This paper proposes a novel integrated restoration method for transmission (TS) and active distribution systems (DS). The proposed method capitalizes on multi-microgrids' (MMGs') enhanced controllability acros...
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This paper proposes a novel integrated restoration method for transmission (TS) and active distribution systems (DS). The proposed method capitalizes on multi-microgrids' (MMGs') enhanced controllability across multiple levels of the modern bulk power system (BPS) to develop a new constraint hierarchy approach, formulating the restoration problem as three mixed-integer linear programming (MILP) subproblems. Based on the constraint hierarchy approach, the coordinated load restoration process is able to overcome the multiple regulations and jurisdictions limitations imposed on sharing resources between DS- and TS-level, while significantly reducing computational burden compared to non-linear methods. This critical feature not addressed in the literature can lead to unfeasible solutions and meaningfully compromise the restoration performance. Moreover, the developed method can unlock and coordinate the previously inaccessible resource transactions between different BPS levels, i.e., local-local (DS) and global-local (TS) levels. Therefore, significantly improving load pick-up capacity, service capability, and restoration time at both DS- and TS-level. Finally, comparative case studies with state-of-the-art and benchmark strategies are used to validate the proposed method. The obtained results showcase the effectiveness and advantages of the proposed method in enhancing the coordination of integrated TS- and active DS-restoration process.
constraint programming is a powerful tool for modeling and solving various problems. Especially, soft constraints are useful since they enable the treatment of over- and under-constrained real-world problems by relaxi...
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ISBN:
(纸本)9798350342734
constraint programming is a powerful tool for modeling and solving various problems. Especially, soft constraints are useful since they enable the treatment of over- and under-constrained real-world problems by relaxing conflicting constraints and introducing default constraints. constraint hierarchies provide a soft constraint framework that introduces hierarchical preferences called strengths. In a constraint hierarchy, constraints are associated with strengths such as required, strong, medium, and weak, and a solution is obtained to maximally satisfy stronger constraints in the sense of a given solution criterion. In this paper, we propose three methods based on binary search for solving constraint hierarchies over finite domains by using a criterion called unsatisfied-count-better. Our methods solve constraint hierarchies by encoding them into ordinary constraint satisfaction problems and repeatedly solving the encoded problems with an external solver. We also present the implementations of our methods and the results of the experiment that we conducted to evaluate them.
Optimality Theory (OT) and Exemplar Theory (ET) are two enchanting theories to many scholars, but each still faces criticism and remaining persistent problems. Application of both theories to areas in linguistics wher...
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Optimality Theory (OT) and Exemplar Theory (ET) are two enchanting theories to many scholars, but each still faces criticism and remaining persistent problems. Application of both theories to areas in linguistics where conflicts may arise has been attempted, but still the suitability of combining the two theories to resolve contradictions awaits further analysis and verification. This article takes Polish singular-plural pairs as the object of study and argues in favor of an OT-ET combined model of analyzing the linguistic phenomenon. First, an underlying representation is identified to be the input in an OT analysis. Then two main changes are recognized between the input and output, and are regarded as instances of positional neutralization, and their relevant constraints and constraint hierarchies are presented. Following this, challenges are posed to OT despite its merits. It turns out that the combined OT-ET model works well, with historical development, underspecification, constraint hierarchy, and resemblance to existing word clouds, among others, all playing relevant parts. The current study adds to the extensiveness of language data analyzed for or against combining OT and ET, and sketches the analysis pattern of thus doing, with a view to offering more real-life language materials for an OT-ET combined model.
constraints allow the declarative specification of various problems in many fields. In particular, constraint hierarchies that enable soft constraints with hierarchical preferences are useful for programming interacti...
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ISBN:
(纸本)9781450376785
constraints allow the declarative specification of various problems in many fields. In particular, constraint hierarchies that enable soft constraints with hierarchical preferences are useful for programming interactive graphical applications. However, it is still difficult to handle constraint hierarchies with nonlinear constraints. This paper proposes an algorithm for solving constraint hierarchies possibly with nonlinear constraints. Instead of directly solving a constraint hierarchy, it successively generates and solves ordinary constraint problems by using an external SMT solver. The results of our experiments show that the algorithm is able to find accurate constraint hierarchy solutions.
Feature models have been widely adopted to reuse the requirements of a set of similar products in a domain. When constructing feature models, it is difficult to always ensure the consistency of feature models. Therefo...
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Feature models have been widely adopted to reuse the requirements of a set of similar products in a domain. When constructing feature models, it is difficult to always ensure the consistency of feature models. Therefore, tolerating inconsistencies is important during the construction of feature models. The usual way of tolerating inconsistencies is to find the minimal unsatisfiable core. However, identifying the minimal unsatisfiable core is time-consuming, which decreases itself the practicability. In this paper, we propose a priority based approach to tolerating inconsistencies in feature models efficiently. The basic idea of our approach is to find the weaker unsatisfied constraints, while keeping the rest of the feature model consistent. Our approach tolerates inconsistencies with the help of priority based operations while building feature models. To this end, we adopt the constraint hierarchy theory to express the degree of domain analysts' confidence on constraints (i.e. the priorities of constraints) and tolerate inconsistencies in feature models. Experiments have been conducted to demonstrate that our system can scale up to large feature models.
CP-networks are an elegant and compact qualitative framework for express preference, in which we can represent and reason about preference rankings given conditional preference statements. However, represent constrain...
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ISBN:
(纸本)038723151X
CP-networks are an elegant and compact qualitative framework for express preference, in which we can represent and reason about preference rankings given conditional preference statements. However, represent constraints in such framework is one difficult problem. We therefore propose a new approach, i.e. mapping CP-networks to constraint hierarchy, thus we can reason preferences with constraint solving algorithms. We compare it with related work finally.
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