Circuit Breaker Mechanism Research Articles

A Co-Simulation Model for the Operating Mechanism of a High-Voltage Circuit Breaker

A Co-Simulation Model for the Operating Mechanism of a High-Voltage Circuit Breaker

Does emergency policy mend the fold after the sheep have been stolen?- an empirical study on the Baiyin Cross-country race and its subsequent circuit breaker mechanism

This study examines the biggest disaster in the history of international trail running—the Huangshi Cross-Country Race in Baiyin city, China—as an example to quantitatively evaluate this large-scale sporting event's impact on the local economy. After calculating the city stock market returns based on the improved worst-case Value-at-Risk (WCVaR) designed for this study, this study proposes a hybrid forecasting method combining time series modelling and neural network autoregression (NNAR) models to quantify the net effect of the race disaster, through counterfactual information. The study discoveres that although the event's pre-publicity period positively stimulated Baiyin city's economy, it still could not offset the negative impact of unexpected events during the race. Then, the study further explores the net economic effect of the circuit breaker mechanism as a strategic tool in an attempt to quell the above-mentioned negative effects after the cross-country race, through applying a difference-in-differences method to regress and analyse the stock market yield panel data of Baiyin and its control cities before and after the policy's implementation. Subsequently, it was revealed that the circuit breaker mechanism could not effectively curb the spread of the disaster's negative influence, in other word, the circuit breaker exists only to ‘mend the fold’ after the ‘sheep’ are endangered and it is already too late.

Deep auto-encoder network for mechanical fault diagnosis of high-voltage circuit breaker operating mechanism

Abstract To improve the accuracy of the mechanical fault diagnosis of the operating mechanism and fully exploit the characteristic information in the vibration signal of the high-voltage circuit breaker, a mechanical fault diagnosis method of the operating mechanism of the high-voltage circuit breaker based on the deep self-encoding network is proposed. First, the vibration signal of the switch operating mechanism is extracted, the wavelet packet conversion is performed, and the vibration signal of each frequency band is divided into equal times. The energy of the time–frequency subplane of the vibration signal is then calculated, and the time–frequency energy distribution is used as a switch. Finally, a breaker failure diagnostic model based on the deep self-coding network is established. Pretraining and tuning and a 126 kV high-voltage switch are used to simulate different types of faults and validate the method. Experimental results show that this method can acquire sample failure data and perform failure diagnosis, and the diagnosis accuracy rate reaches 97.5%. The deep self-coding network can fully pierce deep information on the switch vibration signal.

Acceleration of distance protection second zone: A non-pilot method based on the healthy phases data

Nowadays, power systems are operated closer to their stability margins and therefore, the need for faster protection algorithms is escalated. The second zone of distance protection is conventionally set to operate with some lengthy delay, which increases the fault clearing time for the end part of the protected line. Therefore, the acceleration of zone-2 for internal faults can remarkably increase the speed of line protection. This practice is traditionally performed by pilot protection systems, which rely on communication channels. This paper proposes a new non-pilot solution to this challenge using only local measurements. A phasor-based algorithm is proposed to detect the remote circuit breaker operation (RCBO) using the healthy phases data. The proposed method has been developed for both single- and three-pole circuit breaker (CB) mechanisms, which makes it practical for transmission and sub-transmission lines. Thanks to using the healthy phases data, the proposed method is immune to the current transformer saturation and capacitor voltage transformer transients. The performance of the proposed method is simulated and investigated in various critical situations besides some experimental tests. The obtained results approve the efficiency and robustness of the proposed method for different scenarios, e.g. noisy conditions, evolving faults, and parallel lines.

On the contagion leakage via incoming flights during China’s aviation policies in the fight against COVID-19

For nearly three years with the COVID-19 pandemic, China has implemented a set of strict policies to control the flux of potential virus carriers in cross-border flights: The so-called Circuit Breaker mechanism. In this study, we review the evolution of this mechanism – a rather unique experiment in the global aviation system — from a data-driven perspective. Specifically, we perform an investigation on the extent of violations and their potential drivers. In total, 183 events are analyzed covering the period from epidemic outbreak in early 2020 to December 2021. In addition to describing the spatial extent and temporal evolution, we develop a regression model which helps us to better understand the universal patterns. By dissecting an under-investigated phenomenon, we believe that our study contributes to the rich literature on aviation and COVID-19, not only in the specific context of China, but also by assessing some of the challenges and potential of containing a global health threat using strict aviation policies.

Does the Emergency Policy Mend the Fold after the Sheep Have Been Stolen?- an Empirical Study on the Baiyin Cross-Country Race and Circuit Breaker Mechanism

Does the Emergency Policy Mend the Fold after the Sheep Have Been Stolen?- an Empirical Study on the Baiyin Cross-Country Race and Circuit Breaker Mechanism

Design and Research of Operating Repulsion Mechanism Suitable for 252kV High-Speed Breaking Circuit Breaker

This paper proposes a high-speed operating repulsive force mechanism suitable for 252kV high-voltage circuit breakers. The mechanism draws on the working principle of the electromagnetic repulsion operating mechanism of the medium voltage circuit breaker, and combines the new electromagnetic fast repulsion device with the traditional disc spring hydraulic mechanism to realize the fast action of the circuit breaker. This paper first introduces the working principle of the electromagnetic repulsion operating mechanism, and proposes the initial design scheme of the mechanism. Subsequently, the digital twin technology was used to establish the rigid-flexible coupling multi-body dynamics model of the mechanism, and the defects of the initial scheme were analyzed based on simulation. Finally, the paper optimized the design of the initial scheme and verified it by simulation. The test shows that the 252kV high-voltage circuit breaker with the improved scheme as the operating mechanism works normally and can complete the fault breaking within 20.1ms, which is twice as fast as the current products of the same type.

The effect of aviation responses to the control of imported COVID-19 cases

The outbreak of the COVID-19 pandemic has a lasting and unprecedented negative impact on the global aviation industry. While countries such as China have successfully curbed the domestic outbreak of the virus with various restrictive and preventive measures, the challenge of avoiding imported cases remains. More importantly, it is still unclear to what extent these implemented aviation emergency responses have effectively mitigated the transmission risk of the virus. This paper provides an empirical assessment of aviation responses to the control of imported COVID-19 cases, with a focus on the following three strategies: the “circuit breaker” policy, the “negative Nucleic Acid testing (NAT)”, and the “double negative tests” requirement. Non-recursive structural equation models (SEM) with latent variables were applied to detailed international flight data and individual epidemic survey data of Guangzhou, China, between May 1 and November 30, 2020. The results show that the “double negative tests” measure has a positive effect on eliminating the number of SARS-CoV-2 carriers, while the effects of single “circuit breaker” and its co-intervention with “negative NAT” are conterproductive. This study provides important implications to civil aviation agencies in regard to medium and long-term risk control of imported cases. Specifically, although the circuit breaker mechanism was designed to target on the risk control of imported COVID-19 cases, it may be more effective to carefully maintain a timely and reliable pre-boarding screening and testing to curb the number of imported cases.

Miniaturization design of closing electromagnet for fast contact mechanism of DC circuit breaker in power grid

The newly designed DC circuit breaker closing electromagnet must meet the requirements of small size and fast action. This article focuses on the design index of the electromagnet, and carries on the preliminary design based on the empirical formula. On this basis, with the smallest volume as the objective function, a steady-state simulation design is carried out using BOBYQA's optimization algorithm. The design results are input into the transient simulation model to solve and analyze the characteristic changes of the solenoid coil voltage and current. Simulation and prototype test results show that under AC220V 50Hz full-wave rectification excitation, the moving iron core starts to move in 18.8ms and completes a 6mm stroke in 30.8ms; the peak coil current during the continuous flow is 4.15A, which meets the design index requirements of the electromagnet. The new scheme provides a reference for the design of DC circuit breaker closing device.

Improving the cam profile of the spring operating mechanism of vacuum circuit breaker based on energy matching

High-voltage circuit breakers are important protection and control equipment in power systems. In order to understand the mechanical characteristics of vacuum circuit breaker, the mathematical relationship between the released energy of closing spring, the stored energy of opening spring and overtravel spring and the rotation angle of output crank arm is studied. The characteristic curve between the released energy of closing spring and the rotation angle of output crank arm and the characteristic curve between the stored energy of opening spring and overtravel spring and the rotation angle of output crank arm are drawn by MATLAB. In order to improve the matching of energy release and energy storage characteristic curves, a method of improving cam profile is proposed. The dynamics simulation model of spring operating mechanism of high voltage circuit breaker is established and the original cam and adjusted cam are imported into the dynamics simulation model of mechanism. The simulation results show that the adjusted cam improves the closing speed of vacuum circuit breaker. This helps to reduce the stress on the parts of the vacuum circuit breaker and increase the service life of the vacuum circuit breaker.

Preparing for market disruption: circuit breakers and discretionary trading halts

Purpose This article provides a resource for traders and other market participants by providing an overview of certain automatic circuit breaker mechanisms and discretionary powers that the U.S. Securities and Exchange Commission (SEC), Financial Industry Regulatory Authority (FINRA) and the U.S. president, as applicable, can exercise to pause or stop the trading of individual securities or trading activities across exchanges during extreme market volatility, each of which can cause interruptions to trading activity. Design/methodology/approach This article surveys automatic and discretionary mechanisms to halt trading activity under extreme market conditions. In particular, the article examines automatic cross-market circuit breakers, limit up-limit down pauses, the alternative uptick rule, as well as discretionary authority to stop short selling of particular securities and to stop trading across exchanges. Findings The article concludes that market participants must be cognizant not only of automatic cross-market circuit breakers, but also several other forms of potential market disruptions that may occur due to increased market volatility during the COVID-19 pandemic and beyond. Originality/value By exploring various mechanisms that respond to market disruption, this article provides a valuable resource for traders and other market participants looking to identify and respond to potential interruptions to their trading activity.

Modeling and dynamic simulation of operating mechanism of high voltage circuit breaker with a hydraulic buffer

Modeling and dynamic simulation of operating mechanism of high voltage circuit breaker with a hydraulic buffer

Research on the Difference Mechanism of High Voltage Circuit Breaker’s Opening/Closing Coil Current

High voltage circuit breakers are important protection and control equipment for the power grid. The defects and faults of the circuit breaker seriously affect the safety and stability of the power system. As the key component of the operating mechanism of the circuit breaker, the opening/closing coils contain a large amount of information about the operating status of the mechanism. In order to investigate the cause of the difference in the current waveforms, this paper analyzes the factors affecting the circuit breaker opening/closing coil current based on the actual high voltage circuit breaker, and distinguishes the characteristics of the current caused by the environmental difference and Structural difference. At the same time, the characteristics of coil current changes under four different types of mechanism defects are analyzed. These results lay the foundation for status evaluation of high voltage circuit breakers based on opening/closing coil current.

Dynamic Simulation Optimization of Vacuum Circuit Breaker Based on Virtual Prototype

In order to study the mechanical characteristics of the vacuum circuit breaker, virtual prototype technology is used to establish a dynamic simulation model of the operating mechanism of the VS1 vacuum circuit breaker, and the dynamic characteristics of the opening and closing process of the circuit breaker are obtained. Then on this basis, in order to reduce the closing bounce of the circuit breaker, the various parameters of the mechanism that affect the closing bounce are selected as design variables for optimization and improvement. The simulation results prove that appropriately increasing the preload of the contact spring can effectively reduce the closing bounce.

Policy Effectiveness Analysis of China’s Circuit Breaker Mechanism

From June to August 2015, China’s security market suffered a severe decline due to the impact of the stock market crash. For this reason, the Shanghai Stock Exchange issued a notice on December 4, 2015, deciding to implement the circuit breaker mechanism on January 1, 2016. However, the mechanism was abolished only four days after its implementation. Therefore, this paper provides an empirical effectiveness analysis of this circuit breaker mechanism based on the nine CSI 300 industries using the regression discontinuity design method. The empirical results show that the implementation of the circuit breaker mechanism has led to the breakpoints of volatilities in nine industries and has significantly increased its market fluctuation. Moreover, we also find that the implementation of the circuit breaker mechanism has different impacts on the different industries, such as the effectiveness of the public, and consumer industries are at the medium level and show more stable fluctuations. Therefore, we suggest that the further circuit breaker mechanism in China’s financial markets can be piloted from the public and consumer industries rather than directly implementing it on the whole CSI 300.

The design and implementation of a campus web information system based on micro-service architecture

In the development of Web information system, the traditional monolithic application architecture is simple and effective for small-scale projects. Because all business logics are combined together in those projects, secondary development and maintenance become very difficult. In recent years, there are methods to solve this problem, which are popular Web distributed architecture solution. The first step of the solution is to separate front-end and back-end of Web system and the second step is to decompose system’s services into micro-services. Micro-service architecture splits application into smaller scale services and each service completes only performs special function. Through service registration centre, micro-service architecture provides unified mechanism of service discovery and registration, it provides unified interfaces for calls from front-end through gateway technology; it protects stability and fault tolerance via back-off mechanism and circuit-breaker mechanism. We have developed a campus Web information system, which adopts two techniques, the separation of front-end and back-end and micro-service architecture By using Spring Cloud framework as back-end developing architecture, the solution of splitting application to micro-services is obtained, and then problems in monolithic application architecture are solved. The high reusability of back-end services is realized and the advantages of micro-service architecture are tested in our system.

INVESTIGATIONS OF THE DYNAMICS OF A BISTABLE ELECTROMAGNET WITH IMPROVED CHARACTERISTICS FOR MEDIUM VOLTAGE VACUUM CIRCUIT BREAKERS

Introduction. Currently, for switching medium voltage circuits, vacuum circuit breakers are widely used, which have good arcing properties and high breaking capacity. One of the problems of creating the drive mechanism of such apparatus is the need to ensure the absence of contact welding when a through current of a short circuit of a given duration flows through them, which is achieved due to a certain amount of contact pressure. One of the problems arising in the design of circuit breakers is the need to fix the mechanism with a mechanical lock, which should hold the mechanism securely. This leads to significant specific mechanical loads, which in turn reduces the reliability of the circuit breaker. One way to solve these problems is to create a drive based on monostable or bistable electromagnetic actuators with highly coercive permanent magnets, which provide reliable fixation of the position of the contacts. Purpose. Investigation of the improved design of a bistable electromagnetic actuator based on permanent magnets of a medium voltage vacuum circuit breaker. Methods. Theoretical and experimental research and comparative analysis of existing and developed electromagnetic actuators. Conclusions. A new design of an electromagnetic bistable actuator with reduced overall dimensions is developed and tested. The electromechanical characteristics of the actuator correspond to the technical specifications, which is confirmed by both theoretical and experimental studies. The proposed actuator can be used as a drive mechanism for medium voltage vacuum circuit breakers.

Investigations of the Dynamics of a Bistable Electromagnet with Improved Characteristics for Medium Voltage Vacuum Circuit Breakers

Introduction: Currently, for switching medium voltage circuits, vacuum circuit breakers are widely used, which have good arcing properties and high breaking capacity. One of the problems of creating the drive mechanism of such apparatus is the need to ensure the absence of contact welding when a through current of a short circuit of a given duration flows through them, which is achieved due to a certain amount of contact pressure. One of the problems arising in the design of circuit breakers is the need to fix the mechanism with a mechanical lock, which should hold the mechanism securely. This leads to significant specific mechanical loads, which in turn reduces the reliability of the circuit breaker. One way to solve these problems is to create a drive based on monostable or bistable electromagnetic actuators with highly coercive permanent magnets, which provide reliable fixation of the position of the contacts. Purpose: Investigation of the improved design of a bistable electromagnetic actuator based on permanent magnets of a medium voltage vacuum circuit breaker. Methods. Theoretical and experimental research and comparative analysis of existing and developed electromagnetic actuators. Conclusions: A new design of an electromagnetic bistable actuator with reduced overall dimensions is developed and tested. The electromechanical characteristics of the actuator correspond to the technical specifications, which is confirmed by both theoretical and experimental studies. The proposed actuator can be used as a drive mechanism for medium voltage vacuum circuit breakers.

The impacts of circuit breakers on China's stock market

In this paper, we empirically investigate the impacts of the circuit breaker mechanism installed in the Shanghai Stock Exchange using high-frequency intraday data. We find that trade impediments have liquidity effects. In the presence of circuit breakers, investors' behavior will accelerate the arrival of price limits. We also document significant downward magnet effects for individual stocks and for the market index but find no significant volatility spillover effects.

Improvement of protection relay with a single phase autore-closing mechanism based on artificial neural network

This paper presents a developed logical tripping scheme to improve conventional protection performance. Adaptive single pole auto reclosure (ASPAR) system is proposed that considers, automatically tripping and reclosing of a multi-shot independent pole technique of a circuit breaker at a predetermined sequence, which can be used to boost the synchronization of the power grid under the transient fault conditions. Moreover, the ASPAR can be utilized to enhance the electrical system stability and reliability at the same operating conditions. Based on the three-phase system, the Artificial neural network (ANN) in this work has been done in order to diagnose and detect healthy and faulted phases. The proposed ANN fault classifier method consists of the logic gates, router circuits, timers, and positive and negative sequence analyses circuit. In addition, it is used to give the ability to recognize a fault type, which by training on the sequence angle values and coordination of the transmission line. Three-phase overhead transmission line including the proposed ASPAR is built in MATLA \SIMULINK environment. Thus the performance ANN-fault classified is tested under different fault conditions. Simulation results show that the proposed ASPAR based on ANN is accurate and well performance. Whereas resultant tripping and reclosing signals of ASPAR are successfully provided that enhances the circuit breaker mechanism under these operating condition.