(b)Fig. 10. RMS value (a) Source voltage (b) load voltage
During VCM operation DSTATCOM no longer compensates for current related
PQ problems as observed in fig. 11(b) from 0.2 to 0.45seconds. Now, when
the unbalance in the system vanishes, the DSTATCOM again switches back
to CCM operation and further tries compensate current related PQ
problems.
5. CONCLUSION
In this paper, using hysteresis current control strategy, operation of
DSTATCOM is carried out to maintain source current sinusoidal and in
phase with the source voltage (CCM). Moreover a novel concept of single
phase SRF theory is used to mitigate voltage unbalance in a three phase
four wire system and so to maintain load voltage at 1 p.u. (VCM).
Further, a novel concept of Dual Functional DSTATCOM is proposed so that
single DSTATCOM can be utilized to mitigate both current and voltage
related PQ problems by switching of DSTATCOM between Current Controlled
Mode (CCM) and Voltage Controlled Mode (VCM). The simulation is
performed under MATLAB/Simulink environment and results show the
effectiveness of the proposed algorithm.