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Friday, 17 October 2014

Methods to reduce Distribution Losses

What is Transmission & Distribution (T&D) Losses?

The losses occurring in the transfer of power from the generator to the end consumer is known as Transmission and Distribution (T&D) losses. Apart from T & D losses there are commercial losses too and therefore, the concept of Aggregate Technical and Commercial (AT & C) loss was introduced which truly reflects the technical as well as commercial losses in the whole electrical network.

Value of AT & C Losses at various levels:

The AT & C losses vary in various Indian states from 20 to 45% because of the difference in load density, type of network (urban or rural lines), pre-dominant sub-transmission voltage, voltage of supply, geographical size of the area etc. Other factors such as inadequate design, monetary investments and bad maintenance of the system over the years contribute to higher losses. 
Nearly 8% of the total AT & C losses take place above 33 kV level and the rest do happen below 33 kV.  

Methods to reduce AT & C Losses:

Aggregate Technical and Commercial (AT & C) loss of 20 to 45% for any state is very much higher from any international standard and has to be curtailed down. 

The various methods that can reduce these losses are:

1.      Installation of static VAr controller in the distribution system. Switchable shunt capacitors at the sub-station or on lines can be very useful in providing the required reactive power.
2.     Use of low loss transformers, particularly the distribution transformers. Distribution transformers with amorphous core have very low iron losses.
                   Fig: Standard Iron & Copper losses of some of the Distribution Transformers

3.      Re-conductoring the overhead line with conductors of appropriate size.
4.      Keeping the loads on power and distribution transformers within limit.
5.      Shifting the distribution transformers to load centres.  
6.      Balancing the load on the three phases of the lines.
7.      Distributed generation or local generation can also reduce the line losses.
8.  Adopting High Voltage Distribution System (HVDS), employing small capacity distribution transformers, for agricultural pumps and theft prone residential areas.
9.     Installation of microprocessor based static (electronic) energy meters incorporating special features like tamper data, Time-of- Day (TOD) metering, load pattern analysis, remote meter reading.

10. Adopting for Distribution Automation System (DAS).   

Capacitor Bank installed at a sub-station