Extended Ward

See also

Unit Systems and Conventions

Create Function

pandapower.create.create_xward(net, bus, ps_mw, qs_mvar, pz_mw, qz_mvar, r_ohm, x_ohm, vm_pu, in_service=get_default_value('xward', 'in_service'), name=None, index=None, slack_weight=get_default_value('xward', 'slack_weight'), **kwargs)

Creates an extended ward equivalent.

A ward equivalent is a combination of an impedance load, a PQ load and as voltage source with an internal impedance.

Parameters::

net: The pandapower net within the impedance should be created bus: bus of the ward equivalent ps_mw: active power of the PQ load qs_mvar: reactive power of the PQ load pz_mw: active power of the impedance load in MW at 1.pu voltage qz_mvar: reactive power of the impedance load in MVar at 1.pu voltage r_ohm: internal resistance of the voltage source x_ohm: internal reactance of the voltage source vm_pu: voltage magnitude at the additional PV-node slack_weight: Contribution factor for distributed slack power flow calculation (active power balancing)

Returns:

the id of the created xward

Parameters:

• net (pandapowerNet)

• bus (int | integer)

• ps_mw (float)

• qs_mvar (float)

• pz_mw (float)

• qz_mvar (float)

• r_ohm (float)

• x_ohm (float)

• vm_pu (float)

• in_service (bool)

• name (str | None)

• index (int | integer | None)

• slack_weight (float)

Table Structure

net.xward

Parameter	Datatype	Value Range	Explanation	nullable	required
name			name of the extended ward equivalent	✓
bus	int	>=0	index of connected bus		✓
ps_mw	float		constant active power demand [MW]		✓
qs_mvar	float		constant reactive power demand [MVar]		✓
pz_mw	float		constant impedance active power demand at 1.0 pu [MW]		✓
qz_mvar	float		constant impedance reactive power demand at 1.0 pu [MVar]		✓
r_ohm	float	>0	internal resistance of the voltage source [ohm]		✓
x_ohm	float	>0	internal reactance of the voltage source [ohm]		✓
vm_pu	float	>0	voltage source set point [p.u]		✓
slack_weight	float		Contribution factor for distributed slack power	✓
in_service	bool		specifies if the extended ward equivalent is in service.		✓

Electric Model

The extended ward equivalent is a ward equivalent: with additional PV-node with an internal resistance.

The constant apparent power is given by:

\begin{align*} P_{const} &= ps\_mw\\ Q_{const} &= qs\_mvar\\ \end{align*}

The shunt admittance part of the extended ward equivalent is calculated as described here:

\begin{align*} \underline{y}_{shunt} &= \frac{pz\_mw + j \cdot qz\_mvar}{S_{N}} \end{align*}

The internal resistance is defined as:

\begin{align*} \underline{z}_{int} &= r\_pu + j \cdot x\_pu \end{align*}

The internal voltage source is modelled as a PV-node (generator) with:

\begin{align*} p\_mw &= 0 \\ vm\_pu &= vm\_pu \end{align*}

Result Table

net.res_xward

Parameter	Datatype	Explanation	nullable	required
p_mw	float	active power demand of the ward equivalent [MW]	✓	✓
q_mvar	float	reactive power demand of the ward equivalent [MVar]	✓	✓
vm_pu	float	voltage at the ward bus [p.u]	✓	✓
va_internal_degree	float		✓	✓
vm_internal_pu	float		✓	✓

\begin{align*} vm\_pu &= v_{bus} \\ p\_mw &= P_{const} + Re(\frac{\underline{V}_{bus}^2}{\underline{Y}_{shunt}}) + Re(\underline{I}_{int} \cdot \underline{V}_{bus}) \\ q_mvar &= Q_{const} + Im(\frac{\underline{V}_{bus}^2}{\underline{Y}_{shunt}} + Im(\underline{I}_{int} \cdot \underline{V}_{bus}) ) \end{align*}