This paper proposes a dual two-level voltage-source inverter (DTL VSI) and its control to effectively integrate two dc sources into the multi-infeed ac/dc (MIACDC) power architecture of fully integrated power and energy systems (FIPESs). The current-controlled method is also synthesized and proposed to control the grid-connected DTL VSI. To this end, this article provides mathematical analyses comparing the DTL VSI with the conventional current-controlled grid-connected two-level VSIs (TL VSIs). The linearized state-space models of both systems are mathematically derived for analyzing the dynamics of both structures. These models reveal the salient feature of the proposed DTL VSIs used in grid integration. To this end, space-phasor analysis is employed, and the dynamics of the phase-locked loop (PLL) and the grid impedance are also considered. The proposed grid-connected DTL VSI (with the current-controlled algorithm) not only in weak grids (for normal grid conditions) but even after fault removal (for faulty grid conditions) stabilizes the active and reactive power dynamics with improved transient performance compared to that of its conventional counterpart. Therefore, it enhances the operation range of the VSIs integrating various entities in FIPES' MIACDC power architecture. This paper provides supportive simulation results and experiments generated by MATLAB and a scaled-down test rig, respectively.

In this paper, a near-state pulse-width modulation (NSPWM) algorithm is proposed and implemented on dual-twolevel voltage-source inverters (D2L-VSIs) in order to reduce the common-mode voltage (CMV), the inverter switching losses, the current total harmonic distortion, and the side effects of bearing currents-compared with space vector modulation (SVM) and PWM7. To gain these goals, two conventional two-level inverters of the D2L-VSI are controlled, separately, with specific switching sequences and an adjusted phase difference between the carriers of two inverters. For evaluating and comparing these PWM techniques mathematically, both CMV root mean square generated and switching losses of the D2L-VSI are formulated as a function of the power factor of the D2L-VSI, which is driven by the methods detailed in this study. Eventually, theories and analysis, as well as simulations and experimental results-which are generated by MATLAB/Simulink environment and a 300 W scaled-down D2LVSI prototype, respectively-authenticate the superiority of the proposed NSPWM over both SVM and PWM7.

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