变速恒频双馈风力发电机并网积分型变结构控制

Cutting-in control of variable-speed constant-frequency double-fed wind-power generator with integral variable structure control

为了实现变速恒频双馈风力发电机平滑的接入电网,将积分型变结构控制(IVSC)与磁场定向矢量控制相结合,提出了一种空载并网控制策略。控制系统包括两个采用IVSC的电流控制器和一个基于变速积分的电压偏差控制器,以增加系统在全局范围内对各种扰动的强鲁棒性和动态性能。由于IVSC控制的不连续性,会使转子侧电流产生抖振,因此在切换控制中加入了饱和函数,使系统在边界层内产生准滑模运动,以减小转子电流的抖振,降低定子电压的谐波畸变率。利用PSCAD对并网前的空载运行、并网时的过渡过程的仿真结果表明,传统的PI控制相比,该策略对各种扰动具有更好的鲁棒性。

With combination of integral variable structure control （ IVSC ） and field-oriented vector control technique, a control strategy was presented for smooth no-load cutting-in of variable-speed constant-frequency double-fed wind-power generator. In order to get strong robustness to many kinds of disturbances in global range and excellent dynamic performance, the control system consists of two current controllers using IVSC and one voltage deviation controller based on variable integration rate. Because the discontinuousness of IVSC may produce chattering of rotor current, the saturation function was employed in switch control, which can make the system produce quasi slide mode movement in boundary layer, accordingly decrease the chattering of rotor current and reduce the harmonic distortion rate of stator voltage. The proposed control method is simulated with PSCAD for no-load operation before the cutting-in and the transi- ent process of cutting-in respectively, and the results indicate that the method has better robustness to many kinds of disturbances in comparison with the traditional PI control.