Protection Algorithm for Photovoltaic Based Distribution System

Distributed Energy Resources (DERs) are small size power generating sources installed to electricity requirement of small scale electricity customers. Zero emission and renewable feature make them as popular choice for future energy demand particularly in peak demand in public utility network. The design of a protection scheme for their safe operation during utility tied connection and islanded mode of operation is an essential operational requirement. As the density of the photovoltaic based distributed energy resources increase in the distribution systems, the fault current contribution from these resources becomes comparable with the fault current from utility substation. Additionally the fault infeed for PV system is close to their loading limits and this possesses a great challenge for design of protection schemes. In this research article, a voltage and current based protection algorithm is presented which can accurately discriminate between the fault currents seen during utility tied and islanded mode of operation. The proposed algorithm is implemented in IEEE 9 bus reference network.