Dynamic Events

Transient stability simulation is designed to simulate electromechanical transients due to a large disturbance (Dynamic Event) or a sequence of such events in electric power systems. This reference manual presents InterPSS transient stability simulation dynamic event implementation technical details. Please refer to the InterPSS Transient Stability User Guide for information regarding how to define these dynamic events for a transient stability simulation run.

Introduction

InterPSS currently supports two types of generic dynamic events:

• Change Event: : Including bus fault, branch fault, and branch outage. These kind events normally result in large disturbance to the operation of power system. You can define multiple such events in a simulation case, such as a branch fault followed by a branch outage to clear the fault. Please note: currently InterPSS core library can handle only one unsymmetrical fault at any simulation point.
• Adjustment Event : For describing auxiliary actions such as Load change, controller set point change.

InterPSS dynamic event can be defined as temporary or permanent.

• Temporary event : An event with a start time and a duration. After the duration, the event will be automatically cleared.
• Permanent event : An event with a start time and last forever.

By combination of these basic events, you can simulate more complex events. As shown in the following dynamic event edit panel, you can click the AddEvent button to add more events to your study case.

Change Event

Change Event includes bus fault, branch fault, and branch outage. These kind events normally result in large disturbance to the operation of power system. You can define multiple such events in a simulation case, such as a branch fault followed by a branch outage to clear the fault. Please note: currently InterPSS core library can handle only one unsymmetrical fault at any simulation point.

Bus Fault

Bus Fault is used to describe a dynamic event when a fault occurred at a bus and cause a large disturbance. The fault is cleared automatically after last for the duration, if it is not permanent.

• The fault starts from the Start Time. The fault will be cleared at Start Time + Duration.
• If the permanent option is selected, the bus fault will never be cleared. In this case you may need to use branch outage to isolate the fault.
• Fault could be 3-Phase (3P), Line-to-Ground (L-G), Line-to-Line (L-L) or Line-Line-to-Ground (LL-G).

Please refer to the InterPSS Short Circuit User Guide for more detailed information regarding how to define a bus fault.

Branch Fault

Branch Fault is used to describe a dynamic event when a fault occurred at a branch and cause a large disturbance. The fault is cleared automatically after last for the duration, if it is not permanent.

• The fault could be temporary (duration specified) or permanent.
• For temporary fault, the fault branch will be cleared (open) after t = Start Time + Duration.
• You can specify that the fault branch reclosure at a specified time. Reclosure Time must be large than Start Time+Duration.

Please refer to the InterPSS Short Circuit User Guide for more detailed information regarding how to define a branch fault.

Branch Outage

You can define a branch outage event, for example, to isolate a permanent bus or branch fault. You can also simulate a scheduled branch outage for line or transformer maintenance.

Select a branch and branch outage starting time. Branch outage is always permanent. Currently only three-phase branch outage is supported

Adjustment Event

Adjustment event is for describing auxiliary actions such as Load change, controller set point change.

Load Change

You can specify load change at a bus. The change factor in percent is with regarding to the bus initial load. The change could be at a fixed time, or trigged by low bus frequency or bus voltage. For low frequency change and low voltage change, a delay time in sec could be specified.

Controller SetPoint Change

Some time you might want make a step change to the set point or reference point of a controller to verify if parameters of the controller have been entered correctly. When you select the Disable Dynamic Events checkbox, the Controller SetPoint Change area will be enabled to allow you to define a controller set point change event.

• Machine : Select a machine where you want to make set point change
• Controller : List of all controllers on the selected machine
• SetPoint Value Change : Set point/reference point change value
• Absulte or Delta : Specify if the change is absolute or delta - a change to the steady-state value, which is calculated during the initialization process.