I. Introduction
In future active distribution grids, the nature of increasing dynamics and uncertain behavior of the distributed generations (DGs) and new actors at the demand side call for a real-time reliable monitoring system as a fundamental element to meet new control needs [1]–[3]. Currently, distribution grids lack in sufficient metering infrastructure. Because of cost reasons, a full deployment of the required measurement devices throughout the distribution grids is not feasible. Therefore, a reliable and accurate awareness of system conditions must be achieved via distribution system state estimation (DSSE) incorporating all available measurement data.