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Low-frequency switching strategies are considered as an effective way of achieving efficient performance in multilevel inverters. Selective harmonic elimination (SHE) is a modulation technique of this category which gives a superior outcome suppressing low-order detrimental harmonics. Limited number of decision variables offered by SHE in the corresponding non-linear equations hinders obtaining high-quality waveforms. Current research is targeted on two distinct objectives for cascaded H-bridge inverters. First objective is to obtain a high-quality output signal. The second one is accomplishing a realistic solution with compromised voltage quality where a broad operating range becomes mathematically challenging. These aims are achievable by deploying additional degree of freedom in the equation set. In other words, the introduction of floating voltage levels contributes to effectively doubling the number of variables. The enhancement of output waveforms is presented through several illustrations and comparisons. Subsequent laboratory implementation validates the proposal and confirms its feasibility.

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This paper presents an optimal cooperative voltage control approach, which coordinates storage units in a distribution network. This technique is developed for storage systems' active power management with a local strategy to provide robust voltage control and a distributed strategy to deliver optimal storage utilization. Accordingly, three control criteria based on predefined node voltage limits are used for network operation including normal, over-voltage, and under-voltage control modes. The contribution of storage units for voltage support is determined using the control modes and the coordination strategies proposed in this paper. This technique is evaluated in two case studies to assess its capability.