CONTROL DEVICE FOR GRID-FORMING CONTROL, POWER SUPPORTING SYSTEM, AND METHOD

The present disclosure relates to a control device (20) configured for grid-forming control using a voltage source converter, VSC, (10) electrically connected to a power grid (40) via a point-of-common-coupling, PCC, the control device (20) comprising: a decoupling controller (21) configured to determine a VSC virtual electromotive force (vEMF) of said VSC (10) based at least on a first complex signal (K; γ, δ), which first complex signal (K; γ, δ) is based at least on a complex power (Sg; Pg, Qg) being exchanged between said VSC (10) and the power grid (40), and a complex power reference (Sref, Pref, Qref) for said complex power (Sg; Pg, Qg), and a current controller (22) configured to determine a VSC voltage reference (vc,ref) for said VSC (10) based at least on a grid voltage (vg) for said power grid (40) at said PCC, and a current reference (if,ref) for a current (if) propagating between said VSC (10) and said PCC, a virtual admittance unit (24) configured to determine said current reference (if,ref) based at least on a voltage input (vin) multiplied with a virtual admittance (Yv), wherein said voltage input (vin) is based at least on a voltage difference between said VSC virtual electromotive force (vEMF) and said grid voltage (vg), and said virtual admittance (Yv) is based at least on a virtual impedance between the VSC virtual electromotive force (vEMF) and said PCC, wherein the control device (20) is configured to provide said VSC voltage reference (vc,ref) to said VSC (10), and wherein said decoupling controller (21) comprises a phase compensation unit (211) configured to apply a phase compensation to said first complex signal (K; γ, δ), which phase compensation is selected to compensate for a phase-shift introduced by said virtual impedance. A method of grid-forming control and a power supporting system is also disclosed.