113 Distribution System Economics

While this section is not intended to be a comprehensive treatment of distribution system economics, it may be instructive to the reader to understand some fundamental economic issues associated with distribution system planning and operations. Transmission and distribution system equipment must be sized to accommodate the maximum load to which the equipment will be subjected. Because average demand is usually much less than maximum demand (as shown in Figure 11.4), there is normally a lot of unused capacity in the system. Because of load diversity characteristics, this is usually more prevalent closer to the load.

When capacity needs to be added, expansion must come in increments. This incremental expansion can be quite large compared to the rate of growth. For example, if there is a 30 MVA transformer serving a community that becomes overloaded, it is a very large investment to replace it with a 45 MVA transformer. Other options include adding a second transformer in parallel, or other methods of reconfiguring load. However, all of these options can be quite expensive.

Planning how to accommodate this capacity expansion requires accurate load forecasting. Often, where load growth occurs has little correlation with existing load. For example, if a utility predicts annual growth of 4%, most of this will likely occur in outlying areas with new construction rather than in the areas in which load is currently served. Therefore, siting and sizing substation capacity, and the feeders and other distribution infrastructure, becomes a difficult planning exercise. It is anticipated that distributed resources will increasingly enhance the ability of planners to cope with this growth without investing in infrastructure upgrades that have a likelihood of becoming stranded assets if the planning assumptions are wrong.

Solar Stirling Engine Basics Explained

Solar Stirling Engine Basics Explained

The solar Stirling engine is progressively becoming a viable alternative to solar panels for its higher efficiency. Stirling engines might be the best way to harvest the power provided by the sun. This is an easy-to-understand explanation of how Stirling engines work, the different types, and why they are more efficient than steam engines.

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