By Nidhi DhullReviewed by Susha Cheriyedath, M.Sc.Apr 16 2024A recent article published in the journal Scientific Reports demonstrates the design and development of a robotic arm for rinsing porcelain bushing in high-voltage substations. Researchers used artificial intelligence and 5G technology to create a prototype with an integrated control system. The robotic arm's feasibility and effectiveness were successfully tested in the Nanjing power grid.
Study: Robotic Arm for Porcelain Bushing Cleaning in High-Voltage Substations. Image Credit: Somsit/Shutterstock.com
Conventional Porcelain Bushing Cleaning
Porcelain bushings are critical insulators used extensively in electrical substations for external insulation. When these bushings become contaminated with pollutants, they pose significant risks to associated electrical devices, potentially causing flashovers, widespread power failures, or even casualties. Therefore, regular cleaning of porcelain bushings is essential to ensure the safe and efficient operation of substations.
Conventional cleaning of porcelain bushings typically involves manual methods, either with a power shutdown using water or air blowing while the power is on. Maintenance workers perform this cleaning by climbing onto the electrical device or standing on a platform, using special cleaning cloths or brushes. These manual methods are not only inefficient but also pose significant safety risks. In contrast, automated cleaning devices, such as robots, offer a safer and more effective solution. These devices improve cleaning efficiency and consistency while eliminating the risks associated with human involvement.
Design of Robotic Arm
In this study, researchers developed an automatic cleaning robot designed for the maintenance of 500 kV porcelain sleeves in substations during power outages. The robot features several key components: a mobile electric lifting platform that supports the entire device, a cleaning brush finger, an operational box, a drive control box, photoelectric switches, and a lead screw module for precise positioning. The operational box is equipped with a control button box and an industrial control touch screen, which are used to manage the platform’s movement and the cleaning brush’s speed.
The cleaning brush finger is made of aluminum alloy and features a 120-degree split structure, enabling it to easily adapt to the complex environments of substations. It is powered by DC brushless motors, which allow for speed adjustments based on the specific conditions of the site. Moreover, the cleaning brush rod is designed to have a variable axis length, which ensures efficiency and consistency in cleaning porcelain bushing.
Photoelectric switches are integral to the robotic arm, aiding in the precise localization of its movements and in detecting the position of the porcelain bushing. The positioning module ensures that the bushing is perfectly centered within the cleaning brush finger's opening ring, which minimizes the risk of collisions caused by positional deviations. Additionally, the device features an open-cleaning circular ring structure that simplifies and enhances the alignment of the porcelain bushing during the cleaning process.
Control Method and Edge Computing
An efficient control system was vital for the functionality of the robotic arm. In this design, researchers employed an S7-200 programmable logic controller (PLC) as the central control unit. This PLC processed sensor signals to manage every movement of the cleaning robotic arm. The system utilized a real-time angle-feedback control method to automatically level the platform, ensuring that the cleaning brush finger avoided collisions with the porcelain sleeve during balance adjustments. Additionally, data from speed and torque sensors were collected by an intelligent maintenance terminal and relayed back to the monitoring system via a 5G network.
After positioning the robotic arm, it was crucial to maintain it at a safe distance from the electrical devices in the substation during the cleaning process. To achieve this, the researchers employed edge computing in conjunction with ultra-wideband technology to develop methods for safe-distance control and precise localization. By integrating the Internet of Things (IoT) with edge computing, the working area of the arm could be defined on a granular level. This integration ensured that the charged areas near the worksite were isolated, safeguarding both the equipment and personnel during the cleaning of the insulator.
Field Test
To demonstrate the practical application of the proposed automatic insulator cleaning system, a prototype robotic arm was developed based on the porcelain structure of a typical 220 kV circuit breaker in a 500 kV substation. After initial commissioning in the laboratory, this prototype was used for a cleaning test on the Nanjing power grid, where its performance was thoroughly evaluated.
The platform's balancing adjustments, based on the established control strategy, were completed in just 0.5 seconds. Once the robotic arm reached its designated position, cleaning commenced automatically. A 4.8-meter-long 500 kV porcelain bushing was cleaned in 30 seconds, with the total cleaning time—from initial positioning to completion—ranging between 50 and 105 seconds. This demonstrates a significant efficiency improvement over traditional manual cleaning methods, confirming that the robotic arm successfully passed the field test.
Significance of the Work
The robotic arm developed in this study efficiently rinses porcelain bushings and transmits all corresponding information using 5G technology for feedback. Its effectiveness, quality, and safety were verified during the field test at the Nanjing power grid, where it not only met the main performance goals but also exceeded design expectations.
In conclusion, the intelligent porcelain bushing cleaning robotic arm devised in this research can effectively maintain electrical devices in high-voltage substations and serve as a preventive measure against pollution flashover of porcelain bushings. This study broadens the application of robots in cleaning insulators and enhances the level of state control over substation equipment.
Journal Reference
Chen, H., Han, W., Xu, W., Tang, Z., Chen, Y., Xu, P., & Ma, Z. (2024). Design of robotic arm for the porcelain bushing in substation. Scientific Reports, 14(1). https://doi.org/10.1038/s41598-024-58443-7, https://www.nature.com/articles/s41598-024-58443-7
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