An Approach for Deriving a Two‐Machine Dynamic Equivalent of Multimachine Power Systems Using a Memorizing Factor–Based RLS Algorithm

This paper presents a three‐step identification‐based dynamic equivalencing approach for multimachine electric power systems. Viewed from the bus of a local machine, a multimachine power system is modeled as a lossy two‐machine equivalent (LTME) system. The LTME system comprises the local machine, an equivalent transmission line, and an equivalent synchronous machine connected in series. The LTME system parameters are estimated using the simulated time responses of the multimachine system following a disturbance. The required parameters are categorized into two types: electrical parameters (EPs) and mechanical parameters (MPs). The first two steps of the proposed method are formulated as linear recursive least‐squares (RLS) estimation problems. An RLS algorithm with a memorizing factor is then employed in these steps to estimate the LTME system parameters. In the third step, a critical clearing time (CCT)–based method is used to determine appropriate values for the memorizing factors applied in the first two steps. Transient stability studies of power systems can be conducted using the resulting LTME system. The proposed approach is validated on the New England 10‐generator, 39‐bus test system using the classical machine model, and the simulation results are discussed in detail.