Dynamic Stability Features


  • Generator Models
    • Round rotor full sub-transient flux detail synchronous generator model with saturation
    • Salient pole full sub-transient flux detail synchronous generator model with saturation
  • Excitation System Models
    • Simple, single time constant excitation system
    • IEEE Type AC1A, AC6A, AC8B brushless excitation system
    • IEEE Type 1 and IEEE Type 2 excitation system
    • Fast, medium and slow response tunings in library
  • Governor System Models
    • Steam turbine, gas turbine, and Woodward diesel systems
    • Fast, medium and slow response tunings in library
  • Motor Models
    • Induction double-cage, full sub-transient, flux detail model with saturation
    • Synchronous salient-pole, full sub-transient flux detail model with saturation
    • Induction flux motor model includes option for additional stator flux dynamics
    • Includes modeling of starting and running loads, and auto-transfer of load
    • Synchronous motor includes field application at defined speed
  • Motor Load Models
    • Torque as a function of speed squared or cubed
    • Torque vs. speed as a digitized load model function
  • Detailed Model Library
    • Use our supplied data “as is” to do quick checks for a typical system
    • Add your own model data for your system, and future analysis
    • Organize data in user-specified categories for quick locate and import
    • Data sets: over 70 complete model examples
  • Network Model
    • Uses EasyPower’s network model already defined in your database
    • Performs a constant impedance network analysis
    • Auto-transformer tap operation suppressed
    • Utilities modeled as short circuit impedance sources (infinite inertia)
    • All static loads modeled as constant impedance
    • Resolves network to update conditions for changes in induction motor vars, based on requirements of machine equations at initialization
    • While in Dynamic Stability focus, system can be changed via breaker operations (right mouse click on breaker) and power flow initial conditions resolved before a simulation


  • Start any single motor, including automatic changes from starting to running load
  • Start entire group of motors via breaker operation
  • Integrated with Scenario Manager™ for quick simulation of various alternatives
  • Modify automatic double-click controls (simulation length, time of action, etc.) to fit your simulation needs
  • Suppress message log as desired with three categories: initialization, runtime, and protective device action messages
  • Modify simulation time step to suit simulation needs
  • Enable/disable all automatic contactor, protective device, and ATS (automatic transfer switch) actions
  • Specify plot length by number of points
  • Automatically copies results to Windows® clipboard for use in any spreadsheet

Fast Double-Click Functionality

  • Open/close/simulate any switching devices
  • Bus fault/simulate any bus
  • Transfer/simulate any ATS
  • Step/simulate any generator for open circuit step test
  • Step/simulate any generator for governor load step test

Protective Device Functionality

  • Includes protective device actions for all devices already defined in database
  • Adds automatic contactor dropout functionality
  • Adds ATS auto-switching functionality
  • Protective device actions can be easily included or excluded from a simulation with a single option setting

Scripting Engine

  • Define a script to perform any type of simulation action in time
  • Allows open/close of any breaker and transfer of any ATS
  • Includes fault application impedance and duration
  • Includes “Run To” and “Run For” time features
  • Start, trip, and re-close any motor or group of motors
  • Create complete motor-sequencing simulation
  • Perform reduced voltage starts via network changes

One-line Integration

  • Display of one-line at initial condition upon entry to Dynamic Stability focus
  • Display of system conditions at end of simulation
  • Display of system conditions at any point, using simulation step feature
  • Graphical symbol morphing to indicated inclusion of stability data


  • Includes up to 10 plots, 5 traces per plot, of model and network items
  • Monitor motor: terminal voltage, current, watts, and vars; electrical and load torque; speed; and power angle
  • Monitor synchronous machine: terminal voltage current, watts, and vars; speed; electrical torque; mechanical power; field voltage; angle; power angle; D-Axis current; Q-Axis current; D-Axis sub-transient flux; Q-Axis sub-transient flux
  • Monitor bus: voltage, angle, frequency, and fault current
  • Monitor network branch and shunt device: kW, kVar, amps, voltage
  • Plot definitions use quick and intuitive equipment selection right off the one-line

Detailed Message Log

  • Detailed message log tracks all system behavior at initialization and runtime
  • Initialization messages help you quickly debug an ill-defined system model or data
  • Run-time messages show all script actions and automatic switching actions
  • Run-time messages show protective device pickup, reset, trip and lockout actions

Model Data Sheets

  • Model data sheets can be quickly printed
  • Print a single model, or an entire group of equipment items with quick one-line select
  • Exciter and governor data sheets include graphic of model block diagram

Built-In Automatic Control

  • Automatic detection of numerical instability, allowing quick system reset
  • Automatic internal model sub-integration to minimize numerical instability issues at typical simulation time steps
  • Improved modified Euler integration technique
  • Simulation of stator flux transients (dψ/dt terms) using differential instead of integral technique, eliminating numerical instability issues in the motor’s fast time constant stator equations at normal time steps (half to quarter cycle)
  • Detailed data checking of parameters when entering in the database
  • Automatic detection of invalid or insolvable system power flow when entering Dynamic Stability focus

Control Interface

  • Easy-to-use dynamics focus toolbar with fewer buttons but more capabilities
  • Select scripts to run simulations directly from a drop-down list in the toolbar
  • Pause any simulation for termination
  • Restart any paused simulation
  • Reset to initial conditions at any time during simulation
  • Enable/disable results on the one-line view just like in power flow focus

Induction Motor Parameter Derivation

  • Induction motor parameter derivation tool that lets you determine detailed flux model parameters using your running and starting conditions, and your machine torque speed curve
  • Automatic minimization technique used to locate best parameters to match your data
  • Gravity points help to pull the derivation towards your desired curve
  • Integrated digitizer with spline curves allows overlay of a quick drawing of torque speed curve over a scanned image of actual data
  • With one mouse click, import the derived data directly into your database
  • Easily copy your derived data into the user library

EasyPower Dynamic Stability requires PowerFlow™ to operate and Protection & Coordination™ for all protective device simulations.

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