海上风电柔性直流输电变流器P-DPC控制研究

Predictive Direct Power Control Strategy for Offshore Wind Power VSC-HVDC Converter

基于预测控制原理,根据瞬时功率理论计算出每个开关周期开始时变流器侧输入电压矢量平均值,结合空间矢量调制和直流母线电压外环控制,消除在开关周期结束时产生的有功、无功功率跟踪误差,从而直接控制变流器的有功、无功功率,达到稳态无静差控制。同时,对外环控制器进行理论分析与设计。与传统直接功率控制方法相比,预测直接功率控制(P-DPC)的特点为无需检测电网电压相位信息(如锁相环等)、实施同步旋转坐标变化和电流环解耦控制;开关频率固定,减少了跟踪误差带来的干扰以及参数不准确造成的解耦不彻底等问题,提高了系统的稳定性;在两相静止坐标系下即可实现网侧单位功率因数运行。采用Matlab/Simulink构建PWM-VSC系统仿真模型进行仿真,结果证明了该控制方法的可行性和有效性,为海上风电场柔性直流输电变流器数字控制系统提供了一种可行的控制方案。

The developed DPC scheme is based on predictive control theory to achieve direct control of instantaneous active and reactive power of the converter. For this purpose, at the beginning of each switching period in the sense of deadbeat control. Therefore it can eliminate the active and reactive power tracking errors at the end of switching period. Meanwhile, combined with space vector modulation （SVM） and the DC bus voltage outer-loop analysis and design, it can obtain the predictive direct power control strategy （P-DPC）. When compared to the traditional DPC method, the main features of the proposed P-DPC method, are that it does not need to detect the grid voltage vector position （such as phase-locked loop-PLL, etc.）, transfer them into synchronous rotating reference frame and inner-current loop decoupling control. Its switching frequency is fixed. The uncompleted decoupling problem caused by interference of tracking errors and inaccurate parameters are well solved, that improve the system＇s stability. The unity power factor operation can be realized in stationary reference frame. A PWM-VSC model is set up feasibility and effectiveness of the proposed offshore VSC-HVDC engineering. in Matlab/simulation software, and the results show the control methods, which can available for reference in