基于Crowbar电路的双馈机低电压穿越特性仿真分析

双馈感应发电机特殊的电路结构使其在并网运行时对电网电压跌落非常敏感,通过Crowbar保护电路短接转子是目前常采用的实现双馈感应发电机低电压穿越的措施,其主要缺点是此时双馈机运行于异步机状态,需要从系统吸收无功进行励磁。本文对双馈感应发电机电压跌落下的运行特性进行了分析,在总结了传统的Crowbar投切控制策略优缺点的基础上提出了一种改进的Crowbar投切控制策略。在M ATLAB/Simulink仿真平台下搭建并网双馈机风电场模型,对双馈机低电压穿越运行特性和所提的Crowbar投切控制策略进行仿真分析。仿真结果证明了所提的改进的Crowbar投切控制策略的有效性。

Simulation Analysis of Low Voltage Traversal Characteristic on Crowbar-based Doubly-fed Generator

Due to its special circuit structure,the doubly-fed induction generator is very sensitive to voltage drop when connected in the grid.A common measure to ensure the traversal of doubly-fed induction generator at low voltage is to protect the circuit short-connected rotor through Crowbar,but the disadvantage of this measure lies in the fact that the doubly-fed generator operates in an asynchronous state and it has to draw on reactive power from the system to realize excitation.This paper first analyses the operation characteristic of the doubly-fed induction generator during the voltage drop.Then based on a summary of the traditional input and elimination control through Crowbar,it puts forward an improved input and elimination control.On MATLAB/Simulink platform a grid-connected doubly-fed wind farm model is put up where the improved input and elimination control is adopted and the traversal operation characteristic of the doubly-fed generator at low voltage is studied.The simulation analysis proves the effectiveness of the improved input and elimination control.