Revision as of 01:02, 28 February 2011

1 Introduction
2 Horizontal Axis Wind Turbines
- 2.1 Onshore and Offshore Wind Turbines
- 2.2 Parts of a Horizontal Axis Wind Turbine
3 Electrical Generating Systems
4 Wind Turbine Control Systems
5 Taxonomy for Wind Turbines
- 5.1 Major IPC classes
- 5.2 Major Players
6 Like this report?
7 Doubly-fed Induction Generator
8 Market Research
9 Like this report?
10 Contact Dolcera

Introduction

Humans have been using wind power for at least 5000 BC to propel sailboats and sailing ships, and architects have used wind-driven natural ventilation in buildings since similarly ancient times. The use of wind to provide mechanical power came later.
Harnessing renewable alternative energy is the ideal way to tackle the energy crisis, with due consideration given to environmental pollution, that looms large over the world.

Renewable energy is also called "clean energy" or "green power" because it doesn’t pollute the air or the water. Wind energy is one such renewable energy source that harnesses natural wind power.

Brief History of Wind Energy

Although the use of wind power started around 5000 BC, but electric power generation through wind energy started in 18th century and increasing drastically in 19th and 20th centuries. A brief view on developments on wind power sector are listed below.

Fig 1 Development of wind power worldwide

1887 : Prof. James Blyth of Scotland used windmills for generating electricity.
1888 : Charles Brush developed the first wind-powered turbine that generated electricity in the United States based on emulated James Blyth work.
1927 : Joe Jacobs and Marcellus Jacobs improved the wind turbine generator for use in farms.
1931 : development of Darrieus wind turbine. It is a vertical axis turbine that rotates with wind from any direction.
1941: Largest mega watt range wind turbine was connected to the local electrical distribution system on the mountain known as Grandpa's Knob in Castleton, Vermont, USA.
1971: Denmark installed the first offshore wind farms
1990s: More than 2200 MW capacity of wind turbines are installed in california.
2003: the largest offshore wind farm North Hoyle was built in the United Kingdom.
2003-2010: Research is going is on wind turbines in blades structures, generators, operation and protection, efficiency of wind turbines.

Source: Wind Energy
The total installed wind power capacity from 2001 to 2010 is shown in fig. 1. All wind turbines installed by the end of year 2009 worldwide are generating 340 TWh per annum. The country wise share of wind energy by the end of year 2009 is shown in fig. 2.

Fig 2 Country share of total capacity

Source:World Wind Energy Report 2009

Working Principle of Wind Turbine

Wind is air in motion. It is a form of solar energy. Solar radiation heats every part of the Earth’s surface unevenly due to irregularities and rotation of earth. The flow of wind patterns are modified by the earth's terrain, bodies of water, and vegetative cover. When air moves, causing wind, it has kinetic energy. The kinetic energy of wind can be captured by a wind turbine and converted to other forms of energy such as electricity or mechanical power.

Fig 3 Wind turbine principle

Sources:Wind Energy Basics,How Wind Turbines Work

Horizontal Axis and Vertical Axis Wind Turbines

Wind turbines are mainly classified into two types based on the axis in which turbine rotates. They are Horizontal axis wind turbine and vertical axis wind turbine.

Horizontal axis wind turbines	Vertical axis wind turbines
It is mounted on top of a tower ,requires huge towers leads to complex in operation, maintanace and high intial costs. It operates only with upstream or down stream wind directions. It can be constructed in offshores. It produces large amount of electricity with high efficiency. Fig 4(a) Horizontal axis wind turbine	These are easy to build and maintain, safer, easier to transport and they can be mounted close to the ground. These can handle much turblence in wind than horizontal wind turbines. Mostly it can be constructed with two blades It operates with any direction of wind Production of electricity is less due to low wind speeds near to ground Fig 4(b)Vertical axis wind turbine

Source:Different types of wind turbines

Horizontal Axis Wind Turbines

Onshore and Offshore Wind Turbines

Onshore wind turbines	Offshore wind turbines
Advantages It requires cheaper foundations Easily intergrated with the electrical- grid network cheaper Installation and access during the construction phase. It can be operated and maintained easily and cheaply Source:Onshore Vs Offshore Wind Turbines	These are two types, namely Near shore and Off shore. Advantages: The roughness of the water surface is very low Wind and obstacles to the wind are less. so, large turbines can be installed Noise pollution is also not a factor because these are too far from shores Less affected to turbulance in wind and low wind shear
Disadvantages Neagtive visual impact or noise. Limted avaliability of lands Restrictions asscociated with obstructions like buildings, mountains, etc. Noise pollution Afftected to more turbulance Sources:Wind Power,Types of Wind Farms	Disadvantages: Installing offshore windturbines is much more complex and costly Connection to the utility grid is also much more complex and expensive Operation and maintanances is also a complex task with off shore wind turbines Source:Offshore Technology
Fig 5(a) Onshore Wind turbines	Fig5(b) Offshore wind turbines

Parts of a Horizontal Axis Wind Turbine

The basic parts of a horizontal axis wind turbine(HAWT) is foundation, tower, nacelle, Generator, Rotor Blades.

Fig 6 Wind turbine parts

Foundation: A very good foundation is required to support the tower and various parts of a wind turbine which weighs in tonnes.

Tower

A tower that supports the nacelle and rotor hub at its top. These are made from tubular steel, concrete, or steel lattice. Height of the tower is an important in design of HWAT. Because wind speed increases with height, taller towers enable turbines to capture more energy and generate more electricity. Generally output power of the wind system increase with increase in height and also reduces the turbulance in wind. The theoritical view of tower height versus power out is shown in figure 7 . click on the link to get more about towers Wind Turbine Towers

Fig 7 Tower height Vs Power output

Source:The Fundamentals of Wind Energy

Different types of wind turbine towers	Structure
Tubular Tower: They are constructed from rolled steel plates welded together with flanges top and bottom, being sprayed with several coats of gray weatherproof paint at the construction yard. They have doors top and bottom allowing entrance to the vertical ladders inside used to access the power cables and the yaw mechanism. There are also a set of vertical ladders on the outside of the tower accessing the nacelle for maintenance and other checks.	Fig 8(a) Tubular tower
Lattice tower: A Lattice tower can be constructed with perfectly shapped steel rods that are put together to form a lattice. These towers are very strong and inexpensive to manufacture and easy to transport and erect.	Fig 8(b) Lattice tower
Guyed wind tower: These are very strong and most economical when properly installed. But it requires more space around the tower for guy wires	Fig 8(c) Guy tower
Tilt up wind towers:These type of towers are used for consumer wind energy. These turbines have locking system, while working the turbine is locked. It can easily ulocked and lowered to ground to perform repairs.	Fig 8(d) Tiltup tower
Free standing tower:These can be used for small wind turbines with cautions.	Fig 8(e) Free stand tower

Sources:Winder Tower,Wind Towers

Blades

Wind turbine blades are used to extract the kinetic energy of wind and convert to mechanical energy. These blades are made up of fiber glass-reinforced polyester or wood-epoxy. Wind turbines have one or two or three or multiple blades based up on the construction. Most of the HAWT have three blades. These are connected to rotor hub. Multiple blade concept is used in earlier days for pumping water and grinding etc.

Single blade HAWT	Two blade HAWT	Three blade HAWT
It reduces the cost and weight of the turbine. These are rarely used due to tower shadow effects, needs counter weights on the other side of the blade, less stability. Fig 9(a) Single blade turbine	It requires more complex design due to sustain of wind shocks. It is also less stable. It saves the cost and weight of one rotor blade. Fig 9(b) Two blade turbine	Modern wind trubines uses three blade concept. Because this structure have hight strength to withstand heavy wind stroms. Less effect due to towe shadow. Produces high output Fig 9(c) Three blade turbine

Sources:Wind Turbine Blades,Wind Turbine Design Styles

Nacelle

A housing which contains all the components which is essential to operate the turbine efficiently is called a nacelle. It is fitted at the top of a tower and includes the gear box, low- and high-speed shafts, generator, controller, and brakes. A wind speed anemometer and a wind vane are mounted on the nacelle.

Fig 10 Internal nacelle structure

Hub A rotor hub is provided for coupling a wind turbine rotor blade and a shaft. The hub assembly consists of hub, bolts, blade bearings, pitch system and internals . Rotor hubs are made with welded sheet steel, cast iron, fored steel. The types of rotor hubs are

Hingeless hub
Teetering hub

Fig 11 Rotor hub

Drive shaft Drive shafts are a hollow or solid steel hardened shaft under very high stresses and considerable torque. Drive shafts are used to transfer rotational mechanical energy from blade hub to the generator to produce electricity. A wind turbine normally consists two shafts .

Main shaft: It is connected between blade hub and input to the gear box. It rotates at low speeds. So It is also called as 'low speed shaft'.

Generator shaft: It connects the gear box output to the generator input. It rotates at very high speed equals to the rating of the generator. It is also called 'high speed shaft'.

Fig 12 Shaft system

Gear box Gear box used in wind energy systems to change low speed high toque power coming from a rotor blade to high speed low torque power which is used for generator. It is connected in between main shaft and generator shaft to increase rotational speeds from about 30 to 60 rotations per minute (rpm) to about 1000 to 1800 rpm. Gearboxes used for wind turbine are made from superior quality aluminum alloys, stainless steel, cast iron etc.

The various gear boxes used in wind turbines are

Planetary Gearbox
Helical Gearbox
Worm Gearbox

Fig13 Gear box

Generator

The output rotational mechanical energy of the gear box is connected to the generator through generator shaft. It works on the principle of 'Faraday's law of electromagnetic induction". It converts mechanical energy into electrical energy.

Sources:Wind Power Turbines, Rotor Hub Assembly,Gearbox for Wind Turbines, A Wind Turbine,The Wind Turbine Yaw Mechanism

Anemometers

Wind speed is the most important factor for determing the power content in the wind. The power content in the wind is directly proportional to cube of the wind velocity. Measuring wind speed is important for site selection. The device which is used for measuring wind speed is called anemometer. These are usally located on top of the nacelle.

Fig 14 Anemometer & Wind vane

Source:Anemometer

Types of anemometers The various types of anemometers are used in measuring wind speed is shown in flow chart below.

Source: Wind Power Energy

Wind vane Wind vanes are used to measure the wind directions and communicates with the yaw system to orient the turbine properly with respective to wind directions, to extract maximum amount of power from wind. Wind turbines are oriented to upstream wind or down stream wind.

Source:A Wind Turbine

Yaw Mechanism

yaw mechanism turns the rotor into the upwind direction as the wind direction changes. Electric motors and gear boxes are used to keep the turbine yawed against wind. This can be also used as controlling mechanism during high wind speeds.

Fig 15 Yaw structure

Source:The Wind Turbine Yaw Mechanism

Electrical Generating Systems

The various types of electrical generators are used in wind energy systems are shown in figure.

Source:Wind Turbine Generators

The most commonly used generator systems applied in wind turbines are are explained below.

	Fixed speed generating systems	Variable speed generating systems	Doubly fed induction generator
Structure
Machines	SQIG	PMSG/WRSG/WRIG	DFIG
Advantages	* Simple and low cost * Low maintanace	* Complete control of real and reactive powers * High energy efficiency	* Reduced capacity converter * Decoupled control of active and reactive power flow * Smooth grid connection
Drawbacks	* No control on real and reactive power * Less optimum power extraction capability * Poor power factor * High mechanical stress on turbine mechanical components	* Additional cost of power electronics * Limited fault ride through capability	* Regular maintenance of slip ring and gearbox * Limited fault ride-through capability

Source:Inside wind turbines

Wind Turbine Control Systems

As the wind turbines increases in size and power, control systems plays a major role to operate wind turbines in safe region and also to improve efficiency and quality of power conversion. The main objectives of wind turbine control systems is

Energy capture : Operating the wind turbine to extract maximum amount of energy considering safe restrictions like rated power, rated speed, cut-out wind speed etc.,
Mechanical loads: protecting the systems from transient loads.
Power quality: Conditioning the generated power with grid interconnection standards.

The various control techniques used in wind turbines are shown in table below

Control System	Pitch contol	Yaw control	Stall control	Generator torque control
Description	A method of controlling the speed of a wind turbine by varying the orientation, or pitch, of the blades, and thereby altering its aerodynamics and efficiency. Fig 16(a) Pitch control Source:Blade Pitch Control	The rotation of horizontal axis wind turbine around its tower to orient the turbine in upwind or down wind direction. Fig 16(b) Yaw control Source:Wind Turbine Control Methods	Stall control works by increasing the angle at which the relative wind strikes the blades (angle of attack). As the wind speed increases drag force on the blade increase and lift force gets reduces, thus finally reduces the speed of turbine.A fully stalled turbine blade, when stopped, has the flat side of the blade facing directly into the wind. Compare with furling. Source:Stall-control basics	As the aerodynamic torque control changes, rotor speed changes. it changes the output power frequency. A frequency converter is connected in between generator and the network to maintain generator power constant. SourceWind Energy Control

Taxonomy for Wind Turbines

Major IPC classes

A majority of patents describing wind turbines or wind energy are classified in the following IPC classifications.

S.NO	IPC Classification	Description
1	F03D	WIND MOTORS
2	F16C	SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OF CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
3	F16H	GEARING
4	F03B	MACHINES OR ENGINES FOR LIQUIDS
5	H02K	DYNAMO-ELECTRIC MACHINES
6	H02P	CONTROL OR REGULATION OF ELECTRIC MOTORS, GENERATORS, OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
7	H02M	APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION
8	H02J	CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
9	G06F	ELECTRIC DIGITAL DATA PROCESSING
10	G05F	SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
11	H02H	EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS

Major Players

Major players in the Wind Energy sector include: General Electric, Vestas Wind Systems, Siemens AG, Mitsubishi Ltd, REPower Systems AG, Gamesa Innovation & Technology, Enercon, Nordex, Suzlon and Sinovel Wind Group Co. Ltd.

Like this report?

This is only a sample report with brief analysis
Dolcera can provide a comprehensive report customized to your needs

Buy the customized report from Dolcera
Patent Analytics Services	Market Research Services	Purchase Patent Dashboard
Patent Landscape Services	Dolcera Processes	Industry Focus
Patent Search Services	Patent Alerting Services	Dolcera Tools

Doubly-fed Induction Generator

The present study on the IP activity in the area of horizontal axis wind turbines with focus on Doubly-fed Induction Generator (DFIG) is based on a search conducted on Thomson Innovation.

Control patents

S No	Patent / Publication No.	Publication Date	Assignee / Applicant	Title
1	US6278211B1	02/08/01	SWEO EDWIN A	Brushless doubly-fed induction machines employing dual cage rotors
2	US6954004B2	11/10/05	SPELLMAN HIGH VOLTAGE ELECTRON	Doubly fed induction machine
3	US7411309B2	12/08/08	XANTREX TECHNOLOGY INC	Control system for doubly fed induction generator
4	US7485980B2	03/02/09	HITACHI LTD	Power converter for doubly-fed power generator system
5	US7800243B2	21/09/10	VESTAS WIND SYS AS	Variable speed wind turbine with doubly-fed induction generator compensated for varying rotor speed
6	US7830127B2	09/11/10	WIND TO POWER SYSTEM S L	Doubly-controlled asynchronous generator

Thomson Innovation Search

A search is carried out using a combination of keywords and classifications in Thomson Innovation. The Classifications identified relevant to the scope of the search are:

IPC/ ECLA Classes

IPC/ ECLA Class	Definition
F03D9/00	Adaptations of wind motors for special use; Combinations of wind motors with apparatus driven thereby (aspects predominantly concerning driven apparatus)
F03D9/00C	Adaptations of wind motors for special use; Combinations of wind motors with apparatus driven thereby (aspects predominantly concerning driven apparatus)/ the apparatus being an electrical generator
H02J3/38	Circuit arrangements for ac mains or ac distribution networks/ Arrangements for parallely feeding a single network by two or more generators, converters or transformers
H02K17/42	DYNAMO-ELECTRIC MACHINES/ Asynchronous induction motors; Asynchronous induction generators/ Asynchronous induction generators
H02P9/00	CONTROL OR REGULATION OF ELECTRIC MOTORS, GENERATORS, OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS / Arrangements for controlling electric generators for the purpose of obtaining a desired output

US Classes

US Class	Definition
290/044	PRIME-MOVER DYNAMO PLANTS/ ELECTRIC CONTROL/ Fluid-current motors / Wind
290/055	PRIME-MOVER DYNAMO PLANTS/ FLUID-CURRENT MOTORS/ Wind
318/727	ELECTRICITY: MOTIVE POWER SYSTEMS/ INDUCTION MOTOR SYSTEMS
322/047	ELECTRICITY: SINGLE GENERATOR SYSTEMS/ GENERATOR CONTROL/ Induction generator

Concept Table

S.No	Concept1	Concept1	Concept1
1	Doubly fed	Induction	Generator
2	Double output	Asynchronous	Machines
3	Dual fed		Systems
4	Dual feed
5	Dual output

Search Strategy

The databases covered in the search include: US Grant, GB App, US App, FR App, WO App, DE Util, EP Grant, DE Grant, EP App, DE App, JP Util, JP Grant, JP App, CN Util, CN App, KR Util , KR Grant, KR App, Other, DWPI

S.No	No. of Hits	Remarks	Search String
1	795 hits	Doubly fed induction generator keywords	CTB=(((((Doubl3 or dual3 or two) adj3 (power2 or output4 or control4 or fed or feed3)) near5 (induction or asynchronous)) near5 (generat3 or machine1 or dynamo*1)) OR DFIG);
2	93 hits	Induction motor classes AND Doubly fed generator keywords	(UC=(318/727 OR 322/047) OR AIOE=(H02K001742)) AND ALL=(((((Doubl3 or dual3 or two) adj3 (power2 or output1 or control4 or fed or feed3)) near5 (generat3 or machine1 or dynamo*1))) OR DFIG);
3	675 hits	Broad classes of generators AND Doubly fed induction generator keywords	(UC=(290/044 OR 290/055) OR AIOE=(F03D000900C OR H02J000338 OR F03D0009* OR H02P0009)) AND ALL=(((((Doubl2 or dual3 or two) adj3 (power2 or output1 or control3 or fed or feed3)) near5 (induction or asynchronous)) near5 (generat3 or machine1 or dynamo1)) or DFIG);
4	240 hits	French keywords	CTB=((((Doubl3 or dual3or ADJ two or deux) near4 (nourris or feed3 or puissance or sortie1 or contrôle1)) near4 (induction or asynchrone1) near4 (générateur1 or generator1 or machine1 or dynamo1)) or DFIG);
5	282 hits	German keywords	CTB=(((((doppel1 or dual or two or zwei) adj3 (Ausgang or Ausgänge or Kontroll or control4 or gesteuert or Macht or feed1 or gefüttert or gespeiste1)) or (doppeltgefüttert or DOPPELTGESPEISTE1)) near4 (((Induktion or asynchronen) near4 (generator2 or Maschine1 or dynamo*1)) or (INDUKTION?MASCHINEN or INDUKTION?generatoren or Asynchronmaschine or Asynchrongenerator))) or DFIG);
6	920 hits		ALL=(((((((Doubl3 or dual3) adj3 (power2 or output4 or control4 or fed or feed3))) near5 (generat3 or machine1 or dynamo*1))) same wind) or (DFIG same wind)) AND DP>=(18360101);
7	1434 hits (702 INPADOC Families)	Combined Query	1 OR 2 OR 3 OR 4 OR 5 OR 6

Taxonomy

Sample Analysis

A sample of 139 patents from the search are analysed based on the taxonomy. Provided a link below for sample spread sheet analysis for doubly-fed induction generators.

Patent Analysis

S. No	Patent / Publication No.	Publication Year	Assignee / Applicant	Title	Doclera Analysis
S. No	Patent / Publication No.	Publication Year	Assignee / Applicant	Title	Problem	Solution
1	US20100045040A1	2010	Vestas Wind Systems	Variable speed wind turbine with doubly-fed induction generator compensated for varying rotor speed	The DFIG system has poor damping of oscillations within the flux dynamics due to cross coupling between active and reactive currents, which makes the system potentially unstable under certain circumstances and complicates the work of the rotor current controller. These oscillations ca damage the drive train mechanisms.	A comprensation block is arranged, which feeds a compensation control output to the rotor of the generator. The computation unit computes the control output during operation of the turbine to compensate partly for dependencies on a rotor angular speed of locations of poles of a generator transfer function, so that the transfer function is made independent of variations in the speed during operation of the turbine which eliminates the osicllations and increases the efficinecy of the wind turbine.
2	US20090267572A1	2009	Woodward SEG GMBH	Current limitation for a double-fed asynchronous machine	Abnormal currents can damage the widings in the doubly- fed induction gnerator. Cntrolling these currents with the subordinate current controllers cannot be an efficient way to extract the maximum amount of active power.	The method involves delivering or receiving of a maximum permissible reference value of an active power during an operation of a double-fed asynchronous machine, where predetermined active power and reactive power reference values are limited to a calculated maximum permissible active and reactive power reference values, and hence ensures reliable regulated effect and reactive power without affecting the power adjustment, the rotor is electrically connected to a pulse-controlled inverter by slip rings with a static frequency changer, and thus a tension with variable amplitude and frequency is imposed in the rotor.
3	US20090008944A1	2009	Universidad Publica De Navarra	Method and system of control of the converter of an electricity generation facility connected to an electricity network in the presence of voltage sags in said network	Double-fed asynchronous generators are very sensitive to the faults that may arise in the electricity network, such as voltage sags. During the sag conditions the current which appears in said converter may reach very high values, and may even destroy it.	During the event of a voltage sag occurring, the converter imposes a new setpoint current which is the result of adding to the previous setpoint current a new term, called demagnetizing current, It is is proportional to a value of free flow of a generator stator. A difference between a value of a magnetic flow in the stator of the generator and a value of a stator flow associated to a direct component of a stator voltage is estimated. A value of a preset calculated difference is multiplied by a factor for producing the demagnetizing current.
4	US7355295B2	2008	Ingeteam Energy, S.A.	Variable speed wind turbine having an exciter machine and a power converter not connected to the grid	a) The active switching of the semiconductors of the grid side converter injects undesirable high frequency harmonics to the grid.b) The use of power electronic converters (4) connected to the grid (9) causes harmonic distortion of the network voltage.	Providing the way that power is only delivered to the grid through the stator of the doubly fed induction generator, avoiding undesired harmonic distortion. Grid Flux Orientation (GFO) is used to accurately control the power injected to the grid. An advantage of this control system is that it does not depend on machine parameters, which may vary significantly, and theoretical machine models, avoiding the use of additional adjusting loops and achieving a better power quality fed into the utility grid.
5	US20080203978A1	2008	Semikron	Frequency converter for a double-fed asynchronous generator with variable power output and method for its operation	Optislip circuit with a resistor is used when speed is above synchronous speed, results in heating the resistor and thus the generator leads to limitation of operation in supersynchronous range which results tower fluctions.	Providing a back-to-back converter whic contains the inverter circuit has direct current (DC) inputs , DC outputs, and a rotor-rectifier connected to a rotor of a dual feed asynchronous generator. A mains inverter is connected to a power grid, and an intermediate circuit connects one of the DC inputs with the DC outputs. The intermediate circuit has a semiconductor switch between the DC outputs, an intermediate circuit condenser between the DC inputs, and a diode provided between the semiconductor switch and the condenser. Thus the sysem is allowed for any speed of wind and reduces the tower fluctuations.
6	US20070210651A1	2007	Hitachi, Ltd.	Power converter for doubly-fed power generator system	During the ground faults, excess currents is induced in the secondary windings and flows into power converter connected o secondar side and may danage the power converter. Conventional methos of incresing the capacity of the power cnverter increases system cost , degrade the system and takes time to activate the system to supply power again.	The generator provided with a excitation power converter connected to secondary windings of a doubly-fed generator via impedance e.g. reactor, and a diode rectifier connected in parallel to the second windings of the doubly-fed generator via another impedance. A direct current link of the rectifier is connected in parallel to a DC link of the converter. A controller outputs an on-command to a power semiconductor switching element of the converter if a value of current flowing in the power semiconductor switching element is a predetermined value or larger.
7	US20070132248A1	2007	General Electric	System and method of operating double fed induction generators	Wind turbines with double fed induction generators are sensitive to grid faults.Conventional methods are not effective to reduce the shaft stress during grid faults and slow response and using dynamic vltage restoreer (DVR) is cost expensive.	The protection system has controlled impedance devices.Impedance device has bidirectional semiconductors such triac, assembly of thyristors or anti-parallel thyristors. Each of the controlled impedance devices is coupled between a respective phase of a stator winding of a double fed induction generator and a respective phase of a grid side converter. The protection system also includes a controller configured for coupling and decoupling impedance in one or more of the controlled impedance devices in response to changes in utility grid voltage and a utility grid current. High impedance is offered to the grid during network faults to isolate the dual fed wind turbine generator.
8	US20060192390A1	2006	Gamesa Innovation	Control and protection of a doubly-fed induction generator system	A short-circuit in the grid causes the generator to feed high stator-currents into the short-circuit and the rotor-currents increase very rapidly which cause damage to the power-electronic components of the converter connecting the rotor windings with the rotor-inverter.	The converter is provided with a clamping unit which is triggered from a non-operation state to an operation state, during detection of over-current in the rotor windings. The clamping unit comprises passive voltage-dependent resistor element for providing a clamping voltage over the rotor windings when the clamping unit is triggered.
9	US20050189896A1	2005	ABB Research LTD	Method for controlling doubly-fed machine	Controlling the double fed machines on the basis of inveter control to implement the targets set for the machine, this model is extremely complicated and includes numerous parameters that are often to be determined.	A method is provided to use a standard scalar-controlled frequency converter for machine control. A frequency reference for the inverter with a control circuit, and reactive power reference are set for the machine. An rotor current compensation reference is set based on reactive power reference and reactive power. A scalar-controlled inverter is controlled for producing voltage for the rotor of the machine, based on the set frequency reference and rotor current compensation reference.

Click on the link below to view detailed analysis sheet for Doubly-Fed Induction Generator Patent Literature

Sample analysis on Doubly-Fed Induction Generator-Patent Literature

Article Analysis

S No.	Title	Publication Year	Journal / Conference	Dolcera Summary
1	Study on the Control of DFIG andIts Responses to Grid Disturbances	2006-Jan-01	Power Engineering Society General Meeting, 2006. IEEE	Presented dynamic model of the DFIG, including mechanical model, generator model, and PWM voltage source coverters. Vector control strategies adapted for both the RSC and GSC to control speed and reactive power independently. controlling desigining methods, such as pole-placement method and the internal model control are used. Matlab/Simulink is used for simulation.
2	Application of Matrix Converter for Variable Speed Wind Turbine Driving an Doubly Fed Induction Generator	2006-May-23	Power Electronics, Electrical Drives, Automation and Motion, 2006. SPEEDAM 2006.	A matrix converter is replaced with back to back converter in a variable speed wind turbine using doubly fed induction generator. Stable operation is achieved by stator flux oriented control techinque and the sytem opertaed in both sub and super synchronous modes, achieved good results.
3	Optimal Power Control Strategy of Maximizing Wind Energy Tracking and Conversion for VSCF Doubly Fed Induction Generator System	2006-Aug-14	Power Electronics and Motion Control Conference, 2006. IPEMC 2006. CES/IEEE 5th International	Proposed a new optimal control strategy of maximum wind power extraction stratagies and testified by simulation. The control algorithm also used to minimize the losses in the generator. The dual passage excitation control strategy is applied to decouple the active and reactive powers. With this control system, the simulation results shows the good robustness and high generator efficiency is achieved.
4	A Torque Tracking Control algorithm for Doubly–fed Induction Generator	2008-Jan-01	Journal of ELECTRICAL ENGINEERING	Proposed a torque tracking control algorithm for Doubly fed induction generator using PI controllers. It is achieved by controlling the rotor currents and using a stator voltage vector reference frame.
5	Fault Ride Through Capability Improvement Of Wind Farms Using Doubly Fed Induciton Generator	2008-Sep-04	Universities Power Engineering Conference, 2008. UPEC 2008. 43rd International	An active diode bridge crowbar switch presented to improve fault ride through capability of DIFG. Showed different parameters related to crowbar such a crowbar resistance, power loss, temparature and time delay for deactivation during fault.

Click on the link below to view detailed analysis sheet for Doubly-Fed Induction Generator-Non Patent Literature

Sample analysis on Doubly-Fed Induction Generator-Non Patent Literature

IP Trend Analysis

Patenting activity has seen high growth rate in the last two years.

Vestas Wind Systems and General Electric are the major players in this technology field.

Dashboard

Dashboard Link
Dashboard for doubly fed induction generator

Flash Player is essential to view the Dashboard

Market Research

Major Players

Vestas Wind Systems, General Electric and Gamesa Innovation & Technology are the top players in terms of installed power capacity in the year 2007.

S.No	Company	Installed Capacity
1	Vestas (Denmark)	4,500 MW
2	GE Energy (United States)	3,300 MW
3	Gamesa (Spain)	3,050 MW
4	Enercon (Germany)	2,700 MW
5	Suzlon (India)	2,000 MW
6	Siemens (Denmark / Germany)	1,400 MW
7	Acciona (Spain)	870 MW
8	Goldwind (China - PRC)	830 MW
9	Nordex (Germany)	670 MW
10	Sinovel (China - PRC)	670 MW

Source:Wind power companies

Market Overview

The world's wind industry defied the economic downturn in 2008 and by he end of the year 2009, the sector saw its annual market grow by 41.5% over 2008, and total global wind power capacity increased by 31.7% to 158GW in 2009
US, China and Germany together hold more than 50% of the global wind power capacity
Asia and North America have seen tremendous growth in the installed wind power capacity over the last 6 years
Asia was the world's largest regional market for wind energy with capacity additions amounting to 15.4GW. China was the world's largest market in 2009, more than doubling its capacity from 12.1GW in 2008 to 25.8GW, adding a staggering 13.8GW of capacity
China and the US account for more than 60% of the new installed capacity of 38.3GW in 2009. India's total installed capacity increased to 10.9GW with 1.3GW of new installed capacity in 2009
The 2009 market for turbine installations was worth about 45 bn € or 63 bn US$ and about half a million people are now employed by the wind industry around the world

Top 10 Cumulative Installed Capacity 2009

Top 10 New Installed Capacity 2009

Annual Installed Capacity by Region 2003-2009

Market Forecast

Global wind power capacity could reach 2,300 GW by 2030, providing up to 22% of the world's electricity needs, from the existing 2.2% in 2010.
Global wind capacity will stand at 409GW up from 158GW at the end of 2008. During 2014, 62.5 GW of new capacity will be added to the global total, compared to 38.3 GW in 2009
The annual growth rates during this period will average 20.9% in terms of total installed capacity, and 10.3% for annual market growth
Three regions will continue to drive the expansion of wind energy capacity: Asia, North America and Europe
Asia will remain the fastest growing market in the world, driven primarily by China, which is set to continue the rapid upscaling of its wind capacity and hold its position as the world’s largest annual market. Annual additions are expected to be well over 20 GW in China by 2014
Sustained growth is also expected in India, which will increase its capacity steadily by 2 GW every year, and be

complemented by growth in other Asian markets, including Japan, Taiwan, South Korea and the Philippines, and potentially some others

By 2014, the annual market will reach 14.5 GW, and a total of 60 GW will be installed in Europe over this five year period

ANNUAL MARKET FORECAST BY REGION 2009-2013

Source:GWEC's Global Wind Report 2009

Like this report?

This is only a sample report with brief analysis
Dolcera can provide a comprehensive report customized to your needs

Buy the customized report from Dolcera
Patent Analytics Services	Market Research Services	Purchase Patent Dashboard
Patent Landscape Services	Dolcera Processes	Industry Focus
Patent Search Services	Patent Alerting Services	Dolcera Tools

Contact Dolcera

Samir Raiyani
Email: info@dolcera.com
Phone: +1-650-269-7952

@@ Line 578: / Line 578: @@
 ===Patent Analysis===
 {| border="2" cellspacing="0" cellpadding="5" width="100%"
-| style="background-color:#ccffff"| <center>'''S. No'''</center>
+| rowspan="2" style="background-color:#ccffff"| <center>'''S. No'''</center>
-| style="background-color:#ccffff"| <center>'''Patent / Publication No.'''</center>
+| rowspan="2" style="background-color:#ccffff"| <center>'''Patent / Publication No.'''</center>
-| style="background-color:#ccffff"| <center>'''Publication Year'''</center>
+| rowspan="2" style="background-color:#ccffff"| <center>'''Publication Year'''</center>
-| style="background-color:#ccffff"| <center>'''Assignee / Applicant'''</center>
+| rowspan="2" style="background-color:#ccffff"| <center>'''Assignee / Applicant'''</center>
-| style="background-color:#ccffff"| <center>'''Title'''</center>
+| rowspan="2" style="background-color:#ccffff"| <center>'''Title'''</center>
 | colspan="2"  style="background-color:#ccffff"| <center>'''Doclera Analysis'''</center>
 |-
-||
-|
-|
-|
-|
-|
-|
-|
-|
 | style="background-color:#ccffff"| <center>'''Problem'''</center>
 | style="background-color:#ccffff"| <center>'''Solution'''</center>
 |-
-| style="background-color:#ccffff"| <center>3</center>
+| style="background-color:#ccffff"| <center>1</center>
 | <center>[http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220100045040%22.PGNR.&OS=DN/20100045040&RS=DN/20100045040 US20100045040A1]</center>
 | <center>2010</center>
@@ Line 606: / Line 597: @@
 |-
-| style="background-color:#ccffff"| <center>4</center>
+| style="background-color:#ccffff"| <center>2</center>
 | <center>[http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220090267572%22.PGNR.&OS=DN/20090267572&RS=DN/20090267572 US20090267572A1]</center>
 | <center>2009</center>
@@ Line 615: / Line 606: @@
 |-
-| style="background-color:#ccffff"| <center>5</center>
+| style="background-color:#ccffff"| <center>3</center>
 | <center>[http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220090008944%22.PGNR.&OS=DN/20090008944&RS=DN/20090008944 US20090008944A1]</center>
 | <center>2009</center>
@@ Line 624: / Line 615: @@
 |-
-| style="background-color:#ccffff"| <center>6</center>
+| style="background-color:#ccffff"| <center>4</center>
 | <center>[http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=7355295.PN.&OS=PN/7355295&RS=PN/7355295 US7355295B2]</center>
 | <center>2008</center>
@@ Line 633: / Line 624: @@
 |-
-| style="background-color:#ccffff"| <center>7</center>
+| style="background-color:#ccffff"| <center>5</center>
 | <center>[http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220080203978%22.PGNR.&OS=DN/20080203978&RS=DN/20080203978 US20080203978A1]</center>
 | <center>2008</center>
@@ Line 642: / Line 633: @@
 |-
-| style="background-color:#ccffff"| <center>8</center>
+| style="background-color:#ccffff"| <center>6</center>
 | <center>[http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220070210651%22.PGNR.&OS=DN/20070210651&RS=DN/20070210651 US20070210651A1]</center>
 | <center>2007</center>
@@ Line 651: / Line 642: @@
 |-
-| style="background-color:#ccffff"| <center>9</center>
+| style="background-color:#ccffff"| <center>7</center>
 | <center>[http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220070132248%22.PGNR.&OS=DN/20070132248&RS=DN/20070132248 US20070132248A1]</center>
 | <center>2007</center>
@@ Line 660: / Line 651: @@
 |-
-| style="background-color:#ccffff"| <center>10</center>
+| style="background-color:#ccffff"| <center>8</center>
 | <center>[http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220060192390%22.PGNR.&OS=DN/20060192390&RS=DN/20060192390 US20060192390A1]</center>
 | <center>2006</center>
@@ Line 669: / Line 660: @@
 |-
-| style="background-color:#ccffff"| <center>11</center>
+| style="background-color:#ccffff"| <center>9</center>
 | <center>[http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220050189896%22.PGNR.&OS=DN/20050189896&RS=DN/20050189896 US20050189896A1]</center>
 | <center>2005</center>
@@ Line 678: / Line 669: @@
 |}
 Click on the link below to view detailed analysis sheet for Doubly-Fed Induction Generator Patent Literature
 * [[Media:Doublyfed_induction_generator1.xls| Sample analysis on Doubly-Fed Induction Generator-Patent Literature]]<br>

Difference between revisions of "Wind Energy"

Revision as of 01:02, 28 February 2011

Contents

Introduction

Brief History of Wind Energy

Working Principle of Wind Turbine

Horizontal Axis and Vertical Axis Wind Turbines

Horizontal Axis Wind Turbines

Onshore and Offshore Wind Turbines

Parts of a Horizontal Axis Wind Turbine

Tower

Blades

Nacelle

Anemometers

Yaw Mechanism

Electrical Generating Systems

Wind Turbine Control Systems

Taxonomy for Wind Turbines

Major IPC classes

Major Players

Like this report?

Doubly-fed Induction Generator

Control patents

Thomson Innovation Search

IPC/ ECLA Classes

US Classes

Concept Table

Search Strategy

Taxonomy

Sample Analysis

Patent Analysis

Article Analysis

IP Trend Analysis

Dashboard

Market Research

Major Players

Market Overview

Market Forecast

Like this report?

Contact Dolcera

Navigation menu

Search