Transient Electromagnetic Disturbance Research Articles

Test Methods for Performance of Protective Devices Excited by Conducted Transient Electromagnetic Disturbance

Test Methods for Performance of Protective Devices Excited by Conducted Transient Electromagnetic Disturbance

Cable Coupling Characteristics of Wireless Network Convergence Nodes by Transient Electromagnetic Fields in Intelligent Substations

Switching operations in intelligent substations generate a wide range of extremely strong and asymmetric transient spatial electromagnetic fields, and this complex transient electromagnetic field can have a coupling effect with the wireless network sink node equipment cables. We conducted a study on the networking method of wireless network equipment in smart substations and analyzed the types of sink node cables used. In the GIS room of the 110 kV GIS smart substation, the transient spatial electromagnetic field generated by switching operation and the transient induced current of the sink node cable under different operating conditions were tested and obtained, and the time domain and frequency domain comparative analysis was performed. A near-field coupling model of the asymmetric and non-uniform cable transient spatial electric field at the sink node is established, and the validity of the model is verified by comparing and analyzing the measurement and simulation results. The results of the study can provide a reference for transient electromagnetic disturbances in 110 kV GIS intelligent substations and contribute to improving the reliability of wireless network equipment operation.

Experimental Study on Response of Non- and Externally-Gapped Metal-Oxide Arresters Excited by Nanosecond-Level Transient Electromagnetic Disturbances

Metal-oxide arresters (MOA), including the non-gapped MOAs (NG-MOA) and externally-gapped MOAs (EG-MOA), are the main equipment applied to protect the power system against conducted transient electromagnetic disturbances (TED). However, MOAs exhibit quite different electrical characteristics under microsecond-level and nanosecond-level transients. In order to figure out the response of MOAs under nanosecond-level TED, experimental platforms are built which contain a pulse generator with the amplitude of pulse current adjustable from 0 kA to 5 kA and the rise time of 20 ns. Then the dynamic hysteresis loops, the static V-I characteristics, the response time delay and the full response process of five types of 10-kV MOAs are investigated. From the dynamic hysteresis loops of NG-MOAs, the impedance conversion process can be seen clearly and can be explained by the grain-boundary theory. But EG-MOAs has not this conversion process due to the air-gap. And the experimental results demonstrate that there is no noticeable nanosecond-level conduction delay on NG-MOAs whereas the electric field non-uniformity of the air-gap has a significant influence on the time delay of the EG-MOAs. The response time delay of EG-MOAs changes ranging from tens of nanoseconds to hundreds of nanoseconds. This feature makes EG-MOAs more likely to raise insulation risks under nanosecond-level TED compared with NG-MOAs.

Influence of Temperature on the EFT Immunity of Multistage Integrated Oscillators

The reliable operation of an integrated circuit (IC) can be affected by transient electromagnetic disturbances and temperature variations. In this paper, the performance of three oscillator circuits, namely 3- and 5-stage current-starved voltage controlled oscillators and a 3-stage ring oscillator, is compared with respect to electrical fast transients (EFT) under the influence of thermal stress. The main objective is to compare and assess, by means of measurements, the EFT immunities of integrated oscillators with the same electrostatic discharge (ESD) protections but different circuit topologies. The failure modes caused by EFT are proposed based on the considered failure criterion. Moreover, the importance of the IC package on the immunity levels of each oscillator is investigated. The output frequency response of each oscillator to the combined EFT and temperature stresses is analyzed without the external parasitics. The results show that the 5-stage CSVCO is most resilient towards temperature variations, whereas it is the least immune to the combined effect of EFT and temperature. Moreover, a distinct behavior in each tested oscillator's frequency is observed for the in-phase EFT injections due to the topology of the circuit. Relevant MOSFET characteristics such as on-state drain-to-source resistance, power dissipation, effective mobility and threshold voltage are further analyzed under the influence of thermal stress and EFT. The root cause of higher EFT susceptibility of the 5-stage CSVCO is found to be the considerable variation of the on-state resistance due to the combined reduction of effective mobility and absolute threshold voltage levels of the MOSFETs.

Vulnerability Assessment of Equipment Excited by Transient Electromagnetic Disturbances Based on Distribution-Free QMU Method

Based on the framework of quantification of margins and uncertainties (QMU) method, a distribution-free QMU method is proposed for the vulnerability evaluation of electrical and electronic equipment excited by transient electromagnetic disturbances. The proposed method can provide a comprehensive evaluation of the equipment considering the stress and the strength with uncertainties. The stress is represented by the induced responses on the equipment conductors, the strength is quantified by the occurrence probability of failure obtained from the experiment. The quantile-based QMU metric can take account of the inherent probability characteristics of stress and strength, as well as the aleatory uncertainties caused by sampling variability. The quantiles and their tolerance bounds are estimated by a nonparametric estimation method based on order statistics, which is a data-driven method without being constrained by the type of probability distribution. A case study of an electronic equipment in the power plant is carried out to illustrate the evaluation procedures of the proposed method.

A Test Method for Response Behavior of Metal-Oxide Arrester Subjected to Transient Electromagnetic Disturbances

Metal-oxide arresters (MOA) are widely used to protect equipment against transient electromagnetic disturbances (TED) like very fast transient overvoltage (VFTO), high-altitude electromagnetic pulse (HEMP), lightning pulse, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al.</i> Researches on the performance of MOA under microsecond level rise-time TED are abundant, such as lightning pulse. However, when MOA is subjected to TED of rise-time at nanosecond level, the voltage/current responses of MOA are not fully studied due to the lack of a standardized and reliable test setup. In this paper, a test setup is proposed for acquiring the response behavior of MOA under nanosecond level pulse. The setup is comprised of a pulse generator, a two-branch transmission line system and a high voltage power divider. The generator can provide stable double exponential pulse with tunable rise-time ranging from 5 ns to 100 ns. The divider ensures an even distribution of voltage/current surge wave along the two-branch line. Through the numerical analysis, both impinging and residual surge waveforms could be retrieved from measurements. The proposed method has been applied to investigate response behavior of MOA subjected to nanosecond level rise-time pulses.

Experimental Study on the Transient Disturbance Characteristics and Influence Factors of Pantograph–Catenary Discharge

The transient electromagnetic disturbance generated by arcing discharge between the pantograph and catenary can pose a significant risk to the safe operation of electrified railways. In order to better comprehend its properties, a pantograph–catenary discharge generating device is designed to simulate the discharge phenomenon with moving electrodes in this experimental investigation. The effects of the applied voltage, the gap distance, and the relative motion between the pantograph and catenary on the time- and frequency-domain features of the discharge current and electromagnetic field are investigated. The variation trends of pulse peak current, rise time, pulse repetition frequency, maximum amplitude, and characteristic frequency in the radiation spectrum are retrieved under varying experimental settings, and the effect mechanisms are derived from the physics of gas discharge. A dynamic discharge test is conducted in this study in order to further understand the effect of electrodes’ relative motion on discharge characteristics. The results indicate that lateral sliding motion of the pantograph along the track has a negligible effect on the transient discharge, whereas a faster vertical approaching motion between the pantograph and catenary generates a larger pulse current peak, a steeper rise front-edge, and a higher radiation intensity.

Vulnerability Assessment Method for Electronic Devices Excited by Transient Electromagnetic Disturbances

Vulnerability assessment of electronic devices excited by various transient electromagnetic disturbances (TEDs) has been a key issue in electromagnetic susceptibility research. This paper proposes a generalized vulnerability assessment method that includes acquiring data and building assessment model. The data is normally acquired by carrying out experiments, while the assessment model is mainly determined by prior information. As different devices under test (DUTs) could offer a different amount of prior information, a generalized assessment model consisting of a white-box model, a grey-box model, and a black-box model is built to deal with situations of sufficient prior information, partial prior information, and no prior information, respectively.

A high-efficiency wideband coupler for nanosecond-level pulsed current injection.

Pulsed current injection (PCI), as a conducted vulnerability testing technique under nanosecond-level transient electromagnetic disturbance (TED), has gained great attention recently. Many kinds of TEDs, e.g., high-altitude electromagnetic pulse, very fast transient overvoltage, and electrical fast transients, have very fast rise time as well as pretty slow decay, whose frequency spectrum may cover a very wideband. Therefore, one of the challenges is that the existing inductive couplers cannot interact with the equipment under test (EUT) over the wideband efficiently, and consequently, they are inadequate to inject the proper disturbance at ports of EUT in PCI tests. To address this problem, a high-efficiency wideband PCI coupler is proposed in this paper. The coupling performance is analyzed theoretically based on the distributed-parameter model of an inductive coupler. By using the composited ferrites instead of the simplex Ni-Zn ferrites, the inductive coupling is enhanced. The capacitive coupling is also enhanced to improve the high-frequency performance by exploiting the distributed tubular winding. A PCI coupler with the dimension of 30 × 10 × 10cm3 is built to be validated experimentally. The 3 dB bandwidth has been improved from 421 kHz-14MHz to 77 kHz-39MHz, which indicates that the coupler can be applied efficiently over the frequency range of interest for PCI tests.

A transient electromagnetic disturbance testing system based on low-frequency-compensated symmetric TEM horn antenna.

A transient electromagnetic disturbance (TED) testing system with an adjustable direction of polarization is developed in terms of a low-frequency-compensated symmetric transverse electromagnetic (TEM) horn antenna in this paper. TEM horn antennas are deficient in the low-frequency radiation, which would lead to a very narrow pulse width and cannot be directly applied in radiation tests of TED, especially the TED with abundant low-frequency components such as fast transient overvoltage and high-altitude electromagnetic pulse. To address this problem, a theoretical radiation model and a design principle of the back-loading method are proposed to compensate for the low-frequency performance. After the optimization of the structure according to the simulated results, a TED testing system with the aperture width of 0.9 m and the length of 1.8 m is built. The rise time of the electric field measured at the center of the aperture is 2.39 ns, the pulse width is 27.65 ns, and the peak field is over 50 kV/m, which can meet the requirements of relative standards. The dimension of the working volume is estimated as 0.4 × 0.5 × 0.5 m3 according to the field distribution.

Vulnerability Assessment of Equipment Excited by Disturbances Based on Support Vector Machine and Gaussian Process Regression

In this article, a nonparametric vulnerability assessment method is proposed for the equipment excited by transient electromagnetic disturbances. By carrying out the proposed method, the probability distributions of multistate failure thresholds could be obtained for the cases of lacking prior knowledge, such as the effect mechanism, related distribution characteristics and training data. In fact, the proposed method combines support vector machine (SVM) and Gaussian process regression (GPR). SVM may extract the classification hyperplane from a small number of test samples, and obtain the continuous classification indicators subsequently. Furthermore, the regression results of classification indicators based on GPR can provide both mean values and their confidence intervals. To deal with the multilevel effect assessment, the “one against the rest” strategy is applied and probabilities of each level can be assessed simultaneously. Finally, a case study of an electronic system is carried out to illustrate the applicability and effectiveness of the proposed method.

Response of 10-kV Metal-Oxide Surge Arresters Excited by Nanosecond-Level Transient Electromagnetic Disturbances

Nanosecond-level transient electromagnetic disturbance (TED), including very fast transient overvoltage caused by operation of disconnectors, high-altitude electromagnetic pulse, and many other fast transients may interfere or even damage the electrical equipment. As one of the main overvoltage protective equipment, the protective performance of metal-oxide surge arresters (MOAs) under nanosecond-level TED should be investigated and then compared with that under microsecond-level TED, especially the lightning impulse. Based on a testing platform containing a 400-kV pulse generator with adjustable rise time from 5 to 100 ns, the behaviors of nonlinearity, fast impulse response, and converting impedances of three types of 10-kV MOAs under TED with different rise time were explored experimentally in this article. The peak residual voltages of 10-kV MOAs under TED with the rise time of 5 ns at 5 kA are 50.2-60.7% higher than those under the lightning impulse. The rise time of TED has significant influence on the peak voltage and impedance converting behaviors of MOAs. A circuit model of 10-kV MOAs under nanosecond-level TED is built and validated by experimental results, which can be applied in insulation coordination and design of protective devices against TED.

10-kV Transmission Line Experimental Platform for HEMP Immunity Test of Electrical Equipment in Operation

To investigate the high-altitude electromagnetic pulse (HEMP) immunity of electrical equipment in operation, a 10-kV transmission line (TL) experimental platform is built in this paper. The conducted transient electromagnetic disturbance (TED) could be injected to the electrical equipment of 10-kV TL with power on or power off. The TED is produced by the pulsed current injection (PCI) generator, whose rise time is less than 20 ns and full width at half maximum is in the range of 500 ~ 550 ns on short-circuit state with 60 Ω resistor. On the other hand, the 10-kV TL is equivalently designed in cross section to make its characteristic impedance being 330 Ω to conform to the value of practical case. The voltages and currents applied on the tested equipment can be measured at nano-second level simultaneously, which are of great use to learn the effect mechanisms and compare the results under different working conditions. Some 10-kV pin-type porcelain insulators are tested under different conditions, which shows the capacity of the proposed platform to test immunity of 10-kV electrical equipment.

A Fully Coupled Numerical Method for Coated Conductor HTS Coils in HTS Generators

Superconducting rotational generators are a promising application of the high temperature superconductor (HTS). Typically, superconducting rotating generators use HTS coated conductors to form the DC coils in the rotor as they experience lower AC loss compared to the stator windings. However, in the actual operation, the AC loss produced by the harmonic magnetic field is inevitable. Other transient electromagnetic disturbances in the operating generator environment can also cause the AC loss. This paper introduces a fully coupled numerical method for coated conductor HTS coils in operating generators based on the T-A formulation, which is verified by almost the same simulation results with the A-H formulation model. Using this method, the simulation results show that the ferromagnetic stator teeth will increase the AC loss caused by the harmonic magnetic field and the load change, while the shielding layer can decrease the AC loss in a certain amount.

Statistical Inference of Serial Communication Errors Caused by Repetitive Electromagnetic Disturbances

Communication errors can be caused by transient electromagnetic disturbances, making the related protection and avoidance measures highly demanding. In this article, we propose a statistical method to infer error mechanisms of serial communication errors caused by repetitive electromagnetic disturbances. An experimental investigation has been conducted by introducing crosstalk disturbances on the transmission cable, resulting in various communication errors. To determine the corresponding failure mechanism for these errors, a hypothesis test method is introduced. First, the bit-flip error on the basis of the known mechanism is simulated through the Monte Carlo method, so that a null hypothesis can be established. Then, by applying a modified chi-squared test, researchers can investigate the influence of multiple pulses on the occurrence probability of bit errors. As a result, nonlinear effects such as energy saturation or accumulation of the transceivers can be discovered. The validated results show that the proposed method has a good performance to determine the known mechanisms of communication errors and infer new regularities with a given significant level.

Bayesian Inference for Susceptibility of Electronics to Transient Electromagnetic Disturbances With Failure Mechanism Consideration

It is a necessity to evaluate the susceptibility of electronics to transient electromagnetic disturbances, such as electromagnetic pulses, lightning, electro-static discharges, and switching pulses. One can conduct experiments on the system of interest and analyze the result through statistical inference for the relationship between electromagnetic excitations and effect phenomena. However, since conventional statistical models are driven by experimental data, it might result in inappropriate explanations of the effect mechanisms due to limited samples, leading to over- or under-estimations. To address this problem, we propose a hybrid model that combines the statistical estimation with the known failure mechanism obtained from either the theoretical analysis or the empirical evidence. The physical cause can be drawn from the mechanism analysis, and then a statistical classifier is introduced to build the relationship between the causes and the effects. Based on Bayesian assessment, all the parameters involved are estimated with the Markov chain Monte Carlo method. Numerical simulation results have verified that the model is capable of estimating the susceptibility of electronics with given failure mechanism assumptions and limited test samples. In the end, the breakdown characteristic of the gas discharge tube is investigated to demonstrate the applicability of the proposed model.

Pulsed Current Injection Setup and Procedure to Reproduce Intense Transient Electromagnetic Disturbances

In this letter, a pulse current injection (PCI) setup involving a pulse generator with adjustable parameters is designed and modeled in SPICE. In order to allow causal and accurate time-domain simulation, the circuit model makes use of an augmented network to approximate the non-rational frequency response of the injection probe. The obtained SPICE model is preliminary validated by measurement for different sets of values of the pulse-generator parameters. Afterward, an explicative example of radiated test setup is considered. The stress waveform induced at the points of entry of the equipment under test by radiation (evaluated either by theoretical prediction or by measurement in a low-level radiation environment) is taken as reference to prove the effectiveness of the proposed PCI-setup model in identifying the values of the generator parameters required to reproduce the same disturbance by PCI.

Transient Electromagnetic Disturbance Induced on the Ports of Intelligent Component of Electronic Instrument Transformer Due to Switching Operations in 500 kV GIS Substations

Switching operations in gas-insulated switchgear (GIS) substations generate transient electromagnetic fields in the GIS pipes. These fields leak out discontinuities of the GIS and induce electromagnetic disturbance voltages on the cables and ports of secondary circuits. In smart GIS substations, secondary devices especially, such as the intelligent component of electronic instrument transformer, are vulnerable to electromagnetic interference. In this paper, the disturbance voltages induced on the ports of intelligent component of electronic instrument transformer had been measured in three 500-kV GIS substations, respectively. The disturbance was generated either during disconnector (DS) switching operations or circuit breaker (CB) operations. Then, the time-domain and frequency-domain characteristics of the disturbance waveforms have been analyzed. The micro-pulses of disturbance voltages have been extracted from the raw data. The waveform parameters, including peak voltage, rise-time, dominated frequency, and duration, have been calculated by the statistical analysis. The comparison between disturbance during DS switching operations and that of CB operations has been made. Also, the differences and similarities of disturbances between the three GIS substations have been displayed. Furthermore, the differences between measured waveforms and the IEC 61000-4-18 immunity test standard waveform have been discussed.

Measurement of transient electromagnetic coupling and interference caused by disconnector operation in substation

Abstract Disconnector operation in the substation can cause transient electromagnetic disturbance and very fast transient over-voltage (VFTO), and will lead to the misoperation or damage of electrical protection system. To research the characteristics and influence of electromagnetic interference, principle of disconnector operation was analyzed. Then, an improved Agrawal model was adopted to describe the transmission line coupling process of disconnector operation, and telegraph equation was calculated by finite-difference time-domain (FDTD) method. With the model and method, the conduction process and characteristics of transient electromagnetic coupling and interference caused by disconnector operation in substation were simulated. Besides, disturbance voltage signal on the secondary cables caused by disconnector operation was measured in a 500 kV substation. Finally, parameters of transient electromagnetic coupling and interference in time domain and frequency domain were calculated respectively. Experiment results show that the quantitative level of transient electromagnetic coupling and interference caused by disconnector operation in substation can be evaluated in theory, and the core frequency points concerned in secondary circuit can be calculated.

Disturbance Voltage Induced on the Intelligent Electronic Device Ports due to Switching Operations in Gas Insulated Substation

There is great concern on the electromagnetic compatibility problem of electronic equipments in an intelligent substation, due to the compact structure resulted from high degree of integration between the primary electrical equipments and secondary electronic equipments. The very fast transient electromagnetic disturbance (VFTED) resulted from the gas insulated substation (GIS) switching operation has potential impact on the electronic equipments by the electromagnetic coupling between the VFTED and the circuit of “sensor-cable-intelligent electronic device (IED)”. This paper presents both experimental and theoretical results of the disturbance voltage induced on the ports in control cabinets during the disconnectors operating in a 500kV GIS substation. The considered ports are connected to a current transformer (CT) equipped nearby GIS switcher via a KVVP cable. The results show that the peak value, the duration time and the frequency range of the transient waveform are about 400V, 2 μs, and below 40 MHz.