MXPA00001375A

MXPA00001375A - Variable speed wind turbine generator

Info

Publication number: MXPA00001375A
Application number: MXPA/A/2000/001375A
Authority: MX
Inventors: Amir S Mikhail; Craig L Christenson; Kevin L Cousineau; William L Erdman; E Holley William
Original assignee: Zond Energy Systems Inc
Priority date: 1997-08-08
Filing date: 2000-02-08
Publication date: 2001-03-05

Abstract

A variable speed system for use in systems, such as, for example, wind turbines, is described. The system comprises a wound rotor induction generator (620), a torque controller (623) and a proportional, integral derivative (PID) pitch controller (1010). The torque controller controls generator torque using field oriented control, and the PID controller performs pitch regulation based on generator rotor speed.

Description

VARIABLE SPEED EOLIC TURBINE GENERATOR FIELD OF THE INVENTION The present invention relates to the field of wind turbines, more particularly the present invention relates to variable speed wind turbines having a double feed generator and applying torque control of torsion and pitch regulation based on generator rotor speed. BACKGROUND OF THE INVENTION Recently, wind turbines have received increased attention as alternate environmental sources that are safe and relatively inexpensive. With this growing interest, considerable efforts have been made to develop wind turbines that are reliable and efficient. In general, a wind turbine includes a rotor that has multiple blades. The rotor is mounted inside a housing that is placed on a tubular tower or armor. The blades of the turbine transform the energy of the wind into a torque or rotational force that displaces one or more generators, rotationally coupled to the rotor through a gearbox. The gearbox multiplies the inherently low rotational speed of the turbine rotor, so that the generator efficiently converts mechanical energy into electrical energy, which is fed into an energy distribution network. Many types of generators have been used in wind turbines. At least one wind turbine of the prior art has included a winding rotor generator with double feed. See the patent of the U.S.A. No. 4,994,684 titled "Doubly Fast Generator Variable Speed Generation Control System" (Variable Speed Generation Control System with Double Feed Generator) issued on February 19, 1991. A generator with rotor induction winding (RIG = Wound Rotor Induction Generator) typically includes four main parts: the stator, the rotor, slip rings and the end caps with bearings. A cross-sectional view of a three-phase, two-pole generator is illustrated in Figure 1, where for simplicity, the windings are illustrated as a pair of conductors. With reference to Figure 1, the generator 100 comprises the stator 101, rotor 102 and winding of phase A for each of the rotor and stator, 103 and 104, respectively. An arrow 105 which couples the blades of the wind turbine through the gearbox to the generator 100, is also shown. With reference to Figure 2, in a WRIG system, the stator winding 104 is typically connected to a power network with three-phase service, such as the three-phase network of 480 V 201, and the rotor winding 103 is connects an inverter on generator side 202 by slip rings (not shown). The winding 104 is also coupled to the three-phase source of 480 V, 201, in parallel with a line-side inverter 203. The line-side inverter 203 and the generator-side inverter 202 are coupled together by a CD conduit 204. The configuration shown in Figure 2 (ie the line-side inverter 203, conduit CD 204 and generator-side inverter 202) allows power to flow in or out of the rotor windings 103. Both inverters they are under the control of a digital signal processor (DSP = Digital Signal Processor) 205. Some conventional wind or wind turbines rotate at a constant speed to produce electricity at a constant frequency, for example 60 cycles per second (60 Hz) which is a standard of the U.S.A. for alternating current or 50 Hz which is a European standard. Because the wind speeds change continuously, these turbines use an active aerodynamic control (step regulation) or passive control (regulation of flow detachment) in combination with the characteristics of two conventional squirrel-cage induction generators to maintain a speed of constant turbine rotor. Some turbines operate at variable speed when using a power converter to adjust their output. As the turbine speed fluctuates, the frequency of the alternating current that circulates from the generator also varies. The power converter, placed between the generator and the grid, converts alternating current from variable frequency into direct current, and then converts it back to alternating current with constant frequency. The total power output of the generator is combined by the converter (total conversion). For an example of that turbine, see the US patent. No. 5,083,039 titled "Variable Speed Wind Turbine" (Variable Speed Wind Turbine) granted on January 21, 1992. The use of variable speed wind turbines to use electric power has many advantages that include superior efficiency of propeller than wind turbines of constant speed, control of reactive power VARs and power factor, and mitigate loads. Some variable speed wind turbines of the prior art are total conversion systems that use a power converter to completely rectify the entire power output of the wind turbine. That is, the wind turbine, which operates at a variable frequency, generates a variable frequency output and converts it into a fixed frequency to track the grid. These systems that use total conversion are very expensive. Due to the cost, the parties often look for lower cost solutions, such as for example a winding rotor generator system that utilizes partial conversion, where only a portion of the wind turbine output is rectified and inverted by the power converter. Some problems currently exist with various control algorithms used by power converters to control the partial conversion process. For example, certain systems have stability problems because they have large oscillations in power and torque. Other systems can not produce enough power without overheating critical components or are not refined so easily to provide an effective cost solution for mass production. In this way there is a need for a low cost wind turbine system that does not have the stability problems of the prior art, however it still produces a large amount of power, or of energy effective in cost, without generating excessive amounts of heat and it can be easily refined in an easily reproducible design, effective in cost. COMPENDIUM OF THE INVENTION A variable speed system is described for use in systems such as, for example, wind turbines. The system comprises an induction generator with coiled rotor, a torque controller and a step controller. The torque controller controls the generator torque using a field-oriented control approach. The step controller performs pitch regulation d on the rotor speed of the generator, which is independent of the torque controller. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be more fully understood from the detailed description given below and from the accompanying drawings of various embodiments of the invention which, however, should not be taken to limit the invention to the specific modalities but for explanation and understanding only. Figure 1 illustrates a cross-sectional view of an induction generator with simplified coiled rotor.

Figure 2 illustrates a typical system configuration incorporating an induction generator with coiled rotor. Figure 3 illustrates the relationship of equality between the torque and the cross product of current and flow. Figure 4 illustrates a coiled field CD motor. Figure 5 illustrates the direction of flow when only phase "A" is energized. Figure 6A is a flow diagram of one embodiment of the system of the present invention. Figure 6B is a block diagram of an embodiment of the coiled rotor and torsion control induction generator of the present invention. Figure 6C illustrates the relationship between the flow vector and the rotor current vector. Figure 6D illustrates components of the rotor current. Figure 7 is a flow diagram of one embodiment of the wind turbine controller of the present invention, illustrating the active / deactivated sequence for the torque / power controller in the different modes of the step controller.

Figure 8 is a flow chart of one mode of the pitch regulation mode of the present invention. Figure 9 is a flow diagram of one mode of the RPM regulation mode of the present invention. Figure 10A is a block diagram of a mode of a step control system. Figure 10B is a block diagram of an embodiment of the proportional, integral, derivative (PID = Proportional Integral Derivated) controller of the present invention. DETAILED DESCRIPTION OF THE PRESENT INVENTION A variable speed system is described. In the following description, numerous details are set such as set points, watt numbers, etc. It will be apparent however to a person skilled in the art that the present invention can be practiced without these specific details. In other cases, well-known structures and devices are illustrated in block diagram form, rather than in detail in order to avoid obscuring the present invention. Generalities of the Present Invention The present invention provides a variable speed system. In one embodiment, the variable speed system comprises a wind turbine generator with power capacity / torque, which is coupled to and supplies the power generated to a network. In one embodiment, the generator of the present invention comprises an induction generator with a coiled rotor (WRIG = Wound Rotor Induction Generator) or a double feed generator (DFG = Doubly Fed Generator) and a rotor that uses blade pitch regulation and operation of variable speed to achieve optimum power output at all wind speeds. The ability of an induction generator to generate power is equivalent to its ability to produce torque at rotational speeds. When a torque is exerted on the generator rotor in the opposite direction in its rotation, the mechanical energy of the rotor is converted to electrical energy. In an induction generator, the torque as derived from the interaction between the flow stream as illustrated in Figure 3, or more precisely, the torque in the cross product of current and flow. To obtain maximum torque for a given flow level, the direction of the rotor current vector is maintained exactly at 90 ° from the direction of flow. In a CD motor, this perpendicular relationship between armature flow and current is achieved by switches.

Figure 4 shows the mechanical structure of a coiled field CD motor. Due to the separate armature and the field windings, a CD motor can be controlled by regulating the armature current for a desired torque output and by regulating the field winding current for the desired flow rate. The generation of torque in an induction generator operates on the same principle as in a CD motor. The main difference between the two is that a CD motor, both the flow and the direction of armature current are fixed, while in an induction generator, these two vectors rotate constantly. Field-Oriented Control (FOC = Field Oriented Control) is an algorithm that identifies the flow vector and controls the production current of compliance torque. Figure 5 shows the direction of flow when only phase A of the stator winding is energized. In the system shown in Figure 2, the stator phases sequentially energize a three-phase voltage source and this creates a rotary flow vector. It should be noted that both the three-phase flow and current are two-dimensional (2D) vectors (ie with a magnitude and an angle) and with rotor current 0, the flow vector (?) Is related to the vector of Stator current (Is) by the following algebraic equation: (1)? = Ls * Is where Ls is the stator inductance. Without the rotor winding being energized, the generator behaves like an inductor, ie the stator current retards the stator voltage 90 ° or more precisely, (2) Vs = d? / Dt = Ls d Is / dt in where Vs represents the stator voltage. An important element in the FOC is the flow model. The flow model is used to identify the flow vector. Equation (1) is a very simple form of the flow model for a WIRG and indicates that the flow vector can be identified simply by taking the product of the stator current measurement (Is) and the stator inductance (Ls). By using the flow model, the flow vector can be identified in such a way that the torque can be controlled to generate power. Although the following discussion describes the present invention in terms of variable speed wind turbine, the present invention has application to other dielectric mechanical systems. For example, the generator of the present invention can be used in systems having other sources that rotate in an arrow coupled to the generator rotor, such as hydroelectric, gas turbine, and initial or general prime, etc. In one embodiment, the wind turbine of the present invention comprises the rotor that is of three blades and comprises blades with full pitch control, pitch bearings and a hub. This wind turbine rotor is well known in the art, it should be noted that any number of blades or any turbine configuration can be employed in the present invention. The wind turbine rotor is coupled to an integrated drive train that includes a main arrow. The main arrow is coupled to the generator. The system of the present invention also comprises a power converter in the excitation circuit between the grid or the network and the coiled rotor of the induction generator with double-wound coiled rotor. The stator is connected by a contactor to the network. Since the converter is in the rotor circuit, it processes (for example converts) a fraction of the total nominal kilowatt output (KW) of the turbine rotor. In one embodiment, the total nominal output of the turbine rotor comprises 750 KW, and the converter converts at most 25 to 30% of the total rated power (for example 160 KW). In one embodiment, the generator comprises an induction generator with a coiled rotor of 750 KW, 460 volts. In one embodiment, the present invention provides a variable speed system having an induction generator with coiled rotor, a torque controller, and a proportional, integral, derivative (PID) step controller (or speed). The induction generator of the present invention may comprise a friction or non-rubbing ring induction generator. The variable speed system uses the induction generator with winding rotor, with a power converter system to ensure the supply of power with constant frequency to the network. It should be noted that although network applications are described, it would be apparent to a person skilled in the art that the present invention can also be employed in other applications such as autonomous power systems. The torque controller, which is typically part of the power converter, controls the torque of the generator. In one embodiment, the torque controller controls the generator torque as a function of the generator speed with a field-oriented control approach (FOC = Field Oriented Control) using flow vector control. The torque controller operates in the generator from wind speeds of cut to nominal. In one embodiment the cut refers to the lowest wind speed at which the generator or turbine is designed to operate, while the nominal speed is the minimum wind speed at which the turbine produces its maximum power (for example 750 KW). In one embodiment, at wind speeds above the nominal, the torsion pax controller keeps the rotor of the generator at a constant power. In one embodiment, the power controller comprises a look-up table (LUT = Look Up Table) which outputs power values as a function of the generator rotor speeds. The power controller interpolates the LUT, which contains a coded speed-power curve to obtain a target output power. This power is then divided by the speed of the generator rotor measured to obtain a torque of the desired generator, from the equation T = P /? (torque = power / angular speed). In one embodiment, the output of the LUT is a target output power that is compared to the current output power, using physical equipment or software (software) comparator or differentiator, to generate a power error indication. A proportional, integral controller (Pl = Proportional, Integral) generates a current output power value adjusted in response to the power error indication, which when divided by the speed of the measured generator rotor, by hardware or software divider , results in a controlled torque. Torque-cutting torque causes a specified rotor current vector to be printed on the rotor, which interacts with an identified flow vector, to produce a desired generator torque. In this way, the present invention also allows to control the torque of the generator, by measuring the rotor speed of the current generator, access a LUT using the measured rotor speed to obtain a target output power, compare the current output power to the target output power and generate a controlled torque when adjusting a torque calculation to maintain a predetermined output based on the comparison of the current output power to the target output power. In one embodiment, a process is employed to synchronize this variable speed system which includes connecting a generator stator, connecting a generator rotor, advancing upstream an Ird rotor current magnetization current (torque producing component of the rotor current) and regulate the torque of the generator by controlling the flow-producing component of the rotor current Irq. The system of the present invention also includes a sub-system for speed regulation and variable pitch, which provides proportional pitch position in real time, as well as turbine speed regulation, when using a proportional, integral, derivative controller (PID). The PID controller performs pitch regulation based on the speed of the generator rotor and operates independently of the torque controller in the power converter. In one embodiment, the PID controller is a closed-loop PID controller that generates a step velocity to perform pitch regulation while at or above the nominal wind speeds. In one embodiment, the PID controller also begins to perform pitch regulation for less than nominal wind speeds. In one mode, below the rated speed, the pitch angle is set at the full energized position. The PID controller - controls the speed of the generator rotor when changing the pitch of the blades of a wind turbine. In one embodiment, the PID controller generates an output voltage in response to a difference between the target rotor speed and the measured (or current) rotor speed that a non-linear LUT (in one embodiment, table 1011 FIG. 10) uses for send out a step speed in response. Although the present invention is described in conjunction with a PID controller, a controller provides, integral (Pl) a proportional controller, derivative (PD) or a proportional controller can be used in modalities. Other late-start or retard-advance controllers can also be used. Also, although the present invention is described in conjunction with a closed loop controller, an open loop controller such as an open loop controller with a derivative term may be employed. These types of controllers are well known in the art. System Overview Figure 6A illustrates one embodiment of a system according to the present invention. With reference to Figure 6A, a generator torque control 603, is a variable speed drive, coupled to receive a calculated torque 601 based on the measured RPM 607 and a maximum torque set point. pre-selected 602. In one embodiment, the calculated torque 601 is a function of the measured RPM of the generator, based on the speed-power curve / look-up table 640. The output of the table 640 is divided by the measured RPM 607 using the divider 641. In one embodiment, the maximum torque 602 is adjusted to approximately 5250 Nm and its selection is based on the maximum available current of the thermal ratings of the converter system. In other words, the selection is based on a characteristic curve of torque velocity calculated for a particular turbine rotor design. In one embodiment, this selection is based on an excitation amount of 290 amps. In response to these feeds, the torque control 603 generates a torque command to control the generator rotor 604. The torque control 603 is also coupled to receive a VAR or a power factor command 642 The other generator 504 is coupled to receive the torque command from the generator torque control 603 and is coupled to provide power between a flow space at the output of the generator stator 605. A feedback 612 is coupled from the output of the generator stator 505 at the input of the generator rotor 604. The outputs of the generator rotor 604 and the generator stator 605 are coupled to the service network 606.

The generator rotor 604 is also coupled to a measuring device that produces a measured speed 607 (in rpm) of the generator rotor 604. In one embodiment, the measuring device comprises an optical encoder that provides position as well as rotational speed of the rotor of generator 604. A proportional, integral, derivative controller (PID) and a step speed limit block 609 are coupled to receive the measured speed 607 and an operating speed set point (rpm) 608. The operating speed set point can be regulated based on the same speed characteristic of torque used to set the maximum torque set point. In a modality, the operating speed set point is based on maximum torque and power. In one embodiment, the operating speed set point 608 is 1423 rpm. In response to these feeds, the step speed limit block and PID 609 generates a voltage output. A variable step control (VPC = Variable Pitch Control) 610 is coupled to receive the pitch velocity output of the PID and the step speed limit block 609. VPC 610 is coupled to the blade rotor 611 to regulate the speed of the generator rotor 604 by controlling the aerodynamic torque of the rotor. 611 blade rotor feeding through the blade pitch action. The step speed limit block and PID 609 generates a desired step velocity, which is converted to a voltage using a table, as described in more detail below. A variable voltage output is applied to a proportional value in a hydraulic system that changes the pitch of the blades when operating a step cylinder or variable speed. In this way, the variable step control regulates the rpm when controlling the aerodynamic torque. The step speed limit block and PID 609 including the rpm measures 607 and the operating speed set point (rpm) 608, VPC 610 and the blade rotor 611 form the blade passing system 650, while the measured rpm 607 and the remaining portion of the system in Figure 6A, are part of the generator system and power converter 651. It should be noted that in one embodiment, the measured rpm 607 is used simultaneously by the blade passing system 650 and the generating system / power converter 651. The power converter of the present invention. In the present invention, the power converter controls the induction generator with coiled rotor according to a predetermined power-speed curve. By following the predetermined speed-power curve, the variable speed system is capable of operating the turbine at the maximum power coefficient (Cp) of nominal cut-off wind speeds, which is referred to here as region II, thus ensuring that a maximum aerodynamic energy capture is achieved. It should be noted that the velocity-power curve is related to a velocity-torque curve since P = T ?. In one embodiment, the speed-power curve is encoded in the power converter in the form of a power search table (LUT) and corresponding generator speeds. The LUT may reside in physical equipment or software. To control the torque, the power converter measures the rotor speed of the generator, interpolates the LUT to determine the target turbine output power and calculates the torque of the desired generator from the ratio T = P /? , using the speed of the generator rotor. In one embodiment, this torque occurs when determining the current required vector and using well-known pulse width modulation techniques, produces this vector. In one embodiment, due to slight differences between the theoretical and the current, the power converter of the present invention employs a closed-loop controller Pl, which compares the current turbine power output with a target or desired output and makes small adjustments to the calculation of torque to achieve and maintain a desired turbine output. The torque controller of the power converter uses field-oriented control (FOC) to produce generator torque as a function of the rotor speed of the generator. Using the stator current, the rotor current and the rotor angle as feeds, the torque controller of the power converter identifies the flow vector and directs the required current vector of the rotor which, in interaction with the vector of the rotor. Stator flux, produces the desired generator torque. The rotor current is created by the proper switching of the isolated bi-polar gate transistors of the converter (IGBTs = Insulated Gate Bipolar Transistors) using well-known pulse width modulation (PWM = Pulse Wide Modulation) current regulation techniques. , as described in the US Patent No. 5, 083,039 titled "Variable Speed Wind Turbine" (Variable Speed Wind Turbine) granted on January 21, 1992. In this way, the power control system follows an aerodynamically optimized speed-torque / power profile. It should be noted that the values of the look-up table containing the velocity-torque / power profile are based on the aerodynamics of the wind turbine rotor and the geometry of the particular wind turbine rotor. Therefore, the values of the established table can vary for different turbine rotors. One embodiment of the torque controller and the relevant portions of the winding rotor induction generator are illustrated in Figure 6B. The torque can be expressed as (3) Td = k *? * Irq Where k is a generator parameter. From the point of view of the controller, equation (3) takes the following formula (4) Irq = Td / (k *?) Equation (4) gives the magnitude of the rotor current for a desired "torque" Td, which is output from a torque command controller 623. Referring to Figure 6B, the torque controller 623 comprises a power table 623A, controller Pl 623B, divider 623C, switch 629 and comparators. 623B and 623E, which can be implemented in physical equipment or software to generate difference values and a cushion filter with 623F anticipatory correction. The power table 623A is a LUT coupled to receive the speed of the generator 607 and outputs an objective power value corresponding to the speed of the generator 607. A power table mode 623A is illustrated in Table 1 below. Table 1 The target output power is compared by the comparator 623D, to generate a difference between the target output power and the current output power. The resulting difference is fed to the Pl 623B controller which adjusts the power as described herein. The divider 623C is coupled to receive the adjusted power from the Pl controller 623B and the speed of the generator 607 to output a controlled torque. The controlled torque can be adjusted by a value of torque generated by the dampening filter with anticipatory correction 623F. The damped filter 623F detects the oscillation movement (at resonance) of the non-rigid (yielding) arrow (not shown to avoid blocking the invention) caused by its coupling between two separate inertias, one due to the gearbox and generator and the other due to the blades of the turbine. In response to this detection, the cushion filter 623F applies a negative torque to reduce the relative movement between the two inertias. In one embodiment, the cushion filter 623F comprises a bandpass filter wherein the passband is centered on the resonant frequency of the two inertias and the arrow. The resulting controlled torque is printed on the coiled rotor of the induction generator. The switch 629 operates in response to a braking indication (e.g., signal (s)) to switch the controlled torque to a maximum constant torque 660 as described in more detail below. For torque production operation, a rotor current component Irq is controlled to follow the perpendicular direction of the flow (see Figure (6D)). The magnitude of Irq is given by the following equation Irq = Td / (k *?) Where k is a generator parameter. It should be noted that the rotor current, Ird, which is discussed in more detail below, creates the flow of the generator and does not contribute to the production of torque. The current component block of the rotor 623 is coupled to receive the controlled torque and the scalar component of the flow vector from the rectangular-to-polar coordinate transformation block 626, which converts the flow vector of the flow 621 to the polar coordinates. In response to these feeds, the rotor current component block 622 generates the rotor current torque component, Irq. Flow model 621 identifies the flow vector. To identify the flow vector, the current converting blocks 621A and 621B obtain the stator current vector and the rotor current vector. It should be noted that since the current vector can be determined from the measurement of two of the three phase currents, only two current detectors (not shown) are required. The stator current vector with the rotor angle 62IB of the generator 620 is fed to the frame transformation block 627C. The 627C frame transformation block transforms the stator current to a fixed rotor frame. From the outputs of the frame transformation block 6210., the stator inductance Ls is determined in block 62ID. From the rotor current vector, rotor inductance Lr can be obtained in block 621F. The flow vector is generated from the inductance of the stator Ls and the inductance of the rotor Lr. Once the flow vector is determined, the output of the rotor current vector from the inverter 624 is "located" in the perpendicular direction of the flow to produce torque. Since the rotor current is specified with respect to the rotor structure, the rotor current command depends against the flow angle as the rotor angle. Specifically, the flow angle first becomes a fixed reference frame of the rotor and in this reference frame, the direction of the rotor current command is the direction perpendicular to the direction of flow. This procedure is shown in Figure 6C.

Using the rotor current component, Irq, in conjunction with the inductive portion of the output of the transformation block 626, a current reference is generated in the power supply of the inverter 624. The inverter 630 coupled to the inverter 624 is also illustrated by the duct CD 631 and coupled to the stator side (line side) of the generator 620. When this rotor current is forced to circulate through the rotor windings, the desired torque Td develops and the power (Td *? ) is generated, where? is the speed of the rotor. This energy is generated in the form of stator current that flows back to the network. This stator current that "carries power" is in phase with the stator voltage. When the power is produced by the generator, the flow model described in equation (1) above is no longer valid, since the stator current (Ls) now consists of two components: component that produces flow and component that transports power. This component that carries power does not contribute to the production of flow because this current component has the same magnitude (after normalizing by the transformation ratio) as the rotor current that produces torque but in the opposite direction. In other words, the flux produced by these two current vectors (ie, stator current carrying power and rotor current that produces torque) added together as a whole. To remove the component that carries power from the current measurement of the stator, the rotor current (Ir) is added to the previous equation, ie? = Ls * Is + Lr * Ir Where Lr is the rotor inductance. Ls and Lr differ by the transformation ratio. It should be noted that in the operation described above, while the stator current component carrying power is in phase with the stator voltage, the producing component retards the stator voltage by 90 °. This current component that produces flow results in a non-unitary stator power factor. Since the current that produces flow inherently retards the voltage by 90 °, to achieve a unit power factor on the stator side, the flow is produced by the rotor winding. To produce flow through the rotor winding, an additional component, Ird, of the rotor current must be controlled. This additional component should be above the direction of flow, as illustrated in Figure 6D.

As the flow-producing component of the rotor current (Ird) increases, the flow-producing stator current is decreased. This is due to the fact that the magnitude of the flow is kept constant by the constant stator voltage (from equation 2 above). The flow-producing component of the rotor current, Ird, can be controlled in such a way that the flow it produces induces the same voltage as the network voltage. That is, the induction voltage is in phase and has the same magnitude as the network voltage. In this case, the induced voltages counterattack the network voltage and therefore the stator winding does not draw current from the stator. This is the case of the unit power factor of the system. It should be noted that a power factor / VAR 670 control can be incorporated into the system to control VAR production. (The product of the stator voltage Vs and the stator current vector Is) when no torque is produced) represents the VAr of magnetization required by the generator. Active Turbine Operation The power converter operates only when activated. The turbine controller activates and deactivates the power converter as illustrated in Figure 7, block 705. This turbine controller can be implemented in hardware, software or a combination of both, such as in controller or computer based systems. In a modality, the present invention uses a binary logic voltage signal to activate and deactivate the power converter referred to herein as the drive activation signal. In one embodiment, when the turbine controller is in normal operation mode, here referred to as automatic mode, the turbine controller turns the turbine toward the wind and changes the pitch of the turbine blades to a full power position. The position of full power will be well understood by those with ordinary skill in the specialty. Given enough wind, the blades begin to turn and the speed of the generator accelerates. Once the generator speed reaches a trigger speed of the pre-selected converter, the turbine controller sends the active signal from the inverter to the inverter to the power converter. In one embodiment, the pre-selected converter activation speed comprises 820 rpm. In response to receiving the drive activation signal, a start sequence of the converter begins. In one embodiment, the system initially closes the line contactor (CA) in the inverter 630, which results in the line array (in the inverter 630) that is connected to the network. A predetermined delay allows this contactor to close and any transients stabilize. In one embodiment, this predetermined delay is a delay of 1.5 seconds. One embodiment of the activation sequence is described in more detail in conjunction with Figure 7, and blocks 714, 715, 716 and 717. After the contactor closes, a preload cycle of the conduit occurs to ensure that the conduit Fully charged and allow instantaneous torque regulation. In this case, the duct voltage CD is regulated to a predetermined number of volts. In one embodiment, the predetermined number of volts comprises 750 volts CD. Another delay can be used to ensure that the conduit is preloaded enough to regulate properly. In one mode, this delay can be 5 seconds. In one embodiment, if the conduit fails to regulate, a voltage fault is generated over / under the conduit, and a converter fault is sent to the turbine controller. When the generator speed reaches a pre-selected or higher speed and the predetermined duct delay has expired (after full duct loading for 5 seconds); the stator contactor closes (block 714), thus energizing the stator windings and producing a rotating stator flux. The stator windings are only energized with voltage. Due to the inductance of the stator windings, the inrush current is very small and in one mode, only 75% of the maximum operating current. In one embodiment, the pre-selected speed is 900 rpm. A delay can be used to allow the stator contactor to close and stabilize the transients. In one mode, the delay is 3 seconds. When the generator speed reaches a preselected speed or higher, and the rotor voltage is verified to be below a predetermined voltage peak, the rotor contactor closes (block 715) connecting the generator matrix to the rotor of the generator. induction of the wound rotor. In one embodiment, the preselected speed comprises 1,000 rpm and the predetermined voltage peak is 318 volts. A delay can be used to allow the rotor contactor to close. In one mode, this delay is 1/2 seconds. Up to this point, the IGBTs on the rotor side (in the 624 inverter) are not switched. Since the IGBTs on the rotor side are not yet switching, there is no current flow and there is no transient or power output. Because there is no real power (only reactive power) no torque peaks are generated. The production of the power begins with the electronic switching of the IGBTs on the rotor side, which creates the current vector (both magnitude and position) required to produce the desired torque. In one embodiment, the current vector is created in response to a command from a torque controller (eg processor). Initially, this torque rises in ramp from zero to the specified value for the optimal torque-torque / power curve. The ramp increase (block 716) eliminates increases in torque to power and allows the turbine to be brought in line evenly. It should be noted that the timing of the present invention is different from the traditional "synchronization" process employed in squirrel-cage or synchronous induction machines; In the present invention, there are no breakthroughs, transients or power oscillations associated with bringing the turbine online. Once synchronized, the power converter follows the speed-power curve described above (block 717) until it is deactivated by the turbine controller.

It should be noted that the delays discussed above with respect to the starting sequence of the converter can be adjusted based on the components used in the system and the environmental conditions existing at the turbine site. These adjustments can be made in software (software), physical equipment or both. In one embodiment, the power of the turbine is provided by the wind. If the wind changes speed, the power fed to the turbine changes. To compensate for changes in the power supply, the present invention provides an update process for the generator torque. Since the torque of the generator is fixed (instantaneously) by the power converter, the speed of the generator is increased according to the power formula P = T ?. The power converter, which continuously samples the generator speed, recognizes that the speed has changed and identifies the new speed and updates the desired power from the search table. The power converter determines a new torque from the desired power and, based on FOC, calculates a new current vector, which is imparted on the generator rotor. In one mode, the update process occurs every 33 milliseconds, or every two cycles for a 60 Hz line, causing the turbine to follow uniformly and accurately the speed-power curve. It should be noted that the update rate may vary or may change dynamically during operation. Below the nominal wind speed (eg region II) the blades are maintained at a preselected power capture angle, and the resulting turbine / generator speed is due to the controlled torque and the wind power feed. This ensures that the speed-power curve has been correctly chosen. In one embodiment, the preselected power capture angle is the maximum power capture angle (eg, 0, 1 or 2 degrees of pitch). The number of degrees changes as a function of wind speed. The nominal power occurs at a predetermined generator rotor speed. In one embodiment, the generator speed at which the rated power occurs is 1,423 rpm. On the nominal wind speed, the speed of the generator rotor is controlled by the PID controller that changes the pitch of the blades in response to a generator rotor speed indication. It should be noted that this indication can be in a variety of forms including, but not limited to, a signal or one or more speed values stored in a register. Importantly, the PID step controller works independently of the power converter. If the power converter fails, the PID controller maintains the generator speed (1423 rpm in one mode) by controlling higher blade pitch angles. In doing so, this system has an inter-fault safe operation. For generator speeds equal to or greater than the generator speed at which the rated power occurs (for example 1423 or more) the speed-power curve is such that the power converter maintains the power constant, and without significant fluctuations. Therefore, wind gusts above the nominal speed that tend to increase the turbine speed have little effect on the generator power, as the PID controller responds and regulates the speed of the generator rotor. The response of the PID controller, however, is such that it is able to effectively control the rotor speed and thus power increases within about 5%, resulting in an almost flat power output, for wind speeds equal to or greater than than the nominal ones. Increases over the rated power have no effect on the mains voltage, since the excess power is developed by the rotor of the winding rotor induction generator since the stator power remains constant. The rotor current (and stator current) are kept constant during these increments by the power converter by keeping the torque constant (the torque is proportional to the current). Since the rotor current is constant during these bursts, the increase in rotor power is due to an increase in rotor voltage. But the network is not affected by this increase in voltage because the power converter located between the generator rotor and the network, electronically translates this variant voltage of the rotor (and frequency) to a constant AC waveform (for example AC wave of 60 cycles 460 volts). Variable pitch control system of the whole range The variable pitch control system (VPC) of the present invention is a real-time distributed servo system for control of pitch position and rotor speed of the wind turbine . The VPC verifies and controls the position of blade pitch, step speed and rotational speed of the generator. In one embodiment, a pitch position transducer supplies an analog signal that is proportional to the pitch position of the blade, and subsequently converts to digital, to identify the current position of the turbine blades. A blade actuator coupled to the blades is used to mechanically change the pitch of the blades. Figure 7 is a flow diagram illustrating one embodiment of the pitch regulation system of the present invention. The control of the processing logic in the system performs some operations in cooperation with electrical / mechanical physical equipment in the system. The control / processing logic can be implemented in physical equipment, software (software) or a combination of both, such as a computer system or controller. With reference to Figure 7, the pitch regulation system begins by measuring the rotor speed (block 701). At the same time, the system determines its operational state (block 702). A test determines whether the step control system is in automatic mode (block 703). If the operating state of the system is not automatic mode, a test determines whether the speed of the generator rotor (in rpm) is less than a predetermined speed (block 704). In one embodiment, the predetermined speed is 1035 rpm. If the system is not in automatic mode, and the generator rotor speed is lower than the predetermined speed, the power converter is signaled to enter a deactivation sequence (processing block 705); otherwise the system remains in its current state. If the system operates in automatic mode, the processing continues in block 706, where a test determines whether the rotor speed of the generator is increased. If the generator rotor speed does not increase, a test determines whether the rotor speed of the generator is less than a predetermined set point (block 707). In one embodiment, this predetermined set point is 835 rpm. If the generator rotor speed does not increase and is less than 835 rpm, the power converter is signaled to enter a deactivation sequence (block 705); otherwise, the system remains in its current state. In one embodiment, the deactivation sequence comprises advancing downstream the rotor current (block 708) disconnecting the rotor from the generator (block 709) and disconnect the generator stator (block 710). If the generator rotor speed is increased as determined in block 706, a test determines whether the rotor speed of the generator is greater than 100 rpm (block 711). If the speed of the generator rotor is greater than 100 rpm, the pitch is adjusted to a predetermined fixed point (processing block 713).

In one mode, the default fixed point is 0o. In other embodiments, the step may be adjusted to any number of degrees or portions thereof, including one, two or three degrees in one embodiment, the predetermined set point is variable. Also, if the rotor speed of the generator is greater than 100 rpm, a test determines whether the speed of the generator rotor is greater than a predetermined speed (block 712). In one embodiment, this predetermined speed is 820 rpm. If the rotor speed of the generator is greater than this predetermined speed, the converter is signaled to enter an activation sequence (processing block 705). Therefore, in this embodiment, the power converter is activated when the generator rotor speed is greater than 820. In one embodiment, the activation sequence comprises the following steps. First, the generator stator is connected to the network (block 714). After connecting the generator stator, the generator rotor is connected (block 715). After connecting the generator rotor, the flow component of the generator rotor current Ird is ramped (block 716) and then the generator torque is regulated (block 717). This activation sequence is a passive synchronization technique that connects the generator to enter in line with the rotor current at zero. This is possible with the vector control in cooperation with the induction generator of the wound rotor of the present invention. If the test determines that the rotor speed of the generator increases but is not yet above 100 rpm (block 711), the pitch is adjusted to a predetermined number of degrees (block 718). In one mode, the step is adjusted to 25 °. It should be noted that this step is a set point that can be varied. The step should be chosen to obtain extra lift to help accelerate the turbine faster. The present invention also performs the step placement portion of the system. At the beginning, the step position is measured using a well-known measuring device (block 720). After measuring the step position, the step position error between the current step and a predetermined setting step is calculated (block 721). After calculating the step position error, the step position error is amplified (block 722). With the amplified step position error, and the measured speed (block 701), the change in dynamic step speed is limited (block 723).

After limiting the dynamic step speed to a predetermined amount, a test determines whether the speed of the generator rotor is greater than a predetermined speed. In one embodiment, this set point is 1423 rpm. If the generator speed is not greater than the predetermined speed, the pitch regulation system enters the fixed pitch position mode (block 726); otherwise, the pitch regulation system enters the RPM regulation mode (block 727). Step Regulation Mode As discussed herein, pitch regulation refers to maintaining the blade pitch angle to a design operating position for operation below the rated power. In a modality, this position is at zero degrees. However, other positions can be used. The VPC performs pitch regulation by controlling a negative voltage that causes the pitch cylinder to move from its initial position (eg 90 °) or flag position at a constant speed of some number of degrees (eg 1.0) , per second to its nominal zero degree set point. In the present invention, a position command voltage is applied to an error amplifier, to produce an error output that is proportional to the difference between the command position (Pe and the feedback position (Pf). , the error amplifier is generated by software, however, this amplification can be done in physical equipment, the output error is amplified and sent to the proportional valve, a proportional speed imitator is used to limit the step speed initially to This limits the acceleration of the rotor with both low and high winds and allows a smooth transition to generation without problems of excessive speed.Once the turbine has reached its zero degree position, the proportional amplifier helps in maintaining this position when generating a voltage that is proportional to any error that would be incurred due to pressure bleeding from the hydraulic system. during the initial step to the operational step angle, the speed of the generator does not exceed a predetermined speed (for example 100 rpm) then the system changes the pitch to the blades to a predetermined value (for example 25 °). This helps the rotor start turning with very light winds. Once the generator speed is above the predetermined speed, then the system shifts the blades to a nominal zero degree position. Step regulation occurs at or above rated power (ie in region II) when the generator speed is below its nominal set point (eg, 1423 rpm). In one mode, during transitions below nominal to nominal envelope, the PID system begins shifting the blades back to flagging before the generator speed reaches the nominal fixed point (for example 1423 rpm) depending on the acceleration of the generator rotor speed signal (e.g. from block 607). The regulation of step below the nominal power does not require a complete PID system because the change in the speed of passage is limited to only one degree per second. Figure 8 illustrates an embodiment of the step position mode of the present invention. With reference to Figure 8, the step position error value that is proportional to the difference between the command position (Pe) and the re-feeding position (Pf) is calculated (block 800), then a test determines if a step error is positive (block 801). If the step error is not positive, then a test determines whether the rotor speed is greater than a first predetermined speed setting point (block 803). In a modality, the predetermined speed set point is 1200 rpm as measured in block 802. If the step error is not positive and the generator rotor speed is not greater than the first predetermined speed set point, the continuous processing in block 804, wherein the step speed limit is set equal to -Yl, and is fed to the dynamic step speed limiter 805. If the rotor speed is greater than the first predetermined speed adjustment point, then a test determines whether the rotor speed is greater than a second higher predetermined speed adjustment point (block 806). In one embodiment, the second predetermined speed adjustment point is 1250 rpm. If the rotor speed is higher than the second predetermined speed adjustment point, then the continuous processing in block 807, where the nominal value of pitch speed Y is set to -Y2 and is fed to the step speed limiter dynamic 805. If the rotor speed is not greater than the second predetermined speed adjustment point, then the step speed limit value Y is set to a function of the rotor speed (block 808) which is between -Yl and -Y2, and the step speed limit value Y is sent to the dynamic step speed limiter (block 805). In one mode, this function is a linear function of the step speed limiter that advances in ramp between minimum and maximum. If the step error is positive, then a test determines whether the rotor speed is greater than a third predetermined speed setting point (block 809). In one embodiment, the third predetermined speed adjustment point is 1100 rpm. If the step error is positive and the rotor speed of the generator is not greater than the third predetermined speed adjustment point, the continuous processing in block 810 where the step speed limit Y is set equal to Y1 and feeds the dynamic step speed limiter (block 805). If the rotor speed is greater than the predetermined third speed adjustment point, then a test determines whether the rotor speed is greater than a fourth predetermined speed adjustment point (block 811). In one embodiment, the fourth predetermined speed adjustment point is 1150 rpm. If the rotor speed is greater than the fourth predetermined speed adjustment point, then continuous processing in block 812, where the step speed limit value Y is set to Y2 and fed to the dynamic step speed limiter (block 805). If the rotor speed is not greater than the fourth predetermined speed adjustment point, then the limit value of the step speed Y is adjusted to a function of the rotor speed (block 813), which is between Y1 and Y2, and the step speed limit value Y is sent to the dynamic step speed limiter (block 805). In this way, the function is in the opposite direction of the function of block 808 described above. In one mode, this function is a linear function of the step speed limiter that advances in ramp between Y1 and Y2, a maximum and a minimum, respectively. The step position error value determined in block 800 is amplified (block 814) and fed to the dynamic step speed limiter (block 805). In response to the step speed limit value Y and the amplified step position error value, the step speed change is initially limited to one degree per second to limit rotor acceleration with both low and high winds and to allow a smooth transition for smooth generation of excessive speed. A test determines whether the measured rotor speed of block 812 is greater than a fifth predetermined speed adjustment point (block 815). In one embodiment, the fifth predetermined speed adjustment point is 1423 rpm. If the measured rotor speed is greater than the fifth predetermined speed adjustment point, the system enters the rpm regulation mode (block 816). On the other hand, if the measured rotor speed is not greater than the fifth predetermined speed adjustment point, then the step speed is adjusted to a programmed value (block 817) which can be represented as a binary voltage, and the processing continues in block 818. In block 818, a test determines whether the system is in automatic mode. In one embodiment, this test is determined by examining whether the system is in a fail-mode mode with stop / rest as a result of a failure detected in block 819. If the system is not in automatic mode, the continuous processing in the block 820, where the step control is exceeded to turn off the system. In one mode, the system shuts off when the blades change to 90 °. If the system is in automatic mode, then the binary voltage representing the programmed values is converted to analog (block 821) and displaces a proportional valve of the hydraulic system (block 822). In one embodiment, a simple digital-to-analog converter (D / A) generates the voltage required by the hydraulic proportional valve. This voltage is directly proportional to the speed of the hydraulic step cylinder, i.e. the rate of change of the blade pitch position. In one embodiment, a positive voltage causes the blades to change their pitch to the direction of flagging (step to flagging), while a negative voltage causes the blades to change their pitch to the power direction (power step). The step speed is controlled by the amplitude of the output voltage V / A. In one embodiment, a V / A output sample rate is set at 10 Hz. RPM regulation mode The VPC system regulates the generator speed. In one embodiment, the generator speed is regulated by a proportional, integral and derivative (PID) control of the pitch angle of the turbine blades, the VPC system calculates and then subsequently amplifies an error by software in one mode, to produce a output error that is proportional to the difference between the control speed (for example 1423 rpm) which is referred to herein as Rc, and the rate of feedback, referred to herein as Rf. The present invention uses this output to generate PID values required for correct speed control of the proportional valve and therefore the blade pitch angle. When the rotor speed approaches a predetermined set point (for example 1423 rpm), the PID controller generates a voltage that changes the pitch of the blades towards flagging. On the contrary, when the rotor speed falls below the predetermined set point (for example 1423 rpm), the PID controller generates a voltage that changes the pitch of the blades to power again until the nominal pitch adjustment is reached or exceeds the nominal predetermined set point (for example 1423 rpm). The controller for PID speed regulation is a speed based system. In a modality, a table is used to change the step velocity values generated by the PID control logic at specific voltages that are applied to the proportional value. An exemplary table is illustrated in Table 2. In one embodiment, the rate of change from step to maximum flag is 12 ° per second while the rate of change from maximum power step (during speed regulation) is 8o per second. second. These correspond to output D / A voltages of 5.1 and 4.1 respectively. Table 2. Translation table of step speed to impulse voltage.

It should be noted that table 2, a negative step speed is a step to power, while a step rate or zero is step to flag. In one embodiment, a valve control switch shuts off the proportional valve during the stop and rest modes as instructed or controlled. Figure 9 illustrates a mode of rpm regulation mode of the present invention. With reference to Figure 9, in block 900, the speed error value which is proportional to the difference the control rpm (Pe) of block 930 and the measured rpm (Pf) of block 902 (block 900), is calculate A test determines if the rpm error is positive (block 901). If the speed error is not positive, then a test determines whether the rotor speed is greater than a first predetermined speed adjustment point (block 903). In one embodiment, the predetermined speed set point is 1200 rpm. If the rpm error is not positive and the generator rotor speed is not greater than the first predetermined speed adjustment point, continuous processing in block 904 where the step speed limit value is set to -Yl and it is sent to the dynamic step speed limiter 905. If the rotor speed is higher than the first predetermined speed adjustment point, then a test determines whether the rotor speed is higher than the second higher predetermined speed setting point ( block 906). In one embodiment, the second predetermined speed adjustment point is 1250 rpm. If the rotor speed is higher than the second predetermined speed adjustment point, then continuous processing in block 907 where the step speed limit value Y is set to -Y2 and fed to the dynamic step speed limiter 905. If the rotor speed is not greater than a second predetermined speed adjustment point, then the step speed limit value Y is set to a function of the rotor speed (block 908). In one mode, this function is a linear function of the step speed limiter that changes in ramp between -Yl and -Y2. The step speed value Y is sent to the dynamic step speed limiter (block 905).

If the speed error is positive, then the step speed limit value Y is set to Y2 (block 912) and fed to the dynamic step speed limiter (block 905). Also after calculating the speed error value, the PID system determines whether the acceleration is too fast and adjusts the conformity step (block 940). In response to the step speed value Y and the output of the PID loop 940, the step speed is initially limited to one degree per second (block 905). Then, a test determines whether the measured rotor speed (block 902) is greater than a third predetermined set point (block 915). In one embodiment, the third predetermined speed adjustment point is 1423 rpm. If the measured rotor speed is lower than the third predetermined speed adjustment point, the system enters the step position mode (block 916). On the other hand, if the measured rotor speed is greater than the predetermined third speed adjustment point, the step speed is converted using the step speed to direct the voltage translation table described above (block 917), and the continuous processing in block 918. In block 918, a test determines whether the system is in automatic mode. In one embodiment, this test is determined by examining whether the system is in stop / standby failure mode as a result of a failure detected in block 919. If the system is not in automatic mode, processing continues in block 920 , where the step control is exceeded for the system. In one mode, the system shuts down when changing the pitch of the blades to 90 °. If the system is in automatic mode, then the voltage representing the step speed value is converted to analog (block 921) which is applied to the proportional valve of the hydraulic system to initiate the step change action (block 922). A step system with a PID controller Figure 10A illustrates a mode of a step system. With reference to Figure 10A, the step system comprises a closed-loop PID controller 1010 and a non-linear table 1011 for converting step-speed feeds to voltage outputs. The step velocity values received by the table 1011 are generated by the PID controller 1010 in response to a difference in the output speed and the control rate, as determined by the comparison logic or software.

The voltage outputs of Table 1011 are applied to a proportional value that results in blade pitch action. A block diagram of the functional flow of a PID controller mode is illustrated in Figure 10B.

With reference to Figure 10B, a difference between the position feedback value, Pf, is determined from the control position, Pe, by comparison logic (for example a subtractor) or software 1001. This difference represents the position error. The position error is amplified by a scale factor of K by the amplifier 1002, to create a value Ye. In one embodiment, K is set to 0.5, the value Ye is coupled as a power to the limiter 1005, which is regulated by the limiting controller 1004. The limiter 1005 limits the speed of the blades passing during step position movements. In one mode, the pace is slow. The controller 1004 is coupled to receive the generator speed feedback, and in response thereto, the limiter 1005 changes based on the generator speed (in rpm). The limiting controller (block 1004) advances in maximum ramping step of flagging or passage to power speed or nominal power using a linear function of measured value of rpm, RF. The PID controller also comprises comparison logic (for example a substrate A) or software 1003 to generate a difference between the controlled generator speed, Rc, and the current generator speed, Rf. The output of the comparison block 1003 is the speed error value x, which is received by the PID algorithm blocks 1006 and 1007. The PID algorithm (blocks 1006 and 1007) calculates a desired step velocity based on a proportional function , integral and derivative of the speed error value. The step speed output as a function of the speed error feed may also include gain programming which adjusts gains as a function of the pitch position. A programmed step rate (block 1012) provides the multiplier, E, based on the pitch position feedback and two setpoint parameters El and E2. In one embodiment, the two adjustment parameters El and E2 are = -0.85 and 0.0028 respectively. The output of the block 1005 is coupled to the output 1006 and YF to feed the block 1008. The limiter 1005 limits the maximum step-to-flag-pass rate and power-up during speed regulation mode. The output of the limiter 1008 provides the supply of a voltage generator 1009 and feeds back into the PID algorithm block 1007. The output of the voltage generator 1009 is coupled to the supply of the switch 1010 which is controlled to shut off the proportional valve in response to a command to stop the turbine. The output of the switch 1010 is coupled to a D / A converter 1011 that provides the voltage output for the system that is applied to the proportional value that shifts the blade pitch action. Dynamic Braking In order to achieve dynamic braking, the torque-speed curve of the present invention can be deliberately biased. In one embodiment, the power converter directs a maximum constant torque. This maximum constant torque is commuted in the system in response to a fault condition, causing the turbine speed to decrease. Figure 6B illustrates the power converter including a maximum constant torque 660 and switch 629. In one embodiment, the safety system initially applies a soft brake and pitch change to the blades at 90 °. Subsequently, a test determines if there has been a failure. In one mode, dynamic braking is only used in response to failures by hard standing. In other modalities, dynamic braking can be used for other types of faults (for example, soft, hard, etc.). In response to determining that a hard stop failure occurred, the present invention changes the pitch of the blades to 90 ° and directs the value of maximum constant torque. The torque is imparted on the generator rotor resulting in a decrease in the turbine speed. In one embodiment, the turbine is braked at a predetermined speed. After reaching the predefined speed, braking can be released either automatically or manually, for example by manual restart by the operator. Power factor and VAR compensation. Since the power control regulates the rotor current directly, the power factor of the total system can be dynamically controlled and adjusted over a range of 0.90 delay to 0.90 forward, regardless of the output level of the turbine. In the present invention, the VARs are supplied to the secondary of the induction generator. In this way, the power converter can act as a VAR compensator for the service. This is achieved by a control system that directs a specific number of KVARs from each turbine through a SCADA system. Figure 6B illustrates a power 670 for controlling the VARs. By adjusting the supply of VARs to the secondary, the VARs of the total system can be selected dynamically. The desired power factor can be adjusted to any nominal value between 0.90 of delay and 0.90 of forward or vary in response to fluctuations in mains voltage. Therefore, the power converter that works through SCAVA can operate in a constant power factor mode, constant VAR mode or a voltage regulation mode. Some of the benefits of power conditioning of the present invention is that it provides maximum power capture, torque control, voltage jitter elimination, as well as power factor control. In addition, dynamic power factor adjustment is available. Furthermore, the variable speed of the present invention allows to mitigate peaks of torque. Torque transients that cause voltage fluctuation and damage to pulse train components are attenuated by allowing an increase in rotor speed, thus "storing" the additional energy of a wind gust in an inertia rotation of the rotor blades. This energy can be extracted and fed to the network by reducing the speed of the rotor as the wind gust fades or can be "discharged" by changing the pitch of the blades away from the wind. In this way the variable speed operation can dramatically reduce torque transients which results in lower cost and longer life for the wind turbine boost train. Some portions of the detailed description illustrated above are presented in terms of algorithms and representations of symbolic operations on data bits within a computer memory. These descriptions and algorithmic representations are the means employed by those skilled in the data processing specialty to more efficiently transport the substance of their work to others with skill in the specialty. An algorithm here and in general is conceived as a self-consistent sequence of steps leading to a desired result. The stages are those that require physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored transferred, combined, compared and otherwise manipulated. It has proven convenient at times, mainly for reasons of common use, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers or the like. It must be kept in mind however that all these terms and the like will have to be associated with the appropriate physical quantities and are simply convenient labels applied to these quantities. Unless specifically stated otherwise as it is apparent from the following discussions, it will be appreciated that through the present invention, discussions using terms such as "processing" or "computation" or "calculation" or "determination" or "display" or the like may refer to the action and processes of a computer system or similar electronic computing device that manipulates and transforms data from represented as physical (electronic) quantities within the records and memories of the computer system into other data similarly represented as physical quantities within the memories or records of the computer system or other devices storage of transmission or display of information. Also, as discussed above, the present invention relates to an apparatus for performing the operations. This apparatus can be specially constructed for the required purposes, or it can comprise a general purpose computer selectively activated or reconfigured by a computer program stored in the computer. This computer program may be stored in a computer-readable storage medium such as, but not limited to, any type of disk including floppy disks, optical disks, CD-ROMs, and magneto-optical disks, read-only memories (ROMs), memories random access (RAMs), EPROMs, EEPROMs, magnetic or optical cards or any type of suitable medium for storing electronic instructions, and each one coupled to a computer system conduit. The algorithms presented here are not inherently related to any computer or other particular device. Various general-purpose machines can be used with programs in accordance with the present teachings, or they can prove to be convenient for building more specialized apparatuses to perform the required method steps. The structure required by a variety of these machines will appear from the following description. In addition, the present invention is not described with reference to any particular programming language. It will be appreciated that a variety of the programming language may be employed to implement the teachings of the invention as described herein. While undoubtedly, many alterations and modifications of the present invention will be apparent to a person with ordinary skill in the art after having read the foregoing description, it will be understood that the particular mode shown and described by way of illustration is in no way intended to be be considered as limiting. Therefore, references to details of the various embodiments are not intended to limit the scope of the claims which in themselves describe only those features considered essential for the invention.

In this way, a variable speed system has been described.

Claims

CLAIMS 1.- A variable speed wind turbine system, characterized in that it comprises: an induction generator with coiled rotor, a torque controller coupled to the generator to control generator torque using field oriented control; and a step controller coupled to the generator to perform pitch regulation based on the speed of the generator rotor and operating independently of the torque controller.
2. The system according to claim 1, characterized in that the step controller comprises a proportional, integral, derivative step controller (PID = Proportional, Integral, Derivated).
3. The system according to claim 1, characterized in that the step controller comprises a proportional, integral step controller (Pl = Proportional, Integral).
4. The system according to claim 1, characterized in that the step controller comprises a proportional, derived step controller (PD = Proportional, Derivative).
5. - The system according to claim 1, characterized in that the step controller comprises a delay-advance controller.
6. The system according to claim 1, characterized in that the step controller comprises an advance-delay controller.
7. The system according to claim 1, characterized in that the step controller comprises an open loop controller with a derivative term.
8. The system according to claim 1, characterized in that the induction generator with winding rotor comprises an induction generator with non-rubbing ring.
9. The system according to claim 1, characterized in that the torque controller comprises a damping filter to reduce the controlled torque based on the movement of oscillation detected between turbine blades and the generator.
10. A variable speed system, characterized in that it comprises: induction generation means with coiled rotor to generate power; a means for controlling torque, for controlling generator torque using field-oriented control; and a step control means for performing pitch regulation based on generator rotor speed and operating independently of the torque controller.
11. The system according to claim 10, characterized in that the step control means comprise a controller proportional, integral, derivative (PID).
12. A variable speed wind turbine system, characterized in that it comprises: an induction generator with coiled rotor, a torque controller coupled to the generator to control generator torque using field oriented control; and a controller proportional, integral, derivative (PID = Proportional, Integral, Derivative) coupled to the generator to perform pitch regulation based on the speed of the generator rotor.
13. The system according to claim 12, characterized in that the induction generator with winding rotor comprises an induction generator with non-rubbing ring.
14. The system according to claim 12, characterized in that the power controller controls the power of the generator and the torque as a function of the speed of the generator.
15. - The system according to claim 12, characterized in that the power controller controls the power of the generator from a look-up table (LUT = Look Up Table) as a function of the generator speed using field-oriented control (FOC) = Field Oriented Control).
16. The system according to claim 12, characterized in that the power controller comprises a search table (LUT) of power and corresponding generator rotor speeds., and wherein the power controller interpolates the LUT using a measured generator rotor speed, to determine a target output power, from which the torque controller determines a desired generator torque using the speed of generator rotor measured.
17. The system according to claim 16, characterized in that the power controller causes the generator to follow a predetermined power-speed curve encoded in the LUT.
18. The system according to claim 12, characterized in that the power controller comprises: a LUT that encodes a predetermined speed-power curve, wherein the LUT outputs a target output power, in response to a speed of the measured generator rotor; a comparator to generate a power error indication based on a comparison of the current output power to the target output power; a proportional, integral controller (Pl = Proportional Integral) coupled to the power error indication, to generate a current output power adjusted in response to the calculated power error indication; and a divider for generating a controlled torque in response to the measured generator rotor speed and the adjusted current output power.
19. The system according to claim 18, characterized in that it further comprises a damped term filter with forward correction coupled to change the controlled torque in response to the speed of the measured generator rotor.
20. The system according to claim 12, characterized in that the power controller controls the generator torque by controlling a required rotor current vector that interacts with an identified flow vector to produce a generator torque. wanted.
21. The system according to claim 12, characterized in that the power controller controls the torque at least nominal cutting wind speeds.
22. - The system according to claim 12, characterized in that the power controller controls the torque from cut-off to nominal wind speeds.
23. The system according to claim 12, characterized in that the power controller causes the generator to follow a predetermined power-speed curve.
24. The system according to claim 12, characterized in that the power controller controls a preselected constant torque to brake the coiled rotor.
25. The system according to claim 24, characterized in that the preselected constant torque comprises a maximum preselected constant torque.
26.- The system according to claim 12, characterized in that it also comprises a generator speed indication coupled to power controller and controller supplies. PID
27. The system according to claim 12, characterized in that the power controller operates independently of the PID step controller.
28. - The system according to claim 12, characterized in that the PID pitch controller comprises a closed loop PID controller with feedback angle.
29. The system according to claim 12, characterized in that the PID step controller comprises an open loop controller with a derivative term.
30. The system according to claim 12, characterized in that the PID step controller generates a step speed to perform pitch regulation.
31. The system according to claim 12, characterized in that it also comprises a wind turbine having at least one blade coupled to the generator, and wherein the PID step controller controls the speed of the generator rotor when changing the pitch of the generator. minus one blade.
32. The system according to claim 31, characterized in that the step controller changes the pitch of at least the blade at least based on a difference in rotor speed of the current generator and rotor speed of the controlled generator.
33. The system according to claim 12, characterized in that it further comprises: a comparator for generating speed error indication based on a comparison between a measured generator rotor speed and a rotor speed of the target generator, and in where the PID step controller generates an output step speed value, in response to the speed error indication; and a coupled non-linear LUT (search table) for outputting a controlled voltage to direct a proportional value to effect a step change action in response to the step speed value.
34.- A variable speed wind turbine having a plurality of blades, characterized in that it comprises: a double feed generator having a coiled rotor; a power converter coupled to the coiled rotor of the dual power generator having a search table (LUT) containing an encoded power-speed curve, wherein the power converter samples the speed of the generator rotor updates a desired output power of the LUT using the generator rotor speed, determines a new torque based on an updated desired output power and calculates a new current vector that is printed on the coiled rotor; and a closed loop proportional, integral, derivative (PID) step controller, coupled to change the pitch of the plurality of blades based on the speed of the generator rotor.
35.- The turbine according to claim 34, characterized in that the power converter and the PID step controller operate independently.
36.- The turbine according to claim 34, characterized in that the power converter maintains the constant power over the nominal wind speeds.
37.- The turbine according to claim 36, characterized in that the power converter maintains constant power by controlling the rotor current to provide the proper torque.
38.- The turbine according to claim 34, characterized in that the PID step controller generates a step speed to perform pitch regulation.
39.- The turbine according to claim 34, characterized in that the step controller changes the pitch of the plurality of vanes based on a difference in current generator rotor speed and controlled generator rotor speed.
40. - The turbine according to claim 34, characterized in that it further comprises: a comparator for generating speed error indication based on a comparison between a measured generator rotor speed and a rotor speed of the target generator, and wherein the PID step controller generates a step speed command in response to the speed error indication; and a non-linear LUT coupled to output a pulse voltage to be applied to a proportional value to achieve blade pitch movement in response to the step speed command.
41. A variable speed wind turbine having a plurality of vanes, characterized in that it comprises: means for generating double power to generate power, wherein the generating means have a coiled rotor; means for converting power to transform alternating current into direct current, wherein the means for converting power has an LUT containing an encoded speed-power curve, wherein the means for converting power includes means for sampling the generator rotor speed , means for updating a desired output power from the search table (LUT) using the generator rotor speed, means for determining a new torque based on an updated desired output power and means for calculating a new vector of current that is imparted on the winding rotor; and means for control of proportional, integral, derivative (PID) closed loop, to change the pitch of the plurality of vanes based on the speed of the generator rotor.
42. The turbine according to claim 41, characterized in that the means for converting power and the means for PID pitch control operate independently.
43. The turbine according to claim 41, characterized in that the means for converting power include means for maintaining the power constant over the nominal wind speeds.
44. The turbine according to claim 43, characterized in that the means for converting power include means for maintaining constant power by controlling the current of the rotor to provide the proper torque.
45.- A method for controlling the power of the generator, characterized in that it comprises the steps of: measuring the speed of the generator rotor; access a search table (LUT) using the measured rotor speed to obtain a target output power; compare the current output power and the target output power; generate a controlled torque when adjusting a torque calculation to maintain a predetermined output, based on comparison of the current output power to the target output power.
46. The method according to claim 45, characterized in that the controlled torque comprises a predetermined constant torque to brake the speed of the generator rotor.
47. The method according to claim 45, characterized in that the predetermined constant torque comprises a maximum constant torque.
48.- An apparatus for controlling the power of the generator, characterized in that it comprises the steps: * means for measuring the speed of the generator rotor; means for accessing a search table (LUT) using the measured rotor speed to obtain a target output power; means for comparing the current output power and the target output power; means for generating a controlled torque by adjusting a torque calculation to maintain a predetermined output based on comparison of the current output power to the target output power.
49. - Method for controlling generator torque of a variable speed system, the method is characterized in that it comprises the steps of: identifying a stator flow vector; control a rotor current vector; and producing a torque of the desired generator by interacting the stator flux vector and the rotor current vector.
50.- A synchronization process for a variable speed system that has a generator, the process is characterized in that it comprises the steps of: connecting a generator stator; connect a generator rotor; advance a rotor current in ramp; and regulate the torque of the generator.
51.- The process according to claim 50, characterized in that the step of connecting the generator stator occurs at a first generator speed.
52. The process according to claim 51, characterized in that the step of connecting the generator rotor occurs at a second higher generator speed than the first generator speed and when the rotor voltage is at a first value.
53. The process according to claim 52, characterized in that the step of regulating the generator torque comprises the steps of activating a rotor-side converter and switching the rotor-side IGBTs.
54.- The process according to claim 52, characterized in that the step of regulating the generator torque comprises the step of creating a current vector that is capable of producing the desired torque.
55.- A variable speed wind turbine system, which has turbine blades, the system is characterized in that it comprises: an induction generator with coiled rotor, a torque controller coupled to the generator to control generator torque, wherein the torque controller comprises a damping filter for reducing controlled torque based on the oscillation movement detected between the turbine blades and the generator; and a step controller coupled to the generator to perform pitch regulation, based on the base speed of the generator rotor and operate independently of the torque controller.
56.- The system according to claim 55, characterized in that the damping filter comprises a band pass filter with a pass band centered on the resonant frequency of the generator and the turbine blades and an arrow that couples the generator and the turbine blades with each other.