No abstract

Aiming at the problem of off‐line deicing in overhead transmission lines, such as poor continuity of power supply and possible damage of lines caused by over‐thick deicing, a new online anti‐icing and deicing method based on external excitation resonance is proposed. The theoretical basis of the external excitation resonance to anti‐icing and deicing is established. Then the modal characteristics of the external excitation resonance are determined through the modal analysis of the ice‐coated transmission lines, and the reasonable frequency range of the external excitation resonance is obtained. According to the theoretical analysis and calculation results, the anti‐icing and deicing robot system is designed by the external excitation resonance. Intelligent video technology is used to detect the icing condition of transmission lines in real time, and the vibration frequency range of transmission lines is analyzed and calculated. The vibration frequency is adjusted through the real‐time tracking of the resonance feedback mechanism to ensure the continuity of the resonance working state, so as to effectively realize the efficient anti‐icing and deicing of the transmission lines with the thickness of 1–3 mm at the initial icing stage. Finally, the parameters of the key components of the system are calculated and determined, and the related influencing factors are analyzed. A new deicing theory based on anti‐icing theory is proposed, and specific engineering measures are given. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

No abstract

Traveling wave reflection method is widely used in cable length measurement and fault location. How to effectively remove noise interference and accurately identify the starting point of pulse reflection is the key problem to be solved by this method. In this paper, two new methods, the improved weighted coefficient method based on the wavelet theory and the curve fitting method, are proposed for different identification accuracy and velocity by analyzing the measured reflected wave signal. The improved weighted coefficient method was used to process the traditional denoising threshold with the same value of ±thr, and then the calculated weighted threshold was used to reduce the noise of the measured signal, so as to highlight and identify the starting point of reflection pulse. The curve fitting method is adopted to compare the reflected wave anomaly with the threshold value of the corresponding length cable. If the threshold value is exceeded, the fault reflection can be judged as fault reflection. Then the quadratic function fitting is carried out here, and the starting point of the reflected pulse is directly determined by using the intersection point of the quadratic curve and the reference voltage. The experimental and simulation results show that the improved weighted coefficient method solves the problems of unsmoothness of denoising and discontinuity of derivative of denoising function, improves the accuracy of identifying the starting point of reflection wave, provides a new algorithm for improving the measurement accuracy. The curve fitting method has high speed, low demand for hardware, and the error can be controlled within 10ns, which is more suitable for low-cost equipment based on Microcontrollers.