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APPENDIX - I

A.1 STATIC SYNCHRONOUS COMPENSATOR

The Static Synchronous Compensator is a shunt connected reactive

compensation equipment which is capable of generating and/or absorbing

reactive power whose output can be varied so as to maintain control of

specific parameters of the electric power system.

A.1.1 Introduction and Basic Circuit Configuration

The STATCOM provides operating characteristics similar to a rotating

synchronous compensator without the mechanical inertia. As the STATCOM

employ solid state power switching devices, it provides rapid controllability

of the three phase voltages, both in magnitude and phase angle. The

STATCOM basically consists of a step-down transformer with a leakage

reactance, a three-phase GTO or IGBT voltage source inverter (VSI), and a

DC capacitor. The AC voltage difference across the leakage reactance

produces reactive power exchange between the STATCOM and the power

system, such that the AC voltage at the bus bar can be regulated to improve

the voltage profile of the power system, which is the primary duty of the

STATCOM.

However, for instance, a secondary damping function can be added

into the STATCOM for enhancing power system oscillation stability. A

STATCOM can be used for voltage regulation in a power system, having as

an ultimate goal the increase in transmittable power, and improvements of

steady-state transmission characteristics and of the overall stability of the

system. Under light load conditions, the controller is used to minimize or

completely diminish line over voltage. On the other hand, it can be also used

to maintain certain voltage levels under heavy loading conditions.

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Fig A.1.1 Connection of STATCOM to AC Bus bar

STATCOM consists of the coupling transformer, input filter, Voltage

Source Converter and a controller. The connection of STATCOM to AC bus

is shown in fig. A.1.1. When two AC sources of same frequency are

connected through a series inductance, active power flows from leading

source to lagging source and reactive power flows from higher voltage

magnitude AC source to lower voltage magnitude AC source. Active power

flow is determined by the phase angle difference between the sources and the

reactive power flow is determined by the voltage magnitude difference

between the sources. Hence, STATCOM can control reactive power flow by

changing the fundamental component of the converter voltage with respect to

the AC bus bar voltage both phase wise and magnitude wise.

Typical applications of STATCOM are:

1. Effective voltage regulation and control.

2. Reduction of temporary over voltages.

3. Improvement of steady-state power transfer capacity.

4. Improvement of transient stability margin.

5. Damping of power system oscillations.

6. Damping of sub synchronous power system oscillations.

7. Flicker control.

8. Power quality improvement.

9. Distribution system applications

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A.1.2 Basic Operating Principles of STATCOM

The basic electronic block of a STATCOM is a voltage-sourced

converter that converts a dc voltage at its input terminals into a three-phase

set of ac voltages at fundamental frequency with controllable magnitude and

phase angle [3]. The basic principle of reactive power generation by a

voltage-sourced converter is similar to that of the conventional rotating

synchronous machine shown schematically in fig A.1.2.

Fig. A.1.2 Reactive power generation by a synchronous compensator

For purely reactive power flow, the three-phase induced electromotive

forces, ea, eb, and ec, of the synchronous rotating machine are in phase with

the system voltages va, vb, and vc. The reactive current I drawn by the

synchronous compensator is determined by the magnitude of the system

voltage V, that of the internal voltage E, and the total circuit reactance

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(synchronous machine reactance plus transformer leakage reactance plus

system short circuit reactance ) X,

A.1.1

The corresponding reactive power Q exchanged can be expressed as follows

A.1.2

By controlling the excitation of the machine, and hence the amplitude

E of its internal voltage relative to the amplitude V of the system voltage, the

reactive power flow can be controlled. Increasing E above V (i.e. operating

over-excited) results in a leading current as a result machine acts as capacitor.

Decreasing E below V (i.e. operating under-excited) produces a lagging

current as a result machine acts as a inductor. Under either operating

condition a small amount of real power of course flows from the ac system to

the machine to supply its mechanical and electrical losses. Note that if the

excitation of the machine is controlled so that the corresponding reactive

output maintains or varies a specific parameter of the ac system (e,g., bus

voltage), then the machine ( rotating var generator) functions as a rotating

synchronous compensator. The basic voltage-sourced converter scheme for

reactive power generation is shown schematically, in the form of a single-line

diagram in fig A.1.3.

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Fig A.1.3 Reactive power generation by controlled voltage-sourced switching converter

From a dc input voltage-sourced, provided by the charged capacitor

Cs, the convertor produces a set of controllable three-phase output voltages

with the frequency of the ac power system. Each output voltage is in phase

with, and coupled to the corresponding ac system voltage via a relatively

small (0.1 – 0.15 p.u.) tie reactance (which in practice is provided by the per

phase leakage inductance of the coupling transformer). By varying the

amplitude of the output voltage produced, the reactive power exchange

between the converter and the ac system can be controlled in a manner similar

to that of the rotating synchronous machine. That is, if the amplitude of the

output voltage is increased above that of ac system voltage, then the current

flows through the tie reactance from the converter to the ac system, and the

converter generates reactive (capacitive) power for the ac system. If the

amplitude of the output voltage is decreased below that of the ac system, then

reactive current flows from the ac system to the converter, and the converter

absorbs reactive (inductive) power. If the amplitude of the output voltage is

equal to that of the ac system voltage, the reactive power exchange is zero.

The three-phase output voltage is generated by a voltage-sourced dc to

ac converter operated from an energy storage capacitor. All of the practical

converters so far employed in actual transmission applications are composed

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of a number of elementary converters, that is, of single phase H-bridges, or

three-phase, two-level, six-pulse bridges, or three-phase, three-level, 12- pulse

bridges shown in fig A.1.4

Fig A.1.4 Basic converter schemes used for reactive power generation

The valves used in the elementary converter usually comprise a

number of series connected power semiconductors, e.g., GTO thyristors with

reverse-parallel diodes. Each elementary converter produces a square or a

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quasi-square or a pulse-width modulated output voltage waveform. These

component voltage waveforms are phase-shifted from each other (or

otherwise made complementary to each other) and then combined, usually

with the use of appropriate magnetic components, to produce the final output

voltage of the total converter. With sufficient design, this final output voltage

can be made to approximate a sine wave closely enough so that no filtering is

required.

The operation of the voltage-sourced converter, used as a controllable

static var generator, can be explained without considering the detailed

operation of the converter valves by basic physical laws governing the

relationship between the output and input powers. The key to this explanation

in the physical fact that, like in all switching power converters, the net

instantaneous power at the ac output terminals must always be equal to the net

instantaneous power at the dc input terminal (neglecting the losses in the

semiconductor switches). Since the converter supplies only reactive output

power (its output voltages are controlled to be in phase with the ac system

voltages), the real power provided by the dc source (charged capacitor) must

be zero (as the total instantaneous power on the ac side is also zero).

Furthermore, since reactive power at zero frequency (at the dc capacitor) by

the definition is zero, the dc capacitor plays no part in the reactive power

generation. In other words the converter simply interconnects the three ac

terminals in such a way that the reactive output currents can flow freely

between them.

Viewing this from terminals of the ac system, one could say that the

converter establishes a circulating current flow among the phase with zero net

instantaneous power exchange. The presence of the input ripple current

components is thus entirely due to the ripple components of the output

voltage, which are a function of the output waveform fabrication method

used. In a practical var generator, as explained above, the elementary two or

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three-level converters would not meet practical harmonic requirements either

for the output voltage or for the input (dc capacitor) current. However by

combining a number of these basic converters into a multi-pulse structure

(and / or using appropriate pulse-width modulation – PWM – or other wave

shaping techniques), the output voltage distortion and capacitor ripple can be

theoretically reduced to any desired degree. Thus, a static (var) generator,

employing a perfect voltage-sourced converter, would produce sinusoidal

output voltages, would draw sinusoidal reactive currents from the ac system

and zero input current from the dc capacitor. In practice due to system

unbalance and other imperfections (which could increase the ac power

fluctuation considerably), as well as economic restrictions, these ideal

conditions are not achieved, but can be approximated quite satisfactory by

appropriate converter structures and wave shaping techniques so that the size

of the dc capacitor in normal transmission applications remains relatively

small.

In a practical converter, the semi converter switches are not lossless,

and therefore the energy stored in the dc capacitor would be used up by the

internal losses. However these losses can be supplied from the ac system by

making the output voltages of the converter lag the ac system voltages by a

small angle. In this way the converter absorbs a small amount of real power

from the ac system to replenish its internal losses and keep the capacitor

voltage at the desired level. The mechanism of phase angle adjustment can

also be used to control the var generation or absorption by increasing or

decreasing the capacitor voltage, and thereby the amplitude of the output

voltage produced by the converter. The capacitor also has a vital function

even in the case of a converter, in establishing the necessary energy balance

between the input and output during the dynamic changes of the var output.

It is, of course, also possible to equip the converter with the dc source

(e,g., a battery) or with an energy storage device of significant capacity (e.g.,

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a large dc capacitor, or a superconducting magnet). In this case the converter

can control both reactive and real power exchange with the ac system, and

thus it can function as a static synchronous generator. The capability of

controlling real as well as reactive power exchange is a significant feature

which can be used effectively in applications requiring power oscillation

damping, leveling peak power demand, and providing uninterrupted power

for critical loads. This capability is unique to the switching converter type var

generator and it fundamentally distinguishes it from its conventional thyristor-

controlled counterpart.

A.1.3 Modeling of STATCOM

The STATCOM is modeled by a voltage source connected to the

power system through a coupling transformer. The source voltage is the

output of a voltage-sourced converter realizing the STATCOM. From the fig.

A.1.5 STATCOM is considered at the midpoint of the transmission line. The

phase angle of the source voltage is equal as that of the midpoint voltage.

Therefore, there is exchange of only reactive power and no real power

between the STATCOM and the ac system [3],[20].

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Fig. A.1.5 Representation of STATCOM

The expressions for the current flowing from the STATCOM to the

system and the reactive power injection are given as

A.1.3

A.1.4

Where Vm is the magnitude of the voltage at the midpoint of the line

and Vsc is the magnitude of the voltage of the voltage-sourced converter, Vm

is the phase angle of the midpoint voltage, and Xl is the coupling transformer

leakage reactance. The magnitude of the voltage of the voltage-sourced

converter determines the direction and nature of the reactive power flow. If it

is greater than the magnitude of the line midpoint voltage, then reactive power

is injected to the ac system, whereas if the line midpoint voltage magnitude is

greater, then reactive power will be drawn from the ac system. Here only the

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reactive power injection mode of operation is considered. The leakage

reactance of the coupling transformer is taken as 0.1 p.u. During fault

conditions a constant value of source voltage magnitude may cause a very

high value of current drawn from the STATCOM (Isc). For this, a maximum

limit, denoted by Imax, is set for the STATCOM current. For a practical

system, this current limit is decided by the rating of the STATCOM. When

the current reaches the limit Imax, STATCOM behaves like a constant current

source. To include this feature in the simulation, Vsc is kept constant at the

pre-specified value (denoted by Vsco) when Isc ≤ Imax. But, whenever the value

of Isc exceeds Imax, the value of Vsc is adjusted such that Isc becomes equal to

Imax. The STATCOM is used to control power flow of power system by

injecting appropriate reactive power during dynamic state. The STATCOM is

a voltage-sourced-converter (VSC)-based shunt-connected device. By

injecting a current of variable magnitude in quadrature with the line voltage,

the STATCOM can inject reactive power into the power system. The

STATCOM does not employ capacitor or reactor banks to produce reactive

power as does the SVC, but instead uses a capacitor to maintain a constant dc

voltage for the inverter operation.

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APPENDIX - II

A.2.1 SOLAR ENERGY

The average intensity of light outside the atmosphere (known as the

solar constant) is near to 1353 W/m2. Attenuation by the atmosphere results in

peak intensity at sea level of around 1 kW/m2, giving a 24 hour annual

average of 0.2 kW/m2 averaged over the planet’s surface. As this overall

energy density is relatively small, large areas will be required for a significant

energy production.

Irradiation varies regionally, with the changing season, and hourly with

the daily variation of the sun’s elevation. Many locations do not experience

unbroken sunshine. Cloud cover can significantly reduce the net radiation and

cause relatively fast variations in intensity. In some cases it could even lead to

significant variations from minute to minute or even over seconds. The earth’s

tilt angle leads to a variation of the seasonal irradiance. Generally speaking,

the irradiation reduces further the distance away from the equator. It can be

well below 100 W/m2 on a 24 hour average. Obviously, these values are

averaged over the year and will vary significantly with the seasons.

Fig A 2.1 Cumulative capacity of PV installations in the world and in the U.S.

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Major advantages of solar power are:

• Short lead times to design, install, and start up a new plant

• Highly modular; hence, the plant economy is not strongly dependent

on size

• Power output matches very well with peak-load demands

• Static structure, no moving parts; hence, no noise

• High power capability per unit of weight

• Longer life with little maintenance because of no moving parts

• Highly mobile and portable because of light weight

At present, PV power is extensively used in stand-alone power systems

in remote villages around the world, particularly in hybrid systems with diesel

power generators. It is expected that this application will continue to find

expanding markets in many countries. The driving force is the energy need in

developing countries and the environmental concerns in developed countries.

TYPES OF SOLAR POWER SYSTEMS

• Concentrating solar power

• Photo voltaic array solar power

A.2.1.1 Concentrating Solar Power System

Concentrating Solar Power (CSP) systems use lenses or mirrors and

tracking systems to focus a large area of sunlight into a small beam. The

concentrated heat is then used as a heat source for a conventional power plant.

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A wide range of concentrating technologies exists; the most developed are the

parabolic trough, the concentrating linear Fresnel reflector, the Sterling dish

and the solar power tower. Various techniques are used to track the Sun and

focus light. In all of these systems a working fluid is heated by the

concentrated sunlight, and is then used for power generation or energy storage

A parabolic trough consists of a linear parabolic reflector that

concentrates light onto a receiver positioned along the reflector's focal line.

The receiver is a tube positioned right above the middle of the parabolic

mirror and is filled with a working fluid. The reflector is made to follow the

Sun during the daylight hours by tracking along a single axis. Parabolic

trough systems provide the best land-use factor of any solar technology. The

SEGS plants in California and Acciona's Nevada Solar near Boulder City,

Nevada are representatives of this technology. The Suntrof-Mulk parabolic

trough, developed by Melvin Pruett, uses a technique inspired by Archimedes'

principle to rotate the mirrors.

Concentrating linear Fresnel reflectors are CSP-plants which use many

thin mirror strips instead of parabolic mirrors to concentrate sunlight onto two

tubes with working fluid. The advantage is that flat mirrors can be used which

is much cheaper than parabolic mirrors, and that more reflectors can be placed

in the same amount of space, allowing more of the available sunlight to be

used. Concentrating linear Fresnel reflectors can be used in either large or

more compact plants.

A Stirling solar dish or dish engine system, consists of a stand-alone

parabolic reflector that concentrates light onto a receiver positioned at the

reflector's focal point. The reflector tracks the Sun along two axes. Parabolic

dish systems give the highest efficiency among CSP technologies. The 50 kW

Big Dish in Canberra, Australia is an example of this technology. The Stirling

solar dish combines a parabolic concentrating dish with a Stirling heat engine

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which normally drives an electric generator. The advantages of Stirling solar

over photovoltaic cells are higher efficiency of converting sunlight into

electricity and longer lifetime.

A solar power tower uses an array of tracking reflectors (heliostats) to

concentrate light on a central receiver atop a tower. Power towers are more

cost effective, offer higher efficiency and better energy storage capability

among CSP technologies. The Solar Two in Barstow, California and the Plant

Solar 10 in Sanlucar la Mayor Spain are representatives of this technology.

A.2.1.2 Photo Voltaic Array Solar Power

A solar cell or Photo Voltaic cell, is a device that converts light into

electric current using the photoelectric effect. The first solar cell was

constructed by Charles Frits in the 1880s.Although the prototype selenium

cells converted less than 1% of incident light into electricity, both Ernst

Werner von Siemens and James Clerk Maxwell recognized the importance of

this discovery. Following the work of Russell Ohl in the 1940s, researchers

Gerald Pearson, Calvin Fuller and Daryl Chapin created the silicon solar cell

in 1954.These early solar cells cost 286 USD/watt and reached efficiencies of

4.5–6%.

There are many competing technologies, including fourteen types of

photovoltaic cells, such as thin film, monocrystalline silicon, polycrystalline

silicon, and amorphous cells, as well as multiple types of concentrating solar

power. It is too early to know which technology will become dominant.

The earliest significant application of solar cells was as a back-up

power source to the Vanguard-I satellite in 1958, which allowed it to continue

transmitting for over a year after its chemical battery was exhausted. The

successful operation of solar cells on this mission was duplicated in many

other Soviet and American satellitesand by the late 1960s, PV has become the

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established source of power for them. Photo voltaic plays an essential part in

the success of early commercial satellites such as Telstar, and they remain

vital to the telecommunications infrastructure today.

A.2.2 WIND ENERGY

Winds result from the large scale movements of air masses in the

atmosphere. These movements of air are created on a global scale primarily

by differential solar heating of the earth’s atmosphere. Therefore, wind

energy, is also an indirect form of solar energy. Air in the equatorial regions is

heated more strongly than at other latitudes, causing it to become lighter and

less dense. This warm air rises to high altitudes and then flows northward and

southward towards the poles where the air near the surface is cooler. This

movement ceases at about 30° N and 30° S, where the air begins to cool and

sink and a return flow of this cooler air takes place in the lowest layers of the

atmosphere.

The areas of the globe where air is descending are zones of high

pressure. Conversely where air is ascending, low pressure zones are formed.

This horizontal pressure gradient drives the flow of air from high to low

pressure, which determines the speed and initial direction of wind motion.

The greater the pressure gradient, the greater is the force on the air and the

higher is the wind speed. Since the direction of the force is from higher to

lower pressure, the initial tendency of the wind is to flow perpendicular to the

isobars (lines of equal pressure). However, as soon as wind motion is

established, a deflective force is produced due to the rotation of the earth,

which alters the direction of motion.

In addition to the main global wind systems there is also a variety of

local effects. Differential heating of the sea and land also causes changes to

the general flow. The nature of the terrain, ranging from mountains and

164

valleys to more local obstacles such as buildings and trees, also has an

important effect.

The boundary layer refers to the lower region of the atmosphere where

the wind speed is retarded by frictional forces on the earth’s surface. As a

result wind speed increases with height; this is true up to the height of the

boundary layer, which is at approximately 1000 meters, but depends on

atmospheric conditions. Wind farms can produce energy at costs comparable

to those of the most economic traditional generators. Due to advances in

technology, the economies of scale, mass production and accumulated

experience over the next decade, wind power is the renewable energy form

likely to make the greatest contribution to electricity production.

Fig 5.1 Worldwide installed wind-power capacity

Wind Energy in India

In 2012, despite a slowing global economy, India’s electricity demand

continued to rise. Electricity shortages are common, and over 40% of the

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population has no access to modern energy services. India’s electricity

demand is projected to more than triple between 2005 and 2030. In the

recently released National Electricity Plan (2012) the Central Electricity

Authority projected the need for 350-360 GW of total generation capacity by

2022. Despite major capacity additions over recent decades, power supply

struggles to keep up with demand.

India had another record year of new wind energy installations

between January and December 2011, installing more than 3 GW of new

capacity for the first time to reach a total of16,084 MW. As of March 2012,

renewable energy accounted for 12.2 percent of total installed capacity, up

from 2 percent in 1995. Wind power accounts for about 70 percent of this

installed capacity. By the end of August 2012, wind power installations in

India had reached 17.9 GW.

Under the New Policies Scenario of the World Energy Outlook(2011),

total power capacity in India would reach 779 GW in 2035. To reach 779 GW

in 2035, capacity must grow at a CAGR of 5.9 percent, or over 20 GW per

year from 2009through 2035. The largest addition per year up to now was

nearly 18 GW during fiscal year 2011-2012; this scale of expansion could

pose a challenge for the government [IEA,2012] without a significant role for

renewables. During fiscal year 2011-2012 wind energy alone delivered over

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3GW to India’s new installed capacity, accounting for over 16.5percent of

total new installed capacity.

Renewable Energy in the 12th Five-Year Plan[2012-2017]

Historically, wind energy has met and often exceeded the targets set

for it under both the 10th Plan (2002-2007) and11th Plan (2007-2012)

periods. During the 10th Plan period the target set was of 1,500 M W whereas

the actual installations were 5,427 MW. Similarly during the 11th Plan period

the revised target was for 9,000 MW and the actual installations were much

higher at 10,260 MW.

The report of the sub-group for wind power development appointed by

the Ministry of New and Renewable Energy to develop the approach paper for

the 12th Plan period (April 2012to March 2017) fixed a reference target of

15,000 M W in new capacity additions, and an aspirational target of 25,000

MW.

Importantly the report recommends the continuation of the Generation

Based Incentive scheme during the 12th Plan period. The report also

prioritized the issue of transmission, which was a weak link in the value chain

until now. A joint working group of the MNRE, the Ministry of Power, the

Central Electricity Authority and the Power Grid Corporation of India is

looking at this issue.

However, for India to reach its potential and to boost the necessary

investment in renewable energy it will be essential to introduce

comprehensive, stable and long-term support policies, carefully designed to

ensure that they operate in harmony with existing state level mechanisms so

as to avoid reducing their effectiveness.

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Wind Power Resource Assessment

Presently, India has an installed power generation capacity of a little

over 207.8 GW, of which renewables account for about 25 GW, and wind

makes up a majority of this installed capacity.

In 2011 the state-run Centre for Wind Energy Technology reassessed

India’s wind power potential as 102,778 MW at80 metres height at 2% land

availability6, up from the earlier estimate of approximate 49,130 MW at 50

metres, also at 2%land availability7. If the estimated potential of 102 GW

were fully developed, wind would provide only about 8 percent of the

projected electricity demand in 2022 and 5 percent in2032 [LBNL 2012].

Over the past year other research organizations have estimated wind

potential using differing models for mapping the wind resource. In one such

study, conducted by the Lawrence Berkeley National Laboratory, assuming a

turbine density of 9 MW/km2, the total wind potential in India with a

minimum capacity factor of 20 percent ranges from 2,006 GW at 80-meter

hub-height to 3,121 GW at 120-meterhub-height.

These research studies need ground level validation through long-term

wind measurements at 80 and 120-meter hub height. Nevertheless their

findings may have a significant impact on India’s renewable energy strategy

as it attempts to cope with a substantial and chronic shortage of electricity.

In a positive development the Ministry of New and Renewable Energy

(MNRE), has now signed a Memorandum of understanding with the

Lawrence Berkeley Lab to collaborate on several issues related to the

estimation of wind resource potential and grid integration.

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Wind Power Installations by State

Historically, the States of Tamil Nadu, Karnataka, Maharashtra and

Gujarat have been the leaders in terms of total wind installations. The States

of Rajasthan, Madhya Pradesh and Kerala are quickly catching up. By the end

of the 11th Plan period in March of 2012, the total installed capacity had

reached a total of 17,351.6 MW.

Interestingly more than 95 percent of the nation’s wind energy

development to date is concentrated in just five states in southern and western

India – Tamil Nadu, Andhra Pradesh, Karnataka, Maharashtra, and Gujarat

[LBNL, 2012]. These five states accounted for over 85% of the total installed

capacity at the end of the last plan period. Rajasthan is another emerging State

with rising wind turbine installations.

Table A 2.1 Installed Wind power capacity between 01.04.2011 to 31.03.2012

State Annual Installations (MW)

Cumulative Installations (MW)

Andhra Pradesh 54.1 245.5

Gujarat 789.0 2966.3

Karnataka 206.7 1933.5

Kerala 0 35.1

Madhya Pradesh 100.5 376.4

Maharashtra 416.75 2733.3

Rajasthan 545.7 2070.7

Tamil Nadu 1083.5 6987.6

Others 0 3.2

Total 3197.15 17351.6

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Offshore wind power development

India has a long coastline of over 7500 kilometers. In April2012, the

Ministry for New and Renewable Energy constituted an Offshore Wind

Energy Steering Committee13 under the chairmanship of the Secretary,

MNRE, to drive offshore wind power development in India in a planned

manner.

The Government is looking to prepare a time-bound action plan for

development of offshore wind energy, especially in the coastal states of

Andhra Pradesh, Gujarat, Maharashtra, Odisha, Kerala, Karnataka, West

Bengal and Tamil Nadu. A policy and guidelines for offshore wind are likely

to be announced by the Ministry of New and Renewable Energy in the near

future.

The State of Tamil Nadu is likely to take a lead in harnessing its

offshore wind resources and is in the process of installing a 100-metre mast

for wind measurements in Dhanushkodi. According to C-WET, as per the

preliminary assessment conducted by the Scottish Development

International14 (SCI),Tamil Nadu has a potential of about 1 GW in the north

of Rameswaram and another 1 GW in the south of Kanyakumari.SCI, under

the guidance of Centre for Wind Energy Technology conducted a detailed

survey of the region to assess various parameters required for installing

offshore wind farms. The technical feasibility study looked at offshore wind

energy potential in favourable areas in the southern Peninsula and Kutch

region in Gujarat. In a recent study conducted by WISE, the offshore wind

potential of Tamil Nadu has been estimated as 127 GW at 80 m height15,

which will need further validation.

170

Wind Power Density Map at 80 metres (W/m2)

171

Wind Power Density Map

172

Solar Density Map

173

State wise comparison of feed-in tariff policy for wind power

173

174

Global Cumulative Wind Power Capacity in MW

174

175

India: cumulative wind power capacity in MW

175

176

State wise comparison of wind power development

176

177

Average Capacity Factors In Key States

177

178

State Level Grid Interconnection, Metering Practices and Charges

178

179

Sourcewise and Statewise Estimated Potential of Renewable Power in

India as on 31.03.2011

180

181

182

Regionwise and Statewise Installed Generating Capacity of Electricity (Utilities) in India as on 31.03.2010 and 31.03.2011

183

Statewise and Sourcewise Installed Capacity of Grid Interactive

Renewable Power as on 31.03.2010 and 30.03.2011

184

(contd):Statewise and Sourcewise Installed Capacity of Grid Interactive Renewable Power as on 31.03.2010 and 30.03.2011

185

186

187

Installation of Off-grid / Decentralised Renewable Energy Systems/ Devices as on 31.03.2011

188

(contd..) : Installation of Off-grid / Decentralised Renewable Energy Systems/ Devices as on 31.03.2011

189

APPENDIX – III

PV SOLAR GLOSSARY

ANGLE OF INCIDENCE - The angle between the direct solar beam

and the normal (90 degrees) to the active surface.

ARRAY - Any number of Photovoltaic modules connected together

electrically to provide a single electrical output. An array is a mechanically

integrated assembly of modules or panels together with support structure

(including foundation and other components, as required) to form a free-

standing field installed unit that produces DC power.

AZIMUTH Angle between the north direction and the projection of

the surface normal into the horizontal plane; measured clockwise from north.

As applied to the PV array, 180 degree azimuth means the array faces due

south.

BALANCE OF SYSTEMS (BOS) Parts or components of a

photovoltaic system other than the photovoltaic array.

BLOCKING DIODE A semiconductor connected in series with a

solar cell or cells and a storage battery to keep the battery from discharging

through the cell when there is no output, or low output, from the solar cell. It

can be thought of as a one-way valve that allows electrons to flow forwards,

but not backwards.

CATHODIC PROTECTION Systems that protect underground

metal from corrosion by running small electrical currents along the metal.

Most often used to protect well heads, oil, gas, and water pipelines.

CELL (battery) A single unit of an electrochemical device capable of

producing direct voltage by converting chemical energy into electrical energy.

190

A battery usually consists of several cells electrically connected together to

produce higher voltages. (Sometimes the terms cell and battery are used

interchangeably).

CELL (solar) The smallest, basic Photovoltaic device that generates

electricity when exposed to light.

CHARGE RATE The current applied to a cell or battery to restore its

available capacity. This rate is commonly normalized by a charge control

device with respect to the rated capacity of the cell or battery.

CHARGE CONTROLLER A component of photovoltaic system that

controls the flow of current to and from the battery to protect the batteries

from over-charge and over-discharge. The charge controller may also indicate

the system operational status.

CONCENTRATOR A photovoltaic module which includes optical

components, such as lenses, to direct and concentrate sunlight onto a solar cell

of smaller area. Most concentrator arrays must directly face or track the sun.

DEPTH OF DISCHARGE (DOD) The ampere-hours removed from

a fully charged cell or battery, expressed as a percentage of rated capacity.

For example, the removal of 25 ampere- hours from a fully charged 100

ampere-hours rated cell results in a 25% depth of discharge. Under certain

conditions, such as discharge rates lower than that used to rate the cell, depth

of discharge can exceed 100%.

DIFFUSE INSOLATION The radiant energy from the sky incident

upon unit surface area during a specified time period (Same units as for direct

insolation).

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DIRECT INSOLATION The radiant energy from the sun (and a

small area of sky surrounding it, defined by the acceptance angle of the

pyrheliometer) incident upon unit surface area during a specified time period.

(MJ/m2 per hour, day, week, month or year, as the case may be).

EFFICIENCY The ratio of power output of a Photovoltaic cell to the

incident power from the sun or simulated sun sources under specified

standard insolation conditions.

ELECTROLYTE The fluid used in batteries as the transport medium

for positively and negatively charged ions.

EQUALIZATION The process of restoring all cells in a battery to an

equal state-of-charge. For lead-acid batteries, this is a charging process

designed to bring all cells to 100% state-of- charge. Some battery types may

require a complete discharge as a part of the equalization process.

EQUALIZING CHARGE A continuation of normal battery charging,

at a voltage level slightly higher than the normal end-of-charge voltage, in

order to provide cell equalization within a battery.

FLOAT SERVICE A battery operation in which the battery is

normally connected to an external current source; for instance, a battery

charger which supplies the battery load under normal conditions, while also

providing enough energy input to the battery to make up for its internal

quiescent losses, thus keeping the battery always up to full power and ready

for service.

FULL SUN The full sun condition is the amount of power density

received at the surface of the earth at noon on a clear day – about 100

mW/cm2. Lower levels of sunlight are often expressed as 0.5 sun or 0.1 sun.

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A figure of 0.5 sun means that the power density of the sunlight is one-half of

that of a full sun.

GASSING The evolution of gas from one or more of the electrodes in

the cells of a battery. Gassing commonly results from local action self

discharge) or from the electrolysis of water in the electrolyte during charging.

HERMETIC SEAL Being impervious to external influences.

Typically associated with the sealing of a package so that oxygen, moisture,

and other outside environments cannot enter the package.

HYBRID SYSTEM A power system consisting of two or more power

generating subsystems (e.g., the combination of a wind turbine or diesel

generator and a photovoltaic system.

INCIDENT LIGHT The incident light is the amount of light reaching

an object.

INSOLATION The amount of sunlight reaching an area. Usually

expressed in milliwatts per square centimeter, or langleys.

JUNCTION DIODE–A semiconductor device with a junction and a

built-in potential that passes current better in one direction than the other. All

solar cells are junction diodes.

MAXIMUM POWER The power at the point on the current-voltage

characteristic where the product of current and voltage is a maximum

(measured in watts).

MODULE The smallest non divisible, self-contained and

environmentally protected physical structure housing interconnected

Photovoltaic cells and providing a single DC electrical output.

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MULTICRYSTALINE Material that is solidified at such as rate that

many small crystals (crystallites) form. The atoms within a single crystallite

are symmetrically arranged, whereas crystallites are jumbled together. These

numerous grain boundaries reduce the device efficiency. A material

composed of variously oriented, small individual crystals. (Sometimes

referred to as polycrystalline or semicrystalline).

OPEN CIRCUIT VOLTAGE (VOC) Voltage produced by a

Photovoltaic cell with no load applied when the cell is exposed to standard

insolation conditions, measured with a voltmeter.

PANEL A collection of one or more modules fastened together into a

single unit, often factory pre- assembled and wired, forming a field-installable

unit.

PEAK POWER POINT Operating point of the I-V (current-voltage)

curve for a Photovoltaic cell or module where the product of the current value

times the voltage value is a maximum.

PEAK WATTS The measurement of electricity produced by a solar

generator at noon on a sunny day, under predetermined standard conditions.

PHOTON The actual (physical) particle unit of light, as the electron is

of electric charge and the atom and molecule are of matter. Light has both

wave properties and particle properties. Violet light has relatively short

wavelength and higher energy in its photons; red light has longer wavelength,

lower-energy photons. The wavelength and/or energy spectrum of the sun

extends in both directions beyond the visible range of light, of course, and the

silicon module solar cell can capture some energy in both of these invisible

zones. Photons not captured by the cell are either reflected or converted to

heat in the solar array.

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PHOTOVOLTAIC CELL A device composed of specially prepared

semiconductor material or material combinations exhibiting the ability to

convert incident solar energy directly into electrical energy.

PHOTOVOLTAIC EFFECT The phenomenon that occurs when

photons, the “particles” in a beam of light, knock electrons loose from the

atoms they strike. When this property of light is combined with the properties

of semiconductors, electrons flow in one direction across a junction, setting

up a voltage. With the addition of circuitry, current will flow and electric

power will be available.

PHOTOVOLTAIC SYSTEM An installed aggregate of solar arrays

generating power for a given application. A system may include the following

sub-systems:

Support Foundation

Power conditioning and control equipment

Storage

Active Thermal control

Land security systems and buildings

Conduit/wiring

Instrumentation

POWER CONDITIONER The electrical equipment used to convert

power from a photovoltaic array into a form suitable for subsequent use.

Loosely, a collective term for inverter, transformer, voltage regulator and

other power controls.

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REGULATOR Prevents overcharging of batteries by controlling

charge cycle-usually adjustable to conform to specific battery needs.

SINGLE-CRYSTAL STRUCTURE A material having a crystalline

structure such that a repeatable or periodic molecular pattern exists in all three

dimensions.

SOLAR CELL The basic photovoltaic device which generates

electricity when exposed to sunlight.

SOLAR PANEL A collection of solar modules connected in series, in

parallel, or in series- parallel combination to provide greater voltage, current,

or power than can be furnished by a single solar module. Solar panels can be

provided to furnish any desired voltage, current, or power. They are made up

as a complete assembly. Larger collections of solar panels are usually called

solar arrays.

STAND-ALONE SYSTEM (SA) A system which operates

independently of the utility lines. It may draw supplementary power from the

utility but is not capable of providing power to the utility.

SULFATION The formation of lead-sulfate crystals on the plates of a

lead-acid battery. Commonly used to indicate the large crystals which form in

partially discharged cells as the result of temperature cycling. These large

crystals are more difficult to reduce by the charging current than are the

smaller crystals that result from normal and self-discharge reactions. Sulfating

can be caused by leaving the battery in a discharged state for long periods of

time.

TILT ANGLE A fixed angle measured from the horizontal to which a

solar array is tilted. The tilt angle is chosen to maximize the array output.

Depending upon latitude, season and time of day this angle will vary.

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TRACKING ARRAY An array that is mounted on a movable

structure that attempts to follow the path of the sun. Some tracking arrays are

single axis while others are dual.