Local photovoltaic reactive power controller for increasing active distribution networks hosting capacity

Abstract

The photovoltaic (PV) hosting capacity of active distribution networks is usually restricted by network overvoltage at peak PV generation hours. In the literature, several methodologies are presented to mitigate this problem caused by PVs reactive power regulation. However, the feeder transformer's thermal limit and branch lines loading confine the PVs reactive power capability. This study proposes a fully local reactive power regulation strategy enabling the PV systems to increase the feeder hosting capacity without using communication infrastructure. In the suggested framework, the distribution feeder is partitioned into several zones based on the feeder's electrical bottlenecks from the perspective of lines loading condition. The PV units placed in the vicinity of the electrical bottlenecks are equipped with the proposed local controller to moderate burden on the corresponding bottlenecks. Other PV units support the network voltage using a conventional local voltage-dependent reactive power controller. Consequently, the feeder hosting capacity can be enhanced while equipment loadings remain in their permissible limits. Moreover, the network power loss is decreased due to the local reactive power management. Furthermore, the proposed approach provides superior coordination between the PV systems controller and the transformer feeder tap changing mechanism. The advantages of the proposed approach are demonstrated by simulation results on 33- and 69-node radial and meshed distribution feeders.