Transient Mode

Command options

The following list of global variables can help debug issues with transient mode.

deltamode_forced_always (default: FALSE)

Once delta mode is entered, prevents a return to quasi-static mode.

If set to TRUE, once transient mode is entered, it will remain in that mode until the simulation ends. Defaults to FALSE so transitions to and from transient mode can occur. This functionality is mainly to test longer-term dynamic behaviors, and to help debug transitions. It is not recommended to use this feature regularly.

deltamode_forced_extra_timesteps (default: 0)

Sets the number of forced extra delta timesteps to execute before returning to steady state.

When all objects supporting transient mode agree to return to quasi-static mode, this flag forces as many extra timesteps transient mode as the user defines. It is used to catch some slower behavior in transient mode models that may be delayed in its impact.

deltamode_iteration_limit (default: 10)

Sets the maximum number of times interupdate can iterate on the current fixed timestep of transient mode.

The deltamode_iteration_limit is used to prevent an object from locking GridLAB-D™ in a reiteration loop during interupdate passes of transient mode.

deltamode_maximumtime (default: 3600000000000)

Establishes the maximum time that a subsecond (delta mode) simulation can run without returning to event mode

The value of deltamode_maximumtime is given in nanoseconds. When the defined time elapses, the transient mode simulation will stop and return to quasi-static mode regardless of whether the affected modules have all indicated that event mode is permissible. The default value is one hour. It is assumed that most models will have some significant events within at least one hour. Values that may also be used frequently are one minute (60000000000) or one second (1000000000). This is intended to prevent a runaway simulation. If the simulation needs to return immediately to quasi-static mode it will do so without advancing the clock provided at least one of the module indicates that transient mode is desired.

deltamode_preferred_module_order (default: TRUE)

Controls the execution order of some modules in transient mode, regardless of the order in the GLM.

Prior to Version 4.3, transient mode executed a call for modules in the order they were loaded in the GLM. If the GLM order was not correct, it could result in out-of-step updates or what appeared to be delayed responses in transient mode models. Setting this to TRUE forces an update order to prevent this from happening, regardless of the load order in the GLM. When set to FALSE, the GLM order is used again. If set to TRUE, the following order is used: Tape, Connection, Reliability, Powerflow. Any other modules are loaded after this sequence, in the order they appear in the GLM.

deltamode_timestep (default:10ms)

Controls the fixed timestep of transient mode.

The deltamode_timestep is used to control the timestep of transient mode simulation.

deltamode_updateorder

Global variable indicating the order in which modules are updated in transient mode simulations.

The deltamode_updateorder global variable indicates the order which modules receive transient mode update requests from the main solver. The order in which modules receive the update is determined by the order in which modules are loaded by the GLM file. Changing this variable will not affect the simulation update order. The value of the deltamode_updateorder global variable is not set until the simulation initialization process has completed. As a result, it cannot be used while the GLM file is being loaded.