CN101501981B - Dynamic electric brake for a variable speed wind turbine having an exciter machine and a power converter not connected to the grid - Google Patents

Abstract

A variable speed wind turbine having a doubly fed induction generator (DFIG), includes an exciter machine mechanically coupled to the DFIG and a power converter placed between a rotor of the DFIG and the exciter machine. Thus, the power converter is not directly connected to the grid avoiding the introduction of undesired harmonic distortion and achieving a better power quality fed into the utility grid. Moreover, the variable speed wind turbine includes a power control and a pitch regulation.

Description

Have exciter and be not connected to the electric power converter of electrical network, variable speed wind turbines and the system and the braking method of dynamic dynamo-electric brake

The cross reference of related application

The priority that No. the 60/783rd, 29, No. the 11/477th, 593, the U. S. application that the application requires to submit on June 30th, 2006 and the U.S. Provisional Application of submission on March 17th, 2006, its disclosure all is incorporated into this by reference.

Technical field

The present invention relates to the variable speed wind turbines field, and relate to the variable speed wind turbines of the static transducer in centre, power control and pitching (pitch) adjusting that comprise double fed induction generators (DFIG), exciter, be not connected to electrical network particularly.

Background technology

In recent years since, wind-driven generator increases in the whole world considerablely.Even this industry has risen to ripe level with technology in this field, but estimates at large that still this growth will continue following many decades.Total radix of the wind capacity of installing along with the wind energy turbine set increase in size continues to increase, and the importance that improves the power output quality becomes for wind-force developer and the same vital challenge of public utilities client.

Electric power transmission is a process that electric power is delivered to the client.Power transmission system is commonly referred to " electrical network (grid) ".Transmission of electricity company must tackle the challenge that obtains maximum dependable capacity from each transmission line.Yet owing to consider the stability of a system, actual capacity maybe be less than the physical restriction of circuit.Therefore the electric power source that needs good cleaning is to improve the stability of a system.

In majority was used, wind turbine generated electrical power and will feed current in the electrical network.This possibly cause the skew of local power grid voltage, such as electric current injection of the change of steady state voltage level, dynamic electric voltage variation, flicker, nonsinusoidal waveform (being harmonic wave) etc.

These effects possibly be undesirable for the end user device that is connected to electrical network and other generator or parts such as transformer.Along with power capacity increases, obviously need to improve the power quality characteristic of turbine output.The technology that it is involved is depended in the power quality influence of wind turbine.Although this fact is arranged, wind turbine manufacturer does not consider power quality as main design feature.

Initial wind turbine was designed in order in fixedly rotary speed work originally.According to this model, the generator of wind turbine directly is connected to electrical network and at the speed operation of confirming, thereby allows very little velocity variations.Under the situation of asynchronous electricity generating device, only allow slip (slip) scope of generator.This slip is the difference that the rotary speed of rotor is compared with the rotating magnetic field of stator.The slip of generator slightly changes with the power quantity that generates, so it is also constant by halves.In addition, these wind turbines need starting current restriction strategy and idle (reactive) energy compensating unit in course of normal operation.Undesirable torque below the wind eddies stream changes, and this torque changes the drive chain that directly is transferred to wind turbine and therefore is transferred to the active power of presenting to electrical network.

Keeping rotary electrification motor speeds and the proportional one type of wind turbine of wind speed is variable speed wind turbines.In order to obtain the maximal efficiency of wind turbine, the generator rotary speed is adapted to the wind speed that fluctuates.This type wind turbine comprises the power electronic converter that is connected to electrical network.Because this a kind of interface, be fed in the electrical network from the harmonic emissions of the power electronic converter of turbine.

Use the variable speed model wind turbine of power electronic converter to become general at present.The example of this variable speed wind turbines is at United States Patent (USP) the 5th, 083, and No. 039, No. the 5th, 225,712, United States Patent (USP) or the U.S. openly apply for being described in 2005/0012339.Based on these turbines of full converter system comprise generator, in transducer, the DC link bus of generating pusher side be connected to the meritorious transducer (active converter) of electrical network.The frequency conversion energy of generator is sent to the DC link bus and is converted to fixed frequency by the meritorious transducer of grid side subsequently by the transducer of generating pusher side.Some shortcomings are that all full converter system is common.The semi-conductive meritorious switch of the transducer of grid side is injected into electrical network with undesirable high-frequency harmonic.For fear of by the caused problem of these harmonic waves, a plurality of filters must be installed.In addition, because different resistance values on the electrical network and because the harmonic wave that is pre-existing in, so according to the characteristic of wind energy turbine set position and needs different tuning to filter.

Another variable speed wind turbines is at United States Patent (USP) the 6th, 137, is described in No. 187.As shown in fig. 1, this wind turbine configuration comprises that double fed induction generators (1) and power converter (4), this power converter comprise the meritorious transducer (7) of meritorious transducer (5), dc bus (8) and the grid side of rotor-side.In this configuration, all the only few part in the power is sent to electrical network (9) through transducer (5,7).Power can directly be delivered to electrical network (9) by stator (3), and rotor (2) can be that metasynchronism or supersynchronous operation come to arrive electrical network (9) via power converter (4) absorbed power or power supplied according to double fed induction generators.The variable speed operation of rotor have that many very fast variable power are not transferred to network but by the action of the flywheel of rotor level and smooth advantage.Yet the use that is connected to the power electronic converter (4) of electrical network (9) has caused the harmonic distortion of network voltage.

Other document has also been described variable speed wind turbines.For example, United States Patent (USP) the 6th, 933 has been described following speed change system No. 625, and this speed change system comprises double fed induction generators and has the rectifier of the passive grid side of the relevant control with pitching of nominal power control.Under this situation, have in the rectifier of the meritorious transducer of rotor-side, passive grid side and the switchable power dispersion unit that on the DC link bus, is connected.In supersynchronous operating process, the energy that extracts from rotor dissipates the switchable power dispersion unit, thereby reduces the efficient of wind turbine; In the operating process of wind turbine under the metasynchronism pattern, energy is by the rectifier rectification of passive grid side, and this causes undesirable low-frequency harmonics in electrical network.Therefore need complicated attentuating filter.United States Patent (USP) the 6th, 566, No. 764 with United States Patent (USP) the 6th, 856, No. 038 the variable speed wind turbines with matrix converter has been described.Two kinds of situation include the power electronic converter that is connected to electrical network, and this possibly cause undesirable harmonic voltage.

All aforesaid U.S. Patent all have the transducer that is connected to electrical network with other existing solution relevant with the variable speed wind turbines that comprises power electronic device.Look used technology on the transducer and decide, on electrical network, introduce have must through use that filter decayed and be tuned to the harmonic wave of different range of final application site, thereby make system cost higher and reliability is lower.

In view of these problems of the prior art, a kind of improvement power solution that can be applied to variable speed wind turbines need be provided.

Especially another the undesirable problem under light current net situation is the reactive power consumption in the synchronizing process at generator.For example, at United States Patent (USP) the 6th, 600, a kind of method for synchronous has been described in No. 240.This method is deactivated and rotor has reached and begins generator amature is connected to electrical network in the predetermined speed at power converter.At this moment, electrical network supply holomagnetization electric current, this causes reactive power consumption.It is unallowed that this reactive power consumption is that some new electrical networks are followed standard institute sometimes.This patent has also been described a kind of disconnection process.This process begins to reduce rotor current and inactive rotor transducer.At this moment, electrical network is supplied idle magnetizing current.In order to break off generator, make the contactor open circuit with reactive current, thus the useful life of reduction contactor.Thereby a kind of be used to the make method that double fed induction generators is synchronous, be connected to electrical network and disconnection, the life-span that this is avoided consume reactive power and increases connection device need be provided.

The power quality that decision is injected to electrical network be control on the other hand to generator.One type of control of transducer to the generating pusher side is called " towards the control of field " (FOC).The FOC method is based on electrical model and machine parameter.Because the dispersiveness of machine parameter, thus calculating torque exactly, and need additional online adjustment loop.In addition, when in electrical network, breaking down, the delay that used FOC method has been introduced in flux position sign, thus make that more being difficult to satisfy new electrical network follows requirement.

In the variable speed wind turbines of the prior art with DFIG configuration, though the maintenance of stator power is constant, rotor power also is fed in the electrical network through power converter.Because the rotor power pulsations, thus also make the gross power pulsation that is fed in the electrical network, thus influence the power output quality of wind turbine.

Only use the variable speed wind turbines of double fed induction generators can not use dynamo-electric brake.As stated, in this a kind of configuration, power directly is delivered to electrical network by stator, and a small amount of part in whole power is sent to electrical network through transducer from rotor.When the accident that wind turbine occurs stopped, for example in the sustained fault process in electrical network, the power of generator fell sharply.Have only quick on-electric braking just can be used to stop wind turbine like pitching blade.This operator scheme produces huge mechanical force in wind turbine components, this possibly cause premature damage.Therefore need be in order to prevent the additional brake of this mechanical stress.

In patent WO01/25628 number, described in wind energy turbine set, to use and comprised the high-tension dc link transmission (HVDC) of synchronous generator as basic generation unit.Owing to used synchronous motor, so output frequency changes with wind-force, therefore especially hanging down under the wind condition, it is big that the flutter component of output dc voltage becomes.In addition, output transformer and rectifier must be supers, because they must be operated at low frequency.Such as the such additional detail of the special tectonic of the rotor circuit with low inductance also is that the accurate adjusting of power output is necessary.

Summary of the invention

Aspect according to an exemplary embodiment of the present invention; A kind of variable speed wind turbines with double fed induction generators is provided; This variable speed wind turbines has at least one or a plurality of blades, one or more generator, is coupled to one or more exciter of drive chain, by one or more active power electronic commutator that the DC link bus engages, one of them AC side is connected to the rotor circuit of double fed induction generators and another AC side is connected to exciter.The present invention has also described power control and pitch regulation.

This one side of non-restrictive example property embodiment according to the present invention, power electronic device is not connected to electrical network.Therefore, power only is delivered to electrical network through the stator of double fed induction generators, thereby avoids undesirable harmonic distortion and realize in utilities, presenting better power quality.In addition, can avoid to the use of complex filters and according to position tuning to them, thereby make system more economical and reliable.

The power output that is on the other hand of the embodiment of the invention keeps constant more than normal speed, thereby avoids apparent velocity to change and fixed power fluctuation.Because topological structure of the present invention is so power only is delivered to electrical network through double fed induction generators.Therefore avoid the power output quality of rotor power pulsations and raising wind turbine.

A kind of use electrical network flux orientation (GFO) of having described on the other hand of exemplary embodiment of the present controls exactly the variable speed wind turbines to the power of electrical network injection.This control system be it a little and do not rely on maybe significant change machine parameter do not rely on theoretical machine mould yet, thereby the better power quality that avoids the use of additional regulating loop and realize in utilities, presenting.

The method that the another aspect of exemplary embodiment of the present is to be used for synchronous double fed induction generators has been avoided being connected to electrical network/from electrical network disconnection process consume reactive power, follow standard thereby meet new electrical network.In addition, this method can be avoided the connection current peak through connection device, thereby increases the life-span of this base part.

The another aspect of exemplary embodiment of the present provides a kind of and avoids " wearing and tearing " of DC motor current-collector when the pitching of drive vane is moved and improve the lubricated of blade bearing in order to being used at DC motor.

Being on the other hand under the accidental situation about stopping of wind turbine of exemplary embodiment of the present is though the use double fed induction generators still might be used electrodynamic braking.In emergency circumstances such such as lasting electric network fault, the chance that wind turbine possibly take place stops.Then, use exciter as generator and power can be sent to dc bus from exciter.Then, can activate dynamo-electric brake and in the rheostat of chopper the discharge section electrical power, thereby help generator to stop progressively and in wind turbine components, avoid big mechanical forces.

Another aspect of the present invention is that it can be used for high-tension dc link transmission (HVDC) in the variable speed generation system.

According on the other hand; Because topological structure of the present invention; So the fixing output frequency of alternating voltage, thus allow that the more small scale of required rectifier and transformer is set and reduce VD under low wind condition flutter component so that improve the power output quality.

With understanding aforementioned wide in range description and following concrete description all only is exemplary and illustrative and do not limit the present invention for required protection.

Description of drawings

The accompanying drawing of incorporating into has constituted the part of one or more embodiment of the present invention.Yet, should they be interpreted as the present invention is limited to specific embodiment.Will from combine with accompanying drawing the following specifically describes more fully understand the present invention and operator scheme thereof, in the accompanying drawings:

Fig. 1 illustrates the conventional speed change wind turbine system that has double fed induction generators and be connected to the power converter of electrical network;

Fig. 2 illustrates according to an exemplary embodiment to have exciter and not to be connected to the enforcement of circuit diagram of variable speed wind turbines of the power converter of electrical network;

Fig. 3 illustrates the power control that is used for variable speed wind turbines and the block diagram of pitch control subsystem;

Fig. 4 illustrates the block diagram of an embodiment of optimal power tracking Control (OPTC) method;

Fig. 5 illustrates the block diagram of an embodiment of the controller of GFO and double fed induction generators;

Fig. 6 illustrates the block diagram of an embodiment of exciter controller;

Fig. 7 illustrates synchronously, the flow chart of an embodiment of connection and break sequence;

Fig. 8 illustrates the block diagram of an embodiment of pitch control system;

Fig. 9 illustrates the block diagram of an embodiment of the voltage-regulation pattern of in synchronizing process, using;

Figure 10 illustrates the block diagram of an embodiment of the HVDC wind turbine with high-voltage generator and rectifier;

Figure 11 illustrates the block diagram of an embodiment of the HVDC wind turbine with low-voltage generator, transformer and rectifier;

Figure 12 illustrates the flow chart of an embodiment of the method that is used for the application of dynamic dynamo-electric brake.

Embodiment

Hereinafter is described the variable speed wind turbines according to various exemplary embodiments.Only come reference so that understand the present invention better in some accompanying drawings as diagram.In addition, will use identical Reference numeral to refer to identical or similar part in the whole text at specification.

General introduction

Generally speaking, the variable speed wind turbines generator of various exemplary embodiments is transported to exciter with the electrical power that rotor generates in the supersynchronous operating process of double fed induction generators according to the present invention.Exciter is changed back the mechanical rotation energy with this electric energy then, and this mechanical rotation energy can be used for further increasing the electrical power by the stator generation of sending to electrical network then.Electrical power only is delivered to electrical network by the stator of DFIG, thereby avoids power to be delivered to electrical network through power converter.Therefore improved quality to the electrical power of electrical network supply.

In addition, in the metasynchronism operating process, when rotor is not to generate electrical power, but when needing electric power source, the part of the rotating energy that wind-force generated by exciter with generating the required electrical power of rotor.

In Fig. 2, broadly show the variable speed wind turbines generator system.In this embodiment, this speed change system comprises one or more rotor blade (201), is connected to the rotor hub of drive chain.Drive chain mainly comprises turbine wheel shaft (202), gearbox (203) and double fed induction generators (205).The stator of double fed induction generators (210) can be connected to electrical network through using one or more contactor (215).This system also comprises: mechanically be coupled to the exciter (212) of drive chain, perhaps come the reversible electric machine of work as motor or dynamotor such as asynchronous machine, DC generator, synchronous (for example permanent magnetism) machine; And two the meritorious electronic power converters (222,225) (being back-to-back transducer) that engage by DC link bus (224), one of them AC side is connected to the rotor circuit of double fed induction generators and another AC side is connected to exciter (212).The active power transducer (225) of regulating exciter is not connected to electrical network, thereby active power transducer and electrical network are isolated.Replacedly, back-to-back transducer be can replace and cyclic converter, matrix converter or other any bidirectional transducer connected.This system also can comprise the dynamo-electric brake circuit (231) that is connected to dc bus, such as the DC chopper.Transducer control unit (CCU) (200) carries out the power adjustments to double fed induction generators and exciter.This system comprises dV/dt filter (220), and this filter is connected to the rotor circuit of double fed induction generators so that protect it to avoid the voltage fluctuation suddenly by the meritorious switch generation of power electronic converter.In addition, dV/dt filter (227) is connected between electronic power converter and the exciter.In one embodiment, the protection module (219) of strick precaution electric network fault is connected to the rotor of double fed induction generators.

The variable speed wind turbines generator system of in this embodiment, describing is in (being metasynchronism) below the synchronizing speed and (promptly supersynchronous) work more than synchronizing speed.In the metasynchronism operating process, power flows to the rotor (211) of double fed induction generators (205) from exciter (212), makes exciter (212) serve as generator.On the other hand, in supersynchronous operating process, power flows to exciter (212) from the rotor (211) of double fed induction generators (205), so exciter serves as motor.The power of the middle generation/consumption of consumption/generation exciter (212) in the rotor (210) of double-fed induction machine the feasible loss in different units of power-balance in the gamut rate process.

Because the topological structure of above-mentioned variable speed wind turbines generator system is so power only is delivered to electrical network through the rotor (210) of double fed induction generators (205).Be not connected to the electronic power converter of electrical network.Thereby the more high power quality of avoiding undesirable harmonic distortion and realizing in utilities, presenting.Also avoid in addition to the use of complex filters with according to the tuning demand of diverse location, thereby make system more economical and reliable them.

This topological structure also allows in the double fed induction generators configuration, to use dynamo-electric brake.For example because the outage fully of electrical network and under the situation about promptly stopping, stator is disconnected and power that generator produced can not be fed in the electrical network at wind turbine.Yet exciter (212) can be used as generator, so power can be sent to dc bus (224) from exciter (212).Therefore, the part electrical power is discharged in the rheostat of chopper.At last, application machine or pneumatic braking device such as pitching blade are to stop wind turbine.This embodiment of the present invention allows generator in DFIG configuration, to use dynamo-electric brake, thereby helps wind turbine to stop and keeping away the mechanical force that possibly cause premature damage in the rabbit wind turbine components.

The variable speed wind turbines control system comprises master controller (302), power controller and pitch regulation device as shown in Figure 3.Best power tracking control unit (OPTC) (303) comes rated output to be provided with a little based on the wind speed of measuring.This is provided with and a little sends to master controller (302) and therefore send to DFIG controller (300).DIFG controller (300) carries out total active power through meritorious electronic power converter (222) and controls the power that double fed induction generators (205) is sent to electrical network with effective adjusting of total reactive power.The power electronic control of double fed induction generators (205) is based on electrical network flux oriented (GFO).Exciter (212) is regulated by meritorious electronic power converter (225) and is controlled by exciter controller (301).Meritorious electronic power converter uses the dc bus voltage level measured by dc bus voltage transducer (223) to control to/the power that transmits from exciter (212) as the main regulation variable.

The variable speed wind turbines control system also comprises the pitch control system that is the basis with restriction exciter power demand.Based on the pitch position of pitch control subsystem device (EBPC) (304) adjusting vane of exciter so that the restriction pneumatic power.EBPC (304) is that OPTC (303) provides luffing angle to be provided with a little according to the power excursion of exciter and speed and position through measuring pitch motor (305) also.In addition, EBPC (304) comprises the anti-wear and lubricating system (CAWLS) of current-collector so that protection is used for the current-collector of the DC generator that pitching moves and improves the lubricated of blade bearing.

Topological structure of the present invention also is suitable for the high-tension dc link transmission (HVDC) in the variable speed generation system.Shown in Figure 10 and Figure 11; Can be as shown in Figure 10 have the high-voltage generator of rectifier (1001) or use the low-voltage generator as shown in Figure 11 and have one or more secondary adapter transformer (1101) and produce direct current output through use, wherein each be secondary by rectification and all such rectifiers connect with series connection or parallel way.Need additional connection device (1002) and protection equipment (1003).

Because topological structure of the present invention; So fixing output frequency of alternating voltage; Thereby allow to be provided with the more small scale of required rectifier and transformer and reduce the flutter component of VD under low wind condition, and then improve the power output quality.

In addition, in case wind turbine begins rotation, although main generator in running, exciter (212) all auxilliary systems of can feeding, thus reduce uninterrupted power supply or HVDC size to a-c transducer.

Though note having described the electrical network application, those skilled in the art will know that the present invention also can be used for other application, such as independent power system or any speed change energy production system.For example, such other speed change energy production system can comprise the power system based on wave and tidal energy, geothermal energy, Application of Solar Energy, water power energy, internal combustion energy etc.

Best power tracking control unit (OPTC)

Best power tracking control unit (OPTC) (303) is that the performed power control circuit adjustment power reference of DFIG controller (300) is so that the control generator power.This benchmark is based on the measuring wind as the main regulation variable.

According to this embodiment, provide a kind of and can in speed range of operation, carry out best power coefficient (C _p) speed change system followed the tracks of.This scope depends on lower velocity limit (ω ₀) and speed limit (ω ₁) and corresponding power lower limit and power upper limit (be respectively P ₀And P ₁).

Fig. 4 illustrates the block diagram of an embodiment of best power tracking control unit (OPTC).The primary input of OPTC is the wind speed of measuring by one or more anemometer (u).In one embodiment, filtering (401) is carried out in this measurement amplified through control system to avoid undesirable frequency, thus the smooth operation signal.

OPTC calculates corresponding performance number (402) for each certain wind speed.This relation by wind turbine, mainly be that the global feature of rotor head is confirmed, and its point is corresponding to maximum pneumatic efficiency.Therefore maximize C _pTo realize maximum power output.The gained performance number is input to power bracket limiter (403).This enforcement comprises major loop.

The auxiliary correction (405) of major loop is applied to income value to improve the C that is optimized _pThe response of following the tracks of.Wind velocity signal according to measurement and filtering calculates (406) double fed induction generators optimum speed.(on the slow-speed shaft) rotor optimum speed is a best tip speed (tip speed) than the product of (λ) and wind speed (u) result divided by rotor plane radius (R).This value multiplied each other with the gearbox ratio calculate the double fed induction generators rotary speed.The gained velocity amplitude is input to velocity interval limiter (407).Output of this part and the pitch correction speed of in pitching speed-adaptive piece (PASB) (410), calculating (PCS) are compared (408).

The rotary speed of luffing angle benchmark, minimum luffing angle and measurement is input to PASB.The luffing angle that (413) be applied to filtering that will gain is provided with point (β _Ref) and minimum luffing angle (β _Min) poor.In order to be coupled, this is initialized as zero, thus β _Ref=β _MinAdd measured rotary speed (ω) to calculate said correction rate.

In the such correction of PASB (408) afterwards, will gain (409) are applied to the gained error, thereby Δ P is provided the power set point to calculate before adding to.

In case proofreaied and correct gained power set point (404), this value be input to power bracket limiter (415) to guarantee that this power reference is at threshold value P ₀And P ₁In.The gained benchmark is power set point (SP_P).

Rotary speed monitoring (417) is applied to this power set point the most at last.Be lower than ω at PCS ₀Situation under (419), will gain or different controllers (420) be applied to such speed difference, thereby provide-Δ P.On the other hand, if PCS is higher than ω ₁(422), the error that then will gain (423) are applied to calculate, thus provide and the proportional Δ P of speed difference at input.

Therefore, in power set point SP_P, this power set point also is input to power bracket limiter (424) so that being provided with of guaranteeing to be calculated a little do not surpass rated power with above-mentioned concrete correct application.Therefore therefore, the output of OPTC is to be passedly to deliver to master controller (302) and be sent to DFIG controller (300) so that the effective power benchmark SP_Pef of control double fed induction generators power.

Because the best power tracking control unit, so improved the power output quality when the alternator speed in alternator speed is equal to, or greater than the rated power appearance.In the prior art variable speed wind turbines with DFIG configuration, though the maintenance of stator power is constant, rotor power also is fed to electrical network through power converter.Because the rotor power pulsations, thus also make the gross power pulsation that is fed in the electrical network, thus influence the power output quality of wind turbine.In the present invention, through using exciter and not being connected to the power converter of electrical network, only the stator through double fed induction generators is delivered to electrical network with power, thereby avoids pulsing and improve the power output quality of wind turbine.

The double fed induction generators controller

The controller of double fed induction generators (300) carries out stator active power and the Reactive Power Control of DFIG.This controller is given well-tuned performance and the control for the gross power of sending to electrical network.As hereinafter specify, the electric parameter of this control through using electrical network flux oriented (GFO) and machine is fully independently based on the different adjustment loop.Measure the gross power that stator (210) that different values to be regulated to control ideally double fed induction generators 205 is sent to electrical network through high accuracy ground, thereby realize high-quality energy.

The controller of double fed induction generators shown in Fig. 5 (300) is controlled and four regulating loops based on electrical network flux oriented (GFO): two current circuits (rotor current loop (509) Irq and rotor current loop (510) Ird) and two loop of power circuit (stator active power loop (505) Ps and stator reactive power loop (506) Qs).

In this exemplary embodiment of the present invention, controller will be through regulating stator active power that rotor current (Av_Ird and Av_Irq) regulates DFIG and reactive power and the therefore adjusting gross power of sending to electrical network.Power controller is through (d q) operates for the electric current of benchmark and voltage value, so the different electric currents that undertaken by system and the voltage measurement rotation (d, q) system that are arrived benchmark by conversion (514,517) with two rotary systems.

In one embodiment, fix the level of magnetization of double fed induction generators (205) through control Av_Ird (is the rotor current of benchmark with ' d ' axle), thereby the reactive power of setting up in the machine flows to.In addition, double fed induction generators (205) inductive-system that can be used as consume reactive power comes work or can be used as the capacitor system that generates reactive power to come work.In this embodiment, with to Av_Irq (with ' q ' axle is the rotor current of benchmark) control carry out control fully independently to Av_Ird.In another embodiment, come to control ideally the active power that generates by double fed induction generators and send to electrical network through control Av_Irq.

Thereby stator power (Av_Ps) is regulated through receiving stator power set point (Sp_Pef) from OPTC (303) and therefore receiving stator power set point (Sp_Ps) from master controller (302) in the stator active power loop (507) of DFIG.This loop can be based on PI controller or the more complicated different controllers of structure.Hereinafter specifically describes the stator active power of DFIG and calculates.PI controller (507) output is that rotor current is provided with point (Sp_Irq).The Av_Irq electric current is a little regulated by this aforementioned setting in Irq rotor current loop (511).This Irq current circuit can be based on PI controller or the more complicated different controllers of structure.Adjuster output is that the Urq rotor voltage is provided with point (Sp_Urq).

In addition, the stator reactive power loop (508) of DFIG is provided with point (Sp_Qs) from master controller (302) reception stator reactive power and regulates stator reactive power (Av_Qs).This Sp_Qs can be provided with based on fixed value, SCADA etc.This reactive power loop can be based on PI controller or the more complicated different controllers of structure.Hereinafter specifically describes the stator reactive power and calculates.PI controller (508) output is that the Ird rotor current is provided with point (Sp_Ird).Av_Ird is a little regulated by this aforementioned setting in Ird rotor current loop (512).This Ird electric current can be based on PI controller or the more complicated different controllers of structure.Adjuster output is that the Urd rotor voltage is provided with point (Sp_Urd).In one embodiment, this method allows from rotor magnetization double fed induction generators, thereby avoids consuming the reactive power from electrical network.In addition, control double fed induction generators level of magnetization and measure electrical network and stator voltage, thus system is all synchronous constantly with electrical network in each moment about amplitude, frequency and the angle of the stator voltage that generated by double fed induction generators (205).Hereinafter will specify to be proofreaied and correct and parting system.

In one embodiment; (two rotary systems of μ-ε) are benchmark to have the anglec of rotation with the measurement (Ir_L1, Ir_L2, Ir_L3) of three rotor currents; Calculate Av_Irq and Av_Ird rotor current; Wherein μ is the electrical network angle that the measurement (Vg_L1, Vg_L2, Vg_L3) (217) according to three line voltages is calculated, and ε is the rotor angle by position and velocity transducer (214) measurement.

Use Id, Iq, Vd, Vq to calculate Av_Ps and Av_Qs:

$\mathrm{Av}\_\mathrm{Ps}=\frac{3}{2}(\mathrm{Vsd}\×\mathrm{Isd}+\mathrm{Vsq}\×\mathrm{Isq})$ Equation 1

$\mathrm{Av}\_\mathrm{Qs}=\frac{3}{2}(\mathrm{Vsq}\×\mathrm{Isq}-\mathrm{Vsd}\×\mathrm{Isd})$ Equation 2

Wherein obtain Vsd, Vsq, Isd, Isq, and these voltage and currents are benchmark with two rotary systems that use anglec of rotation μ through measuring three stator voltages (V_L1, V_L2, V_L3) (216) and three stator currents (I_L1, I_L2, I_L3) (118).

Use the anglec of rotation (μ-ε) two current regulator output Sp_Urd and Sp_Urq are transformed into fixed system, thereby three voltage references that acquisition will apply in the rotor (211) of double fed induction generators (205).Piece 414 shows the conversion of rotor voltage from two rotary systems to the three-phase fixed system.In one embodiment, can use these rotor voltages as being used for the benchmark of generation to the module of the meritorious switch triggering of power electronic converter (222).Piece 415 shows the module that can implement different PWM technology.

According to this embodiment, independently avoided electric parameter to disperse or the influence of theoretical modeling error in power adjustments based on the electronic power control system of two loop of power circuit and two current circuits with the machine electric parameter.The caused error of electric parameter is owing to temperature oscillation due to non-linear or saturation effect changes and avoid through this method.Therefore obtain the good energy of quality and generate, thus the requirement of satisfying and improving various criterion.Regulating only needs different measurements (I_L1, I_L2, I_L3, V_L1, V_L2, V_L3, I_ L1, Ir_L2, Ir_L3, ε, ω).In one embodiment, reactive power is regulated and be independent of the active power adjusting.

The exciter controller

In one exemplary embodiment, speed change system comprises double fed induction generators (205), and its rotor (211) is connected to electronic power converter (222).This electronic power converter is coupled to second electronic power converter (225) through dc bus system (224).In one embodiment, this frequency converter (power converter) (225) is connected to exciter (212) by contactor (228).Exciter such as asynchronous machine, DC generator or synchronous (for example permanent magnetism) machine or reversible electric machine mechanically are coupled to drive chain.

Look spinner velocity and decide, the exciter power demand can flow to just or for negative according to rotor energy.In metasynchronism operation, promptly in the process below synchronizing speed, power flows to the rotor (212) of double fed induction generators (205) from exciter (212), thereby exciter (212) serves as generator.In supersynchronous operation, promptly in the process more than synchronizing speed, power flows to exciter (212) from the rotor (211) of double fed induction generators (205), so exciter (212) serves as motor.Power-balance in the gamut rate process makes the loss in different units in the rotor of double-fed induction machine the power of generation/consumption in the consumption/generation exciter.

In this embodiment of the invention, exciter (212) is regulated by electronic power converter (225) and is controlled by exciter controller (301).Hereinafter is described the control system of exciter (212) as exciter with permanent magnetic motor.It should be apparent to those skilled in the art that and to use dissimilar machines, thereby can correspondingly revise the exciter controller as exciter (212).

Electronic power converter (225) uses dc bus voltage level Av_Ubus to control to/the power that transmits from exciter (212) as the main regulation variable.Fig. 6 has described the embodiment that exciter is regulated.Transducer control unit (200) is fixing can be that variable or static dc bus is provided with point voltage Sp_Ubus (605).Through measuring dc bus voltage, dc bus voltage is provided with a little and is regulated by PI controller (607) or the more complicated different controllers of structure.The active power that this controller foundation will transmit between permanent magnet excitation machine (212) and DC link bus (224) is so that remain in dc bus voltage by the fixing value of transducer control unit (CCU).This active power depends on Sp_IEq.In one embodiment, calculate this Sp_IEq according to following two:

Output+the uncoupling of Sp_IEq=bus voltage regulator (607) and the output equation 3 that switches compensation (608)

Wherein first corresponding to the vibration of possible bus, and the feedforward term of the estimation electric current of second Iz to be representative flow through bus.Might realize the high dynamic power response of permanent magnetic motor by this class formation.In one embodiment, bus current estimates that item does not exist, thereby bus voltage regulator (607) is responsible for generating the required effective Sp_IEq of permanent magnet excitation machine.

In this embodiment, use following Av_IEq to regulate Sp_IEq, the exciter active current that it is benchmark that this Av_IEq has represented with two rotary systems by PI controller (613) or the more complicated different controllers of structure.In one embodiment, can use permanent magnetic motor, thereby need a reduction module can reduce the machine flux and to have better power adjustments at a high speed.In permanent magnetic motor, stator voltage depends on spinner velocity and machine magnetic flux.Thereby, be necessary more than the spinner velocity that the flux through reducing on the machine reduces stator voltage.

Implement a reduction system in one embodiment, the reactive current of needs is provided with a Sp_IEd (618) thereby set up permanent magnet excitation machine (212).In this way, with spinner velocity independently the frequency band range regulating power inner control of electronic power converter (225) with the voltage that permanent magnet generates is set.Use following Av_IEd to regulate Sp_IEd (618), the exciter reactive current that it is benchmark that this Av_IEd has represented with two rotary systems by PI controller (614) or the more complicated different controllers of structure.

In one embodiment, Sp_IEd has fixed the level of magnetization and the voltage level thereof of machine.Sp_IEd has fixed the perhaps required active power of injecting to permanent magnetic motor of permanent magnetic motor.

In one embodiment, can measure two or three exciter phase currents (IExc_L1, IExc_L2, IExc_L3) so that calculate Av_IEd and Av_IEq.Three electric current conversion incipiently (601) become two stationary systems, thereby obtain IE_sx and IE_sy.Secondly, these two electric currents are benchmark (603) with two axle systems that rotate with the permanent magnetic motor total flux, thereby obtain Av_IEd and Av_IEq.Through using according to carrying out this current transformation with lower angle μ Exc, this angle μ Exc obtains according to three that can measure or estimate or two exciter phase voltages (VExc_L1, VExc_L2, VExc_L3).Piece 602 and 604 shows how to obtain permanent magnetic motor flux and absolute value of voltage.

In one embodiment, need effective potentiometer to calculate module (615) because electronic power converter (225) the voltage that will generate must depend in the permanent magnetic motor because of the flux due to the current flowing effect sympathetic.Thereby according to the output of two PI current regulators (613,614) and according to Av_IEd, AV_IEq and | VE| calculates (615) voltage set point Sp_UErd and Sp_UErq.

Use anglec of rotation μ Exc that two voltage set point Sp_UErd are become three stationary systems with Sp_UErq conversion (616).Therefore, voltage reference Sp_UE_rx and the Sp_UE_Ry of acquisition in order in the stator of permanent magnet excitation machine (212), to apply.In one embodiment, can use these voltage set point as being used for the benchmark of generation to the module of the meritorious switch triggering of power electronic converter (225).Piece 617 shows the module that can implement different PWM technology.In one embodiment, dV/dt filter or other any filter (227) can be installed between electronic power converter (225) and exciter (212).

In one embodiment, use exciter (212) can this machine be used for the different units supplying energy to wind turbine as accessory power supply.Disturbance in Power Net or fault do not influence power electronic converter (225).Thereby do not influence the exciter power adjustments.

Dynamic dynamo-electric brake

According to another embodiment, a kind of dynamic dynamo-electric brake (DEB) that allows the wind turbine application dynamo-electric brake with the generation outage machine is provided.Therefore can avoid to cause in the wind turbine components mechanical force of premature damage.

Variable speed wind turbines of the present invention comprises double fed induction generators (205), and its rotor (211) is connected to electronic power converter (222).This electronic power converter (222) is coupled to second electronic power converter (225) through dc bus system (224).This frequency converter (electronic power converter (225)) is connected to exciter (212).Exciter such as asynchronous machine, DC generator, synchronous (for example permanent magnetism) machine or reversible electric machine mechanically are coupled to drive chain.This system also comprises the dynamo-electric brake circuit (231) that is connected to dc bus, such as DC chopper.

In the DFIG of prior art topological structure, if breaking off owing to electric network fault or from electrical network, the stator power of DFIG die-offs, then machine often quickens.Under the situation of wind turbine with the rated power operation, machine possibly lock into hypervelocity.Usually can not use dynamo-electric brake at this moment, because the stator power of DFIG and also have the rotor power of DFIG maybe be low excessively.Yet, because topological structure of the present invention, so exciter power can be used for driving dynamo-electric brake.Under this situation, exciter will be as generator, so power can be sent to different current bus from exciter.Like this, the part electrical power is discharged in the rheostat of the chopper that is connected to dc bus, thereby avoids the hypervelocity of generator.Under such mode, the wind turbine braking does not depend on mechanical brake uniquely.In one embodiment, dynamo-electric brake can use with mechanical brake, thereby allows wind turbine to brake, make mechanical force, peak torque load and undesirable acceleration minimum progressively.For example, dynamo-electric brake can be used and control can be obtained turbine until machinery or pneumatic braking device.

In addition, exciter and DFIG rotor circuit can be used with as coming work in order to the dynamo-electric brake that stops or slowing down the rotation of generator with the serial of dynamo-electric brake circuit.Under these circumstances, realize braking as follows: when brake activated, rheostat was connected, and electrical power flow is to rheostat.Said electrical power can flow from the rotor circuit of DFIG and/or from exciter according to rotor circuit and the exciter power capability separately of DFIG.This process does not also rely on metasynchronism or supersynchronous operator scheme.

Although need whole braking power in supersynchronous operator scheme, wind turbine only need lack the part braking power in the metasynchronism pattern with low velocity work.

Dynamically the Another Application of dynamo-electric brake is when under high wind speed, operating.If when machine is operated near maximal rate, fitful wind occurs, then be necessary to make machine brake to avoid owing to hypervelocity stops.

In the DFIG of prior art topological structure, might increase to be modified to until the pitching of blade and slow down wind turbine from the power output of stator.This operating system has reduced the quality of power output owing to the caused peak value of fitful wind.

Because topological structure of the present invention, so it is constant in the dynamic dynamo-electric brake of activation, to keep the stator power output; Like this, power output keeps high-quality and speed reduction to obtain the control to wind turbine until the pitching by blade.Owing to can use very fast mode to control the power of dynamic dynamo-electric brake, so can carry out accurate control in order to avoid exceeding the speed limit.

As a result, because exciter (212), so braking power is always available.Look the rheostat value of exciter power, exciter converter power and chopper and decide, in one embodiment, braking power can reach generator rated power 30%.

Therefore maximum brake power (P is also arranged _{B_MAX}) available constantly:

P _{B_MAX}=(V _{DC_bus}) ²/ R _BrakeEquation 4

V wherein _{DC_bus}Be dc bus voltage (Av_U _Bus) actual value.

Can come control brake power with the mode that when low velocity is worked, only need lack the part braking power when wind turbine.Yet, all brake available horsepower if wind turbine generator more than normal speed, has necessary use.Therefore, mainly calculate braking power point (SP_P is set according to measurement to wind speed and alternator speed _b).

In order to control necessary braking power exactly, calculate modulation factor (f _MOD).This modulation factor is applied to the maximum brake power (P that can use in each moment _{B_MAX}) to obtain SP_Pb.

SP_P _b=P _{B_MAX}F _MODEquation 5

f _MOD=SP_P _b(R _Brake/ (Av_U _Bus) ²) equation 6

Modulation factor allows the accurate control to braking power.Might use progressive electrodynamic braking.For example when wind turbine promptly stops, needing whole braking power at the beginning.In case activate mechanical braking such as pitching blade, just might reduce electrodynamic braking progressively.

In this exemplary embodiment, dynamically dynamo-electric brake comprises the rheostat that activated by electronically controlled switch (for example IGBT) (resistor, resistor collection or no matter any dispersion unit).Also can use the inverse parallel diode.DEB strictly is not limited to the embodiment that has described.Therefore, the braking chopper can comprise the unit different with said units.

Can activate dynamic dynamo-electric brake in response to various operating parameters.In one embodiment, the speed of axle 213 or turbine wheel shaft (202) can be used for activating braking.This speed can be confirmed and can be used for when surpassing threshold value, activating braking by position and velocity transducer (214).In addition, acceleration or speed can be used as activator appliance with respect to the velocity variations of time.Under this situation, speed can be measured with any unusual acceleration of sensing by position and velocity transducer (214) over time.If acceleration surpasses threshold value, then can activate braking then.In addition, the many different braking condition of design in this exemplary embodiment.Thereby, can depend on the various braking conditions that the rate of change with rate of change, exciter voltage or the exciter voltage of exciter shaft speed, exciter shaft acceleration, DFIG spinner velocity, DFIG acceleration, DFIG rotor frequency and sequence, DFIG rotor frequency rate of change and sequence, exciter frequency, exciter frequency is the basis to the activation of dynamo-electric brake.

Operand power, electric current and voltage also can be used for activating dynamic dynamo-electric brake.For example, if the electric current of rotor (211) electric current or exciter (212) surpasses threshold value, then can activate braking.Similarly, the voltage of rotor (211) and exciter (212) also can be represented certain operation exception.If detect so unusually, then can activate braking.Therefore,, the electric current of rotor (211) or exciter (212) and voltage can activate brake when surpassing threshold value.Similarly, the frequency of the electric current of exciter (212) or rotor (211) and voltage since they can represent hypervelocity or other a certain kind equipment fault and also can be used for activating brake.

Thereby it is following to use method shown in Figure 12 to activate dynamo-electric brake.Sensing braking condition (operation 1200) at first.Estimate this braking condition then to confirm whether it surpasses threshold value, for example need a certain threshold value of brake application to do comparison (operation 1201) with expressing possibility the excessive rate of change of overcurrent, hypervelocity, overvoltage or electric current, speed or voltage.In operation 1202, calculate braking power based on braking condition and the threshold value that is surpassed.After calculating braking power, can activate dynamic dynamo-electric brake (operation 1203).In operation 1204, come the power of self-activating dynamic brake to discharge in dispersion unit.

With regard to the unusual or big acceleration that detects generator, voltage and current can be used for representing unusual acceleration with respect to change of time and these parameters frequency change in time.Therefore, if detect such acceleration, then can activate braking.

Connect (enabling) sequence

According to another embodiment catenation sequence is provided.This embodiment comprises the double fed induction generators (DFIG) (205) that is coupled to exciter (212) and does not have power electronic converter to be connected to electrical network and comprise permission that double fed induction generators is connected to the catenation sequence of electrical network and do not have the consumption of quadergy also not pass through the connection current peak of contactor (215), therefore increases the life-span of contactor (215).Fig. 7 shows catenation sequence.Those skilled in the art if main circuit breaker or any other switch rather than contactor are used for generator is coupled to electrical network, then also can use technology described herein with clear.

In the normal manipulation mode process, turbine utilizes deflection (yaw) motor directed with the wind constantly.When the mean wind speed of measuring during greater than threshold value (be 2.5 meters of per seconds in one embodiment), if satisfy all the other required conditions, then blade pass is crossed pitch motor and is moved to the position that the permission main rotor begins to rotate.

In one embodiment, before the beginning catenation sequence, must satisfy initial condition (701).These conditions relate to the state of spinner velocity, rotor contactor (228) and in order to begin any other condition in advance of this sequence.In one embodiment, in case satisfy these conditions, spinner velocity just must rise to N1 (in one embodiment, with regard to the synchronizing speed DFIG of 1800rpm/60Hz, the value of N1 can be 1170rpm).In case reach this spinner velocity, the electronic power converter (225) that just activates exciter side is so that regulate the dc bus voltage level, and this is corresponding to state 702.

In one embodiment; In case dc bus has reached the VBUS1 level; Spinner velocity just must rise to N2＞=N1, and (in one embodiment, with regard to the synchronizing speed DFIG of 1800rpm/60Hz, the value of N2 can be 1260rpm; And with regard to the IGBT of 1700V, the VBUS1 level can be 1050V).The electronic power converter of DFIG side (222) connect (703) then in case through contactor (215) voltage near 0.This realizes in the following manner: with magnitude of voltage, sequence, frequency and other variable aequilateral mode at contactor (215), magnetize double fed induction generators (205) by electronic power converter (222) through rotor (211).When satisfying voltage amplitude, electric voltage frequency, these conditions of level angle/delay and some other conditions, contactor (215) closed (704) and stator current are near 0.Double fed induction generators (205) does not have to consume from the energy of electrical network and avoids the possible disturbance on the electrical network.

In case satisfied this sequence, just activated power control (705).In order to allow smooth connection to arrive electrical network, oblique ascension is provided with a little from the active power of OPTC and comes the reactive power of autonomous controller to be provided with a little in the initial instant process.

In whole catenation sequence processes, if to detect error then recover this sequence and generate the state that the mode of reporting to the police is kept watch on all unit that relate to.Visual alarm type and deciding, this sequence begin after can be at the fixed time, if perhaps this error is important, then in wind turbine, activate a kind of emergency mode, and this intervention that needs the people is to withdraw from this pattern.

In Fig. 9, described in state 703 processes and be used for synchronous control system.The execution stator voltage is regulated.Stator voltage and line voltage are to the input of stator voltage adjuster (903 and 904), and the output of this adjuster is at axle d rotor electric current part a little to be set.Add output to the proportional electric current item of the magnetizing current of generator as the voltage regulator of feed forward element.According to the mains frequency of the line voltage of measuring, measurement and depend on that the K constant of the electric parameter of generator calculates such current feed-forward.Utilize the interpolation of this feedforward term in piece 905 to come the acceleration synchronization process.As two sums of the output of piece 905 is that rotor current in " d " axle is provided with a little.In whole synchronizing processes, the rotor current in " q " axle is provided with and a little equals 0.It is to the input of Current Regulation piece (906) that two electric currents are provided with point (in " d " axle and " q " axle), wherein controls them by pi regulator.In piece 907, calculate the angle that is used for two axle systems (" d " and " q ") being converted to 3 phase systems at piece 906 based on electrical network angle and mechanical angle.

Break off (stopping using) sequence

Break sequence is provided according to another embodiment of the present invention.This embodiment comprise the double fed induction generators (DFIG) (205) that is coupled to exciter (212) and do not have power electronic converter to be connected to electrical network and comprise break sequence that permission is broken off double fed induction generators (205) from electrical network and not with overcurrent or the relevant any disturbance of overvoltage on the different units of system.Because the electric current near 0 breaks off contactor (215), so increase the life-span of this contactor and reduce attended operation.It also allows contactor with regard to same application, to compare lower rated value with other break sequence.

In the normal running of wind turbine; Usually owing to the disappearance of wind condition is reached this sequence, but also can artificially ask, the fault in any subsystem of remote supervisory control and data acquisition (SCADA) request, wind turbine perhaps reaches this sequence under the situation of any other reason in excessive wind-force, this locality.

In one embodiment, must reduce stator power and stator current obliquely so that in the stator of generator, there is not electric current (710).Optimize the oblique deascension time according to the reason of break sequence request.In order in wind turbine, to avoid unnecessary mechanical stress, the oblique deascension time is the maximum that allows the wind turbine safety operation.Self-evident, oblique deascension time requirement is not all identical for each situation.

In case satisfied this state (710), just break off main contactor (215), thereby reach (711) state.Because meritorious the setting with reactive power is 0 breaking off contactor (215) before a little; But DFIG stator electrical network connects does not have electric current so DFIG controller (300) injects magnetizing current; Thereby realizing the disconnection of contactor near 0 electric current, thereby prolong the life-span of contactor (115).

Inactive rotor electronic power converter (222) when satisfying state (711), this is corresponding to state (712).When inactive rotor electronic power converter, the energy of in the inductive circuit of double fed induction generators, storing is sent to DC link.

Pitch control subsystem device (EBPC) based on exciter

In this embodiment of the invention, variable speed wind turbines comprises the pitch control subsystem device (EBPC) based on exciter.Fig. 8 has described an exemplary embodiment of this type of pitch control system that is the basis with restriction exciter power demand.

The main value of pitch control system is the power of exciter.Set up exciter power-handling capability (801).Exciter Power Limitation adjuster (804) fixes leaf position based on this benchmark according to exciter power actual value (802) point (Sp_ β) is set.In one embodiment, when the output of the power of wind turbine remains on rated power when following, in a single day Sp_ β will get the small value (for example between 0 ° and 2 °), and reach rated power, and Sp_ β will increase so that limit exciter power.

In one embodiment, the output of 804 blade pitch position is regulated by PI positioner (806) or the more complicated different controllers of enforcement.Error to the input of PI positioner is:

Error_ β=Sp_ β-Av_ β equation 7

Av_ β is the leaf position actual value of being measured by position and velocity transducer (214).Position control output is that luffing speed is provided with point (Sp_n).Blade will move the position of being asked to arrive with such speed.

In one embodiment, the output of 806 luffing speed is saved by PI speed control (808) or the more complicated different controllers of enforcement.Error to the input of PI speed control is:

Error_n=Sp_n-Av_n equation 8

Av_n is the actual value by the blade velocity of velocity transducer (214) measurement.The output of speed regulator is DC motor (305) speed (Sp_n) of asking in order to reach and the electric current that needs is provided with a little.

In one embodiment, the output of 808 electric current is regulated by PI current controller (810) or the more complicated different controllers of enforcement.Error to the input of PI current controller is:

Error_I=Sp_I-AV_I equation 9

AV_I is the actual value by the DC motor electric current of current sensor (812) measurement.The output of current controller is the reference voltage that will in DC motor, apply.In one embodiment, these reference voltages can be created through different PWM technology, thereby trigger the meritorious switch of power electronic converter (811).

In one embodiment, in case of emergency, pitch motor drives and switches to Emergency Power (EPS) from EBPC.Therefore, drive electric motor is directly fed till reaching east-west transverse position (feathered position) (near 90 °) by EPS (816) through urgent relay (717).The end of the electric current that leaf position switch (818) decision EPS provides.

In one embodiment, the driving in order to moving blade is a DC motor.Those skilled in the art will know also can use AC inductance motor and autosynchronous motor.

In one embodiment, the driving in order to moving blade can be the pitching exciter that waterpower, the servo valve by integrated functionality (807,808,809,810,811) pneumatic or other type are controlled.

Anti-wear and the lubricating system (CAWLS) of current-collector

In another embodiment of the present invention, variable speed wind turbines comprises the pitch control system that is the basis with restriction exciter power demand.

Use DC motor as the situation that is used for the driving that pitching moves under, the anti-wear and lubricating system (CAWLS) of application sets electrical equipment is to avoid the further ill-effect that fixedly pitch position was caused for a long time.For example, can avoid causing through same position the too early wearing and tearing of the current-collector and the brush of DC motor owing to electric current.Improve the lubricated of blade bearing in addition significantly.

Therefore, implement CAWLS to avoid current-collector and the too early wearing and tearing of brush and lubricating of improvement blade bearing as the DC motor of pitching driving.In one embodiment, this system is based on that the mode that moves constantly around the desired location with luffing angle is introduced non-significantly additional position or speed is provided with a little.Depend on that according to wherein amplitude and frequency the sinusoidal wave benchmark of different parameters arranges luffing angle and change.Especially should include the natural frequency of wind turbine in consideration with tired consideration item and come assigned frequency.In one embodiment, for example with one minute cycle and 0.2 ° amplitude design of sine ripple benchmark.It should be apparent to those skilled in the art that no matter any other waveform can be used cycle or amplitude.CAWLS implements not influence fully wind turbine and produces power, but it is avoided the wearing and tearing of current-collector and brush really and improves their cooling and fat liquoring.CAWLS also improves the lubricated of blade bearing.

In addition, this system can be used for improving the lubricated of blade bearing in any pitching drives, thereby increases the life-span of these parts.

Therefore, a kind of variable speed wind turbines that has double fed induction generators, exciter and be not connected to the middle power transducer of electrical network is disclosed.The present invention has also described power control and pitch regulation.

Wind power generation increases in the whole world considerablely.Even this industry has risen to ripe level with technology in this field, but estimates at large that still this growth will continue following many decades.Total radix of the wind capacity of installing along with the wind energy turbine set increase in size continues to increase, and the importance that improves the power output quality becomes vital challenge.

Many novel parts in above-mentioned exemplary embodiment of the present invention, have been introduced.In power system, comprise exciter, wherein power converter is isolated (not being connected to electrical network) from electrical network.Therefore, the present invention is directed to the total problem of the caused majority of variable speed wind turbines that connects electrical network and solution is provided as in the power of sending, having harmonic distortion, flicker and pulsation.Therefore improve the power output quality significantly.In these embodiment, power controlling output exactly keeps constant in addition more than normal speed, thereby keeps away that rabbit depends on wind speed and the power fluctuation that changes.In fact, exemplary embodiment provides a kind of close friend's connection and disconnect method from the reactive power of electrical network of avoiding consuming.In addition, generate Disturbance in Power Net according to the power of the embodiment of the invention such as electric network fault is less sensitive and in independent light current net, more best performance is provided.Therefore, increase the wind capacity of scale and installation through allowing wind energy turbine set, thereby satisfy the requirement of different regulations and improve the power output quality, system shown in the exemplary embodiment is especially attractive for emerging wind power station.

In addition; Exemplary embodiment can comprise some other benefits, such as: under the situation of permanent magnetic motor, use exciter as accessory power supply, might generate by low voltage power converter in voltage power and need not power transformer, simplify electric component and when the DC motor type is used for the pitching blade, prevent the current-collector wearing and tearing of this type of motor and improve blade bearing and lubricate.

The alternate embodiment of wind turbine system shown in Fig. 2 also is possible.For example, exciter (212) can connect or be positioned over the interior any position of drive chain of wind turbine.The additional embodiments that comprises two or more exciters also is feasible.

To be clear that a kind of novelty and the favourable variable speed wind turbines of the invention provides described herein according to above description.Yet must be clear is to will be understood that aforementioned specific descriptions are to illustrate in the heart.Here the details that provides is not intended to limit scope of the present invention with explanation.In addition, can carry out many modifications and adaptation and can substitute method and the enforcement of describing and illustrating here with equivalent method.Thereby can use other different modes embodiment of the present invention and do not break away from essence of the present invention and scope, and understanding the invention is not restricted to the embodiments described herein.

Claims (21)

1. variable speed wind turbines comprises:

The rotor that comprises at least one blade;

Be coupled to the drive chain of said rotor, said drive chain comprises double fed induction generators DFIG at least, and said DFIG has the stator that can be connected to power grid at least;

Be coupled to an exciter of said drive chain; And

At least one power converter, and said electrical network is isolated and the rotor and the said exciter that are electrically coupled to said double fed induction generators between said rotor and said exciter, to transmit electrical power; And

The electrodynamic braking circuit is positioned in the said power converter between said rotor and the said exciter.

2. variable speed wind turbines according to claim 1, wherein said electrodynamic braking circuit are connected to the direct current DC bus in the said power converter.

3. variable speed wind turbines according to claim 2, wherein said power converter comprise first electronic power converter and second electronic power converter,

Wherein said dc bus is coupled to said second electronic power converter with said first electronic power converter,

Wherein said first electronic power converter is connected to said double fed induction generators, and said second electronic power converter is connected to said exciter.

4. variable speed wind turbines according to claim 1, wherein said electrodynamic braking circuit dissipate from least one power in the rotor circuit of said exciter and said DFIG.

5. variable speed wind turbines according to claim 1, wherein said electrodynamic braking circuit comprise the dispersion unit that is activated by controllable switch device at least.

6. variable speed wind turbines according to claim 5, wherein said dispersion unit is a resistor.

7. variable speed wind turbines according to claim 1, if wherein activate electrodynamic braking, then said electrodynamic braking circuit dissipates from least one power in the rotor circuit of said exciter and said DFIG.

8. variable speed wind turbines according to claim 1 wherein activates said electrodynamic braking circuit in response in sensing double fed induction generators axle speed and the double fed induction generators axle acceleration at least one.

9. variable speed wind turbines according to claim 7 wherein activates said electrodynamic braking circuit in response in sensing exciter shaft speed and the exciter shaft acceleration at least one.

10. variable speed wind turbines according to claim 7 wherein activates said electrodynamic braking circuit in response in sensing DFIG spinner velocity and the DFIG rotor acceleration at least one.

11. variable speed wind turbines according to claim 7 wherein activates said electrodynamic braking circuit in response in sensing DFIG rotor frequency and sequence and DFIG rotor frequency rate of change and the sequence at least one.

12. variable speed wind turbines according to claim 7 wherein activates said electrodynamic braking circuit in response in sensing exciter frequency and the exciter frequency change rate at least one.

13. variable speed wind turbines according to claim 7 wherein activates said electrodynamic braking circuit in response in sensing exciter voltage and the exciter voltage rate of change at least one.

14. a variable speed wind turbines system comprises:

The first rotor axle that comprises at least one blade;

Double fed induction generators is coupled to said the first rotor axle and has the stator that is connected to power grid and have axle;

Exciter is coupled to the axle of said double fed induction generators;

Power conversion system, isolate with said electrical network and the rotor and the said exciter that are electrically connected to said double fed induction generators to control said double fed induction generators; And

Electrical braking device is used for making the axle of said double fed induction generators and at least one braking of said the first rotor axle.

15. one kind is used for the method that use electrodynamic braking circuit is braked in any described variable speed wind turbines according to claim 1-13, said method comprises:

Sensing is used to activate the braking condition of said electrodynamic braking circuit;

Whether the braking condition of confirming said sensing surpasses threshold value; And

Surpass said threshold value and activate said electrodynamic braking circuit and discharge to dispersion unit in response to the braking condition of said sensing with the braking power of at least one in the rotor of future self-excitation machine and double fed induction generators DFIG.

16. method according to claim 15 also comprises:

Braking condition based on said sensing calculates said braking power to be discharged.

17. method according to claim 16, wherein said braking power is perhaps discharged under the supersynchronous operator scheme in the metasynchronism of said DFIG.

18. method according to claim 16, the said braking power of wherein discharging to said dispersion unit flows from the rotor circuit of said DFIG and the said exciter at least one based on the rotor circuit of said DFIG and said exciter power capability separately.

19. the method that is used to brake according to claim 16, wherein power exhausts in the rheostat of chopper circuit.

20. the method that is used to brake according to claim 16 also comprises:

Come the sensing braking condition based in generator or exciter speed, generator or exciter acceleration, wind speed, generator or exciter voltage, generator or exciter electric current and generator or the exciter frequency at least one;

Wherein control dissipation power in response in said generator or exciter speed, generator or exciter acceleration, wind speed, generator or exciter voltage, generator or exciter electric current and generator or the exciter frequency at least one.

21. the method that is used to brake according to claim 15, the power response that wherein transmits to dc bus exhausts in the electrodynamic braking circuit in the braking condition of said sensing.

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