VSC-HVDC变量软约束期望区间跟踪的EMPC设计
Design for Explicit Model Predictive Control Based on Expected Interval Tracking and Variable Soft Constraint of VSC-HVDC System
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摘要: 根据直流线路电压与电流之间的非线性关系,建立了电压源换流器型高压直流(VSCHVDC)输电系统的分段仿射模型。针对带状态和输入约束的分段仿射系统动态变化快的特点,弥补模型预测控制滚动优化计算使得系统响应速度变慢、实时性降低的缺点。采用离线计算和在线分析相结合的显式模型预测控制方法,将反复在线滚动优化计算转化为简单的查表过程。通过期望区间跟踪偏差项和添加变量软约束的方法优化VSC-HVDC系统的输出轨迹。仿真结果表明,所设计的显式模型预测控制器具有良好的动态性能和稳态性能,能够较好地抑制输出轨迹的波动,与模型预测控制相比,动态响应更快,控制的实时性更强。Abstract: Based on the nonlinear relationship between the voltage and current of the DC link,apiecewise affine model（PWA）of voltage source converter based high-voltage direct-current（VSC-HVDC）system is developed. According to the characteristics of fast dynamic change of PWA system with state and input constraints,this paper makes up for the shortcomings of model predictive control（MPC）causing slowed-down system response and degraded real-time performance.Explicit model predictive control（EMPC）combined with off-line calculation and on-line analysis is used to transform repeated online rolling optimization calculation into a simple table lookup process.The output trajectory of the VSC-HVDC system by means of expected interval tracking deviation and adding the variable soft constraints is optimized.Simulation results show that the explicit model predictive controller has good dynamic performance and steady performance,while able to suppress fluctuations of output trajectory.Compared with the MPC,the dynamic response of EMPC is faster,and the real-time of EMPC is stronger.
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