Simplified power flow modeling approach considering on-load tap changers

Abstract

This paper presents a simplified modeling approach for power flow equations considering on-load tap-changers (OLTCs). The modeling approach consists of only four active and reactive nodal power injections and line power flows equations, and treats the elements of Ybus admittance matrix as constant parameters. The transformer tap ratios are only included in the simplified four equations as control variables, and hence not included in the Ybus matrix. This modeling approach reduces significantly the total number of variables and thus improves the computational time performance. The proposed approach is applicable for any system that does not have tap changing transformers connected in two adjacent buses, or multiple tap changing transformers connected to one bus.