In order to solve the problem of weighting factors selection in the conventional finite-control-set model predictive control for a grid-connected three-level inverter,an improved multi-objective model predictive contr...In order to solve the problem of weighting factors selection in the conventional finite-control-set model predictive control for a grid-connected three-level inverter,an improved multi-objective model predictive control without weighting factors based on hierarchical optimization is proposed.Four control objectives are considered in this strategy.The grid current and neutral-point voltage of the DC-link are taken as the objectives in the first optimization hierarchy,and by using fuzzy satisfaction decision,several feasible candidates of voltage vectors are determined.Then,the average switching frequency and common-mode voltage are optimized in the second hierarchy.The average ranking criterion is introduced to sort the objective functions,and the best voltage vector is obtained to realize the coordinated control of multiple objectives.At last,the effectiveness of the proposed strategy is verified by simulation results.展开更多
For a DC distributed power system, system stability can be predicted by dividing it into source and load subsystems, and then applying the Nyquist criterion to the impedance interaction between the source and load mod...For a DC distributed power system, system stability can be predicted by dividing it into source and load subsystems, and then applying the Nyquist criterion to the impedance interaction between the source and load model.However, the generalized Nyquist criterion is extremely complicated and cannot directly reveal effective control strategies to reduce interaction problems of cascade threephase AC systems.Specifically, as a current force rectifier,this characteristic makes it difficult to judge the stability of a cascade three-phase Vienna AC system.To deal with the aforementioned problems, a simplified small signal stability criterion is presented for an AC distributed power system.Based on the criterion, the small signal model and impedance based on the reduced order model in the dq domain are studied theoretically.For the instability issue,an impedance regulator design method is presented.The correctness of the simplified stability criterion and the effectiveness of the proposed impedance regulator method are validated by extensive simulation and experiment.展开更多
基金Supported by the Key Research and Development Program of Hunan Province of China(2018GK2031)the Independent Research Project of State Key Laboratory of Advance Design and Manufacturing for Vehicle Body(71965005)+2 种基金the Innovative Construction Program of Hunan Province of China(2019RS1016)the 111 Project of China(B17016)the Excellent Innovation Youth Program of Changsha of China(KQ2009037).
文摘In order to solve the problem of weighting factors selection in the conventional finite-control-set model predictive control for a grid-connected three-level inverter,an improved multi-objective model predictive control without weighting factors based on hierarchical optimization is proposed.Four control objectives are considered in this strategy.The grid current and neutral-point voltage of the DC-link are taken as the objectives in the first optimization hierarchy,and by using fuzzy satisfaction decision,several feasible candidates of voltage vectors are determined.Then,the average switching frequency and common-mode voltage are optimized in the second hierarchy.The average ranking criterion is introduced to sort the objective functions,and the best voltage vector is obtained to realize the coordinated control of multiple objectives.At last,the effectiveness of the proposed strategy is verified by simulation results.
基金supported by the National Natural Science Fund of China (No.51677151)National Natural Science Youth Fund of China (No.51507138)+1 种基金the Major Scientific and Technological Innovation Projects of Shaanxi Province, China (No.2015ZKC02-01)International Exchange And Cooperation Project of Key R&D Program in Shaanxi (No.2017KW-035)
文摘For a DC distributed power system, system stability can be predicted by dividing it into source and load subsystems, and then applying the Nyquist criterion to the impedance interaction between the source and load model.However, the generalized Nyquist criterion is extremely complicated and cannot directly reveal effective control strategies to reduce interaction problems of cascade threephase AC systems.Specifically, as a current force rectifier,this characteristic makes it difficult to judge the stability of a cascade three-phase Vienna AC system.To deal with the aforementioned problems, a simplified small signal stability criterion is presented for an AC distributed power system.Based on the criterion, the small signal model and impedance based on the reduced order model in the dq domain are studied theoretically.For the instability issue,an impedance regulator design method is presented.The correctness of the simplified stability criterion and the effectiveness of the proposed impedance regulator method are validated by extensive simulation and experiment.
