Research And Development On Protection Device Based On DSP For Distributed Power Line

Low voltage distributed power line supplies power to users directly. Its reliability is very important. With the development of power distribution automatization and the improvement of power system integrated automatization, the demand for distributed power line protection and surveillance is becoming more and more strict. This dissertation analyses and compares the microprocessor based protection and measurement algorithms used in power system. And expounds how to realize each protection method by microprocessor. After referencing the developed similar devices, this dissertation puts forward to develop an advanced low voltage distributed power line protection device with TMS320LF2407 DSP. A sample device has been developed. Experiment shows that it achieves the designed technology requests. The main structure of the device, the selection of the microprocessor, the design of analog inputs, and the A/D sampling method are argued in detail in this dissertation. And the selection and design of switch-in module, switch-out module, communication module, clock module, data storage module, keys module and frequency detecting module are also discussed. Lastly, according to the device's technology request the hardware circuit is chosen and the hardware design is finished. The system software uses typical up to down and modular designing methods. In this dissertation, the total frame of main program, the design of A/D sampling interrupt program, the design of CAN communication program and the processing of communication message are explained mainly. After comparing several kinds of data type operating time, the integer and long integer data are used to reduce the data calculating time. So it satisfies the device's real time request quite well. And several problems in software designing and debugging are summarized in this dissertation at last.The device has passed the total experimental validation. Experiment result shows that this device completes the exact current protections, voltage protections and alarms. It realizes the accurate measurement, calculation, storage and display of measuring data. It fulfills the remote surveillance by PC through CAN communication. Experiment result shows that the designed device has achieved anticipative target. And the development of a new, advanced low voltage distributed power line protection device is well completed.