Research Of Indirect Power Control Strategy Of Brushless Doubly-Fed Machine

The brushless doubly-fed machine is no need for carbon brush and slip ring, and has the advantages such as simple structure, high reliability, small capacity required for inverter. Therefore it is particularly suitable for using as a wind generator, and has the perspective applications in VSCF wind power generation field. In recent years, brushless doubly-fed machine has become a research hotspot for the foreign and domestic scholars. Scholars have conducted in-depth research from the mathematical model, structure design and control system. This paper focuses on the indirect power control strategy of brushless doubly-fed machine, the research content completed is as follows:1. The mathematical models of brushless doubly-fed machine are deeply studied and deduced in detail, including the multi-loop model, the d-q rotor speed model, the power winding static coordinate model and the control winding static coordinate model. It laid the foundation for the subsequent research in control system simulation and experiment.2. This paper studies the characteristics of brushless doubly-fed generator, including the no-load characteristic, the power-angle characteristic and the V curve. In domestic and literature, most study of power angle characteristics of BDFM just get some qualitative conclusions from physical concepts. This paper based on the power-angle characteristics expression of the brushless doubly-fed machine which deduced by our research group, this paper preliminarily verifies the correctness of the expression by experiment. This provides reference for the research of brushless doubly-fed generator fault, abnormal and instability condition.3. This paper realizes a dynamic frequency measure method based on software phase-locked loop in assembly language on TMS320LF2407A, and applies to the indirect power control strategy. There is no need for extra hardware integrated circuit in the novel method and the measuring speed is fast. The experiments show that the method is feasible. By using this method, it solves the problems that the control winding flux static angle calculating is not very accuracy.4. Based on the research achievements of our research group, this paper improve the experimental platform of brushless doubly fed machine indirect power control system. Program the software in assembly language based on TMS320LF2407A, improve the indirect power control system and make the experiment performance better. This paper realizes the variable speed constant frequency generation, the active power regulation and the reactive power regulation. The dynamic and static performance in different operating conditions such as super-synchronous and sub-synchronous show the feasibility of indirect power control strategy.