This paper proposes a hierarchical reactive power regulation system for distribution systems with photovoltaics (PV) connected. The proposed approach includes both central control level and local control level for decisions involving optimal reactive power compensation and dynamic control of reactive power regulation, respectively. Through local control level, based on the PV inverter controllers and central control level compensation command, the overvoltage and voltage variation problems can be highly relieved. In addition to possible reductions in PV generation curtailment, the grid voltage can also be well regulated with minimal line loss via the proposed PV system operation strategies. Accordingly, added value for PV systems is created, conferring win-win solutions for both PV system owners and utilities. Numerical results tested on a practical Taipower company distribution system verified the proposed approach. Copyright © 2015 John Wiley & Sons, Ltd.

The proposed hierarchical control strategies include central control level (CCL) and local control level to obtain optimal operation point and deal with dynamic problems, respectively. A comprehensive optimization algorithm is proposed for CCL. The photovoltaics static compensator dynamic model and control algorithms coordinated with the CCL are proposed as the local control level. The photovoltaics power curtailment to relive the overvoltage can be greatly reduced without any additional energy storage system. The voltage deviation, line loss, and CO2 emission are also decreased.