Transcript Electricity
Training Session on Energy Equipment Electricity Presentation from the “Energy Efficiency Guide for Industry in Asia” www.energyefficiencyasia.org 1 © UNEP 2006 Training Agenda: Electricity • Future electricity scenario • Generation & distribution • Phase of electricity • Active and reactive power • Power factor correction • Electrical load management • Electrical billing mechanisms • Transformers 2 © UNEP 2006 Electricity General Electricity Scenario • Development can be measured by a nation’s electricity consumption • Electricity usage is divided into: a) Industrial b) Commercial and residential c) Agriculture and irrigation • Electricity important input for industry 3 © UNEP 2006 Electricity General Electricity Scenario International Energy Agency predicts for 2030: • 78% of population in developing countries has access to electricity • 1.4 billion people no access • 665 billion US$ needed to overcome this 4 © UNEP 2006 Electricity General Electricity Scenario • How can electricity supply shortage be solved? a) Renovation and modernization of plants, transmission and distribution systems b) Demand side management with the utilization of energy efficiency technologies c) Awareness raising among energy users 5 © UNEP 2006 Electricity Generation & Distribution • Electricity generation: fossil fuels and uranium • Renewable energy is growing World electricity generation by energy Renewable 21% Nuclear 16% Fossil fuels 63% (US Energy Information Administration, 2004) 6 © UNEP 2006 Electricity Generation & Distribution Transmission system Power plant Distribution system Generator GT 10.6 KV 220 KV Distribution Step down transformer 7 © UNEP 2006 Electricity Generation & Distribution • AC generators (“alternators”) generate electricity • Electricity generated at 9-13 KV • Power generated from 67.5 to 1000 MW • Power stations: generating transformers (GTs) to increase voltage to 132-400 KV • Substations: step-down transformers to reduce voltage before distribution 8 © UNEP 2006 Electricity Generation & Distribution Benefits of high voltage transmission • Less voltage drop: good voltage regulation • Less power loss: high transmission efficiency • Smaller conductor: lower costs 9 © UNEP 2006 Electricity Phase of Electricity Single phase AC circuit: • Two wires connected to electricity source • Direction of current changes many times per second 3-phases of an electric system (Wikipedia contributors, 2005) Three phase systems: • 3 lines with electricity from 3 circuits • One neutral line • 3 waveforms offset in time: 50-60 cycles/second 10 © UNEP 2006 Electricity Phase of Electricity Star connection Delta connection 11 © UNEP 2006 Electricity Active and Reactive Power • Active power (kW): real power used • Reactive power (kVAR): virtual power that determines load/demand • Utility pays for total power (kVA) kVA = (KW)2 + (KVAR)2 Source: OIT 12 © UNEP 2006 Electricity Power Factor Correlation 13 Figure: Power factor of electric circuit © UNEP 2006 Electricity PF Correction: Capacitors • kVAR demand should be as low as possible for the same kW output Figure: Capacitor as kVAR generator 14 © UNEP 2006 Electricity PF Correction: Capacitors • Act as reactive power generators • Reduce reactive power • Reduce total power generated by the utilities Figure: Fixed capacitor banks Source: Ecatalog 15 © UNEP 2006 Electricity PF Correction: Capacitors Advantages for company: • One off investment for capacitor • Reduced electricity costs: • Total demand reduced • No penalty charges • Reduced distribution losses • Increased voltage level at load end, improved motor performance 16 © UNEP 2006 Electricity PF Correction: Capacitors Advantages for utility: • Reduced reactive component of network • Reduced total current in the system from the source end • Reduced I2R power losses • Reduced need to install additional distribution network capacity 17 © UNEP 2006 Electricity Electrical Load Management • Goal: reduce maximum electricity demand to lower the electricity costs KVA • Load curve predicts patterns in demand Daily load curve of an engineering industry (National Productivity Council, India) 18 Hours © UNEP 2006 Electricity Electrical Load Management Strategies to manage peak load demand: • Shift non-critical / non-continuous process loads to off-peak time • Shed non-essential loads during peak time • Operate in-house generation or diesel generator (dg) sets during peak time • Operate AC units during off-peak times and utilize cool thermal storage • Install power factor correction equipment 19 © UNEP 2006 Electricity Electricity Billing Mechanism • Energy charges • Actual charges based on active power • Charge based on apparent power • Maximum demand charges • Based on maximum demand registered • Penalty for peak load 20 © UNEP 2006 Electricity Electricity Billing Mechanism • Power factor penalty or bonus • Fuel costs • Electricity duty charges • Meter rentals • Lighting & fan power consumption • Time of Day (TOD) rates 21 © UNEP 2006 Electricity Electricity Billing Mechanism Utility uses trivector meter for measurement during billing cycle (usually month): • Maximum demand • Active energy in kWh • Reactive energy in kVArh • Apparent energy in kVAh 22 © UNEP 2006 Electricity Electricity Billing Mechanism • Demand measured in time intervals • Maximum demand is highest reading • Customer charged on highest maximum demand value! 23 A Typical Demand Curve (National Productivity Council) © UNEP 2006 Electricity Transformer • Static electrical device that transforms electrical energy from one voltage level to another • Two or more coils linked magnetically but electrically insulated • Figure 12: A view of a transformer (Indiamart.com) Turns Ratio: turns on 2nd coil (connected to load) turns on 1st coil (connected to power source) 24 © UNEP 2006 Electricity Transformer types Transformers are classified based on: • Input voltage • Operation • Location • Connection 25 © UNEP 2006 Electricity Transformer Losses & Efficiency PTOTAL = PNO-LOAD+ (% Load/100)2 x PLOAD PTOTAL = PNO-LOAD+ (Load KVA/Rated KVA)2 x PLOAD Transformer loss versus percent loading (BEE, 2004) • Transformer losses: constant and variable • Best efficiency: load where constant loss = 26 variable loss © UNEP 2006 Electricity Electricity Formulae • Resistance (Ohm) • Power factor • Voltage (Volts) • Efficiency • Reactance • Transformer ratio • Impedance • • Real power (Watt) Voltage drop in a line • Star connection • Delta connection • • Reactive power Apparent power 27 © UNEP 2006 Training Session on Energy Equipment Electricity THANK YOU FOR YOUR ATTENTION 28 © UNEP GERIAP Disclaimer and References • This PowerPoint training session was prepared as part of the project “Greenhouse Gas Emission Reduction from Industry in Asia and the Pacific” (GERIAP). While reasonable efforts have been made to ensure that the contents of this publication are factually correct and properly referenced, UNEP does not accept responsibility for the accuracy or completeness of the contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the contents of this publication. © UNEP, 2006. • The GERIAP project was funded by the Swedish International Development Cooperation Agency (Sida) • Full references are included in the textbook chapter that is available on www.energyefficiencyasia.org 29 © UNEP 2006