Supervisory control for stand-alone photovoltaic systems

This paper proposes a supervisory controller applied to a stand-alone photovoltaic system with a centralized dc bus. The system is comprised of three independently closed-loop controlled converters, whose references and operation modes are defined by the supervisory system. The objective of the proposed supervisory controller is guaranteeing the power balance of the dc bus and to maximize batteries lifetime. A hysteresis strategy using different dc bus voltage level is proposed to avoid unnecessary switching of operation modes and reduce the battery charge/discharge cycles. Experimental results are provided to validate the proposed supervisory control technique.