Using graph theory to resolve state estimator issues faced by deregulated power systems

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Title: Using graph theory to resolve state estimator issues faced by deregulated power systems
Author: Lei, Jiansheng
Abstract: Power industry is undergoing a transition from the traditional regulated environment to the competitive power market . To have a reliable state estimator (SE ) in the power market environment , two major challenges are emerging , i .e . to keep SE running reliably even under a contingency and to run SE over a grid with extremely large size . The objective of this dissertation is to use graph theory to address the above two challenges . To keep SE running reliably under a contingency , a novel topological approach is first proposed to identify critical measurements and examine network observability under a contingency . To advance the classical topological observability analysis , a new concept of contingency observability graph (COG ) is introduced and it is proven that a power system network maintains its observability under a contingency if and only if its COG satisfies some conditions . As an application of COG , a two -stage heuristic topological approach is further developed based on the new concept of qualified COG (QCOG ) to minimize the number of measurements and RTUs under the constraint that the system remains observable under any single contingency . To overcome the disadvantages of existing SE over extremely large networks , a textured distributed state estimator (DSE ) , which consists of the off -line textured architecture design and the on -line textured computation , is proposed based on COG and a new concept of Bus Credibility Index (BCI ) . The textured DSE is non -recursive , asynchronous and avoids central controlling node . Numerical tests verify that the performance of the new textured DSE algorithm improves greatly compared with existing DSE algorithms in respect of bad data detection and identification . Furthermore , the software implementation for DSE is formulated as an information integration problem over regional power markets , and is very challenging because of its size and complexity . A new concept of semantic knowledge warehouse (SKW ) , together with the proposed concepts of semantic reasoning software component (SRSC ) and deduction credibility , is developed to implement such an information integration system .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1292
Date: 2009-05-15

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Using graph theory to resolve state estimator issues faced by deregulated power systems. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1292 .

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