Current Interruption Tests Research Articles

Electromagnetic disturbance characteristic of typical high voltage switchgear interruption process in offshore wind farm based on integrated conduction model

AbstractIn an offshore wind farm, a high‐voltage switchgear interruption in an offshore substation creates a high‐frequency, high‐amplitude overvoltage that can cause severe electromagnetic interference problems in the intelligent electronic device. To address this issue, mathematical models, vector fitting and finite element method were used to build an integrated electromagnetic disturbance conduction model, whose accuracy was verified by large current interruption tests. Through the simulation of a typical offshore wind farm's single‐phase grounding fault interruption process, the electromagnetic disturbance characteristics and the impact of the ground position are obtained. The results show that during the fault interruption process of phase B grounded, the dominant frequency of disturbance voltage can reach 4.34 MHz, and the amplitude can reach 1.12 kV. The ground grid has a large impact on the interference voltage, which can reach a maximum value of 2.28 kV under specific conditions. The disturbance voltage in the fault process mainly comes through the current transformer, while during the interruption process, it mainly comes through the ground grid. The authors provide a method to establish the integrated electromagnetic disturbance simulation model, which can improve the accuracy of the electromagnetic disturbance conduction process simulation of intelligent components.

Study on Short-circuit current interruption characteristics of Double-break fast vacuum circuit breaker within the minimum arcing time

It is significant for circuit breakers to expel a short-circuit fault in a short time for the new power grid with high proportional photovoltaic or wind power plants to achieve high transient operating stability. Compared with a traditional circuit breaker, a fast vacuum circuit breaker (FVCB), operated by an electromagnetic repulsion actuator, has an extremely shorter opening time and lower deviation in their opening times. This potentially contributes the FVCBs to interrupting a short-circuit fault current in the first half-wave when introducing a controlled switching technology. Meanwhile, it is beneficial to improve the short-circuit current breaking capacity of the FVCBs by adopting series-connected double-break circuit breaker technologies. This paper aims to explore short-circuit current interruption characteristics of a double-break FVCB within the minimum arcing time. We performed a series of short-circuit current interruption tests in a Weil synthetic test circuit. Two series-connected FVCBs and independent single-break FVCBs were used. Three different kinds of opening velocities were adopted for each of the FVCBs. Results showed that the increase in opening velocity resulted in both a decrease in the minimum arcing time and the critical arc extinguishing contact gap, whether for the single-break or the double-break interruption tests. The ratio of the shared voltage on each of the series-connected FVCBs was about 54 (for the break on the high-voltage side) and 9 (for the break on the low-voltage side). Taking the break with a shorter opening time as a break in the high-voltage side could reduce the minimum arcing time and the critical arc extinguishing contact gap. At the same opening velocity, the sum of the critical arc extinguishing contact gap of the two breaks in double-break interruption tests was significantly higher than twice the critical arc extinguishing contact gap in the single-break interruption tests. This could be caused by the fact that in double-break interruption tests, after the breakdown of one break, even if the break restored insulation, could not share the transient recovery voltage (TRV) before the break broke down. In addition, the sudden drop of TRV without breakdown occurred for the break on the high-voltage side might correlate with the micro-discharge of the vacuum gap. The interaction of the charged particles with the electrode surface would be responsible for the formation and evolution of the micro-discharge in some successful interruption cases.

Integration of superconducting fault current limiter with solid-state DC circuit breaker

The onboard direct current (DC) system in electric aircraft could face a severe fault current, which is tens of times the nominal current in a short-circuit fault. It is critical to limit the fault current and clear the fault within a few milliseconds to prevent any damage to the DC system. A protection method using a resistive superconducting fault current limiter (SFCL) with a solid-state DC circuit breaker (SSCB) to manage the DC short-circuit fault is proposed and experimentally verified. A bifilar SFCL coil prototype with two types of connection to achieve low and high inductance is designed and tested, which reduces the fault current considerably from 2000 A to below 1000 A. The performance when integrating the low and high inductance SFCL with a solid-state DC circuit breaker are investigated. It is found that when integrating the SFCL with the SSCB, a high voltage is induced across the high inductance SFCL during current interruption tests. In terms of reliability and durability, the low inductance SFCL is preferred to integrate with the SSCB. The experimental results show that the low inductance SFCL can be an effective solution to protect the DC system from severe fault currents and then SSCB can rapidly and reliably interrupt the fault current at 1000 A.© 2017 Elsevier Inc. All rights reserved.

A Relationship Between Vacuum Arc Characteristics and Short-Circuit Current Interrupting Capability at Minimum Arcing Times

The study is to explore a relationship between vacuum arc characteristics and short-circuit current interrupting capability of a fast vacuum circuit breaker (FVCB) at a minimum arcing time. Both a short-circuit current interruption test and an arc mode transition observation test were carried out to explore the relationship. Firstly, an FVCB with ceramic enclosure vacuum interrupter (VI), in which a pair of axial magnetic field (AMF) contacts were arranged, was operated with three different opening speeds to interrupt short-circuit currents. A Weil synthetic circuit provided short-circuit currents of 20, 30, and 40 kA, and a transient recovery voltage (TRV) of 92 kV/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$120~\mu \text{s}$ </tex-math></inline-formula> for the short-circuit current interruption capability experiment. Then, the arc mode observation experiment was carried out under the same conditions as the short-circuit current interruption capability experiment, except for two differences, that is, a glass enclosure VI without a shield was used for observing the arc with a high-speed camera, and the other point was that only the short-circuit current was applied and no TRV was applied. Experimental results showed that the increase in the opening speed resulted in a decrease in the minimum arcing time, the critical arc extinguishing gap, and the critical arc diffusion time, but led to an increase in the maximum arc column diameter. In contrast, the increase in the short-circuit current would increase the minimum arcing time, the critical arc extinguishing gap, the critical arc diffusion time, and the maximum arc diameter. The diffusion of the arc column is essential but not sufficient for the successful interruption. The contact gap plays a significant role. On the one hand, a larger contact gap promotes arc diffuse. The arc diffusion can decrease the contact surface temperature and the local particle density at current zero. On the other hand, a larger gap distance leads to a smaller electric field intensity between fixed and moveable contacts, which reduces the breakdown probability during the postarc dielectric recovery. The critical arc energy density for a successful interruption of the FVCB in short arcing times was obtained to range from 0.54 to 1.01 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times \,\,10^{8}$ </tex-math></inline-formula> J/m3.

Thermal FEM Analysis of Surge Arresters During HVdc Current Interruption Validated by Experiments

This paper deals with the development of an accurate finite-element model of an arrester to investigate the electrothermal and mechanical stress during dc current interruption. The comprehensive analysis performed on a ZnO surge arrester is supported by experiments during high-voltage dc circuit breaker current interruption. The performed experimental analysis comprises three sequential 26 kV/10 kA direct current interruption tests carried out within a period of one hour. The dynamic temperature and current distribution of the surge arrester columns during current interruption are measured. The finite-element simulation results are in good agreement with the test results. The influence of the surge arrester temperature on the current distribution among the surge arrester columns is analyzed. The impact of the surge arrester temperature on ZnO electrical characteristics and mechanical stress inside the surge arrester are also investigated. The surge arrester finite-element model can be used with full success for parameter optimization of the surge arresters to prevent possible failures when dc circuit breakers performed multiple interruptions in short period of time.

Improving Current-Interruption Performance by Using Spiral Electrode for SF6 Disconnecting Switch

To improve current-interruption performance, spiral electrodes were experimentally investigated to magnetically drive an arc. Arcing times for conventional plane electrodes and spiral electrodes were obtained from conducting current-interruption tests and compared. The comparison results indicate that the arcing time in spiral electrodes is about one-third shorter than that in plane electrodes when interruption current is above 900 A. To clarify the principle of improving interruption performance, arc parameters, electrode erosion, and rate of increase in transient recovery voltage were compared for both plane and spiral electrodes. These results revealed that the magnetically driven arc enhances thermal loss of the arc and heat exchange between the arc and ambient gases. Regarding the spiral electrodes, the recovery rate of dielectric strength between the contacts was high. It is thus concluded that current-interruption performance improves by cooling the arc and increasing the dielectric strength by the magnetically driven arc.

Current interruption tests of HVDC circuit‐breakers: Requirements, methods and a testing case

Current interruption tests of HVDC circuit‐breakers: Requirements, methods and a testing case

Lightning protection of multi‐fracture arc‐quenching lightning protection gap for 35 kV distribution lines

Owing to the low insulation level of 35 kV distribution lines, lightning outage accidents and huge economic losses occur frequently. Therefore, a multi-fracture arc-quenching lightning protection gap (MFALPG) for 35 kV distribution lines is developed to ensure the safety and stability of power supply. Here, the principle of MFALPG is presented through the electromagnetic self-contraction effect and qualitative modelling theory. In order to investigate the coupling effect between high-energy compressional waves and arcs, a mathematical model of airflow coupled arc was developed to simulate and analyse the arc-quenching process. Theoretical analysis and simulation results show that the high-energy compressional wave is triggered by the impulse arc rapidly, and the arc conductivity drops abruptly in a short time. Finally, a lightning impulse discharge test and the power frequency withstand voltage test are performed to determine the 35 kV power frequency continuous current interruption test parameters. Under the action of the MFAPLG, the entire time of arc duration is less than 3 ms, and reignition phenomenon of the arc is not found after the subsequent power frequency voltage is restored.

Experimental Study on a Compressed Arc Extinguishing Device for Power Distribution Network

A compressed arc extinguishing device for power distribution network is developed to solve the problem of existing anti‐lightning of power distribution network transmission lines. This paper first introduces the arc extinguishing principle of the arc extinguishing device, and then designs the lightning impulse voltage test around the 10 kV transmission line. The test results show that the U50% Lightning impulse voltage of the arc extinguishing device is 112.4 kV considering the atmospheric correction factor. In order to verify the feasibility of the arc extinguishing device, the power frequency continuous current interruption test is designed. The test shows that the arc extinguishing device can extinguish the arc with a peak value of 1.131 kA in 2 ms and does not reignite in the following time. Finally, the device is applied to a 10 kV power distribution network transmission line of China Southern Power Grid. The lightning trip‐out rate of the transmission line per 100 km is reduced from 12.5 (times/year) to 1.1 (times/year), which fully verifies the feasibility of the arc extinguishing device. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

The effect of a multi-fracture compression airflow arc-extinguishing structure interrupting the power frequency follow current

To reduce the damage from the power frequency follow current of distribution lines, a multi-fracture compression airflow arc-extinguishing structure is studied. The structure is mainly composed of a compression tube, a metal electrode, and metal connection fittings, and the multi-fracture compression airflow arc-extinguishing body is formed by the combination of packaging and insulation fittings. The body and the air gap are parallel to both ends of the insulator. When lightning strikes, the internal short gap of the main body and the air gap break down, and the lightning arc enters the arc-extinguishing body through the breakdown channel. In the structure, the arc is compressed by force to form internal and external gradients of temperature and to produce jet airflow. The jet airflow acts on the subsequent power frequency follow current arc, which is suppressed and extinguished. In this paper, a model coupling an arc and a compressed jet airflow in a multi-fracture compression airflow arc-extinguishing structure is established theoretically and simulated by simulation software. Finally, a power frequency follow current interruption test is carried out. The simulation results show that a high-speed airflow of 600 m/s is formed around the fracture at approximately 0.99 ms, and the airflow is proportional to the rate of temperature variation. The test results show that the power frequency follow current of 1.289 kA is cut off within approximately 3 ms without a reburning phenomenon. The effect of power frequency follow current interruption is obvious in the structure.

A model of the current interruption circuit for hybrid high voltage DC circuit breakers to achieve precise current experiments

The current interruption test based on an LC resonance circuit for hybrid DC circuit breakers (HVDC CBs) is widely employed to characterize the current interruption capability of CBs. In order to ensure a high-fidelity replica of the fault current in a high voltage application, this paper firstly proposes an equivalent model of the test circuit, where not only parasitic resistances but also the threshold voltages and on-state resistances of various semiconductor devices are considered. Moreover, the analytical formula of the test current is derived by including the working principle of the HVDC CB. Secondly, the parameter extraction method, which combines finite element analysis and measurements by impedance analyzer, is given in this paper. The extracted result implies that, in current interruption transient, equivalent resistances of the 500 kV CB is as large as 535 mΩ, having a significant influence on current waveforms. Thirdly, the 34 kV/25 kA current interruption test for the 500 kV CB is conducted. The measured results are proved to be consistent with the analytical results obtained from the proposed model, and the relative error is less than 2%.

Comparison of Different Air Flow Concepts for a Medium Voltage Load Break Switch

The research and development work toward a compact SF $_6$ -free load break switch for the medium voltage range has led to several design proposals. The interruption capability of three different nozzles and gas flow concepts with atmospheric air as the interrupting medium is compared and assessed. The three test switches are installed in circuits corresponding to the mainly active load and switch-fuse test duties of the 24 kV/630 A load break switch standard. A pressure tank is used to provide different air flow rates, and the interruption capabilities of the different flow concepts are compared with basis in the tank pressure required to give successful interruptions. Two hundred and seventy current interruption tests were carried out. Air flows directed radially onto the arc or swirling along the arc turn out to result in a substantially better interruption performance than when the air flows straight and parallel to the arc. Air flows corresponding to upstream over-pressures of a few tenths of a bar seem to be sufficient for an air-based load break switch rated for 24 kV/630 A.

Arcing Contact Gap of a 126-kV Horseshoe-Type Bipolar Axial Magnetic Field Vacuum Interrupters

The objective of this paper is to determine arcing contact gap of a 126-kV horseshoe-type bipolar axial magnetic field vacuum interrupter. Drawn arc experiments were carried out in a demountable vacuum. Experimental current ranged from 12- to 40-kA rms. Based on the vacuum arc behavior, minimum arcing contact gap $D_{1}$ and maximum arcing contact gap $D_{2}$ were defined. When average opening speed within 20 mm ( $v_{1}$ ) was 1.9, 2.3, and 2.6 m/s, $D_{1}$ was determined as 15.3, 16.8, and 14.3 mm, respectively. In addition, $D_{1}$ reflected a peak effect with $v_{1}$ . When average opening speed within 40 mm ( $v_{2}$ ) was 2.6, 2.7, and 2.8 m/s, $D_{2}$ was determined as 38.5, 36.7, and 36.1 mm, respectively. Uncontrollable arc mode appeared when current was higher than 32 kA with arc duration of 9 ms. The critical contact gap to avoid uncontrollable arc mode decreased as a liner function of arc current. Based on the experimental results, quantitative design method of three-interval opening velocity for the 126-kV horseshoe-type vacuum circuit breaker was proposed. For short-circuit current interruption test duty T100s, lower limit value of $v_{1}$ and upper limit value of $v_{2}$ were determined as 2.5 and 2.9 m/s with a prospective minimum arcing time of 7 ms.

Transient Current Interruption Characteristics of a Novel Mechanical DC Circuit Breaker

With the rapid development of multiterminal direct current (MTDC) grids, high-voltage direct current circuit breakers (HV-DCCB) capable of interrupting currents within 5 ms are in urgent demand. The mechanical DCCB has always been one of the main proposals for HV-DCCBs. The current commutation is the prerequisite for mechanical DCCBs to interrupt currents successfully. Focused on the current commutation difficulty, a novel mechanical DCCB has been investigated in this paper. A simulation model of the novel mechanical DCCB in MTDC system for fault current interruption was established in PSCAD. By analyzing the simulation results, the detailed transient varying patterns of current, voltage, and energy in the novel mechanical DCCB during its interruption process are revealed. To verify the feasibility of the novel mechanical DCCB, a prototype was developed in the lab, and current interruption tests were carried out on the prototype. Experimental results have shown that a current of 5.3 kA can be interrupted by the prototype within 3 ms. In the end, failures that occurred in initial experiments are discussed and relative protection measures have been proposed. By adopting these measures, failures are successfully avoided and the normal operation of the novel mechanical DCCB are ensured.

Dielectric Recovery Characteristics after High‐Frequency Current Interruption in Vacuum Circuit Breaker

SUMMARYWhen the contacts of circuit breaker are opened just before current zero, the gap between contacts will still be very short. Therefore, it cannot withstand recovery voltage between the contacts. In such a case, multiple reignition is likely to take place. Many investigators had tried to clarify this phenomenon, and many reports have been published. However, high‐frequency current interruption and dielectric recovery characteristics are related to some parameters (value of current, arc time, and so on). In addition, arc phenomenon has also been implicated. Hence, it is difficult to understand this phenomenon accurately. In this paper, we conducted dielectric recovery test and high‐frequency current interruption test. Further, we conducted observation experiment using vacuum chamber in order to investigate the effect of small dc current. At the end, we calculated plasma density in the electrodes after high‐frequency current interruption by considering the result of observation experiment and dielectric recovery test.

An Improved Empirical Fuel Cell Polarization Curve Model Based on Review Analysis

Based on a review analysis of empirical fuel cell polarization curve models in the literature, an improved model that can predict fuel cell performance with only measured current-voltage data is developed. The fitting characteristics of this new model are validated by fitting bench test data and road test data. In the case of bench test data, a comparison of the new model and two representative models is conducted, and the results show that the new model presents the best fitting effects over a whole range of current densities. Moreover, the fitted ohmic resistances derived from the new model show good agreement with the measured values obtained through a current interruption test. In the case of using road test data, the new model also presents excellent fitting characteristics and convenience for application. It is the author’s belief that the new model is beneficial for the application-oriented research of fuel cells due to its prominent features, such as conciseness, flexibility, and high accuracy.

A Novel Vacuum Interrupter Contact Design for Improved High Current Interruption Performance Based on a Double-TMF Arc Control System

A new two-contact system with double-transversal magnetic field (TMF) structure is investigated regarding its potential for high current interruption. It consists of two concentric TMF contacts, in which the inner contact has a disk-shaped structure (spiral contact) and the outer contact a cup-shaped structure. This contact assembly gives several advantages over the use of single-TMF contacts, as the constricted high-current arc might either split between both inner and outer contacts or commute from the inner to the outer contact and continue its rotation. In both scenarios, we expect a better distribution of the arc energy over a larger contact surface. B-field simulation and Lorentz force calculation are carried out to investigate whether two constricted arcs, with one burning on the inner contact and the other on the outer contact, can coexist given their mutual attraction. Single-phase high current interruption tests were carried out to compare the performance of this new double-TMF contact system with that of a standard spiral-type single-TMF one. These tests have revealed superior performance of the new double-TMF contact system, which could interrupt current amplitude at least 20% higher than the one interrupted by the single-TMF contact system.

Current Interruption in Air for a Medium-Voltage Load Break Switch

The current interrupting capability of a load break switch (LBS) depends on many design parameters, such as contact and nozzle geometry, contact movement, and gas flow. For developing more compact gas blow LBSs for air, it is necessary to find design recommendations where each parameter is addressed individually. In this paper, a current interruption test switch is built for this purpose. The interruption tests are conducted with a directly powered high-voltage circuit. The result shows the minimum gas flow required for current interruption for various basic nozzle geometries and at different contact positions. The study is particular relevant for the 24 kV/630 A class, and it is shown that 0.3 bar upstream pressure appears to be a threshold value for successful interruption. Some conclusions are also applicable for other medium-voltage ratings. An LBS should be designed so that at least one current zero crossing comes outside the nozzle when the switch is still blowing with full strength.

Influence of Numerous Current Interruptions on &lt;i&gt;V-t&lt;/i&gt; Characteristics of a Vacuum Interrupter

The insulation strength of a vacuum interrupter is investigated before and after dozens of large current interruptions. The breakdown voltage decreases from 119.5kV to 103.2kV by the current interruption test.

New testing method for the classification of contact materials for vacuum circuit breakers

A new testing method to classify contact materials for high-current interruption with vacuum circuit breakers (VCB) is described. The testing effort is reduced by diminishing the contact gap and the contact area as well as by an adequate testing circuit. Consequently, the number of experiments can be increased for the benefit of a high statistical certainty in the classification of contact materials. The test results are in good agreement with the results of full-size short-circuit current interruption tests carried out in a high-power testing laboratory with VCB equipped with contact materials classified in the new testing circuit.