Integration of Renewable Energy P.R.Raghuram GM, SRLDC [email protected].

Integration of Renewable Energy

P.R.Raghuram

GM, SRLDC

[email protected]

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

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

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)

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

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: http://www.windpower.org

Fixed Speed/ Induction type Wind Turbine Generator

Variable Speed type Wind Turbine Generator

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

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?

appr.20,00,000 kWh

160 m

Increase in capacityIn a mere 20 years, the yieldOf wind turbines has increased 100-fold.With the new 6 MW Turbines,It will multiply another fivefold.

2010

6.000 kW

170 m

Increase in capacity and efficiency: Development of turbine technology

Criteria for Site Selection

2.5 D

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 .

CSP - TROUGH TECHNOLOGY

CSP - TOWER TECHNOLOGY

CSP - DISH TECHNOLOGY

Typical arrangement of an Small Hydro Power station

SHP station on a canal

SHP station on a river

WIND ENERGY HARNESSED

SR Maximum Wind -17.08.10 AT 18:59 HRS

a) % of Wind in SR I/C – 17% % of Wind Gen in SR Demand Met – 14.9 %

b) % of Wind in TN I/C – 39.4 % % of Wind Gen in TN Demand - 31.3 %

Capacities in MW as on 31-12-10 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

Source : MNRE

Wind Power Potential Wind Power Potential

Sl.No. Sources Potential in MW1 Andhra Pradesh 89682 Gujarat 106453 Karnataka 115314 Madhya Pradesh 10195 Maharashtra 45846 Rajasthan 48587 Tamil Nadu 55308 Kerala 11719 Orissa 255

48561Total

State Wise -Wind potential in India

Map showing Solar radiation across Map showing Solar radiation across India India

Potential Capacity of RE Sources StatewisePotential Capacity of RE Sources Statewise

State Wind SHP BiomassAndhra Pradesh 8968 552 830Arunchal Pradesh 1333 Chattisgarh 830Gujarat 10645 916Haryana 110 Himachal Pradesh 2268 Jammu & Kashmir 1411 Karnataka 11531 643 859Kerala 1171 Maharashtra 4584 762 1711Madhra Pradesh 1019 400 1059Nagaland 28.67 Punjab 390 Rajasthan 4858 63 1289Tamilnadu 5530 1186Uttaranchal 1609 West Bengal 450

Total 48756 9569.67 8680

Wind MapWind MapSolar MapSolar MapBoth Solar and wind Both Solar and wind concentration are concentration are geographically samegeographically same

KARNATAKA WIND GENERATION ON MAXIMUM GENERATION DAY 29.277 MU on Date - 31-07-2010

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Diurnal patterns

Seasonal patterns

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

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

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.

Planning Transmission system for RE

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.

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

50Hz

Load Generation

TN WIND GENERATION

TAMILNADU WIND GENERATION ON MAXIMUM GENERATION DAY 59.61 MU on 16-07-2010

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(28% of Energy)

SR Maximum Wind -17.08.10 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 – 39.4 % % of Wind Gen in TN Demand - 31.3 %

Intermittancy: not continuously availableVariability : variable in magnitudeUncertainity : Variations may not be as Expected

KARNATAKA WIND GENERATION

KARNATAKA WIND GENERATION ON MAXIMUM GENERATION DAY 29.277 MU on Date - 31-07-2010

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TN WIND GENERATION MUs

Data are as received from TN

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

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

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

SCATTERED PLOT OF UNCERTAINTY Vs ACTUAL GENERATION OF TNEB WIND GENERATION (HOUR WISE) (Aug-10 to Mar-11)

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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.

How the Forecast is done?

Flow Diagram of a Forecast model

NWPForecast

Suite of Models

Powermodel

Powerforecast

Modeladaptation

Modeladaptation

Wind speedforecast

HistoricSCADA

LiveSCADA

NWPForecast

NWPForecast

Adaptive statistics ClimatologyTime Series

Intelligent Model Combination

LiveSCADAOptimised combination of NWP

suppliersIncorporation of mesoscale models

Regular live feedback from the wind farm“Learning” Algorithms for:

MeteorologyPower models

Sitegeography

Comparison of Actual power with predicted Values

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.

Single Turbine

A Windfarm

A Control Area

Variability over a large Area is lesser

Forecast to be furnished to Host Control Area

For Operational planning and Real time Monitoring

RLDC For Operational planning and Real time Monitoring 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

Forecasting/Scheduling

Telemetry

Real TimeMonitoring

ReserveBalancing

Trading

Forecast Data Flow to various functionalities

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

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 01-01-12

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?

Intervals for Revisions of Intra-day Bilateral Trade Schedules

3 hours

6 blocks notice

3 hours 3 hours 3 hours 3 hours 3 hours 3 hours 3 hours

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).

Why limit Sale under Collective transactions (Px) ?

Px schedules can not be revised

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

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

SCADA and telemetry :

WIND MILLS TELEMETRY TYPICAL LAYOUT

110 kV Bus

33kV or 11 kV Bus

LOADS

Untelemetered

X MW injectedto 110kV Bus

(Telemetered)

WIND MILLS

Typical Windfarm LayoutTypical Windfarm Layout

VCBVCB

VCBVCB

VCBVCB

33KV - Internal Lines



33KV - External Lines



Cluster-1

Cluster-2

Cluster-3

L1

L2

L3

Billing Meters

Transmission Grid

Grid Substation

WINDFARMWINDFARM WINDFARM SSWINDFARM SS

G1 G2

UTILITY SSUTILITY SS

220 KV132 KV110 KV66 KV

Local Loads

Congestion anticipated after Kudankulam (2x1000MW) new IPPs in coastal TN and AP come up

EVACUATION STUDY FOR TN WIND: NETWORK SUFFICIENCY

PRESENTLY THERE ARE NO NETWORK CONSTRAINTS FOR EVACUATION WIND UPTO 2500 MW.

NEW ELEMENTS ADDED FOR STRENGTHENING ARE HIGHLIGHTED

Each Region has to conductStudies to know How much wind can be accomodated

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

Reactive Compensation (0.95 pf lag or lead) Fault Ride Through (FRT) Lightning protection of WTG system shall be

according to IEC TR 61400-24 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 .

Protection requirements for RE :

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.

Commercial Options for RE GenOption Schedul

ing 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

By SLDC

Yes Mutually negotiated As per state policy Required

3 Bilateral with an Intra-Regional state buyer

By RLDC

Yes Mutually negotiated Max once in 3 hrs. 1.5hrs notice

Required

4 Bilateral with an Inter-Regional state buyer

By RLDCs

Yes Mutually negotiated Max once in3 hrs. 1.5hrs notice

Required

5 Collective transaction through Px

By RLDCs

No Price discovered thro’ Auction

Not allowed Required

Options for DISCOMs to fulfill RPO

RPO

Buy Power @ Preferential Tariff

Buy REC

What is RPO ? Renewable Purchase Obligation specified by SERC. It will :Incentivise the RE generator Socialise the cost of variations by REReduce the Geographical imbalances in RE spread

Options for RE generators

Sale of Electricity at Market Price in open market

Sale of electricity to Obligated Entities at State regulated tariff

Prefrential Tariff[State Regulated Tariff]

REC [Solar & Non-Solar]

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

Sell to DisComs at Price ≤ Pooled Cost of Power Purchase*

REC OptionElectricity Green

Attributes

REC Framework: Eligibility

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 Preferential

Tariff

PPA at Average Power

Purchase Cost

Eligible Eligible Not Eligible

Eligible if All Three conditions mentioned above

are met 04/18/23

Grid Connected RE technology approved by MNRE

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

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 (Rs/ MWh)

Forbearance Price 3,900 17,000

Floor Price 1,500 12,000

REC sale as on 30-03-11Non-Solar Solar

RECs issued 532 Nil

Buy Bid 70377 30001

Sell Bid 150+274 Nil

Cleared Volume 150+274 Nil

Price discovered 3900/2225 -----

No. of participants 15

World wide Wind Installed capacities

As in 2010

Country Inst. capacity (MW)

China 42,287

United States 40,180

Germany 27,214

Spain 20,676

India 13,065

Italy 5,660

France 5,660

United Kingdom 5,204

Canada 4,009

Denmark 3,752

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.

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

KADAMPARAI

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6MUs pumped

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

Integration of Renewable Energy P.R.Raghuram GM, SRLDC [email protected].

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Transcript of Integration of Renewable Energy P.R.Raghuram GM, SRLDC [email protected].