Power control flexibilities for grid-connected multi-functional photovoltaic inverters

This paper explores the next-generation Photo- Voltaic (PV) system integration issues at a high penetration level, where the grid is becoming more decentralized and vulnerable. Therefore, the PV systems are expected to be more controllable with higher efficiency and higher reliability. Provision of ancillary and intelligent services, like Low Voltage Ride-Through (LVRT), reactive power compensation, and reliability-oriented thermal management/control by PV systems is a key to attain higher utilization of solar energy. Those essential functionalities for the future PV inverters can contribute to reduced cost of energy. To implement the advanced features, a flexible power controller is developed in this paper, which can be configured in the PV inverter and flexibly be changed from one to another. This power control strategy is based on the single-phase PQ theory, and it offers the possibilities to generate appropriate references for the inner current control loop. The references depend on the system conditions and also specific demands from both system operators and customers. Besides, this power control strategy can be implemented in a commercial PV inverter as standardized functions, and also it can be achieved online in a predesigned PV inverter. Case studies with simulations and experiments are provided to verify the effectiveness and flexibilities of the power control strategy.