Three-phase passive (or uncontrolled) rectifiers are typically placed at the front end of the overall power conditioning circuit for AC to DC conversion in low-cost, small-scale renewable-energy systems, e.g. residential purposes wind turbines. Whenever a diode in one leg or multiple legs becomes faulty, offering an open circuit to the flow of current in both directions, it severely affects the power quality at the grid-side and may lead to the permanent disconnection of the power contributing unit from the grid. Even under a normal voltage rectification mode, an unbalance fault on the generator side may cause similar behaviour. To address these issues, this study presents a novel spectral analysis based fault detection and diagnosis (FDD) method for unbalance and open-circuited faults in the 3-phase uncontrolled rectifier. The proposed FDD algorithm accurately identifies the fault location based on magnitude and phase angles of different harmonic components of the filtered rectified voltage and specifically devised thresholds. The effectiveness of the proposed FDD algorithm is demonstrated through exhaustive MATLAB simulations of the grid-connected power conditioning unit with variable 3-phase supply. Subsequently, the hardware implementation of the overall experiment is demonstrated under a fixed voltage, and a fixed frequency source fed 3-phase uncontrolled rectifier.

中文翻译：

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基于频谱分析的可再生能源系统三相无源整流器故障诊断算法

三相无源（或不受控制）整流器通常放置在整个功率调节电路的前端，用于在低成本，小型可再生能源系统（例如住宅用风力涡轮机）中进行AC到DC转换。每当一个分支或多个分支中的二极管出现故障，使电流在两个方向上断路时，都会严重影响电网侧的电能质量，并可能导致供电单元与电网永久断开。格。即使在正常的电压整流模式下，发电机侧的不平衡故障也可能导致类似的行为。为了解决这些问题，本研究提出了一种新颖的基于频谱分析的故障检测和诊断（FDD）方法，用于三相不受控整流器中的不平衡和开路故障。已过滤整流电压和专门设计的阈值。通过对可变三相电源的并网功率调节单元进行详尽的MATLAB仿真，证明了所提出的FDD算法的有效性。随后，在固定电压和固定频率源馈电的三相非受控整流器下演示了整个实验的硬件实现。