1. Integration of Renewable Energy
P.R.Raghuram
GM, SRLDC

2. Outline of this presentation
Introduction
Basics of Renewable Technologies
Scenario of Renewable Energy generation in India
Issues involved in Grid Integration of RE:
International Experience
The Road ahead

3. Outline of this presentation
Introduction
Basics of Renewable Technologies
Scenario of Renewable Energy generation in India
Issues involved in Grid Integration of RE:
International Experience
The Road ahead

4. The future depends on what we do in the Present….Mahathma Gandhi

5. Drivers for Alternate energy sources
Oil crisis in 1970s
Dwindling/ limited natural Resources (Oil, Coal)
Energy Security
International mandate for development of CDM technologies and to reduce Carbon/ Sulpher/ Green House Gas emissions, phase out fossil fuel generation and develop alternate Energy sources
IPCC (Intergovernmental Panel for Climate Change) under UNEP(1998)
UNFCCC Rio De Janeiro 1992
Kyoto protocol 1997
Copenhagen Summit 2009
Indian initiatives
NAPCC (National Action Plan for Climate Change)
JNNSM (Jawaharlal Nehru National Solar Mission)

6. Outline of this presentation
Introduction
Basics of Renewable Technologies
Scenario of Renewable Energy generation in India
Issues involved in Grid Integration of RE:
International Experience
The Road ahead

7. Various types of Renewable Energy
Wind
On shore
Off shore
Solar
Solar PV (Photo Voltaic, Concentrated PhotoVoltaic)
Solar Thermal (Solar Concentrated, Parabolic trough/dish, Fresnel collector, Heliostat & Solar Tower receiver, Solar updraft receiver)
Micro Hydel (upto 25 MW)
Biomass/
Bagasse (the dry fibrous waste that is left after sugarcane has been processed)
rice husk, cotton stalk, mustard stalk, groundnut shell, coconut fronds, waste cotton stalks, bark, roots of trees, cane trash, arecanut shells, Prosopis juliflora, poultry litter)
Co-generation
Municipal Solid waste
Geo-Thermal
Hydro kinetics
Tidal power
Wave technology

8. Power vs Wind speed for a typical Induction type WTG
where ρ= wind density, Cp is Power Co-efficient of Wind Turbine, λ is tip speed ratio, θ is the blade pitch angle, Ar = area of wind incidence on blades, v= wind speed
Source:

9. Fixed Speed/ Induction type Wind Turbine Generator

10. Variable Speed type Wind Turbine Generator

11. Types of Wind Generators [1, 2, 3, 4]
Squirrel Cage
Doubly Fed
Direct Drive
Induction
Induction
Synchronous
Simple and Robust
Less mechanical stress
Less mechanical stress
Less expensive
Less noisy
Less noisy
Electrically efficient
Aerodynamically efficient
Aerodynamically efficient
Standard generator
Standard generator
No gearbox
Small converter
Aerodynamically less
Electrically less efficient
Electrically less efficient
efficient
Gearbox included
Gearbox included
Large converter
Mechanical stress
Expensive
Expensive
Noisy
Complex, heavy and
large generator
Oct. 2006
CREDP - Wind Farm Operation and Grid Integration 10

12. Electrical Characteristics of WTG
Reactive requirement:
Fault Ride Through (FRT) /Low Voltage ride-through (LVRT)
Governor operation available in WTG?
Inertia contribution to Grid?
Short circuit contribution
Can WTG be Black Started?
Distributed Generation Systems reduce burden on
Tranasmission system and reduce Losses

13. Increase in capacity and efficiency: Development of turbine technology
appr.20,00,000 kWh
160 m
Increase in capacity
In a mere 20 years, the yield
Of wind turbines has increased 100-fold.With the new 6 MW Turbines,
It will multiply another fivefold.
2010
6.000 kW
170 m 13

14. Criteria for Site Selection
SITE SELECTION – PLAIN TERRAINS
SITE SELECTION – HILLY TERRAINS
High annual average Wind Speed ( > 7 m/sec.)
Wind Structure at The Proposed Site
Altitude of the proposed site.
Nature of Ground (soil for proper foundation / civil work ).
Favorable environmental condition to prevent corrosion & not prone to cyclone.
Availability of electrical infrastructure for evacuation of electricity generated .
2.5 D

15. CSP - TOWER TECHNOLOGY
CSP - TROUGH TECHNOLOGY
CSP - DISH TECHNOLOGY

16. Typical arrangement of an Small Hydro Power station
SHP station on a river
SHP station on a canal

17. Outline of this presentation
Introduction
Basics of Renewable Technologies
Scenario of Renewable Energy generation in India
Issues involved in Grid Integration of RE:
International Experience
The Road ahead

18. WIND ENERGY HARNESSED Source : MNRE
SR Maximum Wind AT 18:59 HRS
% of Wind in SR I/C – 17%
% of Wind Gen in SR Demand Met – 14.9 %
% of Wind in TN I/C – %
% of Wind Gen in TN Demand %
Capacities in MW as on
Inst. Cap.
Potential
Wind Power
13066
48561
Small Hydro Power
2939
14292
Biomass Power
997
8680
Bagasse Cogeneration
1562
5000
Waste to Power (Urban & Industrial ) 72
7000
Solar Power (SPV) 18
200000
Total
18654
283533
WIND ENERGY HARNESSED
Source : MNRE 18

19. Wind Power Potential 19

20. Map showing Solar radiation across India20

21. Potential Capacity of RE Sources Statewise
Wind
SHP
Biomass
Andhra Pradesh
8968
552
830
Arunchal Pradesh
1333
Chattisgarh
Gujarat
10645
916
Haryana
110
Himachal Pradesh
2268
Jammu & Kashmir
1411
Karnataka
11531
643
859
Kerala
1171
Maharashtra
4584
762
1711
Madhra Pradesh
1019
400
1059
Nagaland
28.67
Punjab
390
Rajasthan
4858 63
1289
Tamilnadu
5530
1186
Uttaranchal
1609
West Bengal
450
Total
48756
8680 21

22. Both Solar and wind concentration are geographically same
Solar Map
Wind Map
Both Solar and wind concentration are geographically same 22

23. Diurnal patterns
S-W monsoon
N-E monsoon
Seasonal patterns

24. Integration issues of Wind

25. Integration issues of Wind
Planning criterion for RE
Variability and Intermittancy
Forecasting and Scheduling
SCADA / telemetry
Network related Problems and Congestion
Protection
Commercial mechanism implementation

26. Planning Transmission system for RE
Initially wind as an energy rather than capacity addition
As the penetration of the wind increases, Wind treated interms of MW capacity
Network development and O&M
upto the pooling station by the wind developer
beyond the pooling station by the Distribution licensee
N-1 criterion to be maintained

27. Planning Transmission system for RE
Criteria used for Tr. Planning of Conventional power to be upgraded for RE
Studies for power flow, time-domain and small-signal stability along with short-circuit duty analyses tools
Trade off between network optimal utilization and redundancy
Dynamic Line Rating : During high wind periods the network can be loaded to a higher levels of thermal ratings of the network because of higher heat dissipation due to wind. This concept is called dynamic Line rating.
Diversity Factor :
Wind farms are usually located across large geographical spreads, hence wind pattern for all the wind mills and wind farms is not the same, thus the wind production at a given point of time is not same for all the wind generators and farms. This is called Diversity factor and is to be duly factored while designing evacuation systems.

28. Planning criterion for RE
Outage of wind generator should be planned during lean wind season, outage of solar, if required during the rainy season and outage of run-of-the-via hydro power plant in the lean water season.
50Hz
Load
Generation
Time frame
Planning criterion
1 -30 years
transmission and resource adequacy assessments.
1 year- 1 month
New capacity addition, Tr. Adequacy assessment
1 day- 1 week
Wind forecast, Demand forecast, Congestion monitoring, Market operations,
Minutes - hour
Wind forecast, Demand forecast, Unit Commitment and L-G balance
Seconds-to-minutes
Protection, AGC, Governor, Excitations systems, PSS, AVRs, SPS, FRT capability

30. Integration issues of Wind
Planning criterion for RE
Variability and Intermittancy
Forecasting and Scheduling
SCADA / telemetry
Network related Problems and Congestion
Protection
Commercial mechanism implementation

31. TN WIND GENERATION (28% of Energy)
Intermittancy: not continuously available
Variability : variable in magnitude
Uncertainity : Variations may not be as Expected
SR Maximum Wind AT 18:59 HRS
% of Wind in SR I/C – 17%
% of Wind Gen in SR Demand Met – 14.9 %
% of Wind in TN I/C – %
% of Wind Gen in TN Demand %
TIME →
Data taken from SCADA 31 31 31

32. KARNATAKA WIND GENERATION
Karnataka can better manage variability due to Hydro
as penetration increases, Difficult to manage
TIME →
Data taken from SCADA 32 32 32

33. TN WIND GENERATION MUs
Data are as received from TN 33 33 33

34. Impact of Variability on Home state
Wind generation typically varies from 800 to 2000 MWs.
Increased requirement of spinning reserve
Dip the system frequency due to absence of spinning reserve
Increasing the spot market cost of power
Host state having to resort to massive load shedding
Additional costs of dispatch of Liquid generation to offset the drop in RE generation
Any committed export through bilateral open access contracts can not be revised adding to the voes of the host state.
Burden of Frequency Support Ancillary services
Sudden Increase in RE generation- Thermal Gen backing down has limitations

35. DEALING WITH WIND VARIABILITY
SPINNING RESERVE/ON CALL HYDRO
ESTABLISHED METHOD IN MOST COUNTRIES
ADDITIONAL SPINNING RESERVE MANDATED WITH INCREASED PENETRATION
WHO BEARS THE COST?
HYDRO AS HEDGE
PUMPED STORAGE
DINORWIG IN UK
KADAMPARAI,SRISAILAM INDIA
OPEN CYCLE GAS PLANTS
GRID INTERCONNECTS TO HARVEST DIVERSITY
FUTURE -STORAGE 35

36. Integration issues of Wind
Planning criterion for RE
Variability and Intermittancy
Forecasting and Scheduling
SCADA / telemetry
Network related Problems and Congestion
Protection
Commercial mechanism implementation

37. Need for Accurate Forecasting
Maintain Load Generation balance
Increasing penetration of RE
Absence of spinning reserve
Perennial deficits in Generation
Effect of Higher Intermittency of RE
Thrust on Market participation of RE
Ensure level playing field to Buyers of RE
Favorable policy to RE vis-à-vis Accountability of RE gen
Forecasting with minimum accuracy of 30% for wind and 20% for Solar – IEGC mandate
Day ahead forecast for 15 min time blocks

38. Uncertainity in a narrow band, Hence it is possible to Forecast Wind generation

39. Align forecast with Scheduling granularity
How the Forecast is done?
Inputs : Meteorological data of Weather from satellites, Site topography, SCADA/
current data of weather, power, and historical data of weather and power
Earth surface divided into a grid of 35x70km and Earth’s atmosphere into 64 layers
The meso scale models further divide the data into 2.5 sq km or 0.5 sq.km grid
A digital model of Flow modelling, wake effect, and turbine output
Forecast methods are based on statistical techniques involving Numerical Weather
Prediction (NWP), Adaptive techniques, Time Series Anlaysis, Climatology.
Inputs are fed to different Suite of models which are distinctly based on An intelligent
model will combine the results of these individual models and gives a best fit of results.
The results are continuously fine tuned by taking real time data inputs from wind
farms on live updates of wind speed, live SCADA and site geography.
Output :The wind forecast is based on Forecast process is done upto 16 days ahead,
In the first 7 days it is run for 3 hour intervals while for the remaining period it run for 8 hour intervals.
On day ahead basis, it is run for 4 times for a window of 6 hours with a granularity of 10 minutes, which has to be ultimately aligned with 15 min average values.
The errors will be lesser and uncertainty band will be tighter for shorter forecast horizons.
Align forecast with Scheduling granularity 39

40. Flow Diagram of a Forecast model
NWP
Forecast
Suite of Models
Power
model
forecast
Model
adaptation
Wind speed
Historic
SCADA
Live
Adaptive statistics
Climatology
Time Series
Intelligent Model Combination
Optimised combination of NWP suppliers
Incorporation of mesoscale models
Regular live feedback from the wind farm
“Learning” Algorithms for:
Meteorology
Power models
Site
geography

41. Emphasis on Accuracy of Ramp Events
Comparison of Actual power with predicted Values
Emphasis on Accuracy of Ramp Events

42. Aggregating of Forecast
Geographic area-wise
Control Area-wise
Developer-wise
Windfarm wise
Seller-wise
Bilateral vis-à-vis Collective
4.i) of Complementary Commercial Mechanisms of IEGC Day ahead forecast: Wind/ power forecast with an interval of 15 minutes for the next 24 hours for the aggregate Generation capacity of 10 MW and above.
Mapping to Transaction-wise is important

43. Variability over a large Area is lesser
Single Turbine
A Windfarm
A Control Area
The forecast when aggregated on a larger
Geo-graphical area will give lesser errors 43

44. Forecast to be furnished to
Host Control Area
For Operational planning and
Real time Monitoring
RLDC
For Checking the Schedule Vs Actual
Forecast model to be adopted for Indian weather conditions
Special Emphasis on Ramp Events
Advance info on Forecast of Ramp Events to be given to System Operation at regular intervals and time horizons
Common Control centre for co-ordinating
with RLDC/ SLDC suggested

45. Forecast Data Flow to various functionalities
Real Time
Monitoring
Reserve
Balancing
Telemetry
Forecasting/
Scheduling
Trading

46. Need for Scheduling leads to……
Forecasting
Revising to minimise UI
Real Time monitoring (SCADA requirements)
Need to measure Actuals (Metering)
UI accounting (pool participation)
RRF

47. Scheduling applicability
Wind farms with collective capacity >= 10MW
Solar generating plants with capacity >= 5MW
connected at >=33 KV level
who have not signed any PPA with states/UTs/DVC or others
Nodal developer to be identified for co-ordination for SCDA, Metering, Scheduling, UI Charges, RRF etc.
Scheduling of RE w.e.f

48. How to accommodate Forecasted changes in Bilateral and Collective Schedules?
No Revision allowed in Collective schedules
Revisions upto a max 8 times in day ( 1 for each 3 hr time slot) allowed in bilateral
Revisions after a 6 time block notice
Treat Collective as Fixed and revise the Bilateral as per forecast changes
+ve changes : Easier to Manage
-Ve Changes : L-G balance and Frequency will be effected.
How to manage Ramp Events?

49. Intervals for Revisions of Intra-day Bilateral Trade Schedules
6 blocks notice
3 hours
3 hours
3 hours
3 hours
3 hours
3 hours
3 hours
3 hours

50. Why limit Sale under Collective transactions (Px) ?
Collective schedules can not be revised.
Real time Deviations due to fixed collective schedules to be factored for operational planning
Procedures for RRF mechanism :3.6. The concerned SLDC/RLDC will be responsible for checking that there is no gaming (gaming is an intentional mis-declaration of a parameter related to commercial mechanism in vogue, in order to make an undue commercial gain).

51. Px schedules can not be revised

52. Integration issues of Wind
Planning criterion for RE
Variability and Intermittancy
Forecasting and Scheduling
SCADA / telemetry
Network related Problems and Congestion
Protection
Commercial mechanism implementation

53. Telemetry is a must for scheduling and monitoring
IEGC mandates…
Wind farms shall have communication channel which is continuously available to system operator.
- Data Acquisition System facility shall be provided for transfer of information to concerned SLDC and RLDC
Telemetry is a must for scheduling and monitoring

54. SCADA and telemetry :
Due to dispersed and distributed nature of the wind generation across a large geo-graphical area, telemetering the data is a challenge
Real time data from wind turbines is metered and shall be transmitted to the local control centre of each wind farm.
The net injection of the wind farm is also measured at the pooling station and transmitted to the Area control centre (SubLDC), which in turn is re-transmitted to SLDC
As of now Only partial data is transmistted to SRLDC. Sometimes manually replaced data is sent

56. Reactive compensation of Wind farms can be utilised by Grid operator
Typical Windfarm Layout
VCB
33KV - Internal Lines
33KV - External Lines
Cluster-1
Cluster-2
Cluster-3 L1 L2 L3
Billing Meters
Transmission Grid
Grid Substation
WINDFARM
WINDFARM SS G1 G2
UTILITY SS
220 KV
132 KV
110 KV
66 KV
Local Loads
Reactive compensation of
Wind farms can be utilised by Grid operator 56

57. Integration issues of Wind
Planning criterion for RE
Variability and Intermittancy
Forecasting and Scheduling
SCADA / telemetry
Network related Problems and Congestion
Protection
Commercial mechanism implementation

58. Each Region
has to conduct
Studies to know
How much wind
can be
accomodated
Congestion anticipated after Kudankulam (2x1000MW) new IPPs in coastal TN and AP come up

59. Integration issues of Wind
Planning criterion for RE
Variability and Intermittancy
Forecasting and Scheduling
SCADA / telemetry
Network related Problems and Congestion
Protection
Commercial mechanism implementation

60. Protection requirements for RE :
Under-Voltage/ Over Voltage protection
Under frequency / Over frequency protection
Over current and earth fault protection
Load unbalance (negative sequence ) protection
Differential protection for WTG and grid connecting Transformer.
Capacitor bank protection

61. Protection requirements for RE :
Reactive Compensation (0.95 pf lag or lead)
Fault Ride Through (FRT)
Lightning protection of WTG system shall be according to IEC TR
Preferred configuration of the grid connecting transformer is delta connection on the wind farm side and grounded wye connection on the transmission system (grid) side to block the harmonics current and to detect the earth faults on the grid side .

62. Fault Ride Through / Low Voltage Ride Through (FRT/ LVRT)
WTG to stay connected to the grid during voltage dips caused by short-circuit one or all phase of its terminal current upto a specified voltage level. It is achieved through modifications of the turbine generator controls . This capability is essential as large scale trippings of Wind Turbines in large Wind farms result in disturbance in load flows. This should be achieved without damaging the WTG due to unbalance torque, Electronic and mechanical components.

63. Integration issues of Wind
Planning criterion for RE
Variability and Intermittancy
Forecasting and Scheduling
SCADA / telemetry
Network related Problems and Congestion
Protection
Commercial mechanism implementation

64. Commercial Options for RE Gen
Scheduling by ?
REC eligible ?
Cost
Revision in
Scheduling
Forecast
Reqd? 1
PPAs with home state( Preferential Tariff
By SLDC No
FIT ( as decided by SERC)
As per state policy
Required 2
Bilateral with an Intra-state buyer
Yes
Mutually negotiated 3
Bilateral with an Intra-Regional state buyer
By RLDC
Max once in 3 hrs. 1.5hrs notice 4
Bilateral with an Inter-Regional state buyer
By RLDCs
Max once in3 hrs. 1.5hrs notice 5
Collective transaction through Px
Price discovered thro’ Auction
Not allowed

65. Options for DISCOMs to fulfill RPO
What is RPO ?
Renewable Purchase Obligation specified by SERC. It will :
Incentivise the RE generator
Socialise the cost of variations by RE
Reduce the Geographical imbalances in RE spread

66. Options for RE generators
Prefrential Tariff
[State Regulated Tariff]
REC Option
Electricity
Green Attributes
Sale of electricity to Obligated Entities at State regulated tariff
REC
[Solar & Non-Solar]
Sale of Electricity at Market Price in open market
Sell to DisComs at Price ≤ Pooled Cost of Power Purchase*
Sale of RECs at Power Exchange
* - Weighted Average Pooled Price at which distribution licensee has purchased electricity (including cost of self generation, long-term and short term purchase) in the previous year, but excluding the cost of RE power purchase 66

67. REC Framework: Eligibility
Grid Connected RE technology approved by MNRE
Self
Consumption/
Captive use
Third party sale/Open Access
PPA with Distribution Licensee
No Promotional Wheeling
No Promotional Banking
No Electricity Duty Exempt
Sale at Mutually Agreed Price
PPA at Average Power Purchase Cost
PPA at Preferential Tariff
Eligible
Eligible
Not Eligible
Eligible if All Three conditions mentioned above are met
4/14/2017 67

68. Steps involved in REC mechanism
SERCs to specify Renewable Purchase Obligationat 5% in year 2010, increasing 1% every year for 10 years.
SERC to designate SA
CERC to designate CA
State Agency (SA) gives Accreditation of RE generator
Central Agency (CA) for Registration of RE and operate RE registry
Px for Price discovery
RE generators to apply for REC (within 3 months of generation)
SLDC to certify the RE generation
CA issues REC based on SLDC Certification (Solar and Non-solar)
RE can trade REC in either IEX or PxIL
One REC for 1 MWh of electricity injected (365 days from the date of issuance)
REC would be issued to RE generators only
REC mechanism is expected
to overcome geographical constraints
Facilitate effective implementation of RPO compliance,
reduce risks for local Discom,
reduce transaction costs
create competition among different RE technologies

69. Salient features …… Recognition
SERC to recognize REC as valid instrument for RPO compliance
State Agency
SERC to designate State Agency for accreditation for RPO compliance and REC mechanism at State level
Central Agency
CERC to designate Central Agency for registration, issuance of REC, repository for implementation of REC framework at national level
Only accredited project can register for REC at Central Agency
Non solar REC
(Rs/ MWh)
Solar REC
Forbearance Price
3,900
17,000
Floor Price
1,500
12,000 69

70. REC sale as on 30-03-11 Non-Solar Solar RECs issued 532 Nil Buy Bid
70377
30001
Sell Bid
Cleared Volume
Price discovered
3900/2225
-----
No. of participants 15

71. Outline of this presentation
Introduction
Basics of Renewable Technologies
Scenario of Renewable Energy generation in India
Issues involved in Grid Integration of RE:
International Experience
The Road ahead

72. World wide Wind Installed capacities
Country        
Inst. capacity (MW)
China
42,287
United States
40,180
Germany
27,214
Spain
20,676
India
13,065
Italy
5,660
France
United Kingdom
5,204
Canada
4,009
Denmark
3,752
As in 2010

73. GEMAS – a tool for RE integration computes Max. Admissible Wind Gen.
GEMAS carries out every 20 minutes 3-ph dead faults in the bus bars of 70 different substations.

74. Outline of this presentation
Introduction
Basics of Renewable Technologies
Scenario of Renewable Energy generation in India
Issues involved in Grid Integration of RE:
International Experience
The Road ahead

75. Storage Technologies to address variability
Pumped hydro storage
High Energy Battery storage
Storage Capacitors
Superconducting Magnetic Energy Storage (SMES)
Compressed Air Energy Storage (CAES)
Flywheel energy storage
Thermal Energy Storage
Smart Grid applications
Plug-in Hybrid Electric Vehicles (PHEV)

76. KADAMPARAI PUMP MODE ON 18-MAR-03
6MUs pumped 76 76

78. Need for develop Real time tools Assess Stability Limits
Conclusions
With Larger Grid interconnection The variability can be better handled.
With Forecasting, Operational planning can be better executed
With Scheduling accountability is induced
With REC mechanism and trading across seams, RE will be an attractive business
Retrofitting of old machines
Need for develop Real time tools Assess Stability Limits

79. Thank You