LOW VOLTAGE APPARATUS

Optimization Design for Quality Consistency of Balanced Armature Relay Contact System Based on Digital Model

CHEN Dongxu, LI Jianping, XU Le

2025, 0(7): 1-8. doi:10.16628/j.cnki.2095-8188.2025.07.001

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The main failure mode of balanced armature relays during operation is contact ablation in the contact system, which is caused by large dispersion in the pull-in speed during the relay’s pull-in process. Excessively high pull-in speed can lead to contact bounce, while excessively low pull-in speed can result in poor pull-in. Taking a certain type of product as the research object, a method for consistent parameter design and tolerance design based on digital models is proposed. By establishing an electromagnetic-mechanical co-simulation model of the entire machine, the influence laws of key parameters such as contact gap and initial pressure on the pull-in speed are analyzed. After optimization, the average pull-in speed is reduced to 0.3224 m/s, and the standard deviation is decreased by 17.9%. Through tolerance design, the standard deviation is further reduced by 34.3%. The tests show that the proposed method can effectively suppress contact bounce and arcing phenomena, and improve the product quality consistency.

Identification Method of Failure Mechanism Consistency for Electromagnetic Relay Based on Crystal Vibration Energy

XING Huafeng, FU Rao, LI Huiyan

2025, 0(7): 9-17. doi:10.16628/j.cnki.2095-8188.2025.07.002

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Accelerated degradation test is often used in the reliability evaluation of switching electrical appliance.The consistency of failure mechanism under each accelerated stress is the basis for accurate and efficient evaluation of its reliability. Firstly, in view of the possible misjudgment of the failure mechanism consistency based on failure physics and the fact that the quantitative analysis method based on Arrhenius model can not describe the degradation law of progressive stress test data, a degradation model based on crystal vibration energy is proposed.The t-distribution hypothesis test and Monte Carlo simulation are both carried out to verify that the model can be used to describe the degradation law of progressive stress test data.Then, a method based on the degradation model for identifying the consistency of failure mechanism is proposed.Finally,the continuous load accelerated degradation test example of a relay shows that it is mutually verified with destructive physical analysis.The proposed method, on the basis of describing the degradation law of the progressive stress data, can be used for the quantitative analysis of the failure mechanism consistency under temperature accelerated stress and has certain effectiveness.

Research on Secondary Cable Wiring Across Switchgear Door Based on Arc-Shaped Buffer Transition

JIN Tianran, CAI Ning, XUE Huan, DAI Dongyun, WANG Fumin

2025, 0(7): 18-24. doi:10.16628/j.cnki.2095-8188.2025.07.003

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The mechanical fatigue issue of door-crossing secondary cables during the opening and closing of instrument compartment doors is addressed by proposing an optimized wiring scheme based on an arc-shaped buffer transition.By increasing the reserved length of door-crossing cables and implementing pre-bending treatment, a arc-shaped flexible structure is constructed, achieving a 20% reduction in tensile strain and a 34% decrease in stress concentration values during cable movement.Cable harness flexibility is effectively enhanced and insulation layer lifespan is extended.Simulation experiments and prototype verification results demonstrate that the proposed solution significantly improves the uniformity of strain distribution in cable harnesses, providing both theoretical foundations and practical guidance for ensuring the reliable operation of intelligent switchgear.

Research on Circulating Current Suppression for Parallel Operation of Inverters with Droop Control

ZHAN Xiangxin, SUN Zhonghua, ZHAO Ye

2025, 0(7): 25-29. doi:10.16628/j.cnki.2095-8188.2025.07.004

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In order to suppress the circulating current generated during the parallel operation of inverters with droop control.By analyzing the basic principle of traditional droop control and the defects of droop control technology with the introduction of virtual impedance,a control strategy adding an integral term into the reactive power adjustment link is proposed.Simulation results verify that the proposed strategy achieves reactive power the equal sharing among parallel inverters and has an obvious inbitory effect on the circulating currents in both transient and steady-state.

Design of Current Transformer for Intelligent Molded Case Circuit Breaker

LI Xinyu, YIN Jianqiang, SHAO Jianguo, BAO Guanghai

2025, 0(7): 30-38. doi:10.16628/j.cnki.2095-8188.2025.07.005

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In an intelligent molded case circuit breaker (MCCB),the current transformer (CT) not only collects current signals but also supplies power to the electronic trip unit.If the design is inadequate, insufficient power can be provided at low current levels or when the load impedance is high,leading to core saturation,secondary-side current distortion,thereby causing measurement errors.To address these issues,a 63 A rated intelligent MCCB is selected as the research subject.The range of CT turns meeting the requirment of measurement and energy extractions is theoretically derived.Then, Ansys simulations are conducted to determine the optimal number of turns.Additionally, a MOSFET is introduced on the CT’s secondary side to control the load-side voltage by means of PWM.Simulation and experimental results show that the designed CT can maintain undistorted output waveforms with an equivalent load impedance of 1 kΩ in a current range of 0.4I_n to 10I_n.Across the entire current range, the solution ensures accurate measurement while meeting power supply requirements.

Electric Field Optimization Design of 40.5 kV SF₆ Interrupter

ZHI Jiaojiao, SHI Jinqiang, PANG Bo

2025, 0(7): 39-43. doi:10.16628/j.cnki.2095-8188.2025.07.006

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An optimization design is carried out to address the insulation problem of SF₆ interrupter for a 40.5 kV gas-insulated ring main unit. The finite element software is used to simulate the electric field of the moving and static contact structure in the 40.5 kV SF₆ arc-extinguishing chamber. The simulation results show that the electric field intensity is concentrated at the arc of the end of the moving contact and the arc of the outer end of the static arc contact, and the electric field distribution between the moving and static contacts is extremely unbalanced.Electric field simulations of the arc-extinguishing chamber are conducted with and without a voltage-equalizing structure at different opening distances, and with the voltage-equalizing structure at different positions. The influence of these conditions on the electric field distribution of the arc-extinguishing chamber is analyzed, and the structural optimization of the arc-extinguishing chamber is completed. After optimization,the maximum electric field intensity at the sampling boundary of the moving contact end decreases by up to 30.45%. The rationality of the structural optimization is verified through insulation tests.The test results show that adding a voltage-equalizing structure and arranging it at an appropriate position can meet the interrupter insulation requirements of the 40.5 kV voltage level without increasing the opening distance.

Contact Failure Analysis and Optimization Design of Molded Case Circuit Breaker

LIU Haibin, XIANG Xiaoqing, ZHOU Mingming

2025, 0(7): 44-48. doi:10.16628/j.cnki.2095-8188.2025.07.007

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A short-circuit overload test under an effective current of 8 000 A is conducted on a certain double-break moulded case circuit breaker (MCCB),and the contact ablation fault that occurred is analyzed. First, a theoretical calculation of the electric force is performed. Then, using Maxwell 3D finite element analysis software combined with the Holm force calculation formula,the electric repulsion of the double-break MCCB is calculated. The trends of the two calculation results are consistent, and the cause of contact ablation is determined through comparison.The error between the simulation calculation result and the measured value of contact pressure does not exceed 8%,and the used calculation method can provide a reference for the design and optimization of the MCCB contact system.

Design of a Contactless AC Contactor Based on STM32

LIU Wei, ZHANG Yuqing, YU Qingrui, WANG Jun, HUANG Wenhui

2025, 0(7): 49-58. doi:10.16628/j.cnki.2095-8188.2025.07.008

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To address the limitations of traditional mechanical contactors in intelligent control systems, an intelligent contactless contactor based on the STM32 microprocessor has been designed and implemented.The STM32 is utilized as the core controller. Its I/O port resources and powerful embedded processing capabilities are utilized to construct a human-machine interaction interface and realize real-time acquisition and processing of contactor control signals.Meanwhile, a passive filter circuit is designed to effectively suppress electromagnetic interference, ensuring the system’s stable operation in complex electromagnetic environments.Electromagnetic compatibility (EMC) tests and impulse voltage withstand tests are conducted on core components.The test results show that it exhibits excellent control accuracy and stability under various operating conditions, which can meet the design requirements.

Research on Economic Feasibility of Multi-Energy Complementary Systems in Medium- and Long-Term Markets

CHEN Yeshuai, BIAN Guoliang

2025, 0(7): 59-70. doi:10.16628/j.cnki.2095-8188.2025.07.009

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Driven by the “Dual Carbon” goals,the large-scale development of renewable energy faces integration challenges due to its inherent intermittency and volatility.To enhance system flexibility and promote renewable energy accommodation, the economic and stability advantages of multi-energy complementary systems in electricity markets are investigated, guided by China’s national policy on “Integrated Source-Grid-Load-Storage and Multi-Energy Complementarity.” By incorporating electricity market rules and multi-energy complementarity characteristics, a medium- and long-term market-clearing model is established. Using nonlinear programming theory and a particle swarm optimization algorithm, simulations are conducted to solve the bidding strategies of power generation and large consumers’ electricity purchase decisions.Through market-clearing result analysis and policy adaptability research, the superiority of multi-energy complementary systems is validated in terms of economic benefits, market resilience, and cost structure, which can provide theoretical support for market-based renewable energy integration.

Research on Cross Market Collaborative Operation Technology of Electricity-Carbon-Green Certificates in New Power System Based on Blockchain

BAO Lei, CHANG Liangliang, WEI Pengjie

2025, 0(7): 71-80. doi:10.16628/j.cnki.2095-8188.2025.07.010

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The electricity-carbon-green certificate markets in the new power system faces the problems,such as inconsistent transaction targets,inconsistent transaction accounting,and non sharing of transaction information.The application of blockchain technology can effectively solve the above problems.Based on blockchain technology,the collaborative operation technology of the electricity-carbon-green certificate markets is studied. Firstly, a deep analysis is conducted on the collaborative relationship among the “electricity-certificate-carbon” markets.Secondly,a unified integral certification mechanism is established by using blockchain to connect the transaction subjects among the electricity-carbon-green certificate markets, and a traceability model for electricit-carbon-green certificate is built by combining blockchain smart contracts and consensus mechanisms to ensure the transparency of transactions and data consistency among all participants. Finally, experiments are carried out to verify the traceability of electricity-carbon-green certificate as well as the consensus performance of the blockchain, and the results show the effectiveness of the market system.

Design and Research on Propulsion System Simulator Based on Combination of Real Installation and Simulation

FU Guangjing

2025, 0(7): 81-83. doi:10.16628/j.cnki.2095-8188.2025.07.011

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Aiming at the problems of high cost and poor versatility of shipboard simulator, and insufficient authenticity of pure virtual simulation equipment training,a design scheme for a ship propulsion system simulator based on the integration of physical equipment and simulation is proposed.The design principles,system architecture,hardware design,and software design of the simulator are described in detail.With the aim that the limitations of real-ship training are broken through via a real-virtual interactive environment, the drawback that pure simulation training lacks physical feedback is overcome, and the training effectiveness for trainees is enhanced.

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