Route Planning of Unmanned Aerial Vehicle Patrol Inspection for 500 kV Converter Transformer
Pu Ziheng1,2, Zhang Long1,2, Yu Xinyun1,2, Chen Jianbao3, Wan Quan3
1. Hubei Provincial Engineering Technology Research Center for Power Transmission Line China Three Gorges University Yichang 443002 China; 2. College of Electrical Engineering & New Energy China Three Gorges University Yichang 443002 China; 3. State Grid Hubei DC Transport and Inspection Company Yichang 443002 China
Abstract：Converter transformers are important equipment in DC systems, and they need to be regularly inspected. However, due to the large volume of converter transformers, there are blind spots in both manual inspections and fixed camera inspections. Unmanned aerial vehicle (UAV) can conduct aerial patrols with high operability and flexibility, which can effectively compensate for the shortcomings of manual patrols, solve the blind spots of high-level equipment patrols, and significantly improve the quality and efficiency of patrols. However, the complex electromagnetic environment in the converter transformer area may cause UAV to be interfered and lose control, and a safe inspection path needs to be planned. Firstly, a three-dimensional simulation model is established based on the actual layout and equipment size of the converter transformer square area of a 500 kV converter station. The spatial electromagnetic field distribution in the converter transformer square area under actual operating conditions is calculated using the finite element method. Then, based on the results of the magnetic field withstand test of the UAV and scholars' research on the ability of the UAV to resist electromagnetic interference, it was determined that it was very safe to fly within an electric field strength of 50 kV/m and a magnetic induction strength of 100 µT. Therefore, based on this safety threshold, the safe flight area range of the UAV is determined, and the inspection path of the UAV is planned in combination with the blind area of the converter transformer and the parts that need to be inspected. The planned path is as follows: The drone takes off from outside the isolation wall, enters the transformer inspection area in a small field strength area close to the valve hall side, descends to the inspection height, and then successively performs inspection on the large oil conservator, high voltage bushing, small oil conservator, pressure relief valve, and online oil filter. Finally, the electromagnetic field intensity on the planned UAV inspection path was calculated, and after verifying the safety of the inspection path, the actual flight inspection test of the converter transformer was carried out. Through the above research and analysis, the following conclusions can be drawn: (1) The strong electromagnetic field region of the converter transformer is mainly distributed near the high-voltage bushing and high-voltage bus, and the electromagnetic field intensity near the insulator string is relatively low. The minimum safety distance between the UAV and the high-voltage bushing and busbar is 700 mm and 1 500 mm, respectively. (2) The maximum electric field intensity on the planned path is 27 kV/m, and the maximum magnetic flux density on the path is 60 µT. When considering the path offset of 500 mm, the maximum electric field intensity is 31.73 kV/m, and the maximum magnetic flux density is 72.72 µT, both of which are smaller than the electromagnetic field safety threshold that the UAV can withstand. (3) According to the planned inspection path, field tests were conducted and it was found that the drone could complete the inspection work safely and reliably according to the inspection path, with little impact of electromagnetic interference on it, and good shooting results, which well verified the feasibility and rationality of the path.
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2023, Vol. 38 
