The Rogowski Coil Technology Advancements: A Review of High Current Applications

Rogowski coil (RC) also known as air-cored was suggested in 1912 and was introduced by German physician Walter Rogowski. This coil is developed for the measurement of alternating and transient high currents, it has the capability of measurement from a few milliamperes to more than 1MA. The advancement of technology and use of microprocessor-based modern signal processing devices have coursed improvement of the Rogowski coil and extended its applications in various places. This article will provide an overview of the theory of Rogowski coils and its high current applications. initially, the article discusses the principles and basics of high current Rogowski coils, explaining their design, construction, and operation. Besides, the research study explores the various high current applications of this coil. its uses overlap from laboratory testing to industrial equipment, Rogowski coils find Usefulness in fault detection, partial discharge measurement, and lightning current detection, surpassing traditional current sensing devices in aspects of speed, accuracy, and reliability. As a result, it is a valuable resource for academics, engineers, and practitioners looking to use this adaptive technology in a wide range of commercial and scientific activities.&nbsp

Development of non-conventional instrument transformers (NCIT) using smart materials

In this paper is presented a novel approach for current measurement using smart materials, magnetic shape memory (MSM) alloys. Their shape change can be controlled by the application of magnetic field or mechanical stress. This gives the possibility to measure currents by correlating the magnetic field produced by the current, shape change in an MSM- based sensor and the voltage output of a Linear Variable Differential Transducer (LVDT) actuated by this shape change. In the first part of the paper is presented a review of existing current measurement sensors by comparing their properties and highlighting their advantages and disadvantages

Modeling, Measurement and Mitigation of Fast Switching Issues in Voltage Source Inverters

Wide-bandgap devices are enjoying wider adoption across the power electronics industry for their superior properties and the resulting opportunities for higher efficiency and power density. However, various issues arise due to the faster switching speed, including switching transient voltage overshoot, unstable oscillation, gate driving and evaluation difficulty, measurement and monitoring challenge, and potential load insulation degradation. This dissertation first sets out to model and understand the switching transient voltage overshoots. Unique oscillation patterns and features of the turn-on and turn-off overvoltage are discovered and analyzed, which provides new insights into the switching transient. During the experimental characterization, a new unstable oscillation pattern is found during the trench MOSFET\u27s turn-off transient. The MOSFET channel may be falsely turned back on, resulting in severe oscillation and possible loss of control. Time-domain and large-signal analytical models are established, which reveals the negative impact of common-source inductances and unconventional capacitance curve of trench MOSFET. Besides the devices themselves, another determining part in their switching transient behavior is the gate driver. A programmable gate driver platform is proposed to readily adapt to different power semiconductors and driving schemes, which can greatly facilitate the evaluation and comparison of different devices and driving schemes. The faster switching speed of wide-bandgap devices also requires more demanding measurement and monitoring solutions. A novel combinational Rogowski coil concept is proposed, which leverages the self-integrating feature to further increase the bandwidth. Prototypes achieved more than 300 MHz bandwidth, while keeping the cross-sectional area less than 2.5 mm$^2$. Finally, the very high voltage slew rate of wide-bandgap devices may negatively impact the motor load insulation. Attempting to fully utilize the higher switching frequency capability, sinewave and $dv/dt$ filters are compared. It is shown that sinewave filters can achieve higher efficiency and power density than $dv/dt$ filters, especially for high frequency applications

Estudi de bobines Rogowski com a element sensor, per aplicacions de mesura i pel control de sistemes elèctrics

Aquest document presenta l’estudi de bobines Rogowski i les seves aplicacions com element de mesura. S’ha aprofundit en l’anàlisi de l’ample de banda i de la resistència de terminació a partir d’un conjunt de bobines Rogowski, construïdes dins de l’abast del projecte i dotades amb diferents formes i dimensions geomètriques i diferents paràmetres elèctrics. L’anàlisi està basat en les simulacions prèvies i els assajos experimentals duts a terme al laboratori. L’objectiu és concloure en la influència de les característiques de la bobina Rogowski en funció de la utilització que se li vulgui donar. S’exposa una explicació teòrica del funcionament de la bobina i del seu model d’estudi, el mètode de construcció i de caracterització dels diferents sensors estudiats i una observació de les aplicacions més comuns de la bobina Rogowski junt amb la realització d’assajos per a l’anàlisi del seu funcionament

Design and Implementation of Partial Discharge Measurement Sensors for On-line Condition Assessment of Power Distribution System Components

Unplanned interruptions of power supply due to failure of critical components of the distribution network have considerable impact on the modern society. Efficient condition assessment can avoid the loss of critical components by early detection of incoming threats. One of the biggest shortcomings of today's progressing maintenance technology is the lack of low cost instrumentation solutions which are simple in implementation and easily applicable to the network. In this work partial discharge (PD) measurements have been considered for insulation condition assessment of distribution system components such as overhead covered conductors (CCs) and cables. A high frequency Rogowski coil induction sensor is designed for this purpose. An accurate electrical model of the sensor is necessary for efficient signal processing of the sensed signal and for reliable interpretation of the measured signal. A new method to determine the electrical parameters of Rogowski coil sensor is presented. In-depth analysis of the design stages of Rogowski coil is presented using experimental and simulated environment. Various geometrical designs of Rogowski coil are investigated to analyze the effects of geometrical parameters on high frequency performance of the coil. The guidelines presented regarding geometrical structure are useful when trading off the benefits for better mechanical and electrical design of such sensors. Location of the detected PD faults is an important task of the diagnostics system in power lines. The conventional techniques of locating PD faults have been known for a single section of a power line. However, these techniques are not suitable for power lines having multi-sections or for branched line networks. In this work, finding the location of PD fault on a power line is recognized as a two stage function; (i) identification of the faulty section, and (ii) location of fault point on the identified section. The direction of arrival (DOA) technique is introduced to identify faulty section whereas fault point location can be determined by conventional techniques. The technique is equally applicable for CC lines or cable networks. The DOA technique is integrated over a cable feeder and an on-line automated condition monitoring and diagnostic scheme is proposed. Low cost, non-intrusive installation and favorable operating features of Rogowski coil sensor make it suitable for development of an enhanced and automated diagnostic system which can easily be integrated into the distribution network

Mathematical Modelling and Design of Current Sensors in Non-Conventional Instrument Transformers

This research brings a novel approach for current measurement using magnetic shape memory (MSM) smart alloys. The non-conventional instrument transformer (NCIT) proposed in this research uses the property of these alloys that their shape changes when exposed to a magnetic field. It has been shown that it is possible to measure alternating currents (a.c.) in high voltage overhead transmission lines by correlating the magnetic field produced by the current to shape changes in an MSM-based sensor. Methodologies for finite element modelling of the proposed NCIT have been developed. The developed methodology and obtained results are validated by comparing them to the results obtained through an experiment done by a manufacturer of MSM materials. 5M Ni-Mn-Ga MSM crystals with Type I twin boundaries and a load of 0.5 N/mm2 were identified as the most suitable type of MSM materials for this application. The combination of a very long fatigue life, with relatively low twinning stress, makes them the most prospective for use in MSM-based current sensors. The main characteristics of overhead transmission lines are described as well as the types of conductors typically used. This analysis brought us to the conclusion that special attention in this research should be given to ACSR and AAAC conductors, more specifically to 528-Al1/69- ST1A conductor (old code MOOSE) and 996-AL5 (old code REDWOOD). Additionally, the latest trends in the development of overhead transmission lines are discussed, as well as international standards which are relevant to these types of lines. These conductors were modelled in finite element (FE) package ANSYS APDL, together with the MSM element and the magnetic circuit, and included into a single finite element model. This approach allows us to take into account significant changes that take place within an MSM element during its elongation. Based on this, we were able to determine both the bottom and upper limits of the measurement range, optimise the NCIT for transmission lines, and propose several designs of the NCIT. Finally, this allowed relating the current inside the conductor to the voltage at the output of the LVDT

Advances in Sensors and Sensing for Technical Condition Assessment and NDT

The adequate assessment of key apparatus conditions is a hot topic in all branches of industry. Various online and offline diagnostic methods are widely applied to provide early detections of any abnormality in exploitation. Furthermore, different sensors may also be applied to capture selected physical quantities that may be used to indicate the type of potential fault. The essential steps of the signal analysis regarding the technical condition assessment process may be listed as: signal measurement (using relevant sensors), processing, modelling, and classification. In the Special Issue entitled “Advances in Sensors and Sensing for Technical Condition Assessment and NDT”, we present the latest research in various areas of technology