Availability Based Tariff (ABT) is a frequency based pricing mechanism for electric power. The ABT falls under electricity market mechanisms to charge and regulate power to achieve short term and long term network stability as well as incentives and dis-incentives to market participants against deviations in committed supplies as the case may be.
ABT Mechanism (Energy policy of India) is adopted in India (ABT Order dated January 2000 of CERC) and in a few other countries for pricing bulk power across various stakeholders. ABT concerns itself with the tariff structure for bulk power and is aimed at bringing about more responsibility and accountability in power generation and consumption through a scheme of incentives and disincentives. As per the notification, ABT was initially made applicable to only central generating stations having more than one SEB/State/Union Territory as its beneficiary. Through this scheme, the Central Electricity Regulatory Commission (CERC) looks forward to improve the quality of power and control the following disruptive trends in power sector:
- Unacceptably rapid and high frequency deviations (from 50 Hz) causing damage and disruption to large scale industrial consumers
- Frequent grid disturbances resulting in generators tripping, power outages and power grid disintegration.
**The ABT scheme has now been expanded to cover the Intrastate systems as well.
What is availability?
'Availability', for the purpose of the ABT Order means the readiness of the generating station to deliver ex-bus output expressed as a percentage of its related ex-bus output capability as per rated capacity.
How is availability calculated?
“Availability of thermal generating station for any period shall be the percentage ratio of average SOC for all the time blocks during that period and rated Sent Out Capability of the generating station”
- Each day of 24 hours starting from 00.00 hours be divided into 96 time blocks of 15 minutes each.
- Each generating station is to make advance declaration of its capacity for generation in terms of MWh delivery ex-bus for each time block of the next day. In addition, the total ex-bus MWh which can actually be delivered during the day will also be declared in case of hydro stations. These shall constitute the basis of generation scheduling.
- While declaring the capability, the generator should ensure that the capability during peak hours is not less than that during other hours.
- The Scheduling as referred to above should be in accordance with the operating procedures in force.
- Based on the above declaration, the Regional Load Dispatch Centre(RLDC) shall communicate to the various beneficiaries their respective shares of the available capability.
- After the beneficiaries give their requisition for power based on the generation schedules, the RLDC shall prepare the generation schedules and drawal schedules for each time block after taking into account technical limitations and transmission constraints.
- The schedule of actual generation shall be quantified on ex-bus basis, whereas for beneficiaries, scheduled drawals shall be quantified at their respective receiving points.
- For calculating the drawal schedule for beneficiaries, the transmission losses shall be apportioned in proportion to their drawals.
- In case of any forced outage of a unit, or in case of any transmission bottleneck, RLDC will revise the schedules. The revised schedules will become effective from the 4th time block, counting the time block in which the revision is advised by the generator, to be the 1st one.
- It is also permissible for the generators and the beneficiaries to revise their schedules during a day, but any such revisions shall be effective only from the 6th time block reckoned in the manner as already stated.
- ABT brings about enhanced grid discipline
- Economically viable power with right pricing
- Promote competition and efficiency
- Encourage use of Merit Order Dispatch / Economic Dispatch in India
- Addressing grid disturbance issues
- Gaming and avoiding the same
- Requires special meters, remote metering with open protocols and communication mechanisms to read meters timely
- Software that is comprehensive to do calculations, address regulatory issues and modifications as per different Regulatory Commission requirements.
- Interface options to various stakeholders in the ABT mechanism online to enable effective implementation and benefits to all
- Capability of power producers to be able to control their cost of production as well as flexibility in operations