Simulator 16 User Guide - PowerWorld

When this option is checked, an estimate of the voltage at time step will use the voltage at the
previous three time steps to estimate what the next voltage will be. This essentially models the
voltage as a quadratic function of time based on the last three time steps and creates an
estimate of what the next voltage will be. This greatly aids in the initial guess sof the network
equation voltages at a time step and helps speed up the simulation.
Inner Loop Mismatch Scalar
PowerWorld Simulator uses a second order Runge-Kutta integration method. As a result network
equation solutions are sometimes done at intermediate time steps as part of the integration
method. Specifying a scalar here which is larger than 1.0 will allow those intermediate network
equation solution to have a larger mismatch.
Infinite Bus Modeling
Select whether or not to use infinite buses. If using infinite buses, the power system slack bus(es)
will be used as the infinite buses. If not using infinite buses, then an Angle Reference must be
selected on the Result Options. At infinite buses the angle does not change. When using infinite
buses, these are used as the angle reference.
Default Load Model
Specify what load model to use by default in the transient stability simulation when the load does
not have a load model characteristic defined. Normally it is best to define a load characteristic model
specifically (it is even possible to define a load characteristic model which applies to the entire case),
but if one is not specified this default will be used.
Minimum Per Unit Voltages for
When modeling loads as Constant Power Models or Constant Current Models, the load will
start to fall off by a particular function if the voltage falls below the specified value. The values
specified here are the same as the values for minimum voltages specified on the Power Flow
Solution Advanced Options page found under Simulator Options. Clicking the Change button will
open the Power Flow Solution Advanced Options page.
Ignore Speed Effects in Generator Swing Equation
The generator swing equation includes a term divides the Mechanical Power by the per unit speed of
the generator. Checking this box will ignore this speed effect. Normally you should not ignore this
effect.
Governor Fast Valving
A few specific governor models such as TGOV3 include an effect called Fast Valving. This option
specifies at what time the fast valving option is initiated. After choosing when you would like it to
initiate you then specify either a frequency deviation in rad/sec or a time in second as the parameter
Fast Valving Parameter (rad/sec or sec).
Exciter Saturation Model
Option to specify the type of saturation function to use for an exciter model. Choices are Quadratic
(GE Approach), Scaled Quadratic, or Exponential. When loading a PSLF DYD file it defaults to the
Quadratic exciter saturation function. When loading a PSS/E DYR file it defaults to the Scaled
Quadratic exciter saturation function. When loading a IPF SWI file it defaults to the Exponential
exciter saturation function.
Integration Method
Option to specify whether to use the Second Order Runga-Kutta Order 2 (RK2) or Euler's method for
the integration time step.
©2011 PowerWorld Corporation
1558