Introduction to Compensation in Power System – For reduction of cost and improved reliability, most of the world’s electric power systems continue to be interconnected. Interconnections take advantage of diversity of loads, availability of sources and fuel price for supplying power to loads at minimum cost and pollution with a required reliability. In a deregulated electric service environment, an effective electric grid is essential to the competitive environment of reliable electric service.
Now-a-days, greater demands have been placed on the transmission network, and these demands will continue to rise because of the increasing number of nonutility generators and greater competition among utilities themselves. It is not easy to acquire new rights of way. Increased demands on transmission, absence of long-term planning, and the need to provide open access to generating companies and customers have resulted in less security and reduced quality of supply.
Compensation in power systems is, therefore, essential to alleviate some of these problems. Series/shunt compensation has been in use for past many years to achieve this objective.
In a power system, given the insignificant electrical storage, the power generation and load must balance at all times. To some extent, the electrical system is self-regulating. If generation is less than load, voltage and frequency drop, and thereby reducing the load. However, there is only a few percent margin for such self-regulation. If voltage is propped up with reactive power support, then load increase with consequent drop in frequency may result in system collapse. Alternatively, if there is inadequate reactive power, the system may have voltage collapse.
This chapter is devoted to the study of various methods of compensating power systems and various types of compensating devices, called compensators, to alleviate the problems of power system outlined above. These compensators can be connected in the system in two ways, in series and in shunt at the line ends (or even in the midpoint).
Apart from the well-known technologies of compensation, the latest technology of Flexible AC Transmission System (FACTS) will be introduced towards the end of the chapter.