Automatic Identification Method Of The Point Instruments In The Transformer Substation

Pointer instrument has the advantages of simple structure, easy to use and maintenance, high reliability, low price, waterproof, antifreeze and dustproof, so it is widely used in the electric power industry and chemical industry. The transformer substation of power system has many kinds of pointers instruments, such as the barometer, the thermometer, the oil temperature table, the hydraulic table, the lightning arrester table, etc. Current measurements is always with the help of close eye observation, it is low accurate and low reliable; And the pointer instruments in the transformer substation generally do not have cable interface function, when the system is going to perform some special tasks, such as relay protection which need to monitor the current meter, voltage meter and thermometer readings which can’t be real-time reflected in the computer and real-time monitoring recording and analysis, it is hard to report to the observer the equipment malfunction and the unsafe conditions immediately. And it need record a large amount of data by manual every day, it is easy to cause visual fatigue. Manual operation is not only accuracy, but also has the characteristics of low efficiency, poor reliability and poor repeatability, and the intensity of labor is big, meanwhile it is easily influenced by outside factors.In view of the pointer instrument of automatic identification in the smart substation, this paper proposes a new method which is more accurate based on the traditional distance method, ensuring the precision of distance method. In this paper,the first step is enlarging or reducing the image to meet the requirement of the processing.The image preprocessing is conducted, including the use of median filtering method for image noise, filtering; Then using the projection method for skew detection and correction; In order to meet the requirements of the image, Hough transform method is used to extract the further information of the dial pointer and the calibration tails. Then changing the area of the calibration from fan-shaped to rectangle. Identify the numbers of the calibration tails and calibrating the scale line with the numbers. The distance relations between the dial pointer and the calibration tails are used to get the pointer readings, the error analysis and the results are conducted in the follows.The experimental results shows that: this method is very effective for the pointer instrument in the intelligent substations, and has higher precision and practicability,which can meet the recognition requirements of the pointer instrument in the intelligent substation, having a certain development prospects.