In this paper, a modified simple penalty function is proposed for a constrained nonlinear programming problem by augmenting the dimension of the program with a variable that controls the weight of the penalty terms. T...
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In this paper, a modified simple penalty function is proposed for a constrained nonlinear programming problem by augmenting the dimension of the program with a variable that controls the weight of the penalty terms. This penalty function enjoys improved smoothness. Under mild conditions, it can be proved to be exact in the sense that local minimizers of the original constrained problem are precisely the local minimizers of the associated penalty problem.
A packing problem for irregular 3D objects approximated by polyhedra is presented. The objects have to be packed into a cuboid of minimum height under continuous rotations, translations and minimum allowable distances...
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In this paper, we study first- and second-order necessary conditions for nonlinear programming problems from the viewpoint of exact penalty functions. By applying the variational description of regular subgradients, w...
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In this paper, we study first- and second-order necessary conditions for nonlinear programming problems from the viewpoint of exact penalty functions. By applying the variational description of regular subgradients, we first establish necessary and sufficient conditions for a penalty term to be of KKT-type by using the regular subdifferential of the penalty term. In terms of the kernel of the subderivative of the penalty term, we also present sufficient conditions for a penalty term to be of KKT-type. We then derive a second-order necessary condition by assuming a second-order constraint qualification, which requires that the second-order linearized tangent set is included in the closed convex hull of the kernel of the parabolic subderivative of the penalty term. In particular, for a penalty term with order , by assuming the nonpositiveness of a sum of a second-order derivative and a third-order derivative of the original data and applying a third-order Taylor expansion, we obtain the second-order necessary condition.
Soft Open Point (SOP) refers to a novel power electronic device installed in distribution system to replace the traditional tie switch. The application of SOP will promote the flexibility and resilience of the distrib...
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ISBN:
(纸本)9781509043033
Soft Open Point (SOP) refers to a novel power electronic device installed in distribution system to replace the traditional tie switch. The application of SOP will promote the flexibility and resilience of the distribution system. Under a fault condition, SOP enables to provide voltage support and helps to expand the scope of power supply for the supply restoration. In this paper, a supply restoration model of distribution system is established based on SOP, which is essentially a complex nonlinear programming problem. The primal-dual interior-point algorithm is adopted to solve the problem, which can find the optimal solution rapidly and accurately. Then, the modified IEEE 33-node system is used to verify the effectiveness and efficiency of the proposed method.
This paper proposes a new state estimation method modeled as a nonlinear programming problem with equality constraints. The majority of the estimated state estimation methods work with a set of measurements composed o...
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ISBN:
(纸本)9781424415823
This paper proposes a new state estimation method modeled as a nonlinear programming problem with equality constraints. The majority of the estimated state estimation methods work with a set of measurements composed of active and reactive power flows on branches, active and reactive injection power on nodes, and nodal voltage magnitudes. In this method, the current magnitude branch measurements are considered in a simpler and direct manner, increasing the global redundancy of the system. Tests were carried out with several systems widely known in the literature and the results obtained confirmed the efficiency of the method. The method can be applied both to transmission and distribution systems and permit the inclusion of the inequality constraints and the bad data processing.
This paper presents a new,approach for solving optimal control problems for switched systems with prespecified order of the sequence of subsystems. For such problems, we need to seek both the optimal switching instant...
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ISBN:
(纸本)9781424487363
This paper presents a new,approach for solving optimal control problems for switched systems with prespecified order of the sequence of subsystems. For such problems, we need to seek both the optimal switching instants and the optimal continuous inputs. The optimal control problem for hybrid systems is transcribed into an equivalent problem parameterized by the switching instants and the control vectors. Through the discretization of the control space, the control vector is approximated by the B-spline functions. In order to search for the optimal switching instants, we introduce the normalized time variable and do normalized treatment for the control arcs. The optimal switching control problem is converted to a nonlinear programming problem. The control profiles and switching instants act as decision variables. Two examples are solved using the proposed method so as to demonstrate the effectiveness of the method proposed.
State estimation (SE) helps to determine the most-likely steady-state operation of microgrids based on field measurements. It is a fundamental data processing tool responsible for supporting and increasing system visi...
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ISBN:
(纸本)9781665453554
State estimation (SE) helps to determine the most-likely steady-state operation of microgrids based on field measurements. It is a fundamental data processing tool responsible for supporting and increasing system visibility and filtering errors that may appear in real-time measurements, system topology, and parameters. Hence, it serves as a reliable basis for the energy management system (EMS) infrastructure. Existing SE methods are based on Newton-like algorithms rather than using specific optimization. Nevertheless, SE can always be reduced to a constrained optimization problem, with the objective of minimizing a given criterion, e.g., weighted least squares (WLS) or weighted least absolute value (WLAV). In this context, this paper presents two unbalanced three-phase AC SE methods based on mathematical programming for microgrids. The effectiveness and validity of the proposed state estimation approach are demonstrated on a real microgrid located at the State University of Campinas, in Brazil, and over one widely known IEEE test system. The method can be easily adapted to other microgrids with different configurations, distributed energy resources, and measurements. Results show that the proposed methods report high accuracy, but the state estimator based on WLS is faster than the WLAV.
This paper presents a new semi-mechanization method for proving the validity of an inequality conjecture about convex n-gon when n = 8 and gaining headway in proving it when n = 9. This conjecture is generally convert...
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ISBN:
(纸本)9781595934802
This paper presents a new semi-mechanization method for proving the validity of an inequality conjecture about convex n-gon when n = 8 and gaining headway in proving it when n = 9. This conjecture is generally converted into a global optimization problem which is related to Heilbronn triangular problem. For solving it, the bottleneck is the complexity increasing very quickly with n. In the proposed algorithm, to reduce the dimension of freedom we first analyze the properties of the optimal configurations and try to obtain the strict polynomial inequality and equality conditions as many as possible. After the precondition, the mechanization method can be implemented to solve this nonlinear optimization problem, so we call the overall approach as semi-mechanization method. We hope our algorithm will be useful for proving the conjecture with larger value of n.
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