VSC DC Line Model: VHVDC1
Added support for this model in Version 21, build on November 20, 2020

Following corrections are applied when initializing this model in Transient Stability for the parameters Tr, Tp, Tq
- If 0.0 < T < 2*TimeStep then T = 0, ElseIf 2*TimeStep < T < 4*TimeStep then T = 4*TimeStep
TimeStep represents the integration time step being used as described on TimeStep
Model Equations and/or Block Diagrams