This component models the load characteristics as a function of voltage magnitude and frequency, where the load real and reactive power our considered separately using the well known expressions:
And,
Where,
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Equivalent load real power |
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Rated real power per phase |
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Load voltage |
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Rated load voltage (RMS, L-G) |
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dP/dV Voltage index for real power |
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dP/dF Frequency index for real power |
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Equivalent load reactive power |
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Rated reactive power (+inductive) per phase |
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dQ/dV Voltage index for reactive power |
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dQ/dF Frequency index for reactive power |
NOTE: dQ, dP, dV and dF are in all per-unit quantities
Every half cycle (at the appropriate voltage zero), the shunt resistor is updated to reflect the non-linear load effect as a function of RMS voltage and frequency. Similarly, the shunt inductor or capacitor, in parallel to the load resistor, is updated every half cycle (at its voltage zero) to reflect its non-linear characteristic.
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Quick Reference for Index Parameter Selection |
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dP/dV |
dQ/dV |
dP/dF |
dQ/dF |
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| Constant Resistance |
2 |
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0 |
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| Constant Reactance |
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2 |
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0 |
| Constant Inductance |
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2 |
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-1 |
| Constant Capacitance |
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2 |
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1 |
| Constant Real Current |
1 |
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0 |
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| Constant Reactive Current |
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1 |
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0 |
| Constant Real Power |
0 |
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0 |
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| Constant Reactive Power |
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0 |
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0 |
IMPORTANT NOTE: The initial values of R, L and C are computed based on the rated conditions supplied by the user. These values are kept constant until 10 cycles of the fundamental frequency has passed.
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More: |
Fixed Load (1 and 3-Phase, LG) See Reference [3] for more details on static load models and typical values for NP, NQ, KPF and KQF. |
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Name for Identification |
Text |
Optional text parameter for identification of the component. |
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Rated Real Power |
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REAL |
Constant |
Real steady-state 1-phase power through load [MW] |
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Rated Reactive Power (+inductive) |
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REAL |
Constant |
Steady state reactive power through load, where inductive load is entered as +ve in value (capacitive as -ve) [MVAr] |
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Rated Load Voltage (RMS) |
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REAL |
Constant |
Expected steady state RMS volts across the load [kV] |
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Initial Terminal Voltage |
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REAL |
Constant |
Expected steady state RMS volts across the load [kV] |
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PQ Defined At |
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Choice |
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Select Rated Voltage or Initial Terminal Voltage. |
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Number of Parts in the Composite Load |
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Choice |
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Select 1, 2 or 3. |
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Fundamental Frequency |
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REAL |
Constant |
System fundamental frequency [Hz] |
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Scaling Factor |
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REAL |
Variable |
Enter a scaling factor for the load. Scaling factor should be positive. |
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Number of Cycles Before Load Release |
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REAL |
Constant |
Enter the number of cycles of the rated frequency during which time load is held constant. |
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Freq Index for Power (dP/dF) |
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REAL |
Constant |
Frequency index for real power |
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Freq Index for Q (dQ/dF) |
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REAL |
Constant |
Frequency index for reactive power |
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Volt Index for Power (dP/dV) |
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REAL |
Constant |
Voltage index for real power |
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Volt Index for Q (dQ/dV) |
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REAL |
Constant |
Voltage index for reactive power |
Internal OutputsInternal Outputs
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Effective Resistance |
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Text |
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Name for effective per phase resistance [W] |
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Effective Inductance |
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Text |
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Name for effective per phase inductance [H] |
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Effective Capacitance |
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Text |
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Name for effective per phase capacitance [mF] |
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Name for Branch Current |
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Text |
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Name for for branch current [kA] |
