Circuit Breaker Operation Research Articles

Пропускная способность ограничителей перенапряжений в составе вакуумных выключателей постоянного тока

The article presents the results from numerical simulation and experimental investigation of the throughput capacity of Type 0PN-TP-3.0/4-UKhL 3 metal-oxide surge arresters (MOSA) used as part of a high-speed automatic DC vacuum circuit breaker for the maximal voltage equal to 4.1 kV. The vacuum circuit breaker operation principle isbased on forced lymaking the disconnected current to pass through zero by means of arranging opposite discharge of a pre-charged capacitor. A numerical model is proposed, whichhas been implemented in the Matlab 6.5 software package using the Sim Power Systems library. The applicability of the model has been experimentally confirmed in disconnecting a current by a vacuum circuit breaker through simulating a short-circuit fault current with different current growth rates. The investig a tions were carrie doutata heavy-current high-voltage test bench realizing an oscillatory circuit involving a capacitor bank for the maximal voltage of up to 6 kV and the total energy storage capacity of up to 1.8 MJ. The numerical model satisfactorily describes the processes in disconnecting acurrentina DC vacuum circuit breaker with forcedly making the current to cross zero. The model also make sit possible to estimate the amount of energy dissipated in the MOSA unit in disconnecting a short-circuit fault current. Byusing the proposed model itis also possible to estimate the number of parallel-connected MOSAs in disconnecting emergency currents in traction DC power supply networks with an inductance ranging from 5 to 15 mH.

Prediction of synchronous closing time of permanent magnetic actuator for vacuum circuit breaker based on PSO-BP

One of the key points of phase-controlled technology is to predict the circuit breaker's operation time. In this paper, it took control voltage and ambient temperature as the main input variables to forecast the closing time through building backward propagation (BP) neural network model. In view of the high accuracy requirements for the closing time's prediction, it is difficult to meet the requirement by relying solely on the BP neural network. Basing on BP neural network, it uses particle swarm optimization (PSO) algorithm to optimize the model for improving the prediction accuracy. Through calculation and analysis, the PSO-BP algorithm is more accurate than BP neural network in the prediction accuracy, which controls the error within 0.2%. The prediction error meets the requirements of synchronous controlled technology.

Review of different fault detection methods and their impact on pre‐emptive VSC‐HVDC dc protection performance

Multi-terminal voltage-sourced converters (VSC) high-voltage direct current (HVDC) transmission system is expected to play a vital role in future power systems. Compared with ac power transmission, dc transmission is more vulnerable to faults due to low dc-side impedances and sensitive power electronics in the converters. Dc protection issues must be tackled before any multi-terminal VSC-HVDC grid can be built. The multi-terminal VSC-HVDC system is studied in detail using switching models for two-level converters, detailed equivalent models for the modular multi-level converters, detailed hybrid circuit breaker switching models and frequency-dependent phase models for dc cables. Using such high-fidelity system models, a systematic study of HVDC fault protection methodologies in more detail than previous studies is conducted. This is the first comprehensive study that includes pre-emptive circuit breaker operation. The results presented in this study underline the benefits of such a detailed treatment of the breaker, and of considering it as part of a fast power electronics system rather than isolated dc equipment. The study identifies the best existing fault detection method and tests it extensively. In order to further improve post-fault system recovery response, which is a key but often neglected part of previous studies, a novel bump-less transfer control has been implemented in the converters.

Contact Force Monitoring and Its Application in Vacuum Circuit Breakers

Condition monitoring of circuit-breaker (CB) operating mechanisms is one the most important aspects of predictive maintenance. This paper proposes a contact force monitoring scheme for 10 $\sim$ 35-kV vacuum CB. With specially designed force sensors and a signal-processing method, we can accurately find the instants of contact touch and separation. With the indirectly measured contact touch-and-separation instants, we can measure the opening speed, closing speed, and open gap over the travel of each phase. The accuracy of our online monitoring scheme is compared with the conventional offline methods that can directly obtain the instants of contact touch and separation by measuring the connectivity of the contacts. The results show that the accuracy of the scheme proposed in this paper is satisfactory and it can meet the engineering requirements of online condition monitoring of CBs. By introducing a set of new force sensors, some additional information that is useful for overall condition assessment of CB operating mechanism can also be extracted; this will help us to find new ways to improve our CB condition monitoring systems.

Influence of condensed species on thermo-physical properties of LTE and non-LTE SF6–Cu mixture

SF6–Cu mixture is frequently formed in high-voltage circuit breakers due to the electrode erosion and metal vapor diffusion. During the interruption process, the multiphase effect and deviation from local thermal equilibrium (non-LTE assumption) can both affect the thermo-physical of the arc plasma and further influence the performance of circuit breaker. In this paper, thermo-physical properties, namely composition, thermodynamic properties and transport coefficients are calculated for multiphase SF6–Cu mixture with and without LTE assumption. The composition is confirmed by combining classical two-temperature mass action law with phase equilibrium condition deduced from second law of thermodynamics. The thermodynamic properties and transport coefficients are calculated using the multiphase composition result. The influence of condensed species on thermo-physical properties is discussed at different temperature, pressure (0.1–10 atm), non-equilibrium degrees (1–10), and copper molar proportions (0–50%). It is found that the multiphase effect has significant influence on specific enthalpy, specific heat and heavy species thermal conductivity in both LTE and non-LTE SF6–Cu system. This paper provides a more accurate database for computational fluid dynamic calculation.

Grid connected photovoltaic power plants: new aspects in switching procedures with vacuum circuit breakers involved

This study presents vacuum circuit breaker switching investigation on a grid connected photovoltaic power plants. The focal point of this research is to discuss potential overvoltages during various switching operations in terms of the medium-voltage insulation coordination procedure. Influence of the LC filters of solar converters on high-frequency transients was highlighted, with main focus on generation of arc re-strikes and pre-strikes during opening or closing of the vacuum circuit breaker. Scheduled and emergency switching operations were analysed by means of laboratory experiments and Power Systems Computer Aided Design (PSCAD) simulations. Alternative switching sequences were proposed for mitigation of transient overvoltages.

Online Condition Assessment of Interruption Chamber of Gas Circuit Breakers Using Arc Voltage Measurement

As a key element of a power system, a circuit breaker (CB) requires regular maintenance. Intelligent online condition assessment is increasingly becoming a requirement for key items of power plants, including CBs. The interruption chamber, as the most critical part of the CBs, plays an important role in the proper operation of CBs. Online assessment of this part is difficult from a technical perspective due to the high noise level and presence of a transient recovery voltage. This paper proposes a set up for the online measurement of the CB arc voltage during trip/close operations. In addition, a method has been proposed to evaluate the remaining useful lifetime of the interruption chamber based on the measured arc voltage and current. The setup and the proposed approach are verified experimentally.

Small-Scale HVDC Circuit Breaker

Circuit breakers are anticipated for fault isolation in multiterminal HVdc networks. However, there are remaining challenges concerning the circuit breaker topology and operation. The passive oscillation principle circuit breaker is one of the topologies under consideration, the design of which requires examination of the arc characteristics. The design process is therefore presented, with the aim of constructing a small-scale prototype. First, a horizontal nozzle constricted arc setup with a blowing capability is built in order to study the stationary and transient arc characteristics P(g) and τ(g), which are essential for the design of this type of breaker. Second, after their extraction from measurements, these two arc parameters are inserted into a simulation model based on the Mayr-Schwarz arc equation, which predicts an effective breaker operation. Finally, a passive oscillation principle breaker is constructed and successfully tested with both an arbitrary current source and on a scaled voltage source converter network.

Problems in the Application of Low Voltage Circuit Breakers for Gassing Material

Polyoxymethylene (POM) and nylon 66 (PA 66) represent polymer gassing materials as arc extinguishing chamber side plate or shell were widely used in low voltage circuit breaker. During the short-circuit breaking test of the low voltage circuit breaker, the problems such as pressure, temperature, poisonous and harmful gas, etc. were found for gassing material application. In the application of low voltage circuit breaker, the existence of these problems has an effect on the performance of the low voltage circuit breaker and has the potential safety hazard. In this paper, these above problems were analyzed, the models were established, and the suggestions were put forward. That can optimize the application of gassing material in low voltage circuit breaker, and improve the performance of low voltage circuit breaker.

A Hybrid DC Circuit Breaker Combining a Multilevel Converter and Mechanical Contactors: Verification of the Principles of Operation by Experiment and Simulation

SUMMARYThis paper presents a new hybrid dc circuit breaker producing no conducting power loss under normal operating conditions and having the capability to interrupt a large amount of short‐circuiting current within several milliseconds. It consists of two reactors for current limiting and current control, two mechanical contactors, and a multilevel converter based on the cascade connection of multiple full‐bridge dc/dc converter cells. It is characterized by achieving current commutation from the main mechanical contactor to the multilevel converter with fast current control. This results in eliminating auxiliary power semiconductor switches that produce a nonnegligible conducting power loss under normal operating conditions. This paper discusses both principles of operation and control method of the new hybrid dc circuit breaker. Experimental verification is performed by a downscaled system rated at 300 V and 150 A, along with verification by computer simulation.

An Accelerated Single-Pole Trip Scheme for Zone-2 Faults of Distance Relays

This study presents a new accelerated single-pole trip scheme for distance relays zone-2 single-phase-to-ground faults. A novel nonpilot scheme for detecting the remote-end circuit breaker (CB) operation based on measured signals of unfaulted phases is presented. The proposed method is founded on mutual coupling characteristics of different fault stages between faulted and unfaulted phases. Single-pole tripping of the remote-end CB causes variation of induced voltage on unfaulted phases. The current signals due to this variation are utilized as indicators to issue the accelerated single-pole trip command. The algorithm proficiency in various conditions is tested and impacts of different elements, such as fault resistance, fault location, tower configuration, etc., on its performance are analyzed. Implementation of the new accelerated trip method results in dependability improvement, while it has no adverse effect on the protection security. Extensive simulation results confirm that the proposed method is well capable of protecting internal faults and provides a fast, accurate, and reliable protection technique.

A Novel Reclosing Algorithm Considering Turbine-Generator Shaft Torque

Various factors exist that cause torsional interaction, such as subsynchronous resonance and switching effects following electrical disturbances. In particular, successive circuit-breaker operation may amplify the turbine-generator shaft torque under unsuccessful reclosing conditions. Thus, in this paper, we carried out transient stability analysis using the integral square error method and derived the relationship between the shaft torque amplitude and reclosing time through analysis of a 2-degree of freedom system under reclosing into permanent fault condition. In addition, we proposed a novel reclosing algorithm with consideration of transient stability and shaft torque amplitude. The performance of the proposed reclosing method was verified in actual 154 kV and 345 kV Korean study systems using the Electromagnetic Transient Program.

Analysis of the Vacuum Arc Interruption Process in Aviation Intermediate-Frequency Power Supply Systems

In this paper, we present our research into the interruption performance of vacuum circuit breakers in aviation intermediate-frequency (360 Hz to 800 Hz) power supply systems. Intermediate-frequency vacuum arc experiments were carried out in interrupters with a diameter of 41 mm and CuCr50 alloy contact material. The results show that, as the frequency and peak value of the current increase, both the peak value and rise rate of the intermediate-frequency vacuum arc voltage also increase, and the interruption ability decreases. However, compared to the power frequency current at the same value, the erosion of the contacts is weaker over a shorter arc period. When the vacuum arc reignites, metal droplets are emitted from the contacts. The drive force is from the center of the contact to the edge. If the density of the plasmas and metal vapors and the number of the metal droplets reaches a certain level, the arc may break down, which will cause the interruption to fail.

A Medium-Voltage Hybrid DC Circuit Breaker, Part I: Solid-State Main Breaker Based on 15 kV SiC Emitter Turn-OFF Thyristor

This paper discusses the design of a 10 kV and 200 A hybrid dc circuit breaker suitable for the protection of the dc power systems in electric ships. The proposed hybrid dc circuit breaker employs a Thompson coil based ultrafast mechanical switch (MS) with the assistance of two additional solid-state power devices. A low-voltage (80 V) metal-oxide-semiconductor field-effect transistors (MOSFETs)-based commutating switch (CS) is series connected with the MS to realize the zero current turn-OFF of the MS. In this way, the arcing issue with the MS is avoided. A 15 kV SiC emitter turn-OFF thyristor-based main breaker (MB) is parallel connected with the MS and CS branch to interrupt the fault current. A stack of MOVs parallel with the MB are used to clamp the voltage across the hybrid dc circuit breaker during interruption. This paper focuses on the electronic parts of the hybrid dc circuit breaker, and a companion paper will elucidate the principle and operation of the fast acting MS and the overall operation of the hybrid dc circuit breaker. The selection and design of both the high-voltage and low-voltage electronic components in the hybrid dc circuit breaker are presented in this paper. The turn-OFF capability of the MB with and without snubber circuit is experimentally tested, validating its suitability for the hybrid dc circuit breaker application. The CSs' conduction performances are tested up to 200 A, and its current commutating during fault current interruption is also analyzed. Finally, the hybrid dc circuit breaker demonstrated a fast current interruption within 2 ms at 7 kV and 100 A.

Detection of secondary arc extinction for adaptive single phase auto‐reclosing based on local voltage behaviour

This study presents a non-communication based algorithm for detection of secondary arc extinction for adaptive single phase auto-reclosing of transmission lines. The algorithm is based on the behaviour pattern of the faulted phase voltage magnitude (VM) measured at the near end of the line. A prediction function is used to calculate the present VM few milliseconds in advance of its actual measurement. The difference between the actual and calculated values of the faulted phase VM is used as a criterion for detection of secondary arc extinction. A new method is proposed to analyse the arc extinction criterion which does not need a predefined threshold level. The algorithm uses low sampling frequency and is simple and fast. The algorithm can be applied on all transmission line configurations (transposed or untransposed) with different levels of reactive power compensation. The algorithm has been validated using the electromagnetic transient program software tool for simulation studies under many operational and fault cases. The presented test results for 465 cases verify the algorithm performance, which is not affected by the pre-fault line loading, the circuit breaker opening angle, arc type and fault location.

Password Based Distribution Panel and Circuit Breaker Operation for the Safety of Lineman during Maintenance Work

Security is the prime concern in our day to day life while performing any activity. In the current scenario, accidental death of lineman is often read and evidenced. In this direction, a safety measure to safe guard the operator is found very necessary looking into the present working style. The electric lineman safety system is designed to control the control panel doors and circuit breaker by using a password for the safety. Critical electrical accidents to lineman are on the rise during electric line repair may be due to lack of communication and co-ordination between the maintenance staff and electric substation staff. The proposed system provides a solution that ensures safety of lineman. The control to turn ON or OFF the line is maintained by the lineman. The system has an arrangement such that a password is required to operate the doors of the control panel and circuit breaker (ON/OFF). A secured password is requested and received from the control room by the lineman for the point of repair or service. This request is registered and a password is sent to the lineman’s mobile and control panel GSM module for the further work. The password is entered through the matrix keypad which is interfaced to the Arduino Uno microcontroller. The entered password is compared with the password received by the control panel GSM receiver. If the entered password is correct then the circuit breaker ON/OFF and door OPEN/CLOSE feature is enabled for the lineman to take up repair. Any intruder tries to operate the mechanism with the wrong password by three times it will display a message in the LCD display and a message is sent to the control room regarding unauthorized accessing of the system for the safety reasons.

Impulse breakdown characteristics of aged oil impregnated paper

Voltage-time (v-t) characteristic plays an important role during the insulation coordination of a power system. Power transformer is the crucial equipment in the design of a reliable power system. During the operation of a transformer, Oil Impregnated Paper (OIP), the widely used winding insulation of transformer, undergoes significant irreversible aging. Aging alters the dielectric properties of the OIP reducing it's withstand capability. Hence in this work, the impulse v-t characteristic of fresh OIP and 8 years service aged OIP of the same manufacturer are compared. Moreover, when the transformers are directly connected to Gas Insulated Substations (GIS) and during the switching operation of vacuum circuit breakers, OIP is stressed by Very Fast Transient Overvoltage (VFTO). In addition, transformers are subjected to repeated impulses generated during multiple lightning strokes, switching operations of circuit breakers and HVDC converters. Various studies have pointed out the adverse effect of VFTO and repeated impulses on transformer insulation. Therefore, the effects of VFTO and repeated impulses (both LI and VFTO) on the v-t characteristics of fresh and service aged OIP are quantitatively assessed and discussed with reference to the Basic Impulse Insulation Level (BIL) and protection level of the transformer insulation.

Transient Electromagnetic Disturbance Induced on the Ports of Intelligent Component of Electronic Instrument Transformer Due to Switching Operations in 500 kV GIS Substations

Switching operations in gas-insulated switchgear (GIS) substations generate transient electromagnetic fields in the GIS pipes. These fields leak out discontinuities of the GIS and induce electromagnetic disturbance voltages on the cables and ports of secondary circuits. In smart GIS substations, secondary devices especially, such as the intelligent component of electronic instrument transformer, are vulnerable to electromagnetic interference. In this paper, the disturbance voltages induced on the ports of intelligent component of electronic instrument transformer had been measured in three 500-kV GIS substations, respectively. The disturbance was generated either during disconnector (DS) switching operations or circuit breaker (CB) operations. Then, the time-domain and frequency-domain characteristics of the disturbance waveforms have been analyzed. The micro-pulses of disturbance voltages have been extracted from the raw data. The waveform parameters, including peak voltage, rise-time, dominated frequency, and duration, have been calculated by the statistical analysis. The comparison between disturbance during DS switching operations and that of CB operations has been made. Also, the differences and similarities of disturbances between the three GIS substations have been displayed. Furthermore, the differences between measured waveforms and the IEC 61000-4-18 immunity test standard waveform have been discussed.

Arcless opening of direct current circuits in technical systems

Operation of the proposed DC circuit breaker consists in the fact that the closing of the thyristor in the DC power circuit with an inductive load results from opening the auxiliary circuit with a current value several fold less than the load current. The power and auxiliary circuits are connected by means of a current transformer having counter switch windings. After switching, the load is shunted by a diode and does not affect the transition process. Simulations and experimental tests of the DC circuit breaker model showed its performance capability, and the breaker can be used for switching in existing DC high current circuits with inductive loads.

Simulation Analysis for Opening Performance of Medium Voltage Vacuum Circuit Breaker Based on ADAMS and Maxwell

The circuit breakers play a important role in control and protect the power systemand the vacuum circuit breaker has beenwidely used in the field of medium voltage with its excellent opening performance.Virtual prototyping technology is alsobecamemore and more popularin design and optimization of the vacuum circuit breaker. In this paper, the electromagnetic simulation software Ansoft Maxwell is used to analyze the electric repulsion of the circuit breaker in the case of open the rated short circuit breaking current. The 3D model that wasbuilt by CREOis imported into ADAMS. Thenconstraints, contact force, and the electric repulsion forcethat was analysezed in Ansoft Maxwell is added into the 3D model.Therefore, we can carry on the multi-body dynamics simulation to the 3D model. Then We can get the openingperformance of the vacuum circuit breakerin the condition of open circuit rated short circuit breaking current. The simulation results show that the circuit breaker can still meet the performance requirements in the condition of open circuit rated short circuit breaking current.