Simulator 16 User Guide - PowerWorld

generators in the defined group that are on AGC control are allowed to participate in the transfer.
Each generator participates in the transfer in proportion to its participation factor. When injection
groups are selected to be either the Seller or Buyer, only on-line generators and loads defined with
the injection group are allowed to participate in the transfer. Each element participates in the
transfer in proportion to the participation factor defined with its participation point in the injection
group. When a single bus is selected as the Seller or Buyer then all of the power injection change
needed for the transfer comes from that bus. It does not matter if there is a generator or load at
that bus. When the slack is selected for the Seller, then all of the power injection change needed for
the seller side of the transfer comes from the island slack bus for the island in which the Buyer
belongs. When the slack is selected as the Buyer, then all of the power injection change needed for
the buyer side of the transfer comes from the island slack bus for the island in which the Seller
belongs.
Generator and load MW limits are not enforced regardless of the type of buyer and seller. Error
messages will be displayed if the Seller and Buyer are not both completely contained within the
same electrical island.
Reverse Buyer/Seller Button
Click this button to reverse the direction currently shown. The buyer becomes the seller, and the
seller the buyer.
Linear Calculation Method
The ATC analysis tool can use either a Lossless DC or Lossless DC with Phase Shifters
calculation method for obtaining the ATC results.
If you select the Lossless DC option, branch flow sensitivity is calculated by estimating the real
power that flows through the monitored element only from the difference in angles measured across
its terminals.
The Lossless DC with Phase Shifters method, a modification to the lossless dc approximation, takes
into account phase shifter operation. It is especially useful when the ATC tool continually reports
overloads on branches that obviously will not overload because of the operation of a phase shifting
transformer. This method assumes that the phase shifter angles may change to any value to ensure
that the line flow on those lines does not change.
The Linearized AC method is not yet available.
Enable Phase Shifters Post-Contingency
This option becomes enabled when you choose the Lossless DC with Phase Shifters linear
calculation method. It allows you to choose whether or not phase shifter control should be enforced
during post-contingency ATC calculations. When this option is checked, it is assumed that phase
shifter angles may change to keep the line flow from changing after the contingency has been
applied. Otherwise, it is assumed that phase shifters only maintain the flow in the pre-contingency
state and the angles do not change in the post-contingency state. Base case (pre-contingency)
transfer limiters will still be determined with phase shifters enforced, regardless of the setting of this
option when the Lossless DC with Phase Shifters option is checked.
Include Contingencies Check Box
Check this box to include contingencies (inserted or loaded using the Contingency Analysis Tool) in
the ATC analysis. Note that minimizing the number of contingencies considered greatly improves
solution speed as well as computer memory requirements for doing ATC Analysis. Therefore, be
careful in choosing which contingencies to use with the ATC tool. Setting the Skip field to YES for a
particular contingency will exclude it from the ATC analysis.
The ATC tool uses the same contingency records as the contingency analysis tool. Contingency
results may be invalid following ATC analysis. If necessary, save contingency results to an auxiliary
file prior to running the ATC analysis.
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