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This study proposes an alternative method to calculate the transient responses of multi‐conductor overhead transmission lines based on ABCD representation, recursive convolutions and numerical method for rational approximation in the frequency‐dependent curves. In the classical universal line model, the characteristic admittance matrix Yc(ω) and propagation matrix H(ω) are represented by rational functions. In H(ω), previous and correct identification of the modal travelling times is required. However, these modal travelling times are estimated numerically, which do not offer good accuracy in some cases. This fact has a considerable effect on the rational representation of H(ω) itself and consequently on the transient responses. In the alternative method, a previous estimation of the modal travel times is unnecessary because when using the ABCD representation for each propagation mode, a direct relation exists between the currents and tensions of the receiving and sending ends. These relationships are fitted by smooth rational functions, and then, using recursive convolution methods, the authors obtain the explicit equations of the currents and voltages to calculate the transient responses. The results demonstrate that the alternative method is accurate when compared with the frequency‐domain solution of the transmission line transformed to the time domain using the numeric Laplace transform and with the Bergeron method. [ABSTRACT FROM AUTHOR]

The essence of the mathematical model of disconnectors' multiple reignition arc is the repeated breakdowns of SF6. In this study, the kinetic properties of microparticles are studies based on the streamer discharge theory, and a fluid arc mathematical model applied in centimetre clearance is established. Ultra‐High Voltage (UHV[AQ ID=Q1]) disconnector manufactured by Pingao Electric Co. Ltd of Henan Province is selected as the object and the resistance change process of contact clearance multiple reignition arc is simulated by finite difference method‐finite element method‐flux corrected transport self‐programming in MATLAB based on the chamber structure and operating characteristics. UHV gas‐insulated switchgear very fast transient overvoltage (VFTO) test platform is built to gain the characteristics of VFTO waveforms generated by the disconnector's operation. Compared with simulation results, the test data shows that the fluid arc mathematical model can scientifically explain the dynamic development process of microparticles in the contact clearance and the calculation results are consistent with the test data. In addition, the arc fluid mathematical model combines the structure and operating characteristics of the switch with the development process of microparticles, which can better guide the design of the switch, and provide a theoretical basis for the suppression of VFTO with the disconnector itself. [ABSTRACT FROM AUTHOR]

Transient voltages from (dis)connecting compensation coils near high voltage transformers are studied. Non‐invasive sensors are needed in order to exclude any influence by the measurement equipment on the overvoltage magnitude. This study describes results from open‐air capacitive sensors as part of a differentiating/integrating measurement system. Its bandwidth (up to 10MHz) allows to record large detail in the switching events. However, the coupling strengths and the cross‐couplings inherent to the use of air capacitive sensors need to be determined. Calibration based on symmetric phase voltages during normal operation supplies part of the information. Three methods are compared to supplement this knowledge for establishing the complete coupling matrix between phase conductors and sensors. One method employs estimates from the system configuration, in particular, its symmetry. The other techniques extract information from fast transient events within the responses for both switching on and off. The decoupled waveforms from different methodologies align within their confidence bounds and predict the maximum overvoltage magnitudes within an accuracy of 5% when employing information from the fast transients. Based on measurements performed on two compensation coils, both tested three times, larger overvoltages occurred during energisation compared to de‐energisation with maximum amplitude exceeding three per unit. [ABSTRACT FROM AUTHOR]

The authors use a TMS320 digital signal processor (TMS320‐DSP) to determine fault instants and estimate their location in real time in a laboratory environment. The fault instant is determined via examining the instantaneous differential changes in the line currents. After the fault is detected, the fault location is determined by processing the time‐domain transient current waves. First, the travelling‐wave frequency is determined by application of the fast Fourier transform to the positive‐sequence‐component line current after the fault, and subsequently, the fault location is estimated by utilising this frequency. The alternative transients programme (ATP)–electromagnetic transient programme is used to simulate the line currents and create short‐circuit fault conditions. Furthermore, LabVIEW software and a National Instruments data acquisition board are used to transform the line currents obtained through the ATP programme into analogue signals. The TMS320‐DSP determines the fault in real time and estimates the fault location using the completed software and analogue input signals. Their results indicate that the prototype device designed with the use of the TMS320‐DSP is suitable for real‐time fault detection. [ABSTRACT FROM AUTHOR]

This study presents an efficient current tracking method of power frequency signals using Rogowski coil. To compensate the output voltage of the Rogowski coil, a direct and simplified digital compensation technique is proposed to reconstruct the input current. Different high‐frequency reconstructing techniques are used to emphasise estimating and reforming the fundamental input current from Rogowski coil output. Then, a new method is presented for extracting the fundamental current phasors from the Rogowski coil by processing its terminal voltage using the discrete Fourier transform. For experimental evaluation, a digital signal processing board‐based test setup is utilised. For the simulation study, accurate Rogowski coil modelling in alternative transients programme–electromagnetic transients programme is developed to evaluate the proposed method under special testing conditions concerning step change and DC decay. The results validate the efficacy of the proposed method in power frequency tracking for metering and protective relaying purposes. [ABSTRACT FROM AUTHOR]

Transients from lightning strikes can enter underground cables at overhead line to power cable transitions. Possible overvoltages on these surges at cross‐bonding connections of the cable screens are of major concern. A model is developed for modelling overvoltages from transient signal propagation through a combined cross‐bonding cable and box. This model is applied to the first Dutch 400 kV cable connection. Such model incorporates model parameters whose values depend on design details of the cross‐bonding box. The values for these model parameters are extracted from the measured transmission and reflection signal on steep pulses injected into the actual cross‐bonding box configuration. The model combines transmission line description for the cross‐bonding cables with mainly inductive behaviour of the cross‐bonding box. The obtained results are verified by measurements. The model is applied to investigate overvoltages induced at the cross‐bonding cable and box on 1.2/50 µs impulse voltage injection representing a lightning impulse voltage applied to the core conductor of the cross‐bonding cable. Furthermore, the effectiveness of surge arresters to reduce overvoltages at the cross‐bonding cable screen is demonstrated by simulations with this model in PSCAD. [ABSTRACT FROM AUTHOR]