Electricity pricing
Tariffs
Tariffs
•Definition:
•Different methods for chargingconsumers,
•Rate of payment for consumption ofelectricity
Some basis
•Purely on Total energy (kwh) consumption
•Maximum demand and total energy consumption
•Amount of energy consumed
•Power factor of the load
•Time at which the load is required
•Type of the customer ( Industrial , commercial orresidential )
•HT (High voltage) & LT customers
Some basis
•Purely on Total energy (kwh) consumption
Flat rate tariff
•Maximum demand and total energy consumption
Two part Tariffs
•Amount of energy consumed
Block rate Tariff
•Power factor of the load
Power factor Tariff
•Time at which the load is required
Time of the Day Tariff
Some basis
•Type of the customer ( Industrial ,commercial or residential )
•HT (High voltage) & LT customers
Industrial consumers
•Basis of charging Industrial consumers isgenerally Two part tariffs;
•One part of charge is proportional to the maximumdemand ( kilowatts) because this affects the size ofthe plant to be installed and corresponding fixedcharges on capital.
•The second part of charge is proportional to theenergy consumed (killowatt-hours) monthly orannually.
Residential consumers in Early days
• In early days policy was to inducecustomers to use more energy, somecompanies used two or more flat rates
•First few kwh are charged at certain rate,the next few at a lower rate, next few at astill lower rate and so on.
Residential consumers Now a days
•Due shortage of generation Now a dayspolicy is to discourage customers to usemore energy, some companies use two ormore flat rates
•First few kwh are charged at certain rate,the next few at a higher rate, next few at astill higher rate and so on.
Incentives and penalty
•Consumers taking off peak power Special cheaprates to help to improve the load factor of thesystem.
•Consumers whose pf falls below a specified limitmay be charged more; have a penalty clause inthe rate structure.
•Alternatively the consumers may be charged oncombined killovolt-ampere-hour ( kVA) andkillowatt-hour (kwh)basis.
Modern techniques
•Electricity Regulatory commission ( ERC)governs the fixation of tariffs for variousConsumers.
•The rate structure should be arranged so asto help the system to have better load factorand power factor so that electrical energycan be produced and sold more cheaply.
Energy supplied to consumers
G
kwh generated
kwh used by stationauxiliaries
Kwh loss intransmission
kwh Received
Energy to consumer = kwh generated – kwh used by aux – kwh loss in transmission
Some Examples
•2.9 (mvd)
•Apower station has a installed capacity of 20000 kw , thecost of the station is rs 1200, per kw . The fixed costs are13% of the cost of investment. On full load at 100% loadfactor, the variable cost of the sttio per year are 1.5 timesthe fixed costs.Assume that there is no reserve capacity ofthe plant and that the variable cost are proportional to tothe energy production Find the cost of generation per kwhat load factors of 100% 80%, 60%, 40% and 20% and plotthe curve. (ans Load fctors and cost per kwh; 100% 4.46p,; 80% 5.65p; 40% 7.15p; 20% 11.5p)
Some Examples
•2.10 (mvd)
•Apower station has a installed capacity of 20000 kw , the cost of the station is rs 1200, per kw . Thefixed costs are 13% of the cost of investment. On full load at 100% load factor, the variable cost ofthe sttio per year are 1.5 times the fixed costs.Assume that there is no reserve capacity of the plantand that the variable cost are proportional to to the energy production Find the cost of generation perkwh at load factors of 100% 80%, 60%, 40% and 20% and plot the curve. (ans Load fctors and costper kwh; 100% 4.46p ,; 80% 5.65p; 40% 7.15p; 20% 11.5p)
•Tis station supplies load to consumers. The cost of distribution system increases the fixed cost by75% { this includes payment of dividend to stock holders} and the variable cost on full load at 100%load factor( at the station) by 20% Work out the two part tariff per killowatt per month and per kwhconsumed.
•When a) the load factor is 80% and (i) the diversity factor among the consumer is 2.3 and (ii) thediversity factor among the consumer is 1.75
•b) the load factor is 60% and (i) the diversity factor among the consumer is 2.3 and (ii) the diversityfactor among the consumer is 1.75
•The losses in the distribution system may be taken as 10%
•( Ans: (a) (i) Rs 9.75per kw per month and Rs 3.59 per kwh;(ii) Rs 12.8per kw per month and Rs3.59 per kwh
•(b) (i) Rs 9.75per kw per month and Rs 3.59 per kwh;(ii) Rs 12.8per kw per month and Rs 3.59 perkwh