6 Controlling the Steam Turbogenerator for Watts, VARS, Volts and Frequency Available to Purchase

The following is intended as a brief introduction to the operation of power generation and distribution systems within industrial plants, particularly those with steam turbogenerators. It is especially intended to provide a framework for understanding the principles involved in adjusting turbogenerator excitation so as to regulate bus voltage and/or machine power factor; and to indicate the various constraints on excitation adjustment. From this understanding are defined the principles for using excitation to optimize plant and tie-line power factor in industrial plants. Note that the words “alternator” and “generator” are used synonymously in the following text.

As a brief historical note, Thomas Alva Edison (1846–1931) invented his earliest generator around 1879, as a means for supplying power to the incandescent lights he had recently invented. This generator, an example of which is shown in Figure 6.1, was of the direct current two-wire type and generated power at 240 vDC. The addition of a balance coil enabled a 3-wire system to be provided, operating at 120 vDC.

In his Edison biography, Baldwin (1995) introduces a contemporary of Edison's, Nicola Tesla (1856–1943), who was born in Croatia and studied at the Austrian Polytechnic School in Graz. His vision was of a polyphase alternating current system and, he joined Edison in New York but Edison continued to favor the direct current principle and was hostile to Tesla's approach. A modern version of Tesla's generator, designed to generate alternating current, is shown in Figure 6.2. Tesla's breakthrough came in 1888 when he delivered a lecture to the American Institute of Electrical Engineers on “A New System of Alternate Current Motors and Transformers”. Tesla's lasting contribution to engineering in the United States was the hydroelectric power generation and transmission system located in Niagara Falls, NY.