Analyzing effect of bad measurement data on load flow and state estimation in power system

Accurate results of load flow become imperative for monitoring and control of emerging power system. Measurements used for load flow and state estimation are important for economical operation, optimal power flow, contingency analysis and security of a system. Measurements may be imperfect or erroneous due to problems in the communication channel, measuring instruments, A/D converters etc. Erroneous measurements can lead to divergence of load flow and/or erroneous load flow results. Hence, authors propose state estimation as an alternative to load flow in case of erroneous measurement data. In the paper presented, effect of bad measurement data on load flow has been verified on single machine two bus system and WSCC 3-generator 9-bus multi-machine system for stable and transient conditions. Using chi-square bad data detection algorithm, detected bad data are removed and states are estimated with remaining measurements. After removal of bad measurement data, use of accurate estimation of states is proposed instead of load flow results.