1 training session on energy equipment electrical systems presentation to energy efficiency guide...
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Training Session on Energy Training Session on Energy EquipmentEquipment
Electrical SystemsElectrical Systems
Presentation to Presentation to
Energy Efficiency Guide for Industry in AsiaEnergy Efficiency Guide for Industry in Asia
Chapter 1Chapter 1
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©© UNEP 2005 UNEP 2005
Training Agenda: ElectricityTraining Agenda: Electricity
IntroductionEl ect ri cal S
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ElectricityElectricity
• 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 ScenarioEl ect ri cal S
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ElectricityElectricity
• 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 ScenarioEl ect ri cal S
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ElectricityElectricity
• 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 ScenarioEl ect ri cal S
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ElectricityElectricity
• 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 & DistributionEl ect ri cal S
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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
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ElectricityElectricity
• 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
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Generation & Distribution
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ElectricityElectricity
• All power stations have generating trans-formers (GTs) that step up the voltage level 132-400 KV
• Conversely, sub-stations have step-down transformers to reduce voltage before distribution
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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
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ElectricityElectricity
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 ElectricityEl ect ri cal S
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Figure: 3-phases of electric system Source: WikipediaThree 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 50-60 times per second
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ElectricityElectricity
• 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 PowerEl ect ri cal S
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Figure: Representation of power triangle Source: OIT
kVA = (KW)2 + (KVAR)2kVA = (KW)2 + (KVAR)2
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©© UNEP 2005 UNEP 2005
ElectricityElectricity
• 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 CorrelationEl ect ri cal S
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El ect ri c it y Figure: Power factor of electric circuit
Figure: Capacitor as kVAR generator
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©© UNEP 2005 UNEP 2005
ElectricityElectricity
• 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 FactorEl ect ri cal S
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Figure: Fixed capacitor banks Source: Ecatalog
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©© UNEP 2005 UNEP 2005
ElectricityElectricity
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 FactorEl ect ri cal S
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ElectricityElectricity
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 FactorEl ect ri cal S
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ElectricityElectricity
• The goal of peak load management is to reduce the maximum electricity demand to lower the electricity costs
Electrical Load ManagementEl ect ri cal S
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Figure: Daily load curve of an engineering industry
KV
A
Hours
• A load curve is useful for integrated load management by predicting patterns of drawl, peaks and valleys in demand
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ElectricityElectricity
• 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 MechanismEl ect ri cal S
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ElectricityElectricity
Peak Load Management StrategiesEl ect ri cal S
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Tab
le: P
eak
load
man
agem
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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.
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©© UNEP 2005 UNEP 2005
ElectricityElectricity
Peak Load Management StrategiesEl ect ri cal S
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• 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
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ElectricityElectricity
• 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
TransformerEl ect ri cal S
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• The number of turns on the 2nd coil (connected to the load) to the turns on the 1st coil (connected to the power source) is the turn’s ratio
Figure: 3 phase core&coil assembly of a transformer Source: Kuhlman
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ElectricityElectricity
Types of transformerEl ect ri cal S
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Table: Classification of transformers
Criteria Types Remark
Based on Input voltage
Step Up Transforms LV to HV
Step Down Transforms HV to LV
Based on OperationPower 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 LocationOutdoor
Located outside on a concrete structure or iron pole structure
Indoor Located inside a shed on concrete structure
Based on Connection
Three PhaseInput & output supply are of three phases (R/Y/B) with or without neutral
Single Phase Input & output supply are of single phase
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ElectricityElectricity
• 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 & EfficiencyEl ect ri cal S
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Figure: Transformer loss vs. % loading
PTOTAL = PNO-LOAD+ (% Load/100)2 x PLOAD
PTOTAL = PNO-LOAD+ (Load KVA/Rated KVA)2 x PLOAD
PTOTAL = PNO-LOAD+ (% Load/100)2 x PLOAD
PTOTAL = PNO-LOAD+ (Load KVA/Rated KVA)2 x PLOAD
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Training Session on Energy Training Session on Energy EquipmentEquipment
Electrical SystemsElectrical Systems
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FOR YOUR ATTENTIONFOR YOUR ATTENTION
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