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As wind energy production increases, reliability and fault-tolerant operation capability of wind energy systems are becoming more important. Modern wind energy production systems use power electronic converters which are unfortunately proved to be one of their most fragile parts and responsible for most of the system downtime. Real-time fault monitoring, fault diagnosis and proper system reconfiguration in these converters are therefore mandatory for fault-tolerant operation of the converter and the whole system. In this paper, a comprehensive fault-tolerant power electronics interface for wind energy systems with doubly-fed induction generators is presented and validated. The same power production capability will be guaranteed. The proposed solution also includes a robust and very fast open-circuit switch fault diagnosis algorithm, which is not sensitive to the operation conditions and is therefore suitable for this application. Simulation, Hardware in the Loop validation and experimental tests are carried out to demonstrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

The increased penetration of photovoltaic (PV) systems in different applications with critical loads such as in medical applications, industrial control systems, and telecommunications has highlighted pressing needs to address reliability and service continuity. Recently, distributed maximum power point tracking architectures, based on dc–dc converters, are being used increasingly in PV systems. Nevertheless, dc–dc converters are one of the important failure sources in a PV system. Since the semiconductor switches are one of the most critical elements in these converters, a fast switch fault detection method (FDM) is a mandatory step to guarantee the service continuity of these systems. This paper proposes a very fast FDM based on the shape of the inductor current associated to fault-tolerant (FT) operation for boost converter used in PV systems. By implementing fault diagnosis and reconfiguration strategies on a single field-programmable gate array target, both types of switch failure (open- and short-circuit faults) can be detected, identified and handled in real time. The FDM uses the signal provided by the current sensor dedicated to the control of the system. Consequently, no additional sensor is required. The proposed FT topology is based on a redundant switch. The results of hardware-in-the-loop and experimental tests, which all confirm the excellent performances of the proposed approach, are presented and discussed. The obtained results show that a switch fault can be detected in less than one switching period, typically around 100 ms in medium power applications, by the proposed FDM. [ABSTRACT FROM PUBLISHER]

In this paper, an FPGA-based fault-tolerant back-to-back converter without redundancy is studied. Before fault occurrence, the fault-tolerant converter operates like a conventional back-to-back six-leg converter, and after the fault, it becomes a five-leg converter. Design, implementation, and experimental verification of an FPGA-based reconfigurable control strategy for this converter are discussed. This reconfigurable control strategy allows the continuous operation of the converter with minimum affection from a fault in one of the semiconductor switches. A very fast detection scheme is used to detect and locate the fault. Implementation of the fault detection and of the fully digital control schemes on a single FPGA is realized, based on a suited methodology for rapid prototyping. FPGA in loop and also experimental tests are carried out, and the results are presented. These results confirm the capability of the proposed reconfigurable control and fault-tolerant structure. [ABSTRACT FROM PUBLISHER]

Abstract: This paper deals with reconfigurable back-to-back converter topology and control orders in Wind Energy Conversion Systems (WECS). A typical WECS with Doubly Fed Induction Generator (DFIG) in balanced conditions is concerned. Based on the classical topology, a fault tolerant converter without any redundancy has been studied. The presented fault tolerant topology allows a “five-leg” structure with converters reconfiguration after switch failure detection. Furthermore, the control strategy for classical topology can no longer be applied after fault occurrence. Thus, a “five-leg” control strategy has also been proposed. The validation of the reconfigurable digital controller for the studied WECS with DFIG topology has been performed using a Hardware-in-the-Loop (HIL) reconfigurable platform including a Field Programmable Gate Array (FPGA) chip. HIL simulation results in both healthy and fault conditions have been presented to show simultaneously the viability of the studied converters topology and the reconfigurable control. [Copyright &y& Elsevier]

Fast fault detection and reconfiguration of power converters is necessary in electrical drives to prevent further damage and to make the continuity of service possible. On the other hand, component minimized converters may provide the benefits of higher reliability and less volume and cost. In this paper, a new fault-tolerant converter topology is studied. This converter has five legs before the fault occurrence, and after fault detection the converter continues to function with four legs. A very fast fault detection and reconfiguration scheme is presented and studied. Simulations and experimental tests are performed to evaluate the structure requirements, the digital reconfigurable controller, and fault detection scheme. For experimental tests, the control and the fault detection and reconfiguration schemes are implemented on a single field-programmable gate array (FPGA) chip. Experimental and simulation results show the effectiveness of the proposed fault-tolerant topology and its FPGA-based control. [ABSTRACT FROM PUBLISHER]

In this paper, an FPGA-controlled fault tolerant back-to-back converter for DFIG-based wind energy conversion application is studied. Before an open-circuit failure in one of the semiconductors, the fault tolerant converter operates as a conventional back-to-back six-leg one. After the fault occurrence in one of the switches, the converter will continue its operation with the remaining five healthy legs. Design, implementation, simulation and experimental verification of a reconfigurable control strategy for the fault tolerant six/five leg converter used in wind energy conversion are discussed. The proposed reconfigurable control strategy allows the uninterrupted operation of the converter with minimum affection from an open-circuit switch failure in one of the semiconductors. Software reconfiguration is also necessary in PWM signal generation unit, to assure that proper gate signals are calculated and generated based on the actual five-leg structure Simulations and experimental tests are carried out and the results are presented and compared. They all confirm the capability of the studied reconfigurable control and proposed fault tolerant architecture in ensuring the system's service continuity. [ABSTRACT FROM AUTHOR]

Numerous advantages offered by Photovoltaic (PV) generation systems coupled with the increasing power demands for clean energy put PV systems in the front of many research works. For stand-alone applications powered with PV systems, the reliability of the power conversion stage is essential to ensure the continuous supply of energy. Therefore, in the case of any failure occurring in the power conversion stage, it is mandatory to provide remedial actions to guarantee the service continuity of the produced electrical power. This paper analyses the service continuity of a two-stage buck/buck-boost converter with energy storage, driven with synchronous control. The initial two-stage converter is made fault-tolerant and robust to failures of its two switches by adding only one additional switch associated with two diodes. In this study, only open-circuit switch faults are considered. The proposed fault-tolerant circuit and the initial one have the same electrical behavior when synchronous control is used. The applied synchronous control in both healthy conditions and post-fault operation ensures the same functionalities without degrading the system’s performances. The proposed two-stage synchronously-controlled circuit is validated through simulation in the cases of open circuit faults on the two switches of the initial converter. The obtained results show the feasibility of the proposed functional redundancy and the continuity of operation at full power after switch fault diagnosis. [ABSTRACT FROM AUTHOR]