Fuel cells: A utilities perspective

In order for fuel cells to become a valuable resource for the utility the basic operating principles and grid interactions must first be understood. Extensive literature is available that addresses the requirements of DG operation and interconnection, but the effect fuel cells would have on a distribution level circuit are less known. Developed here is a basic "what if" scenario that examines the types of benefits a utility could recognize if various size fuel cells were distributed along an existing distribution circuit. This paper studies the affect fuel cells or other distributed generation (DG) would have on a "typical" Southern California Edison (SCE) 12 kV circuit. Chosen to study was an actual SCE circuit located east of Los Angeles. It was selected because it represents the type of circuit SCE feels DG would be most helpful. The simulation will provide a general understanding of fuel cell impacts on utility circuits, and specifically will determine the size (MW) and placement of fuel cells that allow the utility to realize the necessary generation and VAR support benefits. The Main Tasks were to: Select a circuit in SCE's territory to study, Model the loads associated with the selected circuit, Develop equivalent circuits and models of the distribution circuits, Conduct simulations, Identify the impact fuel cells, up to a total of 3 MW, have on the circuit, identify optimum placement, and identify the benefit of VAR support supplied by the fuel cell power electronics. Several assumptions were used to simplify the calculations and allow for accurate and easy to understand results. The simulation was a three-wire three-phase balanced circuit, with no automated switches. In addition the circuit simulated was an actual SCE circuit of radial design that was not networked; the loads used in the calculations were estimated. The circuit itself represents a "Typical" 12 kV distribution circuit with mostly residential loads, where the topology for the circuit was extracted from the circuit maps and F1M overhead and underground maps, and the simulation includes the capacitor banks already present on the circuit. As a result of running the circuit simulations several "Rule of Thumb" Observations can be made to help SCE better understand how fuel cells would affect line voltage, line losses, and current flows. This will help SCE guide industry leaders down a path that leads to the greatest benefits for utilities, technology leaders, and most of all the customers.