Fixed Load

This component models the load characteristics as a function of voltage magnitude and frequency. The expression of the characteristics is as follows:

If this component is used in single-phase mode, every half cycle (at the appropriate voltage zero), the shunt resistor/inductor/capacitor is updated to reflect the nonlinear load effect as a function of RMS voltage and frequency.

If used in a 3-phase, single-line mode, the RLC values of all phases are changed when the voltage of any one of the phases goes through a zero crossing.

The load remains in constant impedance form until the user specified number of cycles of the fundamental frequency is passed. The nonlinear characteristic is effective within ±20% of the specified RMS voltage and ±DF% of the rated frequency (DF is defined as minimum of 10, 90/KPF and 90/KQF). Outside this range, the load reverts to constant impedance.

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 the specified number of cycles of the fundamental frequency has passed.

Input Parameters

Name	Text		Optional text parameter for identification of the component.

Rated Real Power per Phase	REAL	Constant	Real steady-state 1-phase power into load [MW].

Rated Reactive Power (+inductive) per Phase	REAL	Constant	Steady state reactive power into load, where inductive load is entered as +ve in value (capacitive as -ve) [MVAr].

Rated Load Voltage (RMS L-G)	REAL	Constant	Expected steady state line-to-ground RMS volts across the load [kV].

Initial Terminal Voltage	REAL	Constant	Initial terminal voltage [pu].

PQ Defined at	Choice		Select Rated Voltage or Initial Terminal Voltage.

Number of Parts in the Composite Load	Choice		Select 1, 2 or 3.

Fundamental Frequency	REAL	Constant	System fundamental frequency [Hz].

Scaling Factor	REAL	Variable	Enter a scaling factor for the load. Scaling factor should be positive.

Number of Cycles before Load Release	REAL	Constant	Enter the number of cycles of the rated frequency during which time load is held constant.

Display Details?	Choice		Select Yes or No. Selecting Yes will display Rated Real Power per Phase and Rated Reactive Power on the component graphic.

Frequency Index for P (dP/dF)	REAL	Constant	Frequency index for real power.

Frequency Index for Q (dQ/dF)	REAL	Constant	Frequency index for reactive power.

Voltage Index for P (dP/dV) - Part A	REAL	Constant	Voltage index for real power.

Voltage Index for Q (dQ/dV) - Part A	REAL	Constant	Voltage index for reactive power.

P =	Equivalent load real power
Q =	Equivalent load reactive power
Scale =	Load scaling factor
P0 =	Real power at specified condition (Rated or Initial terminal)
Q0 =	Reactive power at specified condition (Rated or Initial terminal)
	Load voltage
	Voltage at specified condition (Rated or Initial terminal)
KPF =	dP/dF Frequency index for real power
KQF =	dQ/dF Frequency index for reactive power
KA =	Portion of the load specified by the first term
NPA =	dP/dV voltage index for real power in the first term
NQA =	dQ/dV voltage index for reactive power in the first term
KB =	Portion of the load specified by the second term
NPB =	dP/dV voltage index for real power in the second term
NQB =	dQ/dV voltage index for reactive power in the second term
KC =	Portion of the load specified by the third term
NPC =	dP/dV voltage index for real power in the third term
NQC =	dQ/dV voltage index for reactive power in the third term

Effective Resistance per Phase	REAL	Output	Name for effective per phase resistance [W].

Effective Inductance per Phase	REAL	Output	Name for effective per phase inductance [H].

Effective Capacitance per Phase	REAL	Output	Name for effective per phase capacitance [mF].

Fixed Load (1 and 3-Phase, LG)

Description

Input Parameters