CN209056943U - Low voltage ride through system and wind generator system - Google Patents
Low voltage ride through system and wind generator system Download PDFInfo
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- CN209056943U CN209056943U CN201821927221.3U CN201821927221U CN209056943U CN 209056943 U CN209056943 U CN 209056943U CN 201821927221 U CN201821927221 U CN 201821927221U CN 209056943 U CN209056943 U CN 209056943U
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Abstract
This application involves low voltage crossing technical field more particularly to a kind of low voltage ride through system and wind generator system.Low voltage ride through system includes: relay, and the current transformer, first voltage mutual inductor and the switching device that are separately connected with the relay, further includes the resistance-capacitance circuit in parallel with the switching device, which includes at least one capacitor element；Wherein, which is used to detect rotor current and the current value that will test is sent to relay；The first voltage mutual inductor is used to detect the voltage of grid entry point and the voltage value that will test is sent to relay；The relay is less than predetermined voltage threshold in the voltage value received, and when receiving the current value less than predetermined current threshold, sends electric signal to switching device and triggers the switching device from closed state to disconnect so that the resistance-capacitance circuit accesses rotor windings.The application accesses rotor windings by resistance-capacitance circuit, helps that rotor current is inhibited to rise；Capacitor can also be sent reactive power to power grid and be restored with auxiliary power grid.
Description
Technical field
This application involves low voltage crossing technical fields, more particularly, to low voltage ride through system and wind generator system.
Background technique
The low voltage crossing mode of double-fed blower can be classified as two major classes at present: one kind is to improve Traditional control strategy；It is another
Class is to add hardware device.The first kind, which mainly passes through, is added feedforward compensation or electrical using the certain transient state of " demagnetization " means quickening
The rate of decay of amount realizes low voltage crossing with its amplitude is reduced, but such mode can be limited to the capacity of current transformer, generally
The situation lighter for Voltage Drop；And when facing catastrophe failure, investment hardware device is more directly effective, wherein crow bar
Crowbar protection is the most classical, has many advantages, such as that structure is simple, current limitation effect is good, but after its investment, rotor windings and rotor-side
The connection of current transformer (RSC) is disconnected, and DFIG operation is similar to asynchronous machine, is in runaway condition, therefore unit will be from power grid
Middle absorption is idle with excitation, deteriorates grid entry point Voltage Drop degree.Research about crow bar crossing technology focuses on crow bar mostly
The optimization of resistance value and switching time has scholar to propose dynamic adjustment crow bar resistance to improve the ability for taking into account various failure situations
The mode of value can inhibit rotor current under different degrees of Voltage Drop, and can prevent DC bus-bar voltage is more than threshold value,
Effectively increase the flexibility of protection；Later in order to get rid of crowbar protection propose rotor-side series resistor scheme, this scheme
Advantage is there is more direct inhibitory effect to electric current, the disadvantage is that optimal resistance is difficult in the case where not cooperating with other schemes
With determination, if the too big possible stability for influencing rotor lateral circuit of the resistance value sealed in when minor failure, and when catastrophe failure such as
It is bad that fruit seals in the too small then current limitation effect of resistance value.
Summary of the invention
In view of this, the embodiment of the present application provides a kind of low voltage ride through system and wind generator system, turn to limit
Electron current increases, and auxiliary power grid restores, and improves low voltage crossing performance.
In a first aspect, the embodiment of the present application provides a kind of low voltage ride through system, comprising: relay, and with this after
Current transformer, first voltage mutual inductor and the switching device that electric appliance is separately connected, further include the resistance in parallel with the switching device
Capacitive circuit, the resistance-capacitance circuit include at least one capacitor element；Wherein,
The current transformer is used to detect the rotor current in objective circuit and the current value that will test is sent to relay；
The first voltage mutual inductor is used to detect the voltage of the grid entry point in the objective circuit, and the voltage value hair that will test
Give relay；
The relay is used to be less than predetermined voltage threshold in the voltage value received, and receives the current value and be less than in advance
When constant current threshold value, it is switched to off-state from closed state to the switching device is triggered with switching device transmission electric signal,
So that the resistance-capacitance circuit accesses rotor windings.
In preferred embodiments of the present invention, which further includes the crowbar circuit connecting with the relay and second voltage
Mutual inductor；The second voltage mutual inductor is also used to detect the DC bus-bar voltage in the objective circuit, and the direct current that will test is female
Line voltage value is sent to relay；
The relay is also used to be greater than the predetermined current threshold in the current value received；Or the DC bus-bar voltage
Value be greater than predetermined direct current busbar voltage threshold value when, to the insulated gate bipolar transistor IGBT of the crowbar circuit send electric signal with
Make the rotor windings circuit communication of the crowbar circuit Yu the objective circuit.
In preferred embodiments of the present invention, which further includes the reactive power compensation device connecting with the relay；
When the relay is also used to send electric signal to the insulated gate bipolar transistor IGBT of the crowbar circuit, to the nothing
Reactive power compensation device sends starting electric signal；
Electricity of the reactive power compensation device for starting and being connected to the objective circuit when receiving the starting electric signal
Net conveys reactive power to stablize the voltage of the grid entry point.
In preferred embodiments of the present invention, the reactive power compensation device is grid-side converter.
In preferred embodiments of the present invention, which includes pi regulator, the first input of the pi regulator
End input stator voltage reference value；Second input terminal is connected with the first voltage mutual inductor, receives the voltage value of simultaneously network interface；The PI
The output end of adjuster exports q shaft current reference value；The q shaft current reference value is for generating reactive power.
In preferred embodiments of the present invention, if the relay is also used to the rotor current that the current transformer detects
Value is less than predetermined current threshold, sends electric signal to the IGBT of crowbar circuit so that the crowbar circuit and rotor windings excision point
From.
In preferred embodiments of the present invention, which includes resistance, and the resistance and the capacitor element are connected in series.
In preferred embodiments of the present invention, which includes resistance, which is connected in parallel with the capacitor element.
It is electric including first comparator, the second comparator and with door inside the relay in preferred embodiments of the present invention
Road；The output end of the first comparator connects the first input end of the AND gate circuit；The output end connection of second comparator should
Second input terminal of AND gate circuit；
The first input end of the first comparator is used to receive the voltage value of first voltage mutual inductor transmission；Second input
End is for receiving the predetermined voltage threshold；Compare the size of the voltage value and predetermined voltage threshold received；If received
The voltage value arrived is less than the predetermined voltage threshold, and output end exports low level；
The first input end of second comparator is used to receive the current value of current transformer transmission；Second input terminal is used
In reception current threshold；Compare the size of the current value received and predetermined current threshold；If it is small to receive the current value
When predetermined current threshold, output end exports low level；
The output end of the AND gate circuit connects the control terminal of the switching device as the output end of the relay.
Second aspect, the embodiment of the present application also provides a kind of system, including wind-driven generator and low voltage ride through system,
The circuit of the wind-driven generator is connect with above-mentioned low voltage ride through system.
Using the above scheme, relay triggers the switching device from closed state switching to switching device transmission electric signal
For off-state, so that the resistance-capacitance circuit accesses rotor windings；Rotor current is limited by concatenation capacitance-resistance, capacitor can not only be inhaled
Receiving excess energy can also issue a little idle, play the effect of auxiliary power grid recovery.
Further, the application has also carried out following improvement and has achieved good effect, when catastrophe failure, relay to
The insulated gate bipolar transistor IGBT of crowbar circuit send electric signal so that the rotor of the crowbar circuit and the objective circuit around
Group circuit communication；By investment resistance-capacitance circuit and crowbar circuit, so that the resistance of rotor equivalent circuit increases, inhibition electricity is improved
The effect of stream；The starting electric signal that relay is sent to reactive power compensation device is to convey reactive power, Ke Yifu to power grid
It helps power grid to restore as early as possible, passes through out low-voltage region.
Other feature and advantage of the disclosure will illustrate in the following description, alternatively, Partial Feature and advantage can be with
Deduce from specification or unambiguously determine, or by implement the disclosure above-mentioned technology it can be learnt that.
To enable the above objects, features and advantages of the present invention to be clearer and more comprehensible, better embodiment is cited below particularly, and match
Appended attached drawing is closed, is described in detail below.
Detailed description of the invention
It, below will be to specific in order to illustrate more clearly of disclosure specific embodiment or technical solution in the prior art
Embodiment or attached drawing needed to be used in the description of the prior art be briefly described, it should be apparent that, it is described below
Attached drawing is some embodiments of the disclosure, for those of ordinary skill in the art, before not making the creative labor
It puts, is also possible to obtain other drawings based on these drawings.
Fig. 1 is the application scenario diagram for the low voltage crossing that the application embodiment provides；
Fig. 2 is the structure chart for the low voltage ride through system that the application embodiment provides
Fig. 3 is the schematic diagram for the grid-side converter that the application embodiment provides；
Fig. 4 is the wind generator system figure that the application embodiment provides；
Fig. 5 is the low voltage crossing overview flow chart that the application embodiment provides.
Specific embodiment
To keep the purposes, technical schemes and advantages of disclosure embodiment clearer, below in conjunction with attached drawing to this public affairs
The technical solution opened is clearly and completely described, it is clear that and described embodiment is a part of embodiment of the disclosure,
Rather than whole embodiment.Based on the embodiment in the disclosure, those of ordinary skill in the art are not making creation
Property labour under the premise of every other embodiment obtained, belong to the disclosure protection range.
Double-fed fan motor unit realizes that low voltage crossing (Low Voltage Ride Through, LVRT) is wind-power electricity generation neck
An important topic in domain.The application scenario diagram for the low voltage crossing that the application embodiment shown in Figure 1 provides；Its
In include: doubly-fed wind turbine (Doubly Fed Induction Generator, DFIG), resistance-capacitance circuit, resistance-capacitance circuit
Specifically include concatenated resistance R1 and capacitor C1, the switching device in parallel with resistance-capacitance circuit, crowbar circuit, rotor-side converter
RSC and stator side current transformer GSC.
Current transformer protection is that double-fed fan motor unit realizes an important ring during low voltage crossing, when failure is more serious,
Control strategy is limited to Converter Capacity, and crowbar circuit Crowbar becomes simple and effective means, provides for rotor overcurrent
Bypass is to protect current transformer.Crowbar Protect and development so far, all protects current limiting pressure-limiting ability from promotion mostly or reduces crow bar
Investment rear fan is absorbed from power grid it is idle etc. make a search, such as (1) optimization crow bar resistance value and switching time, but no consideration
It is often difficult to take into account the low voltage crossing effect that different voltages fall degree to fixed resistance value；(2) dynamic adjustment crow bar resistive square
Case mainly guarantees that DC bus-bar voltage will not be out-of-limit under various failures, improves the applicability of crow bar protection reply failure,
But it is unobvious to protect making time to shorten, cannot control well blower absorb it is how much idle；(3) Crowbar and control plan
Slightly cooperate, the time of Crowbar investment can be reduced to a certain extent, but control strategy current limitation effect relative resistance is poor, and
And more complicated control algolithm enforcement difficulty is higher；(4) rotor tandem brake resistor proposal, it is also not specific at present to brake resistance value
Setting program is only combined with emulation and determines resistance value, it is difficult to guarantee LVRT effect.
Based on this, the embodiment of the present application proposes a kind of low voltage ride through system, to limit rotor current, auxiliary power grid
Fault recovery, that improves low-voltage passes through performance.It is described in detail below by specific embodiment.
Referring to the structure chart of low voltage ride through system as shown in Figure 2, which includes: relay 21, and with this after
Current transformer 22, first voltage mutual inductor 23 and the switching device 24 that electric appliance 21 is separately connected further include and the switching device
24 resistance-capacitance circuits 25 in parallel, the resistance-capacitance circuit 25 include at least one capacitor element；Wherein,
The current transformer 22 is used to detect the rotor current in objective circuit and the current value that will test is sent to relay
Device 21；
The first voltage mutual inductor 23 is used to detect the voltage of the grid entry point in the objective circuit, and the voltage value that will test
It is sent to relay 21；
The relay 21 is used to be less than predetermined voltage threshold in the voltage value received, and receives the current value and be less than
When predetermined current threshold, disconnection is switched to from closed state to the switching device 24 is triggered with the switching device 24 transmission electric signal
State, so that the resistance-capacitance circuit 25 accesses rotor windings.
Relay 21 sends electric signal to the switching device 24 and triggers the switching device 24 from closed state in above system
Off-state is switched to so that the resistance-capacitance circuit 25 access rotor windings, facilitate the rising for inhibiting the electric current of rotor windings；And
And a capacitor element is included at least in resistance-capacitance circuit 25, capacitor element can send a small amount of reactive power to power grid to assist electricity
Network recovery.
Continue to rise to prevent the electric current of rotor-side, prevention grid condition further deteriorates, which further includes and be somebody's turn to do
The crowbar circuit and second voltage mutual inductor that relay 21 connects；The second voltage mutual inductor is also used to detect in the objective circuit
DC bus-bar voltage, and the d-c bus voltage value that will test is sent to relay 21；
The relay 21 is also used to be greater than the predetermined current threshold in the current value received；Or DC bus electricity
When pressure value is greater than predetermined direct current busbar voltage threshold value, electric signal is sent to the insulated gate bipolar transistor IGBT of the crowbar circuit
So that the rotor windings circuit communication of the crowbar circuit and the objective circuit.
Wherein, crowbar circuit includes resistance and edge grid bipolar transistor IGBT, when IGBT conducting, crowbar circuit connection
Rotor windings circuits, equivalent resistance equivalent to increase rotor windings.To further function as inhibition rotor-side electric current
The effect of rising.
In order to which auxiliary power grid restores as early as possible, which further includes the reactive power compensation device connecting with the relay 21；
When the relay 21 is also used to send electric signal to the insulated gate bipolar transistor IGBT of the crowbar circuit, to this
Reactive power compensation device sends starting electric signal；
Electricity of the reactive power compensation device for starting and being connected to the objective circuit when receiving the starting electric signal
Net conveys reactive power to stablize the voltage of the grid entry point.
Wherein, reactive power compensation device is specifically used to carry out reactive compensation to power grid.By carrying out idle function to power grid
The compensation of rate can help power grid to restore from failure.When it is implemented, reactive power compensation device can use one group of capacitor
It realizes, electric energy has been stored in advance in capacitance group.Capacitance group connects power grid by controllable switching device；When switching device receives
When the electric signal that relay issues, become closed state from off-state, so that capacitance group accesses power grid, is conveyed to power grid
Reactive power.
In order to save cost, reactive power compensation device can also be realized using grid-side converter, because of net side unsteady flow
Device itself can also be completed to send reactive power to power grid.
In preferred embodiments of the present invention, which includes pi regulator, the first input of the pi regulator
End input stator voltage reference value；Second input terminal is connected with the first voltage mutual inductor 23, receives the voltage value of simultaneously network interface；It should
The output end of pi regulator exports q shaft current reference value；The q shaft current reference value is for generating reactive power.Referring to Fig. 3 institute
The schematic diagram for the grid-side converter that the application embodiment shown provides；Including outer voltage and current inner loop: 1) d axis controls:
DC bus-bar voltage reference value Udc_refWith actual value UdcError d shaft current reference value i is exported after PI controllerd_ref；
2) q axis controls: current transformer is in unity power factor operating status, q shaft current reference value i when normal workq_refIt is set as 0, therefore
When barrier process needs current transformer to send reactive power, iq_refBecome by stator voltage reference value ug_refWith actual value ugAfter pass through
It crosses obtained by pi regulator；Then id_ref、iq_refWith corresponding actual value id、iqThe value that error after comparing is exported through PI controller
Again respectively with respective decoupling compensation item ωsiq、ωsidAnd voltage feed-forward control compensation term ugGrid-side converter is obtained after operation
Reference voltage ud_ref、uq_refThree-phase voltage reference component finally can be obtained using coordinate transform, SPWM modulation generates driving letter
Number.
In preferred embodiments of the present invention, if the relay 21 is also used to turn that the current transformer 22 detects
Electron current value is less than predetermined current threshold, sends electric signal so that the crowbar circuit is cut with rotor windings to the IGBT of crowbar circuit
Except separation.
In preferred embodiments of the present invention, which includes resistance, and the resistance and capacitor element series connection connect
It connects.
In preferred embodiments of the present invention, which includes resistance, and the resistance is in parallel with the capacitor element to be connected
It connects.
It include first inside the relay 21 in preferred embodiments of the present invention to illustrate more vividly
Comparator, the second comparator and AND gate circuit；The output end of the first comparator connects the first input end of the AND gate circuit；It should
The output end of second comparator connects the second input terminal of the AND gate circuit；
The first input end of the first comparator is used to receive the voltage value of the first voltage mutual inductor 23 transmission；Second is defeated
Enter end for receiving the predetermined voltage threshold；Compare the size of the voltage value and predetermined voltage threshold received；If connect
The voltage value received is less than the predetermined voltage threshold, and output end exports low level；
The first input end of second comparator is used to receive the current value of the current transformer 22 transmission；Second input terminal
For receiving current threshold；Compare the size of the current value received and predetermined current threshold；If receiving the current value
When less than predetermined current threshold, output end exports low level；
When it is implemented, switching device can be realized with metal-oxide-semiconductor, MOS points are N-type MOS and p-type MOS；In PMOS, G
High level shutdown is connect, low level conducting is connect.Low level is received using the end G of PMOS tube to trigger PMOS tube conducting.
The output end of the AND gate circuit connects the control terminal of the switching device as the output end of the relay 21.
Second aspect, present embodiment provide a kind of wind generator system, including wind-driven generator 41 and low voltage crossing
System 42, the circuit of the wind-driven generator 41 are connect with above-mentioned low voltage ride through system 42.
In order to which the whole flow process of the application, the low-voltage that the application embodiment shown in Figure 5 provides is described in detail
Overall procedure schematic diagram is passed through, specific as follows:
In conjunction with the application scenario diagram of the low voltage crossing in attached drawing 1, Y in figure indicate result judge be it is yes, N indicates to sentence
Disconnected result is no.Doubly-fed wind turbine is when operating normally, switch S0Always it is closed, resistance R1With capacitor C1It is bypassed, R1
And C1It does not access, and capacitor C1On voltage be 0；
After Voltage Drop occurs for grid entry point, rotor current is detectedWith grid entry point voltage Usf；
Judge whether the stator voltage after failure occurs meets Usf≤0.9p.u.；
If it is, disconnecting S0, R1 and C1 is accessed, wherein p.u refers to the voltage rating 690V of double-fed blower；
Judge whether rotor current is suppressed in 1.8IrNBelow；
If it is, continuing to judge rotor current whether below rated value and whether DC bus-bar voltage is in rated value
Below；If rotor current below rated value and DC bus-bar voltage in rated value hereinafter, if cut off concatenated capacitance-resistance electricity
Road；
If not, if rotor current, which persistently rises, is greater than 1.8IrNOr DC bus-bar voltage UdcMore than threshold value Udcmax, sled
Stick circuit Crowbar protection act accesses rotor circuit；Rotor-side converter is out of control, and doubly-fed wind turbine DFIG is in different
Walk operating status；Grid-side converter control model becomes non-unity function from unity power factor operation while Crowbar is put into
The operation of rate factor, to stablize grid entry point voltage as target, adjusts idle output size, slowly certain idle to power grid conveying；
After Crowbar puts into a period of time, judge whether rotor current is less than or equal to 1.8IrN；
If so, excision crowbar circuit Crowbar, and R1And C1Keep concatenation；
Judge whether rotor current is less than or equal to rated value and UdcWhether rated value U is less than or equal todcN；
If rotor current is less than or equal to rated value and DC bus-bar voltage UdcLess than or equal to rated value UdcN, excision string
The R1 and C1 of connection.
The application also proposed series resistance R1, capacitor C1With the setting principle of crowbar resistance, separately below specifically
It is bright:
①R1Setting principle:
Principle 1: investment R1Afterwards, rotor current peak value is less than 1.8IrN；
Principle 2: rotor voltage peak value is less than DC bus-bar voltage threshold value Udcmax。
②C1Setting principle:
Principle 1: the energy that institute's serial capacitors value will ensure to have enough capacity extra when absorbing failure, and reserve certain allowance
Offset the voltage generated after string resistance；
Principle 2: when capacitance voltage minimum, the energy of rotor-side generation when can also absorb failure.
③RcbSetting principle:
Principle 1: at the time of rotor current phase is zero, three-phase symmetrical failure occurs for blower grid entry point and Voltage Drop is
Zero, the peak value of rotor current must not exceed rotor current threshold value I after crow bar resistance is put intormax；
Principle 2: the voltage peak at equivalent crow bar resistance both ends must not exceed DC bus-bar voltage maximum permissible value Udcmax。
Specific setting mode is as described below:
During failure, rotor seals in current transformer continuous service after resistance, the writeable accepted way of doing sth of single-phase rotor current peak (1):
Wherein,For rotor current before failure；Us、UsfFor the stator voltage before and after failure；τr=σ Lr/(Rr+R1) be
Equivalent rotor time constant after access resistance；Rs、RrRespectively stator and rotor resistance parameters； Lr、LsRespectively rotor, stator inductance；Lm
For magnetizing inductance；For leakage inductance coefficient；S is revolutional slip；ωs、ωrRespectively synchronous rotational speed and rotor electric angle
Speed；ω=ωs-ωrFor slip angular velocity；To convert the rotor voltage amplitude for arriving stator side.
Rotor voltage maximum valueAre as follows:
Stator side is converted to obtain:
Wherein, k is the concatenated turn ratio of the every phase winding of stator and rotor.
(1)R1Setting mode:
In the case where failure is relatively light, investment crow bar protection is avoided as far as possible, therefore using Voltage Drop 50% as critical point,
When grid entry point voltage meets U i.e. after failuresf(most critical situation U is taken when >=0.5p.u.sf=0.5p.u.), resistance R1Access
It needs to inhibit fault current in 1.8I after rotorrNBelow, it may be assumed that
From the perspective of double-fed fan operation, rotor accesses resistance suddenly and also belongs to a kind of disturbance, is ensuring current transformer
Small resistance is accessed under the premise of safety can effectively reduce negative effect of the protection circuit to unit, braking resistor R1Value by formula
(5) it can obtain:
R1=R1.min+(R1.max-R1.min) × 30% (5)
R1minIt is the minimum resistance adjusted out, R1maxIt is the maximum resistance adjusted out.
(2)C1Setting mode:
Value requirement as described above, the absorbent energy of capacitor institute are as follows:
Wc=pbase×(0.9-Vmin)×t (6)
VminThe attainable minimum value of stator voltage after the failure of finger.Wherein, pbaseFor double-fed blower rated power；T is electricity
Hold the charging time after accessing.
When three-phase symmetrical short circuit occurs for power grid, rotor fault electric currentIt is sf comprising a DC component, two frequenciess's
Steady-state component and a frequency are (1-s) fsAttenuation components.In order to what is generated when guaranteeing that capacitor has enough energy absorption failures
Energy, it is assumed that the component of both the above frequency is all at the same time to capacitor charging, then capacitor in one cycle fill by possible maximum
The electric time are as follows:
Rotor voltage is when DFIG stable operationWork asMinimum capacity voltage can be obtained, electricity is worked as
When the three-phase ground failure of most serious occurs for net, i.e. rotor open-circuit voltage maximum (Vmin=0), then needed for capacitance are as follows:
Capacitance C can be obtained by formula (6)~(8)1。
(3) crow bar resistance RcbAdjusting:
When grid voltage sags are greater than 50% (Usf< 0.5p.u.) when, if R1It can not limit current in 1.8IrNBelow then
Crowbar circuit is put into, at this time R1With RcbIt accesses simultaneously, crow bar equivalent resistance is R1+Rcb.In order to can press down under in office why hinder
Rotor overcurrent processed, should take three phase short circuit fault the most serious i.e. grid entry point Voltage Drop be 0 the case where.Maximum rotor electric currentA writeable accepted way of doing sth (9):
Wherein,τ after crow bar resistance and series resistance access simultaneouslyrBecome τr=σ Lr/(Rr+
R1+Rcb).Rotor current should be less than in the receptible safe range of rotor-side converter after Crowbar resistance investment, general electric current
Threshold value is 2IrN, and crow bar resistance both end voltage peak value need to be less than DC bus-bar voltage threshold value Udcmax, it may be assumed that
R can be obtained by formula (4), (5)1, R can be obtained in conjunction with formula (9), (10)cbValue range.In order to help power system restoration, also
Including conveying reactive power to power grid to stablize the voltage of grid entry point.It wherein, can be using static state to power grid conveying reactive power
Reactive power compensator realizes that reactive power compensator conveys reactive power to power grid, and power system restoration can be helped normal, walk out low electricity
The region of pressure.
The technical solution of the application can take into account different degrees of Voltage Drop, and when minor failure concatenates capacitance-resistance to limit rotor
Electric current, capacitor not only can absorb excess energy can also issue it is a little idle；Capacitance-resistance of connecting when catastrophe failure and crowbar circuit are simultaneously
Investment, rotor equivalent circuit increase, and improve the effect for inhibiting electric current, effectively reduce investment number and the time of crow bar protection,
It is more resilient to the selection of resistance under this strategy so as to reduce the idle of DFIG absorption；Finally add grid-side converter
Reactive-power control effect, can slowly convey idle to power grid.
More than, the only specific embodiment of the application, but the protection scope of the application is not limited thereto, and it is any to be familiar with
Those skilled in the art within the technical scope of the present application, can easily think of the change or the replacement, and should all cover
Within the protection scope of the application.Therefore, the protection scope of the application should be subject to the protection scope in claims.
Claims (10)
1. a kind of low voltage ride through system characterized by comprising relay, and the electricity being separately connected with the relay
Current transformer, first voltage mutual inductor and switching device further include the resistance-capacitance circuit in parallel with the switching device, the capacitance-resistance
Circuit includes at least one capacitor element；Wherein,
The current transformer is used to detect the rotor current in objective circuit and the current value that will test is sent to relay；
The first voltage mutual inductor is used to detect the voltage of the grid entry point in the objective circuit, and the voltage value hair that will test
Give relay；
The relay is used to be less than predetermined voltage threshold in the voltage value received, and receives the current value and be less than
When predetermined current threshold, disconnection is switched to from closed state to the electric signal triggering switching device is sent with the switching device
State, so that the resistance-capacitance circuit accesses rotor windings.
2. the system as claimed in claim 1, which is characterized in that the system also includes the crow bar connecting with relay electricity
Road and second voltage mutual inductor；The second voltage mutual inductor is also used to detect the DC bus-bar voltage in the objective circuit,
And the d-c bus voltage value that will test is sent to relay；
The relay is also used to be greater than the predetermined current threshold in the current value received；Or the DC bus
When voltage value is greater than predetermined direct current busbar voltage threshold value, the insulated gate bipolar transistor IGBT of Xiang Suoshu crowbar circuit sends electricity
Signal so that the crowbar circuit and the objective circuit rotor windings circuit communication.
3. system as claimed in claim 2, which is characterized in that the system also includes the idle function connecting with the relay
Rate compensation device；
When the relay is also used to send electric signal to the insulated gate bipolar transistor IGBT of the crowbar circuit, Xiang Suoshu
Reactive power compensation device sends starting electric signal；
The reactive power compensation device for receive the starting electric signal when, start and to the objective circuit connection
Power grid conveys reactive power to stablize the voltage of the grid entry point.
4. system as claimed in claim 3, which is characterized in that the reactive power compensation device is grid-side converter.
5. system as claimed in claim 4, the grid-side converter includes pi regulator, the first input of the pi regulator
End input stator voltage reference value；Second input terminal is connected with the first voltage mutual inductor, receives the voltage value of simultaneously network interface；Institute
State the output end output q shaft current reference value of pi regulator；The q shaft current reference value is for generating reactive power.
6. the system as claimed in claim 1, which is characterized in that if the relay is also used to the current transformer detection
The rotor current arrived be less than predetermined current threshold, to the IGBT of crowbar circuit send electric signal so that the crowbar circuit with turn
Sub- winding excision separation.
7. the system as claimed in claim 1, which is characterized in that the resistance-capacitance circuit includes resistance, the resistance and the electricity
Container piece is connected in series.
8. the system as claimed in claim 1, which is characterized in that the resistance-capacitance circuit includes resistance, the resistance and the electricity
Container piece is connected in parallel.
9. the system as claimed in claim 1, which is characterized in that compare inside the relay including first comparator, second
Device and AND gate circuit；The output end of the first comparator connects the first input end of the AND gate circuit；Described second compares
The output end of device connects the second input terminal of the AND gate circuit；
The first input end of the first comparator is used to receive the voltage value that the first voltage mutual inductor is sent；Second input
End is for receiving predetermined voltage threshold；Compare the size of the voltage value and predetermined voltage threshold received；If connect
The voltage value received is less than the predetermined voltage threshold, and output end exports low level；
The first input end of second comparator is used to receive the current value that the current transformer is sent；Second input terminal is used
In reception current threshold；Compare the size of the current value received and predetermined current threshold；If receiving the electric current
When value is less than predetermined current threshold, output end exports low level；
The output end of the AND gate circuit connects the control terminal of the switching device as the output end of the relay.
10. a kind of wind generator system, which is characterized in that including wind-driven generator and such as claim 1-9 any claim
The low voltage ride through system, the circuit of the wind-driven generator are connect with the low voltage ride through system.
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| CN109245173B (en) * | 2018-11-21 | 2024-07-12 | 广东电网有限责任公司 | Low voltage ride through method and system |
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