Load Characteristic Model: CIM6

 

Following checks and corrections are applied during Validation and AutoCorrection.

  • R1: 1) If motor is not Double Cage or Type 1, then if circuit parameters result in a Tp time constant which is too small then set R1 to a multiple of Tp/(Minimum time constant size as a multiple of time step). 2) If motor is Double Cage or type 2, then if circuit parameters result in a Tpp time constant which is too small then change the motor to single cage by setting R2 and X2 to zero only if Tpp is less than Half the Minimum time constant size as a multiple of time step, and if not just set R1 to a multiple of Tpp/(Minimum time constant size as a multiple of time step).
  • R2: 1) If motor is Double Cage and Type 1, then if circuit parameters result in a Tpp time constant which is too small then change the motor to single cage by setting R2 and X2 to zero only if Tpp is less than Half the Minimum time constant size as a multiple of time step, and if not just set R2 to a multiple of Tpp/(Minimum time constant size as a multiple of time step). 2) If motor is Double Cage and Type 2, then if circuit parameters result in a Tp time constant which is too small then set R2 to a multiple of Tpp/(Minimum time constant size as a multiple of time step).

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

Model Equations and/or Block Diagrams

-Model is the same as CIM5, except for the load torque.

-Load Torque = T(Aω^2 + Bω + C0 + Dω^E). For motor starting T = TNOM. For online motors, T is calculated during initialization

Parameters:

IT 1: Motor type 1; 2: Motor type 2
Ra Armature Resistance in per unit on machine MVABase
Xa Leakage Reactance in per unit on machine MVABase
Xm Magnetizing Reactance in per unit on machine MVABase
R1 Rotor Resistance in per unit on machine MVABase
X1 Rotor Reactance in per unit on machine MVABase
R2 Second Winding Rotor Resistance in per unit on machine MVABase
X2 Second Winding Rotor Reactance in per unit on machine MVABase
E1 E1
SE1 SE1
E2 E2
SE2 SE2
Mbase When MBASE = 0, motor MVA base = PMULT x MW load. When MBASE > 0, motor MVA base = MBASE
Pmult Pmult
H H (inertia, per unit motor base)
Vi Per unit voltage for dropping induction motor
Ti Time needed for voltage to remain below Vi for dropping induction motor, cycles
Tb Breaker delay for tripping, cycles
A Equation parameter
B Equation parameter
D Equation parameter
E Equation exponent
C0 Equation parameter
Tnom Tnom, Load torque at 1 pu speed (used for motor starting only) (≥ 0)