中文摘要：

基于滞环伪滑模变结构算法，提出一种分程控制方法。该方法采用滞环降低抖动频率，并通过改变反馈作用大小来进一步优化换流电路的工作性能。分程控制充分利用级联DVR电路的特点，根据电网电压情况将DVR输出电压划分为不同范围，针对不同程度的畸变投入相应数量的功率模块，使控制系统能够优化响应速度，保证受控电压精确跟踪参考信号，维持电压稳定。理论分析表明该算法使功率模块间歇工作，这样可以降低开关损耗，同时分析了系统参数对控制特性以及切换频率的影响。根据DVR数学模型进行仿真，结果表明分程控制算法具有良好的鲁棒性与实时．陛，能够快速消除电压谐波及凹陷。

英文摘要：

Based on pseudo-sliding mode with hysteresis loop a split ranging variable structure system（VSS） control scheme is presented to decrease the switching frequency and improve the control performance. By the proposed scheme the output control signal of cascaded DVR is scaled according to power grid situation, and then different number of power cells are/is brought into operation according to variable magnitude of voltage aberration, thus the response speed of control system can be increased and the controlled voltage is forced to follow reference signal precisely. This algorithm makes the power cells work intermittently at optimized switching mode in order to reduce system losses. The influences of system parameters on the system robustness and switching frequency were analyzed. Simulation based on cascaded DVR model shows that the proposed control method can eliminate voltage harmonics and compensate voltage sags quickly, and the results are satisfactory.