Comparison of voltage support services by means of STATCOM and smart transformer in medium voltage grid

Due to the increasing demand of electrical energy, especially in urban areas, the traditional distribution power grid reaches its limitations of operation (e.g. large current flow or voltage deviation). The distribution grid needs to be upgraded to ensure stability margin of operation. Since the cost of space is expensive and there is also resistance against installation of extra equipment from local resident, to install new equipment in distribution grid becomes difficult. The choice of new device to support the grid must consider not only the services but also the cost of equipment and space. The devices based on power electronics (STATCOM, smart transformer (ST)) are able to provide ancillary services such as voltage support to medium voltage (MV) distribution grid. In this paper, the ST is analyzed and compared with the STATCOM in terms of cost and performance. By means of literature review and simulation, the performance of ST has been analyzed. The result shows that the ST provides more services to assist the control in distribution grid than STATCOM. In order to achieve the same performance of voltage support, the investment of ST is less.