Load management, tariff in DSM, tariffs in Nepal

Role of load management in DSM

Load management is the part of DSM that controls the time and level of demand (rather than total energy) so that the load curve becomes flatter.

• Peak clipping: reduces load at system peak through direct load control or interruptible supply.
• Valley filling: adds load during off-peak periods (night pumping, EV charging).
• Load shifting: moves flexible loads from peak to off-peak time.
• It improves load factor, reduces peak generation and network capacity needs, avoids load shedding, and lowers the cost of supply. Tools are tariffs, ripple/remote control of loads, timers, storage and smart meters.

 Demand
   |       /\  peak       --> clipped / shifted
   |   ___/  \___
   |  /          \__  valley --> filled
   +------------------ time

Tariff as a part of DSM

A tariff is the rate schedule by which a utility charges consumers. Besides recovering costs, a tariff sends price signals that change consumer behaviour:

• Time-of-day (ToD) tariff: high rate at peak, low at off-peak, so consumers shift loads.
• Seasonal tariff: different rates for wet and dry seasons to match hydro availability.
• Demand (kVA) charge: charges maximum demand, so consumers limit peaks and improve pf.
• Power factor penalty/incentive: encourages capacitors.
• Interruptible tariff: lower rate for consumers who accept curtailment.
• Block (slab) tariff: increasing rates for higher use encourage conservation.

Types of tariff implemented in Nepal (NEA)

As per the NEA tariff schedule (rates revised by the Electricity Regulatory Commission from time to time):

1. Domestic: by ampere rating (5, 15, 30, 60 A and 3-phase); a monthly minimum/service charge plus block (slab) energy charges that increase with consumption; a low lifeline rate for small users.
2. Two-part tariff: for industrial, commercial and other larger consumers: demand charge (Rs/kVA/month) + energy charge (Rs/kWh), different for LV, MV (11/33 kV) and HV (66/132 kV) supply.
3. Time-of-day (ToD) tariff: for MV/HV industries and other bulk consumers: peak (about 17:00–23:00), normal (05:00–17:00) and off-peak (23:00–05:00) energy rates, with seasonal (wet/dry) variation.
4. Category tariffs: separate rates for industrial, commercial, non-commercial, irrigation, drinking water, transport/EV charging, street lights, temples and community (bulk) consumers.
5. Power factor provision: consumers billed on kVA demand, with penalty for pf below the specified limit.
6. Bulk supply tariff: for community electricity user groups, who distribute locally.