Effects on state estimation of time-skew errors in inter-utility data exchange

Abstract

Inter-utility data exchange poses several unresolved problems. One is the error caused by time skewing of exchanged data. Three manifestations of time skewing, namely, load changes, inter-area interchange changes, and external topology changes, are addressed. The system under study is the IEEE 118-bus system. The system is modified incrementally and solved using a power flow program to simulate different operating states in time. For each operating state the system is divided into three parts, an internal system and two external systems. Selected modified external operating states are combined with the unmodified internal system and solved using a state estimator program, thus simulating exchanging data with various amounts of time skew. The results of load changes and inter-area interchange changes are predictable relationships between errors and changes. Although the actual amount of error would be difficult to determine in actual operation, it could be reliably minimized. The results of topology changes are much less predictable but are considerably easier to detect and may possibly be avoided completely.