Search Results (458)

The accumulation of ice on power lines severely affects the safety of power systems. Conventional ice melting methods suffer from poor flexibility and adaptability, accompanied by high power consumption. As a novel technical approach, distributed ice melting deploys modular and movable ice melting units at key sections of overhead ground wires, which generate heat on site according to the actual icing conditions of icing segments, and imposes high requirements on the miniaturization of ice melting equipment as well as the regulation strategy of ice melting current. This study proposes a distributed ice melting method for overhead ground wires based on AC power supply, which can adjust the current in accordance with the specific demands of wire protection and ice melting for different line sections. The feasibility and effectiveness of the proposed method are verified through thermodynamic simulations and experimental tests. The de-icing method injects power–frequency AC into the overhead ground wire through a Scott transformer combined with a series capacitor reactive power compensation structure, enabling on-demand regulation by adjusting capacitor switching strategies and transformer operating modes. This approach balances efficiency and flexibility. Based on a reactive power compensation capacity current control strategy and thermodynamic analysis, an electro-thermal-fluid field coupling simulation model for the experimental ground wire was developed. The current regulation strategies for different environmental and operating conditions were calculated and validated. The simulation results show that, under different conditions, the adjustable current effective values of the de-icing system in this model range from 101 to 380 A (line maintenance current), 304 to 622 A (critical de-icing current), and 661 to 1121 A (maximum de-icing current). Field tests demonstrate that this method can stably achieve AC de-icing and current control. For the experimental JLB40-150 model ground wire, adjusting the injected current to 350 A enables safe operation under line maintenance conditions, with a limit not exceeding 400 A. This paper provides a more efficient, flexible, controllable, and widely applicable method for the de-icing of overhead ground wires. Full article

Phase-angle AC control is a low-cost technique for regulating power in resistive loads, but its performance depends on accurate trigger timing. This study quantitatively compares an ESP32-based phase-angle controller implemented in MicroPython and in native C using ESP-IDF. Firing delay was measured over 1000 consecutive cycles at firing angles from 10° to 150° under a 60 Hz supply, and the timing error was converted into equivalent angular deviation. The native C implementation reduced the mean timing error from 218.2–234.7 μs in MicroPython to −10.3–6.1 μs after calibration, corresponding to an average improvement of approximately 225 μs or 4.86° across the tested angles. In the current dataset, the measured standard deviation remained angle-dependent and numerically similar in both environments, ranging from 2.5 to 10.1 μs. Oscilloscope measurements confirmed the expected phase-angle operation and the practical timing displacement between firmware strategies. The results show that the principal advantage of the native implementation is improved absolute synchronization accuracy, whereas the residual short-term jitter remains dominated by the shared detection and triggering chain. Full article

In future active distribution networks with high penetrations of renewable energy, flexible loads are expected to play an increasingly important role as reserve resources to support the sustainable and reliable operation of power grids. Accurate evaluation of flexible load reserve capacity is therefore essential for reliable reserve scheduling. Existing research mainly focuses on the operational characteristics and physical constraints of flexible loads, while insufficiently accounting for user response willingness and the uncertainty of user decision-making behavior, which may lead to biased reserve capacity assessments and impair the sustainability of reserve supply in actual grid operation. To address this issue, this paper proposes a results-oriented reserve capacity evaluation method for flexible loads that explicitly incorporates user response willingness. Specifically, a fuzzy logic system is developed to quantitatively characterize the response willingness of electric vehicle (EV) and air-conditioning (AC) users under multiple influencing factors. Then, a probabilistic modeling approach for user decision-making behavior is established using the theory of planned behavior, enabling explicit representation of behavioral uncertainty. Furthermore, a comprehensive reserve capacity evaluation framework for flexible loads is constructed by integrating user willingness states, sustainable response duration, and operational power constraints. Finally, the case studies demonstrate that the proposed method can effectively improve the objectivity of flexible load reserve capacity assessments while maintaining high user participation willingness, thus supporting the long-term sustainable application of flexible loads as grid reserve resources. Full article

The eddy current braking system (ECBS) is a crucial non-contact technology for high-speed railway. Conventional DC-excited systems face significant challenges such as excessive rail heating and high-capacity power supply requirements. This paper proposes a novel ECBS with AC excitation and auxiliary capacitor to achieve integrated energy recovery and power supply optimization. To evaluate its performance, a rigorous analytical framework is developed. First, a 2D subdomain model is established by incorporating the longitudinal end effect to solve the magnetic field distribution. Subsequently, an equivalent circuit is derived from the subdomain results to investigate steady-state braking characteristics and power flow. Analysis results demonstrate that the proposed system not only generates controllable braking force but also converts a portion of kinetic energy into storable electrical energy, effectively mitigating secondary rail heating. Most significantly, the implementation of an optimal auxiliary capacitor (134 μF) is found to reduce the required inverter capacity compared to inverter-only conditions. These findings provide a theoretical foundation and a practical design tool for developing high-performance, energy-efficient braking systems in high-speed transportation. Full article

Layered double hydroxides (LDH) demonstrate significant potential in flexible superca-pacitors due to their high energy storage capability and adjustable architectures. Never-theless, the practical specific capacitance exhibited by current LDH remains below expec-tations, which is attributed to suboptimal electrode performance and limited active sites. Herein, a novel Fe-doped NiFeCo-LDH/NiFeCoO nanosheet composite supported on car-bon cloth was designed and fabricated as a flexible electrode. In this composite, the Ni-FeCo-LDH supplies numerous reactive centers and accelerates electrochemical kinetics, while the NiFeCoO and carbon cloth significantly improve electrical conductivity and cy-cling stability. Moreover, the heterointerface formed between the LDH and the metal oxide phase further facilitates charge transfer. Owing to such synergistic interactions, the pre-pared NiFeCo-LDH/NiFeCoO@CC electrode demonstrates an excellent areal specific ca-pacitance of 3.282 F cm⁻² at a current density of 1 mA cm⁻², while maintaining a high ca-pacity preservation reaching 88.09% following 5000 cycles. Furthermore, the assembled NiFeCo-LDH/NiFeCoO@CC//AC asymmetric supercapacitor delivers an outstanding en-ergy density reaching 0.302 mWh cm⁻² under a power density of 0.776 mW cm⁻², coupled with an excellent capacitance preservation of 85.29% over 5000 cycles. Meanwhile, it can maintain its initial capacitance under varying bending degrees, rendering it widely ap-plicable for future advanced flexible and wearable electronic devices. Full article

Synchronous Alternating Current (AC) power systems are increasingly supported by embedded High-Voltage Direct Current (HVDC) links to enhance operational flexibility and ensure security of supply. However, the loss of High-Voltage Alternating Current (HVAC) interconnections in these synchronous areas may lead to transmission network splitting, posing serious challenges to frequency stability due to the reduction in overall system inertia and stiffness. In this paper, a supplementary control layer is proposed to enable embedded HVDC systems, particularly those based on modern Voltage Source Converters (VSCs), to support frequency stability under post-splitting conditions. The proposed control strategy combines Angle-Difference Control (ADC), Frequency-Difference Control (FDC), and feedforward action, enabling fast and coordinated active-power modulation. A single-bus, dynamic multi-area Load Frequency Control (LFC) model is developed, combining the regulation of thermal units, Renewable Energy Sources’ (RESs’) Fast Frequency Response (FFR) with Synthetic Inertia (SI), and VSC-HVDC modulation. The effectiveness of the proposed control layer is demonstrated by applying it to the East Tyrrhenian Link (ETL), an embedded VSC-HVDC interconnection connecting Sicily with the mainland of Italy, under a post-splitting low-inertia condition in which Sicily operates as an islanded synchronous system, i.e., after losing synchronism with the mainland of Italy, in a 2030 scenario condition. The simulation results demonstrate that the proposed controller enables embedded VSC-HVDC systems to actively participate in post-splitting frequency containment and damping, as well as coordinated active power reallocation, thereby enhancing overall system stability and resilience. Full article

The paper presents SFPD, the new open algorithm developed by the University of Padova (PD in the acronym) for computing the steady-state regime due to any number of simultaneous faults (SF at the beginning of the acronym) both short circuits and open conductors. The algorithm does not have simplified hypotheses, since it benefits from the pre-fault regime based on PFPD_MCA (power flow by University of Padova with multiconductor cell analysis), a multiconductor power flow (developed and published by the first author) which takes into account both the active conductors (i.e., the phases subjected to the impressed voltages) and the passive conductors (i.e., the interfered metallic conductors, namely earth wires of overhead lines, metallic screens and armors of land and submarine cables, enclosures of gas insulated lines, return and earth wires of 2 × 25 kV AC high-speed railway supply system, etc.). Different types of faults are considered, and where they occur (also along the lines), by means of a suitable admittance matrix in phase frame of reference and embedded inside the overall network bus admittance matrix. Some comparisons with simplified approaches are presented in order to demonstrate the power of the method. Eventually, application to the real Italian network is comprehensively shown. Full article

This research paper presents Volvo SmartCell, an AC battery technology that integrates modular multilevel converters and battery cells to form a unified system for electric vehicle propulsion and power supply. The research work addresses the broader challenge of reducing driveline cost and complexity by replacing traditional components such as inverters, onboard chargers, centralized DC/DC converters, vehicle control units and many more. SmartCell uses distributed Cluster Boards comprised of H-bridges which are controlled via wireless communication to generate AC voltage, deliver redundant low voltage power, and support cell level protection mechanisms. The prototype testing demonstrates that the system can supply traction power by engaging clusters according to the required voltage depending on motor speed, achieve AC grid charging by synthesizing sinusoidal voltages without a dedicated charger, and provide autonomous DC/DC operation through cluster level voltage regulation. Simulations further indicate that multilevel voltage generation can reduce switching losses and improve electric machine efficiency compared to conventional systems. Additional benefits include active cell balancing, support for mixed cell chemistries, and high redundancy through multiple independent power branches. Challenges remain in wireless bandwidth limitations and cost optimization of Cluster Boards. Ongoing development aims to enhance communication robustness and validate safety for non-isolated grid charging. Full article

The growing electrification of ports and maritime transport requires flexible power systems capable of supplying multiple voltage levels with high efficiency and power quality. Battery-based power barges offer a promising solution, but their power conversion systems must handle wide voltage and power ranges while remaining stable under dynamic operating conditions. This paper presents a scalable multi-stage power conversion architecture for battery-based power barges that can supply both low-voltage and high-voltage AC loads from a common DC source. The system combines isolated Dual Active Bridge (DAB) DC–DC converters with a three-level Neutral-Point-Clamped (NPC) inverter. An input-parallel output-series DAB configuration is used for high-voltage operation, enabling modularity and scalability within semiconductor limits. A coordinated control strategy ensures stable DC-link regulation, balanced module operation, and high-quality AC voltage generation. Simulation results confirm stable operation, fast dynamic response, a voltage THD below 4%, and overall efficiency above 95%, demonstrating the suitability of the proposed architecture for future power barge and port electrification applications. Full article

Maintaining frequency stability in modern multi-area interconnected power systems has become increasingly challenging due to the stochastic nature of wind power and reduced effective system inertia. Under these dynamic conditions, traditional fixed-gain PID controllers frequently fail to provide robust regulation. To address this limitation, this study proposes and evaluates a practical model-free secondary control strategy for multi-area Load Frequency Control (LFC). The proposed hybrid MFAC–PID framework integrates an incremental model-free adaptive control (MFAC) law with a low-gain incremental PID damping term. This combination leverages real-time input–output data to determine primary control actions without relying on an explicit plant model, while the PID component supplies supplementary damping based on recent control errors. Furthermore, the controller utilizes online pseudo-gradient estimation to dynamically adapt to stochastic wind fluctuations and $\pm 5\%$ parametric uncertainty. Simulation results demonstrate that the hybrid design substantially enhances Area Control Error (ACE) regulation. Under wind-disturbed conditions, it reduces the aggregated Integral Absolute Error ($IA{E}_{total}$) from 92.76 to 41.10, representing an improvement of over 50% compared with the fixed-gain PID baseline. Additionally, the controller maintains a low computational overhead of 0.306 milliseconds per control cycle. These findings indicate that the hybrid MFAC–PID structure provides a robust, computationally efficient solution for real-time Automatic Generation Control (AGC) in renewable-integrated multi-area power grids. Full article

Dynamic characterization of DC–DC power supplies typically requires dedicated dynamic voltage sources and electronic loads, which are often expensive and not readily available in low-cost laboratory environments. This creates a need for simple and flexible solutions capable of performing reliable line and load transient tests without complex auxiliary hardware. This paper presents a cost-effective technique for the dynamic testing of DC–DC power supplies, which can be applied with high versatility to both line and load transient testing. It is shown that injecting a perturbation signal into the feedback loop of a standard DC–DC regulator enables the regulator to operate either as a dynamic voltage source or as a dynamic electronic load, thus supporting both transient and small-signal AC characterization of a power supply under test. Analytical guidelines are provided to determine the static operating conditions and the achievable bandwidth of regulators operating in Dynamic Source Mode (DSM) and Dynamic Load Mode (DLM). The impact of voltage-mode and current-mode control strategies, as well as different error amplifier implementations, is investigated. Experimental line and load transient tests are carried out on interconnected switching and linear power supplies using Texas Instruments PMLK Series BUCK, BOOST, and LDO boards operating from 3.6 W to 36 W, with crossover frequencies up to 20 kHz. Measured injection gains and transient responses confirm the analytical predictions and demonstrate that FIT provides a simple, reliable, and cost-effective solution for dynamic testing of low-power DC–DC converters. Full article

Stable circumstances and an improved voltage profile need power compensators integrated with energy storage elements in AC power systems. The control of these compensators is of paramount importance for obtaining high accuracy, reliability, and better system dynamics, which involves careful controller design considerations and small-signal analysis. This paper focuses on the use of a static synchronous compensator (STATCOM) and supercapacitor energy storage system (SCESS) for achieving voltage stability, grid support, and better system dynamics. After the primary load is shifted to the grid, real power assistance is promptly injected into the AC grid to enhance the DC-link voltage, as well as the grid voltage, and reduce supply current from the grid using a vector control technique. The SCESS is handled with the help of a bidirectional DC–DC converter, which facilitates charging and discharging during boost and buck operations, respectively. Using small-signal modeling, the stable system is designed to obtain a reliable and stable output, which is confirmed by the systematic simulations and experiments. Full article

Local renewable energy microgrids in remote regions are typically characterized by high renewable energy penetration and weak grid-interconnection channels. These features lead to insufficient inertia and poor stability in both the microgrid and the AC main grid, with a failure to meet the power supply demands of microgrid loads. Conventional grid-forming converters or flexible interconnection devices have limited optional capabilities, making it challenging to comprehensively address these issues. This paper proposes a grid-forming energy-storage-based flexible interconnection system (GFM-ESFIS) which integrates the flexible interconnection converters with energy-storage units to fully meet the stability and power supply reliability requirements of the microgrid–main grid interconnection system in remote regions. Key steady-state and transient control strategies are analyzed and designed for the GFM-ESFIS. Simulations based on MATLAB/Simulink 2024a and hardware-in-the-loop experiments based on RT-LAB verify the effectiveness of the proposed system and control strategies. Compared with conventional schemes, the proposed system can operate flexibly in series or parallel modes, realizing multiple capabilities including dual-terminal grid-forming support, fault ride-through control, power flow regulation, operation mode transition, and black start. It holds significant application value in reducing grid investment costs and improving the power supply reliability of microgrids in remote regions. Full article

This paper proposes a novel, dual-output, hybrid-clamped, quasi-five-level inverter (DO-HC-FLI) topology, capable of providing two independent AC voltage outputs with adjustable frequency and amplitude. Derived from a dual-output, active, neutral-point-clamped, three-level inverter, the proposed topology introduces three additional switches per phase to create dynamic switching paths. This expands the available range of DC-side voltage outputs and significantly improves the utilization rate of the DC–link voltage. Additionally, by adopting an asymmetric DC–link voltage configuration, the output line voltage levels of the conventional four-level inverter are increased to a number comparable to that of a five-level inverter. The front-end stage employs a hybrid series-parallel architecture, integrating dual Buck circuits with DC power sources. This configuration supplies the subsequent inverter stage with DC voltage levels at an optimal asymmetric ratio. In conjunction with a dual-output space vector pulse width modulation (SVPWM) strategy, the proposed system can collaboratively optimize the output voltage level characteristics of the inverter stage. Furthermore, a comprehensive analysis and comparison with other multilevel inverters are presented to demonstrate the superiority of the proposed topology. Finally, simulations and experiments are conducted to validate the effectiveness and feasibility of the proposed topology and modulation strategy. Full article

Conventional multi-channel ultrasonic motor (USM) drive systems commonly adopt a one-motor–one-driver architecture, in which each drive channel requires an independent isolated power supply and inverter stage. As the number of motors increases, the system volume and structural complexity grow significantly. To address this issue, this paper proposes a shared DC-bus multi-channel drive architecture for traveling-wave USM. In the proposed scheme, multiple half-bridge power stages are connected in parallel to a common high-voltage DC-bus to achieve centralized energy supply and distributed driving. A DC-side midpoint reference network is introduced to establish an AC voltage reference under a unipolar DC supply, while an independent series matching inductor is employed in each channel to shape the half-bridge output into a quasi-sinusoidal motor-terminal voltage through resonant filtering. Based on the equivalent electrical model of the USM, a unified analytical model is established to analyze the voltage formation mechanism under shared DC-bus conditions. Time-domain simulations and experimental tests are carried out on a two-channel prototype operating at a 150 V DC-bus and a 40 kHz switching frequency. The results demonstrate stable quasi-sinusoidal output voltages, preserved phase consistency, and limited inter-channel coupling during parallel operation. Compared with conventional independent-supply solutions, the proposed architecture achieves an approximately 27% reduction in overall system volume for a three-motor configuration, demonstrating good scalability for compact multi-channel USM drive systems. Full article