Closed Loop Control Using RSAPS Algorithm for 5-Level CHB Multilevel Inverter

This paper discusses the design and implementation of a Robust Shrine Affine Projection Sign (RSAPS) adaptive control algorithm for power quality improvement. Various limitations of conventional 2-level inverters can be overcome using a 5-level Cascaded H-Bridge multilevel inverter (CHB-MLI). Such a CHB-MLI is realized and controlled as a distribution static compensator (DSTATCOM) unit in this paper. The DC link of capacitors have been maintained to reference value by using proportional-integral (PI) controllers without using complex balancing circuits. Extensive simulation has been performed and a scaled -down experimental prototype model has been developed in the laboratory to test the system under steady state and dynamic load conditions using dSPACE-1104 digital signal processor. The simulation and experimental results show the source current harmonics, DC voltage regulation, power factor correction, weight updation etc. under varying load. The proposed algorithm gives satisfactory performance in terms of weight convergence, computational burden, mean square error (MSE) etc. under dynamic load conditions and in addition the THD obtained in source voltage and current is within acceptable IEEE-519 limits.