1 Training Session on Energy Equipment Electrical Systems Presentation to Energy Efficiency Guide for Industry in Asia Chapter 1 © UNEP GERIAP Electrical Systems/ Electricity

2 © UNEP 2005 Training Agenda: Electricity Introduction Electrical Systems/ Electricity

3 © UNEP 2005 Electricity 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 is one of the most important inputs for the industrial sector General Electricity Scenario Electrical Systems/ Electricity

4 © UNEP 2005 Electricity Electrification in developing countries will reach 78% of the population by 2030 (World Energy Outlook) Electricity supply must increase by 1,000 tWh to satisfy the world’s electricity demand by the year 2030 (World Energy Outlook) The world’s poorest and remote will gain more electricity access (World Energy Outlook) General Electricity Scenario Electrical Systems/ Electricity

5 © UNEP 2005 Electricity How can the challenge of the growing gap between electricity demand and supply be solved? a)Renovation and modernization of plants, transmission and distribution systems b)Demand side management c)Awareness raising among energy users General Electricity Scenario Electrical Systems/ Electricity

6 © UNEP 2005 Electricity Most of the world's electricity is generated using non-renewable energy sources such as fossil fuels (coal, gas and oil) and radioactive substances such as uranium Generation & Distribution Electrical Systems/ Electricity Figure: World electricity generation Source: EIA Renewable 21% Nuclear 16% Fossil fuels 63% World electricity generation by energy Renewable energy techno- logies is widely researched to make it better and cheaper

7 © UNEP 2005 Electricity Electricity is generally generated by AC generators known as “alternators” in thermal, hydro or nuclear plants Electricity is typically generated at 9-13 KV and the power generated is in the range of 67.5 MW, 110 MW, 220 MW, 500 MW Generated power is transmitted to the user end through a transmission & distribution network Electrical Systems/ Electricity Generation & Distribution

8 © UNEP 2005 Electricity All power stations have generating trans- formers (GTs) that step up the voltage level KV Conversely, sub-stations have step-down transformers to reduce voltage before distribution Electrical Systems/ Electricity Generation & Distribution Generator 10.6 KV GT 220 KV Step down transformer Distribution Power plant Transmission system Distribution system Figure: Single line diagram of generation and transmission system

9 © UNEP 2005 Electricity A single phase AC circuit: Has two wires connected to the electricity source The direction of the current changes many times per second Phase of Electricity Electrical Systems/ Electricity Figure: 3-phases of electric system Source: Wikipedia Three phase systems: Have 3 waveforms that are that are 2/3π radians (120 degrees,1/3 of a cycle) offset in time The cycle in the figure above will repeat itself times per second

10 © UNEP 2005 Electricity Active power (kW) is the real power used by any load to perform a task Reactive power (kVAR) is virtual in nature and decides the load/demand on an electrical system The utility has to pay for the total power (kVA) Active and Reactive Power Electrical Systems/ Electricity Figure: Representation of power triangle Source: OIT kVA =  (KW) 2 + (KVAR) 2

11 © UNEP 2005 Electricity Power factor is the ratio of active power (kW) to the apparent power (kVA) = Cosine of the angle The undesirable component (kVAR) demand should be as low as possible for the same kW output Power Factor Correlation Electrical Systems/ Electricity Figure: Power factor of electric circuit Figure: Capacitor as kVAR generator

12 © UNEP 2005 Electricity Correction capacitors act as reactive power generators and accomplish kW of work This reduces the amount of total power that has to be generated by the utilities Improving Power Factor Electrical Systems/ Electricity Figure: Fixed capacitor banks Source: Ecatalog

13 © UNEP 2005 Electricity Advantages with capacitor addition: Reactive component of the network is reduced and also the total current in the system from the source end I2R power losses are reduced in the system because of reduction in current. Voltage level at the load end is increased kVA loading on the source generators as also on the transformers and lines up to the capacitors reduces giving capacity relief Improving Power Factor Electrical Systems/ Electricity

14 © UNEP 2005 Electricity Cost benefits of power factor improvement: Reduced kVA (maximum demand) charges in utility bill Reduced distribution losses (kWH) within the plant network Better voltage at motor terminals and improved performance of motors A high power factor eliminates penalty charges imposed when operating with a low power factor Improving Power Factor Electrical Systems/ Electricity

15 © UNEP 2005 Electricity The goal of peak load management is to reduce the maximum electricity demand to lower the electricity costs Electrical Load Management Electrical Systems/ Electricity Figure: Daily load curve of an engineering industry KVA Hours A load curve is useful for integrated load management by predicting patterns of drawl, peaks and valleys in demand

16 © UNEP 2005 Electricity Maximum Demand Charges Energy Charges Fuel cost adjustment charges Electricity duty charges Meter rentals Lighting and fan power consumption Time Of Day (TOD) rates Penalty for exceeding contract demand Electricity Billing Mechanism Electrical Systems/ Electricity

17 © UNEP 2005 Electricity Peak Load Management Strategies Electrical Systems/ Electricity Table: Peak load management strategies 1) Shifting Non-Critical and Non-Continuous Process Loads to Off-Peak time Rescheduling of large electric loads and equipment operations in different shifts, these can be planned and implemented to minimize the simultaneous maximum demand. 2) Shedding of Non- Essential Loads during Peak Time It is possible to install direct demand monitoring systems, which will switch off non-essential loads when a preset demand is reached. 3) Operating In-House Generation or Diesel Generator (DG) Sets during Peak Time Connect the DG sets for durations when demand reaches the peak value in order to reduce the load demand to a considerable extent and minimize the demand charges. 4) Operating Air Conditioning units during off-peak times and utilizing cool thermal storage Reduce the maximum demand by building up storage capacity of products/ materials, water, chilled water / hot water, using electricity during off peak periods. 5) Installation of Power Factor Correction Equipments The maximum demand can also be reduced at the plant level by using capacitor banks and maintaining the optimum power factor.

18 © UNEP 2005 Electricity Peak Load Management Strategies Electrical Systems/ Electricity The demand varies from time to time Maximum demand is the time integrated demand over the predefined recording cycle Trend analysis can help identify key areas for electricity cost reduction Figure: Typical demand curve

19 © UNEP 2005 Electricity A static electrical device that transforms electrical energy from one voltage level to another Consists of two or more coils that are electrically insulated but linked magnetically Transformer Electrical Systems/ Electricity The number of turns on the 2nd coil (connected to the load) to the turns on the 1 st coil (connected to the power source) is the turn’s ratio Figure: 3 phase core&coil assembly of a transformer Source: Kuhlman

20 © UNEP 2005 Electricity Types of transformer Electrical Systems/ Electricity Table: Classification of transformers CriteriaTypesRemark Based on Input voltage Step Up Transforms LV to HV Step Down Transforms HV to LV Based on Operation Power Transformer Located at Power Stations to Step up the voltage & handles large power. Typical voltage ratings are 400 kV, 220kV, 132KV, 66 kV, 33kV etc. Distribution Transformer Located at Sub-Stations of a distribution network and handles low power. Typical voltage ratings are 11kV, 6.6 kV, 3.3 kV, 440V, 230V etc. Instrument Transformer Used for measuring high voltage and current in measuring instruments Based on Location Outdoor Located outside on a concrete structure or iron pole structure Indoor Located inside a shed on concrete structure Based on Connection Three Phase Input & output supply are of three phases (R/Y/B) with or without neutral Single Phase Input & output supply are of single phase

21 © UNEP 2005 Electricity The transformer losses are due to constant and variable losses The best efficiency occurs at the load where constant loss and variable loss are equal Transformer Losses & Efficiency Electrical Systems/ Electricity Figure: Transformer loss vs. % loading P TOTAL = P NO-LOAD + (% Load/100) 2 x P LOAD P TOTAL = P NO-LOAD + (Load KVA/Rated KVA) 2 x P LOAD P TOTAL = P NO-LOAD + (% Load/100) 2 x P LOAD P TOTAL = P NO-LOAD + (Load KVA/Rated KVA) 2 x P LOAD

22 Training Session on Energy Equipment Electrical Systems THANK YOU FOR YOUR ATTENTION © UNEP GERIAP Electrical Systems/ Fans & Blowers