Selective harmonic elimination(SHE) in multilevel inverters is an intricate optimization problem that involves a set of nonlinear transcendental equations which have multiple local minima. A new advanced objective fun...Selective harmonic elimination(SHE) in multilevel inverters is an intricate optimization problem that involves a set of nonlinear transcendental equations which have multiple local minima. A new advanced objective function with proper weighting is proposed and also its efficiency is compared with the objective function which is more similar to the proposed one. To enhance the ability of the SHE in eliminating high number of selected harmonics, at each level of the output voltage, one slot is created. The SHE problem is solved by imperialist competitive algorithm(ICA). The conventional SHE methods cannot eliminate the selected harmonics and satisfy the fundamental component in some ranges of modulation indexes. So, to surmount the SHE defect, a DC-DC converter is applied. Theoretical results are substantiated by simulations and experimental results for a 9-level multilevel inverter. The obtained results illustrate that the proposed method successfully minimizes a large number of identified harmonics which consequences very low total harmonic distortion of output voltage.展开更多
Forhigh power applications,multilevel converters have many advantages in comparison with other circuit topologies with output transformers. Cascaded inverters are one type of multilevel converters,they are easy to imp...Forhigh power applications,multilevel converters have many advantages in comparison with other circuit topologies with output transformers. Cascaded inverters are one type of multilevel converters,they are easy to implement,very suitable for modularized layout and packaging.Their manufacturing cost is low.A multilevel PWM technique,called as General Technique of Selected Harmonics Elimination (GTSHE) ,is proposed in the paper. A general harmonic elimination equation for N cells,M pulses per half cycle,nth harmonic is derived,and verified by simulation results.展开更多
随着分布式电源和电动汽车在配电网的渗透率不断提高,越来越多的电力电子设备接入使得配电系统的谐波治理面临新的挑战。该文从系统耦合特性分析出发,提出一种基于相对增益矩阵(relative gain array,RGA)的多功能并网逆变器(multifuncti...随着分布式电源和电动汽车在配电网的渗透率不断提高,越来越多的电力电子设备接入使得配电系统的谐波治理面临新的挑战。该文从系统耦合特性分析出发,提出一种基于相对增益矩阵(relative gain array,RGA)的多功能并网逆变器(multifunctional grid-tied inverter,MFGTI)协同谐波补偿优化方法。通过引入RGA耦合度分析,构建补偿源与节点电压间的传递特性模型,建立包含耦合度、独立性和综合效能的多维评价指标,实现补偿源的最优配置;提出基于最小二乘法的补偿电流优化算法,在考虑设备容量约束下确定最优补偿策略。结合工程实际,构建综合电气距离和谐波敏感度的评价指标,提出无需量测系统所有节点谐波数据的量测点筛选方法。算例对比分析和仿真验证结果表明,所提方法能够协调多台MFGTI对配电系统的谐波进行综合补偿,有效降低系统谐波污染水平。展开更多
二阶选择谐波重复控制(second order selective harmonic repetitive control, SOSHRC)策略因其良好的频率适应性和动态性能被广泛应用于并网逆变器控制中。针对传统SOSHRC策略的稳定性分析方法复杂、稳定性标准较为保守等问题,提出一...二阶选择谐波重复控制(second order selective harmonic repetitive control, SOSHRC)策略因其良好的频率适应性和动态性能被广泛应用于并网逆变器控制中。针对传统SOSHRC策略的稳定性分析方法复杂、稳定性标准较为保守等问题,提出一种新型二阶选择谐波重复-比例控制(second order selective harmonic repetitive control and proportional control, SOSHRC-PC)。首先,设计新型SOSHRC的结构和原理,并介绍新型SOSHRC-PC控制策略。然后,分析新型SOSHRC-PC控制器的稳定性和参数设计方法。最后,搭建基于新型二阶(6k±1)次谐波重复-比例控制的三相并网逆变器模型,仿真结果表明所提的控制策略具有良好的稳态和动态性能。展开更多
文摘Selective harmonic elimination(SHE) in multilevel inverters is an intricate optimization problem that involves a set of nonlinear transcendental equations which have multiple local minima. A new advanced objective function with proper weighting is proposed and also its efficiency is compared with the objective function which is more similar to the proposed one. To enhance the ability of the SHE in eliminating high number of selected harmonics, at each level of the output voltage, one slot is created. The SHE problem is solved by imperialist competitive algorithm(ICA). The conventional SHE methods cannot eliminate the selected harmonics and satisfy the fundamental component in some ranges of modulation indexes. So, to surmount the SHE defect, a DC-DC converter is applied. Theoretical results are substantiated by simulations and experimental results for a 9-level multilevel inverter. The obtained results illustrate that the proposed method successfully minimizes a large number of identified harmonics which consequences very low total harmonic distortion of output voltage.
文摘Forhigh power applications,multilevel converters have many advantages in comparison with other circuit topologies with output transformers. Cascaded inverters are one type of multilevel converters,they are easy to implement,very suitable for modularized layout and packaging.Their manufacturing cost is low.A multilevel PWM technique,called as General Technique of Selected Harmonics Elimination (GTSHE) ,is proposed in the paper. A general harmonic elimination equation for N cells,M pulses per half cycle,nth harmonic is derived,and verified by simulation results.
文摘随着分布式电源和电动汽车在配电网的渗透率不断提高,越来越多的电力电子设备接入使得配电系统的谐波治理面临新的挑战。该文从系统耦合特性分析出发,提出一种基于相对增益矩阵(relative gain array,RGA)的多功能并网逆变器(multifunctional grid-tied inverter,MFGTI)协同谐波补偿优化方法。通过引入RGA耦合度分析,构建补偿源与节点电压间的传递特性模型,建立包含耦合度、独立性和综合效能的多维评价指标,实现补偿源的最优配置;提出基于最小二乘法的补偿电流优化算法,在考虑设备容量约束下确定最优补偿策略。结合工程实际,构建综合电气距离和谐波敏感度的评价指标,提出无需量测系统所有节点谐波数据的量测点筛选方法。算例对比分析和仿真验证结果表明,所提方法能够协调多台MFGTI对配电系统的谐波进行综合补偿,有效降低系统谐波污染水平。
文摘二阶选择谐波重复控制(second order selective harmonic repetitive control, SOSHRC)策略因其良好的频率适应性和动态性能被广泛应用于并网逆变器控制中。针对传统SOSHRC策略的稳定性分析方法复杂、稳定性标准较为保守等问题,提出一种新型二阶选择谐波重复-比例控制(second order selective harmonic repetitive control and proportional control, SOSHRC-PC)。首先,设计新型SOSHRC的结构和原理,并介绍新型SOSHRC-PC控制策略。然后,分析新型SOSHRC-PC控制器的稳定性和参数设计方法。最后,搭建基于新型二阶(6k±1)次谐波重复-比例控制的三相并网逆变器模型,仿真结果表明所提的控制策略具有良好的稳态和动态性能。
