Module 1 : Introduction
Lecture 1 : Modern Power Systems
Objectives
In this lecture you will learn the following
Evolution of power systems: significant milestones.
Structure of a bulk power system network.
What is a synchronous grid? Why is grid frequency standardised?
Evolution
Electrical Technology was founded on the remarkable discovery by Faraday that a changing magnetic flux creates an electric
field. Out of that discovery, grew the largest and most complex engineering achievement of man: the electric power system.
Indeed, life without electricity is now unimaginable. Electric power systems form the basic infrastructure of a country. Even as
we read this, electrical energy is being produced at rates in excess of hundreds of giga-watts (1 GW = 1,000,000,000 W).
Giant rotors spinning at speeds up to 3000 rotations per minute bring us the energy stored in the potential energy of water, or
in fossil fuels. Yet we notice electricity only when the lights go out!
While the basic features of the electrical power system have remained practically unchanged in the past century, there are
some significant milestones in the evolution of electrical power systems:
First complete DC power system built by Edison (1882): Incandescent lamps supplied by steam driven DC generators
(electrical cable system at 110V). 59 customers spread over an approximate area with 1.5 km radius.
Development of transformers led to supersession of DC systems by AC systems (why?).
Nikola Tesla - polyphase induction motors: led to development of AC 3 phase systems.
Interconnection of systems led to standardization of frequency (why?), 60 Hz in North America and 50 Hz in most
other countries. Use of higher and higher voltage levels (up to 1000 kV line-line rms AC). Standardization of voltage
levels.
Development of Mercury Arc Valves, and subsequently thyristors led to high voltage dc transmission (HVDC): DC
transmission suited for very long distance bulk transmission and underwater cable links. First commercial DC link in
1954.
Several new developments : Gas turbines, static excitation systems, fast acting circuit breakers, microprocessor based
relaying, use of communication technologies etc.
Need for better utilisation and operation of AC transmission systems by use of high power electronic converters
suggested. Several such converters are now in operation.
Structure
Present day power systems are characterised by:
AC generation (3 phase synchronous machines using hydro, fossil and nuclear as primary energy sources)
AC transmission (a limited number of DC transmission links are present in some systems)
3 phase AC utilization (some loads are single phase, but they are usually distributed equally in all phases
to obtain a balanced system)
Lecture 1 : Modern Power Systems
Objectives
In this lecture you will learn the following
Evolution of power systems: significant milestones.
Structure of a bulk power system network.
What is a synchronous grid? Why is grid frequency standardised?
Evolution
Electrical Technology was founded on the remarkable discovery by Faraday that a changing magnetic flux creates an electric
field. Out of that discovery, grew the largest and most complex engineering achievement of man: the electric power system.
Indeed, life without electricity is now unimaginable. Electric power systems form the basic infrastructure of a country. Even as
we read this, electrical energy is being produced at rates in excess of hundreds of giga-watts (1 GW = 1,000,000,000 W).
Giant rotors spinning at speeds up to 3000 rotations per minute bring us the energy stored in the potential energy of water, or
in fossil fuels. Yet we notice electricity only when the lights go out!
While the basic features of the electrical power system have remained practically unchanged in the past century, there are
some significant milestones in the evolution of electrical power systems:
First complete DC power system built by Edison (1882): Incandescent lamps supplied by steam driven DC generators
(electrical cable system at 110V). 59 customers spread over an approximate area with 1.5 km radius.
Development of transformers led to supersession of DC systems by AC systems (why?).
Nikola Tesla - polyphase induction motors: led to development of AC 3 phase systems.
Interconnection of systems led to standardization of frequency (why?), 60 Hz in North America and 50 Hz in most
other countries. Use of higher and higher voltage levels (up to 1000 kV line-line rms AC). Standardization of voltage
levels.
Development of Mercury Arc Valves, and subsequently thyristors led to high voltage dc transmission (HVDC): DC
transmission suited for very long distance bulk transmission and underwater cable links. First commercial DC link in
1954.
Several new developments : Gas turbines, static excitation systems, fast acting circuit breakers, microprocessor based
relaying, use of communication technologies etc.
Need for better utilisation and operation of AC transmission systems by use of high power electronic converters
suggested. Several such converters are now in operation.
Structure
Present day power systems are characterised by:
AC generation (3 phase synchronous machines using hydro, fossil and nuclear as primary energy sources)
AC transmission (a limited number of DC transmission links are present in some systems)
3 phase AC utilization (some loads are single phase, but they are usually distributed equally in all phases
to obtain a balanced system)
