Utility grid

The motor/generator is modeled as an energy source/sink limited by its specific design capabilities. As a generator, it will absorb all excess power available while holding speed constant (synchronous) as long as it is electrically connected to the utility grid. 

There are more than two billion people without access to electricity, according to the United Nation s Development Program. When night falls in the developing world, 70% of the population are without electrical lighting. Most of these rural areas are too isolated to be connected to a utility grid. 

Cogeneration equipment must be safely connected to the utility grid. Utilities have objected to independent power generation by arguing that safety hazards can exist for their workers if independent systems continue to operate during system-wide blackouts. Such problems can be avoided by the installation of appropriate, standard safety equipment at the cogeneration site. 

Connection to the utility grid provides many advantages to on-site power producers such as reliability improvement and increase of load factor, as well as giving the electric utilities a chance to improve the supply capability. When a fuel cell power plant is used for electric utility applications, the inverter is the interface equipment between the fuel cell and the electrical network. The inverter acts as the voltage and frequency adjuster to the final load. The interface conditions require the following characteristics for the inverter ... 

A load ramp rate of 10 kW/second when connected to the utility grid... 

A load ramp rate of 80 kW/second when operated independently of the utility grid and following the initial ramp up to full power... 

Example of PV solar collectors that supply the home with electricity and by being connected to the utility grid, allows the kWh meter to run "backwards" when more electricity is generated than needed. (Reprinted with permission. Copyright 2007 by Home Power, Inc. http //www. homepower.com.)... 

About 10 MW of utility grid-connected photovoltaic power generation is installed and effectively operating today. 

PV systems using polycrystalline silicon (poly-Si) and amorphous silicon (a-Si) cells have been evaluated [17]. The PV systems considered here are large-scale, centralized systems directly connected to the utility grid and include the balance of system (BOS) with supporting structure, inverter, and DC control device and installed in Tokyo. Assumption for energy conversion efficiencies and PV cell production rates are shown in Table 4. 

The primary switchgear is Powell metal-clad 4-bay switchgear that uses vacuum breakers for generator output and primary utility feed and contains generator and utility protective relays as well as synchronizing controls for generator/utility grid interconnect. 

The SurePower system at the First National Bank of Omaha uses four PC24s and has more than 40% lower C02 emissions than the alternative of using the utility grid with a UPS. 

Obviously, the topping engine approach will cost far more than a simple, once-through system using only a gas burner with air dilution ports. Also, means must be found to use the byproduct electricity in other operations at the same site, or to deliver the power to a utility grid. The critical consideration from a national viewpoint, however, is the fact that this conservation measure will yield much more energy per dollar of capital invested than will comparable investments in new energy supply. 

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