Converting a Commercial-Consumer-Fed, Ring Distribution System into a Diesel-Solar Hybrid Microgrid: Technical Feasibility

Complex distribution networks like ring or meshed networks are applied for commercial and industrial cities demanding reliable power supply. Diesel generators are connected to the network to maintain system reliability under emergency states. With increasing penetration of non-dispatchable, rooftop solar-PV, proper planning is required to maintain system stability and reliability. Commercial and industrial cities do not follow the conventional diurnal load patterns, but presents load patterns similar to the diurnal generation curve of solar-PV. Thus, by introducing solar-PV, required diesel generation capacity can be reduced. Also, the system reliability and stability can be improved if the system is operated as a microgrid. The ability of forming ring-radial connected hybrid-microgrid based on an existing network for a commercial city with peak day-time loading is evaluated. Small-signal stability analysis reveals that, even with 100% solar-PV, the islanded microgrid in normal state is stable under different diesel generation integration topologies tested. The system becomes unstable due to small perturbations under the N-l emergency operation in some topologies. This study allowed identification of the proper diesel generation integration topology for the proposed microgrid.