This study describes the application of a soft computing methodknown as differential evolution (DE) to implement the harmonics elimination pulse-width modulation (HEPWM) for a 15-level, multi-level voltage source inverter (MVSI). The main feature of this technique is the wide range of fundamental output voltage that can be achieved, while maintaining a very low total harmonics distortion (below 6%). The fundamental voltage can be controlled very precisely (very small step size) and the trajectories of the HEPWM angles are continuous over the whole range of modulation indexmaking it very suitable for utility and variable speed drives application. The study details the procedures to obtain the HEPWM angles trajectories, which include the formulation of objective functions, appropriate selection of the DE evolutionary parameters and stopping criterions. The viability of the proposed method is simulated using MATLAB/Simulink and verified by a three-phase, cascaded-type MVSI test rig. Experimentally, The HEPWM waveforms are implemented using the Altera field programmable gate array, whereas the 15-level MVSI is built using metal-oxide semiconductor field effect transistor H-bridge. Selected results are presented; the simulation and hardware results are found to be in very close agreement with the theoretical predictions.

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Battery energy storage system (BESS) is used in many practical applications including uninterruptible power supplies (UPS), portable devices, electrical vehicles and renewable energy systems. To utilize BESS effectively, an efficient control operation is required. Various controllers have been introduced in the open literature. However, they are not considered the best fit due to their limitations. This includes their incapability of handling high-power rating BESS, low noise immunity, short life cycle and limited number of input and output interfaces. In this paper, the programmable logic controller (PLC) is used to control and monitor a 158.8 kWh offline BESS for a typical Malaysian household. TIA Portal V13 software by siemens is used to program the proposed PLC control. Human machine interface(HMI) system is used to monitor and simulate the control performance. The results show that the PLC approach provides an efficient and reliable control of the BESS in which a compact protection against the battery overcharging, under-discharging and overheating is achieved.

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