基于转速控制的双馈风电机组机侧变流器IGBT器件结温波动抑制策略

Insulated Gate Bipolar Transistor Junction Temperature Fluctuation Depression Strategy of Doubly Fed Wind Power Converter Based on Rotor Speed Control

针对当前双馈风电机组机侧变流器在同步转速点附近结温波动大、影响器件运行可靠性的问题,提出一种基于机组转速控制的绝缘栅双极型晶体管(IGBT)结温波动抑制策略。首先,基于最大功率点跟踪(MPPT)控制原理,并结合变流器IGBT模块等效热网络,建立双馈风电变流器结温计算模型。其次,针对机侧变流器在同步转速点附近结温波动出现的"尖峰"现象,从减少机组低频运行范围和提升同步转速附近区域穿越速度的思路出发,提出基于功率、转速双控制外环的改进最大功率点跟踪控制策略。最后,搭建基于PLECS和Simulink联合平台的双馈风力发电系统仿真模型,对机组在亚同步和超同步转速间动态往返变化的变流器电-热性能及其在同步转速附近区域的稳态结温进行仿真,并开展变流器结温抑制效果验证的等效实验。仿真和实验结果验证了所提改进控制策略对抑制机组同步转速点附近变流器IGBT结温波动的有效性。

As with the rotor side converter of doubly fed induction generator （DFIG）, considering the problem of large junction temperature fluctuation of IGBT may greatly reduce its reliability under synchronous operation. A control strategy based on the rotor speed control of DFIG was proposed to depress the insulated gate bipolar transistor （IGBT） junction temperature fluctuation. First, a junction temperature calculation model of wind power converter was established, based on the principle of maximum power point tracking （MPPT） control strategy, and combined the DFIG simulation model with the equivalent thermal network of IGBT module. Then, an improved MPPT control strategy with a new power-speed outer control loop of doubly fed induction generator was proposed to solve the problem of large junction temperature fluctuation under synchronous operation condition. Herein, the idea of reducing low frequency operation range of rotor side converter and improving the variation gradient of speed at the operation range near synchronous speed was adopted. Finally, simulation models of a doubly fed wind power generation system were established by combining PLECS and Simulink platform. The electric and thermal performance of rotor side converter were performed under different speed variations between sub-synchronous speed and super-synchronous speed of DFIG. The steady state junction temperature was further analyzed around synchronous speed operation state. Furthermore, an equivalent experiment was established to testify the validity of the junction temperature depression. Simulation and experimental results show that the proposed control strategy can effectively depress the IGBT junction temperature fluctuation of the rotor side converter under synchronous operation condition of DFIG.