ATAR SINGH

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ENERGY AUDIT OF AUXILIARY POWER CONSUMPTION
ATAR SINGH Dy. DIRECTOR NPTI FARIDABAD
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Energy Conservation in PowerUtility

• Power plant produces electrical energy and also
  consumes a substantial amount of energy in the
  form of auxiliary consumption required for
  various plant equipments and services

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Energy Conservation in Power Utility

• Achieved mainly by
• Operating the equipments at maximum
  efficiency and
• Reduction of auxiliary Power consumption

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• The auxiliary power consumption (APC) varies from
  6-14 , depending on Size of plant ,use of TDBFP
  age of plant
• The 500 MW units register the least APC, largely
  due to the incorporation of TDBFP.
• In some of the old 110 MW plants, APC
  consumption of 14 is also observed.
• Energy audit in a vast thermal power station
  (TPS) is better tackled when the thermal
  power plant operations are segregated into
  different sub-areas like
• main plant auxiliaries, draft system
  (consisting of ID/FD/PA fans), feed water
  system consisting of Boiler Fed Pumps
  (BFPs) / Condensate Extraction Pumps (CEPs),
  Circulating Water (CW) system-including
  Cooling Tower (CTs), and off sites (consisting
  of coal handling plants, ash handling plants, air
  compressors, AC plants, station lightings etc.).

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APC Scenario In India

• Auxiliary Power Consumption in Thermal Power
  Plant is major source of energy consumption.
• During the financial year 2007-08 total
  generation by coal plant was 488157.46 MUs with
  PLF 78.75.
• Auxiliary Power Consumption was 8.17.
• If this APC gets reduced only by 0.17 then
  it is equivalent to fresh capacity addition of
  120 MW without any investment.

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• Trombay Station of Tata Power Co. Ltd achieved
  lowest auxiliary power consumption (4.30) in the
  country.

• Among Central Sector Stations, Talcher
• STPS of NTPC achieved the lowest auxiliary
• power consumption (5.34).

• Among State Sector Stations, Chandrapur
• STPS of MAHAGENCO achieved the lowest
• auxiliary power consumption (7.40).

• Among different capacity groups, the lowest
• auxiliary power consumption was 6.13 in 500
• MW group.

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Requirement of works power with load
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Factors Affecting Auxiliary Power Consumption
- Unit Generation and load Pattern - Operation of
Plant Auxiliaries - Service auxiliary such as
Illumination , air conditioning - Unit
Startup / shutdown
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STEPS INVOLVED IN CONDUCTING ENERGY AUDIT

• Data collection
• Measurements Observations
• Exploration for energy conservation measures
• Report preparation

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STEPS INVOLVED IN CONDUCTING ENERGY AUDIT

• DATA COLLECTION
• Motor details required-
• ID code, Application, Make, Brief details of
  driven equipment, Type of the Motor, Motor kW,
  Motor frame,
• Duty, Rated RPM, Rated p.f., Rated motor
  efficiency ,Motor make, Motor voltage, Rated
  current of motor, Year, Operating hours, Energy
  meter installed or Not , No. of times the motor
  is rewound
• Collect the above information for all
  motors to be covered in the energy audit.
• Collect the motor efficiency curves

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STEPS INVOLVED IN CONDUCTING ENERGY AUDIT

• Instruments Required-
• Power Analyzer Used for measuring electrical
  parameters such as kW, kVA, pf, V, A and Hz
• Infrared pyrometer (In case any heating of
  cable or motor is suspected)
• Stroboscope To measure the speed of the
  driven equipment and motor
• The above instruments can be used in
  addition to the calibrated online / plant
  instruments

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STEPS INVOLVED IN CONDUCTING ENERGY AUDIT

• Parameters to be measured-
• Energy consumption pattern of motors (daily
  / monthly /yearly consumption if available)
• Motor electrical parameters (kW, kVA, Pf,
  A, V, Hz, etc.) for individual motors
• Equipment operational details
• While conducting the measurement or performance
  evaluation of any system simultaneously, the
  following need to be noted
• Unit load of the plant
• Date time of measurement
• Instruments used for measurement
• Frequency of the measurement

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STEPS INVOLVED IN CONDUCTING ENERGY AUDIT

• MEASUREMENTSAND OBSERVATIONS
• System details
• Detailed interactions with the plant
  personnel
• Energy consumption Pattern
• If the plant is monitoring the
  energy consumption, it is suggested to
  record the data and monitor the daily and monthly
  consumption pattern

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STEPS INVOLVED IN CONDUCTING ENERGY AUDIT
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STEPS INVOLVED IN CONDUCTING ENERGY AUDIT
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STEPS INVOLVED IN CONDUCTING ENERGY AUDIT
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Motor loading survey

• Details
• Rated Kw
• Rated Efficiency
• Rated Speed
• Measurement of parameters
• Power factor
• kVA
• KW drawn
• Frequency
• Harmonics
• Motor speed
• Driven Voltage
• Current
• Power equipment speed
• Driven equipment parameters
• Operational observations Transmission
• loading on the motor

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STEPS INVOLVED IN CONDUCTING ENERGY AUDIT

• Motor loading can be estimated by
• Loading
• Input kW to motor x 100
• ----------------------------------------------
  -----------------------
• Name plate kW /Name plate full load motor
  efficiency

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STEPS INVOLVED IN CONDUCTING ENERGY AUDIT

• While conducting motor load survey,
  observations on machine side
• parameters such as speed, load, pressure,
  temperature, etc., (as relevant) are also taken
• availability of load-end capacitors for PF
  correction energy meters for monitoring is
  also looked into for each case.

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STEPS INVOLVED IN CONDUCTING ENERGY AUDIT

• Motor Rewinding History
• comparison of no load current and
  stator resistance
• per phase of a rewound motor with the
  original no-load
• current and stator resistance at the same
  voltage can be one
• of the indicators to assess the efficacy of
  rewinding.

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STEPS INVOLVED IN CONDUCTING ENERGY AUDIT

• Power Factor Correction
• Induction motors are characterized by
  power factors less than unity, leading to
  lesser efficiency (higher overall operating
  cost) associated with a plant's electrical
  system.
• Capacitors connected in parallel (shunted)
  with the motor are typically used to improve the
  power factor
• The impacts of PF correction include
  reduced kVA drawn , KVAR current, reduction of
  transformer load,
• Reduction of cable losses, reduction of switch
  gear rating,
• Enhanced life of equipment

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STEPS INVOLVED IN CONDUCTING ENERGY AUDIT

• EXPLORATION OF ENERGY CONSERVATION MEASURES
• Replacement / sizing of motors Opting for
  energy efficient motors, Use of high efficiency
  motors,
• Use of energy efficient transmission
• Replacement of pulleys
• Direct coupling

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STEPS INVOLVED IN CONDUCTING ENERGY AUDIT

• Analysis of observations
• Loading pattern - loading
• Comments of power supply quality
  
• The BIS standards specify that a motor
  should be capable of delivering its
  rated output with a voltage variation of 6
  and frequency variation of 3 . Motor
• Identified motors with less than 50 loading,
  50 75 loading, 75- 100 loading, over 100
  loading
• Identified motors with machine side losses /
  inefficiencies like idle operations,
  throttling/damper operations
• Motor load survey is aimed not only as a
  measure to identify motor efficiency areas but
  equally importantly, as a means to check combined
  efficiency of the motor, driven machine and
  controller

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AUXILIARY POWER CONSUMPTION

• Operating only 4 mills instead of 5 mills in 210
  MW units
• Shutting of CTs cells in conjunction with
  favorable weather conditions and replacing
  existing aluminum cast and GRP blades with FRP
• avoiding idle running of conveyors crushers
• incorporating soft starter - energy savers etc.
  

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AUXILIARY POWER CONSUMPTION

• STRATEGY
• Variable frequency drive for PA Fans ID Fans
  CEPs
• Air in-leaks in draft system (O2 measurement)
  blanketing
• Replacement of inefficient BFPs as a part of R
  M of the old plants.
• Clipping of one stage from the multi stage BFPs
  to balance the pressure drop requirements between
  HP heaters, economizer and boiler drum etc.
• Use of higher pressure in the deareator to
  commensurately reduce BFP power consumption
  (reduced head developed)
• Running of two CEPs instead of 3 CEPs (3 CEPs are
  run to avoid tripping due to lower frequency in
  some of the power plants)
• Application of variable speed drives
• Installation of hydraulic turbine instead of feed
  regulating section to avoid pressure drops and to
  generate additional power

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Thanks to all