Design With Operational Amplifiers And Analog Integrated Circuits

Thermo-sensitive electrical parameter (TSEP) approaches are widely employed in the junction temperature extraction and prediction of power semiconductor devices. In this paper, the turn-off delay time is explored as an indicator of a TSEP to extract the junction temperature from high-power insulated gate bipolar transistor (IGBT) modules. The parasitic inductor $L_{\rm eE}$ between the Kelvin and power emitter terminals of an IGBT module is utilized to extract the turn-off delay time. Furthermore, the monotonic dependence between the junction temperature and turn-off delay time is investigated. The beginning and end point of the turn-off delay time can be determined by monitoring the induced voltage $v_{\rm eE}$ across the inductor $L_{\rm eE}$ . A dynamic switching characteristic test platform for high-power IGBT modules is used to experimentally verify the theoretical analysis. The experimental results show that the dependency between IGBT junction temperature and turn-off delay time is near linear. It is established that the turn-off delay time is a viable TSEP with good linearity, fixed sensitivity, and offers nondestruction on-line IGBT junction temperature extraction.

Junction Temperature Extraction Approach With Turn-Off Delay Time for High-Voltage High-Power IGBT Modules

To ensure the power system operates safely and reliably, it is essential to monitor and evaluate the health condition of power equipment on-line or off-line. This study reviews the research status in condition monitoring and diagnosis of power equipment, including transformer, gas insulated switchgear, cable, external insulation, generator, and power capacitor in recent years. Although much progress has been made in technologies of condition monitoring and fault diagnosis such as test accuracy, fast and accurate fault localisation and recognition of fault types, there are still many deficiencies which needs further research work, including the reliability of signal collection from sensors, the accuracy of data treatment and analysis, anti-interference performance of test equipment, appropriate models used for condition evaluation. The prospective of condition monitoring and diagnosis technologies of power equipment are also presented in this study. It is proposed that the application of big data, internet of things and cloud computing should be expected and given special attention in the near future.

Condition monitoring and diagnosis of power equipment: review and prospective

With the increasing age of the primary equipment of the electrical grids there exists also an increasing need to know its internal condition. For this purpose, off- and online diagnostic methods and systems for power transformers have been developed in recent years. Online monitoring is used continuously during operation and offers possibilities to record the relevant stresses which can affect the lifetime. The evaluation of these data offers the possibility of detecting oncoming faults early. In comparison to this, offline methods require disconnecting the transformer from the electrical grid and are used during planned inspections or when the transformer is already failure suspicious. This contribution presents the status and current trends of different diagnostic techniques of power transformers. It provides significant tutorial elements, backed up by case studies, results and some analysis. The broadness and improvements of the presented diagnostic techniques show that the power transformer is not anymore a black box that does not allow a view into its internal condition. Reliable and accurate condition assessment is possible leading to more efficient maintenance strategies.

Diagnostic Measurements for Power Transformers

We present a robust, temperature and vibration insensitive fiber-optic current sensor. The sensor has been integrated into a high-voltage circuit breaker. One year field experience has been gained in two substations of the Italian railways.

Temperature and vibration insensitive fiber-optic current sensor

The Rogowski coil is an old device for current measurement. It has been modified and improved over a century and is still being studied for new applications. The Rogowski coil has various advantages over conventional magnetic current transformers (CTs). Not only can it be used instead of CT, but also it has various utilizations in other fields. This paper provides a brief review on different aspects of the Rogowski coil and its advancement procedure, during last decades. In this paper, the history of the coil is brifely reviewed and its bases and applications are discussed. The Rogowski coil is analyzed from different points of view, including different integration techniques in the output stage, models for the Rogowski coil, experimental methods for parameter measurement in models, and method for determining the damping resistor. Finally, a brief review over different applications of the coil ends this paper.

The Rogowski Coil Principles and Applications: A Review

FRA interpretation using numerical indices: State-of-the-art

This paper reviews the main features of acoustic emission technique. First, the characteristics of acoustic signals and their physics are addressed. Then, the structure of acoustic sensors employed for capturing signals is studied. In the next step, the acoustic method of PD measurement is compared with the standard electrical method. Afterward, the applications of AET in PD measurement in different equipment are summarized. All acoustic method and combined acoustic-electrical method for PD localization in transformers are discussed. Moreover, the applications of AET in the monitoring of GIS systems are explained, along with the acoustic behaviors of moving particles in these systems. Finally, the general considerations in the signal processing of the acoustic signals are reviewed.

Applications of the Acoustic Method in Partial Discharge Measurement: A Review

This study is an effort to evaluate the numerical indices for the assessment of frequency response analysis (FRA) to provide a deeper understanding of their characteristics First, the study introduces the indices in the literature and categorises them into three groups Then, the results of 11 case studies from an experimental setup, two transformer models, and a power transformer real case are employed to examine the indices from the monotonicity aspect Moreover, a short review on the interpretation experiences with indices is reported for further understanding This contribution continues with a novel uncertainty analysis on the measurement setup and, finally, evaluates the indices based on their vulnerability to these uncertainties Although the results show the advantage of some indices over the others in the FRA interpretation, further studies, especially with large transformers in the field, are needed to reach a general conclusion

Mohammad Hamed Samimi

Papers

The Rogowski Coil Principles and Applications: A Review

Diagnostic Measurements for Power Transformers

FRA interpretation using numerical indices: State-of-the-art

Applications of the Acoustic Method in Partial Discharge Measurement: A Review

Evaluation of numerical indices for the assessment of transformer frequency response