CN204905893U - Double -fed aerogenerator's low voltage ride through system based on control of trouble current -limiting - Google Patents

Abstract

Double -fed aerogenerator's low voltage ride through system based on control of trouble current -limiting, it relates to a double -fed aerogenerator system. The utility model discloses an in order to solve present double -fed aerogenerator system when carrying out low voltage ride through, the electric current changes the range greatly, and the low voltage ride through effect is poor to the problem that is unfavorable for the normal operating of system behind the voltage recover. The utility model discloses a double -fed aerogenerator and trouble current limiter, trouble current limiter are established between equivalent electric wire netting and double -fed aerogenerator stator, and the trouble current limiter includes that rectifier bridge circuit and segmentation switching circuit, rectifier bridge circuit include a bridge arm, second bridge arm and third bridge arm, imitates the mid point that the electric wire netting connect first bridge arm, the midpoint connection double -fed aerogenerator of third bridge arm, and segmentation switching circuit connection is between the mid point of the mid point of first bridge arm and third bridge arm. The utility model discloses has better low voltage ride through performance.

Description

Based on the low voltage ride through system of the double-fed wind power generator that failure current limit controls

Technical field

The utility model relate to double-fed wind power generator system and, be specifically related to the low voltage ride through system of double-fed wind power generator controlled based on failure current limit, belong to double-fed wind power generator technical field.

Background technology

In the last few years, along with country is to the attention further of generation of electricity by new energy technology, wind power generation becomes now very popular new industry.Wind-driven generator has different types of machines available, and double-fed asynchronous formula and permanent magnet direct-driven cross the type being progressively chosen as main flow in Wind Power Development process so far.One of critical problem of current dual-feed asynchronous wind power generator is exactly low voltage crossing technology.Domestic at present what mainly adopt low voltage crossing is that crowbar circuit suppresses, but it can bring a series of shortcoming.By force double-fed wind power generator is become Module of Asynchronous Generator when line voltage is low, absorb idle like this from electrical network, be unfavorable for the recovery of voltage after fault.

Utility model content

The purpose of this utility model is to solve existing double-fed wind power generator system when carrying out low voltage crossing, and curent change amplitude is large, low voltage crossing weak effect, and the problem of the normal operation of system after being unfavorable for voltage resume.

The technical solution of the utility model is: based on the low voltage ride through system of the double-fed wind power generator that failure current limit controls, comprise double-fed wind power generator and low voltage ride through device, described low voltage ride through device comprises fault current limiter, fault current limiter is located between double-fed wind power generator and equivalent electrical network, described fault current limiter comprises rectifier circuit and segmental resection circuit, described rectifier circuit comprises the first brachium pontis, second brachium pontis and the 3rd brachium pontis, equivalence electrical network connects the mid point of the first brachium pontis, the mid point of the 3rd brachium pontis connects double-fed wind power generator, described segmental resection circuit is also connected between the mid point of the first brachium pontis and the mid point of the 3rd brachium pontis.

The number of described fault current limiter is three, is located at respectively on the three-phase output end of equivalent electrical network.Although bridge type FCL number increases like this, the ability that double-fed wind power generator reply unbalance voltage is fallen can be supplied to.Such as only have A phase voltage to fall, the bridge-type fault limiter so only above A phase puts into operation, thus separately suppresses falling and not affecting B of A phase voltage, C phase voltage normal.

First brachium pontis of described rectifier circuit is identical with the structure of the 3rd brachium pontis, and the first brachium pontis comprises two diodes be connected in series.

Described second brachium pontis comprises the first switching tube, energy storage inductor, the first resistance, the second resistance and the first fly-wheel diode, the collector electrode of the emitter of the first switching tube connects one end of the first resistance and the positive pole of the first fly-wheel diode, the other end of the first resistance connects one end of energy storage inductor, the negative pole of the first fly-wheel diode connects one end of the second resistance, the other end of described energy storage inductor connects the other end of the second resistance, and the resistance of described second resistance is greater than the resistance of the first resistance.The energy stored in energy storage inductor consumes its energy stored by the first resistance and the second resistance simultaneously.Because the second resistance is a relatively very large resistance, so the energy in energy storage inductor discharges soon, what this design can make failure current limit circuit has the ability adapting to quick switch instances.

Described segmentation switching circuit comprises the 3rd resistance, the 4th resistance, the 5th resistance, second switch pipe and the 3rd switching tube, 3rd resistance, the 4th resistance are identical with the resistance of the 5th resistance, be connected to after described 3rd resistance, the 4th resistance and the 5th resistant series between the first brachium pontis mid point of rectification circuit and the 3rd brachium pontis mid point, second switch pipe is attempted by the two ends of the 4th resistance, and the 3rd switching tube is attempted by the two ends of the 5th resistance.

The low voltage ride through system of the described double-fed wind power generator based on failure current limit control comprises net side converter and rotor-side converter, low voltage ride through device comprises braking chopper circuit, one end of described net side converter connects equivalent electrical network, the other end of net side converter connects one end of rotor-side converter, the other end of rotor-side converter connects double-fed wind power generator rotor winding, braking chopper circuit is attempted by between the both positive and negative polarity of the DC bus between net side converter and rotor-side converter, described braking chopper circuit comprises the 4th switching tube, 6th resistance and the second fly-wheel diode, the collector electrode of described 4th switching tube connects the positive pole of DC bus, the emitter of the 4th switching tube connects the negative pole of DC bus by the 6th resistance, second fly-wheel diode is attempted by the two ends of the 6th resistance.Described braking chopper circuit can protect DC bus-bar voltage out of controlly to raise, braking chopper circuit and fault current limiter with the use of, when fault current limiter in systems in which switching time, likely also cause the shock effect to double-fed generator, by adopting braking chopper circuit, not only can limit DC bus-bar voltage to raise, the impact that the double-fed wind power generator fluctuation that simultaneously also can effectively suppress fault current limiter to drop into and to bring in excision process causes, the electric machine rotor electric current suppressing grid voltage sags to cause raises and DC bus-bar voltage raises.

The low voltage ride through system of the described double-fed wind power generator based on failure current limit control comprises control system and voltage sensor, and described voltage sensor is located at the exit of double-fed wind power generator, detects A phase B phase C phase voltage respectively.Control system judge each detect mutually set end voltage fall after fall scope, utilize corresponding to drop into and cutting method carries out low voltage crossing operation according to different Voltage Drop scopes.

Based on the low-voltage ride-through method of the low voltage ride through system of the double-fed wind power generator of failure current limit control, comprising:

When falling appears in voltage, the first switching tube, second switch pipe and the 3rd switching tube turn off according to different Voltage Drop scopes, and the 3rd resistance, the 4th resistance and the 5th resistance combined section drop into;

When voltage resume is normal, second switch pipe, the 3rd switching tube and the conducting successively of the first switching tube, excise successively by the 4th resistance, the 5th resistance and the 3rd resistance.

Described Voltage Drop scope is in 30%-50%, and when fault being detected: the first switching tube turns off, second switch pipe and the conducting simultaneously of the 3rd switching tube, the 3rd resistance drops into, and after failure removal: the first switching tube conducting, second switch pipe, the 3rd switching tube turns off.Electric current changes walks the second brachium pontis part, the 3rd resistance excision.

Voltage Drop scope is when 50%-70%, and when fault being detected: the first switching tube turns off, second switch pipe turns off, the 3rd switching tube conducting, and the 3rd resistance and the 4th resistance drop into.After failure removal: the first conducting of second switch pipe, the 4th resistance is cut, then the first switching tube conducting, and electric current changes walks the second brachium pontis part, the 3rd resistance excision;

Voltage Drop scope is when 70%-90%, and when fault being detected: the first switching tube turns off, and second switch pipe and the 3rd switching tube turn off simultaneously, the 3rd resistance, the 4th resistance and the 5th resistance drop into.After fault terminates: first second switch pipe conducting, the 4th resistance is cut.Then the 3rd switching tube conducting, the 5th resistance is cut.Last first switching tube conducting, electric current changes walks the second brachium pontis part, and the 3rd resistance is cut, recovers normally to run;

The described double-fed wind power generator system controlled based on failure current limit carries out switching process time difference between 3ms-6ms.When Voltage Drop occurs, the Current adjustment process of generator approximately can cause the time delay of a 1ms.The switching time of described segmentation switching process, between 3ms-6ms, can reach the actual object of segmental resection.If mute time interval is less than 1ms, motor do not make response will continue on once excise, now concerning motor, too fast excision small resistor is still equivalent to excise a large resistance; If mute time interval is greater than 6ms, then the mute time that system is total is just long, and when system voltage has recovered normally, machine end resistance excised again slowly, set end voltage can be caused for a long time higher than rated voltage, produce new fault.

The defining method of the equivalent resistance of described segmentation switching circuit is:

$\left|\stackrel{\→}{i}\right|=\frac{\left|\stackrel{\→}{S}\right|}{V\×10\%\×\sqrt{3}};$

$R_k\×\left|\stackrel{\→}{i}\right|=90\%\×V;$

$R_3=R_4=R_5=\frac{R_k}{3}$

In formula: be the capacity of generator outlet transformer, V is generator outlet voltage, R _kit is the equivalent resistance of segmentation switching circuit.

The utility model compared with prior art has following effect: fault current limiter is as the effective technical measures of one, the capacity of short circuit of electrical network can be limited, thus greatly alleviate dynamic, the thermally-stabilised burden of the various high voltage electric equipments such as circuit breaker, improve its Reliability of Microprocessor and useful life, ensure that the safety and stablization of electrical network are run.On the other hand, owing to limiting capacity of short circuit, likely significantly reduce electric equipment various in electrical network, as transformer, circuit breaker, instrument transformer etc., and the design capacity requirement of electric network composition, greatly reduce investment outlay.Fault current limiter fault current limiting of the present utility model and effectively draw high motor stator side voltage, has better low voltage crossing performance.

Accompanying drawing explanation

Fig. 1, overall structure schematic diagram of the present utility model;

Fig. 2, the circuit theory diagrams of the utility model fault current limiter;

Fig. 3, the schematic diagram of braking chopper circuit of the present utility model;

Fig. 4, control strategy block diagram of the present utility model;

Fig. 5; under different situations during Voltage Drop; the waveform of double-fed wind power generator rotor electric current; wherein Fig. 5 (a) is wind power generator rotor three-phase current waveform during unprotect during Voltage Drop; when Fig. 5 (b) is for adding traditional crowbar circuit; the three-phase current waveform of wind power generator rotor; Fig. 5 (c) is for adding the three-phase current waveform of the wind power generator rotor after fault current limiter of the present utility model; the abscissa of Fig. 5 (a), Fig. 5 (b) and Fig. 5 (c) is the time, and ordinate represents the multiple of rated current.

Fig. 6; under different situations during Voltage Drop; the waveform of double-fed aerogenerator stator electric current; wherein Fig. 6 (d) is motor stator three-phase current waveform during unprotect device during Voltage Drop; when Fig. 6 (e) is for adding traditional crowbar circuit; aerogenerator stator three-phase current waveform; Fig. 6 (f) is for adding the stator three-phase current waveform of the wind-driven generator after fault current limiter of the present utility model; the abscissa of Fig. 6 (d), Fig. 6 (e) and Fig. 6 (f) is the time, and ordinate represents the multiple of rated current.

Embodiment

Accompanying drawings the utility model embodiment, the low voltage ride through system of the double-fed wind power generator based on failure current limit control of the present utility model, comprise double-fed wind power generator DFIG and low voltage ride through device, low voltage ride through device comprises fault current limiter BFCL, as depicted in figs. 1 and 2, described fault current limiter BFCL is located between equivalent electrical network B and double-fed wind power generator DFIG stator, described fault current limiter BFCL comprises rectifier circuit and segmentation switching circuit, described rectifier circuit comprises the first brachium pontis, second brachium pontis and the 3rd brachium pontis, equivalence electrical network B connects the mid point of the first brachium pontis, the mid point of the 3rd brachium pontis connects double-fed wind power generator DFIG, described segmentation switching circuit is connected between the mid point of the first brachium pontis and the mid point of the 3rd brachium pontis.

The number of described fault current limiter BFCL is three, is located at three connections of equivalent electrical network B and double-fed wind power generator respectively.

First brachium pontis of described rectifier circuit is identical with the structure of the 3rd brachium pontis, and the first brachium pontis comprises two diode D1 and D3 be connected in series, and the second brachium pontis comprises two diode D2 and D4 be connected in series.

Described second brachium pontis comprises the first switching tube IGBT1, energy storage inductor L, the first resistance R1, the second resistance R2 and the first sustained diode 5, the collector electrode of the emitter of the first switching tube IGBT1 connects one end of the first resistance R1 and the positive pole of the first sustained diode 5, the other end of the first resistance R1 connects one end of energy storage inductor L, the negative pole of the first sustained diode 5 connects one end of the second resistance R2, and the other end of described energy storage inductor L connects the other end of the second resistance R2.

Described segmentation switching circuit comprises the 3rd resistance R3, the 4th resistance R4, the 5th resistance R5, second switch pipe IGBT2 and the 3rd switching tube IGBT3,3rd resistance R3, the 4th resistance R4 are identical with the resistance of the 5th resistance R5, be connected between the first brachium pontis mid point of rectification circuit and the 3rd brachium pontis mid point after described 3rd resistance R3, the 4th resistance R4 and the 5th resistance R5 series connection, the two ends being attempted by the 4th resistance R4 of second switch pipe IGBT2, the collector and emitter of the 3rd switching tube IGBT3 is attempted by the two ends of the 5th resistance R5.

The low voltage ride through system of the described double-fed wind power generator based on failure current limit control comprises net side converter GSC and rotor-side converter RSC, low voltage ride through device comprises braking chopper circuit A, one end of described net side converter GSC connects equivalent electrical network B, the other end of net side converter GSC connects one end of rotor-side converter RSC, the other end of rotor-side converter RSC connects the rotor windings of double-fed wind power generator DFIG, braking chopper circuit A is attempted by between the both positive and negative polarity of the DC bus between net side converter GSC and rotor-side converter RSC, described braking chopper circuit A comprises the 4th switching tube IGBT4, 6th resistance R6 and the second sustained diode 6, the collector electrode of described 4th switching tube IGBT4 connects the positive pole of DC bus, the emitter of the 4th switching tube IGBT4 connects the negative pole of DC bus by the 6th resistance R6, second sustained diode 6 is attempted by the two ends of the 6th resistance R6.

As shown in Figure 3, braking chopper circuit A is the electric equipment being connected to back-to-back DC bus, and object is that protection DC bus-bar voltage can not out of controlly raise.Whether brake chopper is made up of a resistance, control to connect by the 4th switching tube IGBT4.In order to avoid opening the overvoltage produced in turn off process, in other in parallel second sustained diode 6 of resistance.When DC bus-bar voltage exceedes control system set point, the 4th switching tube IGBT4 is open-minded, drops into resistance consumption fall unnecessary energy in DC bus side.6th resistance R6 keeps connecting always, until voltage is reduced to minimum set point, at this time turns off the 4th switching tube IGBT4, excises resistance from DC bus.

The low voltage ride through system of the described double-fed wind power generator based on failure current limit control comprises control system and voltage sensor, described voltage sensor is located at the exit of double-fed wind power generator, detect A phase B phase C phase voltage respectively, the output of control system controls turning on and off of the first switching tube IGBT1, second switch pipe IGBT2, the 3rd switching tube IGBT3 and the 4th switching tube IGBT4 respectively.

Based on the low-voltage ride-through method of the low voltage ride through system of the double-fed wind power generator of failure current limit control, comprise control system judge each detect mutually set end voltage fall after fall scope, utilize corresponding input and cutting method to carry out low voltage crossing operation according to different Voltage Drop scopes, be specially:

Under electrical network normal condition, the signal of the first switching tube IGBT1 is high level, and the first switching tube IGBT1 is in opening state.Power network current flows through rectifier circuit part at positive half period by D1-L-R1-IGBT1-D4.Under power network current negative half-cycle, electric current flows through rectifier bridge part by D2-L-R1-IGBT1-D3.All the time be from top to bottom by the electric current of energy storage inductor L and the first resistance R1 like this, energy storage inductor part can be similar to and be considered as short circuit.Due to energy storage inductor L reactance value and the first resistance R1 resistance value all very little, the equivalent resistance R of segmentation switching circuit _kbe again a very large resistance, the electric current overwhelming majority flows through from rectifier bridge part.Whole circuit to external world affect master will for R _kthe a small amount of leakage current passed through, the on-state voltage drop of the first sustained diode 5, the pressure drop that the first resistance R1 of the inductance L of low reactance value, little resistance causes, the on-state voltage drop of the first switching tube IGBT1, this few part is compared very small can neglecting with electrical network and is fallen to disregarding.

When line voltage falls suddenly, now often along with impulse current.Energy storage inductor L can be used for suppressing the unexpected impulse current produced.Control system makes the first switching tube IGBT1 signal become low level subsequently, and the first switching tube IGBT1 turns off, and the signal of second switch pipe IGBT2 is low level, and second switch pipe IGBT2 turns off.The signal of the 3rd switching tube IGBT3 is low level, and the 3rd switching tube IGBT3 turns off.Power network current changes the part of by-passing the 3rd resistance R3, the 4th resistance R4 and the 5th resistance R5 series connection, is equivalent to be connected in series a large resistance R in stator side _k, by stator side voltage high, falling of stator side voltage can be suppressed; On the other hand, the energy stored in energy storage inductor L is passed by by L-R1-D5-R2 path, and R1, R2 consume the energy in L simultaneously.

Voltage Drop scope in 30%-50%, second switch pipe IGBT2 and the 3rd switching tube IGBT3 conducting simultaneously, the 3rd resistance R3 drops into;

Voltage Drop scope is when 50%-70%, and second switch pipe IGBT2 turns off, the 3rd switching tube IGBT3 conducting, and the 3rd resistance R3 and the 5th resistance R5 drops into;

Voltage Drop scope is when 70%-90%, and second switch pipe IGBT2 and the 3rd switching tube IGBT3 turns off simultaneously, and the 3rd resistance R3, the 4th resistance R4 and the 5th resistance R5 drop into.

Recover normally, due to the equivalent resistance R of segmentation switching circuit at line voltage _kitself be also a large resistance, certain set end voltage can be caused equally to fall if it excised completely suddenly.At this moment the utility model takes segmental resection mode to degree of depth Voltage Drop, for 90% Voltage Drop situation; At excision the 3rd resistance, the 4th resistance, takes following rule during the 5th resistance.First make the signal of second switch pipe IGBT2 be high level, the leading conducting of second switch pipe IGBT2, be equivalent to connect the 3rd resistance R3, the 4th resistance R4 and the 5th resistance R5 in the 4th resistance R4 short circuit, equivalent resistance R _kresistance diminishes.Then the signal of the 3rd switching tube IGBT3 is become high level, make the 3rd switching tube IGBT3 conducting, by the 5th resistance R5 short circuit, reduce equivalent resistance R further _kresistance.The signal of the first switching tube IGBT1 is finally made to become high level.Electric current changes walks rectifier circuit part.Equivalent resistance R _kexcise from system completely, recover normally to run.

The low voltage ride through system of the described double-fed wind power generator based on failure current limit control carries out switching process time difference between 3ms-6ms.

The defining method of the equivalent resistance of described each resistance of segmentation switching circuit is:

$\left|\stackrel{\→}{i}\right|=\frac{\left|\stackrel{\→}{S}\right|}{\sqrt{3}\×V\×10\%};$

$R_k\×\left|\stackrel{\→}{i}\right|=90\%\×V;$

$R_3=R_4=R_5=\frac{R_k}{3}$

In formula: for the short circuit current vector on bus, be the capacity of generator DFIG outlet transformer, V is generator DFIG exit potential, R _kit is the equivalent resistance of segmentation switching circuit.

The simulink assembly in matlab is adopted to carry out emulation experiment, adopt the double-fed wind power generator model that simulink carries, under the short circuit of power network line three-phase ground causes set end voltage Voltage Drop 90% situation, double-fed wind power generator group is adding the contrast of low voltage ride-through capability before and after this patent, and concrete emulation experiment process comprises:

Add a short trouble module Three-PhaseFault in net side near motor part in parallel, by parameter phase A wherein, B, C all choose, and choose GroundFault item, resistance to earth are set to 0.00001 Ω.Fault time is set to 0.2 ~ 0.3s.Through this step, get final product the situation that analog machine terminal voltage 90% is fallen.

1, simulink model buildings Fig. 2 circuit is utilized, wherein: L=0.001H, R1=0.001 Ω, R2=800 Ω, R3=20 Ω, R4=20 Ω, R5=20 Ω, the control signal of each switching tube adopts pulse signal to replace, pulse signal low level during the control signal 0.2 ~ 0.31s of IGBT1, all the other moment are high level, pulse signal high level during the control signal 0.303s ~ 0.31s of IGBT2, all the other moment are low level, pulse signal high level during the control signal 0.307s ~ 0.31s of IGBT3, all the other moment are low level.

2, utilize simulink model, structure shown in accompanying drawing 3 is built out.Wherein the control signal of R4=1.5 Ω, switching tube adopts pulse signal to replace, and pulse signal high level during 0.2 ~ 0.31s, all the other moment are low level.

3, emulation experiment is carried out, checking low voltage crossing effect.

As shown in Figure 4: normal before not adding this patent, maximum 5 times of reaching normal amplitude of double-fed wind power generator rotor current amplitude in Voltage Drop 90% situation, and multiple peak value is all at more than 2 times of normal current amplitude.After adding this patent, in Voltage Drop 90% situation, double-fed wind power generator rotor current amplitude only has a peak value to reach 2.6 times of normal condition, and all the other moment waveforms amplitude are substantially steady.Compared with current widely used crowbar circuit, tool has the following advantages:

Although traditional crowbar circuit provides low voltage ride-through capability, but be equivalent to squirrel-cage induction generator during fault run, it needs to absorb idle from electrical network, but the idle deficiency of line voltage reduction itself, and motor now absorbs the idle recovery being unfavorable for voltage from electrical network.

In the wind power plant of reality, have multiple stage double-fed wind power generator, braking chopper circuit is that crowbar and this patent all need to use, so all want every platform motor to install one.But crowbar circuit method needs each motor to fill establishes a crowbar circuit again.BFCL only needs a connected at multiple electric motors, and on b, c three-phase bus, installing just can provide all voltage ride through capability of wind driven generators.

As shown in Figure 5: normal before not adding this patent, maximum 5 times of reaching normal amplitude of double-fed aerogenerator stator current amplitude in Voltage Drop 90% situation, and multiple peak value is all at more than 2 times of normal current amplitude.After adding this patent, in Voltage Drop 90% situation, double-fed aerogenerator stator current amplitude only has a peak value to reach 2.3 times of normal condition, and all the other moment waveforms amplitude are substantially steady.With add compared with current waveform that traditional crowbar circuit produces, it is better that stator current maximum amplitude suppresses, so better to double fed electric machine rotor side protected effect.

By emulation experiment, demonstrate the ability that this device well can strengthen double-fed wind power generator low voltage crossing really.

The exemplary illustration of present embodiment just to this patent, does not limit its protection range, and those skilled in the art can also change, as long as no the Spirit Essence exceeding this patent, in the protection range of this patent its local.

Claims (6)

1. based on the low voltage ride through system of the double-fed wind power generator of failure current limit control, comprise double-fed wind power generator and low voltage ride through device, it is characterized in that: described low voltage ride through device comprises fault current limiter, fault current limiter is located between double-fed wind power generator and equivalent electrical network, described fault current limiter comprises rectifier circuit and segmental resection circuit, described rectifier circuit comprises the first brachium pontis, second brachium pontis and the 3rd brachium pontis, equivalence electrical network connects the mid point of the first brachium pontis, the mid point of the 3rd brachium pontis connects double-fed wind power generator, described segmental resection circuit is also connected between the mid point of the first brachium pontis and the mid point of the 3rd brachium pontis.

2., according to claim 1 based on the low voltage ride through system of the double-fed wind power generator of failure current limit control, it is characterized in that: the number of described fault current limiter is three, is located at three connections of equivalent electrical network and double-fed wind power generator respectively.

3., according to claim 1 based on the low voltage ride through system of the double-fed wind power generator of failure current limit control, it is characterized in that: the first brachium pontis of described rectifier circuit is identical with the structure of the 3rd brachium pontis, the first brachium pontis comprises two diodes be connected in series.

4. according to claim 1 based on the low voltage ride through system of the double-fed wind power generator of failure current limit control, it is characterized in that: described second brachium pontis comprises the first switching tube, energy storage inductor, the first resistance, the second resistance and the first fly-wheel diode, the collector electrode of the emitter of the first switching tube connects one end of the first resistance and the positive pole of the first fly-wheel diode, the other end of the first resistance connects one end of energy storage inductor, the negative pole of the first fly-wheel diode connects one end of the second resistance, and the other end of described energy storage inductor connects the other end of the second resistance.

5. according to claim 1 based on the low voltage ride through system of the double-fed wind power generator of failure current limit control, it is characterized in that: described segmental resection circuit comprises the 3rd resistance, the 4th resistance, the 5th resistance, second switch pipe and the 3rd switching tube, 3rd resistance, the 4th resistance are identical with the resistance of the 5th resistance, be connected to after described 3rd resistance, the 4th resistance and the 5th resistant series between the first brachium pontis mid point of rectification circuit and the 3rd brachium pontis mid point, second switch pipe is attempted by the two ends of the 4th resistance, and the 3rd switching tube is attempted by the two ends of the 5th resistance.

6. according to claim 1 based on the low voltage ride through system of the double-fed wind power generator of failure current limit control, it is characterized in that: the low voltage ride through system of the described double-fed wind power generator based on failure current limit control comprises net side converter and rotor-side converter, low voltage ride through device comprises braking chopper circuit, one end of described net side converter connects equivalent electrical network, the other end of net side converter connects one end of rotor-side converter, the other end of rotor-side converter connects double-fed wind power generator rotor winding, braking chopper circuit is attempted by between the both positive and negative polarity of the DC bus between net side converter and rotor-side converter, described braking chopper circuit comprises the 4th switching tube, 6th resistance and the second fly-wheel diode, the collector electrode of described 4th switching tube connects the positive pole of DC bus, the emitter of the 4th switching tube connects the negative pole of DC bus by the 6th resistance, second fly-wheel diode is attempted by the two ends of the 6th resistance.