Development Of Circuit Breakers Research Articles

Parameter Optimization Design of the Commutation Circuit of a Hybrid DC-Current-Limiting Circuit Breaker

Aimed at the optimization design of the parameters of the commutation circuit of a hybrid DC-current-limiting circuit breaker (HDCCLCB), a parameter selection model considering the short-time withstand of the thyristor and the volume of the commutation circuit is proposed by simplifying the object, and the commutation circuit parameters were preliminarily obtained. In order to verify the correctness of the method of selecting the commutation circuit parameters, the circuit simulation model of the HDCCLCB was built. The experimental platform was built, and the breaking experiment was completed under the fault condition with the current rising rate of 20 A/μs. The correctness of the simulation model and parameter design method was verified by comparing the circuit model simulation results with the experimental results. In order to further optimize the parameters of the commutation circuit, a mathematical model for optimization design was established. Taking the maximum critical breakdown voltage under unit capacitance energy as the objective function, the arcing time before commutating and the current-limiting inductance and capacitance are enumerated to obtain the optimized commutation circuit parameters. By comparing this result with the result of the preliminary design, the objective function is improved by 20.7%, laying a solid foundation for further research and the development of current-limiting circuit breakers for medium-voltage DC systems.

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.

Design and Study of the Key Characteristics of a New DC Vacuum Interrupter With a High Peak and Low Residual Magnetic Field

With the rapid development of multiterminal high-voltage direct current (HVdc) transmission systems, the research and development of high-speed and stable high-voltage dc circuit breakers have received attention. Among them, mechanical dc circuit breakers based on manual zero-crossing dc breaking technology have been applied in practical projects, owing to their small size, low on-state loss, and low price. However, this method adds a high-frequency current, which deteriorates the magnetic field between the poles of the interrupter when the arc is broken. Therefore, the development of HVdc circuit breakers that maintain high peak magnetic fields and low residual magnetic fields at high frequencies has become the key to the development of multiterminal HVdc transmission. To solve this problem, this article proposes a new interrupter for a vacuum dc circuit breaker based on artificial zero-crossing technology and studies its key characteristics, such as temperature rise, electromagnetic field, and arc column plasma distribution characteristics. The results reveal that the new interrupter proposed in this article has a low-temperature rise, uniformly distributed electric field, high peak value and low remanence of the longitudinal magnetic field, and uniformly distributed plasma in the arc column, and exhibits arc diffusion. Its ability to cope with high-frequency current is significantly higher than that of the traditional cup-shaped axial magnetic field (AMF) contact system interrupter, which is conducive to the high-speed and stable breaking of the interrupter.

Dual-Circuit-Based Test Bench Design for HVDC Circuit Breaker Verification

High-voltage direct current (HVDC) circuit breaker development and deployment strongly depend on the testing process, which ensures that the HVDC circuit breakers will satisfy design requirements. This article presents an HVDC circuit breaker test bench circuit configuration that can provide controllable large output currents to simulate different fault conditions for the current breaking test and high output voltage for the dielectric withstand test. The current breaking test circuit is based on multiple cascaded power converters connected in parallel to provide the necessary output current capability. Each cascaded power converter is composed of multiple cells that are operated by a phase-shifted pulsewidth-modulated signal for greater controllability and higher quality of the output waveform. The dielectric withstand test circuit is a simple high-voltage source with a low power rating that can also be used to charge the test bench and the internal circuitry of the circuit breaker that is to be tested. The proposed test bench ensures that fault conditions can be replicated accurately and offers greater flexibility by being able to test mechanical, semiconductor-based, or hybrid HVDC circuit breakers with different current and voltage ratings on the same hardware without any changes. The idea and the operating principle of the proposed test bench are verified experimentally on a downscaled system that consists of three cascaded power converters connected in parallel with three cells per cascaded power converter and with a total equivalent switching frequency of 92.5 kHz.

Recovery of Withstanding Voltage After Direct Current Interruption Using Vacuum Circuit Breakers

The recovery characteristics of the withstanding voltage of a vacuum gap are crucial for the development of direct circuit breakers with mechanical switches. In the active-current-injection-type dc circuit breakers, a negative voltage, i.e., a voltage of polarity opposite to that of the interrupting current, is initially applied after current zero caused by the energy stored in the active-current-injection branch. Subsequently, the recovery voltage obtains the same polarity as the interrupting current, namely, it becomes positive as the capacitance around the mechanical switch is charged. In this study, the recovery characteristics of the withstanding voltage for the negative and positive polarity are measured by applying impulse voltage after the current zero of dc interruption simulating current. The recovery of the withstanding voltage for a positive impulse takes a longer time than that of the negative impulse. The recovery of the positive withstanding voltage is determined by the decrease in the temperature of the microprojections on the cathode spot edges. The postarc current analysis shows that the postarc plasma decays with time according to the power law in the time range of 1–50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula> after current zero. Under the dc interruptions, where the current decreasing ratio increases, the residual plasma density after current zero tends to be higher than that under ac interruptions.

Aging Characteristics of Contact Electrodes of Low Voltage DC Switches

With the present state of the direct current (DC) distribution market, securing the safety of the DC distribution system is emerging as a major issue. Like AC distribution systems, DC switches and circuit breakers are one of the main means to ensure safety. However, in the DC system, since there is no current zero point in the load current, the phenomenon occurring when the circuit is cut off is different from that of the AC system, so technical research is required to cope with this. In this study, the aging characteristics of the contact electrode of a 400 V class low voltage DC (LVDC) switch is studied for the development of wall-mount switches or circuit breakers for residential houses. As an arc extinguishing method to break DC load current, a prototype experimental circuit breaker that uses a magnetic extinguishing method that is effective for blocking low voltage low power DC is invented, and an automated experiment system is established. The DC switch test repeats the operation of turning it on and off 13,000 times, and continuously evaluates the performance of the electric contacts by calculating the voltage drop between the electrode contacts and the corresponding Ohmic resistance value when conducting every 500 times. This paper tests six contact materials to compare the aging characteristics of them by evaluating contact resistance during the test period. AW18-Cu composite material showed the most stable and excellent contact performance for LVDC switches during the entire test operation period.

A 15-kA Solid-State Circuit Breaker Research and Development for the Switch Network Unit of the EAST Tokamak

This article describes the research, development, and testing of a 15-kA solid-state circuit breaker (SSCB) prototype applied to the switch network unit (SNU) of the Experimental Advanced Superconducting Tokamak (EAST). The circuit scheme composed of parallel connected integrated gate-commutated thyristors (IGCTs) and the diode bridge to realize bidirectional breaker ability is presented first. In addition, the stray inductances of the bus bars and the heat sinks for the current sharing of each IGCT are also considered in detail. Through ANSYS Q3D parameters extraction, the influence of structure stray parameters on the current sharing of power device in parallel is analyzed. Finally, the operation performance of the SSCB has been successfully tested up to the rated current of 15 kA and the maximum interruption voltage of about 2.0 kV, these experiment results verified the current sharing of the parallel-connected devices and the reliability of the SSCB during current conduction and current commutation processes.

Generate Various Parameters Of Trv Envelope Synthetic Test Circuit

The most basic transient a circuit breaker needs to suffer during its activity is the transient recovery voltage (TRV), started by the electric force system as a characteristic response on flow interference. To test high voltage CBs, direct testing utilizing the force system or short out alternators are not practical. The testing of high voltage Circuit Breakers (CBs) of bigger limit requires huge limit of testing station. An equal infusion of short out current and transient voltage to medium and high voltage circuit breaker (CB) by a synthetic model is examined. Transient recovery voltage is made by a capacitor bank and is applied to CB. An optical set off spark gap has been utilized to interrupt short circuit and to introduce of transient recovery voltage that is applied across the contacts of circuit breaker. Transient recovery voltage examination can never be done totally, as the advancement of circuit breaker development and organization configuration goes on. The most widely recognized way to deal with TRV examination is concerning the supposed planned TRV, in which a suspicion of dismissing association between circuit breaker itself and the innate system recovery voltage is being made. Notwithstanding, it actually is by all accounts qualified to examine what circuit breaker means for transient recovery voltage. An ideal grouping to open/close of reinforcement test article and helper circuit breakers inside suitable chance to infuse of recovery voltage. The impact of reactance of inductive flaw current limiter just as distance to blame in short line issue condition on pace of ascent of recovery voltage. A 4-boundaries TRV synthetic test circuit dependent on equal current infusion technique is planned and mimicked for testing 145kV rating circuit-breakers according to new TRV prerequisites given in IEC 62271-100.

A Review of Solid-State Circuit Breakers

Although conventional electromechanical circuit breakers have a proven record as effective and reliable devices for circuit protection, emerging power distribution technologies and architectures, such as dc microgrids, require improved interruption performance characteristics (e.g., faster switching speed). The need for faster switching operation, in combination with the latest developments of advanced power semiconductor technologies, has spurred an increase in the research and development in the area of solid-state circuit breakers. This article provides a comprehensive review of various solid-state circuit breaker technologies that have been reported in the literature during recent years. First, we categorize solid-state circuit breakers based on key features and subsystems, including power semiconductor devices, main circuit topologies, voltage clamping methods, gate drivers, fault detection methods, and commutation methods for power semiconductor devices. Second, we discuss the various challenges associated with the design of solid-state circuit breakers from the perspective of generic applications and provide a comparison of several solid-state breaker technologies based on key metrics. Finally, we provide a useful framework and point of reference for future development of solid-state circuit breakers for many emerging power distribution applications.

HVDC Circuit Breaker Development and Applications in VSC-HVDC Transmission Project

High voltage direct current (HVDC), especially voltage source based HVDC (VSC-HVDC), transmission technology has been expanding in recent decades. HVDC circuit breaker therefore attracts significant interest due to its abilities of current interruption and fault isolation. This paper aims to present the technical development, specifically the topology, control and protection technology and test technology, of HVDC circuit breaker and its applications in VSC-HVDC transmission project. The project background, system configurations, and circuit breaker topology are described for each project. Based on current circuit breaker development and applications, the challenges and associated future development are also presented.

Генераторные выключатели для атомных электростанций

A comparative analysis of the characteristics of foreign and domestic generator circuit breakers is carried out. The necessity of developing a domestic generator circuit breaker for newly constructed nuclear power plants with a power unit capacity of over 1200 MW is shown. The most promising solution is the development of hybrid generator circuit breakers using main contacts, vacuum circuit breakers and controlled arresters. The scheme and operation of elements of hybrid circuit breakers in modes of shutdown of three
phase short
circuit current is resulted. The developed mathematical model of hybrid breakers consisting of generator, busbar and transformer for power plant and given transients disable the short
circuit current in different modes. It is proposed to develop hybrid circuit breakers to replace oil and air circuit breakers at the stages of modernization of nuclear power plants, and in the new construction it is advisable to use generator circuit breakers, as a prototype of which the gas-insulated device developed by ABB is given. Basic electrical formulas for estimation of the switching capacity of the circuit breaker of the generator in the amplitude of the current gap three
phase short
circuit current, degree of asymmetry, amplitude and rate of rise of transient recovery voltage formulated.&nbsp

Determining the Time Constant of Arcs at Arbitrary Current Levels

For the development and optimization of gas circuit breakers and switchgear, a detailed understanding of the arc related processes is of great importance. Ideally, analytical or numerical models with predicitive capability can be found and used during the design process preceding costly and time-consuming experiments.In the present contribution, we report on a novel measurement and evaluation technique to determine the thermal arc time constant ("thermal inertia") that is commonly used in simple black-box models to describe the arc's dynamical properties. The method is introduced and applied to example arcs under varying blow gas conditions in air.

Structure improvement of a 126 kV vacuum circuit breaker using electromagnetic-thermal field coupling simulation

Overheating limits the development of high voltage vacuum circuit breakers (HVVCB) toward large current and compact size. In this paper, an electromagnetic-thermal simulation model is proposed to investigate the thermal characteristics of a 126 kV/40 kA HVVCB. This model is first validated using experimental data. Then it is used to evaluate the thermal performance of the HVVCB with the 2/3 coil-type and horseshoe-type electrodes, respectively. The comparison results showed that the resistance and temperature of the horseshoe-type electrode are much lower than those of the 2/3 coil-type electrodes. The temperature rise in the HVVCB with the horse-type electrodes is also much lower than that in the HVVCB with the 2/3 coil-type electrode. Based on the analysis, a new structure of the HVVCB is proposed by replacing the spring finger connection between the static conductive rod and its conductive support with a fixed connection. The temperature distribution in the new structure and conventional structure is analyzed and compared. The results showed that the temperature reduction at the upper end of the connection is about 23 °C and at the contact surfaces of the two electrodes is about 20 °C in the HVVCB at a current of 2500 A.

Research on Key Technical Parameters of 1100kV Live Tank Circuit Breaker for UHVDC Converter Station

Many of UHVDC transmission projects planned and under construction are hierarchical connected to 500kV and 1000kV AC grid in China. Live tank circuit breakers are selected for switching 1000kV filters. During the development of 1100kV live tank circuit breakers, the closing inrush current and transient recovery voltage are key factors for structure of extinguishing chamber of circuit breakers. In this paper, the above factors are analyzed by simulation, and key technical parameters of 1100kV live tank circuit breakers for UHVDC converter station are proposed.

Analysis of Instability Phenomena at Current Interruption in Vacuum Arc Discharge Compared With Silver or Copper Electrode

Vacuum circuit breakers have an issue of instability arc current and chopping phenomena when the current is cut off from the circuit. To clarify the effect of the instability low-current vacuum arc for circuit breaker development, the instability mechanism of low-current vacuum arc for various parameters was proposed to verify consequent affecting circuit breaker capacity in this paper. This paper used the cathode spot model neglect the transition region between the collisionless sheath and collisional plasma region. The eight equations were used for solving the dependent variable of plasma parameters for both silver and copper electrode materials. The low ionization was supposed in the cathode spot model. The results showed that the changes in the work function and ion current fraction at ambient temperature did not have the main influence on the arc stability limit current both in the silver electrode and copper electrode. On the contrary, the changes in the heat conductivity at ambient temperature affecting the arc stability limit current significantly both in the silver and copper electrodes. Furthermore, the results were found out that the cathode spot can be confirmed unstable current phenomena when the current below 19 A for copper cathode and below 19.4 A for the silver cathode. These phenomena can be explained that the reversed electrons flow from the plasma side to sheath region affecting the electric field at cathode spot become negative zone; thus, the starting noise on the current trace appears before chopping current.

Testing Metal–Oxide Varistors for HVDC Breaker Application

There is growing interest in changing the power grid infrastructure. It is increasingly important to transport a large amount of renewable energy over long distances. To minimize losses, meshed dc-grids are needed but require the development of dc circuit breakers. Without it, a meshed grid cannot be operated. Actually different concepts of dc breakers exist. The majority of them include an energy absorbing element. In ac grids, metal-oxide varistors (MOVs) absorb high energies. However, clarification is needed whether commercial available MOVs are able to handle the energy stresses that arise during dc switching operations. To investigate the energy handling capabilities of conventional metal-oxide material, an endurance test setup has been developed. In this setup, MOV specimens are stressed by repetitive impulse current injections while being permanently connected to dc voltage. This study reports on the endurance behavior of MOV submitted to >10 000 impulse energy injections with 60-100 J/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . Large differences are observed for MOVs from different manufacturers. Temperature and superimposing the impulses by a constant dc voltage are two parameters of less impact. Two types of MOV showed moderate changes of their electrical properties after >10 000 impulses and would be suitable for dc breaker application.

Extending the Application Field of Vacuum Circuit Breakers to Generators for Capacities up to 400 MW

The progress that has been achieved in the development and manufacture of vacuum circuit breakers opens the possibility of using them for a wider range of applications at power plants, including as generator circuit breakers. Such characteristics of modern vacuum circuit breakers as increased breaking capacity and high switching life are factors that make them closer in competitiveness to SF6 circuit breakers for generators with capacities up to 400 MW. The article considers problem aspects relating to clearing of short-circuit faults in the generator voltage circuits and interruption of out-of-phase making currents and no-load currents of generator transformers. Conditions leading to a longer period of time to the moment at which the switched current crosses zero are considered. It is pointed out that, unlike the IEC/IEEE Standard 62271-37-013, GOST (State Standard) R 52565-2006 does not specify the requirements for generator circuit breakers in full. The article gives the voltage drop values across the arc for different design versions of vacuum circuit breaker contacts and shows the effect the arc in a vacuum circuit breaker has on the time delay to the moment at which the current crosses zero. The standardized parameters of transient recovery voltage across the generator circuit breaker contacts are estimated along with the contact gap electric strength recovery rates ensured by modern arc quenching chambers. The switching overvoltages arising when vacuum circuit breakers interrupt short-circuit currents and no-load currents of generator transformers are analyzed. The article considers the most probable factors causing the occurrence of switching overvoltages, including current chopping, repeated breakdowns of the circuit breaker contact gap, and virtual current chopping. It is found that, unlike repeated breakdowns and virtual current chopping, an actual current chopping does not give rise to dangerous switching overvoltages. The article also determines the vacuum circuit breaker application field boundaries in which dangerous switching overvoltages may occur that would require additional measures for limiting them.

Experiment and CFD simulation of exhaust tube in highvoltage circuit breaker

In a high-voltage circuit breaker, the exhaust tube connects the arc zone with the exhaust volume. During the arc interruption process, the exhaust tube transports the hot gas from the arc interruption zone to the exhaust volume through its distributed holes. The design of a high performance exhaust tube in the circuit breaker development aims for well controlled hot gas evacuation mass flow and pressure waves. In this paper, the exhaust tube behaviour is investigated using Computational Fluid Dynamics (CFD). To verify the CFD simulation, a basic experimental study with pressure measurements at different positions of the exhaust tube is performed. Further, the design parameters influencing the exhaust tube behaviour and circuit breaker performance are investigated and discussed.

Dynamic Dielectric Recovery Synergy of Hybrid Circuit Breaker With CO2 Gas and Vacuum Interrupters in Series

This paper investigates the dynamic dielectric recovery synergy (DDRS) of hybrid circuit breakers (HCBs) with CO2 gas and vacuum gaps in series. The interaction between the vacuum arc and CO2 gas arc is simulated by the continuous transient arc model and Mayr arc model. The simulation results indicate that the extra methods, for example, dividing capacitors, are needed to obtain optimal DDRS of HCB. The prototype of HCB and the test circuit are established. The influence of the coordination of arcing time, dividing capacitors, and the CO2 gas pressures on the transient recovery voltage (TRV) distribution and the breaking capacity is investigated. The differences of HCBs with SF6 gas and CO2 gas are also compared. According to the results, favorable DDRS in HCB can be obtained in the condition that the vacuum gap endures the initial TRV while the following major TRV distribution is mainly depended on the dynamic dielectric in CO2 gas gap. However, the dynamic dielectric recovery of CO2 gas gap is limited by the structure of rotating arc CO2 gas interrupter in this paper. In the future, the interruption capacity of HCB based on CO2 gas can be improved by synergy control, as the development of CO2 gas circuit breakers.

INVESTIGATION OF MECHANICAL STRESSES IN THE DRIVE SHAFT OF MV VACUUM CIRCUIT BREAKER

Introduction. In the last 10-15 years a dominant position in the market of medium voltage circuit breakers, vacuum circuit breakers have taken in which as an actuator mono- or bistable actuators with permanent magnets are used. Such circuit breakers are characterized by simplicity of design, high reliability, require preventive maintenance for many years. Development, research and improvement of vacuum circuit breakers are carried out at the Department for Electrical Apparatus, National Technical University «Kharkiv Polytechnic Institute». While working on the circuit breakers, developers have to deal with two related objectives – electrical and mechanical. This paper considers the solution of one of these problems – calculation of mechanical forces in the drive shaft of the vacuum circuit breaker in static and dynamic modes. This work was preceded by the failure of the results of measurements of the prototype circuit breakers’ contacts. Measurements have shown that these values do not match the expected values (there were less than the value of 0.8 to 1 mm). The assumption about the reasons for this discrepancy needed to be detailed checked. The results of the work done are presented in this paper. Purpose. Investigation of static and dynamic mechanical stresses and strains in the drive shaft of the vacuum circuit breaker mechanism to determine its characteristics and material selection. Methods. The investigation of mechanical processes is performed by the finite element method in the COMSOL software package. Results. We obtain the static and dynamic characteristics of the circuit breaker drive shaft: deformations, reaction forces, stresses. These characteristics made it possible to determine the actual course of the contacts, select shaft material and calculate the forces acting on the bearings. Conclusions. It is shown that the contact velocity and contact pressure are different from the theoretical value due to the deformation of the shaft. The forces acting on the thrust bearings dynamically are by 16-39% higher than the static ones. It is assumed that further refinement of the mathematical model takes into account the traction insulators and housing, as well as dynamics of the circuit breaker.