Analysis of multiple-faults of high-voltage circuit breakers based on non-negative matrix decomposition

High-voltage circuit breakers are the core equipment in power networks,and to a certain extent,are related to the safe and reliable operation of power systems.However,their core components are prone to mechanical faults.This study proposes a component separation method to detect multiple mechanical faults in circuit breakers that can achieve online real-time monitoring.First,a model and strategy are presented for obtaining mechanical voiceprint signals from circuit breakers.Subsequently,the component separation method was used to decompose the voiceprint signals of multiple faults into individual component signals.Based on this,the recognition of the features of a single-fault voiceprint signal can be achieved.Finally,multiple faults in high-voltage circuit breakers were identified through an experimental simulation and verification of the circuit breaker voiceprint signals collected from the substation site.The research results indicate that the proposed method exhibits excellent performance for multiple mechanical faults,such as spring structures and loose internal components of circuit breakers.In addition,it provides a reference method for the real-time online monitoring of high-voltage circuit breakers.

Transient Ablation Regime in Circuit Breakers

Nozzle wall ablation caused by high temperature electric arcs is studied in the context of high voltage SF6 circuit breakers. The simplified ablation model used in litterature has been updated to take into account the unsteady state of ablation. Ablation rate and velocity are now calculated by a kinetic model using two layers of transition, between the bulk plasma and the ablating wall. The first layer （Knudsen layer）, right by the wall, is a kinetic layer of a few mean-free path of thickness. The second layer is collision dominated and makes the transition between the kinetic layer and the plasma bulk. With this new coupled algorithm, it is now possible to calculate the temperature distribution inside the wall, as well as more accurate ablation rates.

Study of post-arc residual plasma dissipation process of vacuum circuit breakers based on a 2D particle-in-cell model

In order to get an insight into residual plasma radial motion during the post-arc stage,a twodimensional(2D)cylindrical particle-in-cell(PIC)model is developed.Firstly,influences of a virtual boundary condition on the residual plasma motion are studied.For purpose of validating this 2D cylindrical particle-in-cell model,a comparison between one-dimensional particle-in-cell model is also presented in this paper.Then a study about the influences of the rising rate of transient recovery voltage on the residual plasma radial motion is presented on the basis of the 2D PIC model.

Research on Online Monitoring Methods on SF_(6) Circuit Breakers

To promote the accuracy and application of arcing time measurement for SF_6 circuit breaker in substation,five measurement methods are investigated by two cases experimentally. First,the test results of the five methods for a circuit breaker in different stages of wear and a circuit breaker with a component failure were presented. Then,the time error is analyzed by simulation.Finally,the advantage and disadvantage of these methods are discussed.

Numerical Simulation of Gas Flow During Arcing Process for 252 kV Puffer Circuit Breakers

A numerical simulation model for 252 kV puffer circuit breaker is constructed, by using a proven commercial computational fluid dynamics （CFD） package, PHOENICS. The model takes into account the moving parts in the circuit breaker, turbulence enhanced momentum and energy transport, radiation transport. The arcing process in a SF6 puffer circuit breaker with two hollow contacts is simulated under different conditions, and the simulation results are verified with experimental results. Through simulation, the pressure, temperature and velocity in the arc quenching chamber can be obtained. The simulation model is also capable of predicting the influence of design parameters variations on breaker performance, and can thus help to reduce the number of short-circuit tests during the design stage.

Coordinated Control of DC Circuit Breakers in Multilink HVDC Grids

High voltage DC grids are developing in more terminals and with larger transmission capacity,thus the re-quirements for DC circuit breakers(DCCB)will continue to rise.Conventional methods only use the faulty line DCCB to withstand the fault stress,and therefore this paper presents a coordination method of multiple DCCBs to protect the system.As many adjacent DCCBs are tripped to interrupt the fault current,the fault energy is shared,and the requirement for the faulty line DCCB is reduced.Moreover,the adjacent DCCBs are actively controlled to help system recovery.The primary protection,backup protection,and reclosing logic of multiple DCCBs are studied.Simulations confirm that the proposed control reduces the energy dissipation requirement of faulty line DCCB by approximately 30%-42%,the required current rating for IGBTs is reduced,and the system recovery time is also reduced by 20-40 ms.

Circuit breakers in HVDC systems: state-of-the-art review and future trends

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.

Review on Z-Source Solid State Circuit Breakers for DC Distribution Networks

DC technologies will be essential building blocks for future DC distribution networks.As in any DC system,these networks will face crucial threats imposed by short-circuit DC faults.Protection is thus of great interest,and it will likely rely on DC circuit breakers(DCCBs).Among available configurations,Z-source solid-state circuit breakers(Z-SSCBs)are promising candidates for protecting low and medium-voltage distribution networks,as well as DC equipment due to their structural and control simplicity and low cost.In this paper,start-ofthe-art of Z-SSCBs topologies is reviewed.To set the context,the use of DC technologies for grid integration of renewables,DC power transmission,and the main types of DCCBs to protect DC transmission and distribution corridors are discussed.The Z-SSCB topologies are then classified into unidirectional and bidirectional.Advantages and disadvantages of different configurations are compared and analyzed based on existing research.Finally,a perspective on the future development of Z-SSCBs is discussed and potential challenges are elucidated.

Fluid-chemical modeling of the near-cathode sheath formation process in a high current broken in DC air circuit breaker

When the contacts of a medium-voltage DC air circuit breaker(DCCB) are separated, the energy distribution of the arc is determined by the formation process of the near-electrode sheath. Therefore, the voltage drop through the near-electrode sheath is an important means to build up the arc voltage, which directly determines the current-limiting performance of the DCCB. A numerical model to describe the near-electrode sheath formation process can provide insight into the physical mechanism of the arc formation, and thus provide a method for arc energy regulation. In this work, we establish a two-dimensional axisymmetric time-varying model of a medium-voltage DCCB arc when interrupted by high current based on a fluid-chemical model involving 16 kinds of species and 46 collision reactions. The transient distributions of electron number density, positive and negative ion number density, net space charge density, axial electric field, axial potential between electrodes, and near-cathode sheath are obtained from the numerical model. The computational results show that the electron density in the arc column increases, then decreases, and then stabilizes during the near-cathode sheath formation process, and the arc column's diameter gradually becomes wider. The 11.14 V–12.33 V drops along the17 μm space charge layer away from the cathode(65.5 k V/m–72.5 k V/m) when the current varies from 20 k A–80 k A.The homogeneous external magnetic field has little effect on the distribution of particles in the near-cathode sheath core,but the electron number density at the near-cathode sheath periphery can increase as the magnetic field increases and the homogeneous external magnetic field will lead to arc diffusion. The validity of the numerical model can be proven by comparison with the experiment.

Development and Tests of ZW-126/D2000-40 Vacuum Circuit Breakers with Controlled Switching Technology

A ZW-126/D2000-40 type single-break vacuum circuit breaker(VCB)with controlled switching technology is designed and produced in this paper.The results of type tests based on IEC and GB standards are presented.A 126 kV singlebreak vacuum interrupter(VI)with 3/4 coil axial magnetic field(AMF)contacts is used in the VCB,which can interrupt short currents of 40 kA.The external insulation of the VI is provided by SF_(6) at 0.1 MPa.In order to match the 126 kV single-break VI and controlled switching device,a long-stroke electro-magnetic force actuator(EMFA)with 16 kN closing holding force and 3.5 m/s average opening speed is designed.Moreover,a position tracking controlled switching device based on closed-loop control using the technology of a fuzzy control algorithm and pulse width modulation is applied to the controlled switching device.This device is applied to control the coil current of EMFA and the electromagnetic force,so as to control the EMFA to follow the ideal position curve.The type tests of 126 kV VCB are all passed according to the IEC62271-100 and GB1984-2014,including dielectric tests,basic short-circuit tests,shortline fault tests,out-of-phase tests,etc.The strong capacitive current breaking capacity and mechanical strength of the VCB are proved by the capacitive current switching test of class C2,electrical endurance test of class E2 and mechanical endurance test of class M2.The electromagnetic compatibility(EMC)tests are passed according to the IEC61000-4.The controlled switching test of capacitive current was successful according to IEC62271-302 and GB/T30846-2014,and the controlled switching accuracy is less than±0.5 ms.The test results show that the VCB has excellent performance,which has broad application prospects in special occasions at a 126 kV voltage level,such as a switching capacitor and no-load transformer,etc.

Protection of large partitioned MTDC Networks Using DC-DC converters and circuit breakers

This paper proposes a DC fault protection strategy for large multi-terminal HVDC(MTDC)network where MMC based DC-DC converter is configured at strategic locations to allow the large MTDC network to be operated interconnected but partitioned into islanded DC network zones following faults.Each DC network zone is protected using either AC circuit breakers coordinated with DC switches or slow mechanical type DC circuit breakers to minimize the capital cost.In case of a DC fault event,DC-DC converters which have inherent DC fault isolation capability provide‘firewall’between the faulty and healthy zones such that the faulty DC network zone can be quickly isolated from the remaining of the MTDC network to allow the healthy DC network zones to remain operational.The validity of the proposed protection arrangement is confirmed using MATLAB/SIMULINK simulations.

Novel Fast Operating Moving Coil Actuator with Compensation Coil for HVDC Circuit Breakers

DC circuit breakers are major enabling components for multi-terminal HVDC systems.Their key design targets are operating speed and efficiency.This paper proposes a novel moving coil actuator using a compensation coil topology to operate mechanical circuit breakers.This topology aims to significantly improve the magnetic field saturation and reduce the system inductance,so that the operating speed is increased.Four possible connection methods for the compensation coils are proposed and analyzed using finite element modeling,ensuing simulation results are compared and discussed.The operating speed of the moving coil actuator with compensation coils is significantly improved compared with the original moving coil actuator.The moving coil actuator with compensation coils can open a distance of 5 mm within 2.8 ms and the peak efficiency is 47%.

Circuit Model with Current Interruption for Hybrid High Voltage DC Circuit Breakers to Achieve Precise Current Experiments

The current interruption test based on an LC resonance circuit for hybrid DC circuit breakers(HVDC CBs)is widely employed to characterize the current interruption capability of CBs.In order to ensure a high-fidelity replica of the fault current in a high voltage application,this paper first proposes an equivalent model of the test circuit,where not only parasitic resistances but also the threshold voltages and on-state resistances of various semiconductor devices are considered.Moreover,the analytical formula of the test current is derived by including the working principle of the HVDC CB.Secondly,the parameter extraction method,which combines finite element analysis and measurements by an impedance analyzer,is given in this paper.The extracted result implies that,in current interruption transients,equivalent resistances of 500 kV CB are as large as 535 mS,which have a significant influence on current waveforms.Thirdly,the 34 kV/25 kA current interruption test for the 500 kV CB is conducted.The measured results are proved to be consistent with the analytical results obtained from the proposed model,and the relative error is less than 2%.

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.

Influence of the axial magnetic field on sheath development after current zero in a vacuum circuit breaker

After current zero,which is the moment when the vacuum circuit breaker interrupts a vacuum arc,sheath development is the first process in the dielectric recovery process.An axial magnetic field（AMF） is widely used in the vacuum circuit breaker when the high-current vacuum arc is interrupted.Therefore,it is very important to study the influence of different AMF amplitudes on the sheath development.The objective of this paper is to study the influence of different AMF amplitudes on the sheath development from a micro perspective.Thus,the particle in cell-Monte Carlo collisions（PIC-MCC） method was adopted to develop the sheath development model.We compared the simulation results with the experimental results and then validated the simulation.We also obtained the speed of the sheath development and the energy density of the ions under different AMF amplitudes.The results showed mat the larger the AMF amplitudes are,the faster the sheath develops and the lower the ion energy density is,meaning the breakdown is correspondingly more difficult.

Numerical Study on Arc Plasma Behavior During Arc Commutation Process in Direct Current Circuit Breaker

This paper focuses on the numerical investigation of arc plasma behavior during arc commutation process in a medium-voltage direct current circuit breaker （DCCB） contact system. A three-dimensional magneto-hydrodynamic （MHD） model of air arc plasma in the contact system of a DCCB is developed, based on commercial software FLUENT. Coupled electromagnetic and gas dynamic interactions are considered as usual, and a thin layer of nonlinear electrical resistance elements is used to represent the voltage drop of plasma sheath and the formation of new arc root. The distributions of pressure, temperature, gas flow and current density of arc plasma in arc region are calculated. The simulation results indicate that the pressure distribution related to the contact system has a strong effect on the arc commutation process, arising from the change of electrical conductivity in the arc root region. In DCCB contact system, the pressure of arc root region will be concentrated and higher if the space above the moving contact is enclosed, which is not good for arc root commutation. However, when the region is opened, the pressure distribution would be lower and more evenly, which is favorable for the arc root commutation.

Study on the Mathematical Model of Dielectric Recovery Characteristics in High Voltage SF6 Circuit Breaker

According to the stream theory, this paper proposes a mathematical model of the dielectric recovery characteristic based on the two-temperature ionization equilibrium equation. Taking the dynamic variation of charged particle＇s ionization and attachment into account, this model can be used in collaboration with the Coulomb collision model, which gives the relationship of the heavy particle temperature and electron temperature to calculate the electron density and temperature under different pressure and electric field conditions, so as to deliver the breakdown electric field strength under different pressure conditions. Meanwhile an experiment loop of the circuit breaker has been built to measure the breakdown voltage. It is shown that calculated results are in conformity with experiment results on the whole while results based on the stream criterion are larger than experiment results. This indicates that the mathematical model proposed here is more accurate for calculating the dielectric recovery characteristic, it is derived from the stream model with some improvement and refinement and has great significance for increasing the simulation accuracy of circuit breaker＇s interruption characteristic.

The Voltage Distribution Characteristics of a Hybrid Circuit Breaker During High Current Interruption

Hybrid circuit breaker （HCB） technology based on a vacuum interrupter and a SF6 interrupter in series has become a new research direction because of the low-carbon requirements for high voltage switches. The vacuum interrupter has an excellent ability to deal with the steep rising part of the transient recovery voltage （TRV）, while the SF6 interrupter can withstand the peak part of the voltage easily. An HCB can take advantage of the interrupters in the current interruption process. In this study, an HCB model based on the vacuum ion diffusion equations, ion density equation, and modified Cassie-Mayr arc equation is explored. A simulation platform is constructed by using a set of software called the alternative transient program （ATP）. An HCB prototype is also designed, and the short circuit current is interrupted by the HCB under different action sequences of contacts. The voltage distribution of the HCB is analyzed through simulations and tests. The results demonstrate that if the vacuum interrupter withstands the initial TRV and interrupts the post-arc current first, then the recovery speed of the dielectric strength of the SF6 interrupter will be fast. The voltage distribution between two interrupters is determined by their post-arc resistance, which happens after current-zero, and subsequently, it is determined by the capacitive impedance after the post-arc current decays to zero.

Research on arc root stagnation when small current is interrupted in self-excited circuit breaker

The self-excited DC air circuit breaker(SE-DCCB)has been widely used in urban rail transit due to its excellent stability.It can realize forward and reverse interruption,but has difficulty interrupting small currents due to the phenomenon of arc root sticking at the entrance of the arc chamber in the splitting process,which is known as arc root stagnation.A coupling model of the self-excited magnetic field and magnetohydrodynamics is established for the SE-DCCB with the traditional structure.The magnetic field,temperature and airflow distribution in the arc chamber are investigated with an interrupting current of 150 A.The simulation results show that the direction and magnitude of the magnetic blowout force are the dominant factors in the arc root stagnation.The local high temperature of the arc chamber due to arc root stagnation increases the obstruction effect of the airflow vortex on the arc root movement,which significantly increases the arc duration time of small current interruption.Based on the research,the structure of the magnetic conductance plate of the actual product is improved,which can improve the direction and magnitude of the magnetic blowout force at the arc root so as to restrain the development of the airflow vortex effectively and solve the problem of arc root stagnation when the small current is interrupted.The simulation results show that the circuit breaker with improved structure has a better performance for a small current interruption range from 100 A to 350 A.

Influence of Shock Wave on Turbulence in SF_6 Puffer Circuit Breaker

Influence of the shock wave on the turbulence in a supersonic nozzle was investigated for a SF6 puffer circuit breaker interruption process. Turbulence is enlarged through the shock wave. Baroclinic generation of vortex causes flow separation and broadening of the arc cross section. V-I characteristics are slightly modified due to the shock wave＇s influence.