Proposed Framework on “Forecasting, Scheduling & Imbalance Handling for Renewable Energy (RE) Generating Stations based on wind and solar at Inter – State Level”.
Forecasting needs to be done by both the wind/solar generator and the concerned RLDC. While the forecast by the concerned RLDC would be more with the objective of secure grid operation, the forecast by the wind / solar energy generator would be wind-farm/solar facility centric and would form the basis of scheduling. Appropriate use of forecast for scheduling is also expected to reduce commercial impact for the wind and solar energy generators. It is understood that the Renewable Energy Management Centers (REMCs) are being established and these would be equipped with advanced forecasting tools. The wind/solar energy generator may choose to utilize its own forecast or the forecast given by REMC/concerned RLDC. However, any commercial impact on account of scheduling based on the forecast would be borne by the wind/solar energy generator. It would also be prudent to have multiple forecast providers (both for REMC/RLDC & wind/solar energy generators) for better confidence levels/lower forecast errors.
Proposed Deviation Mechanism:
When the wind/solar energy generator under-injects, he still receives payment for the energy injected as per schedule @ wind/solar Tariff. However, because of deviation he would be liable to pay a pre-defined charge to the DSM Pool and also buy REC for the energy equivalent to deviation. The total payout for the wind/solar energy generator should be such that it modulates its behavior to remain within the desired operating band as far as possible.
The same philosophy should apply for over-injection as well.
If the actual generation is in the range 88% to 100% of schedule, the wind/solar generator would pay for the shortfall energy @ Rs. 3/kWh (may be reviewed periodically by the Commission through an Order) to the DSM Pool. In addition, the wind/solar energy generator would buy RECs (equivalent to the shortfall energy) and transfer them to the buyer to enable it to fulfill its RPO obligation. Assuming the current market rate of REC at Rs. 1.50/-per unit for non-solar and Rs 3.50 per unit, the outgo for a wind/solar energy generator [Rs 3 plus Rs 1.50 per unit (assumed REC price) for wind energy generator and Rs 3 plus Rs 3.50 per unit assumed REC price for solar energy generator] would be less than what it earns based on scheduled generation [Rs 5 per unit for wind energy generator and Rs 7 per unit for solar energy generator (assumed wind and solar tariffs respectively)] ,if it operates within 12% deviation. This is being consciously allowed to motivate the Wind/Solar energy generator to remain within the desirable band of 12% deviation. This can be treated as an incentive for better forecasting.
If the actual generation is below 88%, the wind/solar energy generator would pay @ Rs. 4/kWh for the shortfall energy to the DSM Pool (may be reviewed periodically by the Commission through an Order). In addition, the wind/solar energy generator would buy RECs (equivalent to the shortfall energy) and transfer them to the buyer to enable it to fulfill its renewable purchase obligation. In this case (that is, in the event of deviation beyond 12%), there is a clear disincentive as the outgo for the wind/solar energy generator would be more than what it earns based on scheduled generation.
If the wind/solar energy generator over-injects, ideally it should not be paid for as the variable cost is zero. However, in order to encourage wind/solar energy generation, when the actual generation is in the range of 100% to 112% of schedule, the wind/solar energy generator would be paid @ Rs. 4/kWh for the excess generation (may be reviewed periodically by the Commission through an Order). In addition, the wind/solar energy generator would also be issued RECs for such excess generation. Here again, there is an incentive for the wind/solar energy generator for remaining within the band of positive 12%.
Beyond 12% on the positive side, the wind/solar generator would be issued only RECs for the excess generation. No payment would be made to such generators from the DSM Pool for generation above 112% of the schedule.
In the above process, the charges for deviation from schedule for wind/solar energy generator would be delinked from the frequency based charges as applicable under the DSM mechanism.