When in the DS Focus, the DS Options Dialog can be reached by clicking on DS Options. The dialog includes four main sections with settings that supply control over the DS Engine. Each setting is described in detail in this section.
2.10.1 Control Screen
The Control Section includes settings that control the foundational elements of a DS simulation, as well as control display and messaging (Figure 30). The settings are defined as follows:
Simulation Run Control
Solution Time Step The defined time step, in seconds, of the simulation.
The default value is 1/10th of a half cycle, and is set low on purpose, to create stable numerical conditions for induction motors under starting and spin-down conditions.
Step Run Delta Time The time duration, in seconds, over which a simulation is run and then paused after the Simulation Step button is pressed. The default value is 0.1 seconds.
Enable all protective devices If enabled (default), then relays, fuses and low voltage breakers will sense and trip in a simulation. For this feature to be active the user must own the Power Protector feature of EasyPower.
Enable contactor action If enabled (default), then contactors will sense and trip in a simulation. For this feature to be active the user must own the Power Protector feature of EasyPower.
Enable ATS If enabled (default), then ATS’ will sense and transfer in a simulation. For this feature to be active the user must own the Power Protector feature of EasyPower.
Include Stator Flux Dynamics
Induction motor models If enabled (not default), then additional stator flux dynamics (the time build-up of flux in the stator windings) are included for all induction motors in the simulation.
Message Log Control
Log model messages at initialization If enabled (default), then all initialization messages from DS models appear in the Message Log.
Log model messages during run If enabled (default), then all run time messages from DS models appear in the message log.
Log protective device trip messages If enabled (default), then all run time message from protective devices will appear in the message log.
Figure 30. Dynamic Stability Options – Control Tab.
Initialization Control
Maximum Allowed DState The maximum allowed DState, in per unit, that triggers an initialization error message in the Message Log if exceeded.
Entering Stability Focus
Automatically arrange windows If enabled (default), then the Oneline Window, Message Log Window, and DS Plot Window will auto-arrange all in view. You may also press the F8 key at any time to perform the same auto-arrange.
Show plot window If enabled (default), then when DS Focus is entered the DS Plot Window will automatically appear. If not enabled, the DS Plot Window will automatically appear whenever a simulation is run or step-run.
Show message log If enabled (default), then when DS Focus is entered the Message Log Window will automatically appear. If not enabled, the DS Plot Window will automatically appear whenever a simulation is run or step-run.
2.10.2 Double-Click Screen
The Double-Click Control Tab includes settings that control all of the double-click actions that are performed on the oneline (Figure 31). The settings are defined as follows:
Generator’s Exciter Symbol to Step
VRef Step The step voltage, in percent, applied to the reference of the excitation system to be stepped.
Initial Terminal Voltage The initial terminal voltage of the generator, in percent, used to initialize the generator machine model and the excitation system model.
Simulation End Time The total simulation time length in seconds.
Delay Time Length The time duration, in seconds, where the simulation runs steady-state before any actions are taken. After this time, the excitation system voltage reference (VRef) is stepped.
Generator’s Governor Symbol to Step
Initial Load The initial loading of the generator, in percent.
Load Step The step load, in percent, applied to the terminals of the generator.
Simulation End Time The total simulation time length, in seconds.
Delay Time Length The time duration, in seconds, where the simulation runs steady-state before any actions are taken. After this time, the load on the generator’s terminals is stepped.
Breaker or Switch to Open
Simulation End Time The total simulation time length, in seconds.
Delay Time Length The time duration, in seconds, where the simulation runs steady-state before any actions are taken. After this time, the switching device is opened.
Figure 31. Dynamic Stability Options – Double-Click Control Tab.
Breaker or Switch to Close
Simulation End Time The total simulation time length, in seconds.
Delay Time Length The time duration, in seconds, where the simulation runs steady-state before any actions are taken. After this time, the switching device is closed.
ATS to Transfer
Simulation End Time The total simulation time length, in seconds.
Delay Time Length The time duration, in seconds, where the simulation runs steady-state before any actions are taken. After this time, the ATS is transferred.
Bus to Fault
Fault Resistance The fault resistance, in ohms.
Fault Reactance The fault reactance, in ohms.
Simulation End Time The total simulation time length, in seconds.
Delay Time Length The time duration, in seconds, where the simulation runs steady-state before any actions are taken. After this time, the bus is faulted.
Fault Time Length The time duration, in seconds, that the fault is left on the bus. The fault is applied after the Delay Time Length, and is removed after Fault Time Length has elapsed. If you desire to have protective devices perform all fault clearing, we recommend setting this value longer than the Simulation End Time, so that the fault is never removed from the bus over the entire simulation. If you set this value equal to the Simulation End Time, then the last time step of the simulation, and the resulting end-of-simulation network results displayed on the oneline will present the system with the fault removed.
2.10.3 Plot Output Screen
The Plot Output Tab includes three settings that control plotting in the DS Plot Window (Figure 32). The settings are defined as follows:
Figure 32. Dynamic Stability Options – Plot Output Tab.
Maximum plot size The maximum number of points for each curve presented in the DS Plot Window, and the tabulation of data in the DS Plot Window spreadsheet. Note: if the
Overlay Plot Curves If enabled (not default), then the min and max scales of all plots (when in auto-scale mode) in the DS Plot Window are determined so that all curves are in a maximum view mode. In most cases curves will overlap somewhat. If disabled (default) then all min and max plot scales of each plot curve will be determined so that no overlap in the curves occurs. The plot is broken into vertical sections depending upon the number of curves.
2.10.4 Arc Flash Screen
The Plot Output Tab includes three settings that control plotting in the DS Plot Window (Figure 33). The settings are defined as follows:
Use Arc Flash Simulation for Faults If enabled (not default), this will use IEEE 1584 arc flash equations to apply a fault, thus including fault current limiting action by the arc.
Arcing Current This percentage is applied to the calculated arcing current and is typically used to simulate conditions with the 85% of bolted fault current method typically used in arc flash calculations.
Working Distance This distance is used to calculate PPE from the arc flash results.
Maximum Time If the arc is not cleared by a protective device, then this time will be used to remove the arcing fault. Since applying an arc flash significantly increases the time it takes to perform a simulation during the arc, the value will allow you to curtail simulations that may never clear (i.e. if protective devices were not specified).
Figure 33. Dynamic Stability Options – Arc Flash Tab.