EXTERNAL DATA EXCHANGE ISSUES FOR STATE ESTIMATION IN POWER SYSTEMS

Kai Yin Kenny Poon

Nowadays, large interconnections comprise several reliability coordinators and many balancing authorities. Each reliability coordinator and balancing authority has its own control center with its own state estimator for monitoring the area under its control. The portion of the network outside a utility's control area is known as the external network and the modeling of the external system is required for a state estimator monitoring an internal system. In reality, each of these reliability coordinators has a unique external model which causes the largest errors in the real time models for maintaining situation awareness. In recent years, there has been a renewed interest in the situation awareness for the entire interconnection as a result of recent cascading blackouts which affected an area not covered by any one control center. The feasibility of multi-area power system state estimation has already been studied from an algorithmic viewpoint and most of these studies have been in the investigation of state estimation schemes involving independent state estimators for each control area and a central coordinator. The actual implementation of a state estimator, however, depends on various factors, such as the time skew of data, the accuracy of the network database, the availability of raw data versus state-estimated data, and sensitive issues regarding the proprietary nature of the data. These issues are studied in this dissertation to determine the data exchange requirements for minimizing the errors in state estimation Specifically, the effects of various levels of data exchange between the external model and the state estimator on state estimation accuracy are studied. This includes investigating the retention of more detailed external models than the present day practice of only retaining equivalents at the boundary buses. The differences between exchanging SCADA data versus state estimated data are also investigated and the importance of correct topology knowledge during state estimation is investigated. Finally, the effects of data exchange during state estimation on ensuing contingency analysis accuracy are also studied. All the studies are performed on two test bed systems. The first one is the IEEE-118 bus system and the second one is the 1648 bus system.

EXTERNAL DATA EXCHANGE ISSUES FOR STATE ESTIMATION IN POWER SYSTEMS

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