Method and arrangement to control an AC system

An arrangement to control an electrical property of a medium or high voltage AC system comprising a number n of phases with n being at least two, where the arrangement comprises

• a number n of phases, each phase comprising a series connection of at least two electrical elements with an intermediate connection point between each pair of the at least two electrical elements, where
• each of the n phases of the arrangement is connected on one side to an original common neutral point and on the other side to one of the n phases of the AC system,
• characterized in that the arrangement comprises
• a number [n−1] of first switchable interconnections, where the first switchable interconnections are each arranged between two intermediate connection points of two of the n phases of the arrangement, and
• at least one control unit arranged to control the first switchable interconnections to close, thereby interconnecting all n phases of the arrangement and thereby creating a new common neutral point consisting of the closed first switchable interconnections.