DC Line Options: Rectifier/Inverter Parameters

 

This page is found on the DC Transmission Line Options dialog. This page is used to enter parameters associated with both the rectifier and inverter end of the dc line.

 

The following parameters are available for both the rectifier and inverter:

 

# of Bridges

Number of valve bridges in series.

Base Voltage

Base AC voltage in kV on primary side of transformer.

XF Ratio

Transformer ratio.

XF Tap

Transformer tap setting.

XF Min/Max Tap, XF Tap Step

Transformer minimum and maximum tap settings, and the tap's step size.

Commuting XF Resistance and Reactance

Commuting resistance and reactance for the transformer, in ohms.

Minimum, Maximum, and Actual Firing Angle

Minimum, maximum, and actual values of the firing angle for the rectifier.

 

DC transmission line options relate the Power and Reactive Power injections created at DC converter terminals.

 

Fixed Parameters of the Converter

Nr and Ni = number of bridges at rectifier and inverter

Xcr and Xci = commutating reactance in Ohms per phase

Rcr and Rci = commutating resistance in Ohms per phase (these model converter losses)

Vioder and Vdiodei = diode voltage drop at the rectifier and inverter (these model converter losses)

ACBaser and ACBasei= base AC voltage for the rectifier and inverter

TRr and TRi = ratio of DCBase/ACBase for the rectifier and inverter

Stepr and Stepi= step size for the variable AC tap at the converter

Limiting parameter of the converter

TapMin and TapMax = Minimum and maximum variable AC tap ratio

AlphaMin and AlphaMax or GammaMin and GammaMax= Minimum and maximum firing angle limits at converter

Imax = maximum dc current allowed through the converter

Variables calculated in the DC system

Vdcr, Vdci, Idcr, Idci = DC system voltage and current in kV and kAmps

Alpha and Gamma = firing angle at rectifier and inverter

Tap = Variable AC tap: (Note: TotalTap = FixedTap + Tap - 1.0)

Network Injection Equations for Rectifier and Inverters for the AC power flow solution

For a given terminal AC voltage in per unit, these equations convert the DC quantities into a real and reactive power demand at the terminal bus. The rectifier has positive values while the inverter has negative values.

A Power Flow Solution option exists to "Disable DC Line Transformer Tap Control". If that is chosen then the tap ratios for DC lines will remain fixed.

If tap control is allowed, then the DC taps will move between their minimum and maximum control range trying to keep the firing angle (Alpha or Gamma) and a minimum possible value that is still above the minimum firing angle.