Conventional Circuit Breakers Research Articles

Hybrid Z-Source Circuit Breaker with Thomson Coil for MVDC

Hybrid circuit breakers are the most promising circuit breakers among DC circuit breakers. Conventional hybrid circuit breakers complete fault current isolation by converting current to IGBT when fault current occurs. However, in this case, the fault current continues to increase, so the IGBT must be large enough to withstand this current. In addition, in the case of a method of detecting and operating a fault, a delay time of up to hundreds of microseconds occurs, and in a hybrid circuit breaker, this delay time is a very large value. To solve this problem, this paper proposes a hybrid Z-source circuit breaker that operates without delay for low-impedance faults. The proposed breaker is designed to reduce stress on IGBTs and mechanical switches by generating a current zero crossing, as well as to enable the breaker to trip quickly in high-risk cases such as low-impedance fault circuits. Due to the limited environment of the laboratory, we performed 600 V fault isolation experiments. As a result of the experiment, it was confirmed that the proposed circuit breaker successfully isolated the fault within 1.6 ms. The current limiting feature of the Z-source appears to reduce stress on the IGBTs and MOVs used, and it allows for faster fault isolation.

Analysis and Optimization of Contact Material Ablation under the Cumulative Effect of the Number of Breakings of OLTC.

Vacuum on-load tap-changers (OLTC) for converter transformers have a much higher number of breakings than conventional circuit breakers. Contact ablation after several breakings will affect the stability and life of the device. This paper establishes the electromagnetic thermal multi-physical field coupling model of the vacuum interrupter for OLTC based on the finite element analysis method. The thermal field distribution of normal and ablative contact materials during the breaking process was analyzed. The key parameters affecting the contact temperature under the cumulative number of breakings are analyzed and the optimized design is completed. The simulation results show that the contact surface reaches a maximum temperature of 1390 K at 8 ms. There is a significant increase in the area of the high-temperature area on the contact surface. The possibility of re-ignition of the interrupter is increased. Based on the judgment matrix method, the key influencing parameters of the contact temperature rise are analyzed. The final parameters are selected as follows: contact material-CuCr8 alloy, contact seat thickness-2 mm, contact thickness-10 mm, and contact diameter-40 mm.

An Overview of DC Microgrid Protection Schemes and the Factors Involved

The development of a suitable scheme for protection of DC microgrids is still a major challenge. This is due to the shortage of practical experience in appropriate protection guidelines and standards related to the uncertainty in the network topology, absence of a natural current zero-crossing point in DC systems, and dependence of fault current shape and magnitude on various factors. These factors include network topology, type of converters used in the network, type of fault and its location, fault impedance, and type of system grounding. In this paper, these factors and their impacts on the development of a comprehensive protection plan for DC microgrids have been investigated. Various algorithms that have been proposed in previous studies for fault detection and location are reviewed, and the technical challenges associated with the use of communication links in smart protection systems are described. In addition, the advent of new technologies for development of DC circuit breakers are reported, which are different from the conventional AC circuit breakers due to the differences between the faults in DC and AC microgrids and their respective clearance times. This comprehensive review covers all aspects of the DC microgrid protection including topology, converters, configurations, and types of faults.

A Load-Independent Controllable Z-Source Circuit Breaker With an Intrinsic Fault Detection Method

The Z-source circuit breaker using thyristor as the main switch benefits from its low cost, low conduction loss, and high ruggedness. However, the fault protection of the conventional Z-source circuit breakers only relies on the change of the load. In this paper, a load-independent controllable Z-source circuit breaker (CZCB) with an intrinsic fault detection circuit is proposed. It will not be protected by mistake during any load step change, and an accurate fault current detection can be achieved with a specific threshold. Meanwhile, the fault current is monitored by the on-state voltage of the main thyristor, so no additional sensor is needed. An auxiliary thyristor is used to turn off the main thyristor reliably when an overcurrent is detected. In addition, only one inductor is needed in the CZCB, and the <i>L-C</i> parameter is much smaller than the conventional Z-source breakers, leading to lower size and cost. The performance of the proposed CZCB is verified by simulation and experiment. The results show that the fault current can be cleared within a few microseconds, and the total fault isolation time is only about 38 <i>&#x03BC;</i>s.

Fault Diagnosis of Conventional Circuit Breaker Accessories Based on Grayscale Image of Current Signal and Improved ZFNet-DRN

Considering that the randomness of the closing phase of the coil circuit for a low-voltage conventional circuit breaker (CCB) will lead to the difference of current signal under the same operation, a fault diagnosis method of switching accessories based on the grayscale image of the current signal and deep residual network (DRN) improved by Zeiler and Fergus Net (ZFNet-DRN) is proposed in this article. First, the signal stacking method is employed to convert the original 1-D current signal into a 2-D grayscale image, so as to retain the information contained in the signal to the greatest extent and avoid the insufficient amount of data input to the subsequent network model due to the limitation of 1-D data length. Second, regarding the diagnosis model, the improved ZFNet network realizes the deep extraction of features, DRN tackles the issue that the recognition rate decreases with the increase in the network depth, and the parametric rectified linear unit (PReLU) activation function and AMSGrad optimization algorithm are introduced to enhance its performance. Finally, the experimental analysis demonstrates that the diagnosis model can overcome the influence of the randomness of the closing phase and effectively complete the fault classification.

Remaining Useful Life Prediction for Circuit Breaker Based on SM-CFE and SA-BiLSTM

Targeting at the uncertainty of the degradation of conventional circuit breakers (CCBs) and the perfect mechanical degradation characterization by vibration signals, a remaining useful life (RUL) prediction method based on similarity measure (SM), comprehensive features extraction (CFE) and self-attention bidirectional long short-term memory network (SA-BiLSTM) is proposed in this paper. Firstly, the degradation-sensitive intrinsic mode functions (IMFs) of the vibration signals are separated by the SM method, and the reconstructed signals are divided into intervals based on the working process of CCBs to obtain the vibration signals for life prediction. Secondly, the explicit parametric features (EPFs) are obtained based on the vibration events and waveform features, and the implicit parametric features (IPFs) are extracted using the multi-scale convolutional auto-encoder (MSCAE). Next, the comprehensive features are obtained by combination of the EPFs and IPFs. On this basis, the degradation mode judgment method is formed by using the least square method (LSM) linear fitting of the EPFs. Finally, a quantitative life prediction model based on SA-BiLSTM is constructed, and greater weights are assigned to the important time steps. The proposed method is proved to show high prediction accuracy and good stability, which is more advantageous compared with other hybrid prediction models.

Remaining Useful Life Prediction for Circuit Breaker Based on Opening-Related Vibration Signal and SA-CNN-GRU

In order to realize the prediction of the remaining useful life (RUL) of the low-voltage conventional circuit breaker mechanical system in the whole life cycle, a prediction method based on opening-related vibration signal and stage attention hybrid neural network is proposed. The opening vibration signal contains richer mechanical state information. Therefore, the variational mode decomposition (VMD) based on energy loss is used to reconstruct the signal to increase the time-domain identification of the shock characteristics of the vibration signal, and the double threshold method (DTM) based on short-time energy entropy ratio (STEER) is used to realize the segmentation of the opening-related vibration signal. A stage attention mechanism (SA) is proposed, combining the convolutional neural network (CNN) and the gated recurrent unit (GRU) to construct the SA-CNN-GRU hybrid model. The first-stage distributed attention (DA) acts on the CNN to refine the mining of the information sensitive to degradation in the time and feature dimensions, and the second-stage time-step attention (TA) acts on the GRU to learn the time-series gradual information of the degradation process in a targeted manner and eliminate the influence of the degradation uncertainty of the complex system. Using the vibration data of three circuit breakers to test, the results show that the proposed method can solve the RUL prediction problem of circuit breaker mechanical systems and have high prediction stability, and the introduction of SA can effectively improve the prediction performance of the model.

A hybrid circuit breaker with fault current limiter circuit in a VSC-HVDC application

A conventional hybrid circuit breaker (HCB) is used to protect a voltage source converter-based high voltage direct current transmission system (VSC-HVDC) from a short circuit fault. With the increased converter capacity, the DC protection equipment also requires a regular upgrade. This paper adopts a novel type of HCB with a fault current limiter circuit (FCLC), and focuses on the responses of voltage and current during DC faults, which are associated with parameter selection. PSCAD/EMTDC based simulation of a three-terminal VSC-HVDC system confirms the effectiveness and value of HCB with FCLC, by using an equivalent circuit modelling approach. Laboratory experimental tests validate the simulation results. The peak fault current is reduced according to the current limiting inductor (CLI) increase, and can be isolated more quickly. By adopting parallel metal oxide arrester (MOA) with the main branch of HCB, voltage stresses across the breaker components decrease during transient and continuous operation, and less energy needs to be dissipated by the MOA. The remnant current for all cases is transmitted to power dissipating resistor (PDR) in the final stage, and the fault current is reduced to the lowest possible value. When the current from the main branch is transferred to the FCLC branch, transient voltage spikes occur, while smaller PDR is required to absorb current in the final stage.

Fault Diagnosis for Conventional Circuit Breaker Based on One-Dimensional Convolution Neural Network

Fault Diagnosis for Conventional Circuit Breaker Based on One-Dimensional Convolution Neural Network

A Surgeless Diode-Clamped Multilevel Solid-State Circuit Breaker for Medium-Voltage DC Distribution Systems

In conventional medium-voltage solid-state circuit breakers (SSCBs), series-connected semiconductor switches are used with metal oxide varistors (MOVs) in parallel with each of them to extend the voltage ratings of the breakers without incurring the dynamic voltage unbalance. Besides, for isolating the faults at faster speeds, the clamped surge voltages of the MOVs are always much higher than the system voltages. For those reasons, the voltage ratings of all the switches in the SSCBs have to be overdesigned according to the surge voltage values, which causes high material costs along with nonideal conduction losses in the SSCBs employed for medium-voltage dc distribution systems. To solve this dilemma, a surgeless diode-clamped multilevel SSCB is proposed in this article. It offers an ultrafast isolation speed with no significant surge voltages or dynamic unbalanced voltage across the semiconductor switches. With these attributes, the proposed SSCB can potentially use the semiconductor switches rated at lower voltages compared to conventional SSCBs and have higher efficiency along with faster isolation speed. The simulation and experimental results are presented to validate the technical feasibility and practical values of the proposed SSCB.

On-line mechanical life prediction method for a conventional circuit breaker based on multi-parameter particle swarm optimization-support vector regression using vibration detection

For on-line mechanical condition monitoring of conventional circuit breakers, based on the analysis of vibration signal measurements and the generation principle in the circuit breaker breaking motion process, the time parameters for mechanism action with clear physical meaning are correlated with vibration events. Thus, an on-line mechanical life prediction method based on vibration detection and multi-parameter support vector regression (MP-SVR) optimized by particle swarm optimization is proposed. This method aims to use the action time parameter as the main monitoring parameter to reflect the degradation of mechanical conditions and the life failure criterion. First, the complete MPs of life degradation are obtained through the designed on-line measurement algorithm for the action time parameter and the assisted time-domain features of vibration signals in the corresponding time. Then, a quantitative life prediction model is constructed based on MP-SVR. Finally, the degraded MPs are used as input to the prediction model to predict the remaining mechanical life. Our experiment shows that this on-line model for life evaluation is definitely effective and practical in engineering applications.

Study and Analysis of Different Types of Circuit Breaker

Circuit breakers play an important role in an electrical system performance in terms of system safety, control, maintenance and cost. In some cases, the conventional mechanical circuit breakers (MCB) may be too slow for the electrical network to operate within the desired safety limits. Besides their other limitations, the MCB also forces the network elements to be rated much higher. The uses of power semiconductor devices to overcome some of their limitations are discussed in this paper. These usages are in terms of solid state circuit breaker (SCB) and hybrid circuit breaker (HCB) concepts. This paper summarizes and reviews the various circuits of SCB and HCB available in the literature. The relevant simulation results for some example circuits have also been presented in this paper. This study will provide a useful framework and point of reference for the future development of HCB and SCB technologies. The breaker can not only open a circuit in response to a current spike, but can also react to a sustained moderate current draw, just above its rated current. Operation of the circuit breaker is simple, but utilizes complex mechanisms. Essentially there are to main internal mechanisms; the trigger and the switch. The trigger is the device that senses the abnormal current load. A sharp spike in current will cause a magnetic field to form in the trigger, releasing the switch. A slightly elevated, but more constant current draw through the breaker will cause the bi-metal composition of the trigger mechanism to deflect in an arc like manner, which is also capable of releasing the switch. The circuit breaker's best point is that the device is effective and compact. The switch can be set to open or closed from the outside of the breaker's case, but can only be set to the tripped position internally, as a results of the trigger mechanism. Once the breaker has been tripped internally, it must be reset externally by switching it off, and then back on. The features enable the breaker to do several jobs at once, eliminating the need for multiple elements in the circuit. For example, it provides the user with an easily assessable on/off switch, fault protection against current spike, and fault protection against heavy current draw. On the other hand it is not 100% effective and must also be manually reset which can be problematic if it is dark and no lights are available with which to see the fuse box. Another bad point is that the circuit breaker has many moving parts, which complicates construction. Simpler or fewer parts might drive cost down and make manufacturing more efficient.

Hybrid DC Circuit Breaker Using a SiC‐Semiconductor Module at 1 kA Interruption

Hybrid direct current circuit breakers (DCCBs) have become prominent because of their low on‐state power dissipation and small arc erosion compared with conventional semiconductor and mechanical circuit breakers (CBs). After a fault occurs in a DC circuit, the current commutates from the mechanical contacts to the semiconductor devices of the hybrid DCCB, and finally, the current is interrupted by the semiconductor devices. Thus, a low turn‐on voltage or a low on‐state resistance of the devices is needed to reduce the commutation time and power dissipation of the current interruption. This paper presents a comparison of DCCB performances metrics, such as the maximum interruption current, power dissipation, and junction temperature, using a silicon carbide metal‐oxide‐field‐effect transistor (SiC‐MOSFET) and silicon insulated‐gate‐bipolar transistor (Si‐IGBT) module. An interruption of 1.1 kA was achieved in 4.3 ms using the SiC‐MOSFET module of which rated current was 444 A. The junction temperature after the interruption was determined to be 275°C, which exceeded the maximum junction temperature of 175°C. In the case of the Si‐IGBT module of which rated current was 1110 A, the maximum interrupting current was limited to 900 A; however, the maximum junction temperature was 41°C. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

A new direct current circuit breaker with current regeneration capability

Direct current (DC) power systems are becoming very popular due to better control ability and equipment reliability thanks to the continuous development of power electronics. A DC circuit breaker (DCCB) used for current interruption in a DC network is a major part of the system. It plays the vital role of isolating networks during fault clearing as well as during normal load switching. Breaking the DC current is a major challenge as it does not have any natural zero crossing points like the AC current has. In addition, energy stored in the network inductances during normal operation opposes the instantaneous current breaking. Hence, all the conventional DC circuit breaker topologies use lossy elements to dissipate this stored energy as heat during the current breaking operation. However, it is possible to store this energy and reuse it later by developing an improvised topology. In this paper, the prospects of energy recovery and reuse in DC circuit breakers have been studied, and a new topology with regenerative current breaking capability has been proposed. This new topology can feed the stored energy of the network back into the same network after breaking the current and thus can improve the overall system efficiency.

Experimental Tests of Critical Current and AC Loss for a Self-Triggering High Temperature Superconducting Fault Current Limiter (SFCL) With Magneto-Biased Field

Rapidly growing power demands account for an increasing level of short circuit fault current in recent years. It is difficult for the conventional circuit breaker to meet the capacity requirements for fault current limiting. However, a high temperature superconducting fault current limiter (SFCL) can instantaneously protect power grids by using the HTS quench properties. The wide application of SFCL gives a new avenue for power grid protection. Therefore, SFCL have advantages in reducing the capacity of circuit breaker. A novel self-triggering SFCL with magneto-biased field was proposed in this paper. This SFCL has a non-inductive high temperature superconducting module, a reactor with two split symmetrical windings and a circuit breaker. The experimental platforms for test of the transport characteristic of SFCL unit are set up. A high-speed Data Acquisition (DAQ) System based on LABVIEW produced by NI Corporation is applied for experimental tests. The critical current and AC loss characteristics of a SFCL unit have been tested and compared considering the effects of joints. This SFCL has been validated and its technical feasibility in power grids is verified by experimental investigations.

기계식 DC 차단기에 적용 가능한 초전도 벌크 및 와이어 유형의 비교 분석

The core technology of the DC grid system is to protect the system in the event of a transient and to cut-off the faults current in a trouble line, quickly. We sat down to analyze to implement the DC breaking technology of mechanical DC circuit breaker on the faster and more safely. However, the mechanical DC circuit breakers have limitations on the opening speed and the components of the break contact. To solve this problem, we applied a superconducting electromagnet to a mechanical DC circuit breaker and proposed a method to reduce the DC Arc energy generated during the breaking operation. In this paper, we proposed the application of superconducting bulk-type magnet and superconducting wire-type electromagnet to the conventional mechanical DC circuit breaker and analysed the breaking characteristic. We designed a mechanical DC cutting-off contact, a superconducting bulk-type magnet, and a superconducting wire-type electromagnet through the Maxwell 3D program. As a result, the Lorentz force was generated between the mechanical DC cutting-off contacts each applied the superconducting bulk-type magnet and wire-type electromagnets. The superconducting bulk-type magnets produced a magnetic force of about 269.3 A/m and the superconducting wire-type electromagnet produced a magnetic force of about 610 A/m affecting DC arc blowing.

Remaining Life Prediction of Conventional Low-Voltage Circuit Breaker Contact System Based on Effective Vibration Signal Segment Detection and MCCAE-LSTM

In order to realize on-line mechanical life prediction of conventional low-voltage circuit breaker and improve its operation reliability, a life prediction method based on vibration signal detection is proposed. Firstly, the effective vibration segment that characterizes the mechanical performance of contact system are extracted by combining with the designed signal processing method; then, a multi-channel convolutional auto-encoder long short term memory network (MCCAE-LSTM) life prediction model for individual circuit breaker is constructed, in which the MCCAE is used to obtain the time sequential micro features rich in life degradation information, and the LSTM realizes the quantitative output of the remaining mechanical life; finally, through the actual mechanical life experiment and prediction performance analysis, the effective vibration segment can reflect the mechanical characteristics of the contact system, the measurement method is easy to be carried out on-line, and the average goodness of fit of the prediction model is improved by about 10% compared with the traditional method, which verify the effectiveness of the proposed method.

PSCAD/EMTDC를 활용한 초전도 소자의 유무에 따른 기계식 DC 차단기 분석

With the announcement of a policy to reduce carbon emissions, the range and technologies of renewable energy sources are increasing. In new renewable energy, the amount and range of solar power generation is relatively gradually expanding[1]. Based on the high-speed DC circuit breaker used in the solar power generation, we combined the LC divergence oscillation circuit and the superconducting element that this research team is working on. This is to protect peripheral equipment against an increase in solar power generation and unspecified disturbances. The DC circuit breaker, we propose is a mechanical DC circuit breaker with a superconducting element applied. The superconducting element can lower the initial fault current within about 2 ㎳ through the quenching operation. However, it takes a large power burden and a long time to cut-off the fault current. In the mechanical DC cut-off part, the existing high-speed mechanical circuit breaker, LC divergent oscillation circuit and Surge Arrestor are connected in parallel to safely and reliably cut off fault current. The characteristics of the cut-off operation that appear when a superconducting element and an LC divergent oscillation circuit are combined with a conventional mechanical DC circuit breaker were analyzed. As a result, through the application of the superconducting element, the speed at which the artificial zero-point of the fault current occurs was reduced, and the time to complete the shutdown was shortened.

Fault Diagnosis of Conventional Circuit Breaker Contact System Based on Time–Frequency Analysis and Improved AlexNet

In order to eliminate the influence of parameter predefined caused by manual feature extraction, achieve fast feature extraction, and improve the recognition rate of fault diagnosis, a 2-D convolution neural network (CNN) method for fault diagnosis of conventional circuit breaker contact system is proposed. First, by introducing the data preprocessing method of continuous wavelet transform (CWT), the nonlinear and nonstationary original vibration signal is transformed into a time–frequency image to extract the transformed image features. Second, the convolutional layer module in the AlexNet model is combined with the network in network (NIN) module, and the global average pooling (GAP) layer is adopted to replace the fully connected (FC) layer, which realizes the improvement of the traditional AlexNet model. Then, an improved Adam optimization algorithm, namely, AMSGrad, is adopted to solve the problem that the Adam optimization algorithm may not converge or produce local optimization during model training. Finally, the preprocessed time–frequency image is taken as the input of the improved AlexNet model and through the supervised adjustment of network parameters, the fault diagnosis of the contact system for the conventional circuit breaker is realized accurately.

A Modified Hybrid DC Circuit Breaker With Reduced Arc for Low Voltage DC Grids

The increasing demand for the development and utilization of renewable energy resources has lead to a growing interest in the development of LVDC systems. The dc grid provides more flexibility in integrating different forms of renewable energy sources effectively. However, the lack of a reliable protection mechanism remains the main drawback in the growth of dc distribution systems. Unlike ac systems, the absence of a natural zero crossing in dc systems for arc extinction makes the use of a conventional mechanical circuit breaker (MCB) a less reliable solution. The use of a solid-state circuit breaker (SSCB) results in fast fault interruption but reduces the overall efficiency of the system due to the on-state voltage drop of the semiconductor devices. A hybrid circuit breaker (HCB) combining MCB and SSCB yields better static and dynamic performances but the main challenges remains in the demagnetization of the transmission line inductance after a fault interruption and an arc formation between the MCB contacts. This paper proposes a hybrid circuit breaker (HCB) which is suitable for fast fault interruption in low voltage dc (LVDC) systems while alleviating the above issues. Proposed topology employs a semiconductor switch as well as an actively switched capacitor branch in parallel with the main mechanical breaker to facilitate fast current commutation during a fault. The mechanical breaker forming the main branch is turned off at zero voltage. This eliminates the arc formation across the moving contacts of the breaker. Moreover, the fault interruption process does not require a varistor for network demagnetization following the fault current commutation. This paper also presents a discharging mechanism for the capacitor in a practical implementation. Operation of the proposed dc circuit breaker is evaluated through a prototype tested in the laboratory.