Presentation on theme: "1 GUJARAT ENERGY TRANSMISSION CORPORATION LIMITED Grid related issues in case of Wind/Solar based Generation in Gujarat 07 th February, 2009 S. K. Negi."— Presentation transcript:
1 GUJARAT ENERGY TRANSMISSION CORPORATION LIMITED Grid related issues in case of Wind/Solar based Generation in Gujarat 07 th February, 2009 S. K. Negi Managing Director
2 Power Scenario in Gujarat as on 31.12.2008 Present power generating capacity including State sector, Private sector & Share from Central sector: 10417 MW. Sr. No. ParticularsCapacity in MW 1State Sector including Hydro4766 2Private Sector2418 3Central Sector3233 Total….10417 56% is generated from South Gujarat. 37% is generated from Central Gujarat. 7% is generated from Saurashtra and Kutch area. Out of total 10417 MW installed capacity, 63% is from thermal, 23% is from Gas, 7% from hydro and 7% from nuclear sources.
3 Future Power Scenario in Gujarat Sr. No. ParticularsCapacity addition during 11 th FYP in MW Capacity in MW 1State Sector including Hydro 17856551 2Private Sector56908108 3Central Sector20425275 Total….975219934 4After March-20123000 (1900 MW Private sector + 1100 MW Central sector) 22934 Total….1275222934 52% is generated from South Gujarat. 31% is generated from Central Gujarat. 27% is generated from Saurashtra and Kutch area. 4000 MW Mundra, UMPP is also located at Mundra in Dist: Kutch. Out of total 19934 MW installed capacity, 67% is from thermal, 26% is from Gas, 4% from hydro and 3% from nuclear sources.
4 Power Scenario in Kutch and Saurashtra Present installed capacity of Saurashtra and Kutch is as under: KLTPS, Panandhro, Kutch-215 MW GMDC, Akrimota, Kutch-250 MW GSECL, Sikka, Saurashtra-240 MW Total….-705 MW Proposed anticipated capacity addition in Saurashtra and Kutch during 11 th five year plan and subsequent years: KLTPS, Panandhro, Kutch (Unit-IV)- 75 MW Adani Power, Mundra, Kutch-2640 MW UMPP, Mundra, Kutch-4000 MW GSECL, Sikka Extension, Saurashtra- 500 MW Essar Power, Vadinar, Saurashtra-1200 MW GPPC, Pipavav, Saurashtra- 700 MW BECL, Bhavnagar, Saurashtra- 600 MW Total….-9715 MW In addition to this, in Western Gujarat itself the approved proposals for integration of Wind power are around 3600 MW.
5 Power Scenario in Kutch and Saurashtra The pending proposals for integration of Wind power are around 4000- 4500 MW. Also, a proposal for establishing concentrated solar thermal power project to the tune of 8000 MW in Kutch is in the conceptual stage. To summarise West Gujarat generation more than 25000 MW of which around 10500 MW will be from conventional sources and more than 14500 MW from renewable energy sources. West Gujarat alone cannot absorb this huge quantum of power or it can be rather said that the load of entire State may not reach this level. As per 17 th Electric Power Survey, published by Central Electricity Authority, New Delhi, projected load of Gujarat State is 14374 MW by March-2012.
6 Amendment in Wind Farm Policy 2007 The Government of Gujarat through GR No: WND 11–2008–2321–B dated 7th January 2009, has made amendments in the Wind Power Policy – 2007 notified earlier through GR No: EDA-102001-3054-B dated 13th June 2007. Wheeling of power to consumption site at 66 KV voltage level and above:- The wheeling of electricity generated from the Wind Turbine Generators (WTGs), to the desired location(s) within the State, shall be allowed on payment of transmission charges, and transmission losses otherwise applicable to normal Open Access Customer. Wheeling of power to consumption site below 66 KV voltage level. The wheeling of electricity generated from the WTGs, to the desired location(s) within the State, shall be allowed on payment of transmission charges, otherwise applicable to normal Open Access Consumer, and transmission and wheeling losses @ 10% of the energy fed to the grid. The wheeling of electricity generated by smaller investors, having only one WTG in the State, to the desired location(s), shall be allowed on payment of transmission charges, otherwise applicable to normal open access consumer, and transmission and wheeling losses @7% of the energy fed to the grid. Wind farm owner desiring to wheel electricity to more than two locations shall pay 5 paise per unit on energy fed in the grid to concerned Distribution Company in whose area, power is consumed in addition to above mentioned transmission charges and losses, as applicable The electricity generated from the WTGs commissioned from 1st April, 2009, may be sold to GUVNL and/or any Distribution Licensee within the state, at a rate of Rs. 3.50 per unit of electricity for the entire period of PPA. GUVNL and / or any Distribution licensee may purchase surplus power from WTGs wheeling power for their captive use after adjustment of energy against consumption at recipient unit (s) at a rate of 85% of tariff applicable to WTGs (commissioned in same tariff block) selling power to GUVNL and /or any Distribution licensee. GETCO is required to erect evacuation facilities beyond 100 kms between Wind Farm sub-station to GETCO sub-station As per the amended Wind Power Policy -2007, GETCO is required to collect Bank Guarantee @ Rs. 5 lacs per MW based on allotment of transmission capacity and in case the Developer fails to achieve Commercial Operation within the one year period in case of installed capacity up to 100 MW, two years in case of installed capacity from 201 MW to 400 MW and three years in case of installed capacity from 401 MW to 600 MW, the Bank Guarantee shall be forfeited by GETCO.
7 Summary of Wind farms in Gujarat Sr. No. DescriptionCapacity of Wind farm in MW KutchSaurashtraNorth Gujarat Total 1Wind farm capacity and connectivity approved 1120.40804.20--1923.60 a)Commissioned wind farm795.83551.75--1347.58 b)Wind farm to be commissioned 324.57252.45--577.02 2Wind farm capacity approved but work not completed by developer 148.001550.00--1698.00 3Total Wind farm capacity already approved (1+2) 1268.402354.20--3622.60 4Pending proposals1925.002335.00650.004910.00
13 Growing concern for the environmental degradation has led to the world’s interest in renewable energy resources. Wind is commercially and operationally the most viable renewable energy resource and accordingly, emerging as one of the largest source in terms of the renewable energy sector. Wind is the natural movement of air across the land or sea. Wind is caused by uneven heating and cooling of the earth’s surface and by the earth’s rotation. Land and water areas absorb and release different amount of heat received from the sun. As warm air rises, cooler air rushes in to take its place, causing local winds. The rotation of the earth changes the direction of the flow of air. This type of energy harnesses the power of the wind to propel the blades of wind turbines. These turbines cause the rotation of magnets, which creates electricity. Wind Energy
14 Wind Energy as a source of electricity has following advantages: Wind power produces no water or air pollution that can contaminate the environment, Power from the wind does not contribute to global warming because it does not generate greenhouse gases, Wind generation is a renewable source of energy, which means that we will never run out of it. Fuel source is free, abundant and inexhaustible, Extremely low operating cost, Less commissioning period, Creates employment, regional growth and innovation, Reduces poverty through improved energy access, It is very good as a fuel saver. Wind Energy
15 At the same time, wind has some peculiar characteristics : Wind is unpredictable; therefore, wind power is not predictably available. When the wind speed decreases less electricity is generated. This makes wind power unsuitable for base load generation. Limited control or no control on generation. Drastic variation in generation due to variation in wind speed. (As shown in the graph). Electricity produced by wind power sometimes fluctuates in voltage and power factor, which can cause difficulties in linking its power to a utility system. Because winds do not blow strongly enough to produce power all the time, energy from wind machines is considered “intermittent,” that is, it comes and goes. Thus, the average plant load factor of wind generators is very low to the tune of 15-20%. Therefore, utility companies can use it for only part of their total energy needs. Wind Energy
16 The maximum wind generation is available during monsoon / off- peak period of the year when the total system demand crashes by about 40-50% and it becomes very difficult for the load dispatcher to handle the system effectively. In other words, it can be said that the wind energy is available in abundance when not needed and not available when needed most. Wind energy being green power and excessively available in monsoon, the load dispatcher is compelled to back down even the cheaper, firm and reliable power from thermal and hydro power stations. Depends upon wind velocity. Geographical locations, potential of wind. Limited potential area. Proximity to the load centre. In Gujarat, Kutch & Saurashtra are identified has a good potential of wind energy. Wind Energy
17 Wind Farm Generation for year 2007-08 Month Nos. of WF Total Capacity of WF in MW Generation Share in KWh KWh exported by GEB Share of Electricity in KWh KVARh drawn by WF PLF Apr-07364577.0654628735421068646076668434035011.09% May-07376605.5659306906712284292946225666721221.32% Jun-07385634.0658901891226441188754501970194119.44% Jul-07391642.5159964371911828599525434839693121.51% Aug-07388627.765129965367180472129784895927277328.71% Sep-07436744.665537894636052115318425225936389.92% Oct-07442784.365277186955528832716581218871094.81% Nov-07444790.965426327397373564189538321988587.36% Dec-07447800.265111147009400316110746693560181519.22% Jan-08457886.545116619170273686116345484525547318.23% Feb-08464955.079808680044821697638584465897014.20% Mar-085321185.145122875316646763122228553586469014.32% Total427.167769.49961030853611456112710262924846643976015.23%
18 Wind Farm Generation for the year 2008-09 Month Nos. of WF Total Capacity of WF in MW Generation Share in KWh KWh export ed by GEB Share of Electricity in KWh KVARh drawn by WF PLF Apr-085331190.745104559255302460104256795369699112.16% May-085341197.3953009607101336293008270811492860534.89% Jun-085381238.6553141879282419933139459351865151435.20% Jul-085331234.2552707445152144702705300451850240030.44% Aug-085371242.2552430552823649942426902881305089027.13% Sep-085481346.505170767145724145170043000498223617.54% Oct-085491351.2055704708012063315584074916276605.74% Nov-085491365.3051286617531081498127580255458824012.98% Dec-085501380.305176665649718690175946959639236717.70%
31 There are number of unresolved technical, institutional and regulatory questions concerning distributed generation in general and wind generation in particular. On the technical level, major barriers are.. Novelty and unfamiliarity of distributed technologies. Lack of substantial field experience with these technologies. Costs and complexity associated with thorough engineering evaluations. Weak evacuations network as well as onward transmission networks. Less availability of evacuations corridors. Less consumptions in local area due to wide variation in load due to variable load in agriculture, less and variable industrial demand and low demand on staggering day. Variable local load pattern leads to overloading of transformers and main transmission lines which requires high capacity of strengthening of transmission network. Average PLF observed 15-20% which leads to inefficient occupation of transformer capacity and non utilization of infrastructures. Integration with grid
32 Electrical power grid is an unique one in which generation and demands are balanced instantaneously and continuously. Fluctuations in power consumed by the consumers and variations in uncontrolled generators are compensated by the controlled generators. When generation equal to load, frequency operates at 50 Hz. Variation in frequency indicates rise of load or generation vice versa is term as a balancing. In the grid system, it is not necessary for compensating each and every variation from individual consumers / generators. Only aggregate variation in the control area is balanced. Aggregation is the powerful tools with the power system operators. When wind power plants are introduced into the power system, an additional source of variation is added to the already variable nature of system. Electrical grid
33 Load-Generation balance In large interconnected system, load generation is reflected with change in tie line flows. In a small system, load generation balance is reflected with variation in frequency. Variation in frequency is limiting factor for capacity addition of the wind farms. In predominantly hydro and gas generation system with good ramp rate will be positive factor, helping for compensating variation of wind generation.
34 Balancing Balancing in power system occurs over wide time frames: Years in advance : Enough generation has to be planned and built so that there is sufficient capacity available to meet load requirements Day Ahead : Select which available generator can reliably meet expected requirements at lowest cost. Real Time : Real time balancing can be obtained by two different methodology: Load Following (Backing down) Load Regulation (Load Shedding)
35 Balancing by Load Following Load following requirement are highly correlated …. 24 hours power supply to rural under JGY scheme. 24 hours power supply to urban area. 8 hours committed agriculture supply in various groups. High demand during summer due to domestic & commercial cooling load. High demand agriculture demand during Ravi crop. Demand variation due to festival & seasons. Load demand during morning & evening peak.
36 Balancing by Load Regulations Load Regulation requirement are correlated by…. Availability of generation on bar. Ramping rate of generating stations. Variable cost of generating stations. Technical Minimum of generating stations. Peak and off peak demand, required generation to be kept in reserve. The random variation in demand OR generation is adjusted instantaneously by primary response generators.
37 Grid operation with Wind Generation Scenario 1: An increase in load along with increase in wind generation OR drop in load along with drop of wind generation – Additional generation required for frequency maintenance is less. System Operator: It is a safe operation for grid operators. Most favorable condition for grid operators. During evening peak, maximum wind energy available and it helps to meet peak demand.
38 Grid operation with Wind Generation Scenario 2(A) : A drop in load along with increase in wind generation. System Operator: Backing down of other generators. High Voltage problem and switching off lines. System operation with critical loading. If local load is very low, overloading of associated transmission lines.
39 GETCO grid operation with Wind Generation Scenario 2(A) : A drop in load along with increase in wind generation. System Operator: When load is very low and wind generation is maximum, system operator has to back down cheaper generation at Panandhro and Akrimota to control loading of 220 KV Sivlakha- Morbi line. In case of contingency of tripping of either Morbi-Sivlakha OR Anjar-Deodar OR Sivlakha-Sankhari lines, total generation at Panadhro and Akrimota affected badly. In Kutch area, due to high wind energy generation, voltage remains high causing frequent failure of lines disturbing parameters while synchronizing, delaying in synchronization.
40 Grid operation with Wind Generation Scenario 2(B) : An increase in load along with drop in wind generation. System Operator : Increasing load along with decrease in wind generation is a very critical nature of situation for system operator. Additional generation is to be brought into system very quickly. If no generation available, heavy load shading to be resorted. If frequency permits, overdrawl at that prevailing rate. Requisition of costly generation i.e. on SPOT gas, Naphtha if available Remedies : Additional generation capacity is required for maintenance of load generation balancing especially gas based and hydro based.
41 Power Quality with Wind Generation Generally it is believed that with increase in wind generation, the power quality suffers. Main power quality problems are: oVoltage Regulation, oHarmonics. Old WTG machines with induction generators have not been required to participate in system voltage regulation. Their reactive power demand are compensated by switched shunt capacitors. New WTG machines with variable frequency drives have inherent control of reactive power output and can participate in voltage regulation. If wind farm is far from generation source, high voltage witnessed near to wind farms with increase in wind generation. The variable frequency generators in WTGs use AC-DC converter for connection with Grid, which increases the Harmonics level in the system.
42 Wind Penetration Energy penetration is the ratio of the amount of energy delivered from the wind generation to the total energy delivered. For example, if 200 megawatthours (MWh) of wind energy is supplied and 1,000 MWh is consumed during the same period, wind’s energy penetration is 20%. Capacity Penetration is the ratio of the nameplate rating of the wind plant capacity to the peak load. For example, if a 300-MW wind plant is operating in a zone with a 1,000-MW peak load, the capacity penetration is 30 %. The capacity penetration is related to the energy penetration by the ratio of the system load factor to the wind plant capacity factor. Say that the system load factor is 60% and the wind plant capacity factor is 40%. In this case, and with an energy penetration of 20%, the capacity penetration would be 20% x 0.6/0.4, or 30%. Instantaneous penetration is the ratio of wind plant output to load at a specific point in time, or over a short period of time.
43 Conclusion If the share of wind generation instantaneous penetration at any point of time is excessively high compared to the total system demand, then, following new operating methodology need to be adopted for ensuing reliability and stability of system: –Methodology for accurate long term & short term forecasting. –Real time data from wind farm to system operator to be made available for effective grid operation. –Reserve capacity with high ramp up generators such as a hydro and gas shall be kept. –All wind energy generation be brought under regulations of ABT which means elimination of generation in case of high frequency or system constraints. –Reinforcement of main transmission network and power corridors. –Augmentation and reinforcement of voltage regulating equipments such as reactors, switched capacitors including FACTS devices.
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