Incipient Current and Voltage Sensors Fault Diagnosis Scheme for Grid Side Converters

This paper proposes a model-based fault diagnosis scheme for incipient faults in the DC voltage and AC current sensors of the grid-tied converter, considering the coupling phenomena between the two sides of the converter that might cause fault propagation. First, a linear descriptor estimator is designed, based on a linear augmented descriptor model of a nonlinear grid side converter (GSC) system, while considering the effect of sensor noise and modeling uncertainty. Second, a time-varying estimator gain matrix for the design of the descriptor estimator is obtained by minimizing the sum of the variances of the estimation error. Lastly, the diagnosis of incipient sensor faults is designed using the derived analytical redundancy relations, based on the estimations provided by linear descriptor estimator. The results of this work are useful for the early diagnosis of incipient sensor faults, which can improve the safety and reliability of GSCs.