Lecture 1 Introduction to Power Systems Dr. Ali Al-Awami

Power Power: Instantaneous consumption of energy Power Unit: Watt (W) Installed Saudi generation capacity is about 50 GW (about 1.8 kW per person) Maximum load of the Eastern Province of Saudi Arabia is about 12.5 GW

Energy Energy: Integration of power over time; energy is what people really want from a power system Saudi annual electric energy consumption is about 212 billion kWh (about 7,862 kWh per person, which means on average we each use 0.79 kW of power continuously) Energy Units Joule= 1 Watt-second (J) kWh– Kilowatthour (3.6 x 10 6 J)

Power System Examples Power grid: can range from quite small, such as an island, to one covering half the continent – there are several major “interconnected” ac power systems in Saudi Arabia, each operating at 60 Hz ac. Many other countries, such as all other GCC countries, operate at 50 Hz.

Power System Examples Saudi Power Grid

Power System Examples Airplanes and Spaceships: reduction in weight is primary consideration; frequency is 400 Hz. Ships and submarines Electric vehicles Battery operated portable systems

Sources of Energy - US Source: EIA Energy Outlook 2011 CO2 Emissions (millions of metric tons) Petroleum: 2598 Natural Gas: 1198 Coal: 2115 About 86% Fossil Fuels In 2009, US got about 0.75% of its energy from wind and only 0.04% from solar (PV and solar thermal)

Global Warming and the Power Grid, What is Known: CO2 in Air is Rising Source: Value was about 280 ppm in 1800; in 2011 it is 394 ppm

As Has Been Worldwide Temperature Source: / Baseline is 1961 to 1990 mean

Electricity Market Models Vertical Monopoly: One company owns everything: generation, transmission, and distribution Deregulated Market: Several companies compete.

Vertical Monopolies Within a particular geographic market, the electric utility had an exclusive franchise Generation Transmission Distribution Customer Service In return for this exclusive franchise, the utility had the obligation to serve all existing and future customers at rates determined jointly by utility and regulators It was a “cost plus” business

Utility Restructuring (Deregulation) Driven by significant regional variations in electric rates (in some parts of the world, like the US and Europe) Goal of restructuring is to reduce rates through the introduction of competition Eventual goal is to allow consumers to choose their electricity supplier. This is similar to the telecommunication market restructuring. Instead of a single service provider, multiple providers compete (STC, Mobily, Zain, etc.).

Power System History 12

History o William Gilbert, English ( ) – Was the first to use the term electric Derivation from the Greek word for amber. The word amber itself was derived from the Arabic word عنبر. 13 o Alessandro Volta, Italian ( ) –Invented the first battery in –Today we use the unit Volt for the electric potential.

History o André-Marie Ampère, French ( ) – Understood the relation between electric currents and magnetism. Essential for motors, generators, and transformers. – Ampere is used as a unit for electric current. 14 o George Simon Ohm, German ( ) –Related electric current to the electromotive force (Ohm's law). –The cornerstone for circuit analysis and designs. –Ohm is the unit for resistance.

History o Michael Faraday, British ( ) – His work set the foundations of all electromechanical theories. – The unit of capacitance (farad) is named after him. 15

History o Antonio Pacinotti, Italian ( ) – invented a device that had two sets of windings wrapped around a common core. – This was the basis for the transformers we use today. – Westinghouse further developed the transformer and had several early models Gaulard and Gibbs transformer developed in 1883 Stanley transformer developed in – Meanwhile, Ferranti was developing his own. This created fights over patenting! 16

Ferranti’s Transformer 17

History o John Hopkins, British – Patented the three-phase system for generation and distribution in

Thomas Edison ( ) o American o Had patents! – his first patent was granted at age 21 – his last one was at age 83. – What is Edison’s average patenting rate per month?! – 1.5 patents/month!! – The most important of which is… 19

Nikola Tesla ( ) o Serbian o 800 patents… only!! o Moved from Serbia to the US in o Worked for Edison in his lab as a research assistant. o He left Edison’s lab after a salary dispute! 20

AC vs. DC 21

Should it be AC or DC? o Edison system was 100V DC o In September 1882, his plant in New York started operation – the world's first commercial electric lighting power station. 22

Problems With Low Voltage o For the same power, the lower the voltage, the higher is the current. P: Power V: Voltage I: Current 23

Problems With Low Voltage o High currents require large cross section wires – Expensive copper wires – Heavy wires that cannot be easily mounted on transmission towers – Customers voltage is substantially reduced at heavy loading conditions 24

Line Voltage Drop 25

Wire Resistance 26 o To reduce the wire resistance A should be increased. However, bigger cross section wires are – more expensive – heavier and would require poles to be placed at shorter spans.

Edison’s Options o To have several small cross-section wires feeding areas with high demands. – Expensive solution; more wires for long miles. o To place electrical generators at every neighborhood. – Impractical and expensive solution. – Might be the choice of the future grid, though! o To increase the voltage – Best solution, but the technology to increase the voltage of the dc system was not available then. 27

Tesla’s Solution 28 o Tesla knew the problem was related to the low voltage (100 V) Edison was using in his dc system. – For same power, increasing the supply voltage reduces the current. – Hence the voltage drop across the wire could be reduced. o However, adjusting the voltage of dc systems was beyond the technology at that time.

Here Comes the AC! o Main Advantage of AC: – The voltage of AC systems can be changed by transformers. o How about DC? – The transformers cannot change the DC voltage. 29

30 Tesla’s Solution (AC system)

So, who won the debate? Tesla did 31