最新刊期
卷 47 ， 期 3 ， 2026
- 摘要：Regarding the fire-induced burnout fault of a 35 kV shunt capacitor bank at a 500 kV substation due to the damage of its external insulation，an investigation is carried out based on on-site inspections， analysis of record oscillogram，and the disassembly inspection of a typical characteristic capacitor. It is deduced that in the lower right arm region of the phase C capacitor bank，a capacitor unit experiences arc discharge from an insulator（due to moisture absorption）via the aluminum busbar to the metal frame. This discharge gradually developes into the phase B，causing arc burns on the lower right frame of phase B，and ultimately resulting in a phase-to-phase short circuit between phase B and phase C. At this time，the three-phase parameters of the capacitor are inconsistent，and obvious changes can be observed in the recorded current oscillogram. The fault continues to develop，the three phases of the capacitor bank is short-circuited under the action of high temperature and distorted electric field，and then burn out. To address the issues revelaed by this fault，such preventive measures as enhance routine inspection of shunt capacitor banks that have been in service for over ten years，priortize infrared thermography monitoring and set up an management archive for equipment defect elimination are proposed.关键词：shunt capacitor bank;fire;fault oscillogram;disassembly;arc discharge9|0|0更新时间：2026-07-02
- 摘要：High-voltage AC SF6 circuit breaker in ultra-high-voltage DC transmission systems is responsible for reactive power compensation and harmonic filtering. The frequent operations of AC filter circuit breaker，due to high voltage level and large switching capacity，can cause contact erosion and even lead to failures. Based on the actual line configuration of a converter station，in this paper the PSCAD is used to model and analyze possible operating conditions，the influence of closing resistance on switching transients and the current characteristics under different resistance states is investigated，and the diagnosis methods of closing resistor are proposed. The results show that then the closing resistor in the range of 300～400 Ω，it exhibits excellent comprehensive performance across four types of filters and provides superior suppression in the field of overvoltage across the main capacitor，inrush currents and overvoltage on arrester. By applying such criteria as harmonic analysis，the peak timing of inrush current，and the consistency of three-phase closing，as well as the faults in the closing resistor can be accurately identified. Such three electrical life assessment methods as the dynamic resistance method combined with neural networks，SF6 decomposition product analysis，and historical switching data correction are proposed. The error predicted by the dynamic resistance method is controlled within 4%. On this basis，the on-line monitoring system for closign resistor is developed，enabling real-time assessment of circuit breaker's conditionand providing technical support for the grade operation and maintenance strategy of closign resistor in 750 kV filter bank circuti breakers..关键词：AC filter;closing resistor;Inrush current and overvoltage suppression;electrical life assessment of circuit breaker;Online monitoring system10|0|0更新时间：2026-07-02
- 摘要：In recent years，vacuum circuit breakers are still widely used in distribution network and medium voltage system for frequent switching operation. Especially in the reactive power compensation device of shunt capacitor bank，vacuum circuit breakers are widely used in the opening operation of capacitor bank due to their excellent interruption characteristics. However，during switching capacitor bank，the vacuum circuti breakers are prone to delayed restrikes after current zero. This not only accelerates the insulation aging of the capacitor and shortens the equipmet's service life，but also generates high-amplitude restrike overvoltages，which seriously thretens the safe operation of the compensation device and the power system. Re-strike of vcuum circuit breaker is a transient process of microsecond，and the voltage variation has the characteristics of high frequency oscillation，steep rise and steep fall，which is difficult to be accurately captured by ordinary voltage transformer. To address this issue，an electromagnetic transient model incorporating substations and vacuum circuit breakers is set up using PSCAD simulation software so to perform simulation analysis of likely occurred multiple re-strike condition in switching capacitor bank. The simulation results show that in case of two-phase or three-phase re-strike in the circuit breaker，the interpole overvoltage factor in capacitor banks can reach 2-4 times the reference voltage of system. In case of multiple consecutive re-strike，the overvoltage levels will escalate further，posing more severe threats to insulation of equipment and safety of system. The research findings offer theoretical support and practical guidance for type selection，protection coordination，and overvoltage mitigation strategies of vacuum circuit breakers in switching capacitor banks.关键词：vacuum circuit breaker;PSCAD modeling;shunt capacitor bank;Re-strike over voltage;simulation analysis12|0|0更新时间：2026-07-02
- 摘要：With the advancement of intelligent construction in UHV substations，secondary safety protection equipment plays a critical role in ensuring operational safety. However，the UHV strong electromagnetic interference environment and passive safety regulations present a critical conflit between long-term maintenance-free operation and high real-time response to emergencies for the equipment. To address the coupling issue between power consumption and response time in intelligent protection equipment，in this paper a multi-objective optimization strategy is proposed based on an improved non-dominated sorting genetic algorithm（A-NSGA-II）. First，considering the characteristics of the UHV pulse noise channels，a discrete event-driven micro- energy consumption and worst-case timeliness model incorporating a retransmission mechanism is constructed for the intelligent protection equipment. Then，to address the premature stagnation bottleneck of traditional algorithms，an adaptive mutation operator strategy based on population diversity is introduced，and the crowding distance calculation mechanism based on Euclidean distance is reconstructed，thereby enhancing the algorithm's ability to escape from discrete frontiers and improving the uniformity of distribution. Finally，the optimal compromise solution for the equipment is selected using the Euclidean distance decision-making method. The experinmental results show that compared with the standard NSGA-II and traditional multi-objective particle swarm optimization algorithms， the hypervolume indicator of A-NSGA-II is improved by approximately 18.5%. Under the premise that the equipment response delay meets the safety regulation requirements，the average power consumption current of the equipment is 0.118 mA. Even under harsh channel conditions，the theoretical battery life can still be stabilized for more than five years，which provides a highly valuable theoretical basis and quantitative guidance for the reliable deployment of UHV intelligent protection equipment.关键词：UHV Substations;intelligent protection equipment;multi-objective optimization;NSGA-II;Energy Consumption Modeling8|0|0更新时间：2026-07-02
- 摘要：As the penetration rate of distributed generation in distribution networks continues to increase and various automation technologies keep evolving，the active regulation technology of distribution networks has also become increasingly mature. To further increase the carrying capacity of distributed generation，in this paper a method for enhancing the distributed generation carrying capacity in distribution networks based on coordinated active regulation of reactive power compensation devics and inverters is proposed. The Weibull and Beta distributions are adopted to respectively characterize the stochastic nature of wind and photovoltaic（PV）power outputs，and typical source-load scenarios are generated by combining Monte Carlo simulation with K-means clustering. A coordinated control mechanism integrating inverter voltage-reactive power（volt-var）droop control and a nine-zone diagram strategy for reactive power compensation devices is constructed so to achieve the complementary coordination of rapid local response and continuous optimization. Furthermore，a multi-objective chance-constrained programming model is set up to co-optimize the distributed generation carrying capacity and system operating costs. The Non-dominated Sorting Genetic Algorithm II（NSGA-Ⅱ）and an information entropy-based fuzzy comprehensive evaluation method are used to screen the optimal planning scheme. Finally，the modified IEEE 33-bus distribution system is simulated. The results show that the proposed coordinated regulation approach can effectively increase the distributed generation carrying capacity and successfully mitigate capacity loss even under fault conditions. In the planning analysis，the confidence level of the chance constraints can be determined in accordance with the actual grid conditions of the power grid，providing technical support for the collaborative planning of renewable energy and distribution networks.关键词：distribution system;distributed generation;carrying capacity;chance-constrained programming;NSGA-II algorithm4|0|0更新时间：2026-07-02
- 摘要：The distribution network has become more flexible due to the integration of such power electronic devices as intelligent soft switches and DC/DC converters. Flexible interconnection is gradually emerging as a key technological approach for upgrading the distribution network framework and enhancing its flexibility regulation capability. Multi-port flexible interconnection devices can achieve such functions as energy conversion and power regulation，thereby promoting the utilization and consumption of renewable energy. As for the multi-port flexible interconnect device topology proposed in this paper，the hardware-in the-loop testing research in the pre-demonstration stage is performed. First，the topology structure and each port configuration of the multi-port flexible interconnection device are introduced，and the secondary equipment architecture and hierarchical coordinated control system of the control and protection system of the multi-port flexible interconnection device are designed. Then，the control strategy of the flexible interconnection device is designed based on the grid forming control technology and，on this basis，the hardware-in-the-loop testing scheme design，including RTLAB joint debugging architecture，valve based control equipment design，is performed. Finally，the hardware-in-the-loop testing research is carried out for such typical operating conditions as charging，unlocking，step testing，islanding/grid-connection switching as well as fault-ride-through. The test waveforms confirm the reliability and accuracy of the constructed platform，providing a basis and technical support for the factory integration test and on-site commissioning of the demonstration project.关键词：flexible interconnection;renewable energy;islanding/grid-connected;grid forming;hardware-in-the-loop4|0|0更新时间：2026-07-02
- 摘要：Strong coupling between nonlinear hystersis and the closing phase，together with the core fremanence as a key internal cause of transformer magnetizing inrush current，leads to the challenge of insufficient online identification accuracy in engineering. Condiering the shortcomings of traditional method in feature characterization，in this paper the dual features of closing phase angle and inrush current peak are selected，and a remanence identification scheme based on Relevance Vector Machine（RVM）is proposed. Based on Jiles-Atherton dynamic hysteresis theory，a single-phase transformer field-circuit coupled model is set up in COMSOL Multiphysics. Different initial remanence states are generated through DC pulse injection，and steady-state remanence data are obtained by setting a flux probe in the core center. The nonlinear mapping between remanence and dual features is constructed with verified physical consistency. On this basis，a sparse RVM regression model is constructed，realizing adaptive parameter adjustment via Bayesian automatic relevance determination（ARD）to reduce manual tuning dependency. Simulation results show that this method exhibits high accuracy in remanence inversion，achieving a coefficient of determination R2 is up to 0.998，which confirms its excellent effectiveness in capturing complex nonlinear relationships and enabling precise remanence identification.关键词：Transformer core remanence;Inrush current;Closing phase;relevance vector machine1;finite element simulation4|0|0更新时间：2026-07-02
- 摘要：With the development of large capacity and long-distance offshore wind power both at home and abroad，the use of the offshore-onshore integration VSC HVDC transmission scheme offers greater economic advantages.The offshore-onshore integrated coordinated HVDC transmission technology is multi-terminal VSC HVDC system and the coordiantion and control between converter stations is one of its important research directions. Firstly，based on the introduction of the offshore-onshore integrated transmission topology，the operation and control modes of each converter station in the offshore-onshore integrated VSC HVDC transmission project are clarified. Then，the automatic switching strategy for the control mode of of multi-terminal converter stations，the coordinated control strategy for active power among converter stations， the optimization control strategy for the DC energy storage devices are proposed，and the start-up criteria and implementation process are designed. Finally，the correctness of the core control strategy of the offshore wind power VSC HVDC transmission system is fully verified through the setup of a offshore-onshore integrated VSC-HVDC transmission simulation platform.关键词：offshore wind power;Offshore-onshore Integration;MMC-HVDC;Control mode;coordinated control;DC energy consumption8|0|0更新时间：2026-07-02
- 摘要：Aiming at the problems such as voltage limit violation，increased network loss and frequent operation of mechanical voltage regulation equipment that are prone to occur in distribution networks with a high proportion of distributed photovoltaic access，a dual-time-scale voltage regulation strategy based on reinforcement learning is proposed. Firstly，a dual-time-scale voltage regulation optimization model for distribution networks is constructed，with node voltage deviation and system network loss as the optimization objectives，and the operation constraints of mechanical voltage regulation equipment are considered. Secondly，on the slow time scale，the on-load tap changer（OLTC）and parallel capacitors are taken as the control objects，and the deep Q-network（DQN）is used to achieve discrete decision-making of mechanical voltage regulation equipment. Then，on the fast time scale，the inverter group is taken as the control object， and the ASRN-MAD3PG algorithm is used to achieve rapid reactive power regulation. Finally，the effectiveness of the proposed model and solution method is verified through case studies.关键词：distribution network voltage regulation;dual time scales;intelligent control;multi-agent reactive power optimization;OLTC/shunt capacitors3|0|0更新时间：2026-07-02
- 摘要：To address the issue of uneven DC-side voltage in three-phase four-wire distribution systems under unbalanced conditions，this paper proposes a silicon carbide（SiC）-based multi-port flexible control device（V-UPQC）aimed at distribution network management. By leveraging the high-frequency characteristics of SiC，a modular topology with a common DC bus is constructed，reducing filter size and enhancing power density. In terms of control strategy，the outer loop strategy of the series-side AC voltage is improved，and for the unbalance problem in three-phase four-wire systems，a midpoint potential balancing strategy based on a proportional-integral-resonant（PIR）controller is proposed to effectively suppress DC voltage imbalance. Finally，simulations verify the effectiveness of the proposed device in voltage dynamic compensation and unbalance mitigation.关键词：distribution network;silicon carbide（SiC）;multi-port flexible regulation;series-side AC voltage outer loop strategy;midpoint potential balance3|0|0更新时间：2026-07-02
- 摘要：Thermal runaway and its propogation in Lithium-ion batteries have always been a significant concern in the field of battery safety，and this issue becomes even more pronounced in series-connected modules with high energy density. Based on a series-connected 18650 NCM lithium-ion battery module，the thermal runaway of a cell within the battery module is triggered by an externally applied heat source and the propagation behavior of the series-connected battery module under different states of charge（SOC）is studied. The study shows that there is a clear SOC threshold for the thermal runaway behavior in series-connected battery modules. In case of SOC≤50%，the thermal runaway cannot propagate to adjacent cells. In case of SOC≥75%，the thermal runaway can generate instantaneous propogation，with neighboring cells exhibiting almost simultaneously peak temperatures of thermal runaway. It is known from further energy-balance analysis that propagation of thermal runaway at high SOC is that since the high-temperature product injected from the runaway impact adjacent battery，thereby inducing instantaneous thermal runaway. These findings provide experimental evidence and a theoretical basis for the safety design of series-connected modules and，at the same time，suggest that such measures as physical barriers，judicious placement of safety vents/rupture valves，and localized protection can suppress the propagation of thermal runaway.关键词：Lithium-ion batteries;thermal runaway;thermal propagation;series-connected battery module;battery safety design8|0|0更新时间：2026-07-02
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