Branch Current State Estimation Method for Power Distribution Systems

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Title: Branch Current State Estimation Method for Power Distribution Systems
Author: Jung, Jae Sung
Advisors: Mesut E. Baran, Committee Chair
Winser E. Alexander, Committee Member
Subhashish Bhattacharya, Committee Member
Sujit Ghosh, Committee Member
Abstract: Effective management of distribution systems requires analysis tools that can estimate the state of the system (the operating condition). This thesis aims at development of new analysis tools for this purpose. The main tool is the state estimator that will use historical data and the real-time data to estimate the state of the system determined by voltage at all of the nodes of a distribution feeder. This thesis considers the incorporation of voltage measurements in a branch-current-based state estimation (BCSE) program. Original BCSE is designed to include only power and current measurements. The motivation for enhancing BCSE is that with the adoption of large scale automated meter infrastructure (AMI) technologies, voltage measurements will be available at the distribution level. Hence, including these measurements has the potential to improve the accuracy of state estimation. Furthermore, this thesis presents a statistical technique for assessing the BCSE performance. For statistical analysis, 300 Monte Carlo simulations are performed. The overall performance including bias, consistency and quality of estimates is evaluated in order to see the effectiveness of the BCSE method. These concepts of statistical technique are illustrated and tested in this thesis. Finally, since correct connectivity is critical in system operations, topology estimation is expected to become a standard Energy Management System (EMS) function. Hence, two types algorithm are presented for detection and identification of topology error in BCSE. The first approach uses the idea that when the switch status changes, it will affect the measurements. The second approach is based on changing the on/off status of branches one after the other and performing a state estimation in each case. The effectiveness of the proposed approaches is demonstrated. In addition, topology detection results obtained by the two proposed methods are also compared. For testing the revised BCSE, a reduced version of the IEEE 34 node radial test feeder is used. The simulation platform used in this study is developed using C language on Microsoft Visual Studio .NET 2003.
Date: 2009-08-09
Degree: MS
Discipline: Electrical Engineering

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