, facilitating timely arrangements and handling.

Armored switchgear electrical equipment passive wireless temperature measurement system mainly achieves real-time temperature monitoring, capable of dual settings for early warning and alarm to prevent problems before they occur. It operates simply and rationally, with rich and comprehensive data display. The following features are mainly through third-party

To achieve the fourth layer:

The system can continuously monitor the temperature changes in high-voltage switchgear and promptly make defect judgments.

(2) Historical temperature values of electrical equipment can be saved for later comparison and assessment.

(3) The system allows for statistical analysis of temperature data and the creation of charts for easy viewing.

(4) High-temperature alerts and monitoring prevention can be set for temperature values.

Four: Applications of Passive Wireless Temperature Monitoring

1. Overall engineering application approach

The wireless temperature monitoring system designed in this article directly utilizes temperature sensors to collect temperature data from key equipment and transmits it wirelessly to the core components of the system. After collecting the temperatures of these core components, the system's algorithm performs statistical analysis on the temperature data, enabling real-time alarm functions based on pre-set temperature settings for each component. The system then relays the derived conclusions to the equipment maintenance department, which conducts comprehensive analysis based on the transmitted results and establishes equipment maintenance and management measures to reduce the frequency and duration of equipment failures, thereby enhancing the efficiency of power distribution operations.

2. Preliminary engineering installation

The substation is equipped with a total of 8 switch cabinets. The wireless temperature monitoring system designed for this project consists of two parts: one is the sensors, with each switch cabinet featuring 12 temperature monitoring points, totaling 96 temperature sensors. The other part is the data networking, including 16 temperature monitoring devices and 2 monitoring hosts. The preliminary construction process is divided into 7 steps, as shown in Table 2. From the pre-construction meeting to the preliminary preparations, installation, debugging, testing, and finally the acceptance inspection, there are clear construction standards in place to ensure the successful installation of the passive wireless temperature detection system.

Table 2: Construction Process

V. Profitability Analysis

The introduction of the passive wireless temperature measurement system allows for continuous 7*24h real-time monitoring of switchgear temperatures, promptly sending accurate monitoring data to prevent power grid failures caused by excessive electrical equipment temperatures. Additionally, the system offers real-time alarm functionality, enabling preemptive measures to avoid unforeseen losses.

(2) The adoption of the passive wireless temperature measurement system has transformed the previous "passive maintenance" into "active maintenance." It provides pre-emptive data preparation for condition-based maintenance, continuously enhancing the safety and reliability of power grid operations. Currently, the power supply companies have implemented online temperature monitoring for switchgear in some sub-stations, offering scientific data support and basis for condition-based maintenance. The deployment of this system also improves inspection efficiency, reduces the workload of maintenance personnel, and enhances the efficiency of power supply operations.

(3) Once the system is operational, it eliminates the need for scheduled on-site maintenance by technicians and allows for real-time monitoring of equipment temperatures. Immediate alerts are triggered upon detecting temperature fluctuations, reducing the frequency and duration of equipment failures, improving power supply quality, and generating greater economic benefits for power companies. By assuming a reduction of one power outage maintenance event per year, with an 8-hour maintenance duration, and an average load current of 300A per outstation (approximately 5MW), this project's eight intervals can provide an additional 320MWh of electricity annually. At a value of 0.6 yuan per kWh, this would result in an extra profit of approximately 192,000 yuan for the company. The calculated figure only represents the economic benefits of the system. In practical production and daily life, the system also reduces power outages, enhances power supply quality, and helps the power supplier earn a favorable reputation and increased profits.

Section 6: AnkoRe Online Temperature Monitoring System Solution

1. Overview

The online temperature monitoring device for electrical contact points is suitable for the temperature monitoring of equipment such as cable joints, circuit breaker contacts, knife switches, high-voltage cable midpoints, dry transformers, and low-voltage high-current devices within high and low-voltage switchgear cabinets. It prevents potential safety hazards caused by overheating due to oxidation, loosening, and dust, which can lead to excessive contact resistance. This enhances equipment safety, ensures timely, continuous, and accurate reflection of the equipment's operating status, and reduces the rate of equipment accidents.

The Acrel-2000T Wireless Temperature Monitoring System communicates directly with equipment at the bay level via RS 485 bus or Ethernet. The system design adheres to international standards such as Modbus-RTU and Modbus-TCP for transmission protocols, significantly enhancing security, reliability, and openness. The system features remote signaling, measurement, control, adjustment, setup, event alarms, graphs, bar charts, reports, and user management functions. It can monitor the operational status of wireless temperature measurement system equipment, achieve rapid alarm response, and prevent severe faults from occurring.

2. Application Sites

Temperature monitoring suitable for power equipment in various industrial and mining enterprises such as ubiquitous power IoT, steel mills, chemical plants, cement factories, data centers, hospitals, airports, power plants, coal mines, and substation transformer stations.

3. System Structure

Temperature Online Monitoring System Schematic Diagram

4. System Features

The Acrel-2000T temperature monitoring system main unit is installed in the on-duty monitoring room and can remotely monitor the operating temperatures of all switchgear within the system. The system boasts the following key functions:

1. 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 Curve: View the temperature trend curve for each temperature sensing point.

Operational Report: Query and print temperature data at specified time for designated temperature points.

Real-time Alerts: The system can issue alerts for abnormal temperatures at various temperature measurement points. It features real-time voice alarm capabilities, enabling voice alerts for all events, with alert methods including pop-up windows and voice alarms. Additionally, it can send alert messages via SMS or APP push notifications to promptly remind on-duty staff.

Historical Event Inquiry: Stores and manages records of events such as temperature limits, facilitating users to trace historical system events and alarms, and enabling query statistics and accident analysis.

5. System Hardware Configuration

The online temperature monitoring system is primarily composed of temperature sensors and temperature collection/display units at the equipment layer, edge computing gateways at the communication layer, and the temperature measurement system host at the station control layer, enabling real-time monitoring of the temperature at critical electrical components of the power distribution and transformation system.

Seven, Conclusion

This article analyzes the current state of our electrical equipment and evaluates the adoption of a passive wireless online monitoring system from several perspectives, including sensor technology for switchgear temperature measurement, power supply technology, and communication technology. It primarily focuses on the internal structure of switchgear, compares different temperature measurement methods, formulates a suitable approach for high-voltage switchgear, and conducts on-site installation and testing, with positive results. The article also analyzes the current level of promotion, concluding that the system's safe operation can bring about economic and social benefits.

Reference:

Fei Yijia, Zhang Zhizhong. Application Research on Online Temperature Measurement System for Electrical Equipment in 10kV High-Voltage Switchgear[J]. Modern Information Technology, 2019, 003(015): 179-182.

[2] Xu Yingmin. Research on Online Temperature Measurement Technology of 10kV High-Voltage Switchgear in Intelligent Substations [J]. Electromechanical Information, 2013(9):2.

Ankorri Corporation Microgrid Design and Application Manual, 2022 May Edition