CN204497729U - A kind of active Crowbar protective device for wind power generation - Google Patents

Abstract

The utility model relates to applied power electronics technical field, a kind of active Crowbar protective device for wind power generation, comprise by diode D1, D2, D3, D4, D5, the uncontrollable rectifier bridge G of D6 composition, by resistance R1, R2, R3 forms three-phase bleeder resistance Rc, by inductance L 1, L2, L3 form three-phase release inductance Lc and controllable devices IGBT pipe, described diode D1, D3, D5 positive pole respectively with diode D2, D4, D6 negative pole connects, its three nodes are respectively by by resistance R1, inductance L 1, resistance R2, inductance L 2, resistance R3, inductance L 3 is connected with the rotor of double feedback electric engine DFIG after connecting, described diode D1, D3, the negative pole of D5, diode D2, D4, the positive pole of D6 respectively with the collector electrode of controllable devices IGBT pipe, emitter is connected.The utility model adopts the version of resistance, inductance series connection to replace single electric resistance structure form conventional in existing Crowbar; its structure is simple, cost is low, and having can solve again resistance in traditional Crowbar protective circuit cannot the problem of self adaptation different rotating speeds.

Description

A kind of active Crowbar protective device for wind power generation

Technical field

The utility model relates to a kind of active Crowbar protective device for wind power generation, belongs to applied power electronics technical field.

Background technology

Along with the continuous increase of installed capacity of wind-driven power, blower fan off-grid accident frequently occurs, therefore, new network planning requires when grid voltage sags, wind power generation function is not off-grid operation as traditional thermoelectricity, hydroelectricity generator, and provide certain reactive power to electrical network, support power system restoration, until line voltage recovers.Wind turbines especially double-feedback aerogenerator group low voltage ride-through function because its to realize difficulty large, and checking difficulty, has become the emphasis that wind energy turbine set is paid close attention to.But the transformation of what wherein difficulty was maximum the is low voltage ride-through capability of double-fed frequency converter, because double-fed frequency converter rated capacity is little, usually 1/2 ~ 1/3 of unit capacity is only had, so tolerate the ability of the large transient current that grid voltage change produces, mostly countermeasure domestic is at present the method adopting Crowbar bypass, namely when the heavy current impact falling because of set end voltage or recover to produce being detected, drop into Crowbar, by rotor windings short-circuit, for rotor field energy and rotor current provide the passage of consumption and afterflow, avoid transient current to the impact of frequency converter.The patent of typical Crowbar circuit if number of patent application is 201010266619.9 proposes a kind of crowbar circuit of low voltage crossing, the auxiliary circuit that the Crowbar circuit of low voltage crossing of its invention comprises at least a set of main thyristor and is made up of auxiliary triode thyristor, electric capacity and reactor, main thyristor and auxiliary circuit together realize turning on and off of crowbar circuit; The Preservation tactics of the flow-restriction mainly Crowbar equipment of this employing rotor windings that this invention proposes is widely used; namely when there is Voltage Drop; drop into Crowbar holding circuit; by rotor windings short-circuit; for rotor field energy and rotor current provide the passage of consumption and afterflow, avoid transient current to the impact of frequency converter.In order to realize controlled shutoff, Crowbar circuit has the modified model thyristor described in above-mentioned patent or the full structure controlling device of diode rectifier bridge series connection usually, is cut out when needs the normal operating condition recovering motor at any time.The protected mode of this low voltage crossing because realize simple, and is not normally run system and is had an impact, and is therefore widely used.But difficult point is the selection of bleeder resistance.Because the bleeder resistance selected will ensure that its dividing potential drop is unlikely to too high in transient process on the one hand, to such an extent as to exceedes dc-link capacitance withstand voltage, cause dc-link capacitance to damage, therefore need bleeder resistance smaller as far as possible.In addition on the one hand, in order to ensure the effect of releasing, still can cut out from transient state smoothly after transient process terminates when large-slip runs, need motor after large-slip series connection Crowbar resistance during asynchronous operation steady-state current smaller as far as possible, just need Crowbar resistance a little relatively large thus.Therefore, the selection of resistance needs the operation slippage taking into account motor as far as possible, therefore, often selects Crowbar resistance according to worst slippage state, to ensure the realization of low voltage crossing, and often sacrifice like this some so not severe when low voltage crossing effect.

Summary of the invention

In order to overcome the deficiencies in the prior art, the utility model object is to provide a kind of active Crowbar protective device for wind power generation.This protective device adopts the version of resistance, inductance series connection to replace single electric resistance structure form conventional in existing Crowbar; its structure is simple; cost is low, and having can solve again resistance in traditional Crowbar protective circuit cannot the problem of self adaptation different rotating speeds.

In order to realize foregoing invention object, solve problem existing in prior art, the technical scheme that the utility model is taked is: a kind of active Crowbar protective device for wind power generation, comprises by diode D1, D2, D3, D4, D5, the uncontrollable rectifier bridge G of D6 composition, by resistance R1, R2, R3 forms three-phase bleeder resistance Rc, by inductance L 1, L2, L3 forms three-phase and to release inductance Lc and manage as the controllable devices IGBT of uncontrollable rectifier bridge G rectification output end, and described diode D1 positive pole is connected with diode D2 negative pole, and its node passes through resistance R1, inductance L 1 is connected with the rotor of double feedback electric engine DFIG after connecting, and described diode D3 positive pole is connected with diode D4 negative pole, and its node is by resistance R2, inductance L 2 is connected with the rotor of double feedback electric engine DFIG after connecting, and described diode D5 positive pole is connected with diode D6 negative pole, and its node is by resistance R3, inductance L 3 is connected with the rotor of double feedback electric engine DFIG after connecting, described diode D1, D3, the negative pole of D5 is all connected with the collector electrode of controllable devices IGBT pipe, described diode D2, D4, the positive pole of D6 is all connected with the emitter of controllable devices IGBT pipe.

R1, R2, R3 resistance value in described three-phase bleeder resistance Rc is identical.

L1, L2, L3 inductance value that described three-phase is released in inductance Lc is identical.

The utility model beneficial effect is: a kind of active Crowbar protective device for wind power generation, comprises by diode D1, D2, D3, D4, D5, the uncontrollable rectifier bridge G of D6 composition, by resistance R1, R2, R3 forms three-phase bleeder resistance Rc, by inductance L 1, L2, L3 forms three-phase and to release inductance Lc and manage as the controllable devices IGBT of uncontrollable rectifier bridge G rectification output end, and described diode D1 positive pole is connected with diode D2 negative pole, and its node passes through resistance R1, inductance L 1 is connected with the rotor of double feedback electric engine DFIG after connecting, and described diode D3 positive pole is connected with diode D4 negative pole, and its node is by resistance R2, inductance L 2 is connected with the rotor of double feedback electric engine DFIG after connecting, and described diode D5 positive pole is connected with diode D6 negative pole, and its node is by resistance R3, inductance L 3 is connected with the rotor of double feedback electric engine DFIG after connecting, described diode D1, D3, the negative pole of D5 is all connected with the collector electrode of controllable devices IGBT pipe, described diode D2, D4, the positive pole of D6 is all connected with the emitter of controllable devices IGBT pipe.Compared with the prior art; the utility model adopts the version of resistance, inductance series connection to replace single electric resistance structure form conventional in existing Crowbar; its structure is simple, cost is low, and having can solve again resistance in traditional Crowbar protective circuit cannot the problem of self adaptation different rotating speeds.

Accompanying drawing explanation

Fig. 1 is the utility model circuit diagram.

Fig. 2 is the equivalent electric circuit that double fed electric machine rotor side is short-circuited.

Fig. 3 is the equivalent electric circuit that this active Crowbar is dropped in double fed electric machine rotor side.

Embodiment

Below in conjunction with accompanying drawing, the utility model is described in further detail.

As shown in Figure 1, a kind of active Crowbar protective device for wind power generation, comprises by diode D1, D2, D3, D4, D5, the uncontrollable rectifier bridge G of D6 composition, by resistance R1, R2, R3 forms three-phase bleeder resistance Rc, by inductance L 1, L2, L3 forms three-phase and to release inductance Lc and manage as the controllable devices IGBT of uncontrollable rectifier bridge G rectification output end, and described diode D1 positive pole is connected with diode D2 negative pole, and its node passes through resistance R1, inductance L 1 is connected with the rotor of double feedback electric engine DFIG after connecting, and described diode D3 positive pole is connected with diode D4 negative pole, and its node is by resistance R2, inductance L 2 is connected with the rotor of double feedback electric engine DFIG after connecting, and described diode D5 positive pole is connected with diode D6 negative pole, and its node is by resistance R3, inductance L 3 is connected with the rotor of double feedback electric engine DFIG after connecting, described diode D1, D3, the negative pole of D5 is all connected with the collector electrode of controllable devices IGBT pipe, described diode D2, D4, the positive pole of D6 is all connected with the emitter of controllable devices IGBT pipe.R1, R2, R3 resistance value in described three-phase bleeder resistance Rc is identical, and L1, L2, L3 inductance value that described three-phase is released in inductance Lc is identical.Utility model works principle is as follows:

Double feedback electric engine equation:

${\stackrel{\→}{u}}_s=R_s{\stackrel{\→}{i}}_s+p{\stackrel{\→}{\mathrm{\ψ}}}_s+{\mathrm{j\ω}}_s{\stackrel{\→}{\mathrm{\ψ}}}_s---\left(1\right)$

${\stackrel{\→}{u}}_r=R_r{\stackrel{\→}{i}}_r+p{\stackrel{\→}{\mathrm{\ψ}}}_r+{\mathrm{j\ω}}_{\mathrm{sl}}{\stackrel{\→}{\mathrm{\ψ}}}_r---\left(2\right)$

${\stackrel{\→}{\mathrm{\ψ}}}_s=L_s{\stackrel{\→}{i}}_s+L_m+{\stackrel{\→}{i}}_r---\left(3\right)$

${\stackrel{\→}{\mathrm{\ψ}}}_r=L_m{\stackrel{\→}{i}}_s+L_r+{\stackrel{\→}{i}}_r---\left(4\right)$

In equation, all parameters all convert stator side.

Calculated by formula (3), (4):

${\stackrel{\→}{i}}_s=\frac{1}{L_s-\frac{L_m^2}{L_r}}{\stackrel{\→}{\mathrm{\ψ}}}_s+\frac{L_m}{L_r}\frac{1}{L_s-\frac{L_m^2}{L_r}}{\stackrel{\→}{\mathrm{\ψ}}}_r---\left(5\right)$

${\stackrel{\→}{i}}_r=-\frac{L_m}{L_s}\frac{1}{L_r-\frac{L_m^2}{L_s}}{\stackrel{\→}{\mathrm{\ψ}}}_s+\frac{1}{L_r-\frac{L_m^2}{L_s}}{\stackrel{\→}{\mathrm{\ψ}}}_r---\left(6\right)$

When grid voltage sags, suppose that falling front line voltage is U _s(t ₀), falling rear line voltage is PU _s(t ₀), then the change procedure of stator magnetic linkage is:

The time constant of rotor magnetic linkage DC component decay is:

$T_s^{\′}=\frac{L_s^{\′}}{R_s}$

$T_r^{\′}=\frac{L_r^{\′}}{R_r}$

Magnetic linkage change procedure is:

${\mathrm{\ψ}}_s\left(t\right)={\mathrm{\ψ}}_{\mathrm{sdc}}+{\mathrm{\ψ}}_{\mathrm{sf}}=\frac{(1-p)U_s\left(t_0\right)}{{\mathrm{j\ω}}_s}{e}^{-t/T_s^{\′}}+\frac{{\mathrm{pU}}_s\left(t_0\right)}{{\mathrm{j\ω}}_s}{e}^{j{\mathrm{\ω}}_{s}t}$

Rotor flux:

${\mathrm{\ψ}}_r\left(t\right)={\mathrm{\ψ}}_{\mathrm{rdc}}+{\mathrm{\ψ}}_{\mathrm{rf}}=\frac{(1-p)U_s\left(t_0\right)}{{\mathrm{j\ω}}_s}{e}^{j{\mathrm{\ω}}_{r}t}{e}^{-t/T_r^{\′}}+\frac{{\mathrm{pU}}_s\left(t_0\right)}{{\mathrm{j\ω}}_s}{e}^{j{\mathrm{\ω}}_{s}t}$

Suppose that Voltage Drop is to 0, meets the following conditions simultaneously:

Fall i.e. rotor-side short circuit instantaneously, fall moment double feedback electric engine synchronous speed operation, fall double feedback electric engine instantaneously and operate in rated power point.

Then:

$i_s\left(t\right)==\frac{{\mathrm{\ψ}}_{s0}}{L_{\mathrm{\σ}}}(e^{-t/T_s^{\′}}-e^{j{\mathrm{\ω}}_{s}t}{e}^{-t/T_r^{\′}})$

Wherein: L _σ=L _{σ s}+ L _{σ r}, be rotor leakage inductance sum.

The moment of short circuit, rotor magnetic linkage position angle and amplitude approximately equal, stator magnetic linkage relative stator is static, and rotor flux rotates along with rotor, and after half period, it departs from initial position 180 °, and direction is contrary, and the electric current of motor reaches maximum.So, when not dropping into Crowbar resistance, its equivalent electric circuit as shown in Figure 2:

$i_{s,\max }\≈i_{r,\max }=\frac{{2U}_s}{{\mathrm{\ω}}_s{L}_{\mathrm{\σ}}}$

When dropping into this modified model Crowbar, its equivalent electric circuit as shown in Figure 3:

Stator side equivalent resistance is:

$Z_s\left(s\right)=\frac{s^2{L}_m(L_{\mathrm{\σ}}+L_c)+{\mathrm{sL}}_s{R}_c}{s(L_{\mathrm{\σ}}+L_c)+R_c}$

Rotor-side equivalent resistance:

Z _r(s)＝s(L _σ+L _c)+R _c

So time constant is:

$T_s^{\′}=\frac{R_c^2+{\mathrm{\ω}}_s^2{L}_s(L_{\mathrm{\σ}}+L_c)}{{\mathrm{\ω}}_s^2(L_s-L_{\mathrm{\σ}}-L_c)R_c}$

$T_r^{\′}=\frac{L_{\mathrm{\σ}}+L_c}{R_c}$

Then:

$i_s\left(t\right)\≈{-i}_r\left(t\right)=\frac{{\mathrm{j\ω}}_s{\mathrm{\ψ}}_{s0}{e}^{-t/T_s^{\′}}}{{\mathrm{j\ω}}_s(L_{\mathrm{\σ}}+L_c)+R_c}-\frac{{\mathrm{\ψ}}_{\mathrm{rdc}0}{e}^{-t/T_s^{\′}}}{L_{\mathrm{\σ}}+L_c}{e}^{j{\mathrm{\ω}}_{s}t}{e}^{-t/T_r^{\′}}$ Work as R _ctime larger, T ' _rthan T ' _smuch little, so within the same time interval, the Section 2 in above formula much smaller than Section 1, so, maximum current primarily of in above formula Section 1 determine.So:

$i_{s,\max }\≈i_{r,\max }=\frac{U_s}{\sqrt{{\left({\mathrm{\ω}}_s(L_{\mathrm{\σ}}+L_c\right)}^2+R_c^2}}$

When motor does not run in synchronous speed, but when running within the scope of the slippage of synchronous speed upper and lower 30%, between maximum current and rotating speed, meet such relation:

$i_{s,\max }\≈i_{r,\max }=\frac{{\mathrm{\ω}}_r}{{\mathrm{\ω}}_s}\frac{U_s}{\sqrt{({\mathrm{\ω}}_r(L_{\mathrm{\σ}}+L_c){)}^2+R_c^2}}$

The basic thought realizing low voltage crossing realization is with bleeder resistance R _cwith inductance L of releasing _ccascaded structure replace traditional bleeder resistance, the beneficial effect done like this is as can be seen from the theory analysis of the above-mentioned operation principle based on double feedback electric engine, and after adopting described modified model Crowbar protective circuit structure, the pass of maximum current and rotating speed is like this, in rotational speed omega _rtime larger, the denominator term in relational expression middle L _cthe part of equivalence also can increase, be equal to like this and sealed in larger Crowbar resistance, thus effectively reduce maximum current, reduce the impact to unit, the input again of the excessive Crowbar of causing of leakage current or Crowbar can be avoided again to cut out rear frequency converter and restart overcurrent; Time rotating speed is little, the denominator term in relational expression middle L _cthe part of equivalence also can reduce, and is equal to the Crowbar resistance sealed in so relatively little, can realizes low voltage crossing smoothly like this, be unlikely to again to cause too large impact to unit.

The utility model advantage is: a kind of active Crowbar protective device for wind power generation; the version of resistance, inductance series connection is adopted to replace single electric resistance structure form conventional in existing Crowbar; its structure is simple, cost is low, and having can solve again resistance in traditional Crowbar protective circuit cannot the problem of self adaptation different rotating speeds.

Claims (3)

1., for an active Crowbar protective device for wind power generation, comprise by diode D1, D2, D3, D4, D5, the uncontrollable rectifier bridge G of D6 composition, by resistance R1, R2, R3 forms three-phase bleeder resistance Rc, by inductance L 1, L2, L3 forms three-phase and to release inductance Lc and manage as the controllable devices IGBT of uncontrollable rectifier bridge G rectification output end, and it is characterized in that: described diode D1 positive pole is connected with diode D2 negative pole, its node passes through resistance R1, inductance L 1 is connected with the rotor of double feedback electric engine DFIG after connecting, and described diode D3 positive pole is connected with diode D4 negative pole, and its node is by resistance R2, inductance L 2 is connected with the rotor of double feedback electric engine DFIG after connecting, and described diode D5 positive pole is connected with diode D6 negative pole, and its node is by resistance R3, inductance L 3 is connected with the rotor of double feedback electric engine DFIG after connecting, described diode D1, D3, the negative pole of D5 is all connected with the collector electrode of controllable devices IGBT pipe, described diode D2, D4, the positive pole of D6 is all connected with the emitter of controllable devices IGBT pipe.

2. a kind of active Crowbar protective device for wind power generation according to claim 1, is characterized in that: R1, R2, R3 resistance value in described three-phase bleeder resistance Rc is identical.

3. a kind of active Crowbar protective device for wind power generation according to claim 1, is characterized in that: L1, L2, L3 inductance value that described three-phase is released in inductance Lc is identical.