CN102570852A - Main circuit of wind power converter - Google Patents

Abstract

The invention discloses a circuit structure of a wind power converter. The circuit structure comprises a six-phase uncontrolled rectifier circuit connected with a generator and used for rectifying and outputting a direct current voltage, a rectifying output capacitor bank, a quadruple boosting conversion circuit used for four-times boosting conversion of the direct current voltage and enabling a bus voltage to be stable, a braking unit used for absorbing the energy of the generator to protect a converter device when a power grid fails or a fan exceeds the speed, and a triplex grid-connected inverter circuit used for performing triplex alternating current conversion on the direct current bus voltage to output an alternating current voltage, wherein the six-phase uncontrolled rectifier circuit, the rectifying output capacitor bank, the quadruple boosting conversion circuit, the braking unit and the triplex grid-connected inverter circuit are sequentially connected. According to the scheme, the circuit structure of the wind power converter is compact and general in structure, flexible in control and stable in operation.

Description

A kind of wind electric converter main circuit

[technical field]

The present invention relates to a kind of wind power generation field, particularly the wind electric converter main circuit in the wind power generation.

[background technology]

Along with the power of wind-powered electricity generation unit continues to increase, present main flow has been the wind-powered electricity generation unit of 1.5MW, and the America and Europe has been the wind-powered electricity generation unit of 3MW; In order to improve the utilization ratio of wind-powered electricity generation; The power of wind-powered electricity generation unit also will continue to increase, and the wind-force generating converter indispensable energy conversion link that is wind turbine generator, because size, the direction of nature apoplexy have very big randomness; Cause the wind-driven generator rotating speed sometimes fast and sometimes slow, voltage magnitude that sends and frequency are also disorderly and unsystematic.The main effect of wind-force generating converter is exactly to convert the electric voltage frequency of wind-driven generator, the amplitude indefinite electric energy that floats into frequency, amplitude stability, meet the electric energy of electrical network requirement, and the present invention invents design with regard to being based on this.

[summary of the invention]

The present invention has overcome the deficiency of above-mentioned technology, and a kind of compact conformation is provided, and control is flexible, stable wind electric converter main circuit scheme.

For realizing above-mentioned purpose, the present invention has adopted following technical proposal:

A kind of wind electric converter main circuit; Include the six phase controlled rectifier circuit 1 not that is used for being connected the rectification output dc voltage with generator; Rectification output capacitor group 2; Be used for direct voltage is carried out four boosting inverters and makes the stable quadruple boost conversion circuit 3 of busbar voltage; Be used for when electric network fault or blower fan hypervelocity, absorbing the brake unit 4 of generating pusher side protecting energy current transformer device; And the triple combining inverter circuit 5 that are used for DC bus-bar voltage is carried out triple interchange conversion output AC voltages, said six phase not controlled rectifier circuit 1, rectification output capacitor group 2, quadruple boost conversion circuit 3, brake unit 4, triple combining inverter circuit 5 is connection in order.

Described six phase not controlled rectifier circuit 1 includes generator output switch 11; And be used for becoming the ac voltage rectifier of generator output the six phase of direct voltage not control rectifier bridge 12; Said generator output switch 11, six phase are not controlled rectifier bridge 12 for connecting in order; Said six phase is not controlled rectifier bridge 12 and is comprised 6 parallel connections rectifier diode group 121 together, and said each rectifier diode group 121 comprises two end to end rectifier diodes.

Described quadruple BOOST boost conversion circuit 3 comprises four BOOST boost conversion circuits 31 that are connected in parallel; Said each BOOST boost conversion circuit 31 includes the filter reactor group 311 that is used for the filtering high frequency waves and lets direct current and low-frequency current pass through; Be used to improve DC bus-bar voltage and stable BOOST circuit module 312, said filter reactor group 311, BOOST circuit module 312 are connection in order.

Described brake unit 4 comprises three brake unit modules 41 that are connected in parallel; Said each brake unit module 41 includes and is used for the used up brake resistance of the excess energy of DC circuit 411, is used to control the braking circuit module 412 of conducting of this unit module and shutoff, and said brake resistance 411, braking circuit module 412 are to connect in order.

Described triple combining inverter circuit 5 comprises three combining inverter circuit 51 that are connected in parallel; Said each combining inverter circuit 51 includes the inverter circuit module 511 that is used for direct current is converted to three-phase alternating current; Inversion output switch 512; Inversion filter reactor group 513; And the inversion filtering capacitor group 514 that is used to limit the low three-phase alternating current of high order harmonic component and output harmonic wave content, said inverter circuit module 511, inversion output switch 512, inversion filter reactor group 513, inversion filtering capacitor group 514 are connection in order.

The invention has the beneficial effects as follows: 1, through increasing stable this link of voltage source inverter type topological structure of dc voltage; Thereby solved the stable inverter that makes that guarantees DC bus-bar voltage when the less generator output voltage of wind-force is low and kept good operation characteristic; It improves the inverter DC bus-bar voltage through the link of boosting and is stabilized in suitable scope; Make the modulation depth scope of inverter good, improve operational efficiency, reduce loss; Circuit can also carry out power factor correction to the magneto alternator outlet side simultaneously, changes the duty ratio of switching device, makes the generator output current keep sinusoidal and also keeps synchronous with output voltage.2, whole system through increase booster circuit with the DC input voitage grade improve, system's control is simple, control method flexibly, the switching device utilance is high, inverter has stabilized input voltage, inversion is effective, harmonic content is low, the advantage of good economy performance is in practical application.3, satisfy half direct-drive type, direct drive type wind generating demands of applications, can also be extended to the more application of high-power wind-driven generator group such as following 4MW, 5MW, 6MW.

[description of drawings]

Fig. 1 is a block diagram of the present invention.

Fig. 2 is the not connecting circuit figure of controlled rectifier circuit and rectification output capacitor group of six phase of the present invention.

Fig. 3 is the connecting circuit figure of quadruple boost conversion circuit of the present invention and brake unit.

Fig. 4 is a combining inverter circuit figure in triple combining inverter circuit of the present invention.

[embodiment]

Be described in further detail below in conjunction with accompanying drawing and execution mode of the present invention:

Shown in Fig. 1-4; A kind of wind electric converter main circuit; Include in order not controlled rectifier circuit 1 of being used for of connecting be connected the rectification output dc voltage with generator six phase; Rectification output capacitor group 2; Be used for direct voltage is carried out four boosting inverters and makes busbar voltage be stabilized in the quadruple boost conversion circuit 3 of OK range, be used for when electric network fault or blower fan hypervelocity, absorbing generating pusher side protecting energy current transformer device and realize that low-voltage passes through the brake unit 4 of function, and be used for DC bus-bar voltage is carried out triple combining inverter circuit 5 that the alternating voltage of electrical network connection request is satisfied in triple interchanges conversions and output.

Said six phase not controlled rectifier circuit 1 comprises that the generator that connects is in order exported switch 11 and six phase is not controlled rectifier bridge 12; Said six phase is not controlled rectifier bridge 12 and is comprised 6 parallel connections rectifier diode group 121 together; Said each rectifier diode group 121 comprises two end to end rectifier diodes, and the tie point of said two end to end rectifier diodes is as the input of rectifier diode group 121, two disconnected rectification output ends as rectifier diode group 121 of said two rectifier diodes; Said six phase is not connected with rectification output capacitor group 2 after not controlling the bigger electric current of rectifier bridge 12 output harmonic wave content; Owing to do not control the nonlinear characteristic of rectifier bridge, the distortion of rectifier bridge input side current characteristics is very serious, and harmonic content is bigger; The generator power factor is reduced, and generator torque vibrates.Can pass through power factor correction technology, change the duty ratio of switching device, make the generator output current keep sinusoidal and also keep synchronous with output voltage.

Said rectification output capacitor group 2, the stability through capacitor group raising DC bus-bar voltage is connected with quadruple BOOST boost conversion circuit 3 then.

Described quadruple BOOST boost conversion circuit 3 comprises four BOOST boost conversion circuits 31 that are connected in parallel; Said each BOOST boost conversion circuit 31 include in order connect being used for the filtering high frequency waves and let filter reactor group 311 that the electric current of direct current and low frequency passes through, be used to the BOOST circuit module 312 that improves DC bus-bar voltage and be stabilized in OK range; Pass through to insert filter inductor from the electric current of rectification output capacitor group 2 outputs; Be connected with BOOST circuit module 312 afterwards; Through the DC/DCBOOST link of boosting; Obtain the stable voltage source inverter type topological structure of dc voltage, can solve and guarantee the stable of DC bus-bar voltage when the less generator output voltage of wind-force hangs down, thereby make inverter keep good operation characteristic.It improves the inverter DC bus-bar voltage through the link of boosting and is stabilized in suitable scope; Make the modulation depth scope of inverter good, improve operational efficiency, reduce loss, circuit can also carry out power factor correction to the magneto alternator outlet side simultaneously.

Can find out, whole system through increase quadruple boost converter circuit 3 with the DC input voitage grade improve, system's control is simple, control method flexibly, the switching device utilance is high, inverter has stabilized input voltage, inversion is effective, harmonic content is low, the advantage of good economy performance is in practical application.

Described brake unit 4 comprises three brake unit modules 41 that are connected in parallel; Said each brake unit module 41 include in order being used for of connecting the used up brake resistance of the excess energy of DC circuit 411, be used to control the braking circuit module 412 of conducting of this unit module and shutoff; DC bus-bar voltage continues to raise in frequency converter; When direct voltage reached the cut-in voltage of brake unit 4, braking circuit module 412 power switch pipes were open-minded, and electric current flows through brake resistance 411; Brake resistance 411 release heat, frequency changer direct current bus voltage reduces; When DC bus-bar voltage dropped to brake unit 4 and stops voltage, braking circuit module 412 power tubes turn-offed.Do not have stalling current to flow through resistance this moment, and brake resistance 411 reduces self temperature at natural heat dissipation; When the voltage of dc bus raises when making brake unit 4 actions again, brake unit 4 will repeat above process, and the balance busbar voltage is normally moved system.

Described triple combining inverter circuit 5 comprises three combining inverter circuit 51 that are connected in parallel; Said each combining inverter circuit 51 includes the inverter circuit module 511 that direct current is converted to three-phase alternating current that connects in order; Inversion output switch 512; Inversion filter reactor group 513 and being used to limits the inversion filtering capacitor group 514 of the low three-phase alternating current of high order harmonic component and output harmonic wave content, and it is connected with external circuit said inversion filtering capacitor group 514 as the output of triple combining inverter circuit 5.

BOOST circuit module 312 in the present embodiment, braking circuit module 412, inverter circuit module 511 all adopt similar circuit configuration; It is connected with the equalizing capacitance resistance circuit after all mainly being connected in series by two IGBT modules again; Wherein in BOOST circuit module 312 and braking circuit module 412; The tie point of two IGBT modules is as input, and the tie point of two IGBT modules is brought in usefulness as output in inverter circuit module 511.

Following each parameter setting of present embodiment mainly is used in the 3MW wind electric converter system; Said quadruple boost converter circuit 4 adopts quadruple BOOST technology; The specified voltage that is input into of transformer is 620V owing to be incorporated into the power networks; Then: the sine wave filter output voltage also should be 620V; This moment, crest voltage was:

but need to consider the loss of voltage on the sine wave filter, therefore select Vdc=1100V here.

When generator output voltage was up to 681V, the duty ratio of switching tube is minimum in the Boost converter was about: $D\mathrm{Min}=\frac{\mathrm{Vdc}-\mathrm{Vd}}{\mathrm{Vdc}}=\frac{1100-947}{1100}=13.9\%.$ When generator output voltage is minimum when reaching 323V, the duty ratio of switching tube is the highest in the Boost converter, is about: $D\mathrm{Max}=\frac{\mathrm{Vdc}-\mathrm{Vd}}{\mathrm{Vdc}}=\frac{1100-449}{1100}=59.2\%.$

When motor speed was the highest, the total output current of Boost converter was no more than

It is divided by the fly-wheel diode in four Boost converters, so the maximum uniform current of fly-wheel diode does

But; Fly-wheel diode carries out work at intermittence under the state, and the on-state rate of its on-state rate and switching tube is closely bound up, at this moment the on-state rate 13.9% of switching tube; The fly-wheel diode on-state rate is 1-139%=86.1%, and the average current in the pulse ON time does each time $I=\frac{909}{86.1\%}=1056A.$

When motor speed is minimum; The total output current of Boost converter is no more than

three fly-wheel diodes divide back for

this moment switching tube on-state rate 59.2%; The fly-wheel diode on-state rate is 1-59.2%=40.8%, and the uniform current in the pulse ON time is each time

What said quadruple booster converter 4 adopted is quadruple boost chopper principle, and the purpose of quadrupleization is shunting and reduces the harmonic content in the electric current, improves electric pressure and be stabilized in suitable scope, improves the stable of DC bus-bar voltage.

Said triple combining inverter circuit 5 adopts triple modular redundant PWM inverter; The form that is used for the DC side energy conversion is become to satisfy the electrical network connection request passes to electrical network; When keeping dc voltage constant, make the AC side phase current approach sine, phase current and phase voltage homophase; Power factor approaches 1, is transported to the harmonic wave and the idle content of electrical network with minimizing.It is to realize the parallel current-sharing of circuit that this inverter adopts the purpose one of triple modular redundant, improves power grade, the 2nd, reduce the harmonic content in the ac output current, and satisfy the requirement of electrical network to harmonic wave.Triple inverter gross outputs are:

$S=\sqrt{3}\mathrm{Vo}*\mathrm{Io}=\sqrt{3}\×620V\×3000A=3.3\mathrm{MW}$

V0 is the line voltage that is connected to electrical network in the following formula, and I0 is the output current phase effective value of inverter.In each heavy inverter, the phase current peak current of IGBT adds 20% allowance and can get Itm and be:

$\mathrm{Itm}=\frac{\sqrt{2}\mathrm{Io}}{0.8}=\frac{\sqrt{2}\×1000}{0.8}=1767.5A$

The line voltagerating voltage of combining inverter is 620V, and the peak value that can calculate phase voltage is 506V, and according to the requirement of inversion, dc voltage generally is higher than the phase voltage rated value, can get the minimum 877V of direct voltage.Therefore setting the DC side rated voltage is 1100V.

Therefore used insulated gate bipolar transistor is that the adoptable model of IGBT module is SKIIP2403GB172 in the triple modular redundant PWM inverter, and its grade is 1700V/2400A.

Claims (5)

1. wind electric converter main circuit; It is characterized in that including the six phase controlled rectifier circuit (1) not that is used for being connected the rectification output dc voltage with generator; Rectification output capacitor group (2); Be used for direct voltage is carried out four boosting inverters and makes the stable quadruple boost conversion circuit (3) of busbar voltage; Be used for when electric network fault or blower fan hypervelocity, absorbing the brake unit (4) of generating pusher side protecting energy current transformer device; And the triple combining inverter circuit (5) that are used for DC bus-bar voltage is carried out triple interchange conversion output AC voltages, said six phase not controlled rectifier circuit (1), rectification output capacitor group (2), quadruple boost conversion circuit (3), brake unit (4), triple combining inverter circuit (5) is connection in order.

2. a kind of wind electric converter main circuit according to claim 1; It is characterized in that described six phase not controlled rectifier circuit (1) include generator output switch (11); And be used for becoming the ac voltage rectifier of generator output the six phase of direct voltage not control rectifier bridge (12); Said generator output switch (11), six phase are not controlled rectifier bridge (12) for connecting in order; Said six phase is not controlled rectifier bridge (12) and is comprised 6 parallel connections rectifier diode group (121) together, and said each rectifier diode group (121) comprises two end to end rectifier diodes.

3. a kind of wind electric converter main circuit according to claim 1; It is characterized in that described quadruple BOOST boost conversion circuit (3) comprises four BOOST boost conversion circuits (31) that are connected in parallel; Said each BOOST boost conversion circuit (31) includes the filter reactor group (311) that is used for the filtering high frequency waves and lets direct current and low-frequency current pass through; Improve also stable BOOST circuit module (312) of DC bus-bar voltage with being used to, said filter reactor group (311), BOOST circuit module (312) are to connect in order.

4. a kind of wind electric converter main circuit according to claim 1; It is characterized in that described brake unit (4) comprises three brake unit modules (41) that are connected in parallel; Said each brake unit module (41) includes the braking circuit module (412) that is used for the used up brake resistance of the excess energy of DC circuit (411), is used to control conducting of this unit module and shutoff, and said brake resistance (411), braking circuit module (412) are for connect in order.

5. a kind of wind electric converter main circuit according to claim 1; It is characterized in that described triple combining inverter circuit (5) comprise three combining inverter circuit (51) that are connected in parallel; Said each combining inverter circuit (51) includes the inverter circuit module (511) that is used for direct current is converted to three-phase alternating current; Inversion output switch (512); Inversion filter reactor group (513); And the inversion filtering capacitor group (514) that is used to limit the low three-phase alternating current of high order harmonic component and output harmonic wave content, said inverter circuit module (511), inversion output switch (512), inversion filter reactor group (513), inversion filtering capacitor group (514) are connection in order.

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