Estratégia De Tolerância A Falhas Para Um Conversor Delta-Chb Statcom Na Região De Sobremodulacão

Abstract

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.

Delta-CHB Statcom with Reduced Capacitance Through Third Harmonic Injection

“…This project was carried out considering a cluster reactance of 0.17 pu, a capacitor voltage ripple of 10%, and a dc-link voltage for the converter to operate in the limit between the linear region and the overmodulation. In addition, this project employs 1.7 kV IGBTs, following the guidelines proposed in [21]- [23]. The control strategy adopted is the same adopted in reference [20], which is a common control strategy for Delta-CHB converters.…”