CHAP 1, Lecture 1-A Fundamental's of Power System.ppt
- 1. 1 Chapter One Fundamentals of power system
- 2. 2 1.1 Introduction to Power System Power System is a network of high tension wires/cables by which the generated Electrical power is transmitted and distributed throughout a region. Power System consists of the following main components: Generation System- Energy Conversion Methods Transmission System- Ultra-high, Extra-high, High and Medium Voltage levels Distribution System- Low voltage levels The Load or Energy sink- Residential, Commercial and Industrial loads 1. Fundamentals
- 3. 3 Types of Energy Conversion Methods/Generation Systems: 1. non- conventional (renewable energy sources ) are sources that are continuously replenished by natural processes. PV System, Solar Thermal, Hydropower, Wind Power, Geothermal, Biomass (Renewable conversion systems) 2. Conventional (non-renewable energy sources ) Are sources that are not continuously refilled by natural processes •Diesel Generator, Gas Turbine, Steam Turbine, Coal power plant, Nuclear power (Conventional systems) 1.Generation System Power System main components
- 4. 4 2. Transmission Systems: This component of the power system transmits the bulk electrical energy from generation stations where it is produced to the main load centres. The transmission system is composed of: • Step-up and Step-down substations • Transmission lines 3.Distribution Systems The distribution system gives out the energy from the medium voltage substations to customers’ location. It is composed of: • Medium Voltage (MV) lines (33kV, 15 kV) • MV/LV transformer substations (33/15/ kV to 400/380/220 V) • Distribution lines (33/15 kV, 380 V 3-phase and 220 v single phase) 4. Load or Energy Sink: Load is the end equipment of the power system where the transmitted electrical energy is converted to other forms of useful energy. Cont’d
- 5. 5 The Ethiopian Electric Power Corporation
- 7. 7 • In early days, there was a little demand for electrical energy so that small power stations were built to supply lighting and heating loads. • However, the widespread use of electrical energy by modern civilization has necessitated producing bulk electrical energy economically and efficiently. • The increased demand of electrical energy can be met by building big power stations at favorable places where fuel (coal or gas) or water energy is available in abundance. This has shifted the site of power stations to places quite away from the consumers centers. • The electrical energy produced at the power stations has to be supplied to the consumers. There is a large network of conductors between the power station and the consumers. This network can be broadly divided into two parts viz., transmission and distribution.
- 8. Non-Conventional Energy Sources Renewable energy sources also called non-conventional energy, are sources that are continuously refilled by natural processes. A renewable energy system converts the energy found in - sunlight - wind - falling-water - sea-waves - geothermal heat or - biomass
- 9. Solar Energy Solar energy can be utilized trough two different routs Solar thermal rout. Solar thermal route uses the sun's heat to produce hot water or air, cook food, drying materials etc. Solar electric rout(Photovoltaic) rout. Solar photovoltaic uses sun’s heat to produce directly electricity for the applications such as; lighting home and building, running motors, pumps, electric appliances, and lighting.
- 10. Solar Electricity Generation Solar Photovoltaic (PV): Photovoltaic is the technical term for solar electric. Photo means "light" and voltaic means "electric". PV cells are usually made of silicon, an element that naturally releases electrons when exposed to light. Amount of electrons released from silicon cells depend upon intensity of light incident on it. The silicon cell is covered with a grid of metal that directs the electrons to flow in a path to create an electric current. This current is guided into a wire that is connected to a battery or DC appliance.
- 11. 11 Solar Photovoltaic (PV): Solar Photovoltaic Array
- 14. 14 Wind Power The wind is a free, clean, and inexhaustible energy source. It has served humankind well for many centuries by propelling ships and driving wind turbines to grind grain and pump water. Denmark was the first country to use wind for generation of electricity. One of the most critical features of wind generation is the variability of wind. Wind speeds vary with time of day, time of year, height above ground, and location on the earth’s surface. Wind energy is basically harnessing of wind power to produce electricity. The kinetic energy of the wind is converted to electrical energy.
- 15. 15 Wind Energy Technology 1. Horizontal-axis turbines, in which the axis of rotation is horizontal with respect to the ground (and roughly parallel to the wind stream.) 2. Vertical-axis wind turbines, in which the axis of rotation is vertical with respect to the ground (and roughly perpendicular to the wind stream),
- 16. Bio Energy/Biomass Energy Biomass is a renewable energy resource derived from the carbonaceous waste of various human and natural activities. It is derived from numerous sources, including the by-products from the wood industry, agricultural crops, raw material from the forest, household wastes etc.
- 17. 17 Hydro-power 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 early generation of electricity from about 1880 often derived from hydro-turbines, and the capacity of total worldwide installations has grown at about 5% per year since. Hydro-power now accounts for about 20% of world’s electric generation. Output depends on rainfall and the landscape.
- 18. 18 Hydropower Generation The term hydro-power is usually restricted to the generation of shaft power from falling water. The power is then used for direct mechanical purposes or, more frequently, for generating electricity.
- 19. 19
- 21. 21 Tidal Energy • Tidal electricity generation involves the construction of a bombardment across an estuary to block the incoming and outgoing tide. The head of water is then used to drive turbines to generate electricity from the elevated water in the basin as in hydroelectric dams.
- 22. Geothermal Energy The temperature of the ground or groundwater a few feet beneath the Earth’s surface remains relatively constant throughout the year, even though the outdoor air temperature may fluctuate greatly with the change of seasons. At a depth of approximately six feet, for example, the temperature of soil in most of the world’s regions remains stable between 45º and 70°. This is why well water drawn from below ground tastes so cool even on the hottest summer days. Utilizes the Earth’s inner heated rocks to heat water that reaches these areas through seismic faults. This water is turned to steam then captured to operate steam-powered generators.
- 23. 23 Geothermal Potentials in Ethiopia Aloto Langano (Ziway) Tendaho (Afar)
- 24. Conventional Energy sources Is a stocks of energy Not continuously refilled using natural process. They are: Fossil fuels - Coal, Oil, & Natural Gas Nuclear fuel –
- 25. Natural gas A natural gas is a mixture of different gases the main ingredient is Methane, a natural compound that is made from the decay of plant and animal remains. Nuclear Fission Splitting uranium atoms produces a great deal of heat energy that is processed into electrical energy in nuclear plants.
- 26. 26 Structure of a Power System
- 27. 27 Large Consumers Medium and small Consumers Generator-3 Step-down Transformer Step-down Transformer Step-up Transformer Step-up Transformer Generator-1 Generator-2 Transmission System Generation System Distribution System 11,11.5 kV 132,230 kV 400,500 kV 15,20 kV 15,20 kV 400,500 kV 400,500 kV 132,230 kV 66,45 kV 66,45 kV 33,15 kV 400/220 V 33/15 kV Single line diagram of a Power System Structure Cont’d
- 28. 28 • The conveyance of electric power from a power station to consumers’ premises is known as an electric supply system. • It consists of three principal components viz., the power station, the transmission lines and the distribution system. • Electric power is produced at the power stations which are located at favorable places, generally quite away from the consumers. It is then transmitted over large distances to load centers with the help of conductors known as transmission lines. • Finally, it is distributed to a large number of small and big consumers through a distribution network. • The electric supply system can be broadly classified into (i) DC. or AC. system (ii) overhead or underground system. Electric Supply System
- 29. 29 ,
- 30. 30 AC and DC TRAMSMISSION Systems
- 31. 31 Introduction
- 34. 34 Main Elements of Transmission Line
- 35. 35 Main Elements of Transmission Line
- 36. 36
- 39. 39 HVDC Transmission System • Investment Cost comparison of HVAC/HVDC
- 40. 40 Difference between AC & DC Quantities
- 41. 41 Comparison of AC and DC transmission • The electric power can be transmitted either by means of DC. or AC. Each system has its own merits and demerits. It is, therefore, desirable to discuss the technical advantages and disadvantages of the two systems for transmission of electric power. DC transmission. • For some years past, the transmission of electric power by DC. has been receiving the active consideration of engineers due to its numerous advantages. Advantages. • (i) It requires only two conductors as compared to three for AC. transmission. • (ii) There is no inductance, capacitance, phase displacement and surge problems in DC. transmission. 41
- 42. 42 • (iii) Due to the absence of inductance, the voltage drop in a DC. transmission line is less than the AC. line for the same load and same sending end voltage. For this reason, a DC. transmission line has better voltage regulation. • (iv) There is no skin effect in a DC. system. Therefore, entire cross- section of the line conductor is utilized. • (v) For the same working voltage, the potential stress on the insulation is less .Therefore, a DC. line requires less insulation. • (vi) A DC. line has less corona loss and reduced interference with communication circuits. • (vii) The high voltage DC. transmission is free from the dielectric losses, particularly in the case of cables. • (viii) In DC. transmission, there are no stability problems and synchronizing difficulties. Cont’d Advantages
- 43. 43 (i) Electric power cannot be generated at high DC. voltage due to commutation problems. • (ii) The DC. voltage cannot be stepped up for transmission of power at high voltages. • (iii) The DC. switches and circuit breakers have their own limitations. A.C. transmission. • Now-a-days, electrical energy is almost exclusively generated, transmitted and distributed in the form of a.c. Advantages • (i) The power can be generated at high voltages. • (ii) The maintenance of AC. sub-stations is easy and cheaper. • (iii) The AC. voltage can be stepped up or stepped down by transformers with ease and efficiency. Disadvantages
- 44. 44 • This permits to transmit power at high voltages and distribute it at safe potentials. Disadvantages • (i) An AC. line requires more copper than a DC. line. • (ii) The construction of AC. transmission line is more complicated than a DC. transmission line. • (iii) Due to skin effect in the AC. system, the effective resistance of the line is increased. • (iv) An AC. line has capacitance. Therefore, there is a continuous loss of power due to charging current even when the line is open.
- 45. 45 Comparison of Sources Power based on Merits and Demerits Merits of Coal Thermal Plant Coal is cheap and available in abundance at present. It is a time tested process, so no experimentation is required. Less space required as compared to Hydro based station and less hazardous than Nuclear power plant. Less initial cost as compared to other conventional process of power generation.
- 46. 46 Cont’d… Demerits of Coal Thermal plant Calorific value (Kcal/Kg) of Indian coal is very low and large ash content. Huge volume of ash is produced daily and it’s disposal is burning issue today. Atmospheric pollution is very high. Transportation of coal to plant and transmission of generated power to load centre involves large expenses.
- 47. 47 Cont’d… Advantages of Nuclear Power Generation Less quantity of fuel for generation of given amount of energy compared to other sources. High reliability, Efficient and less running cost. Disadvantages of Nuclear Power Generation Fuel is expensive and not available in abundance everywhere. High capital cost. Maintenance cost is very high. Nuclear waste disposal is a great problem.
- 48. 48 Cont’d… Advantages of Hydro Power Generation Once a dam is constructed, electricity can be produced at a constant rate If electricity is not needed, the sluice gates can be shut, stopping electricity generation The build up of water in the lake means that energy can be stored until needed, when the water is released to produce electricity. The lake's water can be used for irrigation purposes. Hydropower is fueled by water, so it's a clean fuel source. Hydropower doesn't pollute the air like power plants that burn fossil fuels, such as coal, oil or natural gas.
- 49. 49 Cont’d… Disadvantages of Hydro Power Plant Dams are extremely expensive to build and must be built to a very high standard. People living in villages and towns that are in the valley to be flooded, must move out. Hydro power plants can be impacted by drought. When water is not available, the hydro power plants can't produce electricity.
- 50. 50 Cont’d… Advantages of Wind Energy System The wind is free and with modern technology it can be captured efficiently. Once the wind turbine is built the energy it produces, does not cause green house gases or other pollutants. Remote areas that are not connected to the electricity power grid can use wind turbines to produce their own supply. Wind turbines are available in a range of sizes which means a vast range of people and businesses can use them. Single households to small towns and villages can make good use of range of wind turbines available today.
- 51. 51 Cont’d… Disadvantages of Wind Power The strength of the wind is not constant and it varies from zero to storm force. This means that wind turbines do not produce the same amount of electricity all the time. There will be times when they produce no electricity at all. Wind turbines are noisy.
- 52. 52 Cont’d… Advantages of Solar Energy Systems After initial investment, all the electricity produced is free. Incentives and rebates from government and utility companies offset the initial investment. Clean, renewable energy source. No transmission costs for stand alone systems. Virtually no maintenance and no recurring costs Ideal for remote locations that cannot be tied to the grid
- 53. 53 Cont’d… Disadvantages of Solar Energy High initial cost to purchase solar panel system A relatively large area is required to install a solar system The highest efficiency is dependent on full sun exposure No electricity can be produced at night, and reduced production on cloudy/rainy days
- 54. 54 • THE END!!!