468 / 2017-05-08 14:05:04

A New Method for Measuring the Speed Characteristics of High Voltage Circuit Breaker Based on Machine Vision Algorithm

14075,13895,13894,13892,13166

The speed characteristics of moving contact is vital to the high voltage circuit breakers which play important roles in electric power system and whose running states affect the safe operation of power system directly. Thus, it is of great significance to measure the speed characteristics of moving contact accurately for the performance analysis and state evaluation of high voltage circuit breakers. Due to the contacts of high voltage circuit breaker are completely isolated by arc control device, the common direct measurement methods have some disadvantages. Firstly, it is always difficult to mount a displacement transducer or angle sensor into a high voltage circuit breaker online. And then, the sensors and its attachments always take negative impact on the mechanical characteristics of circuit breaker itself. Besides, it would be a time-consuming task if a large quantity of experiments should be carried out with different high voltage circuit breakers. Aiming at solving those problems, this paper developed a method for measuring the speed characteristics of high voltage circuit breaker based on machine vision algorithm. This non-invasive method just needs to draw or mount some colorful markers on the surface of the moving parts as the movement reference points whose moving trail is in direct proportion to the moving contacts of the high voltage circuit breaker. Then the moving tracks of these reference points will be recorded by high speed camera and identified by the machine vision algorithm automatically after processing the videos. The displacement curve of moving contact can be obtained finally, so as the speed characteristics. The Fig. 1 shows the schematic diagram of the whole measuring system. It mainly contains the high-speed camera, the computer, and the moving parts of the circuit breaker. In the measuring process, the first step is the data acquisition procedure, in which, the marks are set and their movements are recorded by high speed camera. The second step is the main part of the system. Through utilizing the technic of color discrimination which is implemented with machine vision algorithm, the relative coordinates of every mark in every picture can be calculated. Finally, the speed characteristics of moving contact can be calculated using these coordinates. The experiments have been carried out with a 252kV SF6 circuit breaker. The markers were made on the surface of rotation shaft and contact connecting rod. The movements of the markers on rotation shaft are curve and proportional to the linear movement of the moving contact. As showed in Fig. 2, the experiment result presents that the characteristics measured by the method proposed in this paper is precisely compared with other displacement sensor, and meets the requirement of speed characteristics detection. This method doesn’t require any additional fixtures and is more convenient than traditional measuring method. Furthermore, it’s of high efficiency without the necessity for taking the high voltage isolation into account at the same time.