Source matching on micro-grid fed through parallel acting CRIGs connected at common DC-link with small capacity battery support

This paper proposes scheduling of induction generators on a DC microgrid system fed by multiple cage-rotor induction generators (CRIGs) to attain regulated voltage with minimal battery support. The capacity of each generator is selected such that next bigger generation unit is double that of previous i.e. the ratio 1∶2∶4∶8‥, which provides easy control of load-generation matching, duly supported by a small rated battery storage system for compensating real power fluctuations. Thus the entire generator group inherently caters the real power demand of the variable consumer load connected at one end of the offgrid DC micro-grid (μG). Each CRIG has excitation capacitor and voltage source converter (VSC) support for meeting the dynamic reactive power demand henceforth referred as DG. The DC bus is made common for each DG for transfer of real power through its own inverter. The control scheme schedules the generation unit till the consumer load falls lesser than the capacity of combined generation, the battery then tends to charge for the short span or deliver the differential power which remains after scheduling of appropriate capacity CRIG taken out from cluster of generators in the μG. This operation reduces the storage capacity required to maintain the frequency at PCC. The proposed scheme is better, efficient, and cost effective. It also requires lesser control hardware with optimal power extracting capacity from the source. The scheme is particularly effective for conserving the available head in pumped storage based system, especially in summers. The proposed scheme is simulated in Matlab/ Power System Blockset and simulation results gauges the system effectiveness.