1) Siting Hydroelectric plants are located in geographic areas where they will make economic use of hydraulic energy sources. Hydraulic energy is available wherever there is a flow of liquid and accumulated head. Head represents potential energy and is the vertical distance through which the fluid falls in the energy conversion process. The majority of sites utilize the head developed by freshwater; however, other liquids such as saltwater and treated sewage have been utilized. The siting of a prospective hydroelectric plant requires careful evaluation of technical, economic, environmental, and social factors. A significant portion of the project cost may be required for mitigation of environmental effects on fish and wildlife and relocation of infrastructure and population from flooded areas. 2) Hydroelectric Plant Schemes There are three main types of hydroelectric plant arrangements, classified according to the method of controlling the hydraulic flow at the site: 1. ...
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Hydroelectric power generation involves the storage of a hydraulic fluid, water, conversion of the hydraulic (potential) energy of the fluid into mechanical (kinetic) energy in a hydraulic turbine, and conversion of the mechanical energy to electrical energy in an electric generator. The first hydroelectric power plants came into service in the 1880s and now comprise approximately 20% (875 GW) of the worlds installed generation capacity (World Energy Council, 2010). Hydroelectricity is an important source of renewable energy and provides significant flexibility in base loading, peaking, and energy storage applications. While initial capital costs are high, the inherent simplicity of hydroelectric plants, coupled with their low operating and maintenance costs, long service life, and high reliability, makes them a very cost-effective and flexible source of electricity generation. Especially valuable is their operating characteristic of fast response for start-up, loading, unloading,...
Successfully practice electrical engineering to serve state and regional industries, government agencies, or national and international industries. Work professionally in one or more of the following areas: analog electronics, digital electronics, communication systems, signal processing, control systems, and computer-based systems. Achieve personal and professional success with awareness and commitment to their ethical and social responsibilities, both as individuals and in team environments. Maintain and improve their technical competence through lifelong learning, including entering and succeeding in an advanced degree program in a field such as engineering, science, or business. Electrical Engineering Student Outcomes Student outcomes are statements that describe what students are expected to know and are able to do by the time of graduation, the achievement of which indicates that the student is equipped to achieve the program objectives. The generalized outcomes for ...
A current-carrying coil produces a magnetic field that links its own turns. If the current in the coil changes the amount of magnetic flux linking the coil changes and, by Faraday’s law, an emf is produced in the coil. This emf is called a self-induced emf. Let the coil have N turns. Assume that the same amount of magnetic flux F links each turn of the coil. The net flux linking the coil is then NF. This net flux is proportional to the magnetic field, which, in turn, is proportional to the current I in the coil. Thus we can write NF µ I. This proportionality can be turned into an equation by introducing a constant. Call this constant L, the self-inductance (or simply inductance) of the coil: As with mutual inductance, the unit of self-inductance is the henry. The self-induced emf can now be calculated using Faraday’s law: The above formula is the emf due to self-induction. Example Find the formula for the self-inductance of a solenoid of N turns, length l, and cross-s...
Suppose we hook up an AC generator to a solenoid so that the wire in the solenoid carries AC. Call this solenoid the primary coil. Next place a second solenoid connected to an AC voltmeter near the primary coil so that it is coaxial with the primary coil. Call this second solenoid the secondary coil. As shown in figure. The alternating current in the primary coil produces an alternating magnetic field whose lines of flux link the secondary coil (like thread passing through the eye of a needle). Hence the secondary coil encloses a changing magnetic field. By Faraday’s law of induction this changing magnetic flux induces an emf in the secondary coil. This effect in which changing current in one circuit induces an emf in another circuit is called mutual induction. Let the primary coil have N1 turns and the secondary coil have N 2 turns. Assume that the same amount of magnetic flux F 2 from the primary coil links each turn of the secondary coil. The net flux linking the secondary...
Since the equivalent circuit contains two winding resistances and a core-loss resistance then power is lost as heating energy inside the transformer. Hence the conversion of power through the transformer cannot be 100%, a small loss of efficiency occurs. This is usually less than about 2% for power transformers. Assume all resistances and reactances are referred to the secondary winding. The efficiency can be expressed as, Where cosØ is the power factor of the load Pc is the core-loss Is is the secondary current Vs is the secondary voltage Es is the secondary emf. This formula applies to single-phase transformers, or to one phase of a three-phase transformer.
A single-phase power system transformer consists basically of two windings wound onto an iron core. The iron core concentrates the flux and restricts it to a defined path. It also creates the maximum possible amount of flux for a given excitation. In order to maximize the mutual coupling the two windings are wound concentrically on to the same part of the iron core. Figure 6.1 shows the typical winding arrangement of a single-phase transformer. This is called shell-type construction. Not all the flux created by one winding couples with the other winding. Furthermore the flux which does not couple both windings does not flow completely round the iron core, some of it flows in the air close to the windings. The common flux in the iron circuit is called the mutual or magnetizing flux. The flux that escapes into the air and does not couple the windings is called the leakage flux. One winding is referred to as the primary winding and is connected to the source of supply voltage. The second ...