三电平APF谐波电流及中点电位平衡控制

针对三电平有源电力滤波器，提出一种基于带柔化输入的模型预测控制方法用于谐波补偿。同时，为避免直流侧中点电位的波动和偏移问题给系统稳定性带来的不利影响，采用基于平衡因子和简化SVPWM算法的中点电位平衡控制策略。模型预测控制方法根据实际有源电力滤波器控制系统设计电流预测模型，同时将预测输出与实际输出的偏差及时反馈，结合滚动优化，使有源电力滤波器的补偿电流快速跟踪参考值。直流侧母线电压控制采用简化三电平SVPWM算法，简化了算法同时保证了中点电位平衡。建立了APF预测电流控制的等效模型，并进行了仿真验证。所提方法有效柔化电流输入从而减小超调，较传统预测控制方法更为稳定，减少了谐波含量和改善了补偿精度，并保证了直流母线电压的稳定和中点电位快速平衡。仿真结果验证了所提控制策略的有效性与可行性。

Control of Harmonic Current and Neutral-point Potential Balance for Three-level APF

For a three-level active power filter (APF), a model predictive control (MPC) method with softened input is proposed for harmonic compensation. At the same time, a neutral-point potential balance control strategy based on the balance factor and simplified SVPWM algorithm is adopted to avoid the adverse effects of the fluctuation and migration of DC-side neutral point potential on the system stability. The MPC method is used to design a current prediction model based on the actual APF control system. Meanwhile, the deviation of the predicted output from the actual output is fed back in time so that the compensation current of the APF can quickly track the reference value by combing the rolling optimization. The control of DC-side bus voltage adopts a simplified three-level SVPWM algorithm, thus simplifying the algorithm and ensuring the neutral point potential balance. An equivalent model of APF predictive current control is established, which is verified through simulations. The proposed method effectively softens the current input and thus suppress the overshoot, which is more stable than the traditional predictive control method. It reduces the harmonic content, improves the compensation accuracy, and ensures the stability of DC bus voltage and the fast balance of neutral point potential. Simulation results verify the effectiveness and feasibility of the proposed control strategy.