This paper focused on reviewing the main types of topologies and control strategies employed for the operation of multilevel inverter. Advantages and disadvantages of the topologies and the control techniques in relation to one another are equally reviewed. Recent proposed methods employed to improve the harmonic performance, reduce electromagnetic interference (EMI), lower stress on the power switches, eliminate DC link voltage imbalance and simplify the pulse width modulation control algorithms are fully reviewed. Selective harmonic elimination modulation technique is used in generating the 11-level of output voltage. It is aimed at reducing the total harmonic distortion as low as possible.

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Power system operation and control required models of generators, lines and loads to be accurately estimated, this is to enable operators make a reliable decision on the system.  Generators and lines models are so far considered accurate, while load models are considered perplexing due to invention of new types of loads, distribution system are transforming from passive to active. Future distribution systems are desired to be smart and for a network to be smart the system as to be fully and accurately represented. Penetration of renewable energy and application of power electronic devices as well as participation of active customers in distribution systems make traditional methods of load modeling absolute. Accurate load modeling is required to address the new challenges evolving in the task of power system operation, control and stability studies. It is also an interest of power system researchers globally to realize Smart Networks (SNs), in which accurate load models are required. This work described a review of techniques and approaches for load modeling from traditional methods to the state of art in the area. In addition, gaps in the literature as well as research directions are also pointed out.

In this paper, modeling and simulation of nonlinear, Half-car Active Vehicle Suspension System (HAVSS) reinforced with PID controller is presented. The model has 4 degrees of freedom; comprising of heave movements of the front and rear axle, pitch and heave motions of the unsprung mass of the vehicle. The vehicle is excited by a triangular bump on an otherwise smooth road. The objective of the presented model is to isolate the vehicle body from these road disturbances in order to maximize passenger ride comfort and retain continuous road-wheel contact. PID controller is used to supress the vibrations generated from the road unevenness. Newton's approach is used in system modeling due its simplicity over D'Alembert's and Lagrange's approach. The simulation, carried out in MATLAB environment, vividly shows the superior performance; in both effectiveness and robustness of the HAVSS over its passive control counterpart.