Distributed generation system is an effective way to integrate renewable energy resources like photovoltaic (PV). With the increasing penetration of PV, the power quality of the utility is challenged. Aim to the power quality enhancement of grid-tied PV systems, the power fluctuation at DC bus and harmonic at AC bus are addressed. An improved PV interface combined energy storage (ES) is proposed to handle these issues. The hybrid ES including batteries and supercapacitors are utilized to suppress the power fluctuation of PV. An adaptive-filter-based algorithm is used to detect the harmonic current of local load, to enhance the power quality of the PV-ES system. In order to manage the PV-ES system, a hierarchical control is employed. A power dispatching control is used to set the power references of PV, batteries, and supercapacitors. Local controller of converters are presented to track the power reference. In such a way that, the PV-ES system can be much more grid-friendly and schedulable. Simulated results by using PSCAD/EMTDC are achieved to confirm the validity and effectiveness of the proposed models and control schemes.
This work is jointly supported by National Key Basic Research Program of China (“973 Program”) (Grant 2012CB215200), Fundamental Research Funds for the Central Universities (Grant 106112015CDJXY150005, CDJZR12150074) and Science and Technology Project of SGCC (Grant SGHADK00PJJS1500060).