Research And Implementation Of Gas Relay Calibration System Based On AVR

Large oil-immersed power transformer is one of the main structure, which is directly related to the reliability of safe operation of the grid. And the gas relay is one of the indispensable main protection device which is essential to monitor internal fault, one moment it reflects the transformer internal fault, enabling rapid removal of faulty equipment, to ensure grid security.However, gas relay runs in high temperature, high vibration and high magnetic fields. A long period running, which is easy to create the conditions decline, the action value offset setting value; and the accumulation of water droplets in the junction box, making the gas relay malfunction. Therefore, in accordance with the " DL/T 540-1994 inspection regulation of the QJ-25/50/80 type gas relay " the gas relay, must to be periodically tested.At present, the domestic gas relay detection device has many shortcomings, sush as outdated measuring methods, small measuring range, complicated operation, standards traceable difficulties and can only detect a single diameter of the gas relay, and it's hard to demolish, and not easy to remove to inspection, so it brings problems to the inspection of the gas relay.In order to solve the above problems, based on the analysis of domestic and foreign research, paper proposed two detection system implementations - indirect flow velocity calibration method and direct flow velocity pulse method. According to the above two methods, the overall design scheme of the system achieved, and we study the feasibility of the system overall implementation scheme with AVR micro-processor, and based on all above, we achieved hardware and software design which is all the system modules that need to implement the functions. And we focused on micro-control unit and its' peripheral function circuit developement and simulation which is based on AVR micro-processor.The repetitive and comparing experiment shows that the system can meet the inspection regulation's requirements and calibrates all kinds of gas relay. Meanwhile indirect flow velocity calibration measurement is more suitable for on-site spot check, to facilitate the adjustment of flow velocity values; And direct flow velocity pulse measurement is more suitable for accurate measurement and periodic comparison. The device is convenient, fast, flexible and has good repeatability, high accuracy characteristics, and it can without removing standard flowmeter, and using velocity correction apparatus to revise velocity values of the standard, it both saved the inspection cost, reduce labor intensity, and also to improve the work efficiency, and has very good practical value and application prospect.