- Oddbjørn Gjerde
- WP2 Lead
- SINTEF Energi AS
Reduced-Order Model of Distributed Generators with Internal Loops and Virtual Impedance
Challenge and objective
- Reduced-order converter models are useful in microgrid applications for being less computationally expensive and simpler to analyse.
- Models already used, only include basic control loops (ignores virtual impedance and internal control loops).
- The frequency range validity of these models has neither been thoroughly studied.
- A low-order model of a droop-controlled converter that includes internal control loops and virtual impedances is derived.
- The validity of the assumptions used to reduce the model is analysed and a criterion for deciding the frequency range in which the model can be used is proposed.
- The model shows that the DG internal control loops tends to reduce the stability margins.
- It is also shown that including quasi-stationary virtual impedances increases the stability margins.
- While the transient part of the virtual impedance, reduces the stability margins.
Impact for distribution system innovation
- The inclusion of critical control designs will preserve a simple model but improve the accuracy.
Reference in CINELDI
- F. Göthner, J. Roldán-Pérez, R. E. Torres-Olguin, O.M. Midtgård: "Reduced-Order Model of Distributed Generators With Internal Loops and Virtual Impedance", in IEEE Transactions on Smart Grid, 2022.