| High voltage switch cabinet is an important control and protection equipment in the power system, also an important part of the smart grid. The paper sets the high voltage switch equipment under the environment of smart grid as the research background, put forward the on-line monitoring system for high voltage switch cabinet with the ARM as the core in view of the current high voltage switch cabinet’s big volume, heavy quality and low degree of automation. In order to change the current high voltage switch cabinet’s condition of low measurement precision and dynamic response and adapt to the demand for the development of high voltage switch cabinet in the smart grid environment, the paper innovative uses a magnetic sensor instead of the traditional current transformer to achieve bus bar current measurement, and set up a multi-channel high-speed synchronous acquisition monitoring system. The main contents of the paper have the following several aspects:(1)In view of the complex environment of high voltage switch cabinet for high voltage, high current and magnetic field, the paper establish the mathematical model and the topology structure of the magnetic sensor for current measurement, and analyze current measurement of magnetic sensor topology model in theory. According to the requirements of dynamic real-time system for intelligent high-voltage switch cabinet, the paper analyze the principle of high-speed data acquisition and the integrity of the sampling clock,obtained the system clock jitter standard is less than 25 ps, and determine the software synchronous sampling way of the system.(2)Using the main control chip ARM9/S3C2440 A and 8-channel high-speed synchronous AD7606 converter for the main components to build the hardware architecture of the system. According to the actual function of monitoring system, the periphery functional modules of the system was extended, mainly including signal conditioning module, the module transfer module and communication module. Eachfunction module are designed integrated and developed PCB of the system, reducing the volume of the monitoring system’s hardware effectively.(3)According to the real-time dynamic monitoring functional requirement of the intelligent high-voltage switch cabinet, the monitoring and control program of the system are developed and designed the modularly. The program mainly include the start convert program of AD, the SPI communication program between AD and the master CPU, the data acquisition, calculating and status control program and the real-time communication program with PC.(4)Experiments have been carried out to measure the performance of magnetic sensor and test the machine characteristics of the system. The measurement characteristics of the magnetic sensor are verified and the topology structure is optimized through a lot of experimental analysis. It is obtained that relatively 13 cm is the best place to set the sensor,the corresponding measurement characteristics of magnetic sensor is the linear range of 0 ~1300A, and the repeat-ability error of measurement is less than 0.5%. Through comparing the collected voltage and current parameters of the system with the standard parameters given out by the grid simulator, the paper get the relative error of voltage and current measurement of the system.Through the operation of the system debugging, the running feasibility of the designed monitoring system is proved under the actual working condition in high voltage switch cabinet. The current measurement range of the monitoring system is 0~1300A, the voltage measurement relative error is less than 0.58%,the current measurement relative error is less than 1.8%. The accuracy of the system reaches the designed standard accuracy of 0.5. The sampling rate of the electric parameter acquisition channel is up to 200 KSPS,realizing the dynamic real-time monitoring of the system effectively, and meeting the application requirements of high voltage switch cabinet in the smart grid environment. |
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