All posters are displayed during the two conference days and can be viewed anytime. The poster session & time here is only used for programming & information purpose.
Integrated gate commutated thyristor (IGCT) has attracted many researchers’ attention in the field of DC circuit breakers application, due to its inherent low on-state loss. The first 6-inch 4.5 kV/ 10kA asymmetrical IGCT in the world has been developed for the single pulse turn-off applications, through optimization of the silicon concentration and transparent anode doping profile on the basis of the 4-inch IGCT technology platform. In this paper we presents the measurement results of the newly developed symmetrical IGCT during conduction and turn-off operations. The on-state voltage drop of this IGCT was achieved the lowest type value of 1.6V at 8kA &125°C. Furthermore, by using matching the new gate unit with the lower stray inductance, the turn-off capability of this IGCT is more than 10 kA. An efficient optimization design of the GCT N-base structure led to no voltage oscillation during turn-off current tail in the test circuit of DC breakers application. This new device will contribute to further improved performance and reliability of the IGCT DC hybrid circuit breaker.
Chen Yongmin, currently is a senior engineer at CRRC. He earned his B.S. from Hunan City University in 2007, and M.S. degree from Central South University in 2010. Since then he joined CRRC Ltd., and has been constantly researching and developing IGCT devices.
In this paper, live detection for the partial discharge of the circuit breakers of an AC filter with abnormal closing under the closing action state and the post-closing operation state are carried out respectively, to timely diagnose the defection of intermittent partial discharge of preinsertion resistors for circuit breakers. The dynamic resistance method is applied to match the live detection results, and the detection method for intermittent partial discharge defects of circuit breakers with preinsertion resistors in operation is put forward. The validity of the detection method is verified by returning to the factory for disassembly. Electromagnetic field simulation, rapid transient over-voltage simulation and heat capacity test are respectively implemented on the disintegration normal closing resistance, and the improvement measures for the defection of the two types of circuit breakers with preinsertion resistors are put forward, to avoid the occurrence of flashover accidents caused by intermittent discharge of the closing resistance
Bo Niu received the M.S.degree from Harbin Institute of Technology, Harbin, China, in 2015. He is currently a consulting engineering in Power Research Institute of State Grid Ningxia Power Co.
In order to realize fast identification of short-circuit fault current and accurate prediction of zero-crossing point of variable impedance transformer, the short-circuit current identification method based on curvature algorithm of current waveform and the zero-crossing prediction algorithm of short-circuit current based on least square method are studied. The influence of initial phase angle and fundamental frequency angle of different faults on zero prediction under ideal condition, different signal-to-noise ratio and different harmonic conditions is analyzed,and a short-circuit fault model is built with MATLAB and simulated. The results show that the short-circuit current identification method based on curvature algorithm of current waveform and the zero-crossing point prediction algorithm based on least square method can identify fault current quickly, and greatly reduce the prediction error of zero-crossing point time of short-circuit current.
Zhang Qingping (1989 -), male (Han), engineer, master's degree, main research direction: high voltage test and external insulation protection research e-mail: 573630192@qq.com
In view of an abnormal tripping accident of an 800kV SF6 circuit breaker occurred during the operation of S substation, this paper confirmed the fault circuit breaker through the analysis of the secondary protection action, the variation trend of fault recording voltage and current, and the components of SF6 decomposition. The damaged parts in the discharge process and the corresponding discharge trajectories were found by disintegration of returned to the factory. Based on the analysis of the material characteristics of the gas chamber after the fault, the explosion crack analysis of the preinsertion resistors(PIR),and the discharge trajectory analysis of ground fault, the electric field distortion caused by the foreign body inside the tank was confirmed as the cause of the discharge. At last, two kinds of foreign bodies were identified by particle flight path analysis and air gap electric field simulation analysis in the circuit breaker closing process, and corresponding solutions were given.
Bo Niu received the M.S.degree from Harbin Institute of Technology, Harbin, China, in 2015. He is currently a consulting engineering in Power Research Institute of State Grid Ningxia Power Co.
The last circuit breaker (LCB) protection is applied to the hybrid AC/DC power grids for avoiding severe overvoltage problems in the AC/DC equipment caused by the direct tripping of the LCBs, which are the critical circuit breakers in the AC field to keep the connection between DC systems and AC systems. In order to correct and fast identification of the LCBs, a self-adaptive LCBs identification method in the hybrid AC/DC power grids based on the BFS algorithm is proposed. The topology of the AC field is firstly represented as an undirected connected graph. Then, the adjacency matrix for the undirected connected graph is established according to the real-time status of circuit breakers. Finally, the LCBs identification problem is formulated as solving the path’s cut vertices problem by utilizing the BFS algorithm. The simulation results demonstrate the good performance of the proposed scheme for the LCBs identification under various operation modes of the AC field.
Guangxiao Zhang has been working toward the Ph.D. degree in the School of electrical engineering, Southwest Jiaotong University, Chengdu, China, since 2018.
His research interests include the application of wide-area measurements in power systems, power system protection, fault location, and fault isolation.
As the key part of GIS which is widely used in UHV AC power grid, insulation pull rod needs high mechanical performance to ensure the safe operation of GIS circuit breaker. In this paper, the mechanical properties of insulation pull rod for UHV GIS circuit breaker were studied by simulation and static mechanical experiments. Firstly, the stress distribution of the pull rod under bending force was simulated. Then, sensors were arranged on the surface of pull rod according to the simulation results. Finally, bending and tensile experiments were carried out to get the strain changes of pull rod's surface. The experiment results showed that the tensile strength of the pull rod is much greater than the bending strength. And the closer to the fixed end, the greater the strain was in the bending experiment. As for tensile experiment, the strain measured by each sensor were very close. The maximum strain measured were 10391με and 9104με respectively in the bending and tensile experiments, and the corresponding maximum force is 6.77kN and 290kN, but no yield phenomenon was detected. The experimental data can provide guidance for the manufacture of insulation pull rod and enhance the reliability of UHV GIS transmission technology.
His name is Hu Ruizhi. He is a postgraduate from the school of electrical engineering, Xi'an Jiaotong University. His main research direction is the insulation structure design and material performance of power equipment.
In order to study the characteristics of DC circuit breaker with different insulating medium, the structure and working principle of high-speed mechanical switch based on vacuum and SF6 are analyzed, and the basic idea of its design and research is obtained. Starting from the aspects of insulation and temperature rise, the insulation characteristics and temperature rise characteristics of different mediums such as vacuum and SF6 are compared and analyzed. The dynamic insulation experiment loop is designed and built, and the impulse voltage waveform is used to test the insulation fast recovery characteristics of high-speed mechanical switches with different media in milliseconds. Through the comparative study, the applicable scenarios of vacuum and SF6 high-speed mechanical switch are proposed, which provides a reference for the development and application of high-speed mechanical switch.
Sun Keke, male, born in June 1982, Senior engineer, master's degree, top talent of Pingdingshan, vice manager of technology center of Pinggao Group Co., Ltd. of State Grid Corporation of China, mainly engaged in the research and development of HVDC and VSC equipment.
High-power solid-state switches are the key components of hybrid DC circuit breaker. At present, the application of solid state switches in hybrid DC circuit breakers needs to be highly customized. There is no design standard and mature experience to refer to, which limits the development and application of DC circuit breakers. In this paper, a parametric design platform for solid-state switch components in hybrid DC circuit breakers is established. The database is used to store functional characteristics and attributes of components, topologies, and other parameters. The type of solid-state switching devices, component topology, MOV parameters, and buffer branches are designed to meet the requirements of breaking voltage, breaking current, and energy dissipation. Finally, based on the parametric design platform, a 10kV IGCT component was developed and experimental tests were completed, which verified the accuracy and feasibility of the design platform.
Ziyue Cheng was born in Shaanxi Province, China. She graduated from Xidian University in 2019 with a major in electrical engineering and automation. She is currently working toward a master's degree in electrical engineering from Xi'an Jiaotong University. Her research direction is mainly DC current breaking.
The breaking overvoltage of DC circuit breaker (DCCB) will affect the safe operation of DC distribution network. Therefore, the breaking overvoltage characteristics of the DC circuit breaker is analyzed. Firstly, the configuration and protection strategy of DC circuit breaker in the DC distribution network are given. Then, the simulation model of the DC distribution system with DC circuit breaker is established, and the breaking overvoltage level of each converter station is simulated and analyzed when the fault occurs in different positions of the DC distribution network. The results show that the overvoltage level of the DC distribution network can be significantly improved by the breaking operation of DC circuit breaker, and the reasonable configuration of the metal oxide varistors (MOV) is needed to limit the breaking overvoltage.
QU Lu, assistant researcher at Tsinghua University. His research interests include DC distribution network and DC breaking technology.
This article introduces a 10kV/10kA module for DC Circuit Breaker(DCCB) based on 4-inch IGCT(Integrated gate commutated thyristor). The turn-off capability of 4-inch IGCT under reliable snubber conditions is researched at first. Then, the current-balancing experiment of the module is introduced. It is found that two IGCTs in parallel have a special current distribution problem at the moment of turn-off. The main influencing factors of current-balancing is analyzed during the module experiment. That is, the pressure distribution problem of IGCT is the major factor against current-balancing. Combining simulation and pressure experiments, the current-balancing problem of IGCT in parallel is solved by optimizing the module structure. The current-balancing coefficient of module is improved to above 0.93. Finally, the module passed the turn-off test verification of 10kA successfully, promoting the development of IGCT in the field of DCCB.
Zou Ping currently is an IGCT application engineer at CRRC. He earned his Bachelor's degree from Central South University in 2011. He has been engaged in applied research of power semiconductor devices since joining CRRC.
The current injection based mechanical DC circuit breakers (MDCCB) are widely applied for its superiority of low on-state losses and low cost. To realize full range current interruption and high dielectric recovery strength, a novel topology of MDCCB is proposed in this paper. The commutation path consists of two parallel capacitors, small capacitor for small current interruption, and small capacitor parallel with large capacitor for large current interruption. By using bridge type circuit, sufficient dielectric recovery time is provided. Moreover, interrupting characteristics under different combination of small and large capacitors is analysed by simulation. And the principle of optimal capacitors value assignment and the design method of breaking threshold current of using large capacitor are obtained. Finally, a simulation model is built to verify the proposed breaking scheme.
Xiaomin Zhao was born in 1984, Pingdingsan, Henan Province, China. He is currently with State Grid Pinggao Group Co, LCD. His research interests in microgrid and DC distribution equipment.
For substations which used to gather new energies, or for the middle of a long transmission line, and for the receiving end with intensive loads, the network needs high voltage(HV) shunt reactors applied to lower voltage of the bus, which puts forward new demands for the insulation level of the HV shunt reactors, and capacity of nearby main equipment such as capacitive voltage transformer(CVT). In this paper, the mechanism of transient voltage of switching off HV shunt reactor connected to AC bus was explained. The influence factors, which included capacity of HV shunt reactors, current chopping, reignition, substation arrangement methods, were considered during the simulation. Although the transient voltage amplitude during the operation was high, its oscillation frequency reached at the range of lighting overvoltage, and its insulation level should be considered according to the lightning impulse of the equipment. To solve the problem of high amplitude and frequency of CVT current caused by the transient voltage, restraining measures were discussed and analysed. The results of this paper can provide timely and scientific reference and basis for project design and operation.
XU Wenjia, female, engineer, Ph. D. student, her research area includes electromagnetic transient simulation, UHV AC transmission technology.
DC circuit breaker has been a research hotspot in recent years. However, currently, DC circuit breakers are frequently used in the lab to perform breaking tests in the laboratory using a power frequency synthesis loop. The equivalence of the DC circuit breaker is to be discussed. This article aims to provide a test system design scheme that satisfies the technical requirements, that is, at a voltage level of 10kV, the system can provide a 2kA rated current and a 20kA short circuit current with a 6kA/ms rise rate to simulate an actual short circuit condition, and Based on this, a successful breaking of the mechanical DC breaker can be achieved. The key work of this paper is to simulate the establishment of the simulation model of the test circuit, as well as the selection of circuit parameters and the selection of components. This enables the shunt to meet the 20kA short-circuit current and the 2kA rated current. The model of DC circuit breaker was established by PSCAD. It has certain guiding significance and reference significance for the actual establishment of DC circuit breakers and test platforms in the laboratory.
Keywords：DC circuit breaker, Synthetic circuit, PSCAD
I am a sophomore of North China Electric Power University. My name is Changbo. Today, I will show you my thesis
The switching of AC filter in HVDC transmission project can cause serious inrush current and overvoltage, which causes damage to the high-voltage equipment and cause the imbalance protection of the AC filter to frequently false operation. Closing resistors or phase-controlled technology are usually used to restrain the inrush current. In a converter station of Northwest Power Grid, the closing resistor has failed to effectively restrain inrush current many times. For the actual working conditions of this converter station, this paper simulated and analysed the closing inrush current and overvoltage of different closing resistors and the phase-controlled technology. The results show that overvoltage cannot be significantly restrained as closing resistor increases from 400 ohms to 1500 ohms, but the inrush current increases greatly. For BP11/BP13 filters, the inrush current is 4.8 p.u. when closing resistor is 1500 ohms; while it can be limited to 2.9 p.u. by adopting the phase-controlled technology. The research results can provide a basis for HVDC engineering design and equipment selection.
Junbo Deng(correspondent author), 1976 -, male, Ph. D., associate professor, graduated from University of Tokyo in Japan in 2010, is now working at Xi'an Jiao Tong University. His current research is focused on AC/DC power system overvoltage simulation, gas surface discharge measurement, insulation state diagnosis and other aspects.
With features of negligible operating losses and low construction cost, mechanical direct current circuit breakers (DC-CBs) with auto-reclosing function have promising application prospects in DC system with overhead lines to ensure its reliability, flexibility and stability. In order to realize reliable current interruption and auto-reclosing of mechanical DC-CBs with current commutation drive circuit (CCDC), novel operating strategy for mechanical DC-CBs with CCDC during the whole process of dealing with DC faults, including current interruption sub-process and auto-reclosing sub-process, is proposed first. Then, operating characteristic of mechanical DC-CB with CCDC and its equivalent circuit during different stages of the whole process of dealing with faults are analyzed, and impacts of capacitor (C) in DC circuit breaker on transient interruption voltage of ultra-fast mechanical switch, characteristics of residual current, and reclosing current are analyzed. Finally, based on impacts of capacitor, design criterion of capacitor in accordance with DC system parameters are proposed. In the end, case study is carried out in PSCAD/EMTDC to verify the theoretical analysis and the design criterion of capacitor.
Weijie Wen received Ph.D. degree in electrical engineering at Tsinghua University, Beijing, China in 2017. Currently, she is a lecturer in the Key Laboratory of Smart Grid of Ministry of Education, Tianjin University, Tianjin, China. She is presently working in the fields of fast mechanical switch, current limiters, and direct current circuit breaker.
Buffer circuit is one of the important parts to ensure the safe and reliable fault current breaking of the solid-state DC circuit breaker. Therefore, this paper conducts a research on the buffer circuit suitable for solid-state DC circuit breaker. Firstly, a low-loss solid state DC circuit breaker topology is proposed to meet the fault protection requirements of DC distribution network. Then, the circuit model of the breaking process of solid-state DC circuit breaker is established, and the calculation expression of transient current is deduced. Furthermore, the influence of the buffer circuit parameters on the current breaking characteristic of the solid-state DC circuit breaker is analysed. Finally, the feasibility of the design parameters of buffer circuit is verified by experiments, which lays the foundation for the development of solid-state DC circuit breaker.
Xie Wengang (1988-), male, native place: Linyi, master of engineering, mainly responsible for the simulation calculation and design of flexible DC equipment.
During the short-circuit current breaking of the ultra-high voltage SF6 circuit breaker, it needs to withstand a very high transient recovery voltage after the current zero time, which requires the interrupter to have a very strong breaking capacity. In this paper, the arc simulation method is used to simulate the L90 test process of the SF6 circuit breaker design prototype, and the pressure, temperature and Mach number distributions of the interrupter at the current zero time are obtained. The study found that there is a shock wave in front of the static arc contact inside the nozzle, which causes high-temperature gas to be dissipated between the fractures, which may cause the failure of the interruption. According to the simulation results and design experience, an improvement proposal for the arc extinguishing chamber is proposed for this design structure defect, and the simulation calculation is used to verify it. The calculation results show that the improved interrupter scheme has no shock wave at the front end of the static arc contact, and the improved scheme has achieved the expected results, providing support for subsequent type tests.
Hao Zhang, Senior engineer, master's degree. Research interests include high voltage circuit breaker design and arc simulation.
The problem of the phase shift angle adjustment range of Dual Active Bridge(DAB) converter is studied in this paper. The current stress problem in the different phase shift angle adjustment range of the key components in the DAB converter is thoroughly studied to determine the corresponding phase shift angle adjustment range, reduce the current stress of key components, and improve the converter operating efficiency. The concept of “reactive power” is introduced in the research process. The problem of reactive circulating produced by DAB converter is analysed quantitatively. The variation rule of reactive power of DAB converter is determined. By adjusting switching frequency, the reactive circulating can be reduced effectively and the working efficiency of converter can be improved. Finally, the DAB converter experimental platform is built and relevant experiments are carried out, the results of which verify the correctness of the theoretical analysis.
Changli Shi was born in Hebei province in China, on March 1, 1984. He received the M.S. degree in 2011 from Yanshan University, Qinghuangdao, China and is currently pursuing the Ph.D. degree in Power System and Its Automation at the University of Chinese Academy of Sciences, Beijing, China. His research interests include distributed generation and energy storage technologies, and application of power electronics in power system.