An External System Equivalent for on-line Steady-State Generator Outage Simulation

This paper describes an external system equivalent for on-line generator outage simulation. The equivalent models the steady- state MW response of the external system after primary speed control actions. The proposed method is an extension to the Ward equivalent. Starting with the frequency response characteristics of the individual units and loads in the external system, equivalent frequency response characteristics for each boundary bus have been developed. These equivalent frequency response characteristics model not only the total in-rush, but also the distribution among the individual tie lines. In addition to the data required for branch outage simulations the incremental speed regulations and rated powers of all external units on the line are assumed to be known. No real-time measurement data from the external control areas are required. The suggested equivalent has been verified by off-line simulations of 10 severe generator outages in three European 380/220 kV networks.