Date of Award

Fall 2006

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Electrical and Computer Engineering

First Advisor

Brown, Ronald H.

Second Advisor

Corliss, George F.

Third Advisor

Povinelli, Richard J.

Abstract

Natural gas is a combustible hydrocarbon composed primarily of methane and accounts for roughly 25% of the total United States energy consumption. There are over 68 million natural gas customers in the US. Natural gas customers are divided into five categories: this thesis focuses on detecting faulty meters for commercial and industrial customers. A natural gas Local Distribution Company (LDC) supplies natural gas to its customers. For this service, the LDC bills the customers at specified intervals. In this study, we detect meter anomalies in the customer data so that the LDC can bill their customers properly. Outlier detection methods such as the 'formula" edit rule and the Hampel identifier are used to identify outliers in the customer data. These outlier detection methods work well for normally distributed data. Outlier detection methods are implemented in mathematical models. We have developed methods to identify anomalies (outliers) in non-normal distributions. In addition, we are applying these concepts to a novel field, natural gas meter readings. We fit the data to a model and look at the residuals for points that are not predicted well by the model. The residual error distribution is asymmetric. That suggests that we apply outlier detection separately to high and low residuals. Outliers are found in the tails, and the tails of our residual distributions are very thick, measured by their kurtoses, compared with a normal distribution. The procedures are applied to an initial data set of 615 meter identifiers (IDs) and generalized to the fulI data set of 3800+ meter IDs. The results are discussed for both outlier detection methods (the 3'1 edit rule and the 'model fitting' exercise) that are used in the study.

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