Synchronous Machine Salient Pole (standard)

Salient-pole synchronous machine with standard parameterization

Library

Machines / Synchronous Machine (Salient Pole)

Description

The Synchronous Machine Salient Pole (standard) block models a salient-pole synchronous machine with parameterization using standard parameters.

Electrical Defining Equations

The synchronous machine equations are expressed with respect to a rotating reference frame defined by the equation

θe(t)=N*θr(t),

where:

  • θe is the electrical angle.

  • N is the number of pole pairs.

  • θr is the rotor angle.

Park's transformation maps the synchronous machine equations to the rotating reference frame with respect to the electrical angle. Park's transformation is defined by

Ps=23[cosθecos(θe2π3)cos(θe+2π3)sinθesin(θe2π3)sin(θe2π3)121212].

Park's transformation is used to define the per-unit synchronous machine equations. The stator voltage equations are defined by

ed=1ωbasedψddtΨqωrRaid,

eq=1ωbasedψqdt+ΨdωrRaiq,

and

e0=1ωbasedΨ0dtRai0,

where:

  • ed, eq, and e0 are the d-axis, q-axis, and zero-sequence stator voltages, defined by

    [edeqe0]=Ps[vavbvc],

    where va, vb, and vc are the stator voltages measured from port ~ to neutral port n.

  • ωbase is the per-unit base electrical speed.

  • ψd, ψq, and ψ0 are the d-axis, q-axis, and zero-sequence stator flux linkages.

  • ωr is the per-unit rotor rotational speed.

  • Ra is the stator resistance.

  • id, iq and i0 are the d-axis, q-axis, and zero-sequence stator currents, defined by

    [idiqi0]=Ps[iaibic],

    where ia, ib, and ic are the stator currents flowing from port ~ to port n.

The rotor voltage equations are defined by

efd=1ωbasedΨfddt+Rfdifd,

e1d=1ωbasedΨ1ddt+R1di1d=0,

and

e1q=1ωbasedΨ1qdt+R1qi1q=0,

where:

  • efd is the field voltage.

  • e1d, and e1q are the voltages across the d-axis damper winding 1 and q-axis damper winding 1. They are equal to 0.

  • ψfd, ψ1d, and ψ1q, are the magnetic fluxes linking the field circuit, d-axis damper winding 1, and q-axis damper winding 1.

  • Rfd, R1d, and R1q are the resistances of rotor field circuit, d-axis damper winding 1, and q-axis damper winding 1.

  • ifd, i1d, and i1q are the currents flowing in the field circuit, d-axis damper winding 1, and q-axis damper winding 1.

The saturation equations are defined by

ψat=ψd2+ψq2,

Ks=1 (If saturation is disabled),

Ks=f(ψat) (If saturation is enabled),

and

Lad=Ks*Ladu,

where:

  • ψat is the air-gap flux linkage.

  • Ks is the saturation factor.

  • Ladu is the unsaturated mutual inductance of the stator d-axis.

  • Lad is the mutual inductance of the stator d-axis.

The saturation factor function, f, is calculated from the per-unit open-circuit lookup table as:

Lad=dψatdifd,

Vag=g(ifd),

and

Lad=dg(ifd)difd=dVagdifd,

where:

  • Vag is the per-unit air-gap voltage.

In per-unit,

Ks=LadLadu,

and

ψat=Vag

can be rearranged to

Ks=f(ψat).

The stator flux linkage equations are defined by

Ψd=(Lad+Li)id+Ladifd+Ladi1d,

Ψq=(Laq+Li)iq+Laqi1q,

and

Ψ0=L0i0,

where:

  • Ll is the stator leakage inductance.

  • Lad and Laq are the mutual inductances of the stator d-axis and q-axis.

The rotor flux linkage equations are defined by

ψfd=Lffdifd+Lf1di1dLadid,

ψ1d=Lf1difd+L11di1dLadid,

and

ψ1q=L11qi1qLaqiq,

where:

  • Lffd, L11d, and L11q are the self-inductances of the rotor field circuit, d-axis damper winding 1, and q-axis damper winding 1. Lf1d is the rotor field circuit and d-axis damper winding 1 mutual inductance. They are defined by the following equations.

    Lffd=Lad+Lfd

    Lf1d=LffdLfd

    L11d=Lf1d+L1d

    L11q=Laq+L1q

These equations assume that per-unit mutual inductance L12q = Laq, i.e., the stator and rotor currents in the q-axis all link a single mutual flux represented by Laq.

The rotor torque is defined by

Te=ΨdiqΨqid.

These defining equations do not describe the time constants you can set in the dialog box. To see their relationship with the equation coefficients, see [1].

Display Options

For synchronous machine blocks, you can perform display actions using the Power Systems menu on the block context menu.

Right-click the block. From the context menu, select one of the following from the Power Systems > Synchronous Machine menu:

  • Display Base Values displays the machine per-unit base values at the MATLAB® command prompt.

  • Display Associated Base Values displays associated per-unit base values at the MATLAB command prompt.

  • Associated Initial Conditions displays associated initial conditions at the MATLAB command prompt.

  • Plot Open-Circuit Saturation (pu) plots air-gap voltage, Vag, versus field current, ifd, (both measured in per-unit) in a MATLAB figure window. The plot contains three traces:

    • Unsaturated: Stator d-axis mutual inductance (unsaturated), Ladu you specify

    • Saturated: Per-unit open-circuit lookup table (Vag versus ifd) you specify

    • Derived: Open-circuit lookup table (per-unit) derived from the Per-unit open-circuit lookup table (Vag versus ifd) you specify. This data is used to calculate the saturation factor, Ks, versus magnetic flux linkage, ψat, characteristic.

  • Plot Saturation Factor (pu) plots saturation factor, Ks, versus magnetic flux linkage, ψat, (both measured in per-unit) in a MATLAB figure window using the present machine parameters. This is derived from parameters you specify:

    • Stator d-axis mutual inductance (unsaturated), Ladu

    • Per-unit field current saturation data, ifd

    • Per-unit air-gap voltage saturation data, Vag

Dialog Box and Parameters

Main Tab

Rated apparent power

Rated apparent power. The default value is 300e6 VA.

Rated voltage

RMS rated line-line voltage. The default value is 24e3 V.

Rated electrical frequency

Nominal electrical frequency at which rated apparent power is quoted. The default value is 60 Hz.

Number of pole pairs

Number of machine pole pairs. The default value is 10.

Specify field circuit input required to produce rated terminal voltage at no load by

Choose between Field circuit voltage and Field circuit current. The default value is Field circuit current.

Field circuit current

This parameter is visible only when Specify field circuit input required to produce rated terminal voltage at no load by is set to Field circuit current. The default value is 1000 A.

Field circuit voltage

This parameter is visible only when Specify field circuit input required to produce rated terminal voltage at no load by is set to Field circuit voltage. The default value is 216.54 V.

Impedances Tab

Stator resistance, Ra

Stator resistance. The default value is 0.011 pu.

Stator leakage reactance, Xl

Stator leakage reactance. The default value is 0.15 pu.

d-axis synchronous reactance, Xd

The d-axis synchronous reactance. The default value is 1.05 pu.

q-axis synchronous reactance, Xq

The q-axis synchronous reactance. The default value is 0.7 pu.

zero-sequence reactance, X0

The zero-sequence reactance. The default value is 0 pu.

d-axis transient reactance, Xd'

The d-axis transient reactance. The default value is 0.35 pu.

d-axis subtransient reactance, Xd''

The d-axis subtransient reactance. The default value is 0.25 pu.

q-axis subtransient reactance, Xq''

The q-axis subtransient reactance. The default value is 0.325 pu.

Time Constants Tab

Specify d-axis transient time constant

Select between Open circuit value and Short circuit value. The default value is Open circuit value.

d-axis transient open circuit, Td0'

The d-axis transient open circuit time constant. This parameter is visible only when Specify d-axis transient time constant is set to Open circuit value. The default value is 5.25 s.

d-axis transient short circuit, Td'

The d-axis transient short circuit time constant. This parameter is visible only when Specify d-axis transient time constant is set to Short circuit value. The default value is 1.75 s.

Specify d-axis subtransient time constant

Select between Open circuit value and Short circuit value. The default value is Open circuit value.

d-axis subtransient open circuit, Td0''

The d-axis subtransient open circuit time constant. This parameter is visible only when Specify d-axis subtransient time constant is set to Open circuit value. The default value is 0.03 s.

d-axis subtransient short circuit, Td''

The d-axis subtransient short circuit time constant. This parameter is visible only when Specify d-axis subtransient time constant is set to Short circuit value. The default value is 0.0214 s.

Specify q-axis subtransient time constant

Select between Open circuit value and Short circuit value. The default value is Open circuit value.

q-axis subtransient open circuit, Tq0''

The q-axis subtransient open circuit time constant. This parameter is visible only when Specify q-axis subtransient time constant is set to Open circuit value. The default value is 0.05 s.

q-axis subtransient short circuit, Tq''

The q-axis subtransient short circuit time constant. This parameter is visible only when Specify q-axis subtransient time constant is set to Short circuit value. The default value is 0.0232 s.

Saturation Tab

Magnetic saturation representation

Block magnetic saturation representation. Options are:

  • None

  • Per-unit open-circuit lookup table (Vag versus ifd)

The default value is None.

Per-unit field current saturation data, ifd

The field current, ifd, data populates the air-gap voltage, Vag, versus field current, ifd, lookup table. This parameter is only visible when you set Magnetic saturation representation to Per-unit open-circuit lookup table (Vag versus ifd). This parameter must contain a vector with at least five elements. The default value is [0.00, 0.48, 0.76, 1.38, 1.79] pu.

Per-unit air-gap voltage saturation data, Vag

The air-gap voltage, Vag, data populates the air-gap voltage, Vag, versus field current, ifd, lookup table. This parameter is only visible when you set Magnetic saturation representation to Per-unit open-circuit lookup table (Vag versus ifd). This parameter must contain a vector with at least five elements. The default value is [0.00 0.43 0.59 0.71 0.76] pu.

Initial Conditions Tab

Specify initialization by

Options include:

  • Electrical power and voltage output

  • Mechanical and magnetic states

The default value is Electrical power and voltage output.

Terminal voltage magnitude

Initial RMS line-line voltage. This parameter is visible only when you set Specify initialization by to Electrical power and voltage output. The default value is 24e3 V.

Terminal voltage angle

Initial voltage angle. This parameter is visible only when you set Specify initialization by to Electrical power and voltage output. The default value is 0 deg.

Terminal active power

Initial active power. This parameter is visible only when Specify initialization by is set to Electrical power and voltage output. The default value is 270e6 VA.

Terminal reactive power

Initial reactive power. This parameter is visible only when you set Specify initialization by to Electrical power and voltage output. The default value is 0 VA.

Initial rotor angle

Initial rotor angle. During steady-state operation, set this parameter to the sum of the load angle and required terminal voltage offset. This parameter is visible only when you set Specify initialization by to Mechanical and magnetic states. The default value is 0 deg.

Initial stator d-axis magnetic flux linkage

Stator d-axis initial flux linkage. This parameter is visible only when you set Specify initialization by to Mechanical and magnetic states. The default value is 0 pu.

Initial stator q-axis magnetic flux linkage

Stator q-axis initial flux linkage. This parameter is visible only when you set Specify initialization by to Mechanical and magnetic states. The default value is 0 pu.

Initial stator zero-sequence magnetic flux linkage

Zero-sequence initial flux linkage. This parameter is visible only when you set Specify initialization by to Mechanical and magnetic states. The default value is 0 pu.

Initial field circuit magnetic flux linkage

Field circuit initial flux linkage. This parameter is visible only when you set Specify initialization by to Mechanical and magnetic states. The default value is 0 pu.

Initial d-axis damper winding 1 magnetic flux linkage

d-axis damper winding 1 initial flux linkage. This parameter is visible only when you set Specify initialization by to Mechanical and magnetic states. The default value is 0 pu.

Initial q-axis damper winding 1 magnetic flux linkage

The q-axis damper winding 1 initial flux linkage. This parameter is visible only when you set Specify initialization by to Mechanical and magnetic states. The default value is 0 pu.

Initial q-axis damper winding 2 magnetic flux linkage

The q-axis damper winding 2 initial flux linkage. This parameter is visible only when you set Specify initialization by to Mechanical and magnetic states. The default value is 0 pu.

Ports

The block has the following ports:

fd+

Electrical conserving port corresponding to the field winding positive terminal

fd-

Electrical conserving port corresponding to the field winding negative terminal

R

Mechanical rotational conserving port associated with the machine rotor

C

Mechanical rotational conserving port associated with the machine case

pu

Physical signal vector port associated with the machine per-unit measurements. The vector elements are:

  • pu_fd_Efd

  • pu_fd_Ifd

  • pu_torque

  • pu_velocity

  • pu_ed

  • pu_ed

  • pu_e0

  • pu_id

  • pu_iq

  • pu_i0

~

Expandable three-phase port associated with the stator windings

n

Electrical conserving port associated with the neutral point of the wye winding configuration

References

[1] Kundur, P. Power System Stability and Control. New York, NY: McGraw Hill, 1993.

[2] Lyshevski, S. E. Electromechanical Systems, Electric Machines and Applied Mechatronics. Boca Raton, FL: CRC Press, 1999.

Was this topic helpful?