1. A NEW DC ANTI-ISLANDING TECHNIQUE OF ELECTROLYTIC
CAPACITOR-LESS PHOTOVOLTAIC INTERFACE IN DC
DISTRIBUTION SYSTEMS
ABSTRACT:
This paper proposes a photovoltaic (PV) generation system interfaced with a dc distribution system.
DC interface allows for the improvement of system efficiency by fully utilizing dc-based renewable sources
and storage devices. In this paper, issues on PV interface for dc distribution systems are discussed for
energy-efficient and reliable system implementation. AC and dc PV interfaces are mathematically analyzed.
In dc distribution, eliminating electrolytic capacitors in PV interfaces improves system reliability, increases
system efficiency, and reduces cost. In addition, this paper proposes a new anti-islanding technique for dc
distribution as a system protection scheme. The operating principle is presented in detail and analysis shows
that the proposed injected current perturbation technique is an effective solution for anti-islanding operation.
A prototype converter features a simple structure with no electrolytic capacitor, which ensures a longer
lifetime of the PV power circuit. Experimental results of the prototype circuit show a maximum efficiency
of 98.1% and a European efficiency of 97.5%. The proposed anti-islanding technique shows fast response to
the islanding condition in less than 0.2s. It also shows that the average maximum power point tracking
efficiency is 99.9% in normal conditions, which verifies the performance of the proposed scheme.