The IEEE 14 bus system (download from here), as shown in the following diagram, is used as an example to walk you through how to use InterPSS Interactive to perform power trading analysis. The analysis is based on InterPSS DC Loadflow implementation, where you can find DC Loadflow theory discussion.
(Click to enlarge the picture)
There are three generators, at bus 1, bus 2 and bus 3, in the generation area. Load are in the load area, as bus 12, bus 13, bus 14 and other buses. Branches (5->6, 4->9 and 4->7) forms an interface from the generation area to the load area. The sum of shift factors from a bus in the generation are to a bus in the load area should be equal to 1.0.
DC Loadflow allows you to find out the loading condition on each branch in a power network. Type the following commend to run DC Loadflow analysis
(TODO: Add Sample code)
DC Loadflow Results
Bud Id VoltAng(deg)
=================================
Bus1 0.0000
Bus2 -5.01343
...
FromId->ToId Power Flow(Mw) MWLimit Loading% Violation
=========================================================================
Bus1->Bus2(1) 147.88 0.00
Bus1->Bus5(1) 71.12 0.00
...
Very often, one would like to investigate the contribution of a particular generator bus, supply power to a set of load buses, to the power flow on a branch or an interface, which is defined as a set of branches, by calculating the generator shift factor.
(TODO: add sample code)
Monitoring branch Bus5->Bus6(1)
GFS(Bus3) = 0.5647421515129025
GFS(Bus2) = 0.5776439628218537
Monitoring branch Bus4->Bus9(1)
GFS(Bus3) = 0.1586910205386520
GFS(Bus2) = 0.153987138436282
Monitoring branch Bus4->Bus7(1)
GFS(Bus3) = 0.2765668279484458
GFS(Bus2) = 0.2683688987418648
Interface 'Interface-1' Shift Factor
GFS(Bus3) = 1.0000000000000004
GFS(Bus2) = 1.0000000000000004
Based on the base case, one might want to study the impact of a proposed trade on the branch loading. To define a trade, one needs to define three pieces of info:
1) Generator Group: generation injection points. df stands for distribution factor. The sum of all df should be equal to 1.0
2) Load Group: load withdraw points. Again the sum of all df should be equal 1.0
3) Trade and Monitoring Branches: Define trade amount and monitoring branches. The de-rating factor are applied to the branch MW limit.
(TODO: add sample code)
Trade 'Trade-1' Amount (MW) : 50.00
Branch Id ShiftFactor BaseCaseMw PredictedMW MWLimit Loading% Violation
========================================================================================================
Bus5->Bus6(1) 0.510 42.08 67.56 70.00 96.5
Bus4->Bus9(1) 0.179 16.63 25.57 50.00 51.1
Bus4->Bus7(1) 0.312 28.99 44.57 50.00 89.1
There is no violation for the 50 mw proposed trade. If the trade amount increased to 100 mw, the results are as follows with branch MW limit violation:
Trade 'Trade-2' Amount (MW) : 100.00
Branch Id ShiftFactor BaseCaseMw PredictedMW MWLimit Loading% Violation
========================================================================================================
Bus5->Bus6(1) 0.510 42.08 93.04 70.00 132.9 x
Bus4->Bus9(1) 0.179 16.63 34.51 50.00 69.0
Bus4->Bus7(1) 0.312 28.99 60.15 50.00 120.3 x
Very often you may want study the impact of lose of one line to the load condition of near-by lines or other lines in an interface. For example, in the IEEE 14-bus system, if the 4->7 line lost, the flow on the line will be re-distrubuted to line 4->9 and 5->6. You can create an outage together with monitoring branch set, as follows:
(todo: Add sample code)
As can be seen in the following output, the lose of branch 4->7 has created over-loading situation on branch 4->9 and branch 5->6. The impact of line outage to other branches in the system is calculated based on the LOSF (Line Outage Shift Factor) by de-rating the branches MW rating limit.
Line Outage 'outage-1' Branch Id: Bus4->Bus7(1)
Branch Id ShiftFactor ShiftMwFlow MWLimit DeratedLimit Loading% Violation
========================================================================================================
Bus4->Bus9(1) 0.508 16.63 50.00 13.12 126.8 x
Bus5->Bus6(1) 0.492 42.08 70.00 34.26 122.9 x
DeratedLimit : Branch MWLimit - Branch base case MW flow