TRANSMISSION SYSTEM PLANNING UNDER UNCERTAINTY OF SUPPLY AND DEMAND IN INDIAN CONTEXT. I S Jha Y K Sehgal* Subir Sen

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1 21, rue d Artois, F PARIS C1-114 CIGRE 2012 http : // TRANSMISSION SYSTEM PLANNING UNDER UNCERTAINTY OF SUPPLY AND DEMAND IN INDIAN CONTEXT I S Jha Y K Sehgal* Subir Sen Power Grid Corporation of India Ltd Gurgaon, INDIA SUMMARY Electricity demand in Indian Power System is expected to be more than 200GW in next 5-6 years for which more than 75GW capacity additions has been envisaged during 12 th Plan( ). Additionally, more than 30GW has been envisaged to be added through grid interactive renewable energy resources which includes about 19GW through wind and 10GW through solar energy. Both Govt/Public and private sectors are participating in big way in all segments of electricity supply chain i.e., generation, transmission and distribution. The Electricity Act, 2003 enabled setting up of IPPs(private generation project) along with open access. In this direction, large capacity addition has been envisaged through IPPs at various complexes in the State of Orissa, Jharkhand, Chhattisgarh, Tamil Nadu etc. without firm beneficiaries/commissioning schedule. Such uncertainties along with right of way (RoW) pose challenges to the transmission planner for development of transmission system. A new concept for transmission system planning under uncertainty of supply and demand levels for transfer of power to target destinations/direction is presented. The challenges for development of transmission system under such uncertainties as well as implementation mechanism along with recovery of investment are deliberated. Emerging technology integration in the development of transmission system in modular way is also highlighted. A case study with specific reference to development of high capacity transmission corridors for various IPPs in Chhattisgarh, M.P in Western region and Jharkhand, Orissa in Eastern Region is also presented. KEYWORDS Beneficiary, Investment, Planning, Technology, Transmission, Schedule, Uncertainty 1

2 1. INTRODUCTION Power system in India is growing at an accelerated pace. Electricity demand is expected to be increased to more than 200GW in next 5-6 years for which over 75GW capacity additions has been envisaged during 12 th Plan. Additionally, about 31GW has been envisaged to be added through harnessing grid interactive renewable energy resources which includes about 19 GW through wind and 10 GW through Solar energy. Currently, the sector is passing through an evolutionary phase and numerous radical changes are taking place in the structural, institutional and operational arrangements. Both Govt/Public and private sectors are participating in large scale in all facets of electricity supply chain i.e., generation, transmission and distribution. This has resulted into paradigm shift in the way with which the power sector is being viewed. Further, the consumer today is looking for Secure, reliable and quality power at affordable price. The Electricity Act, 2003 has created new paradigm for the development of power sector in our country. It has created a new competitive framework for the development of the Power Sector with focus on the consumer and safeguarding his interest through Independent Regulatory Commissions. The Act enables delicensing of generation, transmission as license activity, trading as distinct activity, non discriminatory Open Access in transmission, no more fixed formulae (unlike earlier fixed formula) for allocation of power to the regional constituents rather they are to be determined based on Competitively bid generation tariff, consumers can procure power from different sources through competitive bidding process etc. As a result, large capacity addition of the order of 180 GW has been envisaged under Govt. and private sector in next 5-6 years without identifying actual destination points i.e, beneficiaries of most of the generation projects. Mostly projects are proposed to be located at pocketed pit-head/resource areas with each location having capacity in the range of 5-10 GW. This necessitates transfer of bulk power to the far-off load centers through long distance transmission system. Various factors like identification of system strengthening in the absence of firm beneficiaries, conservation of eco-sensitive Right-of-Way(ROW), protection of flora & fauna, flexibility to enhance corridor capacity, recovery of investment etc. are posing major challenges towards planning and development of suitable transmission system. In this paper, major considerations for transmission system planning under uncertainties for transfer of power from various generation projects to target destinations are presented. Various issues that need to be addressed towards development high capacity transmission system, comprising ±800kV, 6000MW HVDC and 400kV/765kV AC system with provision to upgrade to 1200kV at a later date, taking into account other factors are also highlighted. Emerging technology integration in the development of transmission system in modular way is also highlighted. A case study in this regard is also presented. 2. OVERVIEW OF INDIAN POWER SYSTEM Indian Power System is demarcated into five(5) electrical regions viz, Northern, Eastern, Western, Southern and North-eastern Regions as shown at Fig.1 below: NR Fig.1: Regional boundary of Indian Power System WR ER NER LAKSHADWEEP SR ANDAMAN & NICOBAR 2

3 Present Installed capacity of Indian Power System is about 186 GW and the peak power demand is about 127 GW. The trunk transmission system in all the regions is dominated by 400kV level networks. The grid comprises about 4500 ckt. kms 765kV lines, 106,000 ckt. km of 400kV lines. In addition, four(4) HVDC bipoles (8000MW), seven(7) HVDC back-to-back (3000MW) links are under operation. Today, as a part of National Grid, central grid comprises of Northern, Western, Eastern & North-eastern regions are operated as a single grid of more than 137 GW and Southern grid of about 49 GW capacity is interconnected through a number of HVDC systems. However, to cater the imbalance between demand and supply in the region, National Grid of 23,800MW capacity through inter-regional links were established for exchange of power between regions. A view of the present National Grid showing inter-regional lines is depicted at Fig. 2. Fig. 2 : Existing Inter-regional links of National Grid As per the Integrated Energy Policy: Report of the expert committee by Planning Commission, it is estimated that by 2027, demand would be about 522GW (considering 9% GDP growth rate) for which total installed capacity of about 685GW is envisaged. Growth pattern of capacity requirement by the end of each five(5) years by 2027 is given at Fig GW Fig. 3: Growth pattern of capacity requirement by

4 In order to enhance the capacity of inter-regional links to enable transfer of power across regions in long-term, National Grid capacity is being enhanced to more than 65,000 MW by A view of National Grid by 2017 is shown at Fig-4 NR KURUSHETRA JAIPUR FATEHPUR GORAKHPUR AGRA AURAIYA BALIA KANKROLI ORAI MUZAFFARPUR RAPP PATNA BIRPARA BARH KOTA RIHAND TILAIYA SILIGURI B'SHARIFF SAHU PURI GAYA MALANPUR MALDA SASARAM GWALIOR V'CHAL ZERDA J'PUR POOL ER DEHRI NAGDA KORBA CHAMPA D'GARH BUDHIPADAR UJJAIN WR POOLING JHARSAGUDA SIPAT RANCHI RAIPUR ROURKELA WR TALCHER BALIMELA CHANDRAPUR NER SALAKATI BONGAIGAON L. SUBANSIRI SHOLAPUR KOLHAPUR PONDA GAZUWAKA RAICHUR NARENDRA BELGAUM U.SILERU NAGJHARI SR KOLAR LEGEND POWERGRID LINES EXISTING UNDER CONST./ PLANNED 765 KV LINES 400 KV LINES 220/132 KV LINES HVDC B/B HVDC BIPOLE Fig. 4: A view of National Grid by CONCERNS IN TRANSMISSION SYSTEM DEVELOPMENT Pocketed generation resources and wide spread load centers across the country coupled with right-ofway problems necessitates development of high capacity transmission corridors. However, major concerns towards planning of such corridors are : Long-term planning keeping a horizon of years Right-of-Way(ROW) and protection of flora and fauna Flexibility to enhance the transfer capacity in view of uncertainty of generation projects, implementation in different phases Optimisation of transmission cost and losses Non-discriminatory Open Access To fulfill above requirements, need of the hour is to introduce emerging technologies into the transmission system. In this direction, many new technologies have already implemented/undertaken. Some of them are: 765kV System with double circuit configuration as high power intensity corridor ±800kV 6000MW long distance HVDC system Multi ckt towers to avoid deforestation and protection of wild life Multi-conductor Bundle line to increase power intensity Compact Tower /Pole Tower to reduce Right-of-Way in urban area High Temp endurance conductor line for increased loading Fixed and Thyristor Controlled Series Capacitor (TCSC) to enhance transmission capability Gas Insulated substation (GIS) to optimise space for substation Substation automation & remote operation to reduce land requirement 4

5 In addition, 1200kV AC technology is being developed as next higher AC voltage in the country, which is the highest AC voltage level in the world. Development of this technology would go a long way for strengthening of National Grid capacity to take care of long-term power transfer requirement of the country. In order to develop this 1200kV AC technology indigenously, a unique effort has been made, which is first time in India Power Sector, through an open collaborative effort between POWERGRID and manufacturers to establish a 1200kV UHVAC Test Station at Bina. This endeavor shall benefit Indian Power sector and manufacturers as availability of 1200KV class equipment within country will not only enable optimisation of transmission cost, but also help in making ease in execution and O&M phase. One 1200kV single circuit transmission line with octa-bundled configuration of about 400km long is under implementation which shall be initially to be operated at 400kV quad-bundled double circuit line. In this direction, POWERGRID along with 34 manufacturers is establishing a 1200kV UHVAC Test Station at Bina. It contains two nos. 1200kV bays comprising 1200kV class equipment like Instrument transformers, Circuit Breakers and surge arresters and two nos. of 1000MVA transformer bank each comprising three(3) single phase 400kV/1200kV, 333 MVA auto transformers. In addition to the above substation equipment, two(2) nos. 1200kV AC test lines about one(1) km. long [one single circuit(s/c) and one double circuit(d/c)] each will also be constructed and charged through these two 1200kV bays to study their performance by conducting measurements of various line parameters. In the existing 400kV system through a Loop-in loop-out (LILO) arrangement, power flow through 1200kV test station shall be established. Schematic of 1200kV National Test Station is presented at Fig kV line 400kV line Satna line 400kV Bina Bus 1200kV line 1200/400kV Transformer 1200/400kV Transformer To 400kV Satna line Fig. 5: Schematic of 1200kV Test Station arrangement Nominal voltage considered as 1150kV with maximum level at 1200kV, LIWL of equipment considered as 2400kVp and SIWL as 1800kVp. Multi Column Surge Arresters have been developed to achieve lower ratio of Lightning and Switching Impulse voltage. The test station is expected to be charged in the first quarter of UNCERTAINTIES IN TRANSMISSION SYSTEM PLANNING In the current electricity supply regime, various uncertainties are associated with transmission system development process. Some of the key uncertainties pushing a paradigm shift in transmission system planning are : Uncertainties in development of generation project time frame No firm beneficiaries at the development stage of the project due to introduction of power purchase through tariff based competitive bidding process Recovery of investment towards transmission development 5

6 4.1 Uncertainties in development of generation project A large number of generation projects are proposed mainly in Orissa, Jharkhand, Chhattisgarh, M.P by private developers in 12 th Plan. All the developers have applied for long-term access for transfer of power from the projects. Past experience reveals that most of the time there is a big gap in planned and actual generation addition, which hampered the optimal utilization of overall planned transmission system as well as impacted in system operation. On the contrary, to address the RoW issue, it is necessary to develop high capacity transmission corridors from resource areas (generation complexes) to the load centers keeping in view long-term perspective. Proposed approach: It is important that most of the projects in the particular generation complex must get materialized as per the schedule to ensure optimal utilization of transmission infrastructure. For this, an integrated resource planning approach is required so that a particular complex gets materialized first. Further, as the generation projects are developed in phases, flexibility in upgradation of transmission corridor matching with its phase-wise development through integration of new technologies may be adopted to take care of uncertainty and optimize investment. This shall also facilitate smooth operation of system in terms of maintaining grid parameters, stability etc. 4.2 Uncertainties in identification of beneficiaries Earlier the projects were planned as a regional generation projects (Inter-State Generation System), in which all the constituents of a particular region were the beneficiaries or at least beneficiaries were known upfront. Accordingly the transmission system was planned based on the requirement of power transfer to the known destinations. However, to promote competition in the electricity supply industry, Govt. of India has issued guidelines for determination of Tariff by Bidding Process for Procurement of Power by Distribution Licensees. Due to introduction of such tariff based competitive bidding under Case-I/Case-II guidelines, generation developers don t have conformity from the beneficiary till they win the bid from distribution licensees. Therefore, at the time of long-term access application, no firm beneficiaries are identified. Therefore, in this scenario, generation developers are not able to commit upfront about the beneficiaries along with their allocation for the purpose of planning optimal transmission system. Further, development of number of Merchant Power Plant(MPP) have been envisaged and in such cases also by its nature there is no firm beneficiaries. In such scenario, it has become difficult to plan the transmission system in the absence of information about the beneficiaries and quantum of drawl by each of them. Proposed approach: National Electricity Plan envisaged future demand supply scenario of various regions and Electric Power Survey report provides demand projection of different States. Further, based on the capacity addition programme in the State, future surplus-deficit situation may be estimated. Accordingly, developers may inform the target beneficiary(ies)/regions for power transfer from the respective projects while evolving transmission system fitting into overall transmission plan. In the long-term access regulation of Central Electricity Regulatory Commission(CERC) such provision of indicating target region has been kept now. 4.3 Recovery of investment for Transmission system Uncertainties in generation project schedule and firm beneficiaries, project development in a few complexes, development of high capacity transmission corridors to take care of right-of-way issue etc, has resulted into complexity in recovery of investment in transmission corridors. In case only few generation projects materializes, the cost of transmission for the corridor would be high. On the other hand, as mentioned earlier, generation developers are also not sure about the firm beneficiary and therefore, may be reluctant to share of transmission charges for a particular transmission corridor. This has made the overall transmission system planning and development further difficult. 6

7 Proposed approach: In order to rationalize the transmission charges of various corridors to take care of uncertainties and recovery of investment, it is proposed that transmission system of various private generation projects/mpps may be planned and segregated into two parts: Part-A: Portion of transmission system between generation project and grid interconnection point/pooling station (Inter-state Transmission System) as dedicated transmission system of specific project. Further, being dedicated element, same may be built, owned, operated and maintained by the respective developer/tariff based bidding route and cost to be borne by the particular generation developer. Part-B: Portion of transmission corridor beyond the grid interconnection point/pooling station may be developed as a common purpose system to be utilized by other projects also and same to be treated as part of common system strengthening. Transmission charges are to be pooled with the Regional Transmission system and considered in the Point of Connection(PoC) charges comprising of point of injection and drawal charges. Regulatory approval may be obtained to include the asset in the common pool. However, to ensure timely development of common purpose transmission corridor(s) in an environmental friendly manner, it is proposed that respective generation developers may share the transmission charges to provide comfort for the investment to the transmission developers. The generation developers in turn may make back-to-back arrangement with the procurers/beneficiaries for transmission charges recovery. 5.0 CASE STUDY As discussed above, capacity addition of about 75GW in 12 th Plan (Central sector-24%; State sector- 18% and Private-58%) has been envisaged which includes proposed IPP generation projects mainly in Orissa, Jharkhand, Chhattisgarh, Madhya Pradesh etc. with capacity about 40,000 MW. In most of the cases, firm beneficiaries of the IPPs are not known and only target beneficiaries or destination of power transfer requirement is available. This has cropped up plethora of uncertainties and challenges to the transmission planning and development process. Absence of information about beneficiaries from such large sized projects of Private /Merchant developer as well as firm schedule of generation projects would need to make some assumption regarding destination of power transfer to plan the high capacity transmission system. As per National Electricity Plan/18 th Electric Power Survey report, scenario emerged that power would primarily need to be transferred to deficit regions like Northern/Western region. However considering the severe Right-of-way constraints in States like Chhattisgarh which has about 50% dense forest/reserve areas and of the similar order in the States of Jharkhand and Orissa as well as bulk quantum of power transfer requirement from the generation complexes in these states, it is required to develop high intensity transmission corridors(mw/m ROW) with voltage level 800kV/1200kV. A comparison of power intensity at different transmission voltage level is given at Table-1: Table-1: Power Intensity(MW/m) at different transmission voltage level 400kV 765kV ±800kV HVDC 1200kV ROW(m) Capacity(MW) MW/m It is seen that power intensity(mw/m ROW) of 765kV transmission corridor is about 3 times higher than 400kV level. Further, intensity of ±800kV 6000MW HVDC/1200kV corridor is about 5 times higher than 400kV and almost double than 765kV corridors. A comparison for requirement of number of transmission corridors at different voltage level for transfer of about say 8,000MW power satisfying n-1 redundancy criteria is presented in Table-2 7

8 Table-2: Transmission Corridor Requirement Voltage level No. of Transmission Corridors Approx. min Right-of- Way required(m) 400kV AC D/c kV AC S/c kV AC D/c kV AC ±800kV 6000MW HVDC It is observed that for transfer of about 8,000MW at 765kV level, there is a requirement of at least 4 nos. transmission corridors (S/c) which requires about 250 meter Right-of- way. Keeping this in view, it is the need of the hour to adopt higher voltage level as well as high intensity corridors such as ±800kV, 6000MW HVDC system, 765kV double circuit(d/c), 1200 kv AC(initially may be operated at lower voltage level when power transfer requirement is less) etc. so as to utilize Right-of-way in an optimal manner. As per the information, complex wise proposed capacity addition in the Orissa, Jharkhand, Chhattisgarh, Madhya Pradesh by is shown in Table-3. Table-3: Complex wise capacity addition envisaged State/Complex Capacity(MW) Orissa 10,000 Jharkhand/West Bengal 4,500 Madhya Pradesh 4,500 Chhattisgarh i) Raigarh 11,000 ii) Champa 10,000 Power from the above generation complexes is envisaged to be transferred to different target beneficiaries in Western/Northern Region. Keeping this in view a composite but flexible transmission system was evolved based on the load flow studies. In the studies, entire transmission network of Eastern, North-eastern, Western, Northern grids corresponding to 12 th plan time frame was simulated and complex wise corridors are discussed as below. 5.1 Raigarh Complex In order to facilitate transfer of power from generation projects in Raigarh complex, Chhattisgarh in Western Region, development of a 400/765kV Pooling station near Raigarh is proposed so that power of all the upcoming IPP projects in this complex can be lifted at the pooling stations. For onward dispersal of power, this Pooling Station is proposed to be connected with another pooling station near Raipur. Considering serious ROW constraint beyond Raigarh/Raipur and quantum of power transfer, it was proposed to interconnect Raigarh and Raipur through high capacity 765kV D/c lines. In addition, keeping in view serious ROW constraint and quantum of power transfer beyond Raipur, it was proposed to develop a parallel 765kV D/c high capacity transmission corridor through Raipur- Wardha-Aurangabad in parallel with Wardha Aurangabad 1200kV corridor(initially to be operated at 400kV level). This 765kV D/c corridor is the first of its kind in Indian Power System. 5.2 Champa Complex Similarly for transfer of power from Champa complex in Chhattisgarh, it was proposed to develop a 765/400kV Pooling Station and ±800kV HVDC terminal near Champa to interconnect the nearby IPP projects. Considering the quantum of power transfer requirement and ROW issues, a hybrid high capacity AC & HVDC system is considered. High capacity AC corridor emanating from Champa Pooling Station i.e, Central Part of Chhattisgarh and terminating in Western Part of Maharashtra. This pooling station is also proposed to be interconnected with Raigarh Poooling station thorugh 765kV link for mutual support in power evacuation. Further, in view of the bulk power transfer requirement 8

9 towards Northern region(nr) beneficiaries, a ±800kV, 6000MW HVDC bipole upto Kurushetra in NR is proposed. A schematic of the different high capacity transmission corridors in Western Region is shown at Fig. 6 Fig. 6: Schematic of High capacity transmission corridor in WR for IPPs in Chhattiagarh/M.P 5.3 Orissa/Jharkhand Complex As indicated by the generation developers, the major portion of power from various generation projects of Orissa/Jharkhand would have to be exported to power deficit regions like NR & WR. For evacuation and transfer of power from projects in Orissa/Jharkhand to NR/WR, there was a need to evolve a composite high capacity transmission scheme in view of the Right-of-way problem, wherein different generation projects coming up in different time-frame could be integrated. In order to pool power from various generation projects in Orissa, two(2) nos. of 765/400kV pooling substations have been planned at Angul and Jharsuguda. The pooling stations would be interconnected in ring form with 765kV lines. For transfer of power from Angul/Jharsuguda to WR/NR, a high capacity 765kV AC D/c corridor has been planned to NR via WR and ER. The corridor emanates from Jharsuguda in ER, reaches upto Bhiwani in the western part of NR via important substations like Dharamjaygarh(WR), Jabalpur(WR), Bina(WR), Gwalior(WR) and Jaipur(NR). The corridor also reaches to Indore, northern part of WR via Bhopal(WR) and Jabalpur(WR). In the process three(3) nos. of new 765/400kV substations would be created at Dharamjayagarh, Jabalpur and Bhopal. Dharamjayagarh would be an important power hub where power could be pooled from generation projects of Orissa as well as Jharkhand/Bihar in ER for onward transfer to Western part of WR as well as to NR. Jabalpur 765/400KV substation would be an important take off point for diversion of power to WR through Jabalpur-Bhopal-Indore route and to NR via Jabalpur-Bina-Gwalior(WR)-Jaipur(NR)-Bhiwani route. The corridor in the central part of NR extended at Kanpur/Lucknow, central/northern part of NR via ER. A schematic of the High Capacity Transmission Corridor for IPP projects in Orissa is depicted at Fig. 7. 9

10 Fig. 7: Schematic of High capacity transmission corridor for IPPs in Orissa/Jharkhand 6. RECOVERY OF INVESTMENT Towards recovery of investment in high capacity transmission corridor, it was decided that immediate evacuation system i.e. dedicated transmission system between generation project and Pooling Station/grid connection point for different generation projects shall be developed by the respective generation developers. However, the common transmission corridor to facilitate power transfer to target beneficiaries would be developed as Inter-State Transmission System in phases matching with the commissioning schedule of generation developers. Further, as the transmission corridors were identified based on the target beneficiaries/allocation, hence, developers agreed to share the transmission charges for particular corridor in proportion to their transfer requirement for smooth development of system. Central Transmission Utility(POWERGRID) was also accorded regulatory approval from CERC to undertake implementation of above high capacity transmission corridors keeping in view the progress of he generation projects. 7. CONCLUSION Tremendous growth of Indian Power sector in all fronts viz. generation, transmission and distribution is taking place. National Grid capacity is being enhanced from present level of 23,800 MW to more than 65,000 MW by 2017 which shall be further increased progressively. Large capacity addition was envisaged through IPPs/MPPs mainly confined in Orissa, Jharkhand, West Bengal in Eastern Region, Chhattisgarh and M.P in Western Region. However, various uncertainties are associated with above IPPs specially no information about firm beneficiaries, commissioning schedule of projects, recovery of investment in transmission etc. This made the transmission system planning and development a challenge. Development of high capacity transmission corridors comprising HVDC and AC system interconnecting various generation projects through suitable pooling station to major load centres in power deficit Western/Northern Region based on target beneficiaries were proposed. Further, to rationalize transmission charges, proposed transmission system was divided into generation specificdedicated system to be developed by the respective developer(s) and common purpose system as a system strengthening project in which transmission charges also to be shared by the generation developers corresponding to their capacity for smooth development of system. 10

11 ACKNOWLEDGMENT Authors are thankful to the management of POWERGRID for granting permission to present the paper. Views expressed in the paper are of authors only and need not necessarily be that of management. BIBLIOGRAPHY [1] Key inputs for accelerated development of Indian Power Sector for 12 th Plan & beyond, CEA Base paper, 2009 [2] Integrated Energy Policy-Report of the Expert committee, GoI, 2006 [3] Central Electricity Authority(CEA) Website: 11