Flexible Active Power Control of Distributed Photovoltaic Systems With Integrated Battery Using Series Converter Configurations

Abstract

Flexible active power control (FAPC) is becoming mandatory for PV systems, which is to limit/reserve the PV power below certain constraints as commanded, including the power ramp-rate control (PRRC), power limiting control (PLC), and power reserve control (PRC). In practice, energy storage (ES) such as batteries can be adopted to reduce the PV energy discarding in such cases. On the other hand, concerning the system overall cost, single-stage series power converter configurations are becoming attractive. Such configurations bring more flexibilities by integrating PV systems and batteries. However, the implementation of FAPC functions in series power converter configurations has not been systematically investigated. To fill this gap, the PRRC, PLC, and PRC strategies for series-PV-battery systems are developed in this article. With the proposed strategies, the power ramp-rate/limiting/reserve constraints are maintained by the coordinated control of individual converters. The reserved power is then distributed among all converters depending on the available power of individual PV converters, battery power, and state-of-charge (SoC) conditions. Experimental tests performed on a 1.6-kW system have validated the effectiveness of the proposed solution.