Switched Shunt Model: SVSMO1

Some important SVC Control Considerations when running Transient Stability.

Following checks and corrections are applied during Validation and AutoCorrection.

  • If 0.0 < Tb1 < 0.5*Mult*TimeStep then Tb1 = 0, ElseIf 0.5*Mult*TimeStep < Tb1 < Mult*TimeStep then Tb1 = Mult*TimeStep
  • If 0.0 < Tb2 < 0.5*Mult*TimeStep then Tb2 = 0, ElseIf 0.5*Mult*TimeStep < Tb2 < Mult*TimeStep then Tb2 = Mult*TimeStep
  • If 0.0 < Tdelay1 < 0.5*Mult*TimeStep then Tdelay1 = 0, ElseIf 0.5*Mult*TimeStep < Tdelay1 < Mult*TimeStep then Tdelay1 = Mult*TimeStep
  • If 0.0 < Tdelay2 < 0.5*Mult*TimeStep then Tdelay2 = 0, ElseIf 0.5*Mult*TimeStep < Tdelay2 < Mult*TimeStep then Tdelay2 = Mult*TimeStep
  • Xc1: Xc1 value should matchthe Xc value in the power flow model, if not the same the then Xc1 parameter is autocorrected to the Xc value of the power flow model.
  • Kiv: If Kiv > 1/(2*TimeStep) then Kiv = 1/(2*TimeStep)
  • Kis: If Kis > 1/(2*TimeStep) then Kis = 1/(2*TimeStep)

Mult represents the user-specified value Minimum time constant size as multiple of time step option on the Validation page of the Transient Stability Dialog

TimeStep represents the integration time step being used as described on TimeStep

Following treatment is handled during the transient numerical simulation

  • If SlowB > Vrmax, then Vrmax = SlowB or if SlowB < Vrmin, then Vrmin = SlowB
  • If Vref > Vefrmax, then Vrefmax = Vref or if Vref < Vrefmin, then Vrefmin = Vref
  • If Verr > Vemax, then Vemax = Verr or if Verr < Vemin, then Vemin = Verr
  • If Bpi > Bmax, then Bmax = Bpi or if Bpi < Bmin, then Bmin = Bpi

Model Equations and/or Block Diagrams

Parameters:

UVSBmax Maximum capacitive limit during undervoltage strategy
UV1 Under Voltage Setpoint 1, pu
UV2 Under Voltage Setpoint 2, pu
UVT Under Voltage Trip Setting Time, sec
OV1 Over Voltage Setpoint 1, pu
OV2 Over Voltage Setpoint 2, pu
UVtm1 Under Voltage Trip Time 1, sec
UVtm2 Under Voltage Trip Time 2, sec
OVtm1 Over Voltage Trip Time 1, sec
OVtm2 Over Voltage Trip Time 2, sec
Flag1 MSS Switching enabled(1) or disabled(0)
Flag2 Liner(0) or Non-linear(1) Slope
Xc1 Slope (nominal linear slope or first section of piecewise linear slope, pu/pu)
Xc2 Slope of second section of piecewise linear slope, pu/pu
Xc3 Slope of third section of piecewise linear slope, pu/pu
Vup Upper Voltage Break-point for non-linear slope, pu
Vlow Lower Voltage Break-point for non-linear slope, pu
Tc1 Voltage measurement lead time constant, sec
Tb1 Voltage measurement lag time constant, sec
Tc2 Lead time constant for transient gain reduction, sec
Tb2 Lag time constant for transient gain reduction, sec
Kpv Voltage regulator proportional gain, pu/pu
Kiv Voltage regulator integral gain, pu/pu
Vemax Max. allowed voltage error, pu
Vemin Min. allowed voltage error, pu
T2 Firing delay time constant, sec
Bshrt Short-term max. capacitive rating of the SVC, pu
Bmax Continuous max. capacitive rating of the SVC, pu
Bmin Continuous min. inductive rating of the SVC, pu
Tshrt Short-term rating definite time delay, sec
Kps Proportional gain of slow-susceptance regulator, pu/pu
Kis Integral gain of slow-susceptance regulator, pu/pu
Vrmax Max. Allowed PI controller output of slow-susceptance regulator, pu
Vrmin Min. Allowed PI controller output of slow-susceptance regulator, pu
Vdbd1 Steady-state deadband, pu
Vdbd2 Inner voltage deadband, pu
Tdbd Definite time deadband delay, sec
PLLdelay PLL delay in recovering if voltage remains below UV1 for more than UVtm1, sec
Eps Small delta added to the susceptance bandwidth, MVAr
Blcs Large threshold for switching MSS in capacitive side, MVAr
Bscs Small threshold for switching MSS in capacitive side, MVAr
Blis Large threshold for switching MSS in inductive side, MVAr
Bsis Small threshold for switching MSS in inductive side, MVAr
Tmssbrk MSS breaker switch delay, sec
Tdelay1 Definite time delay for large switching threshold, sec
Tdelay2 Definite time delay for small switching threshold, sec
Tout Discharge time for mechanically switched capacitors, sec