Description

This PQ load is a two-terminal single-phase element consisting of equivalent RL series or RC series branch where each branch can have an equivalent resistance (P → R), an equivalent inductance (Q > 0 → L) or an equivalent capacitor (Q < 0 → C) connected in series. This block is intended to be connected between phases in a three-phase network.

Table of Contents

Mask and Parameters

General Parameters:

V0	Base value for PU conversion (kV)
F0	Base value for PU conversion (Hz)

Load Parameters:

Base active power (P0)	1-phase active power under nominal conditions (kW)
Base reactive power (Q0)	1-phase reactive power under nominal conditions (kW)
Np	Active power - Voltage variation coefficient
Nq	Reactive power - Voltage variation coefficient
Kpf	Active power - Frequency variation coefficient
Kqf	Reactive power - Frequency variation coefficient

Ports, Inputs, Outputs and Signals Available for Monitoring

Ports

Net_1: Network connection (supports only 1-phase connections)
Net_3: Network connection (supports only 1-phase connections)

Inputs

None

Outputs

None

Sensors

F: Estimated current at the point of connection
Lout: Effective inductance or Capacitance
Rout: Effective resistance
Vrms: Estimated RMS voltage at the point of connection

Description of the Load Model

Load Model

The PQ load consists of the series combination of equivalent R, L and C branches and the series combination of equivalent R and L branches. The following rules are applied:

If P=0 and Q=0, the element becomes disconnected in all solution methods.
The RL series inductance equivalent is calculated using:

The resistance value in the RL series combination is given by:

When Q<0, the capacitance value becomes:

Model Equations

The model equations of this load are given by:

where:

: Active power under nominal conditions

: Reactive power under nominal conditions

: Nominal voltage

: Frequency deviation from the nominal value F0 in pu.

: Active power-Frequency coefficient

: Reactive power-Frequency coefficient

: Active power-Voltage coefficient

: Reactive power-Voltage coefficient

: RMS voltage measured between connection nodes Net_T1 and Net_T3

By adjusting Np and Nq equal to 0, 1, or 2, the load can be set to work as a constant power, constant current, or constant impedance, respectively.

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