Breaking Capacity Research Articles

Study on cathode spot expansion process in vacuum arc with high di/dt

The study on cathode spot under high di/dt condition promotes the application of vacuum circuit breaker in DC transmission and aerospace technology. Cathode spot, as a source of microscopic particles, directly affects the breaking capacity of vacuum circuit breaker. In this paper, vacuum arc with high di/dt was generated in L-C oscillating circuit. The cathode spot behavior was obtained by a high-speed camera. There are two types of cathode spots with different size, different expansion velocity and brightness. The difference in the size of different types of cathode spots leads to the difference in the thermal diffusion velocity of the spots, which is also the main reason for the difference in the expansion velocity of the two types of spots. The influence of spot current density on temperature and electric field is discussed. With the increase of di/dt, the phenomenon of unstable expansion of cathode spots is observed. A new cathode spot is generated in the cold electrode area far away from the previous cathode spot area, resulting in a significant increase in the arc voltage. The expansion characteristics of cathode spot under different current amplitude, frequency and di/dt conditions are obtained.

The Design and Development of a Novel 10 kV/60 kA Hybrid DC Circuit Breaker Based on Mixed Solid-State Switches

Hybrid DC circuit breakers (HDCCBs) have excellent performance in terms of breaking speed and low losses and have become the mainstream technology for dc fault isolation in dc grids. However, because of the breaking limitation of the solid-state branch in HdcCBs, the existing HdcCBs are still weak in breaking high current. Although the breaking ability can be improved by series and parallel devices, the cost will increase rapidly, and it is very difficult to share current by paralleling a single type of device. This article proposes a novel HdcCB topology that combines two types of power electronic devices in solid-state branches to meet the requirement of a large breaking capacity in dc grids. The structure and breaking principles of this novel topology, which aims to break high current, are introduced. The design methods of the key parameters are presented. Then, the current breaking ability of the novel topology is verified by developing a prototype completing a 10 kV/60 kA breaking test in 3 ms. Finally, this novel topology is compared with other dc circuit breakers at the same breaking level, which shows that this novel topology has obvious advantages in cost and volume with fewer devices.

The Structural and Electromagnetic Comparative Analysis of the Bifilar-Meander-Type Winding Method of Superconducting DC Circuit Breaker

As the utilization of DC systems increases worldwide, the importance of DC cutoff technology is increasing. We proposed a hybrid DC cutoff technology combining an SFCL (superconducting fault-current-limiter) and a mechanical DC circuit breaker. This model can perform a fault-current-limiting operation through the quenching of the SFCL and a breaking operation through an artificial cutoff zero point of a mechanical DC circuit breaker. In particular, the SFCL is responsible for the growth of the initial fault current according to the DC characteristics. As the DC system’s supply and demand increase, the DC system’s capacity also increases. Therefore, the fault-current-limiting capability of the SFCL should be increased according to the increasing DC system breaking capacity. The fault-current-limiting capability can be increased by increasing the superconducting wires used in the SFCL. Current commercially available SFCLs use bifilar-helical-type and bifilar-spiral-type winding methods. These have the disadvantage of increased volume with increased capacity. To compensate for these disadvantages, we proposed a bifilar-meander-type winding method. In this paper, a new bifilar-meander-type winding method was introduced. In addition, the structural and electromagnetic parts of the existing winding method and the bifilar-meander-type winding method were compared and analyzed for differences. The program used for this analysis is the electromagnetic analysis Maxwell program. As a result, it was confirmed that the bifilar-meander-type winding method is superior to the conventional bifilar-helical and bifilar-spiral types.

Coordinated DC Interruption Method Based on Magnetic Coupling Current-Limiting and Dissipation

A flexible dc grid is important for supporting large-scale new energy integrations. To ensure the stable operation of the dc grid, a dc circuit breaker (DCCB) is needed for fault isolation. At present, the cost of DCCBs is high, and the breaking capacity is limited. This limitation can be effectively solved through the coordination of fault current limiters (FCLs) and DCCBs. In this article, a coordinated interruption topology of an magnetic coupling FCL (MCFCL) and hybrid DCCB is proposed. A coordinated interruption strategy based on magnetic coupling current-limiting and energy dissipation is proposed to improve the dynamic performance of the FCL and reduce the energy dissipation and breaking time of the DCCB. A two-stage mathematical model of coordinated interruption is established, and its control principle is analyzed. Furthermore, the influence of the inductance and resistance of the MCFCL secondary side, coupling coefficient and rated voltage of the arrester on the coordinated interrupting process is researched. On this basis, parameter optimization and economic analysis are carried out. Finally, a scaled test for the coordinated interruption of the DCCB and MCFCL was carried out, which verifies the feasibility of the coordinated interruption strategy based on magnetic coupling current-limiting and energy dissipation.

Quenched Flux-Coupling Superconducting Fault Current Limiter Scheme and Its Electromagnetic Design Method.

In order to solve the problem of excessive short-circuit current in the present power system, a fault current limiter has become a new type of power device with high demand and is one of the current research hotspots. The flux-coupling type superconducting fault current limiter (FC-SFCL) generates a current-limiting impedance through decoupling superconducting parallel inductance based on the circuit breakers' fractional interruption. The principle is simple, and the impedance is low during normal operation. It can directly use the existing circuit breaker to open a short circuit that is much higher than its own breaking capacity. Thus, it can be used for large-capacity fault current limiting and effective failure breaking. This paper focused on exploring and studying the implementation scheme of practical products of FC-SFCL. Considering that the quenched-type parallel inductance can limit the first peak value of the fault current, a quenched-type improvement scheme was proposed. Then, an electromagnetic design method based on the simplified calculation of the number of parallel tapes was proposed, which simplified the design process and reduced the design difficulty of the quenched FC-SFCL. Taking a 10 kV/500 A/5 kA quenched prototype as an example, its electromagnetic design was completed, and the performances of the non-quenched and quenched schemes were compared. The results showed that, compared to the non-quenched structure, the technical economics of the quenched one were more prominent, and it can be used preferentially for engineering prototypes. This study about the scheme of the quenched FC-SFCL and its electromagnetic design method is useful for promoting the implementation of the current limiter engineering prototype.

Magneto-hydrodynamic simulation study of direct current multi-contact circuit breaker for equalizing breaking arc

This work is based on a direct current (DC) natural current commutation topology, which uses load-carrying branch contacts carrying rated current and multiple sets of series arcing branch contacts in parallel to achieve circuit breaking. The proposed topology can meet the new requirements of higher voltage DC switches in aviation, aerospace, energy and other fields. First, a magneto-hydrodynamic arc model is built using COMSOL Multiphysics, and the different arc breaking characteristics of the arcing branch contacts in different gas environments are simulated. Then, a voltage uniformity coefficient is used to measure the voltage sharing effect in the process of dynamic interruption. In order to solve the dispersion of arcing contact action, a structural control method is adopted to improve the voltage uniformity coefficient. The uniform voltage distribution can improve the breaking capacity and electrical life of the series connection structure.

Analysis of Breaking Capacity Calculation on Busbar Room Panel at PT Trias Indra Saputra

The electric panel has a function as a distribution device and as protection for electricity from the PLN. A panel must at least have protective equipment that functions so that if a fault occurs in electrical equipment, the fault can be corrected and does not interfere with the performance of the panel. In order for the protection equipment to work properly, accuracy is required in selecting the current rating and breaking capacity value of the protection components used. The purpose of this research is to analyze the breaking capacity value, nominal load current value, and short circuit current for each electrical protection component in the busbar room panel at PT Trias Indra Saputra. The analysis was carried out by comparing the results of manual calculations with calculations using the XL3-Pro calcul software, as well as the installed protection components. After calculating and comparing the results, the electrical protection components are still suitable for use as protection in the event of a fault, both short circuit fault and overcurrent on the electrical equipment in the busbar room panel at PT Trias Indra Saputra. In the outgoing protection Q0 is a protection component that connects the power source from the LVMDP panel to the busbar room panel at PT Trias Indra Saputra. Different results were obtained from the three comparisons. By using the MCCB current rating of 100A, it has been able to secure the circuit from short circuit faults and overload

Analysis of the fleet and evaluation of the switching resource of 10 kv switches of the branch of pjsc «Rosseti Center»-«Orelenergo»

THE PURPOSE. Analysis of the fleet and evaluation of the switching resource of 10 kV switches of the branch of PJSC «Rosseti Center»-«Orelenergo». METHODS. In the work, based on the database of the branch of PJSC «Rosseti Center»-«Orelenergo», an analysis of the fleet of 10 kV high-voltage switches was carried out, the types of switches used, their shares in the fleet of switches were identified. The park of circuit breakers was investigated according to technical characteristics, including rated currents and currents of maximum breaking capacity in accordance with GOST R 52565-2006 and GOST 687-78, as well as the current standards of the technical organization of PJSC «Rosseti». RESULTS. In the course of the study, it was revealed that the fleet of 10 kV switches installed in switchgear substations with a higher voltage of 35-110 kV of the branch of PJSC «Rosseti Center»-«Orelenergo» is represented by 1833 switching devices, among which: 1197 switches with low-oil arc extinguishing chambers, 636 switches with vacuum, which is, respectively, 65% and 35% of the park. At the same time, 1009 switching devices have a rated current of 630 A, and 366 switching devices – 1000 A, 1526 pieces of equipment have a rated cut-off current of 20 kA. A comparison of a low-oil switch of the VMP type and a vacuum switch BBB with a modern vacuum switch of the BB/TEL series from the point of view of the switching resource in order to justify its use to replace these switches on specific power lines. CONCLUSIONS. Identification of the parameters of the 10 kV circuit breaker fleet makes it possible to develop rational plans for equipment replacement. Analysis of the switching resource of different types of switches allows you to choose equipment with the best characteristics.

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.

Vacuum arc characteristics of an AMF–TMF composite contact with fixed AMF contacts under different opening velocities

The objective of this paper is to determine the vacuum arc characteristics of a novel axial magnetic field (AMF)–transverse magnetic field (TMF) composite contact under different opening velocities. The AMF–TMF composite contact consists of a pair of outer fixed AMF contacts and a pair of inner movable TMF contacts. Drawn arc experiments were carried out in an L–C discharging circuit with this composite contact system to observe the differences in the arc development process under different opening velocities. The opening velocity of the inner movable contact was set to 1.3, 1.8, and 2.3 m/s. The arc current was up to 20 kA rms. In the experiments, the arc behavior was recorded using a high-speed camera. The arc current of each contact and the arc voltage were measured. Then the arc characteristics, including the arc current transfer characteristics, diffused arc duration, and mental droplet distribution before zero current, were quantitatively analyzed. Furthermore, magnetic field calculation was carried out to explain why the arc characteristics are different under different opening velocities. Experimental results show that with an increase in the opening velocity from 1.3 to 2.3 m/s, the diffused arc duration before zero current increases from 1.05 to 1.75 ms when the cathode is on the fixed side and increases from 1.30 to 1.90 ms when the anode is on the fixed side. In addition, the quantity of mental droplets between contacts before zero current is less with high opening velocity. It indicates stronger short-current breaking capacity under higher opening velocity. From the simulation results, it can be seen that during the arcing period, more current transfers to the fixed AMF contact under higher opening velocity and generates a stronger AMF. It could explain the earlier diffusion of the vacuum arc column under higher opening velocity.

Dynamic characteristics of cathode spots during expansion process in a vacuum arc

Cathode spot is the source of plasma and metal vapor which affects the breaking capacity of vacuum circuit breakers. In this paper, the cup-shaped axial magnetic field contacts were used and the images of cathode spots were obtained by an ultra high-speed camera in the experiment. The dynamic characteristics of cathode spots during expansion process in vacuum arc were investigated. Under the conditions of different current amplitudes, different distributions of cathode spots were observed. During the expansion process of cathode spot, there are group spots and individual spots. The group spot only occurs in the cold electrode. The electrons emission characteristics of cathode spot as a function of temperature and electric field was calculated. The formation of group spot is related to the current and electron emission of cathode spot. The cathode spots were identified by Matlab. It was found that the variation of number of cathode spots is consistent with the current. However, at different stages, the reasons for the increase in the number of cathode spots are different, such as the increase in the area of cathode spots in the initial arcing stage and the splitting of cathode spot. It was observed that the cathode spots are not completely evenly distributed on the cathode surface. The farther away from the center of the contact, the longer the distance between the cathode spots. It is mainly effected by the transverse magnetic field (TMF) which is generated by the arc column. The closer to the contact edge, the higher the TMF at the cathode spot and the higher the expansion velocity of cathode spot.

Improved Recovery Time and Voltage Stability for Resistive Superconductor Fault Current Limiters

Fault current levels occurring in power systems force the breaking capacities of the breakers. In the power system elements, the generator, transformer, cables, etc., are exposed to the dangerous effects of fault current until the breaker clears the fault. Various limiting methods have been developed to eliminate this adverse situation in recent years. One of these methods is Superconducting Fault Current Limiters (SFCL). With the discovery of High-Temperature Superconductors (HTS), SFCL's Resistive type has become more popular. Resistive SFCL (R-SFCL), based on the non-linear resistance property of superconducting materials, limits the fault within the first half period. However, it cannot provide such a fast response after the fault. The time required to regain the superconducting state after the fault is the recovery time. For R-SFCL manufacturers, recovery time is a design parameter that must be kept short. This study examines limiting performance, recovery time, and voltage stability with the dynamic model created using MATLAB/Simulink. With the shunt breaker method proposed in the study, the recovery time was shortened, and the voltage stability improved.

The Influence of Different Wall Materials on Liquid Metal Current Limiter

It is a valuable subject for academic community how to limit the short-circuit current within the breaking capacity of breakers at all levels. Liquid metal current limiter (LMCL) can tackle this challenge with its unique advantages. However, liquid metal and cavity of the existing LMCL are severely eroded, which limits the application. From the perspective of increasing the response speed, improving current-limiting efficiency, and reducing erosion, this article designs three LMCLs with polymethyl methacrylate (PMMA) material, ZnO pulse power resistance (ZnO PPR) material, and Kovar 4J29 material as the wall. Specifically, the wall is an important part of LMCL cavity with a channel. In addition, there is a discussion about the reasons for the different arc plasma intensity between the insulating wall LMCL and the resistive wall LMCL, from the point of current distribution. Furthermore, for Kovar 4J29 wall LMCL, the development process of the arc plasma is analyzed, and the effectiveness of the resistive wall LMCL is proven. Finally, the five current-limiting parameters of the three LMCLs under different short-circuit currents are compared and discussed. This article opens up a new approach for parameter optimization research and diversified development of LMCL.

Investigation of Vacuum Arc and Erosion Characteristics of Spiral TMF Contacts With Different Materials

The transverse magnetic field (TMF) can drive the arc to rotate, to reduce the erosion of contact. In this article, TMF contacts of six commonly used materials (CuCr10, CuCr30, CuCr50, WCu10, WCu30, and CuW-WC) are investigated by experiments at the current of 5, 10, and 15 kA. Experimental results show that the contact material has a significant impact on the arc, the arc on CuCr materials rotates, and shows noisy voltage, while the arc on WCu hardly rotates and exhibits a stable arc voltage because of staying in the diffuse mode. Though the erosion of CuCr contacts is more severe than WCu contacts, the results of breaking operations also indicate that CuCr contacts outperform WCu contacts, where CuCr10 contact has a lower breaking capacity than CuCr30 and CuCr50. Moreover, the steel support disk of the interrupter contacts plays a role in the reignition of the arc after a half-cycle of current which is obvious from the erosion of the disk and from records of the arc appearance.

3D transient MHD simulation of DC breaking vacuum arc based on artificial current zero

In the vacuum DC circuit breaker based on the artificial current zero, the change of arc luminosity delays the change of current value significantly in the fast current-zero stage. This phenomenon has impacts on the breaking capacity of the DC vacuum circuit breaker. Therefore, it is necessary to study the dynamic characteristics of the arc plasma under the above condition. In this work, a 3D transient magneto-hydro-dynamic model based on the commercial cup-type axial magnetic field (AMF) contact is established to study this phenomenon. The simulation results show that the fast current-zero stage is too short for the plasma to diffuse. The changes of the physical characteristics of the arc plasma lag the change of current value. Moreover, the magnetic field hysteresis caused by the eddy current on the electrode occurs in this stage, resulting in a continuous stronger AMF. It makes the distributions of the plasma uniform, while the diffusion of the arc plasma reduced at low currents, which is detrimental to the post-arc dielectric recovery stage. In addition, in the fast current-zero stage, the AMF near the contact slot is smaller than in other areas. This indicates that the slotting is effective in suppressing eddy currents and avoiding the negative effect of excessive AMF on plasma diffusion at this stage. The simulation results are consistent with the experimental results.

Development of a new hybrid DC circuit breaker

Hybrid DC circuit breaker has the advantages of short breaking time and low on-state loss. It is currently the mainstream solution used in DC transmission and distribution systems. However, the power electronic switch in the transfer branch limits the breaking capacity of the equipment and also the breaking cost per unit capacity is increased, which severely restricts the large-scale application and promotion of hybrid DC circuit breakers. In order to solve this problem, this paper proposes a new type of hybrid DC circuit breaker scheme. Firstly, its topology and working principle are explained, the current and voltage stress of key components are analysed, and then a simulation model is built. The breaking process is simulated, and the design of the test prototype is completed on this basis. Finally, a LC low-frequency oscillation test circuit is built to verify the breaking performance of the developed hybrid DC circuit breaker prototype. The results show that the developed prototype successfully breaks 50kA short-circuit current within 3 ms, which is basically consistent with the simulation results, and provides a reference for the subsequent development of large-capacity medium-voltage DC circuit breakers.

Motion Characteristic Detection of Operating Mechanism Based on Image Processing

It is important for the study of circuit breaker opening capacity to know how to accurately measure the movement characteristics of the actuator. In order to measure the motion characteristics of the actuator accurately, an image processing method based on LabVIEW platform is proposed in this paper to build a system for detecting the motion speed of the actuator. In this paper, a high-speed camera is used to capture the motion images of the circuit breaker during the opening process, and the VISION module in LabVIEW is used to locate the motion edges with high accuracy, calculate the motion parameters of the moving end during the motion process, and evaluate the opening capacity of the circuit breaker by combining the motion parameters. The experimental results show that the proposed method can achieve accurate detection of the motion parameters of the operating mechanism, and has the advantages of high accuracy and simple operation, which can provide strong technical support for the study of the breaking capacity of the circuit breaker.

Analysis of Combined Resistive Superconducting Current Limiter

Based on a brief analysis of the discovered quench mechanism and basic model of the resistive superconducting current limiter, in order to alleviate the defects of the conventional resistive superconducting current limiter, a Combination of fault current limiting operating modes of the current transformer. A custom model of resistive superconducting current limiter was built on the PSCAD/EMTDC simulation platform, and based on a 200kV DC transmission system, the influence of the combined operating mode resistive superconducting current limiter on the circuit was studied, and it was shown that the Define the correctness and necessity of the model. The simulation results show that the resistive superconducting current limiter in the combined operation mode can effectively suppress the short-circuit fault current, reduce the system’s requirements for the breaking capacity of the DC circuit breaker, and improve the safety of the system operation.

Short-Circuit Fault Current Modeling of a DC Light Rail System with a Wayside Energy Storage Device

This paper proposes a simulation model to calculate short-circuit fault currents in a DC light rail system with a wayside energy storage device. The simulation model was built in MATLAB/Simulink using the electrical information required to define a comprehensive DC traction power rail system. The short-circuit fault current results obtained from the simulation model were compared with hand calculation results obtained using EN 50123-1 guidance. The relative error was 1.02%, which validates the model. A case study was carried out for a 1500 V DC light rail system. In the case study, a method was proposed to assess the DC protection and the withstand and breaking capacity of the DC circuit breakers for maximum current and distant faults. A traction power modeling simulation was conducted for the 1500 V DC light rail system to calculate the maximum load current in the analyzed electrical sections. It is concluded that the proposed simulation model and fault methodology can be used for DC protection settings calculations and DC circuit breaker rating analysis.

The Influence of Novel Power System Characteristics on 330kV Power Grid Short-circuit Current

Under the development goal of “Carbon Peak, Carbon Neutralization”, the concept of novel power system is proposed. Its representative features include AC/DC interconnection of power grid and large-scale access of new energy power stations. Under these characteristics, higher requirements are put forward for the short-circuit current breaking capacity of the circuit breaker. The DC component of short-circuit current and the injection of new energy into the system short-circuit current cannot be ignored. Based on the 330kV local power grid in Northwest China, this paper studies the power grid operation mode, DC component of short-circuit current and the influence of photovoltaic power station on short-circuit current. The influence law of DC component of short-circuit current on the actual breaking capacity of circuit breaker and access of photovoltaic power station on the short-circuit current are summarized. It can provide a theoretical basis for the selection of circuit breaker in novel power system.