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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Study on Fault Restoration Strategy of Distribution Systems with Colored Petri Net Model

Tsai, Hung-Ying 12 June 2003 (has links)
With load growth of distribution systems, it becomes very complicated for dispatchers to obtain restoration plan for unfaulted but out-of-service areas. In this thesis, a rule-based expert system with a colored Petri net (CPN) inference model is developed. The CPN models of distribution components such as four-way line switches are proposed to derive the proper switching operation plan for service restoration by applying reasoning in the CPN. After main transformer contingency has been identified and isolated, it is highly possible that the out of service customers can not be restored completely because of the shortage of capacity reserve. The feeders which serve more key customers with higher service priority will have better chance to be selected for restoration. With the system reconfiguration to cover the load change of service zones over a longer period, during the process of switching operation, the maximum load demand of out-of-service area over the restoration time is considered in the CPN. To prevent the over-unbalance tripping of distribution feeders during switching operation process, the maximum tolerable current unbalance between any two phases is also considered in the CPN model. To assure the restoration plan complying with the operation regulation, heuristic rules based on the standard operation procedures of Taipower distribution system are included in the best first search of the CPN. A Taipower distribution system with 67 feeders is selected for computer simulation in this thesis to demonstrate the effectiveness of the proposed methodology. It is found that the service restoration of distribution systems can be obtained very efficiently by applying the proposed CPN model.
2

Integrating Expert System and Geographic Information System for Spatial Decision Making

Shesham, Sriharsha 01 December 2012 (has links)
Spatial decision making is a process of providing an effective solution for a problem that encompasses semi-structured spatial data. It is a challenging task which involves various factors to consider. For example, in order to build a new industry, an appropriate site must be selected for which several factors have to be taken into consideration. Some of the factors, which can affect the decision in this particular case, are air pollution, noise pollution, and distance from living areas, which makes the decision difficult. The geographic information systems (GIS) and the expert systems (ES) have many advantages in solving problems in their prospective areas. Integrating these two systems will benefit in solving spatial decision making problems. In the past, many researchers have proposed integrating systems which extracts the data from the GIS and saves it in the database for decision making. Most of the frameworks which have been developed were system dependent and are not properly structured. So it is difficult to search the data. This thesis proposes a framework which extracts the GIS data and processes it with the help of ES decision making capabilities to solve the spatial decision making problem. This framework is named GeoFilter. This research classifies various types of mechanisms that can be used to integrate these two systems.
3

Asset Management in Electricity Transmission Enterprises: Factors that affect Asset Management Policies and Practices of Electricity Transmission Enterprises and their Impact on Performance

Crisp, Jennifer J. January 2004 (has links)
This thesis draws on techniques from Management Science and Artificial Intelligence to explore organisational aspects of asset management in electricity transmission enterprises. In this research, factors that influence policies and practices of asset management within electricity transmission enterprises have been identified, in order to examine their interaction and how they impact the policies, practices and performance of transmission businesses. It has been found that, while there is extensive literature on the economics of transmission regulation and pricing, there is little published research linking the engineering and financial aspects of transmission asset management at a management policy level. To remedy this situation, this investigation has drawn on a wide range of literature, together with expert interviews and personal knowledge of the electricity industry, to construct a conceptual model of asset management with broad applicability across transmission enterprises in different parts of the world. A concise representation of the model has been formulated using a Causal Loop Diagram (CLD). To investigate the interactions between factors of influence it is necessary to implement the model and validate it against known outcomes. However, because of the nature of the data (a mix of numeric and non-numeric data, imprecise, incomplete and often approximate) and complexity and imprecision in the definition of relationships between elements, this problem is intractable to modelling by traditional engineering methodologies. The solution has been to utilise techniques from other disciplines. Two implementations have been explored: a multi-level fuzzy rule-based model and a system dynamics model; they offer different but complementary insights into transmission asset management. Each model shows potential for use by transmission businesses for strategic-level decision support. The research demonstrates the key impact of routine maintenance effectiveness on the condition and performance of transmission system assets. However, performance of the transmission network, is not only related to equipment performance, but is a function of system design and operational aspects, such as loading and load factor. Type and supportiveness of regulation, together with the objectives and corporate culture of the transmission organisation also play roles in promoting various strategies for asset management. The cumulative effect of all these drivers is to produce differences in asset management policies and practices, discernable between individual companies and at a regional level, where similar conditions have applied historically and today.
4

Evolutionary Belief Rule based Explainable AI to Predict Air Pollution

Zisad, Sharif Noor January 2023 (has links)
This thesis presents a novel approach to make Artificial Intelligence (AI) more explainable by using a Belief Rule Based Expert System (BRBES). A BRBES is a type of expert system that can handle both qualitative and quantitative information under uncertainty and incompleteness by using if-then rules with belief degrees. The BRBES can model the human inference process and provide transparent and interpretable reasoning for its decisions. However, designing a BRBES requires tuning several parameters, such as the rule weights, the belief degrees, and the inference parameters. To address this challenge, this thesis report proposes to use a Differential Evolution (DE) algorithm to optimize these parameters automatically. A DE algorithm such as BRB adaptive DE (BRBaDE) and Joint Optimization of BRB is a metaheuristic that optimizes a problem by iteratively creating new candidate solutions by combining existing ones according to some simple formulae. The DE algorithm does not require any prior knowledge of the problem or its gradient, and can handle complex optimization problems with multiple objectives and constraints. This model can provide explainability by using different model agnostic method including Local Interpretable Model-agnostic Explanations (LIME) and SHapley Additive exPlanations (SHAP). The proposed approach is applied to calculate Air Quality Index (AQI) using particle data. The results show that the proposed approach can improve the performance and explainability of AI systems compared to other existing methods. Moreover, the proposed model can ensure the balance between accuracy and explainablity in comparison to other models.

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