EMT Ph3 Averaged VSI Implementation

How the EMT averaged inverter is arranged in code and interfaced to the solver.

The equations are derived under EMT Ph3 averaged voltage source inverter. This page covers only their arrangement in code.

Class and base

EMT::Ph3::AvVoltSourceInverterStateSpace is final and derives from EMT::Ph3::TwoTerminalVTypeVariableSSNComp. Unlike the dynamic phasor ports of this model, every state here is real, so it uses the plain variable state-space nodal base rather than the mixed one. The base sets PhaseType::ABC in its constructor, which this component relies on.

State layout

Fourteen real states, controls first and filter states afterwards.

IndexNameKind
0ThetaPLLPLL angle
1PhiPLLPLL integrator
2, 3PFiltered, QFilteredpower filter
4, 5PhiD, PhiQouter power control integrators
6, 7GammaD, GammaQinner current control integrators
8–10VcA, VcB, VcCfilter capacitor voltage, per phase
11–13IfA, IfB, IfCfilter inductor current, per phase

The first state is the raw PLL angle. The dynamic phasor ports track the deviation from the nominal carrier phase instead, because there the angle is compared against a carrier and an unboundedly growing value costs relinearization accuracy. In EMT there is no carrier to drift against, so the raw angle is used directly.

Six real filter states here correspond to two complex envelopes in the single-phase dynamic phasor model and six in the three-phase one. That correspondence is the practical statement of what the envelope transform buys.

Source and examples