Decoupled voltage stability assessment of distribution networks using synchrophasors

This paper presents a real-time voltage stability assessment in distribution networks (DNs) capable of separating the effects of the transmission and distribution network by using synchronized phasor measurements. The method aims to assist transmission and distribution system operators to quantify the need of their services in different parts of the DN in order to provide adequate voltage support to their specific stakeholders. The method uses data from phasor measurement units (PMUs) to estimate models for both DN and transmission network (TN). A Thévenin equivalent model is estimated for the TN and a T-model for the DN. By applying the superposition theorem on these two models, the contribution of each network to the overall system voltage stability can be distinguished at a specific bus (equipped with a PMU). The method has been validated by a hardware-in-the-loop setup which consists an OPAL-RT real-time simulator and three PMUs.