Chapter

The Basics of Electricity

May 2015

DOI:10.1002/9781119040934.ch2

In book: Wind Energy Essentials: Societal, Economic, and Environmental Impacts (pp.34-47)

Authors:

Electrical energy is the generation or use of electric power over a period of time expressed in kilowatt-hours (kWh) or megawatt-hours (MWh). The key difference between energy and power is that power is an instantaneous measurement at a single point in time, whereas energy is measured over some increment of time, such as an hour, a day, or a year. The types of electrical equipment include the following: generator, wind generator or wind turbine, transformer, distribution lines, transmission lines and substation. The types of companies within the electric sector are vertically integrated utility, retail electricity provider, generation company, independent power projects (IPPs), transmission service provider (TSP or transco), and transmission and distribution company. Some of the most frequently asked questions about the electric grid and how wind energy interacts with it, along with answers to these questions are provided at the end of this chapter.

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Article

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Increased Wind Energy Yield and Grid Utilisation with Continuous Feed-In Management

June 2017 · Energies

This paper presents a study to assess how wind turbines could increase their energy yield when their grid connection point is not strong enough for the rated power. It is state of the art that in such situations grid operators impose feed-in management on the affected wind turbines, i.e., the maximum power is limited. For this study a 5 MW wind turbine is introduced in a small grid that has only ... [Show full abstract] limited power transfer capabilities to the upstream power system. Simulations of one particular day are conducted with the electric load, the temperature, and the wind speed as measured on that day. This simulation is conducted twice: once with the 5 MW wind turbine controlled with conventional feed-in management, and a second time when its power is controlled flexibly, i.e., with continuous feed-in management. The results of these two simulations are compared in terms of grid performance, and in terms of mechanical stress on the 5 MW wind turbine. Finally, the conclusion can be drawn that continuous feed-in management is clearly superior to conventional feed-in management. It exhibits much better performance in the grid in terms of energy yield and also in terms of constancy of voltage and temperature of grid equipment. Although it causes somewhat more frequent stress for the wind turbine, the maximum stress level is not increased.

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Study of transmission and protection elements for wind energy generating systems. Volume 1

January 1970

Results are reported of a study at Cornell University on transmission, distribution, and protection systems for large wind-energy generators (WEG) connected to an electric utility grid. Configurations for wind farms on flat terrain, mountain-peak clusters, and installations along a ridge were examined. Computer studies of load-flow and short-circuit behavior confirmed the technical feasibility of ... [Show full abstract] the proposed systems. Realistic unit costs for the projected transmission and protection schemes range from

109 to

317 per Kw, depending upon choice of configuration and distance from the grid. Cost of protective equipment is found to be a major factor in most cases, tending to be equal or greater than transmission line costs when the WEG units are located five miles or less from the grid. Several alternatives are suggested for future study.