Why Create These Factors?

PSS™MUST has many functions that can help you to review these factors. For more details, please, review section 6.1 in the PSS™MUST manual. Examples below will describe mostly frequently asked questions about TDF factors.

1. How to find the impact of a transaction on all flowgates?
   You should use the "Impact analysis" function on monitored elements, define the study transfer of the interest, and then create a report for all flowgates.

2. How to find flowgates that are mostly impacted by a selected transaction?
   You should use the "Impact analysis" function on monitored elements, define the study transfer of the interest, and then create a report only for those flowgates, which are impacted above a user defined cutoff using the "flowgates impact" report. You may want to check the option to sort reported flowgates by the study transfer impact.

3. How to find all possible transactions that have the most adverse impact for a selected flowgate?
   You should use the "Sensitivity Analysis For All Transactions". Then using Excel filters select only those transactions that have impact above some cutoff value.

4. How to find the most adverse impact for a selected flowgate transaction from my list of transactions?
   This is similar to the answer above, but you should use the "Sensitivity Analysis For Transactions" defined via the PSS™MUST Transaction Scheduling Function. You have to define a set of transactions prior to the execution of the sensitivity analysis function.

5. How to find generators within selected control areas, which have the most adverse impact on a selected flowgate?
   Define a subsystem, which includes all generators of interest. Then use the "Sensitivity Analysis Report for Subsystem Participation" points and sort this report by the impact factors. The "best" and the "worst" generators will be at the top or bottom of the sorted report. The maximum redispatch impact within the region of interest, defined as the generations redispatch between the "best" and the "worst" generators, can be estimated by the difference in the corresponding sensitivity factors.

6. How to find all control areas, for which different assumptions in generator scaling can yield different TDF factors?
   You should create a "single monitored element" detailed sensitivity analysis report for a selected flowgate. This will provide you with the possible spread in distribution factors within every control area.
   

7. How to find which control areas have the largest impact on selected flowgate(s)?
   Create sensitivity report for all subsystems, then sort by monitored element ranking all subsystems by the impact on a selected flowgate. Subsystems with the largest and smallest reference distribution factors have the most adverse impact on a flowgate. Subsystems with similar factors have the same impact. Impact of the transaction between two subsystems can be estimated by the difference in the reported factors.

8. Can PSS™MUST create a table with ALL TDF factors for all subsystems?
   Unfortunately no. This would result in a very large three-dimensional table for all possible pairs of transactions on all flowgates (100x100x700 where 100 is the number of subsystems, 700 is the number of NERC flowgates). This table would be too large to be of practical use. Instead, PSS™MUST can create the full table of reference TDF factors with respect to some reference subsystem (or swing bus). To create this table, list all flowgates, highlight and then create a designed sensitivity report. This table of factors can be easily embedded into other applications. This type of table was used by the NERC interim IDC.

9. What are the reference bus or reference subsystem factors?
   Reference bus or subsystem factors are the factors computed for the transfers from defined subsystems to a system swing bus or user designated reference subsystem used as an opposing (buying) subsystem. Reference TDF or GSF factors allow storing these factors in a much more compact form than saving explicit TDF or GSF factors for all possible combinations. It is very easy to compute TDF or GSF factors using available reference factors as it is shown below:
   
   TDF(Source,Sink,Fgate)=refTDF(Source,Fgate)-refTDF(Sink,Fgate)

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October 12, 2006 03:09 PM			©2010 Siemens Energy, Inc., Siemens Power Technologies International (Siemens PTI) Schenectady, NY, USA			E D SE PTI