The need for estimation of losses

1. Estimation of transmission losses for scheduling including inter-regional exchanges The need for estimation of losses Section 7.5 –4 – ii of Indian Electricity Grid code (IEGC): “The summation of station-wise ex-power plant drawal schedules for all ISGS after deducting the apportioned transmission losses (estimated), shall constitute the state-wise drawal schedule.” Importance • Wide difference in estimated & actual transmission losses would lead to huge mismatch in Un-scheduled Interchange (UI) payable & receivable. • Losses also assume importance while scheduling open access customers.

2. Estimation of transmission losses for scheduling including inter-regional exchanges • Transmission loss signifies the power lost while transferring the same from the generator(s) to the load. • In the context of scheduling under the Availability Based Tariff (ABT), generators above would mean the Inter- State Generating Stations (ISGS) while the load would mean the State drawals at their respective peripheries.

3. Estimation of transmission losses for scheduling (contd/-)

4. Estimation of Transmission losses for scheduling (contd/-) • Through power flow studies (one day in advance) • - Accurate but complex as different conditions have to be envisaged. Further state level generation/load data required. • Based on average actual pooled losses calculated from net drawal of constituents & net injection of ISGS for previous weeks using Special Energy Meter (SEM) data. • - Simple and easy to implement. Following to be kept in mind: • Changes in load & Generation pattern over the time. (averaged actual losses will be more realistic if pattern does not change drastically)

5. Estimation of Transmission losses for scheduling (contd/-) • In the Northern Region, the transmission losses for the ISGS portion varies by as much as 1 to 1.5% within the day on account of variations in BBMB and ISGS hydro stations. • However, the average transmission losses day-wise does not vary much during the entire week except in situations like closure of hydro stations due to flushing of reservoir or forced outages.

6. Estimation of Transmission losses for scheduling (contd/-) • It is suggested that we gradually move to the power flow study method to estimate the losses for the purpose of day-ahead scheduling as it is more scientific. • In case a clear pattern of losses is noticed in the course of the entire day, we could go in for a time block-wise figure of estimated losses.

7. Estimation of Transmission losses for scheduling (contd/-) • Inter-regional exchanges through an intervening region • What should be the approach followed for the transmission losses in the intervening region? • Should it be the pooled loss percentage or the incremental loss approach?

8. Estimation of Transmission losses for scheduling (contd/-) • Inter-regional exchanges through an intervening region (contd/-) • Incremental loss method, although scientific is not desirable as the base case itself varies from time to time. • In case of open access customer, the last set of customers may be at a disadvantage, if incremental transmission losses are levied.

9. Estimation of transmission losses for scheduling (contd/-) • Inter-regional exchanges through an intervening region (contd/-) • Pooled loss approach would be more simpler initially and more transparent. • Later as we move to the system study method for loss estimation and as we gain experience in respect of open access customers, we could move to the incremental loss approach.

10. NRLDC Charges and Fees -Status • *J&K has opened LC for Rs. 5 Cr/ month while its average transmission & RLDC (4.5 Lacs) bills are in range of 7.0 Cr. • For April & May 2002 Bills (Rs. 1437050 +Interest) raised on DVB, are not realised (time of unbundling of DVB)

15. Energy traded in Northern Region ABT: Availability Based Tariff The Unscheduled Interchange (UI) market is also of the order of 500 MU every month