QV Curves Options: Output
These options are found on the Output sub-tab located on the Options page of the QV Curves dialog.
Extra Monitoring File
During the analysis, there will be an extra file that gets created for QV results that has little to do with the settings on this page. This is the file used to store the Quantities to track. This file will always be created. There is no option that can be set that will prevent it from being created. By default this file will be named ExtraMonitoring.csv and will be stored in the current directory. If a filename is specified in the Save result in file box, the extra monitoring file will be named using the filename specified with _ExtraMonitoring appended to the filename. The file extension will be the same as that specified with the filename. Regardless of the specified file extension, this file will be a comma-delimited text file.
The results for the tracked quantities will also be stored in an auxiliary file if choosing to store the QV results to file. The extra monitoring file is not meant to replace this but to simply provide a format that is easy to load into Excel for analysis outside of Simulator.
Save results in comma-delimited format
A comma-delimited file format for QV results exists for easy import into a spreadsheet. This file format cannot be loaded back into Simulator. If this functionality is required, it is suggested that the results be saved in an auxiliary file. To save the results to an auxiliary file, click the Save... button found at the bottom of the QV Curves dialog. The values saved to the comma-delimited file are the same values that are saved in the SUBDATA section for QVCurve data saved to an auxiliary file.
The comma-delimited file is grouped into sections for each scenario. Each scenario is identified by a header than indicates the bus and either base case or contingency identifier. The header is followed by a line that provides the field order of the actual data. The field line is followed by lines of data. Each scenario grouping is separated by a blank line. All results are sorted by the voltage setpoint.
The fields have the following meaning:
V(PU) - per-unit voltage set-point
Q_sync(MVR) - output of the fake generator (synchronous condenser)
Q_shunt(MVR) - sum of bus shunt, on-line switched shunt, and on-line generator Mvar (excluding the fake generator)
Q_tot(MVR) - Q_sync + Q_shunt
Q_res(MVR) - available reserve at the bus
Q_tot_res(MVR) - Q_sync + Q_shunt + Q_res
Here is an example of the comma-delimited file:
**BUS** 3 (Three_138.0),**CASE** L_000001ONE-000003THREEC1
V(PU), Q_sync(MVR), Q_shunt(MVR), Q_tot(MVR), Q_res(MVR), Q_tot_res(MVR)
1.1000, 437.5849, 48.4000, 485.9849, 242.0000, 727.9849
1.0962, 419.8296, 48.0627, 467.8923, 240.3136, 708.2059
1.0862, 374.1186, 47.1898, 421.3083, 235.9489, 657.2572
1.0762, 329.2408, 46.3248, 375.5656, 231.6243, 607.1899
1.0662, 285.1944, 45.4679, 330.6623, 227.3396, 558.0020
1.0562, 241.9775, 44.6190, 286.5965, 223.0950, 509.6915
1.0462, 199.5884, 43.7781, 243.3665, 218.8904, 462.2568
1.0362, 158.0253, 42.9451, 200.9705, 214.7257, 415.6962
1.0262, 117.2866, 42.1202, 159.4069, 210.6011, 370.0079
1.0162, 77.3706, 41.3033, 118.6739, 206.5164, 325.1904
1.0062, 38.2757, 40.4944, 78.7701, 202.4718, 281.2419
0.9962, 0.0000, 39.6934, 39.6934, 198.4671, 238.1605
0.9962, 0.0000, 39.6934, 39.6934, 0.0000, 39.6934
0.9962, 0.0000, 39.6934, 39.6934, -119.0803, -79.3869
0.9862, -37.4572, 38.9005, 1.4433, -116.7015, -115.2582
0.9762, -74.0981, 38.1156, -35.9825, -114.3467, -150.3292
0.9662, -109.9612, 37.3386, -72.6225, -112.0160, -184.6385
0.9562, -144.9682, 36.5697, -108.3985, -109.7092, -218.1077
0.9462, -179.1652, 35.8088, -143.3564, -107.4264, -250.7828
0.9362, -212.5517, 35.0559, -177.4958, -105.1676, -282.6635
Save Results to File
Check this box to actually save the results to the file specified by Save results in file.
Save results in file
Specify the name and file path of the file to which to save the results. This option will be enabled when the Save Results to File option is checked. Click the Browse button to open a dialog that will allow selection of the file path and name.
Plot curves as they are computed
Check this box to draw and update QV curve plots during each step of the QV analysis process. In order to have QV curves automatically plotted for a contingency during each step of the analysis, the QV Autoplot field belonging to that contingency must be set to YES on the Contingency Analysis Dialog.
If curves are not plotted at they are computed, they can be easily created upon completion of the analysis from an option found on the Listing sub-tab on the Results tab.
When plotting V versus Q, treat Q as...
There are several options that determine how the Q quantity should be plotted on a QV curve. These options are applicable whether plotting the curves automatically as they are computed or plotting the curves upon completion of the analysis.
An example plot is shown below with examples of the plots that result from the four possible options for how to treat Q.
The output of the fictitious synchronous condenser (Qsync)
Select this option to treat Q as the output of the fake generator (synchronous condenser) only. This is the Q_sync(MVR) curve shown in the example plot below.
The total reactive injection at the bus, including shunts but excluding load
Select this option to treat Q as the sum of the output of the fake generator (synchronous condenser), any on-line shunts, and any on-line Mvar generation other than the fake generator. Shunts include both bus shunts and switched shunts. This is the Q_tot(MVR) curve shown in the example plot below.
Include reserves (status = closed, generators on AVR, switched shunts not fixed)
Check this box to offset the Q values by the appropriate Mvar reserves values.
When the QV curve is traced for a given bus, any existing switched shunts on control at that bus are turned off control and any existing generators on AVR control at that bus are turned off control. The amount of Mvar support that these devices can provide is then recorded and determined at each voltage set-point. These are the reserves values. Only devices that are on-line and on control will be included. This means that for a generator the AVR status = YES and for a switched shunt the control mode must not be Fixed.
The amount of down (decrease) reserves at a given voltage set-point for a switched shunt is determined by the difference between the current nominal output of the shunt and its minimum nominal output multiplied by the square of the voltage set-point: (Nominal Mvar - Min Nominal Mvar)*V2. The amount of down (decrease) reserves for a generator at a given voltage set-point is the difference between the current output and the minimum Mvar output: (Mvar Output - Min Mvars). The amount of up (increase) reserves at a given voltage set-point for a switched shunt is determined by the difference between the maximum nominal output of the shunt and its current nominal output multiplied by the square of the voltage set-point: (Max Nominal Mvar - Nominal Mvar)*V2. The amount of up (increase) reserves for a generator at a given voltage set-point is the difference between the maximum Mvar output and the current output: (Max Mvars - Mvar Output). The total reserves of each type at any voltage set-point is the sum of reserves of that type for all qualifying switched shunts and generators at the studied bus.
Which type (up or down) of reserves to consider at a particular voltage set-point is determined based on the location of the voltage set-point relative to the base case operating voltage. When considering contingencies, the base case operating voltage is the voltage at a bus following implementation of the contingency but before any QV curve tracing is started. If the voltage set-point is less than the base case operating voltage, the up reserves are considered. This part of the curve represents an increase in the Mvar load at a bus. The difference in the bottom of the curve and the x-axis is the amount that the Mvar load at a bus can be increased before voltage collapse. Being able to inject additional Mvar through available reserves will further increase this margin. When plotting including reserves, the portion of the curve to the left of the base case operating point is then offset downward by the amount of up reserves that are available at each voltage set-point, thus increasing the margin before collapse. The portion of the curve to the right of the base case operating point is then offset upward based on the amount of down reserves available at each voltage set-point.
Instead of listing an absolute value of reserves available, the Q_res(MVR) value as reported with the QV output results (either comma-delimited file or auxiliary file) is reflective of the offset required when plotting the curve including the reserves.
When choosing to include reserves, the values that are plotted are either Q_sync_res(MVR) or Q_tot_res(MVR). The Q_sync_res(MVR) value is not included in the QV output results (either comma-delimited file or auxiliary file) but is equal to the sum of Q_sync(MVR) and Q_res(MVR): Q_sync_res(MVR) = Q_sync(MVR) + Q_res(MVR). Q_sync_res(MVR) represents the combination of selecting the option to plot The output of the synchronous condenser and including reserves. Q_tot_res(MVR) represents the combination of selecting the option to plot The total reactive injection at the bus... and including reserves.
Note: The reserves and the existing injection in the above plot are represented solely by switched shunts. All of the curves tend to converge toward the same Q at lower voltages. This is because of the relationship of the actual output of a switched shunt to the nominal output: (Actual Mvar) = (Nominal Mvar)*V2.