Efficient modeling of cascaded-multilevel static synchronous compensator on electronicmagnetic transient simulation program

Cascaded-Multilevel STATCOM (CM-STATCOM) is of great development potential in reactive power compensation device. But it consists of large number of semiconductor devices which significant increases the simulation time in electromagnetic transient simulation program. This paper proposes an efficient model of CM-STATCOM based on Dommel algorithm, which replaces the arm circuit with Thevenin equivalent circuit and numerical calculation block. This paper also introduces ideal switching devices to reduce computation quantity in calculation block. The proposed model that preserves the individual identity of H-bridge and interface to control system is of wide applicability and high accuracy. Besides, the size of nodal admittance matrix is reduced by several orders of magnitude so that the simulation time is reduced drastically. The proposed model is validated in PSCAD/EMTDC under different condition by comparisons with traditional model.