Energy Audit



Necessity:


  • Financial health of SEBs – a matter of grave concern
  • Losses- Rs. 50,000 crores= 1.5% of GDP
  • 55% of energy billed; 41% realized
  • ATC losses= 45-50%
  • Find out: where is the leakage, wastage or inefficient use


T & D Losses:

  • T&D losses in India-among the highest in the world:35-45%
  • Due inadequate investments over the years for system improvement works
  • Unplanned extension of distribution lines
  • Overloading of lines and transformers
  • Lack of adequate reactive power

AT&C Losses:


  • As the T&D loss was not able to capture all the losses in the network, concept of Aggregate Technical and Commercial loss was introduced
  • It captures technical as well as commercial loss in a system
  • It is a true indicator of total losses in the system

Commercial Losses



Mainly due to Low metering Efficiency, Theft and Pilferage.

Remedy

  • Improving meter efficiency
  • Proper energy accounting and auditing
  • Improving billing and collection efficiency
  • Fixing of accountability on the employees


Energy Audit: Definition



The verification, monitoring and analysis of use of energy including submission of technical report containing recommendation for improving energy efficiency with cost benefit analysis and an action plan to reduce energy consumption

Steps involved in Energy Audit

  • Network Documentation: an activity that covers network survey in the field and documentation of the surveyed network in software
  • Consumer Indexing: an activity to identify location of consumers in a distribution network and identifying their source of supply


Network Documentation: Survey

  • The survey starts from the MUSS where from 11 kV lines emanate. It covers:
  • Tracing the HT lines
  • Noting the conductor used
  • Noting the HT poles and type of poles
  • Noting the location and capacity of Transformers
  • Tracing the LT lines
  • Noting the conductor used and the wire configuration of the LT lines
  • Noting the LT Poles and type of poles
  • Noting the number of consumers (service cables) connected to each pole, with approximate service cable size and length
  • Codifying/numbering the poles
  • Once a survey is carried out, it is necessary to document the survey findings in a suitable software

Method or process for field survey :



  • Field surveys are generally carried out by low skill manpower and there is need to have a system in place survey efforts are not duplicated, all areas covered, quality checked.
  • It is advisable start with a map of the area where a network survey is needed.
  • Satellite based maps is very useful.


Steps in a survey :



  • Digitize the map. Assign different layers for roads and buildings. .
  • Indicate the scale in the map.
    •  
  • Mark useful and important landmarks.
  • Survey team then marks poles, transformers, lines, distance between poles, consumers.
  • Type of poles, configuration of wires, capacity of transformer are noted.

Consumer Indexing:


  • Many carry walk through surveys.
  • This is error prone because of jumble of wires and underground of cables.
  • In some cases, the power supply is switched off to find out which house has gone dark so that consumers can be identified
  • Keep consumer identification updated regularly


Energy Accounting & Audit:


  • Energy Accounting is a statement of energy input, output and loss for a system for a specified period of time.
  • Energy Audit is the segregation of the total loss as found from energy accounting into the technical and commercial loss components.


Difficulties in Energy Accounting:



  1. Consumer end meter readings are taken on staggered dates.
  2. Many houses are locked, meters are faulty leading to provisional billing.
  3. Consumers are disconnected mid-way during a month.
  4. New connections are given any time in a month.
  5. There is change in electrical configuration and some consumers may be supplied power from different feeders during a month.
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