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The characteristics and types of prestrike are critical factors affecting the performance of vacuum circuit breakers (VCBs) in controlled switching. However, there is a lack of studies on the prestrike characteristics and types in vacuum interrupter (VI) after inrush current erosion. This paper investigates the prestrike characteristics and types in VI after inrush current erosion, using a novel method for measuring field emission current under DC voltage. Through experiments, the prestrike characteristics after inrush current erosion were obtained, including prestrike dispersion and prestrike gap. Furthermore, based on the prestrike gap and field emission current, the prestrike types observed in the experiments were classified into three categories: field emission induced prestrike (FEPS), particle-induced prestrike (PPS) and field emission-particle induced prestrike (FE-PPS). The average prestrike gap for these three types were 1.525 mm, 3.809 mm, and 2.887 mm, respectively. PPS showed no significant field emission current, while the field emission current at prestrike moment for FE-PPS was approximately 48.89% of that observed in FEPS. These findings have important implications for the development of controlled switching technology in VCB.

This paper proposes a thyristor-based hybrid DC circuit breaker (HDCCB), which is composed of a fast mechanical circuit breaker and an LC resonant circuit with thyristor switches. The proposed HDCCB provides a zero-crossing point for fault current by injecting a resonant current in the reverse direction of the fault current. The proposed HDCCB has a low conduction loss in normal operation using a mechanical circuit breaker, and it offers the advantages of low cost, high reliability, and large capacity using thyristor switches instead of IGBT switches. It also has the design flexibility to adjust the magnitude of the injection current depending on the fault current level. A bidirectional HDCCB is also proposed by adding several components to the developed unidirectional HDCCB, which can offer compact system size and low system cost. Design considerations of the proposed structure are discussed. The validity of the proposed HDCCB is verified by simulation and experimental results.

High voltage direct current (HVDC) systems are efficient solutions for the integration of large-scale renewable energy sources with the main power grids. The rapid development of the HVDC grid has resulted in a growing interest in DC circuit breakers (DCCBs). A fast and reliable circuit breaker is a necessary requirement in the development of large scale HVDC grids. This paper provides a comprehensive review and survey of the HVDC CBs and discusses potential research directions. Operational principles and the main features of various DCCBs are described and their merits and shortcomings are also highlighted.

Mechanical faults are the main causes of abnormal opening, refusal operation, or malfunction of high-voltage circuit breakers. Accurately assessing the operational condition of high-voltage circuit breakers and delivering fault evaluations is essential for the power grid’s safety and reliability. This article develops a circuit breaker fault monitoring device, which diagnoses the mechanical faults of the circuit breaker by monitoring the vibration information data. At the same time, the article adopts an improved deep learning method to train vibration information of high-voltage circuit breakers, and based on this, a systematic research method is employed to identify circuit breaker faults. Firstly, vibration information data of high-voltage circuit breakers is obtained through monitoring devices, this vibration data is then trained using deep learning methods to extract features corresponding to various fault types. Secondly, using the extracted features, circuit breaker faults are classified and recognized with a systematic analysis of the progression traits across various fault categories. Finally, the circuit breaker’s fault type is ascertained by comparing the test set’s characteristics with those of the training set, using the vibration data. The experimental results show that for the same type of circuit breaker, the accuracy of this method is over 95%, providing a more efficient, intuitive, and practical method for online diagnosis and fault warning of high-voltage circuit breakers.

Circuit breakers (CBs) are the main protection devices for both alternating current (AC) and direct current (DC) power systems, ranging from tens of watts up to megawatts. This paper reviews the current status for solid-state circuit breakers (SSCBs) as well as hybrid circuit breakers (HCBs) with semiconductor power devices. A few novel SSCB and HCB concepts are described in this paper, including advantage and limitation discussions of wide-band-gap (WBG) devices in basic SSCB/HCB configuration by simulation and 360 V/150 A experimental verifications. Novel SSCB/HCB configurations combining ultra-fast switching and high efficiency at normal operation are proposed. Different types of power devices are installed in these circuit breakers to achieve adequate performance. Challenges and future trends of semiconductor power devices in SSCB/HCB with different voltage/power levels and special performance requirements are clarified.

Low voltage direct current (LVDC) distribution has gained the significant interest of research due to the advancements in power conversion technologies. However, the use of converters has given rise to several technical issues regarding their protections and controls of such devices under faulty conditions. Post-fault behaviour of converter-fed LVDC system involves both active converter control and passive circuit transient of similar time scale, which makes the protection for LVDC distribution significantly different and more challenging than low voltage AC. These protection and operational issues have handicapped the practical applications of DC distribution. This paper presents state-of-the-art protection schemes developed for DC Microgrids. With a close look at practical limitations such as the dependency on modelling accuracy, requirement on communications and so forth, a comprehensive evaluation is carried out on those system approaches in terms of system configurations, fault detection, location, isolation and restoration.

With the rapid advancement of digitalization and intelligence in power systems, SF6 high-voltage circuit breakers, as the core switching devices in power grid protection systems, have become critical components in high-voltage networks of 110 kV and above due to their superior insulation performance and exceptional arc-quenching capability. Their operational status directly impacts the reliability of power system protection. Therefore, real-time condition monitoring and accurate assessment of SF6 circuit breakers along with science-based maintenance strategies derived from evaluation results hold significant engineering value for ensuring secure and stable grid operation and preventing major failures. In recent years, the frequency of extreme weather events has been increasing, necessitating a comprehensive consideration of both internal and external factors in the operational status prediction of SF6 high-voltage circuit breakers. To address this, we propose an operational status assessment model for SF6 high-voltage circuit breakers based on an Integrated Attribute-Weighted Risk Model Based on the Branch–Trunk Rule (IAR-BTR), which integrates internal and environmental influences. Firstly, to tackle the issues of incomplete data and feature imbalance caused by irrelevant attributes, this study employs missing value elimination (Drop method) on the fault record database. The selected dataset is then normalized according to the input feature matrix. Secondly, conventional risk factors are extracted using traditional association rule mining techniques. To improve the accuracy of these rules, the filtering thresholds and association metrics are refined based on seasonal distribution and the importance of time periods. This allows for the identification of spatiotemporally non-stationary factors that are strongly correlated with circuit breaker failures in low-probability seasonal conditions. Finally, a quantitative weighting method is developed for analyzing branch-trunk rules to accurately assess the impact of various factors on the overall stability of the circuit breaker. The DFP-Growth algorithm is applied to enhance the computational efficiency of the model. The case study results demonstrate that the proposed method achieves exceptional accuracy (95.78%) and precision (97.22%) and significantly improves the predictive performance of SF6 high-voltage circuit breaker operational condition assessments.

Advances in medium voltage direct current (MVDC) technologies and the penetration of extended MVDC systems are still significantly hindered by the lack of adequate direct current (DC) switching equipment. The fundamentally different fault current behavior in case of a DC fault, compared to faults in alternating current (AC) systems, with regard to the characteristics and development of fault currents and their interruption make dedicated test procedures necessary. One testing approach is the application of a power-electronic buck converter (PEBC) to simulate relevant stresses on DC switching equipment during a DC fault current interruption. Since the associated requirements, especially regarding current ratings of several kiloamperes, cannot be fulfilled by using a singular PEBC, a modularization becomes necessary. However, particularly in high-power applications, the interconnection of several PEBC modules poses significant challenges. In this article, a demonstrator PEBC-based high-power test circuit for the provision of relevant testing parameters is presented. The underlying challenges and respective solutions with regard to the interconnection of, in total, 120 individual PEBC modules are discussed. It can be shown that the harmonization of connection busbar inductances is the main contributor towards a stable and safe test circuit operation.

A circuit breaker is a crucial component in power systems, and its operation is essential for evaluating its interruption performance. However, electromagnetic interference often affects sensor accuracy. To address this issue, this paper investigates a non-contact measurement technique for assessing the motion characteristics of circuit breakers. A motion detection method based on Franklin moments is proposed. A synchronous image acquisition platform was established using high-speed cameras to capture the motion of 252kV circuit breakers. The captured images are preprocessed, with coarse edges extracted using the Laplacian algorithm. Franklin moment convolution calculations are then applied to determine sub-pixel coordinates of the image edges based on these coarse edges. By analyzing the frame-to-frame variations of these sub-pixel coordinates, the opening motion characteristics of the circuit breaker are extracted. This method can detect the vibration parameters and bouncing phenomenon of circuit breaker motion machine in millisecond level, and the accuracy is 0.01 mm. These findings offer valuable insights for future research on circuit breaker performance.

This paper deals with circuit breakers (CBs) used in direct current microgrids (DCMGs) for protection against electrical faults, focusing on their evolution and future challenges in low voltage (<1.5 kV) and medium voltage (between 1.5 kV and 20 kV). In recent years, proposals for new circuit-breaker features have grown. Therefore, a review on the evolution of circuit breakers for DCMGs is of utmost importance. In general terms, this paper presents a review concerning the evolution of circuit breakers used in DCMGs, focusing on fuses, mechanical circuit breakers (MCBs), solid-state circuit breakers (SSCBs), and hybrid circuit breakers (HCBs). Their evolution is presented highlighting the advantages and disadvantages of each device. It was found that although modern circuit breakers have begun to be commercially available, many of them are still under development; consequently, some traditional fuses and MCBs are still common in DCMGs, but under certain restrictions or limitations. Future challenges that would allow a successful and adequate implementation of circuit breakers in DCMGs are also presented.