Search Results (530)

Partial agricultural production loads exhibit significant temporality. The concentrated access of temporary loads can easily trigger operational challenges in distribution networks, such as heavy overload, terminal voltage violations, and increased network losses. To address these issues, this paper proposes a coordinated dispatch strategy for multiple flexible resources to cope with temporary loads. First, combining the operational characteristics of motor-pumped well loads, a refined model for motor-pumped well loads is constructed to fully exploit their regulation potential as flexible loads. Second, considering the supporting role of mobile energy storage systems (MESS) for heavy overload distribution networks, a spatiotemporal dispatch model for MESS is established. Then, aiming to minimize the total system operating cost, an economic dispatch model coordinating multiple flexible resources, including MESS, distributed generators (DG), and flexible loads, is developed. The original non-convex problem is transformed into a mixed-integer second-order cone programming problem using Second-Order Cone Relaxation (SOCR) method for efficient solution. Finally, the effectiveness of the proposed strategy is verified on an improved IEEE 33-bus system. Full article

The electrification of the automotive industry and the lightweighting of aerospace equipment demand high-efficiency centrifugal pumps for compact spaces. A novel centrifugal pump incorporates an integrated impeller-motor rotor design, achieving a more compact footprint and higher power density. However, research is scarce on the radial clearance between the rotor and casing. This study presents a comprehensive investigation of the internal flow dynamics, combining numerical simulations with experimental validation. A significant reduction in fluctuation amplitude for pump efficiency, head coefficient, and frictional loss rate occurs when the clearance ranges from 1.0 to 1.5 mm. Within clearances of 0.75 to 1.5 mm, complex vortex systems emerge in the radial clearance, inducing diverse circumferential high-speed zones. Pressure fluctuations within the radial clearance are predominantly governed by the blade passing frequency. At a clearance of 1.5 mm, the rotational harmonic amplitude at monitoring points exceeds the blade passing frequency amplitude by a factor of 1.9, while the average pressure fluctuation intensity at other points increases significantly by 36.9%. An optimal clearance of 1.25 mm achieves a balance between flow characteristics and energy consumption. This research provides practical insights for optimizing pump energy performance and operational stability. Full article

Medium voltage induction motors (MVIM) are a key component of numerous industries, such as water treatment plants, sewage discharge stations, and chilled water systems. The starting process for these MV motors is critical as it is associated with a major impact on both motor lifetime and power grid quality. In this article, a proposed modified and comprehensive starting scheme of MV three-phase induction motors driving pumps for water stations is introduced. Firstly, the starting performance and its impact on power grid quality will be discussed when all motors are normally started with direct on line connection (DOL), which is already the normal established status. A modified starting scheme based on an optimized coordination of motor starting methods in addition to variable voltage variable frequency drive (VVVFD) drive and control implementation will be discussed. A transition between the starting of variant MV induction motors as well as the starting event coordination principle will be discussed to improve the power quality relative to the obligatory time shift required for the operation. The coordination is based on an algorithm implementation which is achieved using different optimization concepts based on artificial intelligence techniques, properly conducting the transition time in addition to the power delivered by the inverter unit rather than determining the number of DOL and VVVF-implemented motors. A comparison between using the optimized VVVFD soft-starting and the proposed modified scheme is performed, focusing on the power quality improvement rather than optimizing the cost function. The modified scheme is simulated using ETAP power station for brief analysis and study of load flow rather than the complete inspection and power quality assessment. Full article

A high-speed magnetic pump rated at 7800 r/min was studied. A numerical model was established, and a hydraulic, vibration, and noise testing system was set up to conduct flow simulations, noise, and vibration experiments at different speeds. The results show that increasing speed leads to a higher pressure difference between the pump chamber and the cooling circuit. Meanwhile, the turbulent kinetic energy at the impeller outlet increases. Despite an increase in energy loss, the loss ratio decreases, and overall efficiency improves. The internal flow noise collected by the outlet hydrophone mainly comes from Rotor–Stator Interference (RSI), and it can sensitively capture changes in rotational speed. The dominant frequency of the outlet noise agrees well with the blade frequency calculated from the set speed, with a maximum deviation of 0.26%. As the speed increases, the overall sound pressure level (OASPL) at the inlet and outlet and the Root Mean Square (RMS) acceleration values at the outlet and pump body generally increase, while the acceleration at the motor base shows a decreasing trend. The conclusions are helpful for the design and optimization of rotary machinery such as high-speed magnetic pumps. Full article

Heavy-duty forklifts possess substantial kinetic energy during braking, which is currently wasted due to a lack of recovery in conventional systems. To ensure braking safety, an electro-hydraulic–mechanical compound braking system is necessary. However, the uncoordinated distribution between regenerative and mechanical braking torque leads to braking torque fluctuations, compromising safety, comfort, and recovery efficiency. This paper constructs a parallel hydraulic hybrid power system for heavy-duty forklifts based on a four-quadrant pump/motor, enabling braking energy recovery and reuse via the pump/motor and an accumulator. A compound braking strategy based on the ideal braking force distribution and multi-sensor information fusion is proposed. The system incorporates various sensors, including pressure, speed, flow, and pedal displacement sensors, to monitor system status and driver intention in real time, providing precise data for coordinated control. Feasibility is verified through AMESim simulation and real vehicle tests. The control system based on sensor feedback maximizes braking energy recovery while ensuring braking safety and comfort, achieving a 12.2% energy-saving rate and significantly improving the vehicle’s economy and range. Full article

In order to reduce the energy consumption of a reverse osmosis seawater desalination system, a study was conducted on the port plate pair that affects the efficiency of the integrated seawater desalination power recovery motor pump. Based on its structural characteristics, a reverse thrust model of the port plate pair was established. A fluid–solid heat multi-field coupling simulation platform was built to study the temperature characteristics of the port plate pair under different conditions. A design method was proposed to use the local temperature characteristics of the port plate pair as the range of residual compression force coefficient values. When the residual compression force coefficient is determined to be 1.05, the compression force of the port plate pair is 33,019 N, the power loss is 307 W, and the temperature reaches 45.1 °C. The simulation accuracy is verified to be 97.31% through experiments. This solved the power loss and local high-temperature problems of the port plate pair and improved the efficiency of the integrated seawater desalination power recovery motor pump. Full article

This paper presents an efficient stand-alone photovoltaic water pumping system (PVWPS) intended for agricultural irrigation applications, operating without energy storage. The system employs a three-phase induction motor supplied by a three-level neutral point clamped (NPC) inverter. The proposed control strategy integrates the advantages of two distinct controllers to enhance both energy extraction and drive performance. On the photovoltaic side, a fuzzy logic-based maximum power point tracking (MPPT) algorithm is implemented to ensure continuous operation at the global maximum power point under rapidly varying irradiance conditions. On the motor drive side, a direct torque control (DTC) scheme is combined with the multilevel NPC inverter to regulate electromagnetic torque and stator flux. The use of a multilevel inverter significantly mitigates the inherent drawbacks of conventional DTC, notably torque and flux ripples, as well as stator current harmonic distortion. The overall control architecture maximizes power transfer from the photovoltaic generator to the pumping system, resulting in improved dynamic response and energy efficiency. The proposed system is validated through detailed MATLAB/Simulink simulations under abrupt irradiance variations and a realistic daily solar profile corresponding to August conditions in Kairouan, Tunisia. Simulation results demonstrate substantial performance improvements, including an 88% reduction in torque ripples, a 50% decrease in flux ripple, a 77.9% reduction in stator current THD, and a 33.3% enhancement in speed transient response compared to conventional DTC-based systems. Full article

This paper presents a model-free Best Efficiency Point (BEP) tracking method for centrifugal pumps without head measurement or manufacturer-provided characteristic curves. The proposed approach combines a discrete finite-difference extremum-seeking control (ESC) scheme with an efficiency approximation proxy derived from measurable variables—namely, flow rate and electrical power. Under constant head conditions, the proxy function is analytically shown to be proportional to the true pump efficiency, enabling real-time BEP localization using only motor feedback signals. The ESC algorithm employs a sign-based gradient rule with adaptive step-size reduction to achieve rapid and stable convergence without mathematical models. A Python-based simulation using a Schneider SUB 15-0.5cv pump demonstrates that the method can track the BEP with negligible steady-state error (less than 0.1% efficiency deviation). The proposed framework offers a cost-effective solution for efficient optimization for mobile pumping applications in large water resources where installing head sensors is impractical. Full article

To address the issues of large overshoot, slow response, poor stability, and suboptimal control performance of traditional PID algorithms caused by the nonlinear relationship between the rotational speed and output flow rate of micro screw pump motors, this study proposes a PID parameter optimization method based on an improved spider wasp optimizer algorithm. First, this method incorporates the Tent chaotic mapping into the Spider Wasp Optimizer algorithm (SWO) to enhance initial population diversity, integrates differential evolution strategies to accelerate convergence, and employs Levy flight to boost local search capabilities, thereby balancing global exploration with local exploitation. Subsequently, comparative validation using 12 benchmark functions demonstrates that the improved algorithm (ISWO) outperforms SWO, PSO, SA, GOOSE, and CPO across metrics including mean, standard deviation, and Wilcoxon rank-sum test. Finally, integrating ISWO with PID control yields ISWO-PID, applied to a screw pump model. Simulation results demonstrate superior optimization efficiency and control performance: runtime was reduced by over 60% compared to benchmark algorithms, with enhanced system robustness and adaptability. Full article

Disk-type electromagnetic direct-drive centrifugal pumps have broad application prospects in fluid transport due to their compact structure and seal-free design. However, the significant axial force caused by pressure imbalances on both sides of the impeller severely affects the operational stability and the service life of the pump. This study selected the IS50-32-160 pump as the research object, seeking to optimize various balance hole structures for reducing axial force and enhancing pump efficiency. Using ANSYS-ICEM 2022 for hydrodynamic performance mesh generation and Fluent for numerical simulations, we systematically analysed 24 balance hole models with varying diameters, lengths and aperture gradient profiles to evaluate their effects on pump hydrodynamic performance, motor air-gap pressure, leakage rate and axial force. The results demonstrate that the balance hole diameter predominantly affects axial thrust, whereas the length exhibits negligible influence. Specifically, when the diameter was increased from 0 to 8 mm, the axial force dropped sharply, from 703.45 N to 125.57 N. The most pronounced reduction, of 54.7%, occurred within the 3 to 5 mm diameter range, after which the decline rate significantly slowed. In contrast, increasing the length from 84 to 100 mm only caused a marginal 4.08% rise in axial force, from 307.22 N to 320.30 N. The diverging balance holes, characterized by a linear diameter expansion from the shaft end toward the impeller side, achieved continuous and stable pressure distribution. This design not only effectively mitigated axial force but also prevented abrupt pressure fluctuations at the shaft end. The study confirms the feasibility of improving pump performance through balance hole optimization and provides a theoretical foundation for designing disk-type electromagnetic direct-drive centrifugal pumps. Full article

The use of photovoltaic (PV) water pumping technology offers a viable and sustainable alternative to conventional diesel-driven pumping systems. In PV-based pumping installations, the elimination of bulky transformers significantly reduces the overall system size and weight, which is particularly advantageous for rural and remote irrigation applications. However, removing the transformer can result in high common-mode voltage (CMV) when the induction motor is controlled using a direct torque control (DTC) scheme. This elevated CMV induces leakage currents that may damage the motor, compromise system reliability, and pose potential safety hazards. To ensure a more compact and safer PV pumping system, this paper introduces an improved DTC-based control strategy for induction motors driven by transformerless multilevel PV inverters. The proposed approach effectively suppresses leakage current by mitigating its main source, CMV, while maintaining the simple structure and dynamic performance inherent to conventional DTC. Two new look-up tables (LUTs) are developed to control the stator flux and electromagnetic torque while simultaneously eliminating leakage current. The first method, termed zero-medium vector DTC (ZMV-DTC), employs both zero and medium voltage vectors from the space vector diagram. The second, referred to as medium vector DTC (MV-DTC), utilizes only medium vectors. Numerical simulation results validate the feasibility and superior performance of the proposed algorithms in terms of leakage current suppression. Compared with a conventional DTC (C-DTC) scheme that is designed to limit the CMV, the proposed DTC algorithms achieve a much stronger reduction in the CMV, confining its amplitude to only a few volts, instead of the levels ±V_dc/6 typically produced by the C-DTC. As a result, the leakage current is effectively eliminated, ensuring safer and more reliable operation of the system. Full article

As the electrification of the automotive industry accelerates, the importance of small-scale motors used in applications such as HVAC systems and water pumps is growing. To design small motors that exhibit high efficiency and high output within limited spaces, applying axial flux motors (AFMs) instead of conventional radial flux motors (RFMs) can maximize the power density within the same volume, offering advantages in both weight reduction and miniaturization. This study proposes an optimized end-turn layout design to mitigate back-EMF imbalance in AFMs utilizing PCB stators. Optimization results demonstrated that the structure employing a non-adjacent end-turn layout with equalized average end-turn heights (BCAACB type) exhibited the best performance in terms of average resistance and phase resistance variance, effectively mitigating back-EMF imbalance. The validity of the optimized end-turn structure was verified through finite element analysis (FEA). The analysis confirmed that the motor’s back-EMF balance was improved, and the magnitude of phase resistance was reduced. This reduction led to lower copper loss, thereby increasing overall efficiency. Furthermore, the variance in resistance for each phase was minimized, resulting in enhanced electrical balance. The results of this study are expected to contribute to enhancing the applicability of PCB stators in small motor design. Full article

Plasma power supplies find extensive applications across industrial, energy, environmental, and medical domains. This study addresses limitations of conventional plasma power supplies, including high harmonic current content, neutral-point potential imbalance, and manufacturing complexity. A novel design approach for high-frequency, high-voltage plasma power supplies is proposed, based on three-level sinusoidal pulse width modulation (SPWM) technology. First, the design distinctions between the input-side Boost power factor correction circuit and Diode Rectifier circuits are analyzed. Subsequently, an integrated SPWM driver-controller architecture and a design methodology for high-frequency transformers are introduced. A single-phase three-level SPWM modulation strategy is then presented. Based on this modulation technique, a high-frequency, high-voltage plasma power supply prototype incorporating air pumps and rotary motors was developed. Experimental validation demonstrated stable generation of plasma gas at a frequency of 25 kHz, with an output voltage of 10.79 kV and an output power of 1.75 kW. Results indicate that the refined power supply enhances electrical utilization efficiency, resolves neutral-point imbalance issues, and simplifies manufacturing through its integrated driver-controller design. This work offers a valuable reference for advancing high-frequency, high-voltage plasma technologies. Full article

Potato harvesters operating in hilly and mountainous areas are often subjected to harsh working conditions such as high temperature, sun exposure, and high torque excavation. Due to the fluid sealing characteristics, closed loop hydraulic systems are prone to high temperatures during long-term continuous operation, resulting in a decrease in fluid viscosity, poor lubrication, severe wear, and power attenuation. This study investigates the hydraulic system of potato harvesters in hilly terrain, systematically analyzing its energy transfer process and identifying key heat-generating components. Based on an optimization strategy that extends the flow path of high-temperature fluid within the tank, four distinct tank designs were proposed. Computational fluid dynamics (CFD) and thermodynamic simulations were conducted to evaluate their heat dissipation performance, followed by full-machine validation testing. Results indicate that the walking and lifting systems are the primary heat sources. The dual pump contributes the highest proportion of heat (52.07%), followed by the walking motor (20.54%). The heat exchanger dissipates 72.91% of the heat, while the hydraulic oil tank accounts for 14.93%. Among the four tank designs, Tank 0 exhibited the fastest temperature rise, reaching a thermal equilibrium of 83.27 °C, whereas Tank 1 had the lowest equilibrium temperature (78.62 °C). Heat dissipation efficiencies for the tanks were 7.8%, 12.9%, 10.1%, and 11.6%, respectively. The residual gas volume fraction decreases significantly as the bubble diameter increases, due to the higher buoyancy and faster rise velocity of larger bubbles, which leads to shorter residence times and more effective precipitation. Tank 1 achieved the lowest equilibrium temperature, indicating the best thermal efficiency. Tank 3 showed the best overall degassing performance, particularly for medium-to-large bubbles. Tank 1 was selected as the optimal final design because it could offer an excellent balance, with very good cooling and competitive degassing (especially for small bubbles). Field tests confirmed a 14.8% reduction in thermal equilibrium temperature for Tank 1 (75.6 °C) compared to Tank 0 (88.7 °C). Simulation and experimental data showed strong agreement, with maximum errors of 9.2% for return fluid temperature, 12.7% for cooling return fluid temperature, 9.7% for pressure, and 8.5% for flow rate. Average errors remained below 8.4% for pressure and 7.6% for flow rate. These results validate the accuracy of the simulation model and the effectiveness of the tank optimization method. Full article

With the significant increase in the number of motor vehicles in plateau regions, the adaptability and reliability requirements of diesel engines operating under high-altitude and cold conditions have become increasingly critical. In this study, a one-dimensional transient simulation model of the overall engine lubrication system was developed based on a physical experimental prototype. The multiphysics-coupled lubrication system was numerically modeled and analyzed, with particular emphasis on elucidating the influence mechanisms of high-altitude and cold environments on the startup performance of diesel engine lubrication systems. System responses under different ambient pressures (0.88 bar, 0.92 bar, 0.96 bar, and standard atmospheric pressure) and oil temperatures (30 °C, 55 °C, and 100 °C) were systematically investigated. In addition, variations in the opening degree of the oil pump pressure relief valve (closed, 4%, 30%, 60%, and 100%) were incorporated to reveal the governing effects of high-altitude and cold environments on lubrication system startup behavior. The results indicate that under high-altitude and cold conditions, the decrease in oil temperature is the dominant factor and exerts the most significant influence on the steady-state oil pressure and flow rate of the lubrication system. Variations in ambient pressure lead only to an equivalent shift in absolute oil pressure, with negligible effects on relative oil pressure, steady-state flow rate, response time, or filling rate. However, a reduction in atmospheric pressure leads to a decrease in the peak oil flow rate at the outlet of the oil pump. The opening degree of the pressure relief valve exhibits a nonlinear influence on the startup performance of the lubrication system, and significantly decreases the oil filling rate. This study innovatively develops a lubrication system performance prediction model under high-altitude, low-pressure, and low-temperature conditions. Calibrated using vehicle road-test data, the model quantifies for the first time the relative contributions of the three key factors to start-up lubrication performance, thereby providing a clear decision-making framework and prioritized improvement directions for the reliability-oriented design and safety threshold calibration of lubrication systems in high-altitude diesel engines. Full article