Research On DSP-Based Automatic Excitation Controllers

The excitation controller is a significant part of excitation systems,which is important to keep security and stability of power systems. The nuclear processor of a digital excitation controller tends to compound the functions of several CPU into one powerful CPU, in home and abroad. It is favor to decrease work on system maintenance and improve system reliability. Improvement in automation of electric power systems sets an even higher requirement for the computation of the digital excitation controller. Emergence of new DSP for demanding control applications supplies well software and hardware bed to reach the goal and meet the requirement referred above.Firstly, functions and development of excitation control systems are introduced, consist of the excitation control mode, excitation control theory and hardware development process and tendency. Then, this paper introduces the feature, selection and design environment of DSP. Finally, the great mass of this article is focused on research of main idea, hardware and software design of function modules for a DSP-based excitation controller. Something of this research is interesting in three respects. The new excitation controller design uses an advanced DSP, TMS320F2812, as a center processor. In this way, the main function modules of the excitation controller can be compounded into a compact unit, which is more favorable to decrease disturbance between each other, reduce the volume, improve the efficiency and reliability of excitation controllers than other designs based on Single-chip Microcomputer or Industry Control Computer. In order to solve the problem of multi-channel synchronized AC sampling, a scheme consists of a 16-bit, 6-channel, parallel AD convert cooperating with a PLL circuit is presented, which can make the calculated value of power and power factor more close to its real. In the module of phase-shift trigger pulse generation, a new technology of rapid pulse train triggering is used to improve the trigger pulse gradient and reduce the requirement of pulse transformers.The DSP-based excitation controller is designed to be expandable, hardware of master control unit is extended to be compatible to different voltage level, and software of the controller are programmed in module design method. The result of the laboratory test shows that the design of hardware and software could cooperate well, and the predictive design objects are attained essentially.