CN203787969U - Doubly-fed wind turbine grid-connected power generation system - Google Patents
Doubly-fed wind turbine grid-connected power generation system Download PDFInfo
- Publication number
- CN203787969U CN203787969U CN201420135627.3U CN201420135627U CN203787969U CN 203787969 U CN203787969 U CN 203787969U CN 201420135627 U CN201420135627 U CN 201420135627U CN 203787969 U CN203787969 U CN 203787969U
- Authority
- CN
- China
- Prior art keywords
- grid
- double
- switching device
- fed
- power generation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/76—Power conversion electric or electronic aspects
Landscapes
- Control Of Eletrric Generators (AREA)
Abstract
The utility model discloses a doubly-fed wind power generation grid-connected system. The system comprises a doubly-fed generator, a grid-connected circuit breaker connected between a stator of the doubly-fed generator and a power grid, and a converter and a main contactor which are sequentially connected between a rotor of the doubly-fed generator and the grid-connected circuit breaker. The system further comprises a grid-connected switching device connected between the stator of the doubly-fed generator and the grid-connected circuit breaker. The grid-connected switching device comprises three switching units of which each is connected to the line of one phase, and each switching unit comprises at least two switching tubes reversely connected in parallel. The grid-connected system further comprises a control unit, which is used for outputting a driving signal to enable the three switching units to be switched on to realize grid connection when the difference of voltages of any two phase lines corresponding to the two ends of the grid-connected switching device is smaller than a preset value. The doubly-fed wind power generation grid-connected system of the utility model has the advantages of small impulse current in grid connection, and high resistance to short-circuit current impact.
Description
Technical field
The utility model relates to technical field of wind power generation, more particularly, relates to a kind of double-fed blower fan grid-connected system.
Background technology
In recent years, fast development along with China's wind power generation cause, China wind-powered electricity generation installation total amount and a year newly-increased installed capacity all leap into the front ranks of the world, and main blower fan type is in the market double-fed and two kinds of direct-driving types, wherein the leading share of double-fed blower fan occuping market.Surge along with double-fed blower fan installed capacity, also many problems have been exposed gradually, wherein grid-connected contactor is as one of critical component of blower fan, the reliability of its use and how to reduce impulse current when grid-connected and all become one of focal issue of main research in recent years.
As shown in Figure 1, double-fed generator 3 rotors connect current transformer 6 to the double-fed blower fan system topological structure of the main flow of existing occuping market, and current transformer 6 connects electrical network by main contactor 7, grid-connected circuit breaker 5; Doubly-fed generation machine stator is through grid-connected contactor 4 ', and grid-connected circuit breaker 5 is connected to electrical network.During fan parking, generator need disconnect with electrical network, during operation, need be communicated with electrical network, and this just requires grid-connected switching device frequent movement.The useful life of circuit breaker is shorter, is generally 10000 left and right of switch, and the switching device that is therefore not suitable as frequent movement is used.And the useful life of contactor is longer; general on-off times is over 100000 times; so increase a grid-connected contactor between doubly-fed generation machine stator and grid-connected circuit breaker; while being responsible for the normal start and stop of blower fan; play between generator and electrical network and connect and buffer action; grid-connected circuit breaker is always in closure state in normal condition, and the protection of just threading off while the catastrophe failure such as being only short-circuited, to increase the life-span of grid-connected circuit breaker.
This double feed wind power generator and network process mainly realize in two steps: the first step, start current transformer to double-fed generator carry out excitation adjusting double-fed generator stator side voltage-phase, frequency, amplitude and electric network voltage phase, frequency, amplitude is consistent; Second step, closed grid-connected contactor is communicated with electrical network, realizes and network process.In first step process, double-fed generator stator side voltage-phase, frequency, amplitude and electric network voltage phase, frequency, amplitude can be adjusted to more approaching, but still have some errors, when therefore grid-connected contactor is closed in second step process, can cause very large impulse current.Therefore in existing dual feedback wind power generation system, adopt grid-connected contactor to realize grid-connected meeting and have following defect:
1) grid-connected impulse current is larger, and when grid-connected, the voltage difference at grid-connected contactor two ends can cause larger impulse current;
2) breaking capacity of contactor is very little and resistance to rush of current ability is little, when double-fed generator stator side is short-circuited fault, because circuit breaker breaking speed is slower, about about a few tens of milliseconds, the short circuit current that during this period of time grid-connected contactor need to bear is the more than more than ten times of system nominal current greatly.
In prior art, for fear of above-mentioned situation, need select the grid-connected contactor of larger grade, this has increased cost undoubtedly.
Utility model content
The technical problems to be solved in the utility model is, the defect of, poor reliability large for the above-mentioned grid-connected impulse current of prior art, provides a kind of double-fed wind-driven power generation system and control method thereof.
The utility model solves the technical scheme that its technical problem adopts: construct a kind of double-fed wind-driven power generation grid-connected system, comprise double-fed generator, be connected to stator and the grid-connected circuit breaker between electrical network of described double-fed generator and be connected to the rotor of described double-fed generator and current transformer and the main contactor between described grid-connected circuit breaker in turn, also comprise and be connected to the stator of described double-fed generator and the grid-connected switching device between described grid-connected circuit breaker, wherein: described grid-connected switching device comprises three switch elements that access respectively each phase circuit, each switch element includes at least two switching tubes that inverse parallel connects,
Described grid-connected system also comprises control unit, when described control unit is less than a preset value for the absolute value of difference between the corresponding any two phase line voltages in grid-connected switching device two ends, output drive signal makes three switch elements all grid-connected to realize in conducting state.
In above-mentioned double-fed wind-driven power generation grid-connected system, described switching tube is thyristor.
In above-mentioned double-fed wind-driven power generation grid-connected system, described switching tube is gate level turn-off thyristor.
In above-mentioned double-fed wind-driven power generation grid-connected system, described control unit comprises a signal detection module, and described signal detection module is for detection of the corresponding any two phase line magnitudes of voltage in described grid-connected switching device two ends.
In above-mentioned double-fed wind-driven power generation grid-connected system, described control unit also comprises a signal comparison module, and described signal comparison module is used for described line magnitude of voltage to compare, and exports the first comparative result when the absolute value of its difference is less than described preset value.
In above-mentioned double-fed wind-driven power generation grid-connected system, described control unit also comprises a driving signaling module, and described driving signaling module is given described grid-connected switching device for output drive signal when described signal comparison module is exported the first comparative result.
Implement double-fed wind-driven power generation system of the present utility model, there is following beneficial effect: by adopting grid-connected switching device, this grid-connected switching device comprises three switch elements that access respectively each phase circuit, each switch element comprises at least two switching tubes that inverse parallel connects, and switching tube adopts thyristor or gate level turn-off thyristor, therefore completely can be before grid-connected when any one group of corresponding line voltage curve in grid-connected switching device two ends approaches its crosspoint, in this moment point, controlling three switch elements all makes double-fed generator be communicated with electrical network in conducting state, realize the seamless connection of electrical network and stator voltage, grid-connected impulse current is very little.In addition,, when fan parking or double-fed generator stator side are short-circuited fault, also on-off switching tube in a short period of time, makes grid-connected switching device in off-state, isolation short circuit current.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, the utility model is described in further detail, in accompanying drawing:
Fig. 1 is the topological structure schematic diagram of existing double-fed wind-driven power generation system;
Fig. 2 is the topological structure schematic diagram of the utility model double-fed wind-driven power generation system embodiment;
Fig. 3 is the schematic diagram of grid-connected switching device in Fig. 2;
Fig. 4 is the Function Extension schematic diagram of grid-connected switching device in Fig. 2;
Fig. 5 is the grid-connected front grid side AB phase line voltage of 1.5MW double-fed wind-driven power generation system and stator side AB phase line voltage synchronous oscillogram;
Fig. 6 is 1.5MW dual feedback wind power generation system grid side AB phase line voltage, stator side AB phase line voltage, grid side A phase current waveform figure when grid-connected;
Fig. 7 is grid-connected switching device both end voltage cross point detection schematic diagram in Fig. 2;
Fig. 8 is link curve chart in dead band in Fig. 7.
Embodiment
For technical characterictic of the present utility model, object and effect being had more clearly, understand, now contrast accompanying drawing and describe embodiment of the present utility model in detail.
As shown in Figure 2, for the topological structure schematic diagram of the utility model double-fed wind-driven power generation system embodiment, this double-fed wind-driven power generation system comprises fan blade 1, gear box 2, double-fed generator 3, grid-connected switching device 4, grid-connected circuit breaker 5, current transformer 6 and main contactor 7.Wherein: fan blade 1, gear box 2 connect successively, grid-connected switching device 4 and grid-connected circuit breaker 5 are connected in turn between the stator and electrical network of double-fed generator 3, and current transformer 6 and main contactor 7 are connected in turn between double-fed generator 3 rotors and grid-connected switching device 4 and the tie point of grid-connected circuit breaker 5.Current transformer 6 comprise pusher side current transformer, net side converter and be connected to pusher side current transformer and net side converter between storage capacitor, wherein: the interchange end of pusher side current transformer is connected with the rotor of double-fed generator 3, the interchange end of net side converter is connected with main contactor 7, and pusher side current transformer is connected with storage capacitor two ends with the public direct-current end of net side converter.
Especially, grid-connected switching device 4 comprises three switch elements that access respectively each phase circuit, each switch element includes at least two switching tubes that inverse parallel connects, as shown in Figure 3, this grid-connected switching device 4 consists of six or above switching tube, in the present embodiment, be preferably thyristor or gate level turn-off thyristor.It is grid-connected to realize in conducting state when this grid-connected switching device 4 is less than a preset value for the absolute value of the difference between the corresponding any two phase line voltages in its two ends.
Referring to Fig. 2 and Fig. 4, this system also comprises a control unit 61 in the present embodiment, and this control unit 61 comprises signal detection module 611, signal comparison module 612 and drives signaling module 613.Signal detection module 611 is for detection of the corresponding any two phase line voltages in grid-connected switching device 4 two ends, signal comparison module 612 compares for the corresponding any two phase line voltages in grid-connected switching device two ends that signal detection module 611 is recorded, when the absolute value of its difference is less than a preset value, output the first comparative result; When the absolute value of its difference is more than or equal to this preset value, output the second comparative result.Drive signaling module 613 for output drive signal when signal comparison module 612 output the first comparative result all switching tubes to grid-connected switching device, control three switch elements in grid-connected switching device all in conducting state, realize grid-connected.The difference between any two phase line voltages at grid-connected switching device 4 two ends hour realize grid-connected, thereby can reduce greatly the grid-connected impulse current of wind generator system.The function of this control unit also can realize for controlling the current transformer control unit of the electronic switching device conducting of current transformer internal power and shutoff in current transformer 6.
In the present embodiment; grid-connected switching device 4 also comprises an absorbing circuit 41; the peak voltage of absorbing circuit 41 for reducing to produce when the switching tube turn-on and turn-off; can adopt conventional resistance-capacitance circuit to realize that (this resistance-capacitance circuit is common technology; be not repeated herein), protection switch pipe reliably working.
By adopt grid-connected switching device 4 in double-fed wind power generator, can reduce significantly grid-connected impulse current, get arbitrarily the corresponding line voltage in two ends in one group of grid-connected switching device, the 4 liang of end line voltages of grid-connected switching device of take are respectively the line voltage that A1 phase that in doubly-fed generation machine stator AB phase line voltage Vsab(Fig. 3, grid-connected switching device 4 is connected with the stator of double-fed generator is formed with B1 phase) the line voltage that formed of the A2 phase that is connected with electrical network with grid-connected switching device 4 in electrical network AB phase line voltage Vgab(Fig. 3 and B2 phase) be example, as shown in Figure 5, for the voltage waveform before grid-connected (more clear in order to illustrate, both phase differences have been strengthened, real process phase difference can be less), owing to needing first to start current transformer before grid-connected, double-fed generator is carried out to excitation, double-fed generator stator voltage phase place, frequency, amplitude and electric network voltage phase, frequency, amplitude can be adjusted to more approaching, but still have some errors, be that doubly-fed generation machine stator AB phase line voltage Vsab and electrical network AB phase line voltage Vgab can exist certain phase difference and difference in magnitude, so can there are two voltage crosspoints in its voltage curve of each cycle, at each its voltage difference of voltage crosspoint, be zero, in this moment point, carry out the grid-connected seamless connection that can realize electrical network and double-fed generator stator voltage.But grid-connected by adopting grid-connected contactor to realize in the prior art, more than its action delay often reaches 100ms, and each switch motion time delay often consistency is very poor, cause above method to be difficult to realize, in grid-connected contactor closure, realize when grid-connected and can have very large impulse current.
Therefore by adopting grid-connected switching tube device 4 to replace existing grid-connected contactor, this grid-connected switching device 4 comprises three switch elements that access respectively each phase circuit, each switch element consists of two or more switching tube inverse parallels, and switching tube is preferably thyristor or gate level turn-off thyristor, therefore switching tube is static switch device in the present embodiment, conducting speed is Microsecond grade, can be controlled at the grid-connected moment completely approaches voltage crosspoint, grid-connected impulse current is reduced greatly, as shown in Figure 6, the AB phase line voltage waveform at grid-connected switching device two ends when the subgraph of the first half is grid-connected, the subgraph of the latter half is the mutually grid-connected impulse current waveform of A, in conjunction with Fig. 5 and Fig. 6, when fan operation need be communicated with electrical network, and when the absolute value of the difference between the corresponding any two phase line voltages in grid-connected switching device two ends is less than a preset value, control unit output drive signal is controlled three switch elements in grid-connected switching device all in conducting state, because the switching tube in the present embodiment is thyristor or gate level turn-off thyristor, its conducting speed is Microsecond grade, can be controlled at place, voltage crosspoint completely realizes grid-connected, therefore grid-connected impulse current is very little.
Especially; if what the switching tube in grid-connected switching device adopted is thyristor; when fan parking; double-fed generator need disconnect with electrical network; control unit 61 will forbid that output drive signal is to grid-connected switching device, according to the characteristic of thyristor, in its current over-zero or the device automatic cut-off oppositely time of flowing through; now thyristor can automatically shut down, and its longest turn-off time is half of 10ms(line voltage cycle).When double-fed generator stator current is short-circuited fault; now can electric current to be detected excessive for control unit; and report over current fault; forbid that equally output drive signal is to grid-connected switching device; thyristor automatically shuts down; and the short circuit current turn-off time of each phase is the longest is 10ms; and the time that three-phase all turn-offs is 10ms～20ms; reduce more than one times than the circuit breaker tripping time; therefore shutoff short circuit current that can faster speed, thus current transformer and other core components in dual feedback wind power generation system better protected.
If what the switching tube in grid-connected switching device adopted is gate level turn-off thyristor, because gate level turn-off thyristor is full control device, when double-fed generator stator current is short-circuited fault, it is excessive and report over current fault that control unit can detect electric current, now can export a gate pole cut-off signals to grid-connected switching device, according to the characteristic of gate level turn-off thyristor, can in tens microseconds, automatically shut down, isolation short circuit current, therefore there is resistance to rush of current ability of good short time, thereby avoid burning when double-fed generator stator current is short-circuited fault.
As shown in Figure 7, for grid-connected switching device 4 both end voltage cross point detection schematic diagrams, the grid-connected switching device 4 electrical network AB phase line voltage Vgab that soon by signal comparison module 612, signal detection module 611 detected and doubly-fed generation machine stator AB phase line voltage Vsab compare, obtain its difference DELTA Vab=Vgab-Vsab, this signal comparison module 612 can be realized by hardware circuit, also can be realized by software program.When the absolute value of Δ Vab is more than or equal to the threshold values Vthd that preset value set, now signal comparison module 612 output the second comparative result S=1, represent that grid-connected switching device both end voltage is poor larger, can not be grid-connected; When the absolute value of Δ Vab is less than the threshold values Vthd of setting, now signal comparison module 612 is exported the first comparative result S=0, represent that grid-connected switching device both end voltage is poor very little, approach the voltage curve crosspoint of the grid-connected switching device both end voltage shown in Fig. 5, reach grid-connected condition, can be grid-connected, now control unit, according to this comparative result output drive signal to grid-connected switching device, is controlled in grid-connected switching device three switch elements all in conducting state.The threshold values Vthd that above-mentioned preset value is set can be made as 2% of system rated voltage amplitude, but is not limited to this.Take 1.5MW dual feedback wind power generation system as example, suppose that its rated voltage amplitude is 975.66V(690V*1.414), threshold values Vthd can be made as 19.5V(975.66V*2% so).
Fig. 8 is link curve chart in dead band in Fig. 7, and the value of Vthd can be with reference to above-mentioned described setting.-Vthd and+regional value of Vthd between, output S value is 0, represents that grid-connected switching device both end voltage is poor very little, reaches grid-connected condition, can carry out grid-connected.
In above-mentioned, be to take to compare to control and be example by detecting the corresponding AB phase line voltage in grid-connected switching device two ends, same, also can compare control by detecting the corresponding AC phase line voltage in grid-connected switching device two ends or BC phase line voltage.
Therefore, implement the utility model double-fed wind-driven power generation system, by adopting grid-connected switching device, this grid-connected switching device comprises three switch elements that access respectively each phase circuit, each switch element includes at least two switching tubes that inverse parallel connects, and switching tube adopts thyristor or gate level turn-off thyristor, therefore can be controlled at completely and approach voltage curve crosspoint before grid-connected and constantly make its grid-connected switching device realize double-fed generator in conducting state to be communicated with electrical network, now the difference between double-fed generator stator voltage and line voltage is less, therefore grid-connected impulse current is very little.In addition, when double-fed generator stator current is short-circuited fault, on-off switching tube, makes grid-connected switching device in off-state in a short period of time, isolation short circuit current.
By reference to the accompanying drawings embodiment of the present utility model is described above; but the utility model is not limited to above-mentioned embodiment; above-mentioned embodiment is only schematic; rather than restrictive; those of ordinary skill in the art is under enlightenment of the present utility model; not departing from the scope situation that the utility model aim and claim protect, also can make a lot of forms, within these all belong to protection of the present utility model.
Claims (6)
1. a double-fed wind-driven power generation grid-connected system, comprise double-fed generator, be connected to stator and the grid-connected circuit breaker between electrical network of described double-fed generator and be connected to the rotor of described double-fed generator and current transformer and the main contactor between described grid-connected circuit breaker in turn, it is characterized in that, also comprise and be connected to the stator of described double-fed generator and the grid-connected switching device between described grid-connected circuit breaker, wherein: described grid-connected switching device comprises three switch elements that access respectively each phase circuit, each switch element includes at least two switching tubes that inverse parallel connects;
Described grid-connected system also comprises control unit, when described control unit is less than a preset value for the absolute value of difference between the corresponding any two phase line voltages in grid-connected switching device two ends, output drive signal makes three switch elements all grid-connected to realize in conducting state.
2. according to double-fed wind-driven power generation grid-connected system claimed in claim 1, it is characterized in that, described switching tube is thyristor.
3. according to double-fed wind-driven power generation grid-connected system claimed in claim 1, it is characterized in that, described switching tube is gate level turn-off thyristor.
4. according to the arbitrary described double-fed wind-driven power generation grid-connected system of claim 2 or 3, it is characterized in that, described control unit comprises a signal detection module, and described signal detection module is for detection of the corresponding any two phase line magnitudes of voltage in described grid-connected switching device two ends.
5. according to double-fed wind-driven power generation grid-connected system claimed in claim 4, it is characterized in that, described control unit also comprises a signal comparison module, described signal comparison module is used for described line magnitude of voltage to compare, and exports the first comparative result when the absolute value of its difference is less than described preset value.
6. according to double-fed wind-driven power generation grid-connected system claimed in claim 5, it is characterized in that, described control unit also comprises a driving signaling module, and described driving signaling module is given described grid-connected switching device for output drive signal when described signal comparison module is exported the first comparative result.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420135627.3U CN203787969U (en) | 2014-03-24 | 2014-03-24 | Doubly-fed wind turbine grid-connected power generation system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420135627.3U CN203787969U (en) | 2014-03-24 | 2014-03-24 | Doubly-fed wind turbine grid-connected power generation system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203787969U true CN203787969U (en) | 2014-08-20 |
Family
ID=51324122
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420135627.3U Expired - Fee Related CN203787969U (en) | 2014-03-24 | 2014-03-24 | Doubly-fed wind turbine grid-connected power generation system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203787969U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103887819A (en) * | 2014-03-24 | 2014-06-25 | 深圳市长昊机电有限公司 | Doubly-fed fan grid-connected power generation system and control method |
-
2014
- 2014-03-24 CN CN201420135627.3U patent/CN203787969U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103887819A (en) * | 2014-03-24 | 2014-06-25 | 深圳市长昊机电有限公司 | Doubly-fed fan grid-connected power generation system and control method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102957163A (en) | Direct-current chopper and direct-current chopping method for doubly-fed induction generator system | |
| CN101340185B (en) | Synchronous control method of 3 phase AC solid power controller | |
| CN103217641A (en) | Device and method for testing CROWBAR circuit of wind power converter | |
| CN106877300A (en) | A kind of low-voltage direct breaker and test method | |
| CN102593809B (en) | Solid-state circuit breaker with over-voltage suppressing function | |
| CN102904280A (en) | Device and method for traversing grid fault by double-fed wind power converter | |
| CN101917156A (en) | Method and device for protecting wind generating set during electric network voltage dip in short time | |
| CN102315651B (en) | Crowbar circuit as well as device for double-fed induction generator to rid through power grid fault and method thereof | |
| CN102412597A (en) | Low voltage ride through control method and device for a double-fed wind power generation system | |
| CN204424866U (en) | A kind of current-limiting protection circuit and current-limiting protection device | |
| CN203787969U (en) | Doubly-fed wind turbine grid-connected power generation system | |
| CN101859157B (en) | Current compensation type alternating-current voltage stabilizer | |
| CN106300415B (en) | A kind of low-voltage ride-through method of brushless dual-feedback wind power generator group combination | |
| CN201985516U (en) | Isolation device for restraining high-tension transformer neutral point direct current by serial capacitance | |
| CN104022529A (en) | Doubly-fed wind generator low voltage ride through control method based on improved Crowbar | |
| CN203445627U (en) | Wind power generator set high and low voltage ride through device and system thereof | |
| CN103887819B (en) | Doubly-fed fan grid-connected power generation system and control method | |
| CN207010215U (en) | A kind of high voltage DC breaker | |
| CN102957157B (en) | Silicon controlled composite switch of intelligent zero-crossing switching | |
| CN109412466A (en) | The compound start stop apparatus of turbine emergency DC lubricating and control method | |
| CN204118716U (en) | A kind of distributed power source failure protecting device being applicable to multi-source electrical network | |
| CN204230905U (en) | Group wells Time-sharing control device | |
| CN203278602U (en) | A doubly-fed frequency converter with an improved chopper structure | |
| CN201766546U (en) | Wind generating set protector for coping with voltage dip of power grid | |
| CN203933037U (en) | A kind of double-fed wind generator current transformer Crowbar protective circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140820 |