Hybrid Direct Current Circuit Breaker Research Articles

Simulation study of integrated‐gate‐commutated‐thyristor based superconducting hybrid direct current circuit breaker

AbstractWith the development of a distributed generation, direct current (DC) load and energy‐storage equipment, voltage‐source‐converter‐based medium‐voltage DC systems (VSC‐MVDC) have attracted more attention due to its low power consumption, high reliability, independent power control and so on. However, VSC‐MVDC has the problem of DC fault isolation, which requires the fast‐acting DC circuit‐breakers to isolate faulty lines and ensure low cost. This problem can be solved by coordinating resistive type superconducting‐fault‐current‐limiter (R‐SFCL) and integrated‐gate‐commutated‐thyristor (IGCT) based hybrid circuit breaker. Based on this, IGCT based superconducting DC circuit breaker (SDCCB) is proposed and analysed. Combining R‐SFCL with IGCT could realise large current limiting and interruption and ensure low cost. In addition, the IGCT based hybrid DC circuit breaker (IGCT‐HDCCB) is compared with the traditional insulated gate bipolar transistor (IGBT) based hybrid DC circuit breaker (IGBT‐HDCCB) to evaluate which circuit breaker is more suitable for VSC‐MVDC. The results show that, coordination based on R‐SFCL and SDCCB, the fault current is successfully limited from 17.6 to 2.1 kA, and then interrupted within 3.8 ms. In addition, IGCT‐HDCCB overcomes the disadvantage that IGCT has less interrupting capacity than IGBT, retains the advantage of low cost of IGCT and is more suitable for MVDC system.

Optimal Design Parameters for Hybrid DC Circuit Breakers Using a Multi-Objective Genetic Algorithm

The primary function of hybrid direct current circuit breakers (HCBs) is to quickly interrupt fault currents to protect high-voltage direct current (HVDC) systems. To enhance the reliability and stability of HVDC systems, optimal design of HCBs is required to minimize the peak fault current, interruption time, and recovery time. Therefore, this study develops a multi-objective genetic algorithm (MOGA)-based optimization model to identify the optimal parameters for HCBs. The MOGA model consists of three objective functions that provide trade-offs among reductions in the peak fault current, the interruption time, and the recovery time. The proposed algorithm is verified with a novel HCB topology using inverse current injection techniques. The performance of the HCB topology with the optimal parameters is validated in the MATLAB/Simulink environment. In addition, a comparison study between the optimal design of an HCB using the proposed algorithm and a typical HCB model is presented in this study to show the effectiveness of the proposed optimization method. Our simulation results show that the optimal parameter design of HCBs significantly reduces the magnitude of the peak fault current and operating time, thus maintaining the safe and stable operation of the entire system.

Hybrid DC Circuit Breaker Using a SiC‐Semiconductor Module at 1 kA Interruption

Hybrid direct current circuit breakers (DCCBs) have become prominent because of their low on‐state power dissipation and small arc erosion compared with conventional semiconductor and mechanical circuit breakers (CBs). After a fault occurs in a DC circuit, the current commutates from the mechanical contacts to the semiconductor devices of the hybrid DCCB, and finally, the current is interrupted by the semiconductor devices. Thus, a low turn‐on voltage or a low on‐state resistance of the devices is needed to reduce the commutation time and power dissipation of the current interruption. This paper presents a comparison of DCCB performances metrics, such as the maximum interruption current, power dissipation, and junction temperature, using a silicon carbide metal‐oxide‐field‐effect transistor (SiC‐MOSFET) and silicon insulated‐gate‐bipolar transistor (Si‐IGBT) module. An interruption of 1.1 kA was achieved in 4.3 ms using the SiC‐MOSFET module of which rated current was 444 A. The junction temperature after the interruption was determined to be 275°C, which exceeded the maximum junction temperature of 175°C. In the case of the Si‐IGBT module of which rated current was 1110 A, the maximum interrupting current was limited to 900 A; however, the maximum junction temperature was 41°C. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Improvement of DC Fault Current Limiting and Interrupting Operation of Hybrid DC Circuit Breaker Using Double Quench

In this paper, direct current (DC) fault current limiting and interrupting operation of hybrid DC circuit breaker (DCCB) using double quench, which consists of DCCB, a series resonance circuit, power electronic switch, surge arrestor, two separated current limiting reactor/resistor, and two superconducting elements, were suggested. The suggested hybrid DCCB can perform the interrupting operation after twice or once DC fault current limiting operation according to DC fault current amplitude. To verify the effective operation of the suggested hybrid DCCB, the modeling for the components of DCCB, the surge arrestor, and the SCE was carried out and its DC operational characteristics were analyzed. Through the analysis of the modeling results for the suggested hybrid DCCB, the advantages of hybrid DCCB were discussed.

Development and prospect of direct‐current circuit breaker in China

The direct-current circuit breaker (DCCB) is the most ideal choice for DC fault isolation in DC grids. Despite a late start, China's research and development on the DCCB have made outstanding achievements. This article provides a brief glance of current China's DCCB development status. It begins by sorting out the technical route according to the topology of DCCB. Then it systematically summarises both mechanical and hybrid DCCBs with focussing on the aspects of topology structure and principle, key technology and characteristics, prototype development and application. It is apparent that Chinese scientists and engineers confronted the worldwide problem of large capacity DC breaking, and put forward a comprehensive solution which consists of an innovative topology structure based on coupled negative voltage circuit, breaking throughs on the key technologies such as highly controllable and reliable fault current commutation, millisecond-level ultra-fast and efficient electromagnetic repulsion mechanism, high tolerance and high stability power electronic switch, low residual voltage and fast response energy consumption device, etc. The article states that the world's first set of hybrid high-voltage (HV) DCCB, and the first set of mechanical HV DCCB have been developed. These DCCBs will soon be deployed to the DC grids which have the highest voltage levels therefore require the strongest breaking capacity. These achievements are leading the world in the development and application of DCCB. The article also discusses the overall development trends of DCCB in the areas of new topologies, key technological breakthroughs and application scenarios, etc. These discussions serve as references for DCCB's future technological advancement and its ever-expanding applications.

Non-permanent Pole-to-pole Fault Restoration Strategy for Flexible DC Distribution Network

As the structures of multiple branch lines (MBLs) will be widely applied in the future flexible DC distribution network, there is a urgent need for improving system reliability by tackling the frequent non-permanent pole-to-pole (P-P) fault on distribution lines. A novel fault restoration strategy based on local information is proposed to solve this issue. The strategy firstly splits a double-ended power supply network into two sin-gle-ended power supply networks through the timing difference characteristics of a hybrid direct current circuit breaker (HDC-CB) entering the recloser. Then, a method based on the characteristic of the transient energy of fault current is proposed to screen the faulty branch line in each single-ended power supply network. Also, a four-terminal flexible DC distribution network with MBLs is constructed on PSCAD to demonstrate the efficacy of the proposed strategy. Various factors such as noise, fault location, and DC arc equivalent resistance are considered in the simulation model for testing. Test results prove that the proposed strategy for fault restoration is effective, and features high performance and scalability.

Research on the breaking branch for a hybrid DC circuit breaker in±500 kV voltage‐sourced converter high‐voltage direct current grid

In order to construct the voltage-sourced converter high-voltage direct current grids, the high capacity direct current circuit breakers (DCCBs) are in demand. The hybrid DCCB has been the mainstream proposal, where the high-voltage solid-state switch (HVSS) is the key component for breaking the final fault current. Investigating the current commutation between the breaking branch and energy-absorbing branch, a hybrid DCCB with repositioned current commutation module (CCM) and redesigned HVSS is proposed in this study. By analysing the equivalent circuit of the CCM and HVSS, the detailed transient stages during current interruption procedure have been revealed, and the comparisons of different topologies for HVSS are made in-depth. The repositioned CCM can greatly decrease the transient voltage stress for HVSS and CCM whilst the improved HVSS including metal oxide varistor can maintain better interruption performances. Then the actual prototypes are developed to verify the effectiveness of the improved hybrid DCCB topology. In the end, a 500 kV DCCB is realised based on the proposed HVSS, which can ensure the reliability and convenience of the hybrid DCCB.

Interaction characteristics between multi‐port hybrid DC circuit breaker and MVDC distribution system under diversified working conditions

Due to the progressive penetration and usage of renewable sources and loads based on power electronics, medium voltage direct current (MVDC) distribution system is getting broad attention. Direct current circuit breakers (DCCBs) are of vital importance for the reliability and flexibility of power system. With features of low cost and micro-operating losses, multi-port hybrid DCCB with negative voltage source (NVS) has been proposed by the authors and might be a better choice. To further promote its industry application in MVDC system, interaction characteristics between DCCB and power system are investigated in this study. The structure of multi-port hybrid DCCB is briefly introduced. Then, considering the diversified working conditions, e.g. single fault, multiple faults and switching load current with random direction, the cooperation sequence of components in multi-port DCCB under all these working conditions is proposed, respectively. Then, based on simulation model established in PSCAD/EMTDC, transient current/voltage distribution pattern inside multi-port DCCB and its mechanism are discussed, and simulation results have verified the superiority and effectiveness of multi-port hybrid DCCB with NVS in MVDC system.

A Resonant Hybrid DC Circuit Breaker for Multi-Terminal HVDC Systems

High-voltage direct current (DC) transmission systems and multi-terminal direct current transmission systems are attracting attention for expanding the grid to promote introduction of renewable energy. Fault clearing in DC systems is difficult because there is no zero point of current. Hybrid circuit breakers are suitable for fault clearing in DC systems. Conventional hybrid circuit breakers have a hard-switching path that damages the switch. Hard switching damages the device and produces emissions due to harmonic noise. A novel resonant hybrid DC circuit breaker is proposed in this paper. The proposed circuit breaker reduces the damage to the switching device using soft switching due to the current zero point. The proposed circuit breaker is compared with conventional hybrid circuit breakers using numerical simulations. Interruption times and switching types of circuit breakers were compared. The simulation results of the fault clearing characteristics of the proposed breakers show that the proposed breakers have sufficient performance and are capable of stable reconnections in multi-terminal direct current transmission systems.

Research on Vacuum Arc Commutation Characteristics of a Natural-Commutate Hybrid DC Circuit Breaker

Vacuum arc commutation is an important process in natural-commutate hybrid direct current (DC) circuit breaker (NHCB) interruption, as the duration of vacuum arc commutation will directly affect the arcing time and interrupting time of NHCB. In this paper, the vacuum arc commutation model of NHCB was established by simplifying solid-state switch (SS) and vacuum arc voltage. Through theoretical analysis and experiments, the vacuum arc commutation characteristics of NHCB were studied. The mathematical formula of the effect of main parameters on the duration of vacuum arc commutation is obtained, and the changing law of the influence of the main parameters on the duration of the vacuum arc commutation is explored. The concept of vacuum arc commutation coefficient is proposed, and it is a key parameter that influences the vacuum arc commutation characteristics. The research on the characteristics of vacuum arc commutation can provide theoretical foundation for the structure and parameter optimization of NHCB and other equipment that uses vacuum arc commutation.

Novel Reclosing Strategy Based on Transient Operating Voltage in Pseudobipolar DC System With Mechanical DCCB

To ensure the reliability and flexibility of direct current (dc) system, direct current circuit breakers (DCCBs) are in urgent demand. Compared with solid-state and hybrid DCCBs, mechanical DCCBs have features of low operating losses and investment, showing bright application prospects. Until now, without concern about transient operating voltages (TOV) in the whole dc system, the reclosing of DCCB is still an open problem, and it is the emphasis of this article. First, overview of TOV in typical pseudobipolar dc system is introduced. Then, focused on hardware, electrical characteristic of a novel mechanical DCCB is analyzed, and verification tests are carried out in our laboratory. By taking interaction between the dc system, DCCB, and lines into consideration, distribution patterns of TOV under different faults and its mechanism are revealed. Based on TOV, novel reclosing strategy is proposed for mechanical DCCBs, and case studies are conducted in PSCAD/EMTDC for verification. Remarkable advantages of novel reclosing strategy are: fault type could be identified without operating any component of DCCB after fault current interruption; no risk of reclosing a permanent fault point; an explicit time could be reserved for the dielectric recovery of temporary fault point.

Enhanced Active Resonant DC Circuit Breakers Based on Discharge Closing Switches

Direct current circuit breakers (DCCBs) have become a large research topic and are considered one of the critical components for future DC grids. Proposed DCCB concepts may be grouped into hybrid DCCBs and active resonant DCCBs. In this work, the enhanced active resonant (EAR) DCCB family is introduced. EAR DCCBs combine elements of hybrid and active resonant DCCBs. The EAR DCCB family consists of one unidirectional and six bidirectional concepts. All concepts feature proactive commutation. The main characteristic of the EAR DCCBs is that discharge closing switches are used instead of semiconductors with turn-off capability. Relevant discharge closing switch technology is reviewed, a laboratory prototype is explained, and experimental results are presented to demonstrate the feasibility of the proposed DCCB concepts.

Dielectric strength of electric contacts after short‐duration arc in a hybrid DC circuit breaker

A hybrid direct current circuit breaker consisting of electrical contacts connected in parallel with a silicon carbide metal oxide semiconductor field‐effect transistor semiconductor device is capable of operating with low energy loss and high short‐circuit tolerance. It features a short‐duration arc discharge during current commutation; however, how the arc affects the dielectric strength between the contacts is not yet clear. This study conducts a quantitative evaluation of the dielectric strength after a short‐duration arc commutation. It is shown that the dielectric strength decreases after the arc commutation, and the breakdown electric field decreases as the arc duration increases. These results suggest that the existence of metal vapor and an increase in contact erosion caused by the commutation arc lower the dielectric strength of the electric contacts, in addition to the known effects of temperature rise of the contact surface and the air between contacts. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

A High-Performance and Economical Multiport Hybrid Direct Current Circuit Breaker

Hybrid dc circuit breaker (HCB) is an effective device for interrupting dc fault currents in dc grids. Conventional two-port HCB requires too many insulated gate bipolar transistors (IGBTs) in series in its main breaker, resulting in considerable costs. Recently proposed multiport hybrid dc circuit breakers (multiport HCBs, and the number of ports is greater than or equal to 2) interrupt fault currents on multiple lines using only one shared main breaker, significantly reducing the implementation costs but losing some fault handling capabilities. To overcome these obstacles, we propose a novel high-performance economical multiport hybrid dc circuit breaker (MP-HCB) in this article. The topology and its control method are proposed. Due to the designed ring-connection structure, the proposed MP-HCB can avoid dc bus fault, and thus is more reliable. The electrical stresses of the breaker are theoretically analyzed, and the parameters are determined to make the MP-HCB capable of multiple-line faults. Compared with the typical two-port HCB and the existing multiport HCBs, the proposed MP-HCB can achieve full fault current interruption capability with lower costs. To protect a dc node connecting with three lines, the cost of the semiconductors of the proposed MP-HCB is only 1/3 of the typical two-port HCB and 1/2 of the existing multiport HCB. Finally, the performances of the proposed MP-HCB are verified via a four-terminal HVdc system in power systems computer aided design/ electromagnetic transients including DC (PSCAD/EMTDC).

Analysis and Experiment of a Micro-Loss Multi-Port Hybrid DCCB for MVDC Distribution System

Medium voltage direct current (MVdc) distribution system has numerous advantages over medium voltage alternative current distribution system. However, two shortcomings of the existing hybrid direct current circuit breaker (DCCB) with load current switch, including high construction cost and high operating losses, have constrained the application of existing hybrid DCCBs in MVdc distribution system. To overcome these two shortcomings, a novel multi-port hybrid DCCB with negative voltage source (NVS) has been proposed in this paper. First, the general topology and working principle of the multi-port hybrid DCCB with NVS are presented. Then, focused on the current commutation method and economic performance, comparisons between different hybrid DCCBs have been carried out. The analysis shows that by using multi-port hybrid DCCB with NVS, the construction cost could be reduced dramatically and the operating losses could be reduced to be comparable with alternative current circuit breaker, which are negligible. In the end, to fill the blank of experimental research, based on the topology of multi-port hybrid DCCB with NVS, a prototype with rating voltage of 2 kV has been established, and the test result have verified the multi-port hybrid DCCB with NVS.

No-Load Dielectric Recovery of the Ultra-Fast Vacuum Switch in Hybrid DC Circuit Breaker

The no-load curve of the dielectric recovery strength of the ultra-fast mechanical vacuum switch (MVS) changing with time is the theoretical foundation to optimize the turn-off strategy of the hybrid direct current circuit breaker with load commutation switch. To avoid the shortcomings of the classic synthetic circuit, a novel test circuit is proposed to measure the no-load dielectric recovery curve of the MVS in this paper. In the test circuit, a succession of pulse voltages is automatically applied on the MVS, and multiple breakdowns of the MVS occur in one test. Therefore, the dielectric strength of the MVS at multiple time points is obtained, and the envelope of the applied voltage on the MVS during one test can describe the dielectric recovery curve of the MVS; as a result, the test workload could be reduced dramatically and the measurement is more authentic. By changing test conditions, including the rate of rise of the test voltage and the operating speed of the MVS, no-load dielectric recovery characteristics are studied. The research has shown that the dielectric recovery speed of the MVS is irrelative with the rate of rise of the test voltage and it is directly proportional to the opening speed of the MVS.

A novel HVDC circuit breaker for HVDC application

Hybrid high voltage direct current circuit breakers (DCCBs) are capable of interrupting fault current within a few milliseconds, but this technology has high capital cost, especially in a meshed HVDC grid. To increase the economic competitiveness of hybrid DCCBs, this paper proposes a capacitor commutated dc circuit breaker (CCCB). The CCCB mainly comprises an auxiliary branch with a fast dis-connector in series with semiconductor devices and the main branch with the series connection of a dc capacitor and diode valves. This paper provides a detailed depiction of the CCCB. The topology and operating principles are discussed. The impact of snubber circuits and stray inductances on the commutation process is analyzed. The general sizing method for the main components in the CCCB is detailed. Reclosing to transmission lines with different operating conditions is studied. Several extended topologies are proposed to further reduce the semiconductor cost and on-state operation power loss. The power loss and cost of CCCB are assessed. Extensive simulations on PSCAD/EMTDC verified the dc fault isolation and reclosing of the CCCB.

Requirement analysis of hybrid direct current breaker in multi‐terminal high‐voltage direct current grids

Hybrid direct current circuit breakers (DCCB) are the most adopted solution to clear high DC fault currents in short time. Existing literature does not analyse recently validated commercial breakers. This article provides an overview about hybrid DCCB and a list of criteria to evaluate and compare the performance of existing or new DCCB designs. Additionally, general measures are proposed to assess the suitability of the DCCB in a specific grid situation. Accordingly, the fault current evolution under pole-to-pole faults in different parts of a multi-terminal DC grid is analysed by means of mesh analysis with matrix differential equations. Finally, a grid parameter variation analysis is carried out through PSCAD-EMT simulations to compare the presented DCCB concepts.

Technical Assessment of Hybrid DCCB With Improved Current Commutation Drive Circuit

Current commutation from the load current path to the commutation path is the precondition to interrupt current successfully for hybrid direct current circuit breakers (DCCB). With remarkable current commutation performance, current commutation drive circuit (CCDC), mainly consisting of air-core transformer, fast-closing switch (FCS), and precharged capacitor, is proposed by us. In this paper, to eliminate the operating losses of CCDC and to avoid unrecoverable damage of FCS, CCDC used in hybrid DCCB for current commutation has been improved. Different submodules (SM) of commutation path in hybrid DCCB are analyzed, and experiments have been carried out on a hybrid DCCB prototype. Theoretical analysis and experiment results have shown that no matter which kind of SM is used, improved CCDC can ensure reliable current commutation in hybrid DCCB. In the end, by taking total cost of CCDC into consideration, a novel optimization method is proposed to design the parameters of CCDC. With this optimization method, CCDC for hybrid DCCBs with different rated voltage and current can be designed individually and its cost could be reduced significantly.

Centralised busbar differential and wavelet‐based line protection system for multi‐terminal direct current grids, with practical IEC‐61869‐compliant measurements

This study presents a method for discriminative detection of direct current (DC) faults on voltage source converter-powered multi-terminal high-voltage direct current transmission systems using two fundamental guiding principles, namely instantaneous current-differential and travelling waves. The proposed algorithm utilises local voltage and current measurements from all transmission lines connected to a DC busbar, and current measurement from the DC side of the converter. The scheme operates at a sampling frequency of 96 kHz, which conforms with IEC 61869-9. No long distance communication is involved while measurements and signal exchange within DC substations are enabled by the utilisation of IEC 61850. Performance is assessed firstly through detailed transient simulation, using verified models of modular multi-level converters, hybrid DC circuit breakers and inductive DC-line terminations. Furthermore, practical performance and feasibility of the scheme are evaluated through laboratory testing, using the real-time Opal-RT hardware prototyping platform. Simulation and experimental results demonstrate that the proposed protection algorithm can effectively, and within a very short period of time (i.e. <;1 ms), discriminate between busbar and line faults (internal faults), while remaining stable during external faults. Additionally, it has been demonstrated that IEC 61869-9 is suitable for enabling fast DC protection schemes incorporating travelling waves.