With the large-scale integration of new energy sources into power grids, the level of disturbances in new power systems has gradually increased. The disturbances in the 9-150 kHz frequency band may exceed the limit values of the electromagnetic compatibility in the IEC 61000-2-2 standard. However, methods for measuring disturbances in this band are still under development. Currently, IEC SC77A/WG9 is developing a quasi-peak (QP) measurement method of disturbances in the 9-150 kHz band for the IEC 61000-4-30 standard. Therefore, this paper proposes a 9-150 kHz QP measurement method (compressed sensing-phase-locked loop, CS-PLL method) that conforms to the framework of the IEC 61000-4-30 standard. The phase-locked loop (PLL) disturbance tracking part of the method enables disturbance tracking with less computation, whereas frequency pre-estimation effectively shortens the PLL method adaptation process and reduces the measurement uncertainty at short window lengths. After simulation and experimental signal verification, the combination of frequency pre-estimation and the PLL method can achieve a measurement uncertainty of less than 5% in a 200 ms QP measurement window. This meets the measurement window length proposal of the IEC 61000-4-30 standard framework and the measurement uncertainty proposal for this frequency band.

Phase switch devices (PSDs) are one of the most effective measures for mitigating three-phase unbalance; therefore, investigating their optimal siting is crucial for cost-effective deployment and full utilization of their mitigation capability. To this end, this paper proposes a chance-constrained PSD planning method that explicitly accounts for photovoltaic (PV) output uncertainty. First, a three-phase power flow model is employed to accurately characterize the three-phase unbalance in the low-voltage distribution network (LVDN), and a PSD planning model is formulated to minimize the investment cost of PSDs and the operation cost of the LVDN while satisfying the three-phase unbalance requirements. Then, by incorporating chance constraints, the proposed approach permits limited violations of the unbalance limit in low-probability extreme scenarios while enforcing compliance under most operating conditions, thereby effectively addressing the uncertainty of PV output and achieving a trade-off between economy and conservatism. Furthermore, to address the computational complexity induced by the nonlinear terms of the chance constraints, an improved integer L-shaped algorithm is developed to efficiently solve the proposed two-stage integer programming model. Case studies on the modified IEEE-13 bus system demonstrate that the proposed method significantly reduces three-phase unbalance, achieves economical PSD deployment, and substantially improves computational efficiency.

Based on IEC 60034-18-42:2017 standards, this paper conducts the SGS qualification test on Double-Fed Machine rotor bars with different structures. The temperature distribution at various stages, as well as the discharge erosion and its evolution in the rotor slot, are recorded to comparatively analyze the influence mechanism of Conductive Armour Tape(CAT) length on the corona protection effect, temperature rise characteristics, and main insulation performance of rotor bars. Experimental results show that under square wave voltage, the temperature rise of the bars is concentrated in the CAT region, exhibiting a strong positive correlation with the CAT length. Elevated temperature rise promotes slot discharge and damages the slot corona shielding layer; high du/dt should be avoided as much as possible in converter design. Under sinusoidal voltage, the temperature rise is concentrated in the overlapping region of CAT and Stress Grading Tape (SGT). The findings provide experimental evidence and technical support for the optimal design, performance evaluation, and engineering application of corona protection structures for rotor bars in Double-Fed machines.

With the growing adoption of electric vehicles (EVs), vehicle-to-grid (V2G) technology has emerged as an effective means to enhance grid flexibility through functions such as frequency regulation and peak shaving. However, the integration of a large number of power electronic devices via V2G has also raised serious concerns about grid stability. This paper first introduces the circuit configuration of a bidirectional V2G energy conversion system and proposes a novel converter equivalent circuit, i.e., Y-type and Z-type equivalence. A unified small-signal model of the V2G system is then established. From this model, the mathematical expressions for the AC bus current and DC bus voltage under various operating conditions are derived, leading to a common denominator factor, termed the generalized stability factor D(S). Unlike conventional methods that rely on Nyquist diagrams, the distribution of poles and zeros of D(S) is intuitively identified by analyzing its magnitude-frequency and phase-frequency characteristics. The existence of zeros in D(S) is used as the stability criterion for the system. Finally, a simulation model of a clustered V2G energy conversion system is developed. Through systematic reduction in the DC-side capacitance in four distinct operational scenarios, our simulations successfully predicted and validated the emergence of characteristic oscillations at 870 Hz, 730 Hz, 843 Hz, and 893 Hz. This demonstrates the efficacy of the proposed stability criterion across various operating conditions.

In modern power grids, mobile energy storage system (MESS) is essential for meeting the growing demand for electric vehicle (EV) charging infrastructure and maintaining reliable power supply during grid failures. For better utilization of MESS, this article proposes a multimode management scheme to maximize the profit of smart mobile power banks (SMPBs), where SMPB is a multifunctional mobile energy storage unit. A temporal-spatial model is proposed to facilitate the routing and scheduling of SMPBs, combining mobile charging, green hydrogen production, and vehicle-to-grid (V2G) functions. The proposed model couples a power network and a transportation network based on the network flow theory, where the shortest paths can be obtained by the Floyd-Warshall algorithm. Furthermore, the spectral-clustering-based mobile charging and mobile V2G scheme are developed for SMPB. Finally, an optimal routing and scheduling of SMPB with integer and linear decisions is proposed considering real-time electricity prices, photovoltaic (PV) fluctuations, road conditions, flexible charging power for EV, and battery degradation, which is designed for swift resolution using commercial solvers. The effectiveness and economy of the proposed scheme are demonstrated through detailed case studies.

Electric vehicles (EVs), with their inherent charging flexibility, hold substantial potential for mitigating three-phase unbalance in distribution networks. However, how to facilitate ac-tive flexibility provision by EVs remains a key challenge. To ad-dress this, this paper proposes a novel incentive mechanism using generalized Nash bargaining (GNB) based cooperative frame-work to enhance coordination of the distribution system operator (DSO) and EV aggregators (EVAs) for phase balancing (PB). Within this framework, the DSO negotiates with EVAs to deter-mine cooperative operation strategies and corresponding eco-nomic incentives for EVAs based on their contributions to PB. To ensure fairness and promote the cooperation willingness of EVAs, the bargaining power is evaluated by considering both individual flexibility contribution and cooperation dependence to coordinate incremental economic utilities of each participant from the coop-eration. Then, the proposed model is decomposed into a social wel-fare maximization subproblem and a payment bargaining sub-problem to ensure tractability. A distributed proximal decompo-sition algorithm (PDA) and an improved alternating direction method of multipliers (ADMM) algorithm are further designed for privacy protection and successful resolution. Finally, numeri-cal results verify the effectiveness of the proposed method in mit-igating unbalance and strengthening cooperation.

There are still a large number of low-voltage distribution transformers that can only rely on the power supply and sale of the transformer area to calculate line loss, and the network topology and line parameters are ambiguous. The meters used for statistics of power supply and sales are all designed and developed based on traditional power theory, and are only suitable for sinusoidal balanced conditions, unable to analyze non-sinusoidal and unbalanced conditions. This paper proposes a method for measuring and evaluating the line loss of power quality in the transformer area. This method decouples line losses based on IEEE 1459 and uses graph theory to solve the power quality line losses power factor of branch. By establishing the solution function of the power factor of line loss in the transformer area, clarifying the constraint conditions, the power quality line loss is solved by using the line loss of supply volume, the power factor of line loss of each branch, and the fuzzy range of line parameters. The simulation of the actual transformer area model shows that this method can calculate the line loss when the line impedance and length are not clear.

The increasing dc bus voltage and reduced rise times experienced in aeronautical environments present significant challenges to the insulation systems of rotating machines. These conditions can generate elevated overvoltages, raising the risk of partial discharge (PD) in the insulation of inverter-fed motors utilized in more electric aircraft (MEA). Therefore, the design of the insulation system is critical in MEA development, as it is essential for ensuring safety and reliability. This study investigates the degradation of PD inception voltage (PDIV) and PD extinction voltage (PDEV) in enameled rectangular wires commonly used in rotating machines. The experiments were conducted under conditions of high temperature and low air pressure. Additionally, we compared the performance of corona-resistant (CR) and non-corona-resistant (NCR) materials, both of which have the same specifications, during endurance tests at low air pressure. The results indicate that PD events are more likely to occur under aeronautical conditions, and the use of CR materials at low air pressure poses significant challenges. Finally, we evaluated the performance of two novel insulation designs for MEAs to assess their applicability and limitations for operational use in aeronautical environments.

In modern power systems, power quality issues are becoming increasingly severe, and the additional line losses they cause are crucial for accurately evaluating theoretical line loss rates. Accurate calculation of theoretical line loss is the first step in line loss analysis. However, due to the complex topology of low-voltage distribution networks, traditional physical model-based methods are often unsuitable. To address this, artificial intelligence-based big data methods are used to model the complex nonlinear relationships between various influencing factors and theoretical line loss, enabling fast and high-precision calculations. In this study, all relevant factors, including power quality indicators, are considered. Grey relational analysis is applied to evaluate the significance of each factor, and cross-validation is used during feature selection to identify the input dimension with the lowest mean squared error (MSE). Based on the selected data, theoretical line loss is calculated using three algorithms: a particle swarm optimization (PSO)-based random forest, a backpropagation (BP) neural network, and a support vector regression (SVR) model. The PSO-based random forest is ultimately selected as the final model due to its superior performance. Simulation results from real-world low-voltage samples confirm the effectiveness and practicality of the proposed method.

This study investigates the feasibility of utilizing the line loss power factor to assess the reactive, unbalanced, and harmonic line losses in low-voltage distribution networks and explores the method of calculating decoupled line loss values based on this factor. To achieve this objective, we establish preliminary definitions of single-phase and three-phase reactive, unbalanced, and harmonic line loss power factors, drawing upon the principles of electrical theory outlined in IEEE Standard 1459. These power factors serve as crucial indicators for evaluating the severity of line losses caused by reactive power, unbalance, and harmonic problems. Subsequently, the values of line loss attributed to reactive, unbalanced, and harmonic components are decoupled and quantified using the line loss power factor as a fundamental parameter. The effectiveness and accuracy of the proposed method were verified in Matlab simulation and physical experiments.

The linear-motor type magnetic flux pump serves as a wireless power source intended for charging second-generation (2G) high-temperature superconducting (HTS) double-pancake coils (DPC). This study is grounded in the utilization of magnetic flux pump apparatus, in conjunction with the theoretical framework of macroscopic magnetic coupling effects (MMCE). The real-time manipulation of the direct bias magnetic field and the alternating traveling wave magnetic field of the flux pump is employed to facilitate the precise and stable operation of the HTS DPC with a persistent current mode (PCM). Experimental findings demonstrate that the regulation of both the DC bias magnetic field and the alternating traveling wave magnetic field effectively governs the pumped current in the HTS DPC. Notably, exerting control on the alternating power supply, specifically the alternating traveling wave magnetic field, enables the attainment of even greater precision in current regulation and lower system energy consumption, with the load current accuracy presently achievable up to 1%. Additionally, controlling the AC power supply is expected to save between 30% to 70% of energy compared to controlling the DC power supply. This study provides an alternative solution for the PCM operation of the linear-motor type magnetic flux pump, laying a foundation for achieving higher precision PCM and applications in MRI magnets in the future.

As intermittent renewable energy sources (RESs) increasingly become integral to the power grid, the imperative to ensure frequency stability of power grid has emerged as a critical challenge. Addressing this, this paper proposes a novel energy management framework in retired battery-integrated microgrid with grid frequency regulation (FR) and peak shaving. The EV battery can be hierarchically utilized by the two-stage control framework to improve economic efficiency. In the first stage energy management, a novel heuristic algorithm called the walrus optimization algorithm (WaOA) is employed to implement the optimal energy scheduling of microgrid for minimizing operating costs. In the second stage control strategy, a deep deterministic policy gradient (DDPG) agent is applied to dynamically adjust the power sharing of energy storage station according to the states of retired batteries. Furthermore, a comprehensive retired battery aging model is incorporated into the proposed strategy to reduce total battery capacity loss. The simulation results verify the superior performance of the proposed energy management framework under various microgrid scenarios. This work provides a practical approach to the cascaded utilization of EV batteries, which further improves the sustainability and economics of EV batteries.

The clock-inaccuracy at the load measuring point on the 10 kV line leads to an abnormal line loss rate,while the existing manual methods have the problems of low efficiency and low intelligence. Therefore,based on the fluctuation characteristics of line loss rate curve,a new method for identifying the load types of clock-inaccuracy metering points is proposed to fit the mapping relationship between load type and the clock-inaccuracy line loss rate by Bayesian network（BN）. In order to solve the problem of lack of clock-inaccuracy samples,the metering clock deviation modules are respectively set for the load metering points to generate a sample set of clock-inaccuracy line loss rate in the simulation model based on the actual operation data of the line. The fuzzy C-means clustering is then introduced to classify the load according to the shape similarity of the load curve,and the data dimensionality reduction is realized in scenarios with heavy load. Relying on research data from the synchronous line loss management system,the calculation example verifies the feasibility and accuracy of the proposed method. It is shown that the method can realize load type identification of clock-inaccuracy,and provide a reference for quickly locating the abnormal energy meters.

重点分析了系统负载变化时,不连续电感电流模式Cuk功率因数校正PFC(power factor correction)变换器稳定性的变化情况.在变换器工作特性的基础上,根据谐波平衡法和Floquet理论分析,研究结果表明:当负载电阻变小时,即系统由轻载到重载变化时,系统发生了工频频率上的倍周期分岔.给出了系统发生倍周期分岔时的电阻,以及在输出电感、输入电压产生改变时和负载电阻共同构成的系统不稳定与稳定的边界区域图,基于输入电感电流-输出电压的相轨图和输出电压的谐波分析谱,更好地观察到系统的动力学行为.最后通过实验验证了理论分析的正确性.

以不连续电容电压模式Cuk功率因数校正变换器为例,描述了当系统负载增大时存在的慢尺度分岔现象.分析了慢尺度分岔现象的特点和产生原因,根据功率平衡原理推导了系统的谐波平衡解,并进行仿真验证文中理论.结果表明,随着负载电阻的增大,系统会进入倍周期分岔继而进入混沌状态,电路在轻载状态下容易发生分岔现象.这类慢尺度分岔现象及相关分析得到了实验验证.

电网工频时变将导致固定采样率下的非同步采样现象,降低谐波检测精度.A类谐波测量仪器通过硬件锁相克服了该问题,但高昂的价格使其难以广泛应用于实际工程.在嵌入式系统中通过合理的算法校正非同步采样结果,实现谐波的准确测量,能够有效降低设备成本.首先分析频谱泄漏抑制条件与多点变换谐波测量算法特性,研究不同变换点数对频谱的影响,推导在不同采样条件下的最佳变换点数选择式.其次提出优先计算基波及低次奇次谐波频率的平均参考工频优化算法,进一步改善了整体计算效果.最后在STM32嵌入式系统上实现了算法.模拟数据计算及LED灯谐波检测实验结果均验证了在非同步采样下,基于该算法的嵌入式系统谐波测量的高精度性与高可靠性.

Bipolarity in dc microgrids is desirable as it enhances the system's reliability and efficiency. However, the stability assessment for a bipolar dc microgrid is challenging due to the integration of a three-wire dc distribution line and numerous connected power converters, which is different from the stability analysis of a conventional unipolar dc microgrid. In this article, the basic form is arranged by a generalized voltage source or current source, and the simplified form is derived by looking into the different bus ports of a bipolar system in detail. Then, an impedance sum criteria-based stability conditions of different bus ports in the bipolar dc microgrid are proposed. To explore the mutual influence of the stability among different bus ports and investigate the stability issues caused by unbalanced loads connected to the symmetrical bus port, three cases are studied: 1) ±Vdc bus ports are connected with balanced and unbalanced loads; 2) −Vdc bus port introduces the photovoltaic unit and the energy storage unit; and 3) the 2Vdc bus port introduces the photovoltaic unit and the energy storage unit. Finally, a ±24 V bipolar dc microgrid platform is set up to conduct experiments, verifying the accuracy and effectiveness of the stability evaluation method.

In low-voltage distribution systems, the increased penetration of power electronic devices leads to the decentralization of harmonic sources, which puts the sensitive loads or communication systems in the risk status. The conventional methods of point-to-point harmonic control are not applicable. In order to solve this problem without increasing additional investments, this paper focuses on mitigating the harmonic interference through the power factor correction (PFC) converter. Hence, a critical conduction mode (CRM) single-phase boost PFC converter with adaptive harmonic compensation (AHC) control is proposed to reduce the harmonic interference at user side. Firstly, the feed-forward control loop of a PFC converter is decoupled into the fundamental branch and harmonic branch to trace the harmonic interference and generate the compensation current. Then the compensation gain is designed by the compensation loop gain and compensation capacity of PFC converter. Meanwhile, the characteristics of the PFC converter are analyzed to study the effect of the AHC control on the active power transmission and output load, which can provide important support for the proposed method in application. Finally, a 160-W experimental prototype is built to verify the effectiveness of the proposed AHC control.

The computational time of compressed sensing algorithms applied to supraharmonic needs to be improved in online applications. In this paper, a simplified supraharmonic compressive sensing model is proposed. The model first detects the supraharmonic raw spectral array to obtain the estimated sparsity and the index of supraharmonic emissions, which simplifies the sensing matrix in the iteration according to the index and then shortens the whole iteration time of compressed sensing. The simulation verifies that the model can reduce the computation time to less than half of the original compressed sensing model and does not affect the computation accuracy. Finally, the online application effect of the algorithm is verified by experiments.

面对非电类专业"电子技术"实验教学中学生自主性低、创新能力不足的困境,结合专业方向对课程知识能力培养的要求,基于问题导向式(problem-based learning,PBL)教学法对非电类专业实验教学体系进行改革,形成以解决实际问题为目标的系统化实验教学方式.在有限的学时内,尽可能地提升非电类专业学生电子技术实验的综合技能,即电路分析、电路设计和电路调试等能力,增强实验内容的趣味性和挑战性,激发学生实验的积极性和创新能力.教学实践表明,PBL教学模式在非电类专业电子技术实验教学中取得了良好的教学效果.