Support structure arrangement for a modular converter, the support structure arrangement comprising: a plurality of support structures which are arranged in a row, wherein each support structure comprises: a holder for the insertion of at least one power electronics module; and a support frame which is composed of pipes (16, 22) which are connected to one another and form corners and edges of an electrically conductive outer geometry which surrounds the holder, wherein the corners and edges have a radius of curvature which is greater than a prespecified minimum radius, and wherein the outer geometry is designed to homogenize an electrical field strength on an outside of the support structure, and wherein the support frame comprises two rectangular pipe rings with rounded corners, which pipe rings are arranged parallel in relation to one another and are connected by means of pipes which run orthogonally in relation to the pipe rings, wherein each of the support structures further comprises: a plurality of insulators which are fitted to the outer geometry and are designed for the support structure to be able to be fastened to a surrounding structure or to a further support structure, wherein the support structure arrangement further comprises: a coolant pipe (70a, 70b), which is composed of insulating material, for providing cooling liquid for power electronics modules in the support structures (10a, 10b, 10c, 10d); and at least one electrode (74b, 74c), which is arranged in the coolant pipe (70a, 70b), within the outer geometry of a support structure (10a, 10b, 10c, 10d) which is connected to the support structure and/or can be electrically conductively connected to a power electronics module in the support structure in such a way that the electrode is at the potential of the support structure and/or of the power electronics module, wherein the coolant pipe (70a, 70b) is guided along the row within the outer geometries of the support structures (10a, 10b, 10c, 10d), and wherein the electrode is arranged in a first support structure in the row, and a further electrode is arranged in the last support structure of the row. a plurality of support structures which are arranged in a row, wherein each support structure comprises: a holder for the insertion of at least one power electronics module; and a support frame which is composed of pipes (16, 22) which are connected to one another and form corners and edges of an electrically conductive outer geometry which surrounds the holder, a holder for the insertion of at least one power electronics module; and a support frame which is composed of pipes (16, 22) which are connected to one another and form corners and edges of an electrically conductive outer geometry which surrounds the holder, wherein the corners and edges have a radius of curvature which is greater than a prespecified minimum radius, and wherein the outer geometry is designed to homogenize an electrical field strength on an outside of the support structure, and wherein the support frame comprises two rectangular pipe rings with rounded corners, which pipe rings are arranged parallel in relation to one another and are connected by means of pipes which run orthogonally in relation to the pipe rings, wherein each of the support structures further comprises: a plurality of insulators which are fitted to the outer geometry and are designed for the support structure to be able to be fastened to a surrounding structure or to a further support structure, wherein the support structure arrangement further comprises: a coolant pipe (70a, 70b), which is composed of insulating material, for providing cooling liquid for power electronics modules in the support structures (10a, 10b, 10c, 10d); and at least one electrode (74b, 74c), which is arranged in the coolant pipe (70a, 70b), within the outer geometry of a support structure (10a, 10b, 10c, 10d) which is connected to the support structure and/or can be electrically conductively connected to a power electronics module in the support structure in such a way that the electrode is at the potential of the support structure and/or of the power electronics module, a coolant pipe (70a, 70b), which is composed of insulating material, for providing cooling liquid for power electronics modules in the support structures (10a, 10b, 10c, 10d); and at least one electrode (74b, 74c), which is arranged in the coolant pipe (70a, 70b), within the outer geometry of a support structure (10a, 10b, 10c, 10d) which is connected to the support structure and/or can be electrically conductively connected to a power electronics module in the support structure in such a way that the electrode is at the potential of the support structure and/or of the power electronics module, wherein the coolant pipe (70a, 70b) is guided along the row within the outer geometries of the support structures (10a, 10b, 10c, 10d), and wherein the electrode is arranged in a first support structure in the row, and a further electrode is arranged in the last support structure of the row.