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This paper investigates the high-frequency transformer losses attributed to eddy currents in both conductors and the core. A comprehensive model of a transformer winding is presented, meticulously incorporating skin and proximity effects. The winding resistance increase due to these effects is determined by applying analytical and finite element methods. The investigation highlights that eddy current losses in the magnetic core notably increase the resistance of each winding section in low frequencies. However, the impact of these losses diminishes as the winding length approaches the voltage wavelength at high frequencies. Consequently, the net magnetomotive force and flux in the core become negligible. As a result, the high-frequency impedance characteristics are remarkably similar for windings with and without a magnetic core. These findings are substantiated through rigorous simulations and empirical measurements.

Highlights • A new effective approach of online power system inertia calculation is presented. • An improved method of Estimation of the Rate of Frequency Change is proposed. • It increases the awareness of the varied and reduced system inertia in future power system. • The performance is validated by simulations, under laboratory conditions and real-life data. • The method uses wide area monitoring data and can be part of application of WAMPC scheme. Abstract Future developments in power systems, e.g. relatively larger generator sets, the virtual power plant and synthetic inertia concept and connection of generation assets over inverters, will cause the system inertia to vary significantly. During system operation, if the inertia of the system is significantly lower than anticipated at the planning stage, then the existing, deterministic protection and control may fail to ensure system stability. Therefore, the ability to accurately determine the inertia of individual system areas, and the system as a whole, online would be very useful. In this paper, an Inertia Calculation Application (ICA), which could be implemented as part of a Wide Area Monitoring Protection and Control scheme, is presented. The necessary wide area measurements must be processed during large disturbances to the active power balance of the system. The ICA has been validated by using computer simulations, under laboratory conditions and by using real-life data recorded by a transmission system operator. [ABSTRACT FROM AUTHOR]

Power systems require a reliable supply and good power quality. The impact of power supply interruptions is well acknowledged and well quantified. However, a system may perform reliably without any interruptions but may have poor power quality. Although poor power quality has cost implications for all actors in the electrical power systems, only some users are aware of its impact. Power system operators are much attuned to the impact of low power quality on their equipment and have the appropriate monitoring systems in place. However, over recent years certain industries have come increasingly vulnerable to negative cost implications of poor power quality arising from changes in their load characteristics and load sensitivities, and therefore increasingly implement power quality monitoring and mitigation solutions. This paper reviews several historical studies which investigate the cost implications of poor power quality on industry. These surveys are largely focused on outages, whilst the impact of poor power quality such as harmonics, short interruptions, voltage dips and swells, and transients is less well studied and understood. This paper examines the difficulties in quantifying the costs of poor power quality, and uses the chi-squared method to determine the consequences for industry of power quality phenomenon using a case study of over 40 manufacturing and data centres in Ireland. [ABSTRACT FROM AUTHOR]

This paper presents a novel wavelet based approach for fault location using voltage transient waveforms in power distribution systems. The proposed method includes two main stages. Firstly, the approximate location of the fault or fault section is determined using a new algorithm with discrete wavelet transform. The difference between arriving times of transient components in different measurement units is used for this purpose. The accurate location of the fault is determined in the second stage. Depending on the determined fault section, the difference between arriving times of transient components in different measurement units or the frequency content of the voltage transients are used. The time difference and frequency content are calculated using discrete and continuous wavelet transform (DWT and CWT) respectively. The proposed technique is implemented on an unbalanced 34 bus distribution system with two distributed generation units which is simulated in ATP–EMTP. The comparison of the results of the proposed method with previous works verifies its better accuracy and more robustness to fault conditions including fault inception angle and fault resistance. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new power quality index is defined, tested and established. [•] New index is based on weighted sum of percentage energy deviation from pure signal. [•] 133 Signals as per IEEE 1159-2009 standard are used for validation of new index. [•] Real transients acquired by laboratory experimentations are used for validation. [•] New index is compared with THD and other discrete wavelet transform based index. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a method for the analysis of electromagnetic transients in multiphase transmission networks using the Numerical Laplace Transform. The proposed procedure is based on the superposition principle and is applied to switching and non-linear elements modeling. Switching operations are modeled as initial condition problems by means of injected current sources. In the case of non-linear elements, a piece-wise linear approximation is made, which reduces the problem to a sequence of switching operations. Several applications and comparisons with results obtained with the EMTDC and ATP programs are presented. [Copyright &y& Elsevier]

For a power industry undergoing deregulation, the growing number of power marketers and independent power generators increases the variability of power flow patterns in an interconnected power system, thereby making the prediction of critical operating conditions and limits more demanding. Consequently, transmission system operators need new tools to understand the effects of disturbances. Among these needs are tools to classify and identify disturbances as they occur on the power system. In this paper, power system disturbance data from the Northfield substation dynamic recording device in the US New England power system are analyzed and their features extracted. Then a classification method is used to identify the disturbance. Events with multiple disturbances are also addressed. A MATLAB-based software, called ‘Event Analyzer’, has been developed for the disturbance identification. [Copyright &y& Elsevier]

• A PEM Fuel Cell model covering the multi-physics transients is developed. • The representation of the model is based on electric circuit equivalents. • It is shown how the model is realized in a network simulator for electric transients. • The multi-physics PEMFC model is validated against experimental reference data. • A CHP application is carried out to verify the value of the modeling. Digital simulators of electric networks have been indispensable tools for engineers and researchers engaged in the analysis and design of electric power and energy systems. With the increasing interest to extend electric energy toward multi-energy systems covering multiple energy carriers, there arises a need to also extend the capabilities of today's simulators. Such an extension is proposed here in the form of a Proton Exchange Membrane Fuel Cell (PEMFC) model that covers the multi-physics transients involved in the flows of the electric current, hydrogen and other gases, and the enthalpy. The modeling makes use of given analogies to allow for a uniform representation of electric, pneumatic, and thermal transients based on electric circuit equivalents. It is shown how these models representing different transients are coupled as part of a PEM fuel cell system. Validation and application are carried out to verify the value of the modeling. The investigations are performed with an electric network simulator of type EMTP (Electromagnetic Transients Program) and so substantiate the possibility of using the latter for studying multi-energy systems. [ABSTRACT FROM AUTHOR]