This component represents a standard IEEE-type Under Excitation Limiter (UEL) model. All input parameters are specified either in seconds (for time constants) or in per-unit/per-unit per second (for all other inputs). The external inputs and outputs are detailed below:
Inputs:
[VT/IT]: This input is a 3-element array and receives its data from the attached synchronous machine (provided that the machine is set to output this data). VT is the RMS terminal voltage. IT is the synchronous machine terminal current and is complex (i.e. has a real and imaginary component). The real component of IT is in phase with VT and the imaginary component of IT is in quadrature (lagging is positive) with VT.
VF: Represents the field voltage signal originating from an excitation system stabiliser, which is typically used for damping of oscillations.
VFB: Feedback voltage generated by the ST7C exciter model. This input is only available when the UEL2C model is used in combination with the ST7C model.
Outputs:
VUEL: This output represents the calculated Under Excitation Limiter (UEL) signal, which is typically used in conjunction with an exciter model.
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More: |
Under Excitation Limiter Model Under Excitation Limiter Transfer Functions PSCAD Reference [39] |
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Name for Identification |
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Optional text parameter for identification of the component. |
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UEL Type? |
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Choice |
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Select None, UEL1, or UEL2C as described in Under Excitation Limiter Transfer Functions. |
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Summation or Takeover? |
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Choice |
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Select either Summation or Takeover mode. |
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Exc. Sys. Stabilizer Output Available? |
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Choice |
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Select either Yes or No. |
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Is the Exciter ST7C? |
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Choice |
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Select either Yes or No. This option is available when UEL Type? | UEL1 or UEL2C is selected. |
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UEL Status: 0-Initialize;1-Release |
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INTEGER |
Variable |
A variable name can be used. This variable controls the status of the UEL component. This option is available when UEL Type? | UEL2C is selected. |
NOTE: This category is enabled only when UEL Type? | UEL1 is selected.
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UEL Excitation System Stabilizer Gain [KUF] |
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REAL |
Constant |
Enter a value for the UEL excitation system stabilizer gain [pu]. This value is available when Exc. Sys. Stabilizer Output Available? | Yes is selected. |
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UEL Radius Setting [KUR] |
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REAL |
Constant |
Enter a value for the UEL radius setting [pu]. |
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Upper Limit for y1 [VURmax] |
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REAL |
Constant |
Enter a value for the upper limit for y1 [pu]. |
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UEL Center Setting [KUC] |
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REAL |
Constant |
Enter a value for the UEL center setting [pu]. |
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Upper Limit for y2 [VUCmax] |
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REAL |
Constant |
Enter a value for the upper limit for y2 [pu]. |
UEL1 PI ControllerUEL1 PI Controller
NOTE: This category is enabled only when UEL Type? | UEL1 is selected.
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UEL Proportional Gain [KUL] |
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REAL |
Constant |
Enter a value for the UEL proportional gain [pu]. |
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UEL Integral Gain [KUI] |
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REAL |
Constant |
Enter a value for the UEL integral gain [pu/s]. |
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UEL PI Control Maximum Output [VUImax] |
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REAL |
Constant |
Enter a value for the UEL PI control maximum output [pu]. |
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UEL PI Control Minimum Output [VUImin] |
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REAL |
Constant |
Enter a value for the UEL PI control minimum output [pu]. |
UEL1 CompensatorsUEL1 Compensators
NOTE: This category is enabled only when UEL Type? | UEL1 is selected.
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UEL Numerator (Lead) Time Constant - 1st Block [TU1] |
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REAL |
Constant |
Enter a value for the UEL numerator (lead) time constant of the first lead/lag block [s]. |
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UEL Denominator (Lag) Time Constant - 1st Block [TU2] |
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REAL |
Constant |
Enter a value for the UEL denominator (lag) time constant of the first lead/lag block [s]. |
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UEL Numerator (Lead) Time Constant - 2nd Block [TU3] |
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REAL |
Constant |
Enter a value for the UEL numerator (lead) time constant of the second lead/lag block [s]. |
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UEL Denominator (Lag) Time Constant - 2nd Block [TU4] |
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REAL |
Constant |
Enter a value for the UEL denominator (lag) time constant of the second lead/lag block [s]. |
NOTE: This category is enabled only when UEL Type? | UEL1 is selected.
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UEL Maximum Output [VUELmax] |
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REAL |
Constant |
Enter a value for the UEL maximum output [pu]. |
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UEL Minimum Output [VUELmin] |
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REAL |
Constant |
Enter a value for the UEL minimum output [pu]. |
NOTE: This category is enabled only when UEL Type? | UEL2C is selected.
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UEL Excitation System Stabilizer Gain [KUF] |
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REAL |
Constant |
Enter a value for the UEL excitation system stabilizer gain [pu]. This value is available when Exc. Sys. Stabilizer Output Available? | Yes is selected. |
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UEL VFB Signal Filter Gain [KFB] |
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REAL |
Constant |
Enter a value for the UEL VFB signal filter gain [pu]. This value is available when Is the Exciter ST7C? | Yes is selected. |
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UEL VFB Signal Filter Time Constant [TUL] |
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REAL |
Constant |
Enter a value for the UEL VFB signal filter time constant [s]. This value is available when Is the Exciter ST7C? | Yes is selected. |
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UEL Real Power Filter Time Constant [TUP] |
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REAL |
Constant |
Enter a value for the UEL real power filter time constant [s]. |
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Voltage Exponent for Real Power Input to UEL Table [K1] |
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Choice |
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Select from 0, 1 or 2. |
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UEL Reactive Power Filter Time Constant [TUQ] |
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REAL |
Constant |
Enter a value for the UEL reactive power filter time constant [s]. |
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Voltage Exponent for Reactive Power Output of UEL Table [K2] |
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Choice |
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Select from 0, 1 or 2. |
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UEL Reactive Power Reference Time Constant [TQref] |
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REAL |
Constant |
Enter a value for the UEL reactive power reference time constant [s]. |
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UEL Voltage Filter Time Constant [TUV] |
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REAL |
Constant |
Enter a value for the UEL voltage filter time constant [s]. |
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UEL Voltage Bias [Vbias] |
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REAL |
Constant |
Enter a value for the UEL voltage bias [pu]. |
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UEL Logic Switch for Adjustable Gain [SW1] |
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Choice |
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Select from Pos. A (Fixed) or Pos. B (Adjustable). |
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UEL Fixed Gain Reduction Factor [Kfix] |
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REAL |
Constant |
Enter a value for the UEL fixed gain reduction factor [pu]. |
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Machine Q-axis Reactance [Xq] |
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REAL |
Constant |
Enter a value for the machine Q-axis reactance [pu]. This value is available when UEL Logic Switch for Adjustable Gain | Pos. B (Adjustable) is selected. |
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UEL Adjustable Gain Reduction Time Constant [Tadj] |
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REAL |
Constant |
Enter a value for the UEL adjustable gain reduction time constant [s]. This value is available when UEL Logic Switch for Adjustable Gain | Pos. B (Adjustable) is selected. |
UEL2C PI ControllerUEL2C PI Controller
NOTE: This category is enabled only when UEL Type? | UEL2C is selected.
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UEL Proportional Gain [KUL] |
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REAL |
Constant |
Enter a value for the UEL proportional gain [pu]. |
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UEL Integral Gain [KUI] |
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REAL |
Constant |
Enter a value for the UEL integral gain [pu/s]. |
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UEL PI Control Maximum Output [VUImax] |
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REAL |
Constant |
Enter a value for the UEL PI control maximum output [pu]. |
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UEL PI Control Minimum Output [VUImin] |
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REAL |
Constant |
Enter a value for the UEL PI control minimum output [pu]. |
UEL1 CompensatorsUEL1 Compensators
NOTE: This category is enabled only when UEL Type? | UEL2C is selected.
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UEL Numerator (Lead) Time Constant - 1st Block [TU1] |
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REAL |
Constant |
Enter a value for the UEL numerator (lead) time constant of the first lead/lag block [s]. |
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UEL Denominator (Lag) Time Constant - 1st Block [TU2] |
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REAL |
Constant |
Enter a value for the UEL denominator (lag) time constant of the first lead/lag block [s]. |
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UEL Maximum Output - 1st Block [VUELmax2] |
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REAL |
Constant |
Enter a value for the UEL maximum output of the first lead/lag block [pu]. |
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UEL Minimum Output - 1st Block [VUELmin2] |
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REAL |
Constant |
Enter a value for the UEL minimum output of the first lead/lag block [pu]. |
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UEL Numerator (Lead) Time Constant - 2nd Block [TU3] |
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REAL |
Constant |
Enter a value for the UEL numerator (lead) time constant of the second lead/lag block [s]. |
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UEL Denominator (Lag) Time Constant - 2nd Block [TU4] |
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REAL |
Constant |
Enter a value for the UEL denominator (lag) time constant of the second lead/lag block [s]. |
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UEL Maximum Output - 2nd Block [VUELmax1] |
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REAL |
Constant |
Enter a value for the UEL maximum output of the second lead/lag block [pu]. |
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UEL Minimum Output - 2nd Block [VUELmin1] |
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REAL |
Constant |
Enter a value for the UEL minimum output of the second lead/lag block [pu]. |
UEL2C Lookup TableUEL2C Lookup Table
NOTE: This category is enabled only when UEL Type? | UEL2C is selected.
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Number of Segments in Limiting Characteristics |
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Choice |
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Select from 1-6. |
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UEL Lookup Table Real Power - [P#] |
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REAL |
Constant |
Enter a value for the real power value corresponding to the specified point in the UEL lookup table [pu]. |
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UEL Lookup Table Reactive Power - [Q#] |
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REAL |
Constant |
Enter a value for the reactive power value corresponding to the specified point in the UEL lookup table [pu]. |