Arrangement and a method for balancing power in an AC power transmission system

A method of controlling an arrangement which is connected to an alternating current (AC) power transmission system, the arrangement comprising a static synchronous compensator device having a converter unit and an energy storage unit connected with the converter unit, and a power absorption device, the method comprising:

• controlling the static synchronous compensator device to exchange power with the AC power transmission system, and
• controlling the power absorption device in dependence of a state of charge of the energy storage unit and a state of the power transmission system, including determining whether or not there is a need to absorb active power from the AC power transmission system in excess of what the static synchronous compensator device is currently absorbing, and
• when determining that there is the need, controlling the power absorption device to dissipate active power,
• wherein the power absorption device includes a resistor unit and a current control unit connected in series with the resistor unit;
• and
• wherein the arrangement further includes a control device connected with the static synchronous compensator device and with the power absorption device, said controlling the power absorption device to dissipate active power comprising controlling, by means of the control device, the current control unit to provide a current to the resistor unit.