Interruption Capacity Research Articles

Spatiotemporal evolution of electrical conductivity in current-limiting-fuse arc

To improve the interruption capacity of a current-limiting fuse, a detailed diagnosis of the spatial electrical conductivity distribution inside the fuse arc under the current limiting phase around current zero is required, because this distribution determines the distribution of transient recovery voltage inside the fuse. However, well-established methodologies applicable to fuse arcs are lacking, so the spatial distribution remains unknown. This study presents a borescope-integrated spectroscopic system that simultaneously obtains single-shot recordings of the axial distributions of the electron density and arc temperature in the fuse arc just before extinction. Combining the electron densities and arc temperatures, we can identify the fuse arc composition and hence calculate the axial electrical conductivity distribution under the first Chapman–Enskog approximation. The electrical conductivity provided by this systematic methodology includes no large uncertainties, thus demonstrating its superiority against previous estimation methods of the electrical conductivity.

DC Arc Quenching Using Ablation of Polymer Narrow‐Section Arranged around Fuse Element

This paper was arranged a polymer cylinder around a Cu fuse‐element to increase both an arc resistance during a DC arc quenching process and an insulation resistance after the DC arc quenching. The used polymer cylinder equips a narrow‐section with a width made from the polymer. A position of the narrow‐section was around an arc‐ignition point of the Cu fuse‐element. Silica‐sand (SiO2‐sand) was filled inside the polymer cylinder. Then, a damping DC with a prospective peak of 1000 A was energized to the Cu fuse‐element. As an experimental result, was successfully increased with of the narrow‐section. In addition, the rise in of the narrow‐section also increased to more than 10 under the DC 1000 V application after the arc quenching. In order to interpret rise and high under the polymer cylinder arrangement, chemical composition, an electrical resistivity , and a thermal diffusivity of Cu/SiO2/Polymer vapor mixture was also calculated. Based on the experimental result and calculation result, rise can be interpreted based on rise in and due to the polymer vapor admixing into Cu/SiO2 vapor mixture. In addition, increasing can also be interpreted by the polymer ablation of the narrow‐section of the cylinder. The results are useful to further increase the interruption capacity of the DC fuse. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Flexible Fault Current Adaptation Features of a Novel DC Circuit Breaker Assisted by Superconducting Fault Current Limiters

The high d <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</i> /d <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> before zero-crossings easily leads to delayed or failed operations for the active current injection mechanical DC circuit breaker, especially for small direct current interruptions. The pre-charging process also makes this type of circuit breaker hard to realize repeat operations economically in the high voltage DC system. This paper proposes a novel DC circuit breaker and its design method that deeply coordinating a superconducting fault current limiter with the active current injection DC circuit breaker. This method significantly reduces d <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</i> /d <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> before current zero-crossings and enables repeat operations economically. Besides limiting fault currents, the superconducting fault current limiter also charges the resonance capacitor flexibly in the circuit breaker, realizing the injected reverse current keep a constant proportion to the arbitrary fault current. Validations of the flexible capacitor charge and repeat operations are made by simulation and low voltage experiments. The charging times are within 2.5 ms and the reverse current keeps 1.2 to 1.7 times over the fault current under arbitrary conditions. D <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</i> /d <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> at current zero is reduced by 80% under 30% of rated interruption capacity. Flexible capacitor charge experiments are consistent with the simulation design. The superconducting tapes can recover within 300 ms to support repeat operations.

GPU-Accelerated Online Short-Circuit Interrupting Capacity Scan Based on Unified Modeling

With the increasing of transmission density and short-circuit current level, interruption capacity scanning has become an important approach for the online assessment of the circuit breaker. The short-circuit calculation scale and the expected failures significantly increase under the demand of unified analysis of the whole grid, which cause the considerable challenges for online assessment. In this study, we propose a GPU-accelerated short-circuit interruption capacity scanning algorithm for two different unified models, that is, GPU-based 2D and 3D expansion models. For both models, the redundant configuration of the fault network matrices is designed to reduce the cost of GPU computation process. Then, the batch node voltage analysis and the batch branch current calculation are derived using the considered model. In addition, the differences between two models are discussed in detail. Simulations show that the proposed algorithm with GPU-based 3D-expand model has a 3.45× speedup compared with the traditional algorithm on a 9241-bus system with 8-core CPU. Therefore, the proposed algorithms have the potential to handle the full short-circuit current scan under the unified analysis scenario.

Study of vacuum arc plasma transport characteristics during the DC interrupting process

The mechanical DC vacuum circuit breaker based on forced-over-zero technology will inevitably generate vacuum arc during the actual interrupting process. Since the current drop frequency is usually very high, the vacuum arc usually exhibits obvious transient characteristics, and the excessive transient characteristics may even become a key factor limiting the interruption capacity. In order to improve the mechanical DC vacuum circuit breaker arc interrupting capability, this paper establishes a vacuum arc transient magneto-hydrodynamic simulation model in the DC interrupting process and studies the plasma transport characteristics of the vacuum arc under different DC interrupting conditions. The results show that the ion pressure, ion density and ion temperature decrease with decreasing arc current, while the ion velocity gradually increases during the DC interrupting process. The increase in breaking current and current drop frequency will increase the ion density in the arc column at the moment of current crossing zero, resulting in more difficult vacuum arc interrupting. The results of the study can provide an important theoretical basis for a deeper understanding of the vacuum arc transient process in the DC interrupting process and improve the DC vacuum circuit breaker arc interruption capability.

Vacuum arc characteristics of a new type of curved-surface contact for high-frequency forced interruption in aero applications

Aiming at the arc interruption problem in aviation 270 V DC power systems, this report proposed new contact types of vacuum interrupter contacts with curved surfaces for high-frequency forced interruption. The characteristics of vacuum arc behavior, high-frequency forced interruption capacity and contact surface ablation under curved contact with different structural parameters are investigated. The interruption ability, arc voltage characteristics and contact ablation of CuW80 and CuCr25 contact materials and their differential combinations were obtained. To select the optimal structural parameters of the curved contacts, a method based on the curvature of the electrode surface was proposed for high-frequency forced interruption under a short-gap vacuum arc. Experimental results show that a current of 4.8 kA can be interrupted at a commutation frequency of 20 kHz with a di/dt of 650 A/μs when the curvature of curved contacts is in a certain range.

Developing an electrical power system of a mobile electron beam accelerator to treat wastewater and industrial effluents / Desenvolvimento de um sistema de energia elétrica de um acelerador móvel de feixe de elétrons para tratar águas residuais e efluentes industriais

The treatment of wastewater and industrial effluents by electron beam irradiation is a promising technique, however, not very widespread in Brazilian territory. The design and construction of a mobile unit by the Nuclear and Energy Research Institute, containing an electron beam accelerator of 700 keV and 20 kW is innovative to demonstrate the effects and positive results of this technology. The aim is to transfer the mobile unit to several companies with interest in liquid waste treatment, connect to the industry electrical system and start the ionization treatment process through electron beam. The mobile unit connection to the local electrical system may be a challenge due to the great diversity of voltages and distances involved, as well as the large injections of harmonic content generated by the electron beam accelerator that can affect sensitive loads in the industrial system. In this work, an analysis of the electrical power system of the mobile unit was made, regarding the interruption capacity, selectivity protection and adequate short circuit levels, in order to assure a greater reliability in the operation. At the end, the control panel of the mobile unit, simulations and measurements were carried out at the 1.5 MeV and 37.5 kW electron beam accelerator, installed in the Radiation Technology Center, demonstrating the necessity of applying a filter to reduce the measured harmonic distortion. The analysis of the mobile unit electrical power system was made, in order to assure a greater reliability in the operation.

Influence of Electrode Configurations on the Interruption Capacity of Laser Triggered Vacuum Switch

The electrode configurations have an important effect on the interruption performances of laser triggered vacuum switch (LTVS), but few works pay attention to it so far. The objective of this article is to study the interruption capacity of LTVS with different electrode configurations. The 3-D simulation models of axial magnetic field (AMF) electrode and transverse magnetic field (TMF) electrode are built up, and the magnetic field distributions are calculated and compared. The test platform is set up based on a detachable vacuum chamber. The interruption capacity of LTVS with different electrode structures, electrode spacings, and polarity configurations is studied and analyzed. The test results prove that, compared to the AMF electrode, the interruption capacity of LTVS under the TMF electrode is obviously better, but it is more susceptible to the electrode spacing, and gradually decreases with the increase of electrode spacing. Influence of polarity configuration on the interruption capacity of LTVS is closely related to the target material. The LTVS with KCl + Ti under the positive polarity configuration shows better interruption capacity than negative polarity configuration. The works in this article provide references for the design of LTVS products.

Multi-User Concurrent Job Scheduling Method of Network Analysis Application Based on CPU/GPU Cluster

Multi-channel multi-core CPU parallel and CPU+GPU heterogeneous parallel are effective means to enhance Network Analysis Application computing. To solve the job scheduling problem of Network Analysis Application with multi-level dispatching, multi-user, multi-task in CPU/GPU heterogeneous cluster environment, a multi-user concurrent job scheduling method for Network Analysis Application in CPU/GPU cluster is proposed. According to the characteristics of Network Analysis Application, it is suggested that state estimation and dispatcher power flow should be accelerated in parallel with CPU, while static security analysis, perturbation power flow calculation and interruption capacity scanning should be accelerated in parallel with CPU+GPU. The job scheduling method proposed in this paper can satisfy the high concurrent requests of multi-level Dispatching & Control Center in the isomorphic and heterogeneous computing environments.

Analysis of alternative parameters of dynamic resistance measurement in high voltage circuit breakers

Throughout its lifetime, high-voltage circuit breaker (HVCB) contacts suffer from inevitable degradation processes, especially during the formation of electric arcs. Highly degraded contacts can reduce the current interruption capacity and increase the chances of operational faults, which might lead to considerable financial losses. Therefore, the use of efficient evaluating techniques is a key factor to achieve systems reliability. The dynamic resistance measurement (DRM) is a technique that can be used to evaluate the degradation level of HVCB' contacts. It stands out from the usual technique, static resistance measurement, by allowing the assessment of both the main contacts and the arcing contacts (ACs). Usually, the mean resistance or the area under the DRM curve is used to estimate the AC degradation. However, DRM is a non-standardised technique and there are no specified parameters to evaluate the real wear conditions. Therefore, an analysis of alternative parameters extractible from the DRM technique is presented in this study, such as amplitude and variance of the DRM curve. The results attest the possible use of more than one parameter for the continuous evaluation of HVCB ACs, characterising the DRM as a more complete and precise diagnosis tool.

An Adaptive Reclosing Strategy for MMC-HVDC Systems With Hybrid DC Circuit Breakers

Modular multilevel converter (MMC) based high voltage direct current transmission (HVDC) is an effective solution for large-scale renewable power integration over long-distance. In the overhead MMC-HVDC systems, the high voltage DC circuit breakers (DCCB) are implemented to interrupt the DC fault current. Subsequent to fault isolation, the DCCBs are required to automatically re-close to restore power transmission quickly. However, when the DCCBs are re-closed to permanent faults, they will be tripped again, resulting in a high requirement of interruption capacity for DCCBs and second overcurrent strikes on the HVDC systems. To overcome the drawbacks of the conventional auto-reclosing scheme, this paper proposes an adaptive reclosing scheme based on the active pulse injection from the converter associated with the coordination control of hybrid DCCBs. The single-end adaptive reclosing scheme as well as the two ends adaptive reclosing scheme dedicated to two-terminal HVDC systems and meshed DC grids are presented respectively. By applying this method, the location of faults can also be achieved in the case of permanent faults. In order to verify the effectiveness of the proposed adaptive reclosing schemes, extensive simulations have been conducted under PSCAD/EMTDC.

Interruption of Low-Voltage DC Arc in Air Under Axial Magnetic Field

This paper represents the findings from our research in which a series of experiments were conducted on dc current interruption in air in axial magnetic field provided from rare earth magnets mounted in the test electrodes. The experimental range was as follows: arc voltage 80–100 V, arc length 5–10 mm, arc current 80–800 A, and applied field 35–2400 G. The free-burning arc diameter was measured in these experiments from high-speed photographs. It was found that a strong magnetic field can improve the interruption capacity of air-arc significantly. In the experiments, the successful switching time of both 220 and 330 A free-burning air-arc in 2.4 kG was less than half of the successful switching time of corresponding free-burning arcs in air. For higher current arcs, the outcome was more encouraging. An 800 A free-burning arc sustained for about 48 ms, whereas a 315 G field interrupted it within 8 ms. The information found on arc-root diameter and current density of 80–800 A free-burning arcs in air has filled a gap of data found in the literature. This information, in turn, will help to improve the theories available on free-burning arcs.

A Thyristor Full-Bridge-Based DC Circuit Breaker

DC circuit breakers (DCCBs) are vital for the safe and continuous operation of large high-voltage dc grids. Insulated-gate bipolar transistor-based hybrid DCCBs (IHCBs) can interrupt currents quickly and have good operational characteristics. Thyristor-based hybrid DCCBs (THCBs) are superior to IHCBs in terms of interruption capacity because of the large surge current capacity of thyristors. Nevertheless, existing THCBs have limitations regarding one or more of the following characteristics: pre-activation, fast reclosing, quick interruption of small current and no requirement for an additional pre-charge source. This paper proposes a thyristor full-bridge-based dc circuit breaker (TFCB) with all favorable characteristics mentioned above. The TFCB contains a main conductor, a main breaker (MB), an auxiliary branch, and an energy absorber. After an interruption, the capacitor in the TFCB can restore its initial voltage quickly to guarantee that the TFCB is available for the next interruption. Quick interruption of small currents is achieved using the additional charge current provided by the auxiliary branch. Pre-activation is achieved using the conduction path in the MB. The parameter designs are analyzed to ensure that the TFCB reliably interrupts currents without damaging itself. The proposed TFCB is validated using prototype experiments and PSCAD/EMTDC simulations.

Enhanced Fault Current-Limiting Circuit Design for a DC Fault in a Modular Multilevel Converter-Based High-Voltage Direct Current System

The main weakness of the half-bridge modular multilevel converter-based high-voltage direct current (MMC-HVDC) system lies in its immature solution to extremely high current under direct current (DC) line fault. The development of the direct current circuit breaker (DCCB) remains constrained in terms of interruption capacity and operation speed. Therefore, it is essential to limit fault current in the MMC-HVDC system. An enhanced fault current-limiting circuit (EFCLC) is proposed on the basis of fault current study to restrict fault current under DC pole-to-pole fault. Specifically, the EFCLC consists of fault current-limiting inductance L F C L and energy dissipation resistance R F C L in parallel with surge arrestor. L F C L reduces the fault current rising speed, together with arm inductance and smoothing reactor. However, in contrast to arm inductance and smoothing reactor, L F C L will be bypassed via parallel-connected thyristors after blocking converter to prevent the effect on fault interruption speed. R F C L shares the stress on energy absorption device (metal oxide arrester) to facilitate fault interruption. The DCCB requirement in interruption capacity and breaking speed can be satisfied effortlessly through the EFCLC. The working principle and parameter determination of the EFCLC are presented in detail, and its effectiveness is verified by simulation in RT-LAB and MATLAB software platforms.

6-in Dual-Gate Ring Commutated Thyristor for DC Circuit Breakers

DC circuit breakers (DCBs) are crucial components in dc power systems. The ultralow operating frequency of the DCBs enables the use of gate-commutated thyristors (GCTs) in the DCBs. This paper proposed a 6-in dual-gate ring commutated thyristor (DGRCT) for the DCB applications. The wafer and package designs of the DGRCT are first presented and discussed, analyzing the principles of the current commutation in the DGRCTs. Subsequently, a DGRCT prototype is fabricated, and experiments are conducted to measure the inductance along the current commutation loop (CCL) of the prototype DGRCT. Finally, a large current interruption experiment is conducted. The results show that the prototype DGRCT reduced the parasitic inductance within the CCL by at least 20% compared to conventional GCTs with single-gate ring design. The maximum current interruption capacity of the prototype DGRCT is no less than 12 kA at T = 300 K, which approaches the fault current interruption requirement in DCB applications for both transmission and distribution levels of dc power systems.

DC Interrupting With Self-Excited Oscillation Based on the Superconducting Current-Limiting Technology

A dc circuit breaker (DCCB), which combines a superconducting current-limiting technology and a self-excited oscillation interrupting technology, was proposed. The proposed DCCB includes a superconducting current-limiting module and an interrupter module. The objective of this paper is to investigate the effects of a transverse magnetic field (TMF) on dc interruption based on the self-excited oscillation principle. The dc interruption characteristics of CO2 and SF6 were investigated by applying a TMF of 0 and 200 mT with a puffer-type structure as a benchmark. The experimental results show that applying a TMF of 200 mT can significantly reduce the arcing time compared with a TMF of 0 mT and puffer-type structure. The dc interruption capacity for the SF6 insulation is higher than that for the CO2 insulation in the interrupter module under the same experimental condition. The simulation results of rated voltage of 10 kV show that the superconducting current-limit module limited the short current of 20 kA to less than 1 kA, and the arcing time was 4.5 ms. The results of rated voltage of 200 kV, short current of 30 kA, show that the DCCB only needed to interrupt the limited current of 3.5 kA and the overvoltage was less than 200 kV.

Dynamic Dielectric Recovery Synergy of Hybrid Circuit Breaker With CO2 Gas and Vacuum Interrupters in Series

This paper investigates the dynamic dielectric recovery synergy (DDRS) of hybrid circuit breakers (HCBs) with CO2 gas and vacuum gaps in series. The interaction between the vacuum arc and CO2 gas arc is simulated by the continuous transient arc model and Mayr arc model. The simulation results indicate that the extra methods, for example, dividing capacitors, are needed to obtain optimal DDRS of HCB. The prototype of HCB and the test circuit are established. The influence of the coordination of arcing time, dividing capacitors, and the CO2 gas pressures on the transient recovery voltage (TRV) distribution and the breaking capacity is investigated. The differences of HCBs with SF6 gas and CO2 gas are also compared. According to the results, favorable DDRS in HCB can be obtained in the condition that the vacuum gap endures the initial TRV while the following major TRV distribution is mainly depended on the dynamic dielectric in CO2 gas gap. However, the dynamic dielectric recovery of CO2 gas gap is limited by the structure of rotating arc CO2 gas interrupter in this paper. In the future, the interruption capacity of HCB based on CO2 gas can be improved by synergy control, as the development of CO2 gas circuit breakers.

Experimental Investigation of High-Current Vacuum Arc Instability Modes Under Transverse Magnetic Field

The behavior of vacuum arc influences the heat distribution on the contacts and the contact melt and erosion, and thus, it greatly affects the breaking capacity after current zero. In this paper, high-current arc instability modes were investigated in a demountable vacuum chamber with a high-speed charge-coupled device video camera. Three kinds of spiral contacts were used with CuCr50 as the contact material. We observed and summarized three types of arc instability modes: 1) multicolumn arc mode; 2) single stationary jet mode; and 3) single moving jet mode. As the peak current increases, the instability mode will transition from multicolumn arc mode to single stationary jet mode, and then to single moving jet mode. We also found the periodical transition between the plasma jet and the relatively diffuse columnar arc during single moving jet mode. It was shown that the occurrence of arc instability modes, especially the single moving jet mode, is usually accompanied by the increase in mean value and high fluctuations on the arc voltage. Besides, during the instability mode, a large number of droplets and macroparticles will be produced in the gap. These will have a great influence on the interruption capacity of the vacuum interrupter.

Application of SFCL on Bus Tie for Parallel Operation of Power Main Transformers in a Fuel Cell Power Systems

In the power plant using high temperature fuel cells such as Molten Carbonate Fuel Cell(MCFC), and Solid Oxide Fuel Cell(SOFC), the generated electric power per area of power generation facilities is much higher than any other renewable energy sources. - High temperature fuel cell systems are capable of operating at MW rated power output. - It also has a feature that is short for length of the line for connecting the interior of the generation facilities. In normal condition, these points are advantages for voltage drops or power losses. However, in abnormal condition such as fault occurrence in electrical system, the fault currents are increased, because of the small impedance of the short length of power cable. Commonly, to minimize the thermal-mechanical stresses on the stack and increase the systems reliability, we divided the power plant configuration to several banks for parallel operation. However, when a fault occurs in the parallel operation system of power main transformer, the fault currents might exceed the interruption capacity of protective devices. In fact, although the internal voltage level of the fuel cell power plant is the voltage level of distribution systems, we should install the circuit breakers for transmission systems due to fault current. To resolve these problems, the SFCL has been studied as one of the noticeable devices. Therefore, we analyzed the effect of application of the SFCL on bus tie in a fuel cell power plants system using PSCAD/EMTDC.

Decay Modes of Anode Surface Temperature After Current Zero in Vacuum Arcs—Part II: Theoretical Study of Dielectric Recovery Strength

Anode surface temperature after current zero has a great impact on the interruption capacity of a vacuum interrupter. The objective of this paper is to theoretically investigate the relation between breakdown voltages and anode surface temperature after current zero. A heat conduction model was adopted to describe the temperature development of the anode, taking account of phase transition and evaporation. The breakdown voltages in certain metal vapor densities were obtained by the Particle-in-Cell/Monte Carlo collision (PIC-MCC) method. Finally, the Paschen curve for copper vapor was obtained using the PIC–MCC method and verified by the theoretical model. Moreover, the minimum breakdown voltage, 30 V, was obtained at a density of $1.3\times 10^{22}/\text{m}^{3}$ with a gap of 10 mm, which corresponded to a surface temperature of 1983 K. In order to ensure a successful interruption, anode surface temperature should not be higher than 1983 K at current zero, and the melting time should be kept as short as possible.