Reduction of converter rating for a delta-connected STATCOM by optimizing phase harmonic references

Static synchronous compensator (STATCOM) with delta configuration has been widely applied to compensate reactive current, unbalance current and harmonics in a three-phase three-wire system. When the phase reference currents are calculated, there are infinite number of solutions with a given set of line currents for a delta-connected STATCOM. This paper proposes a phase harmonic reference currents calculation method. The proposed method is able to balance the harmonic currents among three clusters of the STATCOM without affecting the power quality conditioning. Therefore, the total rating of the three-phase STATCOM is reduced and the system initial cost is lower. Simulation results are provided to show the effectiveness of the proposed method. Results indicate that the maximum phase currents of the delta-connected STATCOM is reduced and unbalance, reactive and harmonic currents are compensated simultaneously.