Modern day power systems are complicated networks with number of generating stations and load centers being interconnected through power transmission lines. An electric power system has three separate components – power generation, power transmission and power distribution. Electric power is generated by synchronous alternators that are usually driven either by steam or hydro turbines. Based on the type of fuel used for the generation of electric power, the generating stations are categorized as thermal, hydro, nuclear etc. These generating stations are remotely located. Therefore the electric power generated at any such station has to be transmitted over a long distance to consumers that are usually large cities or towns. Besides that, fossil fuel price is drastically increasing due to the global economic and limited resource and also it is found that producing electricity with conventional fossil fuel will lead to the environment pollution.
Throughout the last century and in the present, the size of generating plants has been increasing. A new trend however is emerging currently, in which significantly smaller sized generating units are being connected at the distribution level. Some of the factors that contribute to this trend are listed below.
– Greenhouse gas issues have become very significant in many countries to consider dispersed energy sources such as solar, wind and wave that operate with smaller sized units.
– Local generating units using gas micro turbines are becoming more economical when the transmission and distribution overheads are taken into account. Fuel cells are still more expensive but have been showing great promise for low cost reliable small size generation units.
– Even though solar cells currently require a very large area and substantial investments, they can be used for power in large office buildings during business hours.
– The move to open competitive markets in electricity has increased the uncertainties of supply. In response to this uncertainty of central supply there was a massive increase in demand for back-up generation with the possibility of generation back into the grid when conditions suited