CN104092421B - A kind of long stator synchronous linear motor drives uses Converter Capacity system of selection - Google Patents

Abstract

The present invention relates to a kind of long stator synchronous linear motor driving Converter Capacity system of selection, comprise the steps: (1) overall project demand according to current high-speed magnetic floating project, it is thus achieved that boundary condition；(2) based on described boundary condition, mileage s is accelerated in the expectation calculating train_m, tractive force F when train will reach maximum speed_xAnd now required stator current I_svmWith voltage U_sm；(3) assume that current transformer output maximum current is I_sm0=I_svm, according to Mathematical Modeling calculate train accelerate when rate curve, it is thus achieved that train work as preacceleration mileage(4) relatively more described when preacceleration mileageAccelerate mileage s with expectation_mSize, the stator current limit value obtaining(6) gained voltage U is calculated by step (2)_smCalculate gained electric current with step (5)Obtain the capacity of required current transformer.Compared with prior art, the present invention have calculating flexibly, result of calculation matching degree advantages of higher.

Description

A kind of long stator synchronous linear motor drives uses Converter Capacity system of selection

Technical field

The present invention relates to high-speed magnetic floating technical field, especially relate to a kind of long stator synchronous linear motor driving unsteady flow Device Capacity Selection method.

Background technology

As the development of domestic industry technical merit and high-power converter design the raising of the level of production, megavolt-ampere level The use of other high-voltage high-power converter is increasingly common.Drive for long stator synchronous linear motor, particularly high speed magnetic The demand of the high-power converter that floating train drives also will be more and more.Have been put into the million of high-speed magnetic floating commercial operation at present The Converter Capacity of volt-ampere rank only has two kinds of ranks of 15MVA and 7.5MVA.With often leading the development of high speed Maglev, according to The demand of different engineering projects, it is likely that require that the current transformer having more power grade is available.And with power grade Increase, expansion is also needed in the standardized work of high-power converter power grade being applied to high speed Maglev badly.So, exist In concrete engineering project, the current transformer needing which kind of capacity is just suitable？In following equipment standard is formulated, should how to make again Determine the capacitance grade of high-power converter to meet the needs of engineering project？

The Capacity Selection of general high-power converter is divided into 3 steps:

(1) understand load characteristic and Changing Pattern, calculate the size of load current or make load current figure I=f (t)。

The selected process of Converter Capacity, actually current transformer and the optimal matching process of motor.For different loads The motor of characteristic, uses different method computational load electric currents:

The calculating of Converter Capacity when-constant load is run continuously: general consideration electric motor starting mode, opening according to motor Streaming current or rated current, determine load current, then the capacity of preliminary election current transformer.

The calculating of Converter Capacity when-cyclically-varying load runs continuously: first make motor load map of current n= Φ (t) and I=f (t), then obtains average load current, then the capacity of preliminary election current transformer.

The calculating of Converter Capacity when-aperiodicity varying duty runs continuously: typically turn in output maximum by motor The rated current of Current calculation current transformer during square.

(2) the capacitance grade preliminary election Converter Capacity according to existing current transformer；

(3) according to overload and startup capability check preliminary election current transformer.

Commercial off-the-shelf is often led high speed Maglev trailer system and is a powerful long stator straight line at present Synchronous motor system, its stator is positioned on track, and rotor is the magnetic-levitation train of high-speed cruising, but is not particularly suited for above-mentioned Universal method.This is because the above-mentioned first step calculates the motor product that current transformer load current is directed to maturation.This A little motor products have corresponding standard termination characteristic, can be calculated by specification or standard or be inquired about.And at a high speed Linear synchronous motor that electromagnetic suspension technology is used the ripe motor product of non-universal.Due to the circuit put into commercial operation at present Only Shanghai demonstration line, the load characteristic of its linear electric motors being used is only applicable to this engineering project of Shanghai line.Directly Line motor output torque capacity when, i.e. train startup stage, its output voltage is relatively low.And the maximum output electricity needed for motor Pressure, then depend on the requirement of maximum speed, line condition and departure interval etc. that train must reach, different engineering projects Between will make a big difference.For following engineering project, probably due to the difference of project demands, and make motor load characteristic Different.

Additionally, put into commercial operation at present, the current transformer that is applicable to high speed Maglev only have 15MVA and 7.5MVA two Planting standard, not only the leeway of preliminary election is limited, cannot guarantee that accurately according to the result that this alternative capacity verifies.If being not limited to Existing capacity, and assume that a certain capacitance grade and parameter carry out tentative calculation verification, it assumes that optional combination is too many, will cause meter Operator workload is relatively big, and efficiency is low, and it cannot be guaranteed that obtains optimal result.

Content of the invention

The purpose of the present invention is contemplated to the defect overcoming above-mentioned prior art to exist, from the angle of high-speed magnetic floating project demands Degree sets out, based on the Mathematical Modeling of linear synchronous generator, it is proposed that a kind of calculate flexibly, the high length of result of calculation matching degree Linear stator synchronous machine drives Converter Capacity system of selection, it is adaptable to high-speed magnetic floating project.The method is not only specifically High-speed magnetic floating project in can obtain reasonably, be applicable to the required entries purpose Converter Capacity and the key such as voltage, electric current Characterisitic parameter, and also can play booster action in the formulation process of production domesticization high-power converter capacitance grade.

The purpose of the present invention can be achieved through the following technical solutions:

A kind of long stator synchronous linear motor drives uses Converter Capacity system of selection, comprises the steps:

(1) the overall project demand according to current high-speed magnetic floating project, it is thus achieved that boundary condition, including speed target value v_m、 Holding acceleration a_b, train maximum marshalling number n and train be in average acceleration a of accelerating sections；

(2) based on described boundary condition, according to the Mathematical Modeling of Newton's second law and long stator synchronous linear motor, Mileage s is accelerated in the expectation calculating train_m, tractive force F when train will reach maximum speed_xAnd now required stator electricity Stream I_svmWith voltage U_sm；

(3) assume that current transformer output maximum current is I_sm0=I_svm, with I_sm0And U_smAs long stator linear synchronous motor Stator current, the limit value of voltage, substitute into long stator synchronous linear motor Mathematical Modeling, it is thus achieved that train work as preacceleration mileage

(4) relatively more described when preacceleration mileageAccelerate mileage s with expectation_mSize, ifIt is more thanIt is fixed then to increase Electron current limit valueOtherwise reduce stator current limit valueΔ I is the current increment setting；

(5) makeRepeat step (3), untilEqual to s_mTill, the stator current limit value now obtainingI.e. For required current transformer maximum output current；

(6) gained voltage U is calculated by step (2)_smCalculate gained electric current with step (5)Obtain the appearance of required current transformer Amount, expression formula is:

$S={3U}_{\mathrm{sm}}{I}_{\mathrm{sm}}^{*}$

Wherein, U_sm、It is respectively phase voltage, the virtual value of phase current.

Described overall project demand includes train minimum departure interval, highest running speed of train, the capacity of train and row The climbing capacity of car.

Say from operation principle, the long stator synchronous linear motor that high-speed magnetic floating is used, its traction control with general Linear synchronized motor is similar to.According to traditional synchronous motor principle, the synchronization of stable state duration linear stator can be obtained electronic The dq Mathematical Modeling of machine.Under orientation on rotor flux strategy, in order to reach the purpose with suspension magnetic decoupling, Linear Synchronous The d shaft current approximation of motor is controlled as zero, and therefore the Mathematical Modeling of described long stator synchronous linear motor includes below equation:

Voltage equation

$\left\{\begin{array}{c}{u}_d=-\frac{\mathrm{\π}}{{\mathrm{\τ}}_s}{\mathrm{vL}}_q{i}_q\\ u_q={\mathrm{Ri}}_q+\frac{\mathrm{\π}}{{\mathrm{\τ}}_s}{\mathrm{vL}}_{\mathrm{sm}}{i}_m\end{array}\right.---\left(1\right)$

$u_d^2+u_q^2=U_s^2---\left(2\right)$

Thrust equation

$F_x=\frac{3}{2}\frac{\mathrm{\π}}{{\mathrm{\τ}}_s}{L}_{\mathrm{sm}}{i}_m{i}_q---\left(3\right)$

Power

$P=\frac{3}{2}{u}_q{i}_q---\left(4\right)$

Motor stator electric current

$I_s=i_q/\sqrt{2}=\frac{-2v\frac{\mathrm{\π}}{{\mathrm{\τ}}_s}{\mathrm{RL}}_{\mathrm{sm}}{i}_m+\sqrt{{\left(2v\frac{\mathrm{\π}}{{\mathrm{\τ}}_s}{\mathrm{RL}}_{\mathrm{sm}}{i}_m\right)}^2-4(R^2+{\left(v\frac{\mathrm{\π}}{{\mathrm{\τ}}_s}{L}_q\right)}^2)({\left(v\frac{\mathrm{\π}}{{\mathrm{\τ}}_s}{L}_{\mathrm{sm}}{i}_m\right)}^2-U_s^2)}}{2\sqrt{2}(R^2+{\left(v\frac{\mathrm{\π}}{{\mathrm{\τ}}_s}{L}_q\right)}^2)}---\left(5\right)$

U in above-mentioned equation_d、u_qFor d, q shaft voltage component of current transformer output, U_sFor linear motor stator electric end input electricity Pressure, L_qFor linear electric motors q axle inductance, L_smFor the mutual inductance of linear motor stator electric winding and Exciting Windings for Transverse Differential Protection, i_qFor linear electric motors q axle electricity Stream, i_mFor exciting current, τ_sFor the pole span of linear electric motors, v is train speed, F_xFor tractive force of train, P is disappeared by linear electric motors The active power of consumption, R is the resistance of linear motor stator electric winding.

According to the Mathematical Modeling of described long stator synchronous linear motor, the ceiling voltage U of the required output of current transformer_smCalculating Process, specific as follows:

A) Negotiation speed desired value v_mWith Holding acceleration a_b, it is calculated train and be up to institute's palpus before maximum speed shortly Tractive force F_x=F_z(v_m)+ma_b, wherein F_z(v_m) represent train in speed v_mUnder resistance, m is the quality of train, by speed It is calculated with the drag characteristic of train；

B) stator current before train reaches maximum speed is obtained according to formula (5)

C) according to average acceleration a and speed target value v_mObtain the actual acceleration distance of train

D) by I_svmAnd s_mThe pressure drop u on feed cable and stator cable can be calculated_σ；

E) by speed target value v_mWith train marshalling list n, back-emf u under maximum speed for the train can be calculated_dpWith u_qp；

F) by u_σ、u_dpAnd u_qpI.e. can get the voltage U that train current transformer when reaching maximum speed is exported_sm。

Described step (3) calculates the rate curve when accelerating for the train, it is thus achieved that train work as preacceleration mileageSpecifically For:

A) basic data according to project initializes linear electric motors parameter, and and I_sm0、U_smAnd s_mTogether as input number According to；

B) motor stator electric current I is calculated according to formula (5)_s；

If c) motor stator electric current I_s≥I_sm0, then I is taken_sm0Calculate as stator current；

D) motor thrust F is calculated according to formula (2)_x；

E) train current acceleration a is calculated according to Newton's second law_x, speed v_xWith displacement s_x；

If f) present speed v_x<v_m, then update linear electric motors parameter according to current displacement and speed, return step a)；

If g) present speed v_x≥v_m, then accelerating sections displacement is exported

Described basic data includes circuit line style data, station and electric substation's position data.

Compared with prior art, the invention have the advantages that

(1) do not limited by existing Converter Capacity, but obtained the border calculating according to the actual demand of engineering project Condition.

(2) with the demand of actual items as starting point, result of calculation is high with the matching of project.

(3) being iterated calculating based on the Mathematical Modeling of long stator synchronous linear motor, computational efficiency is high, calculates knot Fruit is accurately.

(4) computational methods are flexible, it is adaptable to various high-speed magnetic floating projects.Therefore driving for long stator synchronous linear motor During the Standardization Research of dynamic high-power converter, can be as strong aid.

Brief description

Fig. 1 is linear synchronized motor steady-state operation polar plot；

Fig. 2 is the schematic flow sheet of the present invention；

Fig. 3 is train accelerating sections rate curve calculation process；

Fig. 4 is the relation schematic diagram of Holding acceleration and the gradient；

Fig. 5 is the speed of embodiment 1, accelerating curve；

Fig. 6 is the current transformer power curve of embodiment 1；

Fig. 7 is the current transformer voltage of embodiment 1, current curve.

Detailed description of the invention

The present invention is described in detail with specific embodiment below in conjunction with the accompanying drawings.The present embodiment is with technical solution of the present invention Premised on implement, give detailed embodiment and concrete operating process, but protection scope of the present invention be not limited to Following embodiment.

Below as a example by one section of virtual circuit, calculate in this section of circuit according to different engineering project index requests, The capacitance grade of the current transformer that should use respectively.Wherein, linear electric machine traction uses two-step method both end power supplying, and traction subregion is long 40km, stator segment average length 1200m, the marshalling of 5, train, use parameter and the resistance model of Shanghai Maglev.Vehicle Load considers average load (i.e. 80% is fully loaded with).Remaining hypothesis is as follows:

1) cable limit value:

In calculating, the stator current of gained can not be more than the threshold value of cable overcurrent protection, and stator terminal voltage is the highest can not be surpassed Cross the pressure grade of stator cable.Actual threshold value should determine according to the cable model that detailed programs are used with pressure grade. Below in an example, it is assumed that stator current overcurrent protection threshold value is 2000A, pressure for 20kV line voltage.

2) Holding acceleration before train reaches maximal rate:

In view of the stronger acceleration capacity of high-speed maglev train, Holding acceleration adopted here is with reference to " train traction Calculate code " in the value of defined, take 0.15m/s temporarily²And 0.2m/s²It is respectively calculated.

The value of Holding acceleration is directly related with climbing capacity under highest running speed for the train.As shown in Figure 4, false If a_bFor Holding acceleration, the quality of train is m, and the gradient of circuit is θ, and acceleration of gravity is g, and F is that train is at level tangent track On overcome the free tractive force after resistance, then have F=ma_b.Weight component mg θ phase when the F of train goes up a slope with train Deng when, it is ensured that train keeps highest running speed to run on this ramp.Now have

${\mathrm{ma}}_b=\mathrm{mg\&theta;}\&DoubleRightArrow;a_b=\mathrm{g\&theta;}$

Understand Holding acceleration a from above formula_bCan guarantee that to train ruling grade θ of highest running speed is directly proportional, differ g Times.

3) average acceleration of accelerating sections: 0.4m/s²And 0.5m/s²。

4) target velocity grade: 400km/h, 500km/h.

According to above-mentioned it is assumed that will calculate according to three kinds of situations shown in table 1 table below.

The input parameter of table 1 embodiment

(1) embodiment 1:

1) according to target velocity, average acceleration and step as shown in Figure 2, the acceleration mileage s of train is calculated_m= 15432m, train will reach tractive force F during maximum speed_x≈ 142256N, and now required stator current I_svm= 590A。

2) it is illustrated in figure 1 linear synchronized motor steady-state operation polar plot, wherein, when the stator terminal of linear electric motors applies Cosinusoidal voltage U_sWhen, phase angle is β, and d, q shaft voltage can be expressed as

$\left\{\begin{array}{c}{u}_d={-U}_s\sin \mathrm{\&beta;}\\ u_q=U_s\cos \mathrm{\&beta;}\end{array}\right.$

Therefore, voltage when train will reach target velocity is calculatedWherein, u_d =-4.78kV, u_q=6.71kV, U_smFor phase voltage virtual value.

3) by above-mentioned I_svm、U_smAnd s_mSubstitute into workflow management train shown in Fig. 3 and accelerate mileage, by result of calculationWith s_mEnter Row compares.WhenWhen, speed as shown in Figure 5 and accelerating curve can be obtained, now $I_{\mathrm{sm}}^{*}=0.625\mathrm{kA}.$

The result of calculation of embodiment 1 collects to table 2, and in table, Converter Capacity presses formulaCalculate.Result of calculation Show, in the engineering project of embodiment 1, as long as the current transformer using capacity to be 11MVA can meet engineering demand.This time-varying The highest phase voltage of stream device output is less than 6kV.According to this result of calculation, concrete engineering can use corresponding electricity Cable and equipment, beneficially cost saving.

Table 2 embodiment 1 Converter Capacity result of calculation

Fig. 5 is the speed of embodiment 1, acceleration-position curve.Wherein, solid line is rate curve, and dotted line is that acceleration is write music Line.Visible, when speed is relatively low, the acceleration peak of train is up to 0.74m/s², target velocity 400km/h will be reached Moment, acceleration still has 0.15m/s²(meeting Holding acceleration is 0.15m/s²Condition).

Fig. 6 is the active power curves of current transformer output in embodiment 1.Owing to have employed both end power supplying, at the two of subregion End is respectively arranged a traction substation, and Mei Zuo electric substation respectively configures one group of current transformer to this switched-mode power supply.Therefore Fig. 5 has two Bar power curve, wherein solid line represents the power (next stop power) that the traction near starting point becomes, and dotted line represents near terminal traction The power (power of standing afterwards) becoming, Grey curves is train speed.In figure two traction become peak power occur in different in Journey position, this is owing to have employed the method by mileage distribution electric current.In Fig. 6, peak power is not present in train and is i.e. up to Before maximum speed, this explanation is not wasted by the calculated Converter Capacity of methods described herein.If Converter Capacity Surplus is bigger, then the peak value of power will appear in the position reaching maximum speed closer to train.

Fig. 7 show the current transformer voltage after embodiment 1 calculates, current curve.Q axle electricity after wherein electric current is dq conversion Stream, corresponding with the peak value of actual stator electric current.It can be seen that before reaching target velocity in a flash, both-end unsteady flow The voltage of device has reached peak value 5.83kV all, and double-ended current sum is I_svm=590A (virtual value).But double-ended current is not With, distance train is big compared with near next stop output current of converter, and the rear station output current of converter that distance train is farther out is little, this It is also due to cause by the control method of mileage distribution electric current.In addition, as can be seen from Figure 7, when train will reach target velocity, When not being current transformer output maximum current.This is also why to need to be iterated calculatingThe reason.

(2) embodiment 2 and embodiment 3:

Meet embodiment 2 and the Converter Capacity result of calculation of embodiment 3 is as shown in table 1.Concrete simulation curve and Fig. 5 ～Fig. 7 is similar to, and repeats no more here.As known from Table 1,15MVA high power current transformer is used substantially can to meet wanting of embodiment 2 Ask.But it is it desired to improve the acceleration capacity of train and climbing capacity to the level of embodiment 3, then need more high power capacity grade Current transformer, about 21MVA.This is because the increase of acceleration capacity requires that the current output capability of current transformer also to increase accordingly. The operation time ratio making train is used embodiment 2 to shorten about 20 seconds by the current transformer using embodiment 3.

The Converter Capacity result of calculation of table 3 embodiment 2 and 3

Claims (4)

1. a long stator synchronous linear motor drives and uses Converter Capacity system of selection, it is characterised in that comprise the steps:

(1) the overall project demand according to current high-speed magnetic floating project, it is thus achieved that boundary condition, including speed target value v_m, possess and add Speed a_b, train maximum marshalling number n and train be in the average acceleration of accelerating sectionsDescribed overall project demand includes train The climbing capacity of little departure interval, highest running speed of train, the capacity of train and train；

(2) based on described boundary condition, according to the Mathematical Modeling of Newton's second law and long stator synchronous linear motor, calculate Mileage s is accelerated in the expectation of train_m, tractive force F when train will reach maximum speed_xAnd now required stator current I_svm With voltage U_sm；

(3) assume that current transformer output maximum current is I_sm0=I_svm, with I_sm0And U_smAs long stator linear synchronous motor stator Electric current, the limit value of voltage, the Mathematical Modeling substituting into long stator synchronous linear motor calculates the rate curve when accelerating for the train, obtains Obtain train works as preacceleration mileage

(4) relatively more described when preacceleration mileageAccelerate mileage s with expectation_mSize, ifIt is more thanThen increase stator current Limit valueOtherwise reduce stator current limit valueΔ I is the current increment setting；

(5) makeRepeat step (3), untilEqual to s_mTill, the stator current limit value now obtainingIt is required The current transformer maximum output current wanted；

(6) gained voltage U is calculated by step (2)_smCalculate gained electric current with step (5)Obtain the capacity of required current transformer, table Reaching formula is:

$S=3U_{sm}{I}_{sm}^{*}$

Wherein, U_sm、It is respectively phase voltage, the virtual value of phase current.

2. a kind of long stator synchronous linear motor driving Converter Capacity system of selection according to claim 1, it is special Levying and being, the Mathematical Modeling of described long stator synchronous linear motor includes below equation:

Voltage equation

$\left\{\begin{array}{c}{u}_d=-\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_s}{\mathrm{vL}}_q{i}_q\\ u_q={\mathrm{Ri}}_q+\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_s}{\mathrm{vL}}_{sm}{i}_m\end{array}\right.$

$U_s=\sqrt{u_d^2+u_q^2}$

Thrust equation

$F_x=\frac{3}{2}\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_s}{L}_{sm}{i}_m{i}_q$

Power

$P=\frac{3}{2}{u}_q{i}_q$

Motor stator electric current

$I_s=i_q/\sqrt{2}=\frac{-2v\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_s}{\mathrm{RL}}_{sm}{i}_m+\sqrt{{\left(2v\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_s}{\mathrm{RL}}_{sm}{i}_m\right)}^2-4(R^2+{\left(v\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_s}{L}_q\right)}^2)({\left(v\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_s}{L}_{sm}{i}_m\right)}^2-U_s^2)}}{2\sqrt{2}(R^2+{\left(v\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_s}{L}_q\right)}^2)}$

U in above-mentioned equation_d、u_qFor d, q shaft voltage component of current transformer output, U_sFor linear motor stator electric end input voltage, L_q For linear electric motors q axle inductance, L_smFor the mutual inductance of linear motor stator electric winding and Exciting Windings for Transverse Differential Protection, i_qFor linear electric motors q shaft current, i_m For exciting current, τ_sFor the pole span of linear electric motors, v is train speed, F_xFor tractive force of train, P is having that linear electric motors are consumed Work(power, R is the resistance of linear motor stator electric winding.

3. a kind of long stator synchronous linear motor driving Converter Capacity system of selection according to claim 2, it is special Levy and be, described step (3) calculates the rate curve when accelerating for the train, it is thus achieved that train work as preacceleration mileageSpecifically For:

A) basic data according to project initializes linear electric motors parameter, and and I_sm0、U_smAnd s_mTogether as input data；

B) motor stator electric current I is calculated_s；

If c) motor stator electric current I_s≥I_sm0, then I is taken_sm0Calculate as stator current；

D) motor thrust F is calculated_x；

E) train current acceleration a is calculated according to Newton's second law_x, speed v_xWith displacement s_x；

If f) present speed v_x＜ v_m, then update linear electric motors parameter according to current displacement and speed, return step a)；

If g) present speed v_x≥v_m, then accelerating sections displacement is exported

4. a kind of long stator synchronous linear motor driving Converter Capacity system of selection according to claim 3, it is special Levying and being, described basic data includes circuit line style data, station and electric substation's position data.