EE 207: Fundamentals of Electrical Power Systems Chapter 2 Power Systems: An Overview

Introduction Support Components Main Components

Supply of Electricity

Electrical Systems Demand Electricity energy cannot be stored. Generate electricity based on demand. Total power drawn by consumer fluctuates depends on the time of day and seasons. Demand Curve Plot each demand of electricity by consumer daily/annually

Demand Curve

Load Duration Curve 3 types of load Base load Intermediate loads Has to be fed 100% of the time. Intermediate loads Have to be fed <100% of the time. Peak load May occur 0.1% of the time.

Load Duration Curve Plot the duration of each demand on annual based. 100% : 8760hrs

Load Duration Curve Base-power stations Intermediate-power stations Deliver full power at all times Nuclear, coal-fired, hydro stations,… Intermediate-power stations Respond relatively quickly to changes in demand Usually by adding/removing generating unit Hydropower stations Peak-power stations Deliver power for brief intervals during the day Put into service very quickly Equipped with prime movers that can be started up in a few minutes Diesel, pumped-storage turbines, gas turbines etc.

Reduce the voltage 33kV,11kV Power System Diagram Generation Step-up transformer (↑ voltage,↓current) Grid System (500kV, 275kV, 132kV, 66kV) Reduce the voltage 33kV,11kV Transmission Distribution Loads 3 phase - 415 V, single phase - 240 V

Power System AROUND TOWN & RESIDENTIAL AREA - Underground distribution to individual premises is at 415 volts and 240 volts. HOUSE - Overhead distribution to individual houses is at 240 volts. LIGHT INDUSTRY - Most small factories receive their electricity at 11,000 volts HEAVY INDUSTRY - Some have direct connections to the transmission at 132,000 volts. POWER STATION- Generator output at 11,000/20,000 volts is stepped up by transformer to 132,000 275,000 and 500,000 volts for transmission. TRANSMISSION - Transmission is mainly at 132,000 275,000 and 500,000 volts

High voltages of 500kV, 275kV, 132kV are used for transmitting electricity over the grid system

A transformer in a large sub-station reduces the voltage to 33kV, 22kV,11kV

Supplies to rural communities are often reduced from 11kV to domestic voltages (415/240V) by pole mounted transformers.

Generation At power generating station (generating voltage)  11 – 20kV and frequency of 50 Hz Transform to higher voltage (transmission voltage)  132kV, 275kV and 500kV Transform to lower voltage (distribution voltage)  33kV or 11kV

Worldwide Commercial Energy Production Since energy is always required to do useful work, the production of energy is one of the most important efforts made by society. Fossil fuels are derived from organic material produced from biomass derived from the process of photosynthesis many millions of years ago. This organic material that was built up in geological deposits over long periods of time are today the primary source of energy for society, accounting for about 79% of all commercial energy in the world. Of the major three fossil fuels (oil, coal and gas), oil is the most important energy source. Oil accounts for 35% of total world energy production. Nuclear makes up 7%. Biomass fuels account for 9.5% of total commercial and energy production. Other renewables such as solar, wind and hydro account for 4.5% of the total. This shows that total renewables (biomass, hydro, etc.) provide 14% of the energy.

Coal The supply of coal in the world is about 10 times greater than oil and gas combined. Much of the coal of the world is located in North and Central America, Asia, and Europe. Coal represents the fossil fuel with the highest reserves relative to the amount presently used. It is likely that coal reserves in the world could supply energy for human use for 200 years at the present consumption rate. Today, oil is the primary energy source throughout the world, as well as one of the primary contributors to political problems. A single country, Saudi Arabia, has about one quarter of the known supplies of oil in the world, over 10% of recoverable oil reserves are in the volatile Mideastern countries. Interestingly, the nations of the world with the largest amounts of all oil are among the most politically troubled. For instance, Saudi Arabian nationals comprised most of those primarily responsible for the destruction of the World Trade Center in the U.S., the country to which Saudi Arabia sends the largest amount of its oil exports. The countries of Iraq, Iran, Kuwait, and Venezuela also do not rank among the most stable economies or governments in the world and they have much of the earth's oil reserves. Natural gas, the third most important fossil fuel, has the largest reserves located in the former U.S.S.R. and the Middle East. Natural gas produced from Canada and internally within the United States is one of the main sources of heating fuel for Seattle. Natural gas is extremely efficient to utilize, but very difficult to store and move.

Oil The supply of coal in the world is about 10 times greater than oil and gas combined. Much of the coal of the world is located in North and Central America, Asia, and Europe. Coal represents the fossil fuel with the highest reserves relative to the amount presently used. It is likely that coal reserves in the world could supply energy for human use for 200 years at the present consumption rate. Today, oil is the primary energy source throughout the world, as well as one of the primary contributors to political problems. A single country, Saudi Arabia, has about one quarter of the known supplies of oil in the world, over 10% of recoverable oil reserves are in the volatile Mideastern countries. Interestingly, the nations of the world with the largest amounts of all oil are among the most politically troubled. For instance, Saudi Arabian nationals comprised most of those primarily responsible for the destruction of the World Trade Center in the U.S., the country to which Saudi Arabia sends the largest amount of its oil exports. The countries of Iraq, Iran, Kuwait, and Venezuela also do not rank among the most stable economies or governments in the world and they have much of the earth's oil reserves. Natural gas, the third most important fossil fuel, has the largest reserves located in the former U.S.S.R. and the Middle East. Natural gas produced from Canada and internally within the United States is one of the main sources of heating fuel for Seattle. Natural gas is extremely efficient to utilize, but very difficult to store and move.

Natural Gas The supply of coal in the world is about 10 times greater than oil and gas combined. Much of the coal of the world is located in North and Central America, Asia, and Europe. Coal represents the fossil fuel with the highest reserves relative to the amount presently used. It is likely that coal reserves in the world could supply energy for human use for 200 years at the present consumption rate. Today, oil is the primary energy source throughout the world, as well as one of the primary contributors to political problems. A single country, Saudi Arabia, has about one quarter of the known supplies of oil in the world, over 10% of recoverable oil reserves are in the volatile Mideastern countries. Interestingly, the nations of the world with the largest amounts of all oil are among the most politically troubled. For instance, Saudi Arabian nationals comprised most of those primarily responsible for the destruction of the World Trade Center in the U.S., the country to which Saudi Arabia sends the largest amount of its oil exports. The countries of Iraq, Iran, Kuwait, and Venezuela also do not rank among the most stable economies or governments in the world and they have much of the earth's oil reserves. Natural gas, the third most important fossil fuel, has the largest reserves located in the former U.S.S.R. and the Middle East. Natural gas produced from Canada and internally within the United States is one of the main sources of heating fuel for Seattle. Natural gas is extremely efficient to utilize, but very difficult to store and move.

Hydro-electricity

Percent of total electricity generation as hydro-electricity

Electricity generation capacity (Ontario, Canada)

Hydro-Québec sources of energy supply (2013)  Other Renewables (2.9%)  Nuclear (0.2%)   Thermal (0.1%)

Generation Capacity in Malaysia Generation capacity of major power producer

Generation Capacity Generation Plant Mix

TNB Power Stations

Hydroelectric Power Plant

Under construction

Coal-fired Power Plant

Combustion Turbine Power Plant

Transmission To ensure the adequacy and reliability of supply that are fundamental needs of modern society. Provides the link between electricity suppliers and electricity consumers. Helps reduce energy prices since generation in other regions which are cheaper can be channeled to customers. Transmission connects regional systems via inter-connectors to encourage cooperation for mutual benefits.

Transmission System Lines/transformers operating at voltages above 100 kV are usually called the transmission system. Consists of Transmission Line and Sub-stations Transmission network of 500kV, 275kV and 132kV known as National Grid.

Transmission Line Components Overhead Lines Cable Underground Cables Submarine Cables Sub-stations

Transmission Line Components Tower support structure Cross-arms Conductors Insulators Earth-wires

Transmission tower                                                                                                     Waist-Type Tower Double Circuit Tower Guyed-V-Tower

Transmission Tower

Overhead Line Conductors

Insulators

Sub-station Size of substation Types of Sub-station Depends on transformer size Types of Sub-station Conventional outdoor Require bigger space GIS (gas insulated switchgear) Less space Outdoor or indoor

Outdoor Sub-station

GIS

Sub-station Components Transformer Circuit Breaker / Switch Gear Isolator Switches Busbar Protection Relay & Control Equipment

Power Transformer

Circuit Breaker Spark gap. In event of a lightning strike on the line, the current can jump the gap between that ball and the protrusion on the tank, and make a path to earth. This prevents overloading the breaker.

Circuit Breaker

Distribution Lines/transformers operating at voltages below 100 kV are usually called the distribution system. Part of the electric utility system between the bulk power source and the customer service entrances (loads).  33kV, 22kV, 11kV, 6.6kV, 415V and 240V

Distribution Sub-station Distribution Intakes (33kV, 22kV) Distribution Substations (22kV, 11kV, 6.6kV) Indoor substation Outdoor substation Pole mounted substation Compact substation Underground substation Transformer capacity 100kVA, 300kVA, 500kVA, 750kVA and 1000kVA

Distribution Intake

Indoor Sub-station

Underground Sub-station

Compact Sub-station

Outdoor Sub-station

Pole-Mounted Sub-station

Distribution Transformer

Distribution Circuit Breaker

Load Types of Load: Residential Commercial Industrial Public Transportation Public Lighting etc.

Residential Load Consist of lighting, radio, TV, refrigerator, kitchen appliances, washing machine and etc. Usually, increases in the evening around 6 p.m. and return to a nominal value around 12 p.m.  

Commercial Load Consists of lighting, air-condition and small appliances. Shops, business premises, schools, universities etc. The load is fairly constant from 9am until 9pm with the exception of any mid-day break.

Industrial Load Mainly consists of motor load, air conditioner, lighting, welding and furnaces etc. It can be divided into small, medium and large category. The nature of industrial load curve will depend on the number of shifts worked in the industry.

Electricity Consumers

National Grid System

Advantages Provide multiple paths between various generation sources and loads Provide for power transfers from one geographic area to another to achieve overall system operating economics Interconnect the bulk power facilities of individual power station/utilities so that they can better withstand major disturbances

Advantages Other advantages: Stability Continuity of service Economy Load sharing Continuity of service Maintenance, breakdown Economy Cheap & efficient

Interconnection Peak lopping; imports during peak load (morning) and export during lower demand (evening) Economic power exchange; export if its price is lower than other and vice versa Help each other during system emergencies/crisis

Load Dispatch Centre (LDC) Objectives: Grid system requires a grid controller/operator system. In order to ensure the supply of energy is safe and reliable.

LDC Function Maintains system stability Achieve minimum operating cost Frequency control Voltage within limits Achieve minimum operating cost Optimize transmission losses Merit order generation maintain spinning reserve requirements co-ordinate generation and transmission maintenance outages Restoration of supply after system fault

Future ASEAN Power Supply Interconnection