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318 bytes added, 03:33, 16 March 2011
/* Patent Analysis */
Provided a link below for sample spread sheet analysis for doubly-fed induction generators.<br>
===Patent Analysis===
{| border="2" cellspacing="0" cellpadding="54" width="100%"| align = "center" bgcolor = "#4F81BD" rowspan="2" stylewidth="background-color:#99ccff38"| <centerfont color="#FFFFFF">'''S. No'''</centerfont>| rowspanalign ="2center" stylebgcolor ="background-color:#99ccff4F81BD" rowspan = "2"| <centerfont color="#FFFFFF">'''Patent / Publication No.'''</centerfont>| align = "center" bgcolor = "#4F81BD" rowspan="2" stylewidth="background-color:#99ccff105"| <centerfont color="#FFFFFF">'''Publication YearDate<br>'''(mm/dd/yyyy)</centerfont>| rowspanalign ="2center" stylebgcolor ="background-color:#99ccff4F81BD" rowspan = "2"| <centerfont color="#FFFFFF">'''Assignee / Applicant'''</centerfont>| rowspanalign ="2center" stylebgcolor ="background-color:#99ccff4F81BD" rowspan = "2"| <centerfont color="#FFFFFF">'''Title'''</centerfont>| colspanalign ="2center" stylebgcolor ="background-color:#99ccff4F81BD" colspan = "2"| <centerfont color="#FFFFFF">'''Doclera Dolcera Analysis'''</centerfont
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| stylealign = "center" bgcolor ="background-color:#99ccff95B3D7"| <center>'''Problem'''</center>| stylealign = "center" bgcolor ="background-color:#99ccff95B3D7"| <center>'''Solution'''</center> 
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| stylealign = "center" bgcolor ="background-color:#99ccffDCE6F1"| <center>'''1'''</center>|bgcolor = "#DCE6F1"| <centerfont color="#0000FF"><u>[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=%2220100117605%22.PGNR.&OS=DN/20100117605&RS=DN/20100117605 US20100117605A1US20100117605]</centeru>| <center>2010</centerfont>| <align = "center>Woodward Seg Gmbh <" bgcolor = "#DCE6F1"|05/center>13/10|bgcolor = "#DCE6F1"|Woodward|bgcolor = "#DCE6F1"| Method of and apparatus for operating a double-fed asynchronous machine in the event of transient mains voltage changes|bgcolor = "#DCE6F1"| The short-circuit-like currents in the case of transient mains voltage changes lead to a corresponding air gap torque which loads the drive train and transmission lines can damages or reduces the drive train and power system equipments.|bgcolor = "#DCE6F1"| The method presents that the stator connecting with the network and the rotor with a converter. The converter is formed to set a reference value of an electrical amplitude in the rotor, by which a reference value of the electrical amplitude is setted in the rotor after attaining a transient mains voltage change, such that the rotor flux approaches the stator flux.  
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| stylealign ="background-color:#99ccffcenter"| <center>'''2'''</center>| <centerfont color="#0000FF"><u>[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 US20100045040A1US20100045040]</centeru></font>| <align = "center>2010<"|02/center>25/10| <center>Vestas Wind Systems</center>| 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. 
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| stylealign = "center" bgcolor ="background-color:#99ccffDCE6F1"| <center>'''3'''</center>|bgcolor = "#DCE6F1"| <centerfont color="#0000FF"><u>[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 US20090267572A1US20090267572]</centeru>| <center>2009</centerfont>| <align = "center>Woodward Seg Gmbh <" bgcolor = "#DCE6F1"|10/center>29/09|bgcolor = "#DCE6F1"|Woodward|bgcolor = "#DCE6F1"| Current limitation for a double-fed asynchronous machine|bgcolor = "#DCE6F1"| 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.|bgcolor = "#DCE6F1"| 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. 
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| stylealign ="background-color:#99ccffcenter"| <center>'''4'''</center>| <centerfont color="#0000FF"><u>[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 US20090008944A1US20090008944]</centeru></font>| stylealign ="background-color:#ffffffcenter"| <center>2009<01/center>08/09| <center>Universidad Publica De Navarra</center>| 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. 
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| stylealign = "center" bgcolor ="background-color:#99ccffDCE6F1"| <center>'''5'''</center>|bgcolor = "#DCE6F1"| <centerfont color="#0000FF"><u>[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 US7355295B2US7355295]</center>| <centeru>2008</centerfont>| <align = "center>" bgcolor = "#DCE6F1"|04/08/08|bgcolor = "#DCE6F1"|Ingeteam Energy</center>|bgcolor = "#DCE6F1"| Variable speed wind turbine having an exciter machine and a power converter not connected to the grid|bgcolor = "#DCE6F1"| a) The active switching of the semiconductors of the grid side converter injects undesirable high frequency harmonics to the grid.<br>b) The use of power electronic converters (4) connected to the grid (9) causes harmonic distortion of the network voltage.|bgcolor = "#DCE6F1"| Providing the way that power is only delivered to the grid through the stator of the doubly fed induction generator, avoiding undesired harmonic distortion. <br>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. 
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| stylealign ="background-color:#99ccffcenter"| <center>'''6'''</center>| <centerfont color="#0000FF"><u>[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 US20080203978A1US20080203978]</centeru>| <center>2008</centerfont>| <align = "center>"|08/28/08|Semikron</center>| 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. 
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| stylealign = "center" bgcolor ="background-color:#99ccffDCE6F1"| <center>'''7'''</center>|bgcolor = "#DCE6F1"| <centerfont color="#0000FF"><u>[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 US20070210651A1US20070210651]</centeru>| <center>2007</centerfont>| <align = "center>Hitachi Ltd<" bgcolor = "#DCE6F1"|09/center>13/07|bgcolor = "#DCE6F1"|Hitachi|bgcolor = "#DCE6F1"| Power converter for doubly-fed power generator system|bgcolor = "#DCE6F1"| 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.|bgcolor = "#DCE6F1"| 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. 
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| stylealign ="background-color:#99ccffcenter"| <center>'''8'''</center>| <centerfont color="#0000FF"><u>[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 US20070132248A1US20070132248]</centeru></font>| <align = "center>2007<"|06/center>14/07| <center>General Electric Company</center>| 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. 
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| stylealign = "center" bgcolor ="background-color:#99ccffDCE6F1"| <center>'''9'''</center>|bgcolor = "#DCE6F1"| <centerfont color="#0000FF"><u>[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 US20060192390A1US20060192390]</centeru>| <center>2006</centerfont>| <align = "center>" bgcolor = "#DCE6F1"|08/31/06|bgcolor = "#DCE6F1"|Gamesa Innovation</center>|bgcolor = "#DCE6F1"| Control and protection of a doubly-fed induction generator system|bgcolor = "#DCE6F1"| 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.|bgcolor = "#DCE6F1"| 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. |-|align = "center"|10|<font color="#0000FF"><u>[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 US20050189896]</u></font>|align = "center"|09/01/05|ABB Research|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.
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| style="background-color:#99ccff"| <center>'''10'''</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>| <center>ABB Research Ltd</center>| 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.
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Click on the link below to view detailed analysis sheet for Doubly-Fed Induction Generator Patent Literature
685
edits