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The cascaded H-bridge (CHB) is a popular topology for Static Synchronous Compensator (STATCOM) applications. Since this converter is composed of tens/hundreds of components, concerns related to reliability are inherent in the design of this converter. Generally, redundant cells are used, increasing the cost of STATCOM. Indeed, there is a potential for fault-tolerant operation when the overmodulation region is considered. This work explores the inherent redundancy of the delta-CHB in the overmodulation region. Initially, an analytical expression for the boundary between the linear region and overmodulation is determined and validated for different operating conditions. Then, the fault-tolerant is evaluated in a simulation environment, considering a case study of a 17 MVA/13.8 kV delta-CHB STATCOM composed of 24 cells per arm. Symmetric and asymmetric failures are addressed. The results indicate that the converter is capable of operating at rated conditions after 4 faults distributed in the three converter arms (5.5 % redundancy factor) without exceeding the recommended harmonic distortion values.

Partial shading is a problem that affects solar systems not only in their efficiency, but also in its lifetime. As a solution, integrated converters enable mismatched modules to deliver their maximum power. Voltage Equalizers are a type of partial power processing integrated converters, which results in more efficiency. There are many types of voltage equalizers, divided in three different architectures and based in many topologies, i.e. buck-boost, flyback, switched capacitors and voltage multipliers. Thus, in this paper, a comparative analysis of these converters are made, considering reliability and working principle, which is explained through simulation results. At the conclusions are made, pointing which circuit may be the best choice for a voltage equalizer.

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