Incorporating instrument transformer errors to voltage stability assessment

Reactive compensation of transmission makes the PV curve flatter and could potential lead to loss of sufficient discrimination between the normal operating and critical voltage. This can make it difficult to distinguish critical voltage from the normal metered operating voltages during highly stressed transmission operation. Further, instrument transformers are known to contain both magnitude and phase errors which can impact on the evaluation of the PV analysis and potential false updates of real-time system operating condition. This paper assesses the potential impacts that metering errors could have on voltage stability analysis. Theoretical formulation and simulations are conducted using a two-bus network and WSCC 9-bus system with various levels of reactive compensation.