最新刊期
卷 47 ， 期 1 ， 2026
- 摘要：The research on switching-off arc by high-voltage capacitor banks remains relatively scarce in public literature，yet the arc transient process is critical to the safety of high voltage capacitor device. To address the aforementioned issues，in this paper the equivalent circuit is constructed on the basis of Maxwell's first equation and electromagnetic field theory，as well as in combination with EMTP simulations， and the arc characteristics are analyzed through three sets of differentiated case studies（different reactance ratios，arc resistances，and switching phase angles）.The results show that when the reactor current is non-zero，the magnetic field energy must be dissipated via the arc or converted into electric field energy （prone to causing overvoltage）. The arc resistance determines the discharge type（the greater characteristic resistance indicates non-oscillatory discharge，otherwise it is oscillatory discharge）. For capacitor banks of the same capacity，the zero-crossing time for 12% reactance ratio is longer than that of 5% reactance ratio. In case of large initial current，the zero time is increased. In case of short arc duration，the effect of the power frequency can be neglected. The research can provide a theoretical basis for arc control in capacitor banks.关键词：Maxwell's first equation;shunt capacitor device;energy of the magnetic field;circuit breaker;EMTP0|0|0更新时间：2026-04-27
- 摘要：In this paper，the issue of abnormally high measured values in the bridge differential protection current meter in the AC filter capacitor bridge differential protection system of high-voltage direct current （HVDC）projects is studied. Both theoretical analysis and field measurements show that stray capacitances between the ammeter measurement wire and capacitor banks，between the wire and ground and between the wire itself，as well as physical asymmetry in the wiring to the ground，cause differential mode interference， resulting in the measured value of unbalanced current being greater than the actual value. An equivalent circuit model for the stray capacitance is set up in this study，a formula for calculating the measurement error is derived ，and the impact magnitude of the stray capacitance on the measurement results is analyzed. To precisely quantify the stray capacitance parameters，a high-fidelity 3D electrostatic field model of the capacitor banks and measurement wire is set up using COMSOL Multiphysics software so to provide critical input for the error analysis. Finally，using a ±800 kV UHVDC project in Hami，Xinjiang as a case study，the correctness of theoretical analysis is verified by the site test. Moreover，the solution to use collected voltage instead of current is proposed so to achieve equivalent measurement of the unbalanced current.关键词：high-voltage direct current (HVDC) transmission;bridge differential protection;stray capacitance;differential-mode interference;COMSOL Multiphysics;equivalent measurement0|0|0更新时间：2026-04-27
- 摘要：In this paper，the hazards of circuit breaker restrike overvoltage to capacitor banks is studied. The correctness of theory and modeling is verified by setting up EMTP simulation model of 35 kV shunt capacitor device. The overvoltage characteristics in case of normal switching，single-phase，two-phase and three-phase restrik as well as with and without surge arresters are compared and analyzed.The results show that in case of no arresters，the maximum voltage across the capacitor bank during normal switching is 1.366 p.u.；the maximum overvolatge of phase to ground during single phase reclosing is 5.18 p.u.；the overvoltage between poles during two-phase and three-phase restrike is 2.34 p.u. and 2.53 p.u. respectively. With arresters，phase-to-ground overvoltages are limited below approximately 3 p.u.，but overvoltage between poles remains uncontrolled. Based on relevant standards，it is proposed that circuit breakers for capacitive switching should meet class C2-M2 requirements. For 10 kV and below，it is recommended to use aged vacuum circuti breaker or contactor. While for 35 kV and above，SF6 circuit breakers or load switches are recommended to minimize the risk of restrike and provide a basis for the selection of equipment and its safe operation.关键词：EMTP;circuit breaker;restrike;overvoltages;capacitor bank0|0|0更新时间：2026-04-27
- 摘要：In this paper the abnormality encountered during the acceptance test of bridge-type differential current protection for a high-voltage filter capacitor bank is studied. The analysis shows that the odd-numbered string arrangement of capacitors on the rack causes asymmetric parasitic capacitance on both sides of fixed potential points，triggering coupling current deviation and leading to excessive unbalanced current. Such two solutions as main capacitance adjustment and parasitic capacitance balancing are proposed，with the latter favored for its shorter construction period and lower cost. An optimized scheme is screened and validated on-site through quantitative analysis of the impact of adjusting fixed potential points at different levels on the unbalanced current. The adjustment of interlayer fixed potential point arrangements can balance parasitic capacitance distribution and ensure the unbalanced current to meet standards. This study innovatively proposes a parasitic capacitance balancing technique which，through theoretical and empirical combination，provides a replicable technical solution for unbalanced protection debugging in HVDC capacitor banks and offers both significant engineering benefits and application value.关键词：capacitor bank;parasitic capacitance;capacitive coupling current;bridge-type differential current protection0|0|0更新时间：2026-04-27
- 摘要：In this paper a fault case involving trip and fire incident of a 35 kV dry-type reactor during operation in an UHV substation is introduced. The cause of the fault is analyzed through the working principle and structure of the dry-type reactor，test data of the same batch of products，disassembly and inspection of the equipment as well as combination with the fault recording data，and the fault location is basically confirmed. The fault is determined to be caused by the cracking of the reactor's encapsulation and the moisture ingress and corrosion of the polyester film，whih leads to the deterioration of the inter-turn insulation over time. Following the insulation degradation，a single inter-turn short-turn short circuit occurs. Under operating condition，this single inter-turn short circuit is rapidly evolved into a multi-turn short circuit fault. Eventually，the reactor ignites and burns at the continuous temperature rise. Based on the fault occurrence mechanism of inter-turn short circuit of dry-type air-core reactors under long-term operation，certain improvement suggestions for the equipment production process and maintenance strategy of the equipement are made.关键词：dry-type air-core reactor;inter-turn insulation short circuit;encapsulation crack;process improvement;maintenance measures0|0|0更新时间：2026-04-27
Reactive Power Compensation and Filter
- 摘要：In this paper，the mirror principle and Lorentz's law are used to analyze that the busbar in the DC-link capacitor simultaneously experiences both the mirror force and the repulsive force when subjected to high current flow. The calculation model of the bus mirror force，which is set up based on the above principle，is basically correct. Although the mirror force is an oscillating attenuation force，in fact，there is no negative force. The segmented multi-node busbar force calculation model set up in this paper takes the busbars between two adjacent convergence points as the uniform force model of fixed beams，successfully solving the force calculation problem of the busbars. The calculation results are basically consistent with the test results，indicating that the force calculation model is basically correct and can be widely applied. The calculation and test results show that increasing the number of convergence points and the cross-sectional moment of inertia of the busbar are decisive for reducing the deformation of the busbar. The spacing of the busbars and their distance to the cover have a decisive influence on the ratio of the mirror force to the repulsive force acting on the busbars.The reaction force at the welding points of the busbars on the busbars can reach tens or even hundreds of kN，and the brazing points of the busbars are difficult to withstand such a large electromagnetic force. The impulse discharge test of capacitors shows that the busbar is subjected to a substantial electrodynamic force，posing significant destructive risks to both the busbar and the busbar laminations. In extreme cases，the laminations can even be torn a part，necessiting high attention to this issue.关键词：DC-link capacitor;electrodynamic force;convergence;hazard;verification0|0|0更新时间：2026-04-27
- 摘要：DC-link capacitors for VSC-HVDC converter valve is of generally multi-terminal structure，and has high current in operation. Currently，capacitance and tanδ measurements for the capacitors are often performed by referring to the measurement connection methods used for traditional high-voltage power capacitors with two terminal structure. The accurate assessment of the capacitance and tangent of the loss angle（tanδ）ofVSC-HVDC-link capacitors directly impacts such aspects as operational performance and safety reliability assessment. In this paper some issues in existing capacitance and tanδmeasurement methods are analyzed and more rational measurement recommendations are proposed.It is thought that in the development the capacitance and tanδ of high power multiple terminal capacitor，the multi strand copper wire mode shall be adopted .The conclusion plays an important role in guiding ccurate measurement of capacitance and tanδof multi-terminal capacitors.关键词：DC-link capacitor;capacitance measurement;tanδ measurement;connection methods;measurement method0|0|0更新时间：2026-04-27
- 摘要：The dry DC-link capacitor bushing，under the effect of long-term DC bias and high-frequency ripple voltages，is prone to electric-field concentration at such areas as inner edge of sheds and the interface of gasket rings，causes partial insulation aging and thus effects long term operation reliability of the equipment. Although the margin of its power frequency withstand voltage is higher，yet the non-uniformity of electric field distribution is still a key issue in localization design. For improving the accuracy of electric field analysis of bushing，a weak form framework combining the weighted residual method for weakening and finite element discretization is adopted，thereby constructing a three-dimensional electrostatic field model suitable for complete geometries and multi-medium structures，and the local mesh refinement is used in the high-gradient regions to enhance calculation accuracy. The model is used for structure optimization analysis after power frequency withstand voltage test verification. Based on the simulation result，a scheme is proposed to deepen the sheds to 8 mm and increase the thickness of the lower part of the gasket ring to 15 mm， which can significantly suppressure partial field intensity and improve electric field uniformity. The study results in this paper have provided effective guidance for structural optimization and insulation performance enhancement of localized dry DC-link capacitor bushing.关键词：DC-link capacitor;Bushing;finite element method;electrostatic field;weighted residual method;finite element discretization0|0|0更新时间：2026-04-27
- 摘要：This paper，starting from the definition of thermal time constant（TTC）and the principle of thermoelectric duality，deduces the calculation formula of heat disspiation resistance and internal transmission heat resistance of DC-link capacitor，thus obtaining the calculation method of TTC of DC-link capacitor. The calculated values of heat dissipation coefficient and TTC are determined through the temperature rise test of DC-link capacitor. According to the thermoelectric duality principle，the test verification method of the TTC is designed，and the method to determine the temperature rise of core by measuring the temperature rise of the capacitor case is proposed. The test value of theTTC of DC-link capacitor is obtained by cooling method，which verifies the correctness of the test and calculation methods， and is of great significance for the majority of engineers to understand the TTC of capacitor.关键词：DC-link capacitors;thermal time constant (TTC);heat resistance;temperature rise test;heat dissipation0|0|0更新时间：2026-04-27
Capacitor
- 摘要：The monitoring of harmonic components in a resistive capacitive DC voltage divider relies on the capacitance section of high and low voltage arms. The breakage of the resistive capacitive connection piece of the low voltage arm can cause an open circuit in the capacitor and lead to abnormal harmonic components in the AC and DC voltage. In this paper，the fault mechanism of abnormal increase in the pole bus resistive capacitive DC voltage divider of ± 800 kV ultra-high voltage DC converter station is analyzed.The correlation between harmonic components and open circuit of low-voltage arm capacitors is verified through disassembly inspection，simulation analysis，material detection analysis and other technical means.Moreover， the specific preventive measures are proposed，which have important reference，reference value and guidance significance for the design，manufacturing，operation monitoring，maintenance，especially the real-time status and monitoring of resistive capacitive connection piece of resistive capacitive DC voltage dividers.关键词：resistive capacitive DC voltage divider;resistance capacitance unit;low voltage arm;resisive capacitive piece;alternating stress0|0|0更新时间：2026-04-27
Instrument Transformer
- 摘要：With the integration of a high proportion of renewable energy and long distance transmission， the power system is evolving toward a complex，topologically intricate AC/DC hybrid grid characterized by frequent power flow interactions. Traditional average network loss allocation methods based on singledirection tracking or improved methods suffer from significant fairness deficiencies when dealing with largescale inter-regional power transmission and the determination of responsibility for key hub nodes. To address this，in this paper a novel network loss allocation method for AC/DC hybrid systems based on virtual node expansion and regional partitioning is proposed. First，a virtual node model of the AC/DC network is constructed，AC lines and DC transmission channels is unified as virtual load nodes to carry complex power losses，thus achieving lossless physical network operation. Then，an improved modularity index based on the active power allocation coefficient is proposed，and mixed integer quadratic programming is used to solve for the optimal grid partitioning scheme that balances electrical coupling and physical connectivity. Finally，a bidirectional complex power flow tracking model is set up，and a boundary equivalent source/load mechanism is introduced to fairly allocate network loss responsibility bidirectionally among generators，loads，and transmission hub nodes. Numerical examples based on IEEE 39 and largescale IEEE118 node AC/DC hybrid systems show that the proposed method achieves strict conservation of network loss allocation in both 39-node and 118-node systems can effectively identify electrically autonomous regions. The results prove that this method can accurately quantify the transmission responsibility of the main power source and the transmission responsibility of inter-regional interconnection nodes，providing a theoretical basis for refined loss reduction and market-based settlement in AC/DC hybrid power grids.关键词：AC/DC hybrid system;zone division;network loss allocation;complex power;bidirectional allocation model2|0|0更新时间：2026-04-27
- 摘要：The sub-module capacitor of the modular multilevel converter（MMC）is a critical equipment of VSC-HVDCtransmission systems，and its safe and stable operation is key to enhancing system reliability. In this paper an online estimation method for the sub-module capacitance of MMC using dual Kalman filtering is proposed，which reduces the number of sensors. First，the arm voltage and current are obtained through the arm voltage sensor and current sensor. Then，the Kalman filtering algorithm and arm current are used again to set up a mathematical model for estimating the capacitance of each sub-module. Finally，a simulation model is set up in PSCAD/EMTDC for verification，and the estimation error of the capacitance is within 0.5%.关键词：modular multilevel converter (MMC);submodule;capacitor;dual Kalman filter;number of sensors2|0|0更新时间：2026-04-27
- 摘要：Direct power supply from renewable energy sources to electrical loads can not only reduce the construction costs of power equipment，but also improve power utilization efficiency.However，in case of disconnection from the main grid and independent operation，such problems as strong fluctuation of system frequency and voltage due to the lack of the support of the main grid are existed，and power supply reliability is thereby affected. To address this issue，tin his paper a unified power quality conditioner （UPQC） topology integrated with an energy storage device and its corresponding control method are studied. First，the issues of system topology and power quality are analyzed.Then，the proposed integrated control method is described. The paralllel part achieves grid-forming control and the maximum power tracking of photovoltaic systems，and the series part is responsible for power quality management. The control method can make self adjustment in accordance with power generation of renewable energy and，at the same time，achieve the management of such power quality isses as voltage fluctuation. Finally，the effectiveness of the proposed control strategy is verified by simulation.关键词：high-penetration renewable energy;grid-forming control;coordinated control;virtual synchronous generator control;power quality management1|0|0更新时间：2026-04-27
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