Nodal admittance modeling of three-phase step-voltage regulators and their applications

This paper presents the nodal admittance modeling of three-phase step-voltage regulators (VRs) and their applications in distribution networks with distributed energy resources. Starting from a review regarding conventional VR primitive models, compact nodal admittance models of VRs with different connection types are deduced. As this new nodal admittance modeling explains the voltage-current relationship of a given VR, the VR is treated as a component in a steady-state system. In other words, it is easy to build an Ybus matrix for networks including VRs, and the Ybus matrix can be utilized for all steady-state analyses. Using the nodal admittance modeling, the procedures for building an Ybus matrix and controlling VRs in a steady-state analysis are described. The computer simulation of VRs is carried out using an IEEE Test Feeder, and the voltage control on certain destination nodes is analyzed. The simulation results show that the proposed modeling of VRs is accurate and effective for the steady-state analysis including the voltage control of VRs. This paper will be applied to educational and (or) practical purposes in modeling and analyzing distribution networks of existing VRs.