Extended Ward

See also

Unit Systems and Conventions

Create Function

pandapower.create_xward(net, bus, ps_kw, qs_kvar, pz_kw, qz_kvar, r_ohm, x_ohm, vm_pu, in_service=True, name=None, index=None)

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.

INPUT:

net - The pandapower net within the impedance should be created

bus (int) - bus of the ward equivalent

ps_kw (float) - active power of the PQ load

qs_kvar (float) - reactive power of the PQ load

pz_kw (float) - active power of the impedance load in kW at 1.pu voltage

qz_kvar (float) - reactive power of the impedance load in kVar at 1.pu voltage

vm_pu (float)

OUTPUT:
xward id

Result Parameters

net.xward

Parameter Datatype Value Range Explanation
name string   name of the extended ward equivalent
bus* integer   index of connected bus
ps_kw* float   constant active power demand [kW]
qs_kvar* float   constant reactive power demand [kVar]
pz_kw* float   constant impedance active power demand at 1.0 pu [kW]
qz_kvar* float   constant impedance reactive power demand at 1.0 pu [kVar]
r_pu* float \(>\) 0 internal resistance of the voltage source [p.u]
x_pu* float \(>\) 0 internal reactance of the voltage source [p.u]
vm_pu* float \(>\) 0 voltage source set point [p.u]
in_service* boolean True / False specifies if the extended ward equivalent is in service.

*necessary for executing a power flow calculation.

Electric Model

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

../_images/xward.png

The constant apparent power is given by:

\begin{align*} P_{const} &= ps\_kw\\ Q_{const} &= qs\_kvar\\ \end{align*}

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

\begin{align*} \underline{y}_{shunt} &= \frac{pz\_kw + j \cdot qz\_kvar}{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\_kw &= 0 \\ vm\_pu &= vm\_pu \end{align*}

Result Parameters

net.res_xward

Parameter Datatype Explanation
p_kw float active power demand of the ward equivalent [kW]
q_kvar float reactive power demand of the ward equivalent [kVar]
vm_pu float voltage at the ward bus [p.u]
\begin{align*} vm\_pu &= v_{bus} \\ p\_kw &= P_{const} + Re(\frac{\underline{V}_{bus}^2}{\underline{Y}_{shunt}}) + Re(\underline{I}_{int} \cdot \underline{V}_{bus}) \\ q_kvar &= Q_{const} + Im(\frac{\underline{V}_{bus}^2}{\underline{Y}_{shunt}} + Im(\underline{I}_{int} \cdot \underline{V}_{bus}) ) \end{align*}