Study on the compound cascaded STATCOM and compensating for 3-phase unbalancd loads

The existing 3-phase cascaded STATCOMs have two connection types, Y connection and Δ connection, which are very different from each other in the structure, functionality, reliability, economy and technical realization. Based on the deep comparative analysis of the merits and demerits of these two connection types, this paper puts forward a compound cascaded STATCOM. The internal relations and distinctions among the Y-connected and the Δ-connected and the compound cascaded STATCOM are revealed from two aspects, mathematical model and physical significance. The implementation method of compensating 3-phase unbalanced loads by the compound cascaded STATCOM is presented and the simulation results have proved the effectiveness and superiority of the new topology. Research results show that the compound cascaded STATCOM with comparative advantage in technology and economy has inherited the superiorities and overcame the shortcomings of the Y connection and Δ connection, which is worth popularizing in the field of high power and high voltage 3-phase unbalanced system.