FAX : Member Secretary Southern Regional Power Committee 29, Race Course Cross Road Bangalore FAX :

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2 Distribution List : 1. Shri Ravinder Member (Power Systems) Central Electricity Authority Sewa Bhawan, R K Puram New Delhi FAX : CEO POSOCO B-9, Qutab Institutional Area Katwaria Sarai, New Delhi FAX : Member Secretary Southern Regional Power Committee 29, Race Course Cross Road Bangalore FAX : Shri K. K. Arya Chief Engineer(SP & PA) Central Electricity Authority Sewa Bhawan, R.K.Puram New Delhi FAX : Member Secretary Western Regional Power Committee MIDC area, Marol, Andheri (E) Mumbai FAX : Western Region Constituents 1. Managing Director Gujarat Energy Transmission Corp. Ltd, Sardar Patel Vidyut Bhawan, Race Course, Vadodra FAX : Director (Operation) MSETCL. 4 th Floor, Prakashganga Plot No. C-19, E-Block Bandra Kurla Complex, Bandra(East), Mumbai FAX : / The Chief Engineer Electricity Department The Government of Goa Panaji FAX : Executive Engineer Electricity Department UT of Dadra & Nagar Havelli, Post Naroli Silvassa FAX : / Chairman & Managing Director MPPTCL, Block No. 3 Shakti Bhawan, Rampur, Jabalpur FAX : Managing Director Chhattisgarh State Transmission Co. Ltd. Dangania Raipur FAX : Executive Engineer UT of Daman & Diu Administration, OIDC Corporate Office, Plot No. 35 Somnath, Daman,Pin FAX : / GM, WRLDC F-3, M.I.D.C. Area Marol, Andheri (E) Mumbai FAX :

3 Southern Region Constituents 1. Director (Transmission) Transmission Corp. of Andhra Pradesh Ltd. Vidyut Soudha Hyderabad FAX : Member (Transmission) Kerala State Electricity Board Vidyuthi Bhawanam, Pattom, P.B. No Thiruvananthapuram FAX : Superintending Engineer I First Floor, Electricity Department Gingy Salai Puducherry FAX : / Member (Transmission) Karnataka State Power Transmission Corp.Ltd. Cauvery Bhawan Bangalore FAX : Director (TANTRANSCO) Tamil Nadu electricity Board (TNEB) 6 th Floor, Eastern Wing, 800 Anna Salai, Chennai FAX : ED (SRLDC) Southern Regional Load Dispatch Centre 29, Race Course Road Bangalore FAX :

4 Total Transfer Capability (TTC), Transmission Reliability Margin (TRM) and Available Transfer Capability (ATC) between NEW Grid and SR - Agenda 1. As per CERC Regulations, Long-term Access (LTA) & Medium-term Open Access (MTOA) are to be granted based on the TTC, TRM & ATC calculated by CTU. The TTC, ATC & TRM and their determination has been covered under the detailed Procedure approved by CERC for relieving congestion in real time operation under Regulation 4 (2) of the Central Electricity Regulatory Commission (Measures to relieve congestion in real time operation) Regulations, The relevant paragraphs of the same are reproduced below: (a) Total Transfer Capability (TTC) means the amount of electric power that can be transferred reliably over the inter-control area transmission system under a given set of operating conditions considering the effect of occurrence of the worst credible contingency. (b) Transmission Reliability Margin (TRM) means the amount of margin kept in the total transfer capability necessary to ensure that the interconnected transmission network is secure under a reasonable range of uncertainties in system conditions. (c) Available Transfer Capability (ATC) means the transfer capability of the inter control area transmission system available for scheduling commercial transactions (through long term access, medium term open access and short term open access) in a specific direction, taking into account the network security. Mathematically ATC is the Total Transfer Capability less Transmission Reliability Margin. (d) Computation of TRM for a region or control area or group of control areas would be based on the consideration of the following:

5 Two percent (2%) of the total anticipated peak demand met in MW of the control area/group of control area/region (to account for forecasting uncertainties) Size of largest generating unit in the control area/group of control area/region 2. As on date, TTC and ATC between NEW grid & SR has been stipulated as 3450 MW with TRM as zero (Talcher-Kolar HVDC bipole : 2000 MW, Chandrapur HVDC backto-back : 850 MW & Gazuwaka HVDC back-to-back : 600 MW). With the commissioning of Solapur-Raichur 765 kv corridor the transfer capability, ATC & TTC shall undergo revision. 3. Detailed studies for feasible power transfer over this 765 kv corridor were carried out by CTU and the results of which were circulated earlier. Based on these, in a meeting chaired by Chairperson, CEA held on 3 rd October 2013, involving WR & SR constituents, POSOCO, CEA & CTU, it was decided that additional 2000 MW of power can be transferred through Solapur-Raichur 765 kv lines subject to commissioning of identified transmission lines in WR & SR (details given in Annexure-1). While arriving at the TTC value of 2000 MW various credible contingencies as per the Transmission Planning Criteria were considered. The different flowgates between ER & SR through WR (ER-WR, W3, Wardha flowgate) were examined and no congestion was observed in these flowgates. 4. The TRM is meant to cover uncertainties for the correctness of the assumptions considered while arriving at TTC like aggregate load forecast, load distribution, forecasted transmission topology, Allowances for parallel path (loop flow) impacts and simultaneous path interactions, Variations in the generation dispatch, Inertial response and frequency bias etc. As per the procedure approved by CERC, TRM is to be derived based on two considerations viz. 2% of peak demand met and largest unit size. The analysis for TRM based on above considerations is as below:

6 (a) 2% of Peak Demand met - This uncertainty is aimed at addressing the deficit in net power availability in the importing region thereby causing unintentional power flow across the flowgate. The deficit can be on account of numerous reasons like error/mismatch in projected load, error/mismatch in generation dispatch, load distribution variation etc. Under the unintended deficit in the importing SR, the power flow can take place from NEW grid to SR. The change in the power flow on tie-lines shall be dependent on the relative stiffness of two interconnected systems. The change in power for a given change in the frequency in an interconnected system is known as the stiffness of the system. The smaller the change in frequency for a given load change the stiffer the system. The power-frequency characteristic may be approximated by a straight line and P/ f = K, where K is a constant (MW per Hz) depending on the governor and load characteristics. The stiffness constant of interconnected systems is dependent on variety of reasons like Governor action, type of load (lighting, agriculture, industrial etc) hence it varies over the seasons and during the day. The Stiffness Constant (Power Order) for SR is considered between MW/Hz and the Power order for NEW Grid varies between 2000 to 3500 MW/Hz. Solapur Raichur 765 kv 2xS/c lines NEW Grid (N), K N ( P t ) SR Grid (S), K S P ( P t ) = Change in the Power transferred from NEW Grid to SR Grid when a change resulting in an out-of-balance Power P occurs in the SR Grid.

7 This out-of-balance power P is due to either above criteria or variations in daily load curve on account of diversity in loads, load changeovers etc. P t = + (K N )/( K N + K S ) * P Generally, ( P) = P L - P G Where P L is change in load, P G is change in generation due to Free Governor Mode of Operation (FGMO). Presently, the generators are operating in Restricted Governor Mode of Operation (RGMO) and hence P G may treated as Zero. The largest value of P t resulting from any of the above events may be kept as TRM value for accounting balancing power between two Regions. Therefore 2% is 720 MW ( P) considering MW peak demand for SR (based on CEA Power Supply Position report for September, 2013, SR peak demand met is MW + import through Solapur-Raichur corridor). NEW Grid Power Order (MW/Hz) SR Grid Power Order (MW/Hz) Power flow in Tie Line (MW) P t (b) Outage of largest unit - This uncertainty is aimed at addressing the deficit in net power availability in the importing region when largest unit trips thereby causing unintentional power flow across the flowgate on account of Inertial response and frequency bias. The largest unit in SR in the intended time frame shall be Kudankulam (1000 MW). The Kudankulam generation is equipped with Special Protection Scheme (SPS) for load reduction on account of unit tripping similar to SPS for tripping Talcher-Kolar HVDC bipole. The past experience of 4 years of SPS operation of Talcher-Kolar HVDC indicates actual load relief obtained of 50-80%, sometimes reaching to 150% also. Further, Success of SPS operation is about 80%. Therefore, studies have been carried out for a 1000 MW unit tripping of

8 Kudankulam with 50% effectiveness of SPS. It is seen that this causes increase in loading on Solapur-Raichur 765 kv line by about 350 MW. In comparison, if the next largest unit in SR i.e. 600 MW is tripped it causes increase in loading on Solapur-Raichur 765 kv line by about 420 MW. It is pertinent to mention here that the general international practice to account for this uncertainty is to consider tripping of generation units having larger population rather than the largest unit. Based on the (a) and (b) above, it is proposed that the TRM for NEW grid to SR grid interconnection may be considered as 500 MW. As explained at Para 1. (c), ATC = TTC-TRM therefore additional ATC shall be 1500 MW ( MW) due to commissioning of Solapur-Raichur 765 kv lines. 5. As per the CERC regulations, the ATC is to be allocated to LTA and MTOA applicants in the order of priority. In this regard, the CERC regulations (regulation 12) states that "Provided that a generating company after firming up the beneficiaries through signing of long term Power Purchase Agreement(s) shall be required to notify the same to the nodal agency along with the copy of the PPA." In line with the above provision, CTU has received requests for regularization of LTA by following applicants that had earlier been granted LTA based on target region/beneficiaries. The details are as given below: Sl. No. Applicant LTA Quantum (MW) Injection Point Drawl Point LTA Start Date sought 1 Ind-Bharat (Utkal) Power Limited 500 Jharsuguda Pooling Station, Odisha TANGEDCO 1 st February Jindal Power 400 Raigarh TANGEDCO 1 st Limited (Tamnar), February Chattisgarh DB Power 208 Raigarh (Kotra), TANGEDCO 1 st 30 th End Date sought 30 th September th September 2028

9 Sl. No. Applicant LTA Quantum (MW) Injection Point Drawl Point LTA Start Date sought Limited Chattisgarh February BALCO 100 Dharamjaigarh, TANGEDCO 1 st Chattisgarh February 2014 End Date sought September th September 2028 (a) In the meeting held on 3 rd October 2013, on the suggestion of POSOCO, it was agreed that no scheduled energy shall be allowed on Solapur-Raichur 765 kv lines for initial six months of synchronous operation. It is expected that the synchronization of NEW grid with Southern Region shall take place on 1 st February 2014 then ATC on this corridor shall be effective from 1 st August In the event of synchronization getting delayed than the effectiveness of ATC shall also be deferred by same time (i.e. if synchronization gets delayed by x months than ATC effectiveness delayed by x months). This ATC has been worked out considering the availability of all the transmission lines (as indicated at Annexure-1). In case of nonavailability of any of these lines, ATC shall be reviewed 3 months prior to applicability of this ATC considering the lines available at that time. Taking above into consideration it may be seen that from 1 st August, 2014 onwards there shall be enhancement of ATC by 1500 MW post stabilization of Solapur Raichur 765 kv interconnection considering the existing and identified transmission system. Thus the total ATC of NEW grid to SR shall be 4950 MW ( ). 6. Based on the above ATC it is proposed to consider grant of LTA to above applicants from to xxxx-----

10 Annexure-1 For transfer of 2000 MW over Solapur-Raichur 765 kv 2xS/c lines, the availability of following lines is required in Western Region Aurangabad-Pune 400 kv D/c line under implementation by Reliance Power Transmission Limited. The Parli-Pune 400 kv D/c line has been recently commissioned. Raipur-Wardha-Aurangabad 765 kv D/c line Solapur-Pune 765 kv S/c line Southern Region Gooty-Madhugiri-Yelahanka 400 kv D/c line Raichur-Kurnool 765 kv S/c Kurnool-Thiruvalem 765 kv D/c line Vijayawada-Nellore-Thiruvalem-Malekottaiyur 400 kv D/c lines.