Simulator 16 User Guide - PowerWorld

Integrated Topology Processing: Full-Topology Model
Real-time applications require modeling the power network at a level of detail that includes all the
switching devices such as circuit breakers and disconnects and other very low-impedance branch
devices. For instance, an operator must have information about specific breaker statuses to coordinate
device maintenance procedures.
These detailed models are referred to as “node-breaker” or “full-topology” models. This type of model
cannot be solved directly in conventional planning applications because of the large number of very
low-impedance branches resulting from the switching devices. The power flow would be forced to use
an Ill-Conditioned Jacobian matrix if these low-impedances were directly modeled. In order to solve
the power flow on a full-topology model, Simulator dynamically obtains a Consolidated Representation
of the power network by dynamically moving the device connection pointers.
Simulator models all type of branch objects as transmission line records. To aid in the consolidation,
additional input parameters are necessary to properly identify the type of branch object that is being
modeled and determine whether or not that branch can be eliminated during consolidation. These
fields are accessible from the Topology group in the Available Fields for the Line and Transformer
Display in the Model Explorer. Two relevant input fields needed for Topology Processing are:
Branch Device Type
Type of branch specified as Transformer, Line, SeriesCap, Breaker, Load Break Disconnect,
Disconnect, ZBR (Zero-Impedance Branch), Fuse, and Ground Disconnect.
For brevity in the context of tools that either automatically switch or identify breakers to either
open or close a device, the term breaker is used to indicate any type of device that can be
switched automatically. This includes branch devices of type Breaker and Load Break Disconnect.
Allow Consolidation of Branch
This is a YES or NO field, which tells Simulator to eliminate closed switching devices and other
very low-impedance branches from the network model during consolidation. Only branches that
have a Branch Device Type equal to Breaker, Load Break Disconnect, Disconnect, ZBR, Fuse,
or Ground Disconnect can be consolidated. If an element is of this type and is set not to be
consolidated, it will be preserved in the model and its default impedance value will be used in the
power flow equations. In the context of consolidation, the term breakeror switching device can
be used to include any of the device types that can be consolidated.
There are other instances in which a branch that is marked as allowed to be consolidated will not
be consolidated:
Branches that are area tie lines
Branches that are connected to a multi-terminal dc line converter
Branches that are part of a Model Condition
Branches that are part of a Model Expression
Branches that are part of a Post Power Flow Solution action
Branches that are part of Transient Stability event
Branches that are part of a contingency action if not using Incremental Topology Processing
Branches that are part of an interface unless the branch is in series with a device that
cannot be consolidated, e.g. transformer, line, load, generator, etc. The interface will be
automatically modified to monitor the series device instead of the branch so that the branch
can be consolidated.
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