CN103778287A - PSCAD (Power System Computer Aided Design)-based mechanical complex torque coefficient scanning method - Google Patents

Abstract

The invention discloses a PSCAD (Power System Computer Aided Design)-based mechanical complex torque coefficient scanning method, and belongs to the field of stable control of power systems. The method comprises the following steps: (1) loading a mechanical complex torque coefficient scanning module onto electromagnetic transient software; (2) inputting a generator parameter and an axis coefficient, and establishing an axis motion equation; (3) inputting a scanning parameter; (4) bringing the scanning frequency into the axis motion equation, calculating a mechanical complex torque coefficient under the frequency, and separating the mechanical complex torque coefficient into a real part serving as a mechanical elastic coefficient and a virtual part serving as a mechanical damping coefficient; (5) judging whether the frequency surpasses a cut-off frequency or not, if the frequency does not surpasses the cut-off frequency, adding a scanning step length to the frequency, returning to the step 4), and calculating the mechanical complex torque coefficient of a next frequency point; if the frequency surpasses the cut-off frequency, stopping calculating and finishing scanning. By adopting the PSCAD-based mechanical complex torque coefficient scanning method, the mechanical complex torque coefficient of a generator to be researched and developed on a PSCAD platform can be scanned automatically, a high scanning speed and an accurate result are achieved, and research of the problem of subsynchronous oscillation is facilitated.

Description

The multiple moment coefficient scan method of a kind of machinery based on PSCAD

Technical field

The invention belongs to power system stability control field, particularly the multiple moment coefficient scan method of a kind of machinery based on PSCAD.

Background technology

Subsynchronous oscillation of electrical power system (Subsynchronous Oscillation, SSO) is a kind of serious stability problem, and the fatigue accumulation that it can cause genset macro-axis, even ruptures, and the safe operation of electric system in serious threat.Series capacitor compensation transmission line of electricity or DC transmission system all likely cause that thereby interaction bad between genset and electrical network causes sub-synchronous oscillation.The seventies in last century, in U.S. Square Butte high voltage direct current transmission project debug process, find first the SSO problem of the Turbo-generator Set being caused by HVDC.Afterwards, at CU, the IPP of the U.S., the Rihand-Deli of India, in the high voltage direct current transmission projects such as the Fenno-Skan of Sweden, had shown likely to cause SSO.

By to the end of the year 2012, the string benefit capacity having put into operation in the whole nation exceedes 30.688Gvar, and wherein controlled series compensation engineering has 3, and total volume is 849.8Mvar.To the year two thousand twenty, State Grid Corporation of China's 40 HVDC engineerings of having an appointment put into effect, wherein the electric power in the responsible relevant large electric power plant of DC engineering base is sent task outside greatly, these HVDC engineered capacities are large, electric pressure is high, transmission distance is far away, and because sending end is mainly large electric power plant unit overcritical, ultra supercritical, this SSO problem that DC control system is caused is more and more outstanding.Wherein, Ge Nan, day wide two times, Gao Ling and exhale the DC engineerings such as the Liao Dynasty once to find to exist HVDC to cause the risk of SSO.The SSO that therefore, analyse in depth, research may cause has become an important technical matters.

Multiple moment coefficient analytic approach is that I.M.Canay is first born in a kind of sub-synchronous oscillation analytical approach that nineteen eighty-two proposes.At present, for multiple moment coefficient, can obtain by system transter model inference, also can calculate by time-domain response curve, and then carry out according to stability criterion and multiple moment coefficient above the stability that analysis axis is.But the multiple moment coefficient calculated amount of being asked for by analytical method is huge, research is inconvenient, and owing to not yet setting up many FACTS device mathematical models within the scope of secondary frequencies, apply limited, and time-domain response curve can obtain by the test of physical system, also can carry out time domain by simulation software and calculate, wherein emulation mode speed is fast, cost is low, not affected by many FACTS device in system, obtained increasing application.

Summary of the invention

The problem existing for above-mentioned prior art, the present invention proposes the multiple moment coefficient scan method of a kind of machinery based on PSCAD, it is characterized in that, this scan method is specially:

1) on electro-magnetic transient software, load the multiple moment coefficient scan module of machinery;

2) input generator parameter and axle are parameter, and setting up axle is the equation of motion;

3) input scan parameter;

4) sweep frequency being brought into axle is the equation of motion, calculates the multiple moment coefficient of machinery under this frequency, and multiple machinery moment coefficient is pressed to real part imaginary part separately, and real part is mechanical elasticity coefficient, and imaginary part is mechanical damping coefficient;

5) judge whether this sweep frequency exceedes cutoff frequency, if do not exceed, on this frequency basis, add a scanning step, return to step 4), calculate the multiple moment coefficient of machinery of next Frequency point; If exceed, stop calculating, complete the scanning of the multiple moment coefficient of machinery.

The multiple moment coefficient scan module of machinery in described step 1) comprises parameter inputting interface, inputs generator parameter and axle is parameter for user.

Described step 2) in generator parameter comprise: steam turbine matter piece number, whether containing exciter, system power frequency, generator capacity, generator machinery synchronous rotational speed, axle is parameter system of units input parameter;

Axle is that parameter comprises: mass inertia time constant, elasticity coefficient between mass, mass self-damping, mutual damping between mass.

Described axle is that parameter system of units comprises 3 kinds: perunit value, international unit, English unit.

Described step 2) the center shafting equation of motion obtains by steam-electric generating set shafting model, and steam-electric generating set shafting model adopts simple lumped mass model, and the difference that is parameter system of units according to axle is carried out system of units conversion; Simple lumped mass block models definition: in this model, generator unit shaft system replaces with several rigid blocks, and by coupling together without quality spring.

Described step 2) the center shafting equation of motion is:

$\left\{\begin{array}{c}\frac{\mathrm{d\δ}}{\mathrm{dt}}=\mathrm{\ω}-{\mathrm{\ω}}_0\\ \frac{\mathrm{d\ω}}{\mathrm{dt}}=M^{-1}(T-\mathrm{K\δ}-\mathrm{D\ω})\end{array}\right.---\left(1\right)$

Wherein, ω=[ω ₁, ω ₂..., ω ₆] ^t, ω _ifor the electrical angle speed of mass i, unit is rad/s, i=1, and 2 ..., 6;

δ=[δ ₁, δ ₂..., δ ₆] ^t, δ _ifor the electrical angle displacement of mass i, unit is rad, and wherein mass 5 is corresponding to generator amature shaft part, δ ₅the angle of generator amature q axle with respect to reference voltage, i=1,2 ..., 6;

ω ₀=[ω ₀, ω ₀..., ω ₀] ^t, ω ₀for the angular velocity of generator amature under steady state (SS);

M=diag (M ₁, M ₂, M ₃, M ₄, M ₅, M ₆) for axle is the inertia time constant of each mass, unit is second, wherein:

i=1,2 ..., 6; J _ibe the mechanical rotation inertia of i mass, unit: kgm ²; ω _0mibe the specified mechanical angle speed of i mass, unit: rad/s; S _bfor power system capacity reference value, unit: VA;

T=[T ₁, T ₂, T ₃, T ₄, T ₅, T ₆] ^t, T _ifor the torque on mass i, wherein T ₅=-T _e, T _efor the electrical torque of generator, i=1,2 ..., 6;

$D=\left[\begin{array}{cccccc}{D}_{11}+D_{12}& -D_{12}& & & & \\ -D_{12}& D_{12}+D_{22}+D_{12}& -D_{23}& & & \\ & -D_{23}& D_{23}+D_{33}+D_{34}& -D_{34}& & \\ & & -D_{34}& D_{34}+D_{44}+D_{45}& -D_{45}& \\ & & & -D_{45}& D_{45}+D_{55}+D_{56}& -D_{56}\\ & & & & -D_{56}& D_{56}+D_{66}\end{array}\right]$ For the damping matrix of axle system, wherein D _iifor axle is the self-damping coefficient of each mass, D _{i, i+1}for the mutual damping coefficient between adjacent mass i and i+1, i=1,2 ..., 6;

$K=\left[\begin{array}{cccccc}{K}_{12}& -K_{12}& & & & \\ -K_{12}& K_{12}+K_{23}& -K_{23}& & & \\ & -K_{23}& K_{23}+K_{34}& -K_{34}& & \\ & & -K_{34}& K_{34}+K_{45}& -K_{45}& \\ & & & -K_{45}& K_{45}+K_{56}& -K_{56}\\ & & & & -K_{56}& K_{56}\end{array}\right],$ Wherein K _{i, i+1}for the elasticity coefficient between adjacent mass i and i+1.

In described step 3), sweep parameter comprises: initial frequency, cutoff frequency, scanning step.

In described step 4), the computing formula of the multiple moment coefficient of machinery is:

On exciter, produce armature reaction torque Δ T ignoring ₆, also neglect steam turbine and speed regulator effect Δ T simultaneously ₁to Δ T ₄situation under, retain Δ δ ₅=Δ δ and Δ T ₅=-Δ T _etwo state variables, its dependent variable of cancellation, can obtain following relational expression

K _M(p)Δδ=-ΔT _e （2）

Wherein, K _m(p) be differentiating operator

rational fraction, be Δ T _eand the transport function between Δ δ;

Formula (2) is derived, cancellation Δ ω in the equation of motion (1) of synchronous generator mechanical axis system _i, obtain formula (3)

$\left[\begin{array}{cccccc}{M}_1\left(p\right)& -K_1\left(p\right)& & & & \\ -K_1\left(p\right)& M_2\left(p\right)& -K_2\left(p\right)& & & \\ & -K_2\left(p\right)& M_3\left(p\right)& -K_3\left(p\right)& & \\ & & {-K}_3\left(p\right)& M_4\left(p\right)& -K_4\left(p\right)& \\ & & & -K_4\left(p\right)& M_5\left(p\right)& -K_5\left(p\right)\\ & & & & -K_5\left(p\right)& M_6\left(p\right)\end{array}\right]\×\left[\begin{array}{c}\mathrm{\Δ}{\mathrm{\δ}}_1\\ \mathrm{\Δ}{{\mathrm{\δ}}_2}_{}\\ \mathrm{\Δ}{{\mathrm{\δ}}_3}_{}\\ \mathrm{\Δ}{{\mathrm{\δ}}_4}_{}\\ \mathrm{\Δ}{{\mathrm{\δ}}_{}}_5\\ \mathrm{\Δ}{{\mathrm{\δ}}_{}}_6\end{array}\right]=\left[\begin{array}{c}0\\ 0\\ 0\\ 0\\ -\mathrm{\Δ}{T}_e\\ 0\end{array}\right]---\left(3\right)$

Wherein,

M _i(p)=T _Jip ²+(D _i+D _(i-1),i+D _i,(i+1))p+K _(i-1),i+K _i,(i+1),i=1,2,...,6，

K _i(p)=D _i,(i+1)p+K _i,(i+1),i=1,2,...,5，K _0,1=K _6,7=0,D _0,1=D _6,7=0

Cancellation Δ δ in formula (3) ₁to Δ δ ₄with Δ δ ₆,

[M ₅(p)-K ₄(p)A ₅(p)-K ₅ ²(p)/M ₆(p)]Δδ=-ΔTe （4）

Wherein, A ₅(p) make A ₁(p)=0 is in the situation of initial value, calculates with following recursion formula

$A_i\left(p\right)=\frac{K_{i-1}\left(p\right)}{M_{i-1}\left(p\right)-K_{i-2}\left(p\right)A_{i-1}\left(p\right)}---\left(5\right)$

Formula (4) and (2) are compared, obtain K _m(p):

K _M(p)=[M ₅(p)-K ₄(p)A ₅(p)-K ₅ ²(p)/M ₆(p)] （6）

It is the function of frequency, makes p=j ζ, and presses real part imaginary part and launch

K _M(jζ)　=　K _m(ζ)　　+　jζD _m(ζ) （7）

Wherein, K _m(ζ) be mechanical part elasticity coefficient, D _m(ζ) be mechanical part ratio of damping, they are all functions of frequency.

The beneficial effect of the invention: the method that the present invention proposes can realize to be treated the multiple moment coefficient of research and development electromechanics and realize autoscan on PSCAD platform, and scanning is fast, and result is accurate, is conducive to the research of researchist to sub-synchronous oscillation problem.

Accompanying drawing explanation

Fig. 1 shows the multiple moment coefficient scanning process block diagram of one machinery that the present invention proposes;

Fig. 2 shows generator machinery elasticity coefficient curve in the first master pattern;

Fig. 3 shows generator machinery ratio of damping curve in the first master pattern.

Embodiment

Below in conjunction with drawings and Examples, method proposed by the invention is described further.

Be illustrated in figure 1 the multiple moment coefficient scanning process figure of machinery that the present invention proposes, the concrete steps of this scan method are:

1) on electro-magnetic transient software, load the multiple moment coefficient scan module of machinery;

The multiple moment coefficient scan module of this machinery comprises parameter inputting interface, inputs generator parameter and axle is parameter for user.

2) input generator parameter and axle are parameter, and setting up axle according to these parameters is the equation of motion;

Generator parameter: steam turbine matter piece number (Number of turbines), whether containing exciter (Model Exciter Mass), system power frequency (Electrical base frequency), generator capacity (Machine total MVA), generator machinery synchronous rotational speed (Machine mechanical synchronous speed), axle is parameter system of units (Unit).Axle is that parameter system of units (Unit) can be: perunit value (per unit), international unit (International system of units), English unit (Imperial units).

Axle is parameter: mass inertia time constant (Inertia Time Constant), elasticity coefficient between mass (Shaft Spring Constant), mass self-damping (Self Damping), mutual damping between mass (Mutul Damping).

Axle is that the equation of motion is obtained by steam-electric generating set shafting model, and steam-electric generating set shafting model adopts simple lumped mass model, and the difference that is parameter system of units according to axle is carried out system of units conversion; Simple lumped mass block models definition: in this model, generator unit shaft system replaces with several rigid blocks, and by coupling together without quality spring.

Axle is that the equation of motion is:

$\left\{\begin{array}{c}\frac{\mathrm{d\δ}}{\mathrm{dt}}=\mathrm{\ω}-{\mathrm{\ω}}_0\\ \frac{\mathrm{d\ω}}{\mathrm{dt}}=M^{-1}(T-\mathrm{K\δ}-\mathrm{D\ω})\end{array}\right.---\left(1\right)$

Wherein, ω=[ω ₁, ω ₂..., ω ₆] ^t, ω _ifor the electrical angle speed of mass i, unit is rad/s, i=1, and 2 ..., 6;

δ=[δ ₁, δ ₂..., δ ₆] ^t, δ _ifor the electrical angle displacement of mass i, unit is rad, and wherein mass 5 is corresponding to generator amature shaft part, δ ₅the angle of generator amature q axle with respect to reference voltage, i=1,2 ..., 6;

ω ₀=[ω ₀, ω ₀..., ω ₀] ^t, ω ₀for the angular velocity of generator amature under steady state (SS);

M=diag (M ₁, M ₂, M ₃, M ₄, M ₅, M ₆) for axle is the inertia time constant of each mass, unit is second, wherein:

i=1,2 ..., 6; J _ibe the mechanical rotation inertia of i mass, unit: kgm ²; ω _0mibe the specified mechanical angle speed of i mass, unit: rad/s; S _bfor power system capacity reference value, unit: VA;

T=[T ₁, T ₂, T ₃, T ₄, T ₅, T ₆] ^t, T _ifor the torque on mass i, wherein T ₅=-T _e, T _efor the electrical torque of generator, i=1,2 ..., 6;

$D=\left[\begin{array}{cccccc}{D}_{11}+D_{12}& -D_{12}& & & & \\ -D_{12}& D_{12}+D_{22}+D_{12}& -D_{23}& & & \\ & -D_{23}& D_{23}+D_{33}+D_{34}& -D_{34}& & \\ & & -D_{34}& D_{34}+D_{44}+D_{45}& -D_{45}& \\ & & & -D_{45}& D_{45}+D_{55}+D_{56}& -D_{56}\\ & & & & -D_{56}& D_{56}+D_{66}\end{array}\right]$ For the damping matrix of axle system, wherein D _iifor axle is the self-damping coefficient of each mass, D _{i, i+1}for the mutual damping coefficient between adjacent mass i and i+1, i=1,2 ..., 6;

$K=\left[\begin{array}{cccccc}{K}_{12}& -K_{12}& & & & \\ -K_{12}& K_{12}+K_{23}& -K_{23}& & & \\ & -K_{23}& K_{23}+K_{34}& -K_{34}& & \\ & & -K_{34}& K_{34}+K_{45}& -K_{45}& \\ & & & -K_{45}& K_{45}+K_{56}& -K_{56}\\ & & & & -K_{56}& K_{56}\end{array}\right],$ Wherein K _{i, i+1}for the elasticity coefficient between adjacent mass i and i+1.

3) input scan parameter;

Sweep parameter comprises: initial frequency, cutoff frequency, scanning step.Scanning step, also referred to as scanning accuracy, can be as accurate as 0.01Hz.

4) sweep frequency being brought into axle is the equation of motion, calculates the multiple moment coefficient of machinery under this frequency, and multiple machinery moment coefficient is pressed to real part imaginary part separately, and real part is mechanical elasticity coefficient, and imaginary part is mechanical damping coefficient;

The computing formula of the multiple moment coefficient of machinery is:

On exciter, produce armature reaction torque Δ T ignoring ₆, also neglect steam turbine and speed regulator effect Δ T simultaneously ₁to Δ T ₄situation under, retain Δ δ ₅=Δ δ and Δ T ₅=-Δ T _etwo state variables, its dependent variable of cancellation, can obtain following relational expression

K _M(p)Δδ=-ΔT _e （2）

Wherein, K _m(p) be differentiating operator

rational fraction, be Δ T _eand the transport function between Δ δ;

Formula (2) is derived, cancellation Δ ω in the equation of motion (1) of synchronous generator mechanical axis system _i, obtain formula (3)

$\left[\begin{array}{cccccc}{M}_1\left(p\right)& -K_1\left(p\right)& & & & \\ -K_1\left(p\right)& M_2\left(p\right)& -K_2\left(p\right)& & & \\ & -K_2\left(p\right)& M_3\left(p\right)& -K_3\left(p\right)& & \\ & & {-K}_3\left(p\right)& M_4\left(p\right)& -K_4\left(p\right)& \\ & & & -K_4\left(p\right)& M_5\left(p\right)& -K_5\left(p\right)\\ & & & & -K_5\left(p\right)& M_6\left(p\right)\end{array}\right]\×\left[\begin{array}{c}\mathrm{\Δ}{\mathrm{\δ}}_1\\ \mathrm{\Δ}{{\mathrm{\δ}}_2}_{}\\ \mathrm{\Δ}{{\mathrm{\δ}}_3}_{}\\ \mathrm{\Δ}{{\mathrm{\δ}}_4}_{}\\ \mathrm{\Δ}{{\mathrm{\δ}}_{}}_5\\ \mathrm{\Δ}{{\mathrm{\δ}}_{}}_6\end{array}\right]=\left[\begin{array}{c}0\\ 0\\ 0\\ 0\\ -\mathrm{\Δ}{T}_e\\ 0\end{array}\right]---\left(3\right)$

Wherein,

M _i(p)=T _Jip ²+(D _i+D _(i-1),i+D _i,(i+1))p+K _(i-1),i+K _i,(i+1),i=1,2,...,6，

K _i(p)=D _i,(i+1)p+K _i,(i+1),i=1,2,...,5，K _0,1=K _6,7=0,D _0,1=D _6,7=0

Cancellation Δ δ in formula (3) ₁to Δ δ ₄with Δ δ ₆,

[M ₅(p)-K ₄(p)A ₅(p)-K ₅ ²(p)/M ₆(p)]Δδ=-ΔTe （4）

Wherein, A ₅(p) make A ₁(p)=0 is in the situation of initial value, calculates with following recursion formula

$A_i\left(p\right)=\frac{K_{i-1}\left(p\right)}{M_{i-1}\left(p\right)-K_{i-2}\left(p\right)A_{i-1}\left(p\right)}---\left(5\right)$

Formula (4) and (2) are compared, obtain K _m(p):

K _M(p)=[M ₅(p)-K ₄(p)A ₅(p)-K ₅ ²(p)/M ₆(p)] （6）

It is the function of frequency, makes p=j ζ, and presses real part imaginary part and launch

K _M(jζ)　=　K _m(ζ)　　+　jζD _m(ζ) （7）

Wherein, K _m(ζ) be mechanical part elasticity coefficient, D _m(ζ) be mechanical part ratio of damping, they are all functions of frequency.

5) judge whether this sweep frequency exceedes cutoff frequency, if do not exceed, on this frequency basis, add a scanning step, return to step 4), calculate the multiple moment coefficient of machinery of next Frequency point; If exceed, stop calculating, complete the scanning of the multiple moment coefficient of machinery.

The present invention adopts the method for operation in many ways, successively calculates the mechanical elasticity COEFFICIENT K under each Frequency point according to analytical algorithm _m, mechanical damping coefficient D _m.

Be generator machinery elasticity coefficient curve and mechanical damping coefficient curve map in the first master pattern as shown in Figures 2 and 3; The multiple torque elasticity coefficient K of machinery _m(ζ) represent in the multiple torque increment of equivalent mechanical and rotor angle proportionate fraction, K _mthe natural torsion frequency that=0 each point corresponding to axle is, near natural torsion frequency, K _mvariation very fast, be almost a vertical straight line; The multiple torque ratio of damping D of machinery _m(ζ) represent in equivalent mechanical torque increment and rotor velocity proportionate fraction, in whole frequency range, axle is mechanical damping coefficient D _m(ζ) be always positive, illustrate that axle system itself is stable.

The above; only for preferably embodiment of the present invention, but protection scope of the present invention is not limited to this, is anyly familiar with in technical scope that those skilled in the art disclose in the present invention; the variation that can expect easily or replacement, within all should being encompassed in protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claim.

Claims (8)

1. the multiple moment coefficient scan method of the machinery based on PSCAD, is characterized in that, this scan method is specially:

1) on electro-magnetic transient software, load the multiple moment coefficient scan module of machinery;

2) input generator parameter and axle are parameter, and setting up axle is the equation of motion;

3) input scan parameter;

4) sweep frequency being brought into axle is the equation of motion, calculates the multiple moment coefficient of machinery under this frequency, and multiple machinery moment coefficient is pressed to real part imaginary part separately, and real part is mechanical elasticity coefficient, and imaginary part is mechanical damping coefficient;

5) judge whether this sweep frequency exceedes cutoff frequency, if do not exceed, on this frequency basis, add a scanning step, return to step 4), calculate the multiple moment coefficient of machinery of next Frequency point; If exceed, stop calculating, complete the scanning of the multiple moment coefficient of machinery.

2. the multiple moment coefficient scan method of a kind of machinery based on PSCAD according to claim 1, is characterized in that, the multiple moment coefficient scan module of machinery in described step 1) comprises parameter inputting interface, inputs generator parameter and axle is parameter for user.

3. the multiple moment coefficient scan method of a kind of machinery based on PSCAD according to claim 1, it is characterized in that, described step 2) in generator parameter comprise: steam turbine matter piece number, whether contain exciter, system power frequency, generator capacity, generator machinery synchronous rotational speed, axle is parameter system of units input parameter;

Axle is that parameter comprises: mass inertia time constant, elasticity coefficient between mass, mass self-damping, mutual damping between mass.

4. the multiple moment coefficient scan method of a kind of machinery based on PSCAD according to claim 3, is characterized in that, described axle is that parameter system of units comprises 3 kinds: perunit value, international unit, English unit.

5. the multiple moment coefficient scan method of a kind of machinery based on PSCAD according to claim 1, it is characterized in that, described step 2) the center shafting equation of motion obtains by steam-electric generating set shafting model, steam-electric generating set shafting model adopts simple lumped mass model, and the difference that is parameter system of units according to axle is carried out system of units conversion; Simple lumped mass block models definition: in this model, generator unit shaft system replaces with several rigid blocks, and by coupling together without quality spring.

6. the multiple moment coefficient scan method of a kind of machinery based on PSCAD according to claim 1 or 5, is characterized in that described step 2) the center shafting equation of motion is:

$\left\{\begin{array}{c}\frac{\mathrm{d\δ}}{\mathrm{dt}}=\mathrm{\ω}-{\mathrm{\ω}}_0\\ \frac{\mathrm{d\ω}}{\mathrm{dt}}=M^{-1}(T-\mathrm{K\δ}-\mathrm{D\ω})\end{array}\right.---\left(1\right)$

Wherein, ω=[ω ₁, ω ₂..., ω ₆] ^t, ω _ifor the electrical angle speed of mass i, unit is rad/s, i=1, and 2 ..., 6;

δ=[δ ₁, δ ₂..., δ ₆] ^t, δ _ifor the electrical angle displacement of mass i, unit is rad, and wherein mass 5 is corresponding to generator amature shaft part, δ ₅the angle of generator amature q axle with respect to reference voltage, i=1,2 ..., 6;

ω ₀=[ω ₀, ω ₀..., ω ₀] ^t, ω ₀for the angular velocity of generator amature under steady state (SS);

M=diag (M ₁, M ₂, M ₃, M ₄, M ₅, M ₆) for axle is the inertia time constant of each mass, unit is second, wherein:

i=1,2 ..., 6; J _ibe the mechanical rotation inertia of i mass, unit: kgm ²; ω _0mibe the specified mechanical angle speed of i mass, unit: rad/s; S _bfor power system capacity reference value, unit: VA;

T=[T ₁, T ₂, T ₃, T ₄, T ₅, T ₆] ^t, T _ifor the torque on mass i, wherein T ₅=-T _e, T _efor the electrical torque of generator, i=1,2 ..., 6;

$D=\left[\begin{array}{cccccc}{D}_{11}+D_{12}& -D_{12}& & & & \\ -D_{12}& D_{12}+D_{22}+D_{12}& -D_{23}& & & \\ & -D_{23}& D_{23}+D_{33}+D_{34}& -D_{34}& & \\ & & -D_{34}& D_{34}+D_{44}+D_{45}& -D_{45}& \\ & & & -D_{45}& D_{45}+D_{55}+D_{56}& -D_{56}\\ & & & & -D_{56}& D_{56}+D_{66}\end{array}\right]$ For the damping matrix of axle system, wherein D _iifor axle is the self-damping coefficient of each mass, D _{i, i+1}for the mutual damping coefficient between adjacent mass i and i+1, i=1,2 ..., 6;

$K=\left[\begin{array}{cccccc}{K}_{12}& -K_{12}& & & & \\ -K_{12}& K_{12}+K_{23}& -K_{23}& & & \\ & -K_{23}& K_{23}+K_{34}& -K_{34}& & \\ & & -K_{34}& K_{34}+K_{45}& -K_{45}& \\ & & & -K_{45}& K_{45}+K_{56}& -K_{56}\\ & & & & -K_{56}& K_{56}\end{array}\right],$ Wherein K _{i, i+1}for the elasticity coefficient between adjacent mass i and i+1.

7. the multiple moment coefficient scan method of a kind of machinery based on PSCAD according to claim 1, is characterized in that, in described step 3), sweep parameter comprises: initial frequency, cutoff frequency, scanning step.

8. the multiple moment coefficient scan method of a kind of machinery based on PSCAD according to claim 1, is characterized in that, in described step 4), the computing formula of the multiple moment coefficient of machinery is:

On exciter, produce armature reaction torque Δ T ignoring ₆, also neglect steam turbine and speed regulator effect Δ T simultaneously ₁to Δ T ₄situation under, retain Δ δ ₅=Δ δ and Δ T ₅=-Δ T _etwo state variables, its dependent variable of cancellation, can obtain following relational expression

K _M(p)Δδ=-ΔT _e （2）

Wherein, K _m(p) be differentiating operator

rational fraction, be Δ T _eand the transport function between Δ δ;

Formula (2) is derived, cancellation Δ ω in the equation of motion (1) of synchronous generator mechanical axis system _i, obtain formula (3)

$\left[\begin{array}{cccccc}{M}_1\left(p\right)& -K_1\left(p\right)& & & & \\ -K_1\left(p\right)& M_2\left(p\right)& -K_2\left(p\right)& & & \\ & -K_2\left(p\right)& M_3\left(p\right)& -K_3\left(p\right)& & \\ & & {-K}_3\left(p\right)& M_4\left(p\right)& -K_4\left(p\right)& \\ & & & -K_4\left(p\right)& M_5\left(p\right)& -K_5\left(p\right)\\ & & & & -K_5\left(p\right)& M_6\left(p\right)\end{array}\right]\×\left[\begin{array}{c}\mathrm{\Δ}{\mathrm{\δ}}_1\\ \mathrm{\Δ}{{\mathrm{\δ}}_2}_{}\\ \mathrm{\Δ}{{\mathrm{\δ}}_3}_{}\\ \mathrm{\Δ}{{\mathrm{\δ}}_4}_{}\\ \mathrm{\Δ}{{\mathrm{\δ}}_{}}_5\\ \mathrm{\Δ}{{\mathrm{\δ}}_{}}_6\end{array}\right]=\left[\begin{array}{c}0\\ 0\\ 0\\ 0\\ -\mathrm{\Δ}{T}_e\\ 0\end{array}\right]---\left(3\right)$

Wherein,

M _i(p)=T _Jip ²+(D _i+D _(i-1),i+D _i,(i+1))p+K _(i-1),i+K _i,(i+1),i=1,2,...,6，

K _i(p)=D _i,(i+1)p+K _i,(i+1),i=1,2,...,5，K _0,1=K _6,7=0,D _0,1=D _6,7=0

Cancellation Δ δ in formula (3) ₁to Δ δ ₄with Δ δ ₆,

[M ₅(p)-K ₄(p)A ₅(p)-K ₅ ²(p)/M ₆(p)]Δδ=-ΔTe （4）

Wherein, A ₅(p) make A ₁(p)=0 is in the situation of initial value, calculates with following recursion formula

$A_i\left(p\right)=\frac{K_{i-1}\left(p\right)}{M_{i-1}\left(p\right)-K_{i-2}\left(p\right)A_{i-1}\left(p\right)}---\left(5\right)$

Formula (4) and (2) are compared, obtain K _m(p):

K _M(p)=[M ₅(p)-K ₄(p)A ₅(p)-K ₅ ²(p)/M ₆(p)] （6）

It is the function of frequency, makes p=j ζ, and presses real part imaginary part and launch

K _M(jζ)　=　K _m(ζ)　　+　jζD _m(ζ) （7）

Wherein, K _m(ζ) be mechanical part elasticity coefficient, D _m(ζ) be mechanical part ratio of damping, they are all functions of frequency.

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