Back2Back Voltage Source Converter (B2B VSC)

The B2B VSC is implemented as the name suggests by using two VSC, which are connected on the AC side.

See also

Voltage Source Converter (VSC)

The Back2Back Voltage Source Converter (VSC), is a power electronic device used to convert alternating current (AC) to direct current (DC) and vice versa. It connects an AC system to a dual DC system. Normally it is used to create multi terminal HVDC systems. For example for modelling wind park interconnects with a metallic return line. Currently this construct is not possible, due to a limitation in the underlying pypower modelling approach. Otherwise this model employs two VSC which are connected to a single AC bus. In pandapower the VSC model include a coupling transformer, therefore the input parameter are split to both VSC, so each have: r_ohm/2, x_ohm/2 and r_dc_ohm/2.

See also

Unit Systems and Conventions

Create Function

pandapower.create.create_b2b_vsc(net, bus, bus_dc_plus, bus_dc_minus, r_ohm, x_ohm, r_dc_ohm, pl_dc_mw=0.0, control_mode_ac='vm_pu', control_value_ac=1.0, control_mode_dc='p_mw', control_value_dc=0.0, name=None, controllable=True, in_service=True, index=None, **kwargs)

Creates an VSC converter element - a shunt element with adjustable VSC internal voltage used to connect the AC grid and the DC grid. The element implements several control modes.

Does not work if connected to “PV” bus (gen bus, ext_grid bus)

Parameters:

  • **net** (pandapowerNet)

  • **bus** (int)

  • **bus_dc_plus** (int)

  • **bus_dc_minus** (int)

  • **r_ohm** (float)

  • **x_ohm** (float)

  • **r_dc_ohm** (float)

  • **pl_dc_mw** (float)

  • **control_mode_ac** (string)

  • **control_value_ac** (float)

  • **control_mode_dc** (string)

  • **control_value_dc** (float)

  • **name** (list of strs, None)

  • **controllable** (bool, True) – as a fixed voltage source connected via shunt impedance

  • **in_service** (bool, True)

  • **index** (int, None) – index one higher than the highest already existing index is selected.

  • net (pandapowerNet)

  • bus (int | integer)

  • bus_dc_plus (int | integer)

  • bus_dc_minus (int | integer)

  • r_ohm (float)

  • x_ohm (float)

  • r_dc_ohm (float)

  • pl_dc_mw (float)

  • control_mode_ac (str)

  • control_value_ac (float)

  • control_mode_dc (str)

  • control_value_dc (float)

  • name (str | None)

  • controllable (bool)

  • in_service (bool)

  • index (int | integer | None)

Returns:

index (int) - The unique ID of the created ssc

Return type:

int | integer

Input Parameters

net.b2b_vsc

Parameter

Datatype

Value Range

Explanation

name

string

name of the B2B VSC

bus*

integer

index of ac bus of the ac side of the B2B VSC

bus_dc_plus*

integer

index of dc bus of the plus dc side of the B2B VSC

bus_dc_minus*

integer

index of dc bus of the minus dc side of the B2B VSC

r_ohm*

float

\(\geq\) 0

resistance of the coupling transformer

x_ohm*

float

\(\geq\) 0

reactance of the coupling transformer

r_dc_ohm*

float

resistance of the internal dc resistance component of VSC

pl_dc_mw

float

no-load losses of the VSC on the DC side for the shunt R representing the no load losses

control_mode_ac*

string

“vm_pu”, “q_mvar”, “slack”

the control mode of the AC side of the B2B VSC

control_value_ac*

float

the value of the controlled parameter at the ac bus

control_mode_dc*

string

“vm_pu”, “p_mw”,

the control mode of the dc side of the B2B VSC

control_value_dc*

float

the value of the controlled parameter at the dc bus

controllable*

boolean

True / False

whether the element is considered as actively controlling

in_service*

boolean

True / False

specifies if the B2B VSC is in service.

*necessary for executing a power flow calculation.

Electric Model

Image was created with https://www.circuit2tikz.tf.fau.de/designer/. Back2Back Voltage Source Converters are self-commutated converters to connect HVAC and HVDC systems using devices suitable for high power electronic applications, such as IGBTs.

Limitations

Since the powerflow equations are modelled that every component is connected to the same ground, topologies employing a lifted or virtual ground are not currently supported. For example, one could attach two B2B VSC on the minus and plus side, and therefore “lift” one of the VSC to create a virtual ground for a metallic return line scenario. But in this case, the first lower VSC will be shorted by second upper VSC. Currently a workaround is employed by creating the topology, but setting the correspoinding metallic return line out of service. Then a specialized controller needs to be employed, which calculates the resulting currents and updates the out-of-service line. See test_facts_b2b_vsc.py: test_hvdc_interconnect_with_dmr() for an example.

Result Parameters

net.res_b2b_vsc

Parameter

Datatype

Explanation

p_mw

float

total active power consumption of B2B VSC [MW]

q_mvar

float

total reactive power consumption of B2B VSC [MVAr]

vm_internal_pu

float

voltage magnitude at vsc internal bus [pu]

va_internal_degree

float

voltage angle at vsc internal bus [degree]

vm_pu

float

voltage magnitude at B2B VSC ac bus [pu]

va_degree

float

voltage angle at B2B VSC ac bus [degree]

p_dc_mw_p

float

active power of the plus side of the B2B VSC [MW]

p_dc_mw_m

float

active power of the minus side of B2B VSC [MW]

vm_internal_dc_pu_p

float

voltage angle at the plus B2B VSC ac bus [pu]

vm_internal_dc_pu_m

float

voltage angle at the minus B2B VSC ac bus [pu]

vm_dc_pu_p

float

voltage magnitude at the plus B2B VSC ac bus [pu]

vm_dc_pu_m

float

voltage magnitude at the minus B2B VSC ac bus [pu]