CN104734596B - A kind of double-fed wind generator machine stator current calculation method with the low ability of wearing - Google Patents

Abstract

A kind of double-fed wind generator machine stator current calculation method with the low ability of wearing, the first operating condition by normally running double-fed wind generator machine under stable state calculate the magnetic linkage size of its rotor；Then the size of the power frequency component of stator current is calculated using the sequence net equivalent circuit under fault condition；The rotor magnetic linkage value of double-fed wind generator machine under failure limit is obtained followed by the result of calculation in power frequency loop；Then rotor magnetic linkage value under normal steady state and failure stable state is brought into the controlled source expression formula for turning frequency electric current, is calculated and is turned frequency component；Finally, by the power frequency component of stator current, turn frequency component and be added with damped alternating current component, obtain last stator current analytical Calculation result；The present invention can provide the analytic solutions of double-fed type fan stator end electric current, so as to carry out the trouble that a large amount of and slow simulation calculation is brought with emulation platform before avoiding, be conducive to scene protection to adjust the carrying out of work.

Description

A kind of double-fed wind generator machine stator current calculation method with the low ability of wearing

Technical field

The present invention relates to Power System Shortcuts computing technique field, and in particular to a kind of double-fed type wind with the low ability of wearing Motor stator current calculation method.

Background technology

New energy (contain intermittent energy) is grid-connected to Operation of Electric Systems and traditional power system theoretical method and skill Art system brings challenges.The short circuit current that generation of electricity by new energy device in weak interconnection region power network containing new energy is provided may More than the short circuit current that system side is provided, when carrying out grid equipment selection, verification and relay protection scheme, adjusting, need to consider Generation of electricity by new energy device influences.Current scene be installed in wind power plant send out circuit protection device occurred in that a lot of malfunctions and The situation of tripping, this case indicates the various protection devices designed based on conventional synchronization machine analysis result can not be good Adapt to the present situation that new energy is accessed, it is therefore desirable to which the transient characterisitics to double-feedback aerogenerator group carry out deep analysis.

On the one hand, double-feedback aerogenerator from phase asynchronous winding motor as generator, itself and conventional synchronization The operation principle of generator is different；On the other hand, due to the introducing of control system and the distinctive Crowbar protections electricity of doubly fed machine The use on road, cause double-feedback aerogenerator under the conditions of grid collapses to system inject short circuit current feature with Conventional synchronization machine has significant difference.Electric system protection device is needed according to the short-circuit voltage of each generating set and electric current Feature is set appropriate definite value or is ensured its correct work using appropriate principle, and then allows power system more Good adapts to the present situation that new energy installation access capacity rapidly increases, it is ensured that its lasting safe and stable operation.Therefore, double-fed is studied The computational methods of formula fan stator electric current for used by scene protect fixed value adjusting work be have very important meaning and significantly Benefit.

The content of the invention

To solve the problems, such as above-mentioned prior art, it is an object of the invention to provide a kind of double-fed with the low ability of wearing Formula wind turbine stator current computational methods, can provide the analytic solutions of double-fed type fan stator end electric current, so as to fortune before avoiding The trouble that a large amount of and slow simulation calculation is brought is carried out with emulation platform, is conducive to scene protection to adjust the carrying out of work.

To reach above-mentioned purpose, the technical solution adopted by the present invention is：

A kind of double-fed wind generator machine stator current calculation method with the low ability of wearing, first by normally running lower pair of stable state The operating condition of feedback formula wind turbine calculates the magnetic linkage size of its rotor；Then using the sequence net equivalent circuit meter under fault condition Calculate the size of the power frequency component of stator current；Followed by double-fed type under the result of calculation acquisition failure limit in power frequency loop The rotor magnetic linkage value of wind turbine；Then rotor magnetic linkage value under normal steady state and failure stable state is brought into and turns the controlled of frequency electric current In the expression formula of source, calculate and turn frequency component；Finally, by the power frequency component of stator current, turn frequency component and damped alternating current component phase Plus, obtain last stator current analytical Calculation result.

The described double-fed wind generator machine stator current calculation method with the low ability of wearing, comprises the following steps：

Step one：The stable state normally run by double-fed wind generator machine calculates its rotor magnetic linkage, and concrete methods of realizing is as follows：

Obtain the space vector of voltage and current value of the double-fed wind generator machine stator generator terminal before failure generation Motor nameplate is consulted simultaneously obtains its Stator and Rotor Windings resistance R_sWith R_r, equivalent mutual inductance L between rotor_mAnd it is equivalent between rotor Self-induction L_sWith L_rParameter, computing formula is as follows：

In formula,WithThe respectively space vector of rotor magnetic linkage, p is differential operator, ω₁It is synchronous rotor angular frequency Rate, ω_rIt is rotor speed angular frequency, L_sWith L_rThe respectively equivalent self inductance of stator and rotor, L_mIt is equivalent mutual inductance between rotor,WithThe respectively space vector of stator and rotor set end voltage, subscript 0 represents its initial value at 0 moment；

Corresponding under stable situationWithIt is respectively a constant under stator and rotor rotating coordinate system, therefore formula (1), the item with differential operator p in (2) is 0, and known quantity has parameter of electric machine L in this up-to-date style (1), (2), (3) and (4)_m、L_s、 L_r、R_sAnd R_rAnd stator voltage electric current initial valueWith

The rotor magnetic linkage under the conditions of failure presteady state is can obtain by simultaneous formula (1), (2), (3) and (4)With

Step 2：The size of the power frequency component of stator current is calculated using the sequence net equivalent circuit under fault condition, specifically Computational methods are as follows：

Using existing short-circuit current calculation method, the double-fed wind generator machine asynchronous machine impedance after crow bar is put into is public Formula represents, calculating be out of order stable state when power frequency stator and rotor current：Stator current positive-sequence componentStator current negative sequence componentRotor current positive-sequence componentRotor current negative sequence component

Step 3：The rotor magnetic linkage of double-fed type unit under failure limit is obtained using the result of calculation in power frequency loop Value, specific method is as follows：

Stator current positive-sequence component under the failure stable situation that step 2 is calculatedStator current negative sequence componentRotor current positive-sequence componentWith rotor current negative sequence componentBring into formula (3) and formula (4), the stable state that must be out of order feelings Rotor magnetic linkage under condition：Stator magnetic linkage positive-sequence componentStator magnetic linkage negative sequence componentRotor flux positive-sequence componentRotor flux negative sequence component

Step 4：Rotor magnetic linkage value under normal steady state and failure stable state is brought into the controlled source expression formula for turning frequency electric current In, calculating and turn frequency component, specific method is as follows：

By formula (3) and (4) simultaneous, obtain：

In formula, It is stator short circuit current,Turn frequency component for rotor current；

Formula (5) is brought into formula (1), (2), is obtained：

If the characteristic value of coefficient matrix is λ in formula (6)₁、λ₂, corresponding characteristic vector isSolve Formula (6) differential equation group, can obtain stator short circuit current expression formula is：

In formula,It is stator short circuit current,It is to turn frequency component initial value in stator short circuit current,It is stator short circuit electricity Attenuating dc component initial value in stream.Coefficient d_s、d_r、c_sAnd c_rAsked by formula (10)；

In formula,The positive-sequence component of stator magnetic linkage during for failure stable state,The negative phase-sequence of stator magnetic linkage during for failure stable state Component,The positive-sequence component of rotor flux during for failure stable state,The negative sequence component of rotor flux during for failure stable state, WithIt is the process variable in solving, r without practical significance₁With r₂Respectively the of two unit characters of formula (6) differential equation vector One value；

Step 5：Turn frequency component and try to achieve stator short circuit current according to step 2 gained power frequency stator current and step 4 gainedSpecific method is as follows：

In formula, τ_sWith τ_rRespectively double-fed type fan stator and rotor damping time constant, are the parameters of electric machine.

Compared with existing simulation means, the invention has the advantages that：

1) avoid and large-scale wind power access system short circuit current was calculated using computer off-line simulation in the past, and use public Formula is calculated, so as to save the plenty of time.

2) the short circuit calculation current expression for being given clearly is understood, to relay protection setting work with foundation.

Brief description of the drawings

Fig. 1 is the inventive method calculation process block diagram.

Fig. 2 is the structure chart of double-fed type blower fan access system.

Specific embodiment

The present invention is described in further details with reference to the accompanying drawings and examples.

Fig. 2 show the structure chart of double-feedback aerogenerator access system.Systematic parameter is as follows：

Double-fed blower fan：Rated capacity 1.5MW, rated voltage 690V, rated frequency 50Hz；Rotor turn ratio 0.3663, Stator impedance Rs+jXs=0.011+j0.1 rotor impedance Rr+jXr=0.009+j0.144, rotor mutual inductance Xm=5.896；Turn Dynamic inertia time constant TJ=3.6s.Wherein all resistance and reactance are the perunit using unit itself rated value as benchmark Value.Crow bar resistance.Rated wind speed 10m/s.Blower fan steady state operating condition：Wind speed 12m/s, wind-driven generator operates in rotating speed Under the operating mode of 1.2pu.

System side equivalent power supply is ideal source.

Connection impedance：RL=0.0001pu, XL=0.001pu.

As shown in figure 1, the present invention is comprised the following steps：

Step one：The stable state normally run by double-fed type asynchronous machine calculates its rotor magnetic linkage.

Obtain the space vector of voltage and current value of the double-fed type asynchronous generator stator generator terminal before failure generationKnown to remaining motor nameplate parameter.Substitute into below equation and calculate normal operation stable state rotor magnetic linkage：

In formula,WithThe respectively space vector of rotor magnetic linkage, p is differential operator, ω₁It is synchronous rotor angular frequency Rate, ω_rIt is rotor speed angular frequency.

Corresponding under stable situationSimultaneous formula (1), (2), (3) and (4) can be solved and is out of order Rotor magnetic linkage under the conditions of presteady stateWith

Step 2：The size of the power frequency component of stator current is calculated using the sequence net equivalent circuit under fault condition.

Using existing short-circuit current calculation method, the double-fed wind generator machine asynchronous machine impedance after crow bar is put into is public Formula represents, calculating be out of order stable state when power frequency stator and rotor current：Stator current positive-sequence componentStator current negative sequence componentRotor current positive-sequence componentRotor current negative sequence component

Step 3：The rotor magnetic linkage of double-fed type unit under failure limit is obtained using the result of calculation in power frequency loop Value, specific method is as follows：

Stator current under the failure stable situation that step 2 is calculatedAnd rotor currentBring into In formula (3) and formula (4), the rotor magnetic linkage under the stable situation that must be out of order：Stator magnetic linkage positive-sequence componentStator magnetic linkage is born Order componentsRotor flux positive-sequence componentRotor flux negative sequence component

Step 4：Rotor magnetic linkage value under normal steady state and failure stable state is brought into the controlled source expression formula for turning frequency electric current In, calculating and turn frequency component, specific method is as follows：

By formula (3) and (4) simultaneous, obtain：

In formula, It is stator short circuit current,Turn frequency component for rotor current；

Formula (5) is brought into formula (1), (2), is obtained：

If the characteristic value of coefficient matrix is λ in formula (6)₁、λ₂, corresponding characteristic vector isSolve Formula (6) differential equation group, can obtain stator short circuit current expression formula is：

In formulaIt is to turn frequency component initial value in stator short circuit current,It is the attenuating dc component in stator short circuit current Initial value.Coefficient d_s、d_r、c_sAnd c_rAsked by formula (10).

In formula,The positive-sequence component of stator magnetic linkage during for failure stable state,The negative phase-sequence of stator magnetic linkage during for failure stable state Component,The positive-sequence component of rotor flux during for failure stable state,The negative sequence component of rotor flux during for failure stable state, WithIt is the process variable in solving, r without practical significance₁With r₂Respectively the of two unit characters of formula (6) differential equation vector One value；

Step 5：Turn frequency component and try to achieve stator short circuit current according to step 2 gained power frequency stator current and step 4 gainedSpecific method is as follows：

In formula, τ_sWith τ_rRespectively double-fed type fan stator and rotor damping time constant, are the parameters of electric machine.

Each AC compounent simulation value of stator short circuit current and analytic value being calculated by above-mentioned steps are to the such as institute of table 1 Show.

The stator short circuit current AC compounent simulation value of table 1 and analytic value

It can be seen that, the calculated value of each composition with simulation value closely, demonstrates the fault current parsing for proposing herein The validity of computational methods.

Claims (1)

1. a kind of double-fed wind generator machine stator current calculation method with the low ability of wearing, first by normally running double-fed under stable state The operating condition of formula wind turbine calculates the magnetic linkage size of its rotor；Then calculated using the sequence net equivalent circuit under fault condition The size of the power frequency component of stator current；Followed by double-fed type wind under the result of calculation acquisition failure limit in power frequency loop The rotor magnetic linkage value of motor；Then into rotor magnetic linkage value under normal steady state and failure stable state is brought the controlled source for turning frequency electric current In expression formula, calculate and turn frequency component；Finally, by the power frequency component of stator current, turn frequency component and be added with damped alternating current component, Obtain last stator current analytical Calculation result；It is characterized in that：Comprise the following steps：

Step one：The stable state normally run by double-fed wind generator machine calculates its rotor magnetic linkage, and concrete methods of realizing is as follows：

Obtain the space vector of voltage and current value of the double-fed wind generator machine stator generator terminal before failure generation Look into simultaneously Read motor nameplate and obtain its Stator and Rotor Windings resistance R_sWith R_r, equivalent mutual inductance L between rotor_mAnd equivalent self inductance L between rotor_s With L_rParameter, computing formula is as follows：

${\stackrel{\·}{U}}_{s0}=R_s{\stackrel{\·}{I}}_{s0}+p{\stackrel{\·}{\mathrm{\ψ}}}_s-{\mathrm{j\ω}}_1{\stackrel{\·}{\mathrm{\ψ}}}_s---\left(1\right)$

${\stackrel{\·}{U}}_{r0}=R_r{\stackrel{\·}{I}}_{r0}+p{\stackrel{\·}{\mathrm{\ψ}}}_r-{\mathrm{j\ω}}_r{\stackrel{\·}{\mathrm{\ψ}}}_r---\left(2\right)$

${\stackrel{\·}{\mathrm{\ψ}}}_{s0}=L_s{\stackrel{\·}{I}}_{s0}+L_m{\stackrel{\·}{I}}_{r0}---\left(3\right)$

${\stackrel{\·}{\mathrm{\ψ}}}_{r0}=L_r{\stackrel{\·}{I}}_{r0}+L_m{\stackrel{\·}{I}}_{s0}---\left(4\right)$

In formula,WithThe respectively space vector of rotor magnetic linkage, p is differential operator, ω₁It is synchronous rotor angular frequency, ω_r It is rotor speed angular frequency, L_sWith L_rThe respectively equivalent self inductance of stator and rotor, L_mIt is equivalent mutual inductance between rotor,With The respectively space vector of stator and rotor set end voltage, subscript 0 represents its initial value at 0 moment；

Corresponding under stable situationWithIt is respectively a constant under stator and rotor rotating coordinate system, therefore formula (1), (2) item with differential operator p in is 0, and known quantity has parameter of electric machine L in this up-to-date style (1), (2), (3) and (4)_m、L_s、L_r、 R_sAnd R_rAnd stator voltage electric current initial valueWith

The rotor magnetic linkage under the conditions of failure presteady state is can obtain by simultaneous formula (1), (2), (3) and (4)With

Step 2：The size of the power frequency component of stator current is calculated using the sequence net equivalent circuit under fault condition, it is specific to calculate Method is as follows：

Using existing short-circuit current calculation method, the double-fed wind generator machine asynchronous machine formula of impedance table after crow bar is put into Show, calculate power frequency stator and rotor current when being out of order stable state：Stator current positive-sequence componentStator current negative sequence componentTurn Electron current positive-sequence componentRotor current negative sequence component

Step 3：The rotor magnetic linkage value of double-fed type unit under failure limit is obtained using the result of calculation in power frequency loop, Specific method is as follows：

Stator current positive-sequence component under the failure stable situation that step 2 is calculatedStator current negative sequence componentTurn Electron current positive-sequence componentWith rotor current negative sequence componentBring into formula (3) and formula (4), under the stable situation that must be out of order Rotor magnetic linkage：Stator magnetic linkage positive-sequence componentStator magnetic linkage negative sequence componentRotor flux positive-sequence componentRotor Magnetic linkage negative sequence component

Step 4：Rotor magnetic linkage value under normal steady state and failure stable state is brought into the controlled source expression formula for turning frequency electric current, is counted Calculate and turn frequency component, specific method is as follows：

By formula (3) and (4) simultaneous, obtain：

$\left\{\begin{array}{c}{\stackrel{\·}{I}}_s=\frac{{\stackrel{\·}{\mathrm{\ψ}}}_s}{L_s^{\′}}-\frac{L_m{\stackrel{\·}{\mathrm{\ψ}}}_r}{L_r{L}_s^{\′}}\\ {\stackrel{\·}{I}}_r=\frac{{\stackrel{\·}{\mathrm{\ψ}}}_r}{L_r^{\′}}-\frac{L_m{\stackrel{\·}{\mathrm{\ψ}}}_s}{L_s{L}_r^{\′}}\end{array}\right.---\left(5\right)$

In formula, It is stator short circuit current,Turn frequency component for rotor current；

Formula (5) is brought into formula (1), (2), is obtained：

$\frac{d}{dt}\left[\begin{array}{c}{\stackrel{\·}{\mathrm{\ψ}}}_s\\ {\stackrel{\·}{\mathrm{\ψ}}}_r\end{array}\right]=\left[\begin{array}{cc}-\frac{R_s}{L_s^{\′}}& \frac{R_s{L}_m}{L_s^{\′}{L}_r}\\ \frac{R_r{L}_m}{L_r^{\′}{L}_s}& -\frac{R_r}{L_r^{\′}}+{\mathrm{j\ω}}_r\end{array}\right]\left[\begin{array}{c}{\stackrel{\·}{\mathrm{\ψ}}}_s\\ {\stackrel{\·}{\mathrm{\ψ}}}_r\end{array}\right]+\left[\begin{array}{c}{\stackrel{\·}{U}}_s\\ {\stackrel{\·}{U}}_r\end{array}\right]---\left(6\right)$

If the characteristic value of coefficient matrix is λ in formula (6)₁、λ₂, corresponding characteristic vector isSolution formula (6) Differential equation group, can obtain stator short circuit current expression formula is：

${\stackrel{\·}{I}}_s={\stackrel{\·}{I}}_{sde}{e}^{{\mathrm{\λ}}_{1}t}+{\stackrel{\·}{I}}_{st}{e}^{{\mathrm{\λ}}_{2}t}+{\stackrel{\·}{I}}_{ss1}{e}^{{\mathrm{j\ω}}_{1}t}+{\stackrel{\·}{I}}_{ss2}{e}^{-{\mathrm{j\ω}}_{1}t}---\left(7\right)$

${\stackrel{\·}{I}}_{st}=\frac{1}{L_s}(d_s{\stackrel{\·}{\mathrm{\ψ}}}_{s0}-\frac{L_m}{L_r}{d}_r{\stackrel{\·}{\mathrm{\ψ}}}_{r0})---\left(8\right)$

${\stackrel{\·}{I}}_{sdc}=\frac{1}{L_s^{\′}}(c_s{\stackrel{\·}{\mathrm{\ψ}}}_{s0}-\frac{L_m}{L_r}{c}_r{\stackrel{\·}{\mathrm{\ψ}}}_{r0})---\left(9\right)$

In formula,It is stator short circuit current,It is to turn frequency component initial value in stator short circuit current,In being stator short circuit current Attenuating dc component initial value；Coefficient d_s、d_r、c_sAnd c_rAsked by formula (10)；

$\left\{\begin{array}{c}{\stackrel{\·}{\mathrm{\ψ}}}_{si}={\stackrel{\·}{\mathrm{\ψ}}}_{s0}-{\stackrel{\·}{\mathrm{\ψ}}}_{ss1}-{\stackrel{\·}{\mathrm{\ψ}}}_{ss2}\\ {\stackrel{\·}{\mathrm{\ψ}}}_{ri}={\stackrel{\·}{\mathrm{\ψ}}}_{r0}-{\stackrel{\·}{\mathrm{\ψ}}}_{rs1}-{\stackrel{\·}{\mathrm{\ψ}}}_{rs2}\\ d_s=\frac{r_2(r_1{\stackrel{\·}{\mathrm{\ψ}}}_{ri}-{\stackrel{\·}{\mathrm{\ψ}}}_{si})}{(r_1-r_2){\stackrel{\·}{\mathrm{\ψ}}}_{s0}}\\ d_r=\frac{r_1{\stackrel{\·}{\mathrm{\ψ}}}_{ri}-{\stackrel{\·}{\mathrm{\ψ}}}_{si}}{(r_1-r_2){\stackrel{\·}{\mathrm{\ψ}}}_{r0}}\\ c_s=\frac{r_1({\stackrel{\·}{\mathrm{\ψ}}}_{si}-r_2{\stackrel{\·}{\mathrm{\ψ}}}_{ri})}{(r_1-r_2){\stackrel{\·}{\mathrm{\ψ}}}_{s0}}\\ c_r=\frac{{\stackrel{\·}{\mathrm{\ψ}}}_{si}-r_2{\stackrel{\·}{\mathrm{\ψ}}}_{ri}}{(r_1-r_2){\stackrel{\·}{\mathrm{\ψ}}}_{r0}}\end{array}\right.---\left(10\right)$

In formula,The positive-sequence component of stator magnetic linkage during for failure stable state,The negative sequence component of stator magnetic linkage during for failure stable state,The positive-sequence component of rotor flux during for failure stable state,The negative sequence component of rotor flux during for failure stable state,WithNothing Practical significance is the process variable in solving, r₁With r₂Respectively formula (6) differential equation two first of unit character vector is worth；

Step 5：Turn frequency component and try to achieve stator short circuit current according to step 2 gained power frequency stator current and step 4 gainedTool Body method is as follows：

${\stackrel{\·}{I}}_s={\stackrel{\·}{I}}_{ss1}+{\stackrel{\·}{I}}_{ss2}+{\stackrel{\·}{I}}_{st}{e}^{-{\mathrm{\τ}}_{r}t}+{\stackrel{\·}{I}}_{sdc}{e}^{-{\mathrm{\τ}}_{s}t}---\left(11\right)$

In formula, τ_sWith τ_rRespectively double-fed type fan stator and rotor damping time constant, are the parameters of electric machine.