A grid forming vector current control system for controlling a grid intertie, the system comprising: a first terminal configured to be connected to a first power grid (A), the first terminal comprising a first current control unit , a first virtual admittance unit , and a first phase locked loop, PLL, unit , wherein the first virtual admittance unit and the first PLL unit are configured to emulate an inertia of a first virtual synchronous machine, VSM, and a first virtual current source is connected in parallel to the first VSM ; the grid forming vector current control system is characterised in further comprising : a second terminal configured to be connected to a second power grid (B), the second terminal comprising a second current control unit , a second virtual admittance unit , and a second PLL unit , wherein the second virtual admittance unit and the second PLL unit are configured to emulate an inertia of a second virtual synchronous machine, VSM, and a second virtual current source is connected in parallel to the second VSM ; and a controller being configured to use a transient power P VSM1 consumed by the first VSM to generate a power-equivalent current reference to control the second virtual current source and to use a transient power P VSM2 consumed by the second VSM to generate a power-equivalent current reference to control the first virtual current source . a first terminal configured to be connected to a first power grid (A), the first terminal comprising a first current control unit , a first virtual admittance unit , and a first phase locked loop, PLL, unit , wherein the first virtual admittance unit and the first PLL unit are configured to emulate an inertia of a first virtual synchronous machine, VSM, and a first virtual current source is connected in parallel to the first VSM ; the grid forming vector current control system is characterised in further comprising : a second terminal configured to be connected to a second power grid (B), the second terminal comprising a second current control unit , a second virtual admittance unit , and a second PLL unit , wherein the second virtual admittance unit and the second PLL unit are configured to emulate an inertia of a second virtual synchronous machine, VSM, and a second virtual current source is connected in parallel to the second VSM ; and a controller being configured to use a transient power P VSM1 consumed by the first VSM to generate a power-equivalent current reference to control the second virtual current source and to use a transient power P VSM2 consumed by the second VSM to generate a power-equivalent current reference to control the first virtual current source . a second terminal configured to be connected to a second power grid (B), the second terminal comprising a second current control unit , a second virtual admittance unit , and a second PLL unit , wherein the second virtual admittance unit and the second PLL unit are configured to emulate an inertia of a second virtual synchronous machine, VSM, and a second virtual current source is connected in parallel to the second VSM ; and a controller being configured to use a transient power P VSM1 consumed by the first VSM to generate a power-equivalent current reference to control the second virtual current source and to use a transient power P VSM2 consumed by the second VSM to generate a power-equivalent current reference to control the first virtual current source . <EOS>