Renewable Energy Sources (RES) Grid Integration: Key Issues
and Challenges
Bharat Singh
Indian Institute of Technology Mandi
Outline
Grid connection issues
Economic issues
System Operational Aspects
Reasons for Renewable Energy in India
why and why now??
Declining Fossil Fuel Supplies
Environmental* Concerns (Kyoto Protocol,1997)
Increasing Cost of Fossil Fuels
Business Opportunities
Energy Security
Energy independence
1 MW of wind plant in one year can displace 1500 tons of CO2, 6.5 tons
of SO2 and 3.2 tons of NOx. (REPP report, Washington July 2003)
Introduction
Huge power shortages in the range of 3% to 21% in
States with national average energy shortage of about
10.3% and peak demand shortage of 15.4%.
Renewable energy technologies have a good potential
in India.
Substantial efforts have been made to harness the
non-conventional and renewable sources of energy
during the last three decades.
The vision of Indian renewable energy program is
“to develop new and renewable energy technologies, processes,
materials, components, sub-systems, products and services at par with
international specifications, standards and performance parameters in
order to make the country a net foreign exchange earner in the sector
and deploy such indigenously developed and/or manufactured products
and services in furtherance of the national goal of energy security”.
Introduction
In 1981, the Government of India (GOI) established
a Commission for Additional Sources of Energy
(CASE) under the Department of Science and
Technology (DST).
In 1982, the commission was given full status of a
department called as Department of Non-conventional
Energy Sources (DNES) and put at par with other
energy departments, such as coal and power.
Finally, in 1992, the GOI upgraded the department
to a full-fledged ministry known as Ministry of Nonconventional Energy Sources (MNES) exclusively
devoted to the renewable energy promotion.
MNES is renamed as Ministry of New and
5
Renewable Energy (MNRE) in 2006.
Introduction
The MNRE efforts have been identified in following four areas:
Power generation from renewable
Grid-interactive renewable power (Wind Power, Small Hydro
Power (SHP), Biomass Power, Urban & Industrial Waste-toenergy and Solar Power),
Captive/CHP/Distributed Renewable Power (such as
Biomass/Cogeneration, Biomass Gasifier, Waste-to- energy,
Aero-generator/Hybrid Systems)
Rural & Decentralized Energy System (such as Familytype Biogas Plants, Home Lighting System, Solar Photovoltaic
(SPV)/Thermal Program, Wind Pumps)
Remote Village Electrification
Other programs (such as Energy Parks, Akshay Urja Shops
and Hybrid Vehicles, Geothermal and Tidal)
6
Renewable Energy Development in India
Government of India has created conducive environment
for speedy development of RES and to attract private
investors by providing
 Subsidy and fiscal incentives,
 policies support,
 regulatory & legislative framework,
 finances, consultancy services,
 research design & development,
 up-gradation of existing technologies, and,
 planning & resource assessment.
Government is a catalyst and facilitator, however, the
implementation is being carried out by the States or by the
private sector.
Several States have so far announced promotional policies
7
for RES.
All India Installed Capacity (on 30.06.09)
S.
No.
Fuel
Share
Percentage
(in MW) (%)
1
Total
Thermal
Coal
Gas
Oil
96044
78459
16385
1200
63
2
Hydro
36917
25
3
Renewable*
13878
9
4
Nuclear
4120
3
Total
150810
3%
63%
100
25%
9%
HYDRO
THERMAL
RENEWABLES
NUCLEAR
8
* 348 MW Captive/CHP/Distributed
Renewable power
Indian Power System - Present
All figs. in MW
I.C-36500
PD- 31500
Deficit- 5000
I.C-2570
PD- 1470
Deficit- 300
Trans. Grid Comprises:
•765/400kV Lines: 77500 ckt-km
•220/132kV Lines:114600 ckt-km
•HVDC bi-poles : 3 nos.
•HVDC back-to-back : 7 nos.
I.C-18750
PD- 10400
Surplus- 5000
(incl Talcher)
I.C-37500
PD- 36500
Deficit- 9000
I.C-34580
PD- 26000
Deficit-3800
•FSC – 18 nos.; TCSC – 6
nos.
NER, ER, NR & WR operating
as single grid of 90,000MW
Inter-regional capacity:
14600 MW
Est. Potential and Achievement of RES (as on 31.03.11)
S. No.
Sources/Systems
I. Power Generation from Renewable
Grid-interactive Renewable Power
1
Wind Power
2
Biomass Power (Agro residues)
3
4
5
6
1
2
3
4
5
1
2
3
4
5
6
1
2
3
4
5
Small Hydro Power (up to 25 MW)
Cogeneration Bagasse
Waste-to-energy
Solar Power
Captive/CHP/Distributed Renewable Power
Biomass Power/ Cogeneration(non-bagasse)
Biomass Gasifier
Waste-to-energy
Solar PV Power Plants & Street lights
Aero-generators/Hybrid Systems
Total
II. Electrification
III. Rural Decentralized Energy Systems
Family-type Biogas Plant
Est. Potential
Achievements
45195 MW
16881 MW
14756 MW
1000 MW
15000 MW
5000 MW
2700 MW
3042 MW
1667 MW
70 MW
37 MW
153 MW
160 MW
31 MW
3 MW
1 MW
19774 MW
4254 villages + 1156 hamlets
Numbers
4090000
Home Lighting System
Solar Lantern
SPV Pumps
Solar Cookers
Wind Pumps
IV. Other programs
Energy Parks
Akshay Urja Shops
Hybrid Vehicles
Geothermal Energy
Tidal Energy
434692
10000 MW
10000 MW
697419
7148
63700
1347
Numbers
504
289
270
---
Specialized Centers/Institutes
Centre of Wind Energy Technology (CWET), Chennai,
established in 1982, to serves as the technical focal point for
wind power development.
Solar Energy Centre (SEC), Gurgaon, established in 1982, is a
dedicated unit of the MNRE for development of solar energy
technologies and serves as an effective interface between the
Government and user organizations.
Alternate Hydro Energy Centre (AHEC), Roorkee, was
established in 1982, to promote SHP projects & other renewable
energy sources e.g. biomass, solar, wind, etc.
Sardar Swaran Singh - National Institute of Renewable Energy,
Kaputhala, is being established for development of bio-energy,
including bio-fuels, and synthetic fuels.
Indian Renewable Energy Development Agency Limited (IREDA),
New Delhi, established in 1987, promotes and finances renewable
11
energy and energy efficiency/ conservation.
Jawaharlal Nehru National Solar
Mission
To create an enabling policy framework for the deployment of 20,000 MW of solar
power by 2022.
To ramp up capacity of grid-connected solar power generation to 1000 MW within
three years – by 2013;
an additional 3000 MW by 2017 through the mandatory use of the renewable purchase
obligation by utilities backed with a preferential tariff.
This capacity can be more than doubled – reaching 10,000MW installed power by 2017
or more, based on the enhanced and enabled international finance and technology
transfer.
The ambitious target for 2022 of 20,000 MW or more, will be dependent on the
‘learning’ of the first two phases, which if successful, could lead to conditions of gridcompetitive solar power.
Jawaharlal Nehru National Solar
Mission
To create favourable conditions for solar manufacturing capability, particularly solar
thermal for indigenous production and market leadership.
To promote programs for off grid applications, reaching 1000 MW by 2017 and 2000
MW by 2022.
To achieve 15 million square meters solar thermal collector area by 2017 and 20 million
square meters solar thermal collector area by 2022.
To deploy 20 million solar lighting systems for rural areas by 2022.
 CERC has announced preferential tariff of Rs. 18.44 per unit for solar PV power and
Rs. 13.45 per unit for solar thermal power for 25 years;
Tariff Policy
The Electricity Act 2003 has paved the way for setting up of
State Electricity Regulatory Commissions (SERCs) for providing
conducive atmosphere for the rapid development of power
generation including renewable energy.
The National Tariff Policy that was notified by the
Ministry of Power in January 2006, in continuation with
the Electricity Act 2003.
The National Electricity Policy 2005 stipulates the progressive
of electricity generation from non-conventional sources. Setting
renewable energy targets and preferential feed-in tariffs for
renewable energy procurement by the respective SERC.
Several SERCs in turn, provided concessional feed-in tariffs
(mostly decided by cost-based approach), wheeling, banking of
14
energy for future use, third party sale and power evacuation
facilities.
Preferential Tariffs/Policy Announced by the
SERC’s for Wind/Biomass/SHP
Sources
Items
Wind
Wheeling
Charges
States
Banking
Buy-back (INR/kWh)
Wheeling
Charges
Biomass/Cogeneration
Banking
SHP
Buy-back
(INR/kWh)
2.63
2.69
Andhra
Pradesh
2% of energy
12 Months
3.37
28.4 % +
INR 0.5 kWh
Chhattisgarh
Gujrat
Haryana
HP
Karnataka
-4% of energy
2% of energy
-2% of energy
--Allowed
-2% /Month
for 12
Month
-3.37 fixed for 20 yrs.
4.08 + Escalation 1.5%
-3.40 fixed for 10 years
6 % of energy
4 % of energy
2 % of energy
-5% surcharge
Not Allowed
Allowed
Allowed
-Allowed at 2%
INR 1.13/kWh
2.67
3.0
4.0
-2.27
--2.25
2.50
2.90
Kerala
5% of energy
9 Months
(Jun.–Feb.)
3.14 fixed for 20 years
5% of energy
Allowed 4 Months
2.80
--
Maharastra
2% of energy
+5%trans.loss
12 Months
3.50 + Escalation of 0.15 for 13
years from documentation of the
project
7% of energy
Allowed
3.05
2.25
Madhya
Pradesh
2% of energy
Not allowed
3.97 (with decrease of 0.7 upto
4th yr ) then fixed at 3.30 from 5th
yr onwards uniformly for 20
years
--
Allowed
3.33
2.25
Punjab
--
--
--
2% of energy
Allowed12
Months
3.59
2.73
Rajasthan
10% of energy
3 Months
3.59 for Jaisalmer, Jodhpur etc.
and 3.67 for other districts
10% of energy
Allowed 12
Months
3.60
2.75
Tamil Nadu
5% of energy
5%
12 months
2.90 (Levelised)
2-10%
Allowed at 2%
charge
2.73
--
--
--
--
12.5% of energy
Allowed
24 Months
2.67
2.25
INR 0.3/kWh
6 Months
To be decided on case to case
with a cap of 4
--
--
--
--
Uttar Pradesh
West-Bengal
Allowed at 2%
for 8-12
Buy-back
(INR/kWh)
Open access transaction is allowed in all States. Third party sale is allowed in case of wind in all States. RPS is announced in each State
Incentives/Promotion Policies
The MNRE has been providing capital subsidy as Central
Financial Assistance (CFA), depending on type and the size of the
plants, and category of institutions and areas to promote RES.
S.
No.
Sources/Systems
Central Financial Assistance (in INR)
1
2
Wind Power
Biomass Power (Agro- residues)
Special Category States
Other States
(NE region, , J&K, HP and Uttaranchal)
3 × MF
2.5 × MF
0.25 × MF
0.20 × MF
3(i)
3(ii)
Small Hydro Power (up to 25 MW)
Renovation and Modernization of
SHP
Biomass Power using Advanced
Technologies
Cogeneration Bagasse (Private)
40 bar & above
Cogeneration Bagasse (Public/joint)
40 bar & above
60 bar & above
80 bar & above
4
5
6
7
Waste-to-energy
2.2 × MF
1.125 × MF
1.5 × MF
0.75 × MF
1.2 × MF
1.0 × MF
0.18 × MF
15 × MF
0.40 × MF
0.50 × MF
0.60 × MF
0.40 × MF
0.50× MF
0.60 × MF
20% higher than other States
MF = 107 × C0.646, C = Capacity of the project in MW
(0.50-1.0)×107
Incentives/Promotion Policies
Besides the CFA, fiscal incentives such as 80% accelerated
depreciation, concessional import duty, excise duty, tax
holiday for several years, etc., are available for RES.
Item
Accelerated
Depreciation
Description
80% depreciation in the first year can be claimed for the following
equipment:
for Wind: Extra 20% after March 2005 for new plant &
machinery
for Cogeneration Systems:
1.Back pressure, pass-out, controlled extraction, extraction–cumcondensing turbine for co-generation with pressure boilers
2.Vapour absorption refrigeration systems
3.Organic Rankine cycle power systems
4.Low inlet pressures small steam turbines
Tax
Ten years tax holidays.
Customs Duty Concessional customs and excise duty exemption for machinery
and components for initial setting up of projects.
Sales Tax
Exemption is available in certain States
Grid Connection Issues
Technical guidelines and requirements for RES are varying with
one State to other States and not good enough for the large
RES integration into the grid.
In order to promote RES and to maintain common grid discipline
there is an urgent need of a specific and common grid code for
RES in India
Grid Connection Issues
Grid connection requirements: Intermittency
•
•
•
•
Active power/ Frequency Regulation
Reactive power/Voltage Control
Fault-ride through capability
Scheduling/Dispatch/Forecasting
Grid connectivity or evacuation of energy:
•
•
Remote areas, augmentation of existing power transmission lines or new lines
Interconnection point
Wind Power
What is Wind Power
Wind turbines extract the
kinetic energy from the wind and
converts into generator torque.
Generator converts this torque
into electricity and feeds into the
grid
Power in the Wind
Kinetic Energy = Work = ½mV2
where: m= mass of moving object
V = velocity of wind
What is the mass of moving air?
= density (ρ) x volume (Area x distance)
= ρ x A x d
Power
= Kinetic Energy / t
= ½ρAV3
A
V
d
Wind Power Status (Jan. 2011)
The total installed wind power capacity is 195 GW
China
USA
Germany
Spain
India
(45 GW)
(40 GW)
(27 GW)
(20 GW)
(14 GW)
Estimated Wind Power Potential in India
State
Gross Potential (MW)
Andhra Pradesh
9063
Gujarat
7362
Karnataka
7161
Kerala
1026
Madhya Pradesh
4978
Maharashtra
4519
Orissa
1520
Rajasthan
6672
Tamil Nadu
4159
West Bengal
32
TOTAL
46092
The wind power potential on macro level based data collected from 10 states
considering only 1% of land availability is around 46092 MW.
Government Support for RES
With different policies such as tax holiday etc
Regulatory & legislative framework
Subsidy and fiscal incentives
Finances and consultancy services
Research design & development
Planning & resource assessment
Indian Scenario for Wind power
Wind potential 46 GW, WT manufacturers claim double
Concentration in few regions only
Installed capacity has exceeded 10% in many states and increasing with high
rate
Specific nationally harmonised GCR for wind power are in urgent need
Existing Situation
Each State has different requirements for grid integration
Mostly power factor is specified & maintained at PCC
PCC is highly disputed among states and wind farm developers
No active grid support requirement is specified
Indian Perspective plan 2022
REPORT OF THE WORKING GROUP on, “NEW AND RENEWABLE ENERGY” for XIth
FIVE YEAR PLAN (2007-12)
Global Growth of Wind Power
Annual Installed Capacity
Cumulative Installed Capacity
INTRODUCTION
 Conventional power plants
 Large synchronous machines
 Provides primary & secondary control
 Meet the specific grid connection requirements (GCR)
 With increased penetration of wind power
 Mostly converter interfaced small asynchronous generators,
 Poses new challenges in maintaining reliability and stability of electricity supply,
 Advanced GCR are required to be developed for efficient, stable and secure
operation of grid ,
 Loss of generation cannot be tolerable, wind turbines should remain connected
and actively support the grid,
 Need to perform suitable studies to analyze the interaction of wind power with
existing grid,
 Need to develop several solutions to improve and mitigate negative
consequences on the existing grid, if any.
WIND ENERGY CONVERSION SCHEME
GENERATOR SYSTEMS FOR WIND TURBINES
Fixed speed
 A reactive power compensator is needed to control the
voltage
 Poor power quality
 Gearbox torque is of concern
 Robust and maintainece free
 Reduced cost
GENERATOR SYSTEMS FOR WIND TURBINES
Variable speed converter interfaced generators
Contorlabiltiy over active and reactive
power
 High energy efficiecny
 Improved Power Quality
 More expensive
More complex system with more
sensitive electronic parts
DFIG is most popular scheme
Reduced Power Converter Rating
Reduced Losses
Reduced EMI filters
Reduced cost
GENERATOR SYSTEMS FOR WIND TURBINES
Wind turbine power
Power from a wind turbine rotor = Cp½ρAV3
• Cp is called the power coefficient
• Cp is the percentage of power in the wind that is converted into
mechanical energy
• Cp, max = 0.5926 (Betz limit)
Power coefficient varies with tip speed ratio
λ=
rω
vw
Maximum power extraction can be realized
with a speed variable system
By measuring the wind velocity and adjust the
turbine rotating speed to keep the power
coefficient Cp at its maximum value
Grid Code Requirement’s Issued by TSO’s
Country
TSO
Author
Title
Issue Year
Denmark
Eltra/Elkraft
Eltra/Elkraft
Regulation TF 3.2.5, Wind turbines connected to grids with voltages above 100 kV
2004
Denmark
Eltra/Elkraft
Eltra/Elkraft
Regulation TF 3.2.5, Wind turbines connected to grids with voltages below 100 kV
2004
Germany
E.ON.
E.ON.
Grid Code High and Extra High Voltage
2006
U.K.
NGET
NGET
Grid Code
2008
Sweden
Svenska Kraftnät
(SvK)
Svenska Kraftnät
(SvK)
Affärsverket svenska kraftnäts föreskrifter och allmänna radom driftsäkerhetsteknisk
utformning avproduktionsanläggningar
2005
Ireland
EirGrid
EirGrid
EirGrid Grid Code: WFPS1- Wind Farm Power Station Grid Code Provisions (Ver. 3)
2007
Scotland
Scottish
Electric
Guidance note for the connection of wind farm
2002
China
ALL
CEPRI
Technical Rules for Connecting Wind Farm to Power System
2005
FERC
FERC Order No. 661-A, Interconnection for Wind Energy
2005
PSE
INSTRUKCJA RUCHU I EKSPLOATACJI SIECI PRZESYŁOWEJ
2006
U.S.A.
Poland
PSE
Hydro
Scottish
Electric
Hydro
GCR CONNECTION REQUIREMENTS
Active Power Control
Frequency Control
Voltage Control
Wind Farm Protection (Fault-ride through)
34
INDIAN ELECTRICITY GRID CODE FOR WIND
FARMS (IEGCWF)
 IEGCWF must be read in conjunction with
 Indian electricity grid code (IEGC),
 Technical standards for connectivity to the grid, regulations 2007, and
 State electricity grid codes issued by respective states of India.
 It must also be emphasized, that all capabilities will not be
exploited in all wind turbines at all times. Connection codes
shall provide the capabilities and characteristics of system
components are available when ever needed for safe and
reliable system operation.
 All requirements are to be met at the connection point.
Connection point can be defined as a point in the
transmission network, to which the wind turbine or wind
farm is to be connected.
INDIAN ELECTRICITY GRID CODE FOR WIND
FARMS (IEGCWF)
 It is assumed that wind power is fed into the grid when and
where available on priority basis
 It is assumed that wind power is remunerated for active
power by fixed price in respective States and for reactive
power according to Section 6.6 of IEGC
 The Beneficiary pays for VAr drawl when voltage at the metering
point is below 97%
 The Beneficiary gets paid for VAr return when voltage is below 97%
 The Beneficiary gets paid for VAr drawl when voltage is above 103%
 The Beneficiary pays for VAr return when voltage is above 103%
ACTIVE POWER CONTROL
Active Power Control is a requirement for generating units to be able to
deliver power and remain connected to the network even if the system
frequency deviates from specified one
An adjustable upper limit to the active power production from the wind
farm shall be available whenever the wind farm is in operation
 The upper limit shall control that the active power production, measured as a 15
minute average value, does not exceed a specified level and the limit shall be
adjustable by remote signals.
 It must be possible to set the limit to any value with an accuracy of ±5%, in the range
from 20% to 100% of the wind farm rated power.
Ramping control of active power production must be possible.
 Limit on ramping speed of active power production from the wind turbine in upwards
direction to 10 % of rated power per minute.
 No requirement for down ramping due to fast wind speed decays, but to limit the
down ramping speed to 10 % of rated power per minute, when the maximum power
output limit is reduced by a control action.
ACTIVE POWER CONTROL
Fast down regulation. It must be possible to regulate the active power
from the wind turbine down from 100% to 20% of rated power in less
than 5 seconds.
 This functionality is required for system protection schemes.
 Some system protection schemes implemented for stability purposes require
the active power to be restored within short time after down regulation.
 For that reason disconnection of a number of wind turbines within a wind
farm cannot be used to fulfill this requirement.
 Frequency control. Automatic control of the wind turbine active
production as a function of the system frequency must be possible.
 The control function must be proportional to frequency deviations and must
be provided with a dead-band as shown earlier.
 The detailed settings will be provided by the respective State utilities.
REACTIVE POWER (OR VOLTAGE)CONTROL
 Voltage control is a requirement for generating units to supply
lagging/leading reactive power at the grid connection point.
 Wind turbine should be capable of supplying a proportion of the
systems reactive capacity, including the dynamic capability and
should contribute to maintain the reactive power balance.
 Requirements of the grid codes for reactive power capability
demand that the power factor be maintained in the specified
range.
 The wind farm must have adequate reactive capacity to be able to
be operated with zero reactive exchange with the network
measured at the connection point, when the voltage and the
frequency are within normal operation limits.
REACTIVE POWER (OR VOLTAGE)CONTROL
Wind farms are required to balance voltage deviations at the
connection point by adjusting their reactive power exchange and
moreover by setting up predetermined power factors.
 Wind Farms shall be capable of operating at rated output for power factor
varying between 0.9 lagging (over-excited) to 0.95 leading (under-excited).
 The above performance shall also be achieved with voltage variation of ±
5% of nominal, frequency variation of ± 3% and combined voltage and
frequency variation of ±5%, as given for conventional generators.
The reactive output of the wind farm must be controllable in one of the
two following control modes according to SU specifications:
 The control shall operate automatically and on a continuous basis. The wind
farm shall be able to maintain acceptable small exchange of reactive
power at all active power production levels.
 The wind farm must be able to automatically control its reactive power
output as a function of the voltage in the connection point with the purpose
of controlling the voltage.
REACTIVE POWER (OR
VOLTAGE)CONTROL
 According to the German grid code, the wind turbines must provide, being a
mandatory requirement, voltage support during voltage dips.
 Wind turbines have to supply at least 1.0 p.u. reactive current when the voltage falls
below 50%.
 A dead band of 10% is introduced to avoid undesirable control actions. However, for
the wind farms connected to the high voltage grid, the continuous voltage control
without dead band is also under consideration.
Voltage
requirements
control
REACTIVE POWER (OR VOLTAGE)CONTROL
 Older WPG based on IG require a reactive power support from the
power systems.
 Modern WPG can provide dynamic reactive power capability directly
from the power electronics converters
 Several TSO required that a wind farm owner supplies a PQ diagram
showing the regulation capability for reactive power of the installation
at the connection point.
Capability curve of DFIG
FAULT-RIDE THROUGH
 FRT: is the requirement for generating units to revert to
normal operation when fault on power system is cleared.
 FRT requirement is imposed on a wind power generator so
that it remains stable and connected to the network during
the network faults.
 Disconnection from grid may worsen a critical grid situation
and can threaten the security standards when wind
penetration is high.
FAULT-RIDE THROUGH IN GERMANY
 In Germany, the wind generating plants are
expected to acquit themselves during a lowvoltage disturbance as summarized in a voltage
vs. time curve.
 Wind turbines are required to stay on the grid
within areas 1 and 2. If a wind turbine faces
overloads, stability or other kinds of technical
problems in area 2, it can be disconnected itself
from the grid provided a resynchronization can
take place after 2s.
 Moreover, it must be able to increase the active
power output following the resynchronization by
gradients of at least 10% of the nominal power
per second.
Definition
requirements
of
FRT
FAULT-RIDE THROUGH
The wind farm must be able to continue operation during
and after disturbances in the transmission network. This
requirement applies under the following conditions:
 The wind farm and the wind turbines in the wind farm must be able to stay
connected to the system and to maintain operation during and after
dimensioning faults in the transmission system.
 The wind farm may disconnect from the system, if the voltage in the
connection point during or after a system disturbance do fall below the
certain levels.
The fault duration, where the voltage in the connection
point may be zero, is 100 milliseconds for 800 kV & 400 kV
and 160 milliseconds for 220 kV & 132 kV.
Inferences
 GCR are set up to specify the relevant requirements for
efficient and secure operation of power system for all
network users and these specifications have to be met in
order to integrate wind turbines into the grid.
 The GCR for Indian scenario has been laid down in order
to provide for adequate safe operation and reliability of
the interconnected Indian power system.
DOUBLY-FED INDUCTION GENERATOR
RSC
Chopper
LSC
Crowbar
DFIG
UT
Fault-ride through (FRT) : Objectives & Solutions
Protection of converters
Grid codes fulfillment
Reducing mechanical stress
Crowbar
Chopper
Series connection
Extra series converter
UNIFIED ARCHITECTURE (UA) OF DFIG
An extra series grid side converter (SGSC) sharing common
DC bus with conventional DFIG system
Reactive Power Capability of WT
According to advanced GCR wind farms should have
 To supply/consume active/ reactive power to/from the grid
 To supplies a P-Q diagram showing the regulation capability for reactive power
 These requirements are defined with respect to the power factor as a function of the
voltage at the PCC with the main grid
Selection of partial rated converters rating is crucial in terms of cost,
efficiency, operating speed range and reactive power capability
 A complete capability curve for DFIG system is developed considering
optimum RSC converter rating and GSC capability.
DFIG WITH BACK-TO-BACK PWM VOLTAGE
SOURCE CONVERTERS
GB
DFIG
3
GRID
3
3
ROTOR SIDE
CONVERTER
CONTROL
GRID SIDE
CONVERTER
CONTROL
End heating limit
Capability curve of SG
REACTIVE POWER CAPABILITY OF DFIG
First, 3 steady state models of DFIG are derived in terms
 stator and rotor voltage (VS,VR),
 stator voltage and rotor current (VS,IR), and
 stator voltage and stator current (VS,IS),
to derive the limitations in the reactive power production /consumption,
caused by the rotor voltage, rotor current and stator current limits,
respectively
Secondly, reactive power capability of the Grid Side
Converter (GSC) is included.
Finally, a complete capability curve of conventional &
modified DFIG for stator voltages is developed by
optimization of rotor speed employing maximum power point
tracking (MPPT) algorithm.
REACTIVE POWER CAPABILITY OF DFIG
GB
3
DFIG
GRID
3
3
ROTOR SIDE
CONVERTER
CONTROL
GRID SIDE
CONVERTER
CONTROL
 The fundamental steady state equations for the DFIG are given by:
Voltage equations: V s = jωS ψ S
Flux equations:
&
V r = RR I R + j (ωS −ωR )ψ R
ψ R = LR I R + LM I S
ψ S = LS I S + LM I R &
(
Eliminating flux linkages, we have V S = jω S LS I S + LM I R
)
V R = RR I R + jsω S ( LR I R + LM I S )
&
ROTOR VOLTAGE LIMITATION
2
�
�
L �
s ￗRR
LM
PS = 3VS2 � M �
−
3
V
V
�
S
R
2
�LS �RR2 + ( sωS LSC )
�LS
�
L
�
−3VS Vr m
Ls
�
�
�
�
�
�
�
�
� cos ( δ +δK )
�
�R 2 r +( swLSC ) 2
�
6
4
2
S
Stator Reactive Power
(p.u.)
Q
QS
2
3VS2 � ( sωS LM ) LSC
�
=
1+
ωS LS � RR2 +( sωS LSC ) 2
�
�
�
� sin ( δ + δ K )
�
�
� RR2 + ( sωS LSC ) 2
�
�
0
-2
s=0.3
-4
s=0.2
s=-0.2
s=0.1
s=-0.1
-6
-8
-10
-12
0
2
4
6
8
T ot al Act ive P ower P E (p.u.)
10
�
�
�
�
�
ROTOR CURRENT LIMITATION
PS = −3
LM
VS I R cosθ
LS
S
Stator Reactive Power
(p.u.)Q
VS2
L
QS =3
+3 M VS I R sin θ
LM .ωS
LS
s= -0.2 t o 0.3
0.5
0
-0.5
-1
0
0.2
0.4
0.6
0.8
T ot al Act ive P ower P E (p.u.)
1
1.2
STATOR CURRENT LIMITATION
PS =−3VS I R cos φ
QS =3VS I R sin φ
S
Stator Reactive Power
(p.u.)
Q
1
s = -0.2 t o 0.3
0.5
0
-0.5
-1
0
0.2
0.4
0.6
0.8
T ot al Act ive P ower P E (p.u.)
1
1.2
CAPABILITY CURVE OF DFIG
 The locus of capability curve is obtained by the minimum absolute value of
three limiting curves governed by stator current, rotor current and rotor
voltage during entire operation of optimized slip
Stator Reactive Power Q S (p.u.), Slip
0.6
0.4
Rotor curent limit
0.2
Mechanical power limit
0
slip
-0.2
-0.4
Rotor voltage limit
Stator curent limit
-0.6
-0.8
-1
0
0.2
0.4
0.6
T otal Active power P E (p.u.)
0.8
1
SELECTION OF OPTIMAL RSC RATING
1.5
Vr=0.46
50
(p.u.)
1
40
Stator Reactive Power Q
S
Percentage (%)
Vr=0.42
0.5
Vr=0.38
Ir=1.0
Vr=0.34
0
20
10
0
Vr=0.30
-0.5
30
0
0.2
0.4
0.6
Total Active Power P E (p.u.)
0.8
Rotor voltage limitation curves for
Variation in RSC rating
0.9
0.95
1
1.05
Grid Voltage (p.u.)
1.1
1
Percentage increase in RSC rating w. r. t.
|±smax| × Ps required for variation in grid voltage
to exclude rotor voltage limits from capability curve
CAPABILITY CURVE WITH OPTIMAL RSC RATING
Stator Reactive Power Q s(p.u.), Slip
0.6
Rotor cuurent limit
0.4
0.2
0
Slip
-0.2
-0.4
-0.6
-0.8
-1
Stator cuurent limit
0
0.2
0.4
0.6
T otal Active Power P E (p.u.)
0.8
For RSC rating = 0.3789 p.u. i.e. (1.263 × |s max|)
1
COMPLETE CAPABILITY CURVE OF DFIG
QGSC = ± (VGSC .I GSC ) 2 − PR2
GSC reactive power capability
1
1
Stator Power
(p.u.)
0.5
E
0
Total Reactive Power Q
Q E (p.u.) , P S (p.u.) , P R (p.u.)
0.5
Rotor Power
-0.5
Slip
-1
-1.5
0
0.2
0.4
0.6
0.8
T otal Active Power P E (p.u.)
For RSC rating = 0.3 p.u.
1
0
-0.5
Slip
-1
-1.5
0
0.2
0.4
0.6
0.8
T otal Active Power P E (p.u.)
For RSC rating = 0.3789 p.u.
1
CAPABILITY CURVE OF UNIFIED ARCHITECTURE
1
E
Total Reactive Power
(p.u.)
Q
1.5
0.5
0
-0.5
-1
-1.5
0
0.2
0.4
0.6
T ot al Act ive P ower P E (p.u.)
0.8
1
Inference from RPC curve
It is established that the total reactive power generation is limited
by rotor voltage at low speeds and by rotor current at higher
speed.
However, the total reactive power consumption is limited by stator
current, for entire operating region.
Rotor voltage limitation can be avoided by increase of rotor side
converter rating.
During operating region of optimized slip, rotor power remains
considerably small and hence RPC of GSC can be effectively
utilized.
NONLINEAR ADAPTIVE NEURO-FUZZY CONTROLLERS FOR WT
 In the recent years, the controllability of wind turbines has been
improved by the introduction of power-electronic technologies.
 DFIG schemes have utilized PI controllers for power electronic
converters.
 However, the main problem with the PI controllers is that these will
work effectively under the conditions in which these have been
designed. If there is any deviation in the system conditions, such as
variation in load, variation in system parameters etc., the
conventional PI controllers may not give the satisfactory results.
 Computational intelligence (CI) techniques, such as fuzzy logic (FL),
neural network (NN), genetic algorithm (GA), etc., are showing
promising results in the several engineering applications.
 CI based controllers can lead to improved performance, enhanced
tuning and adaptive capabilities.
Mostly the FL and ANN are used, where an existing PI or PID
controller is simply replaced by a CI based controller
FL lack of a formal design methodology, the difficulty in
predicting stability and robustness of FL controlled systems
difficult to define the crisp rules for control difficult to define
and tune fuzzy rules and the fuzzy system parameters due to
large numbers of fuzzy rules
ANN require least computational time after training to select
optimal structure, parameter values and to minimize training set
are some of the issues to be addressed in the neural network
applications.
An ANFIS based hybrid intelligent controller is proposed for fast,
accurate, and efficient control of power electronic systems used
for wind turbines
63
ROTOR SIDE CONVERTER
CONTROL
Aims to control the stator active and reactive powers
ANFIS
ANFIS
ADAPTIVE NEURO-FUZZY INFERENCE SYSTEM
 In
an ANFIS technique, using a given input/output data set,
a fuzzy inference system (FIS) is constructed from an
extremely limited mathematical representation of the
system, whose membership function parameters are tuned
(adjusted) using either a back-propagation algorithm alone,
or in combination with a least squares type of method.
This allows fuzzy systems to learn from the data they are
modeling.
Hence ANFIS architecture can identify the near-optimal
MFs of FLC for achieving desired input-output mappings
BASIC STRUCTURE OF THE ANFIS
The adjustment of modifiable parameters is a two step process.
First, information is propagated forward in the network until Layer-4,
where the parameters are identified by a least-squares estimator.
Then the parameters in Layer-2 are modified using gradient descent.
BASIC STRUCTURE OF THE ANFIS
Layer 1
1
Every node i, in this layer, is a square node with a node function Oi = µ A ( x) where, x is the
input to node i, and Ai is the linguistic label (small, large, etc.,) associated with this node
function. Parameters in this layer are referred to as premise parameters.
i
Layer 2
Every node in this layer is a circle node, labeled Π, which multiplies the incoming signals
and sends the product out.
Layer 3
Every node in this layer is a circle node, labeled N. The I node calculates the ratio of the
I rule’s firing strength to the sum of all rule’s firing strengths, as given below. Outputs of
this layer are known as normalized firing strengths.
Layer 4
4
Every node i in this layer is a square node with a node function Oi = wi fi = wi ( pi x + qi y + ri )
where, wi is the output of layer 3, and { pi , qi , ri } is the parameter set. Parameters in
this layer will be referred to as consequent parameters.
Layer 5
The single node in this layer is a circle node labeled Σ that computes overall output as
the summation of all incoming signals.
DESIGN OF ANFIS CONTROLLERS
Output
Reference
Output
Reference
ANFIS
PI
Error
Actual Signal
Error
Actual Signal
Training and testing the ANFIS are generated by designing and testing
PI controllers for a set of operating conditions
Operation at different wind speed conditions.
Operation at different ramp increase in wind speed.
Operation at different step increases in wind speed.
Operation at 1-phase fault.
Operation at 3-phase fault.
Operation at different voltage sag conditions
Training was performed using Hybrid Algorithm
SIMULATION RESULTS FOR DFIG DURING THREE-PHASE
FAULT
q-axis Stator Current (pu)
d-axia Stator Current (pu)
4
ANFIS
PI
2
0
-2
-4
19.95
20
20.05
20.1
20.15
20.2
20.25
20.3
20.35
20.4
4
ANFIS
0
-2
-4
19.95
20.45
Time (s)
PI
2
20
20.05
20.1
2
1
0
-1
-2
ANFIS
-3
PI
-4
19.95
20
20.05
20.1
20.15
20.2
20.25
20.3
20.15
20.3
20.35
20.4
20.45
20.35
20.4
q-axis stator current
ANFIS
0
-2
-4
19.95
20.45
PI
2
20
20.05
20.1
20.15
20.2
20.25
20.3
20.35
20.4
20.45
Time (s)
q-axis rotor current
d-axis rotor current
2.5
2
PI
1.5
1
0.5
20
20.05
20.1
20.15
20.2
Time (s)
20.25
Stator flux
20.3
20.35
20.4
20.45
DC Link Voltage (pu)
3
ANFIS
Stator Flux (pu)
20.25
4
Time (s)
0
19.95
20.2
Time (s)
q-axis Rotor Current (pu)
d-axis Rotor Current (pu)
d-axis stator current
ANFIS
PI
2.5
2
1.5
1
19.95
20
20.05
20.1
20.15
20.2
Time (s)
20.25
DC link voltage
20.3
20.35
20.4
20.45
SIMULATION RESULTS FOR UA DURING THREE-PHASE
FAULT
q-axis Stator Current (pu)
d-axia Stator Current (pu)
0.5
ANFIS
PI
0
-0.5
-1
19.95
20
20.05
20.1
20.15
20.2
20.25
20.3
20.35
20.4
ANFIS
0.8
PI
0.6
0.4
0.2
0
-0.2
19.95
20.45
20
20.05
20.1
20.15
20.2
20.25
20.3
20.35
20.4
20.45
Time (s)
Time (s)
d-axis stator current
q-axis stator current
1
q-axis Rotor Current (pu)
d-axis Rotor Current (pu)
0
ANFIS
PI
0.5
0
-0.5
19.95
20
20.05
20.1
20.15
20.2
20.25
20.3
20.35
20.4
-0.2
-0.4
-0.6
-0.8
-1
-1.2
19.95
20.45
ANFIS
PI
20
20.05
Time (s)
20.1
20.15
20.2
20.25
20.3
20.35
20.4
20.45
Time (s)
d-axis rotor current
q-axis rotor current
Stator Flux (pu)
1
ANFIS
PI
0.8
0.6
0.4
0.2
19.95
20
20.05
20.1
20.15
20.2
Time (s)
20.25
Stator flux
20.3
20.35
20.4
20.45
DC Link Voltage (pu)
1.35
ANFIS
1.3
PI
1.25
1.2
1.15
1.1
19.95
20
20.05
20.1
20.15
20.2
20.25
Time (s)
DC link voltage
20.3
20.35
20.4
20.45
Inferences
The dynamic performance shows that, with ANFIS, the settling
time is reduced, peak overshoot of values are limited and
oscillations have been damped out quickly.
ANFIS based controller performs better than PI controller.
ANFIS based controllers can perform more better by rigorous
training using large data sets.
Economic Issues
High capital/Energy Cost
Trading Issues
Fixed Price Systems where the government sets the
electricity prices (or premiums) paid to the producer and
allows the market to determine the quantity.
1. Investment Subsidies
2. Fixed Feed-in Tariffs
3. Fixed Premium Systems
4. Tax Credits.
Renewable Quota Systems where the government sets
the quantity of electricity from renewables and leaves it
to the market to determine the price.
Trading of Wind Power
Due to high cost and intermittent nature of availability
of wind power, it is not possible for wind generators
to bid into the competitive electricity market.
Therefore, Pricing mechanism for financial viability of
wind power in the market is necessary.
but
Trading of Wind Power-External Cost
The real cost of energy production by conventional
energy includes expenses absorbed by society,
such as health impacts and local and regional
environmental degradation – from mercury pollution
to acid rain – as well as global impacts from
climate change.
If these environmental costs were levied on electricity
generation according to their impact, many
renewables, including wind power, would not need
any support to successfully compete in the
marketplace.
Trading of Wind Power
Trading Issues will be examined and suitable market
mechanism will be developed to take care
of
survival of wind generators in Emerging Electricity
Market.
Both the demand and supply side bidding scenarios will
be considered with examples.
Several other considerations in market mechanism such
as market collusion, participation in the ancillary
services and impact on market power will also be
explored
Economic Issues
Preferential Tariff & Incentives
Complementary Mechanism
The beneficiaries shall pay to the respective ISGS Capacity
charges corresponding to plant availability and/or Energy charges
for the scheduled dispatch, in accordance with the relevant contracts
/orders of CERC.
The sum of the above two charges from all beneficiaries shall
fully reimburse the ISGS for generation according to the given
dispatch schedule. In case of a deviation in actual generation from
the dispatch schedule, the concerned ISGS shall receive or shall pay
in accordance with UI regulation of CERC.
Unschedule Interchange
‘Unscheduled Interchange’ in a time-block for a generating
station or a seller means actual generation minus its
scheduled generation and for a beneficiary or buyer means its
total actual drawal minus its total scheduled drawal.
Limits on UI volume
The over-drawal of electricity by any beneficiary or a
buyer during a time-block shall not exceed 12% of the
scheduled drawal of such beneficiary or buyer or 150 MW
(whichever is lower), and 3% on a daily aggregate basis, for
all the time blocks when frequency is below 49.5 Hz.
Unschedule Interchange
Special dispensation for scheduling
of solar generation
The schedule of solar generation shall be given by the generator
based on availability of the generator, weather forecasting, solar
insolation, season and normal solar generation curve and shall be
vetted by the RLDC in which the generator is located and
incorporated in the inter-state schedule.
If RLDC is of the opinion that the schedule is not realistic , it may
ask the solar generator to modify the schedule.
Special dispensation for scheduling
of solar generation
In case of solar generation no UI shall be payable/receivable by Generator. The host state , shall
bear the UI charges for any deviation in actual generation from the schedule.
However, the net UI charges borne by the host State due to the solar generation, shall be shared
among all the States of the country in the ratio of their peak demands in the previous month based
on the data published by CEA , in the form of regulatory charge known as the Renewable
Regulatory Charge operated through the Renewable Regulatory Fund .
This provision is applicable ,with effect from 1.1.2011, for new solar generating plants with
capacity of 5 MW and above connected at connection point of 33 KV level and above and , who
have not signed any PPA with states or others as on the date of coming into force of this IEGC.
Illustrative examples for commercial
settlement for Solar Generation
Solar generator to give schedule to the concerned SLDC and RLDC.
Purchasing state to pay to solar generator at contracted rate for whatever powe
is generated by the solar generation.
Remaining under drawal / over-drawal to be settled in UI mechanism and RRF.
Illustrative examples for commercial
settlement for Solar Generation
Case 1: Actual as per generation schedule
Schedule Actual
( MW)
generation
(MW)
Implication
on
purchaser
Unscheduled Interchange (UI)
Implication on
host state
Implication on
solar Generator
5
Purchaser to pay
Solar Generator
for 5 MW at
contracted rate.
No implication
on host state.
No implication
on solar
generator.
5
Illustrative examples for commercia
settlement for Solar Generation
Case 2: Under Injection by the Solar Generator
Schedule
( MW)
Actual
generation
(MW)
Implication
on
purchaser
Unscheduled Interchange (UI)
Implication on
Implication on
host state
solar Generator
5
4
Payment to be
made by purchaser
for 4 MW (as per
actual) at
Contracted rate and
for 1 MW
to RRF at UI rate
For 1 MW UI
liability on the
host state, as a
result of under
generation by
the Solar
Generator
embedded in the
State system,
the same shall
be received by
the host state
from RRF at UI
rate.
No implication on
Solar generator.
Illustrative examples for commercia
settlement for Solar Generation
Case 3: Over Injection by the Solar Generator
Schedule Actual
( MW)
generation
(MW)
Implication on
Purchaser
Unscheduled Interchange (UI)
Implication on
host state
Implication on
solar Generator
5
To pay for 6 MW to
Solar generator
at contracted rate
Purchaser shall
receive payment for
1 MW from RRF at
contracted rate.
For 1 MW, UI
benefit for the
host State on
account of
overgeneration
by
solar generator to
be passed on to
the RRF at UI
rate
No implication on
Solar generator.
6
Illustrative examples for commercial
settlement for Wind Generation
Case 1: Actual as per generation schedule
Schedule Actual
( MW)
generation
(MW)
Implication
on
purchaser
Unscheduled Interchange (UI)
100
Purchaser
to pay
Wind
Generator
for 100
MW at
contracted
rate.
No implication
on host state.
100
Implication on
host state
Implication on
wind
Generator
No implication
on
wind generator.
Illustrative examples for commercial
settlement for Wind Generation
Case 2: Under Injection by the Wind Generator within 30 % variation
Schedule
( MW)
Actual
generation
(MW)
Implication
on
purchaser
Unscheduled Interchange (UI)
100
70
Payment to be made
by purchaser for 70
MW (as per actual)
at contracted
rate and
for 30 MW
to
Renewable
Regulatory
Fund
(RRF) at
UI rate of
his region.
For 30 MW UI
liability on the
host state, as a
result of under
generation by
the Wind
Generator
embedded in the
State system,
the same shall
be received by
the host state
from RRF.
Implication on
host state
Implication on
wind
Generator
No implication on
wind generator.
Illustrative examples for commercial
settlement for Wind Generation
ase 3: Under Injection by the Wind Generator beyond 30 % variation
Schedule
( MW)
Actual
generation
(MW)
Implication
on
purchaser
Unscheduled Interchange (UI)
Implication on
host state
Implication on
wind
Generator
100
60
To pay for 70 MW to
Wind generator (since, in
this range, the wind
Generator comes
under UI mechanism)
At contracted rate. 30
MW by purchaser
at UI rate in his Region,
to RRF
Out of 40 MW
liability of UI on
Host State on
account of
under
generation by
wind generator,
UI for 30 MW
shall be
received by the
host state from
RRF and UI of
10 MW would
be received
from the UI
pool.
UI rate for 10 MW
payable by Wind
Generator to UI Pool
Illustrative examples for commercial
settlement for Wind Generation
ase 4: Over Injection by the wind generator within 30% variation
Schedule
( MW)
Actual
generation
(MW)
Implication
on
purchaser
Unscheduled Interchange (UI)
Implication on
host state
Implication on
wind
Generator
100
130
To pay for 130 MW to
Wind generator
At contracted rate.
Purchaser shall
Receive payment
for 30 MW from RRF
at UI rate of his region.
For 30 MW, UI
benefit for the
host State on
account of
overgeneration
by
wind generator
to be passed on
to the RRF.
No implication on
wind generator.
Illustrative examples for commercial
settlement for Wind Generation
ase 5: Over Injection by the wind generator from 130% to 150 % generation
Schedule
( MW)
Actual
generation
(MW)
Implication
on
purchaser
Unscheduled Interchange (UI)
100
140
To pay for
130 MW at
contracted
rate.
Purchaser
shall
receive
payment
for 30 MW
from RRF
at UI rate
of his
region.
For 40 MW UI
benefit for the
Host State on
account of over
generation by
wind generator,
UI for 30 MW to
be passed on to
the RRF and UI
for 10 MW to be
passed to UI
pool.
Implication on
host state
Implication on
wind
Generator
UI for 10 MW to
be
received from UI
pool.
Illustrative examples for commercial
settlement for Wind Generation
ase 5: Over Injection by the wind generator beyond 150 %
Schedule
( MW)
Actual
generation
(MW)
Implication
on
purchaser
Unscheduled Interchange (UI)
Implication on
host state
Implication on
wind
Generator
100
160
To pay for
130 MW at
contracted
rate.
Purchaser
shall
receive
payment
for 30 MW
from RRF
at UI rate
of his
region.
For 60 MW
benefit for the
Host State from
UI Pool on
account of
higher
generation by
wind, UI for 30
MW to be
passed on to
RRF and UI for
30 MW to be
passed on to UI
pool.
UI for 20 MW to be
received by Wind
Generator from UI
Pool at the UI rate
applicable at that
particular time and
for 10 MW UI to be
received by Wind
Generator from UI
Pool at the UI rate
applicable for
frequency interval
below 50.02 and not
below 50.00 Hz.
Renewable Energy Certificate (Regulations 2010)
CERC makes the following regulations for the development of
market in power from Non Conventional Energy Sources by issuance
of transferable and saleable credit certificates.
The concept of renewable energy certificate seeks to address the
mismatch between availability of renewable energy sources and the
requirement of obligated entities to meet their renewable purchase
obligations.
The REC mechanism mainly aims at promoting investment in the
renewable energy projects and to provide an alternative mode to the
RE generators for recovery of their costs.
Renewable Energy Certificate (Regulations 2010)
Categories of Certificates:
(1) There shall be two categories of certificates, viz., solar certificates
issued to eligible entities for generation of electricity based on solar as
renewable energy source, and non-solar certificates issued to eligible
entities for generation of electricity based on renewable energy sources
other than solar:
(2) The solar certificate shall be sold to the obligated entities to enable them
to meet their renewable purchase obligation for solar, and non-solar
certificate shall be sold to the obligated entities to enable them to meet
their obligation for purchase from renewable energy sources other than
solar.
Renewable Energy Certificate (Regulations 2010)
Eligibility and Registration for Certificates:
Dealing in the certificates:
Pricing of Certificate:
Validity and extinction of Certificates:
Modeling Issues
 the model complexity depends on the target of the
investigations or intended application,
 the models shall be in agreement with the interface
of simulation tools,
 the level of detail representation of each component
should truly represent its physical phenomenon,
 appropriate simulation time-scale is crucial for
phenomenon under study
95
Modeling Issues
 aggregated wind park models, which represent a
whole wind park instead of only a single wind
turbine, must be suitably addressed to study the
impact of high penetration levels of wind power on
the dynamic behavior of large power systems, by
considering all parameters.
 this reduces the size of the power system model, the
data requirements and the computation time.
96
Modeling Issues
 Development
of
models
must
reflects
the
technological development (or next generation WT) in
the area of wind power generation especially in
meeting existing Grid Code Requirements (GCR) as
well as GCR’s required in future
 Reactive power capability of WT & inclusion of
FACTS devices
97
Conclusions
 Wind farms have a significant influence on the operation of
power systems.
 Grid codes are set up to specify the relevant requirements for
efficient and secure operation of power system for all network
users and these specifications have to be met in order to
integrate wind turbines into the grid.
 In this paper, existing GCR of several countries, which are
proactively meeting the challenge of considerable wind power
penetration, are analyzed.
Conclusions
 GCR’s are discussed, like, are active power control, frequency
control, voltage control, wind farm protection (fault ride
through control) etc.
 These interconnection regulations for wind turbines or wind
farms tend to add the following requirements:
• to maintain operation of WTduring a fault in the grid,
known as ‘fault ride-through’ capability;
• to operate the wind turbine in the predefined frequency range;
• to control the active power during frequency variations (active
power control);
Conclusions
• to limit the power increase to a certain rate (power ramp rate
control);
• to supply or consume reactive power depending on power
system requirements (reactive power control);
• to support voltage control by adjusting the reactive power,
based on grid measurements (voltage control).
These interconnection requirements can increase the total cost
of a wind turbine or wind farm. Hence, interconnection
regulations should be enforced for secure & economic
operation of power system.
Outlook (1)
Further increase of wind turbine size – limitation only by
transportation
DFIG or full size converter based wind turbines? Still not
clear!
Voltage control by WT becomes common feature
WT will be provide STATCOM function
WT stay connected to the grid during voltage dips
WT will participate in grid frequency support
Outlook (2)
Wind farm operators have to provide certification about grid
compliance
Standards for certification are necessary
Manufacturer have to provide WT simulation models for
grid studies
Further improvement of grid codes is necessary
Financial compensation for Var generation?
Outlook (3)
Wind Turbine modeling (DFIG)
• Model for stability studies
• Aggregated Model for Wind Farms/Parks
Impact of Large Wind Power on Transient Stability and
development of Controllers to improve Transient Stability
Impact of Large Wind Power on Small Signal Stability and
development of Controllers to improve Small Signal Stability
Coordination of Wind Power with Conventional Power Plants
Trading Issues and Development of Suitable Market Mechanism
for Emerging Electric Power System.
Future Perspective of Renewable Energy in India
Perspective Plan 2022
 The Integrated Energy Policy Report (IEPR), prepared
by the planning commission of India, has recognized
renewable energy sources remain important to Indian’s
energy sector.
 With a concerted push and a 40 fold increase in their
contribution to the primary energy, renewables may
account for only 5-6% of India’s energy mix by 2031-32.
 This will call for extensive RD&D efforts to make
renewable energy technologies more reliable, long life and
cost effective.
 The planning commission of India set a very competitive
goal for India in its perspective plan 2022.
Perspective Plan: Grid-Interactive Renewable Power
The aim for the 11th five year plan i.e (2007-12) is a capacity addition of 15000 MW
from RES (14000 MW Grid-interactive and 1000 MW distributed RES).
By the end of the 11th plan, renewable power capacity would be 25000 MW in a total
capacity of 200 GW accounting for 12.5% and contributing around 5% to the electricity
mix.
A capacity addition of around 30 GW is envisaged for the 12 th and 13th plans.
Renewable power capacity by the end of the 13th plan period is likely to reach 54000 MW,
comprising 40000 MW wind power, 6500 MW SHP, and 7500 MW bio-power, which
would correspond to a share of 5% in the then electricity-mix.
Resource
Upto 10th Plan
(2002-07)
11th Plan
(2007-12)
12th & 13th Plan
(2012-22)
Total
Wind Power
7000
10500
22500
40000
SHP
1960
1400
3140
6500
Bio Power
1037
2100
4363
7500
3
-
-
3
10000
14000
30003
54003
Solar Power
Total
Perspective Plan: Renewable Energy for Urban,
Industrial, and Commercial Applications
The major goals include 50 million m2 of solar collector area for thermal applications,
mainly solar water heating, and, 7500 MW of grid/captive power from bio-resources,
including urban and industrial wastes.
Compared to the status in 2007, there is a massive build-up in capacity, which will
require concerted action across various fronts, starting with the next plan.
Resource
Solar Thermal Systems /
Devices
2012
10 million m2
collector area
2022
30 million m2
2032
50 million m2
Energy-efficient Buildings
5 million m2
floor area
(1000 buildings)
20 million m2
40 million m2
Energy Recovery from
Included in the proposed targets for bio-power in gridUrban & Industrial Wastes interactive renewable power.
Medium Term (2032) Deployment Aims
GOI aims for several medium/long term goals such as 10% grid interactive renewable power
by 2012 and 15 % by 2032, alternate fuels (bio fuels, synthetic fuels, and hydrogen)
substitution up to 5% by 2017 and 10% by 2032. The other massive plans in various sectors
are
Energy recovery from municipal waste in 423 cities including 107 municipal corporations where
suitable waste is available by 2032.
Solar water heating systems: 100% coverage of all prospective users like hotels, hospitals,
etc. by 2032.
100% coverage of street lighting control systems by solar sensors in all cities by 2012.
Solar water heating systems: 100% coverage of potential industries by 2032.
Cogeneration: 100% coverage of potential sugar and other biomass based industries by 2032.
Provision of lighting/electricity in all remote un-electrified census villages and remote hamlets
of electrified census villages by 2012.
Concluding Remarks





India has huge potential for producing power from Renewable Energy
Sources (RES).
Government of India has endeavored to lay the foundation for a broadbased renewable energy program and designed it specially to meet the
growing energy needs, and to fulfill energy shortage and security concerns of
the country.
Considerable experience and capabilities exist in the country on renewable
technologies. Although at present the contribution of renewable energy is
small, but future developments might make RES technology more
competitive to displace conventional energy sources.
Prospects for RES are steadily improving in India towards a great future. It
is destined to take a leading role in the global renewable energy movement
aiming towards sustainable development.
The strategy for achieving these enhanced goals will mainly depend on the
active participation of all players i.e. from government agencies to NGO’s,
from manufactures to R&D institutions, from financial institution to
developers and of course a new breed of energy entrepreneurs.