FixedNum Bus and RAW Format

 

Support for this was added in Version 24. In Simulator Version 23 we could read these files, but we would not maintain the FixedNumBus structures in Simulator and the nodes inside substation would be assigned an unused number.

There are some fundamental data structure differences between PowerWorld's data structure and the structure described in the RAW file format. For example, Substation objects in PowerWorld Simulator have no bearing on the existing of full topology models. Substation objects have existed in PowerWorld Simulator since about 2000 and a Substation is purely a grouping of Bus objects. You can create substations for your entire system model and assign each bus to a substation even in a case that does not model any switching devices. In the RAW file data structure however, the existance of a substation is intertwined with the concept of topology and nodes. A general summary of the structure

 

PowerWorld Simulator

RAW file data structure

  • Bus

    • Number.

      • For RAW file PowerWorld assigns a number equal to
        1000000*SubNodeNum + FixedNumBus
        (except for SubNodeNum=1 is FixedNumBus)

    • Can be assigned a FixedNumBus

    • Can be assigned to a Substation

    • Assigned a SubNodeNum between 1-999 to maintain RAW file compatiblity. This is not required for PowerWorld.

  • Branch

  • Substation objects

  • A Bus described at the top of the RAW file actually represents a group of Nodes (PowerWorld would call this a FixedNumBus). In this description below we will call it a PSSE_Bus.

    • A PSSE_Bus can have multiple voltage phasors associated with it as the PSSE_Bus can be split inside the substation

    • PSSE_Bus has a number between 1-999999 which is unique

  • System Switching Devices are listed separately at the top of the RAW file similar to the way Lines and transformers are listed.

    • Each switching device has a "Device type" which is either a 1, 2 or 3. PowerWorld maps these types to 1=ZBR, 2=Breaker and 3=Disconnect

  • Substation objects are special structures at the bottom of the RAW file

    • Each substation has its own list of Nodes in it.

      • Each Node has a number between 1-999 that is unique within the substation

      • Each Nodes must be assigned to a one PSEE_Bus objects listed at the top of the RAW file. Every node assigned to a PSSE_Bus could have a different voltage phasor depending on the status of switching devices

      • Nodes in 2 different substations can not be assigned to the same PSEE_Bus

    • Each substation has a list of Substation Switching Devices. These devices must be between 2 nodes inside the substation and each of those nodes must be assigned to the same PSSE_Bus. If a switching device connects 2 different PSSE_Bus objects then it can NOT be list in this section and must instead be listed in the special System Switching Devices list mentioned above.

      • Each switching device has a "Device type" which is either a 1, 2 or 3. PowerWorld maps these types to 1=ZBR, 2=Breaker and 3=Disconnect

    • Every object that connects to any node in the substation must have additional records to represent the Terminal Data connection. Thus there are special entries for

      • 1 for each generator

      • 1 for each load

      • 1 for each switched shunt

      • 2 for each branch

      • 2 for each system switching device

      • 2 for each 2-winding transformer

      • 3 for each 3-winding transformer

      • 2 for each DC transmission line

      • and so on

As an example, consider the system topology depicted in the following image

 

RAW File Top portion for PSSE_Bus, Branch, System Switching Devices

Below is a concentration of only Substation 3053 which is represented in the RAW file data structure. The top portion of the RAW file contains the following

One Substation section at the bottom of a RAW file

At the bottom of the RAW file is then a section for Substation and then the Substation Nodes, Switching Devices and Terminal Data.

Substation Node Data

A close-up of the Substation Node Data is shown next and illustrates how some of the PSSE_Bus objects have been split into different electrical points and thus must include the voltage and angle in their definition. It also illustrates how PowerWorld assigned a bus number equal to

PowerWorld Bus Number = SubNodeNum * 1000000 + FixedBusNus.

 

 

 

Substation Terminal Data