In this paper best approximation by reciprocals of functions of a subspace U_n=span (u_1,…,u_n)satisfying coefficient constraints is considered.We present a characterization of best approximations.When(u_1,…,u_n)is ...In this paper best approximation by reciprocals of functions of a subspace U_n=span (u_1,…,u_n)satisfying coefficient constraints is considered.We present a characterization of best approximations.When(u_1,…,u_n)is a Descartes system an explicit characterization of best approximations by equioscillations is given.Existence and uniqueness results are shown. Moreover,the theory is applied to best approximaitons by reciprocals of polynomials.展开更多
Determining security/stability boundaries is a common and critical means of preventing cascading failures induced by voltage-related issues,which represents one of the major challenges in bulk power systems.However,tr...Determining security/stability boundaries is a common and critical means of preventing cascading failures induced by voltage-related issues,which represents one of the major challenges in bulk power systems.However,traditional approaches suffer from conservative issues and heavy computational burdens.To address these challenges,the concept of an autonomous-synergic voltage security region(AS-VSR)and the corresponding dynamic constraint coefficient pruning(DCCP)computation method,which fully consider the volt/var characteristics of bulk power systems,are proposed in this letter.Both linearized and nonlinearized robust optimization problems are introduced to obtain accurate results.The computational accuracy,time cost,and advantages of autonomous-synergic control are observed in the simulation results.展开更多
文摘In this paper best approximation by reciprocals of functions of a subspace U_n=span (u_1,…,u_n)satisfying coefficient constraints is considered.We present a characterization of best approximations.When(u_1,…,u_n)is a Descartes system an explicit characterization of best approximations by equioscillations is given.Existence and uniqueness results are shown. Moreover,the theory is applied to best approximaitons by reciprocals of polynomials.
基金supported in part by the National Natural Science Foundation of China (No.52007017)Fundamental Research Funds for the Central Universities (No.2020CDJQY-A027)。
文摘Determining security/stability boundaries is a common and critical means of preventing cascading failures induced by voltage-related issues,which represents one of the major challenges in bulk power systems.However,traditional approaches suffer from conservative issues and heavy computational burdens.To address these challenges,the concept of an autonomous-synergic voltage security region(AS-VSR)and the corresponding dynamic constraint coefficient pruning(DCCP)computation method,which fully consider the volt/var characteristics of bulk power systems,are proposed in this letter.Both linearized and nonlinearized robust optimization problems are introduced to obtain accurate results.The computational accuracy,time cost,and advantages of autonomous-synergic control are observed in the simulation results.
