Research On The Electric Control System For Large-Scale Wind Turbine Generator

The utilization of wind energy which is clean has become more and more important in electric power, In this paper, the electric control system of the large-scale Wind Turbine Generator(WTG) is designed and studied, including central control system and grid-connected control system.Firstly, according to the requirements of the electric control system, the input and output signals of the central control system are analyzed. And the configuration of the core is based on the Siemens S7-300. On the basis of the idea of modularized software design, the flowcharts and the corresponding safety and protection design are given.Secondly, this paper discusses the technique of soft starting and soft cutting-in electrical network for asynchronous generator. Mathematic model of WTG has been established which includes wind turbine, induction generator, thyristors, synchronous 6-pulse generator and so on. The numerical simulation curves on the 275kVA WTG are given. With the model, direct starting, increasing voltage starting and current limit starting are studied and compared. The results of simulation suggest that current limit starting has good performance in starting current and torque limit and their oscillation restraint. Through simulation, it can be pointed out that the generator can be connected to electric grid stably when the current limit control method is used. The thesis also discusses the switch process between the big and small generators for WTG.The hardware and software of the grid-connected control system are designed. The function modules of the system with TMS320F240 as its central unit are illuminated. The flowcharts of the program and the subprograms by means of current limit starting are all given.Finally, the validity of the theoretical analysis and computer simulation is proved by experimental results. And the results show that the electric control system can satisfy the requirement of large-scale WTG...