Instantaneous Power Research Articles

Experimental and CFD Assessment of Harmonic Characteristics of Point-Absorber Wave-Energy Converters with Nonlinear Power Take-Off System

The wave-energy excitation of point absorbers is highly associated with their resonant movement, and harmonic characteristics are of increasing concern in affecting resonance. However, the commonly used linearized power take-off (PTO) systems underestimate the impact of harmonics. The purpose of this study is to address the knowledge gap in assessing the contribution of hydraulic PTO systems to higher harmonic wave loads and velocities. In the present work, higher harmonics in point-absorber wave-energy converters (PA-WECs) with hydraulic power take-off (PTO) systems are investigated through both experimental and computational fluid dynamics (CFD) methods. The fast Fourier transform is used to decompose the high-order harmonics. To account for the influence of nonlinear wave–wave interaction on harmonics, the isolated PA-WEC is used as a basis for comparison with the paired PA-WECs. The influence of wave steepness is also estimated at two resonance periods. Results indicate that the additional resonance of the paired PA-WECs may be attributed to the harmonic wave loads at longer wave periods. Harmonic wave loads of paired PA-WECs typically have a more substantial impact and increase more rapidly with increasing wave steepness compared to isolated PA-WECs. Furthermore, as the wave steepness increases, there are significant enhancements in both the harmonic wave loads and heaving velocity, which strongly correlate with the instantaneous maximum hydraulic power. Consequently, our study will contribute to enhancing the maximum power output in the design of future point absorber arrays.

A reconfiguration method for photovoltaic array of stratospheric airship based on multilevel optimization algorithm

Reducing the mismatch loss to increase the output power of the photovoltaic (PV) array is crucial for extending the flight time of stratospheric airships. This paper presents a reconfiguration system for PV arrays based on a switch matrix designed for stratospheric airships. The proposed system employs a multilevel optimization reconfiguration algorithm that combines smart choice, greedy, and Munkres' assignment algorithms. Simulations were conducted under single working conditions, full-day sunlight cycles, and full-year PV array reconfigurations, respectively. The results demonstrated that the reconfigured PV array significantly improved the output power with a smooth PV curve. The instantaneous power under extreme working conditions could be increased by 50.1%. Furthermore, during the 7-day simulation process, the average daily power output of the PV array increased by 14.68%, whereas the output fluctuation during circular cruising was reduced. The reconfiguration system offers greater advantages during months with weak irradiance in high-latitude regions, where the daily output power of the PV array can be increased by up to 24.46%. This significantly reduces the installation area and weight ratio of a stratospheric airship PV array.

Application of instantaneous power draw analysis to investigate the impact of microwave heating on kimberlite ore crushing

Traditional crushing methods rely on a limited number of existing natural cracks as the source of crack propagation to break ore particles. Microwave-assisted crushing, on the other hand, facilitates the crushing process by inducing intergranular and transgranular cracks in ore particles. This not only reduces the energy consumption of the crusher but also improves the production rate of the process. In this study, microwave-assisted crushing of kimberlite ore is investigated ingeniously by examining the change in power draw trends to understand better the roles of larger cracks and smaller cracks induced by microwave treatment. An innovative calculation method is proposed to enable continuous monitoring of power draw instead of average power consumption. This method establishes a quantitative standard for exploring ore crushing capacity and the mechanisms of rock samples. From this study, the cumulative specific crushing energy and crushing time reduction in microwave-treated samples can be attributed to three distinct mechanisms. Firstly, the preferential generation of comparatively bigger cracks on large particles improves the breakage rate within the accumulating zone. Secondly, the generation of sufficient comparatively smaller cracks on large particles contributes to a lower peak net power amplitude. Lastly, the well-distributed generation of cracks across all particle sizes results in a shorter declining zone and an overall improvement in crushing time. The most significant reduction in both crushing energy and crushing rate is observed with the high microwave energy input. However, even at lower microwave energy inputs, substantial reductions in specific crushing energy and crushing time can still be achieved. This study demonstrates that the proposed method can be applied to other comminution systems, whether with or without microwave assistance.

UAV instantaneous power consumption prediction using LR‐TCN with simple moving average

SummaryThe usage of multi‐rotor unmanned aerial vehicles (UAVs) has rapidly increased in a variety of industries recently, which has caused a quick rise in the quantity of research works on the topic. Remaining battery life prediction, anomaly detection and instantaneous power consumption prediction are among the topics that attract the most attention of researchers. This article presents the development and utilization of a modified temporal convolutional network (TCN) model, a commonly employed approach for anomaly detection and instantaneous power consumption prediction in unmanned aerial vehicles (UAVs). The first modification to the TCN model was to use the Leaky ReLu activation function in place of the rectified linear unit (ReLu) activation function from the original TCN model. In the next step, instantaneous power consumption prediction for UAVs was performed by using the data obtained from both sensors and simple moving average (SMA) algorithm. As a result of the tests performed with the created simulation setup, it has been clearly shown that the proposed method gives better results compared to other deep learning models used for comparison with the lowest RMSE of 0.0496.

COHERENT DEMODULATION OF SYNCHRONOUS MUTUALLY NOT ORTHOGONAL DIGITAL SIGNALS WITH MANIPULATION IN THE MINIMUM SHIFT KEYING

The article presents the synthesis of a mathematical model of the compensation procedure for coherent demodulation of synchronous mutually non-orthogonal digital signals with manipulation in the minimum shift keying. In the absence of interference this procedure degenerates into the procedure of classical coherent demodulation of digital signals with manipulation in the minimum shift keying. With a significant excess of the instantaneous power of interference over the instantaneous power of useful digital signals with manipulation in the minimum shift keying the immunity of reception of the latter approaches the immunity of reception in a channel with additive white Gaussian noise without interference. This mathematical model can be used in the development of modem compensators that ensure repeated use of the frequency resource, as well as in the development of promising interference -protected radio communication devices.

Numerical investigation of the power performance of a wave energy converter comprising a multi-body power take-off

This article presents a wave energy converter exploiting the pitch of a floating body moored to the seabed. When the floating body tilts under the action of an incoming wave, a movable mass, placed inside the hull, moves relative to the floating body and actuates an electrical generator. Most devices of this type have the drawback that the moving mass sequentially accelerates, slows down, stops and then repeats this sequence in the opposite direction. This generates an irregular instantaneous power output. The proposed concept consists of (at least) two eccentric bodies having the same mass and revolving atopposite speeds around a vertical axis. In this « counterrotating » solution, the oscillations of the float result in the continuous circular motion of the direct-drive PTO, though the global centre of gravity of the eccentric bodies moves back-and-forth along the symmetry axis of the device. If the eccentric bodies move at constant speed, their global centre of gravity moves in a sinusoidal manner along its pathway. The present study aims to investigate, through modelling and numerical simulations, the influence of the main parameters, such as the phase and the PTO mass moment, on the performance of a counter-rotating device exposed to waves of various heights and various wavelengths. Optimal phase and mass moment are determined numerically. The resulting output power is close to the theoretical maximum power that can be harvested by the floating body.

Research on improved Harmonic current detection method based on SOGI-PLL instantaneous reactive Power

In view of the traditional instantaneous reactive power detection has low anti-harmonic interference ability, poor real-time performance, and insufficient accuracy when the power grid frequency fluctuates, this paper improved the detection link. The working principle of single-phase harmonic detection is analyzed, and the improved second-order generalized integrator is added to make the phase-locked loop detect the voltage phase accurately and efficiently. Based on the comparison and compensation simulation results of the active compensation device, the quality of grid-connected current of the inverter is improved effectively, and the precision of phase locking is increased.

A Stator Internal Short-Circuit Fault Protection Method for Turbo-Generator Based on Instantaneous Power Oscillation Ratio

For large turbo-generators, the longitudinal differential protection can only reflect the stator internal inter-phase short-circuit fault, and cannot reflect the inter-turn short-circuit fault. The protection methods for inter-turn short-circuit faults have the problem of low sensitivity, such as the longitudinal zero-sequence voltage protection and the negative sequence component-based protection. Therefore, a stator internal short-circuit fault protection method for turbo-generator based on instantaneous power oscillation ratio (IPOR) is proposed in this paper. The instantaneous power variation of the generator before and after the fault is analyzed, and the IPOR is calculated by using the balanced power component and the oscillatory power component. Then, the method to judge whether the generator has an internal short-circuit fault based on the amplitude and phase of IPOR is proposed. The experimental results verify the effectiveness of the proposed protection method, which has a high sensitivity to the inter-turn short-circuit faults with a small turn difference. The protection is stable and does not malfunction during the system oscillation. In addition, the action time of the protection method does not exceed 1.5 power frequency cycles under various working conditions, which can meet the speed requirements of generator protection.

Determination of required instantaneous power reserve for power system inertia enhancement, based on the unit commitment

Determination of required instantaneous power reserve for power system inertia enhancement, based on the unit commitment

A time-frequency method for induction motor fault feature extraction using instantaneous power signals

To solve the issue that the characteristic frequencies of the broken rotor bar fault (BRBF) are always submerged by the fundamental component during the stator current spectrum analysis in light loads, this paper proposes an effective approach based on the instantaneous power signal and the local maximum synchrosqueezing transform (LMSST). By multiplying the current and voltage, the instantaneous power signal can provide more fault features and enhance fault component amplitudes. The LMSST method is used to obtain a time-frequency analysis with more concentrated energy, and more fault characteristics are extracted from the reconstructed signal, which helps to accurately identify the motor BRBF.

Efficiency Optimization and Resilience Improvement in Wireless Motor System With Flexible DC-Link Voltage Regulation

This paper proposes a novel dc-link voltage regulation (DCVR) strategy for the series-series compensated wireless motor (SSWM) system. The steady-state voltage control is presented to optimize the system efficiency and the feedforward voltage boost control is proposed to improve system resilience. The rated capacity identification (RCI) scheme is proposed to design proper parameters for the SSWM system. To achieve steady-state voltage control, the system efficiency characteristic is analyzed in detail and the efficiency optimization can be achieved without an auxiliary dc/dc converter. The influence of impedance matching, the power capacity of the system, and overmodulation of the motor drive are all investigated. Then, the dynamic model of the system is established to analyze the stability of dc-link voltage. In the proposed feedforward voltage boost control, the dc-link voltage is boosted according to the motor operation state to increase the instantaneous power capacity. The dc-link voltage stability is improved and the system resilience is enhanced against power disturbance. Besides, at the end of the acceleration process, the dc-link voltage is smoothly adjusted to the optimal dc-link voltage. The effectiveness of the proposed RCI scheme and DCVR strategy is verified by experiments on a three-phase wireless permanent magnet synchronous motor platform.

GNSS-Based Estimation of Average Instantaneous Power Consumption in Electric Vehicles

Several countries are currently leading the challenge of replacing internal combustion engines (ICE) in vehicles by electrically powered ones, mainly motivated by the goal of reducing the dependence on oil and the carbon footprint. However, the autonomy of electric vehicles (EVs) remains significantly lower than their ICE counterpart: it depends on the amount of energy stored and its rate of utilization, characterized by the instantaneous power consumption (IPC). Although IPC can be measured from on-board voltage and current sensors, in route planning applications it is of paramount importance to generate prior estimates from other sources of information, such as the mass of the vehicle, its velocity, acceleration, aerodynamic, and rolling resistances (among other vehicle and terrain parameters). In this work, we propose the estimation of average IPC for a given path, using only localization information provided by a global navigation satellite system antenna, at different levels of errors. Our work is experimentally validated with an EV on the road, achieving on average a 99.7% of power estimation accuracy for a localization error of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm 1.5$</tex-math></inline-formula> m –as best case– and 73.6% accuracy for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm 8.6$</tex-math></inline-formula> m of localization error—as worst case. These results encourages us to use only position data to estimate average IPC of EVs, avoiding the need of placing extra sensors into the vehicles.

Textile-integrated MoS2-PDMS single electrode triboelectric nanogenerator for vibrational energy harvesting and biomechanical motion sensing

With the increasing demand for portable electronics, durable and flexible textile-based single electrode triboelectric nanogenerators (TENGs) have received a significant amount of attention. In this work, we have proposed a flexible textile based single electrode TENG (STENG) composed of MoS2-PDMS composite film. The effect of the concentration (0–10 wt%) of MoS2 in PDMS on the output performance of the as-fabricated devices was systematically studied. The STENG with a 6 wt% concentration of MoS2 exhibits the best output performance with an open-circuit output voltage, short-circuit output current density, and maximum instantaneous output power density of ∼ 320 V, ∼ 15.4 µA/cm2, and ∼ 3.2 mW/cm2, respectively. The enhancement in the output characteristics of the STENG can be explained by the formation of network of nanocapacitors, where the layers of MoS2 behave as electrodes and the insulating PDMS behaves as a nanodielectric. The powering capability of the as-fabricated STENG was tested by charging commercial capacitors and directly flashing 100 commercially available LEDs without any external charge storage component. The textile-based MoS2-PDMS composite is not only used as STENG, but also as a human motion sensor capable of detecting diverse human actions, including wrist bending, arm bending, and leg bending. As a result of its flexible structure, scalable manufacturing process, and ability to sense human motions, the developed MoS2-PDMS composite STENG has promising applications in self-powered wearable electronics and human-machine interaction.

A component sizing prediction study for a series hybrid electric vehicle based on artificial neural network

In the present study, the predictive tool based on an artificial neural network is developed by means of the experimental data of two series hybrid electric vehicles. The experiments have been conducted on different driving conditions, including highways, traffic, and combined driving conditions. Then, the artificial neural network is developed to predict an arbitrary series hybrid electric vehicle’s required power. The instantaneous required power is divided into dynamic and steady power to size the combustion engine, electric motor, and high voltage battery of the series hybrid electric vehicle. The effects of different ambient conditions (including ambient temperature and altitude), the inverter and high voltage battery efficiencies, and the coast-down coefficients on the components sizing of the series hybrid electric vehicle are then investigated in different driving conditions. The results revealed that the maximum instantaneous power of the electric motor is associated with rapid acceleration in low-speed conditions, and the suburban driving route determines the combustion engine’s maximum power. Notably, the Worldwide Harmonized Light-duty vehicles Test Cycle is the most comprehensive among the available driving cycles, and most of the components’ sizes are determined by this cycle except the combustion engine’s maximum power. It is also realized that the cycle-wise investigation can be summarized into the Isfahan-Tehran route and Worldwide harmonized Light-duty vehicles Test Cycle calculations.

Synergistic effect of unidirectional charge accumulation and electrostatic discharge: Simplified design approach for dramatic output enhancement of triboelectric nanogenerator

In the triboelectric nanogenerator (TENG) field, an innovative output enhancement strategy toward the ampere (A)-level and a broad design guideline to realize this strategy remain elusive. Herein, we propose self-enhanced electrostatic discharge triboelectric nanogenerator (SED-TENG) that has a simple design and mechanism to achieve ultrahigh current output performance. The SED-TENG based on the proposed synergistic effect between unidirectional charge accumulation and direct electron flow generated a peak voltage of approximately 2200 V, peak current of 7 A, and transferred charge of 50 μC in one cycle. The SED-TENG was optimized in terms of various design variables and circuit configurations by quantitatively comparing its peak and RMS outputs. The electrical output of the SED-TENG was investigated in various operating environments and under diverse conditions. Under a broad range of load resistances, the SED-TENG exhibited outstanding instantaneous and average output power characteristics. The SED-TENG can be utilized as ultrahigh performance energy harvesting tile, for example, the artificial grass-integrated SED-TENG generated stable outputs during walking and running. As practical applications, the SED-TENG was able to brightly illuminate 3000 LEDs and 56 W/108 W commercial fluorescent lamps, continuously operate three commercial sensor arrays without a time limit, furthermore, produce hydrogen/oxygen via water splitting.

Reduksi Harmonisa Pada Saluran Distribusi Tenaga Listrik Dengan Filter Daya Aktif

The large use of power converters in distribution lines causes poor power quality such as high produces harmonics in an electric power system that arises due to the operation of non-linear electrical equipment. The presence of harmonics in the power system distribution results in a very large loss in the system. In this paper had been done a simulation of power quality improvement through harmonic reduction using parallel active power filter. Active power filters work with control techniques based on the concept of instantaneous power to determine the amount of compensation currents that must be generated by the power compensator power circuit. The compensating current references generated by the control circuit are used by the hysteresis type controller to provide harmonic compensation arising. From the result of simulation using Simulink MATLAB, the harmonic value (THD) decrease caused by the 3 phase rectifier load on a distribution network which is used as case example. The harmonic value before compensated on the network is 27.85% at each phase, while after computing the harmonic value of the network decreases to 1,43% in R phase, 1,49% in S phase, and 1,34% in T phase.&#x0D;

Flexible Self-Powered Energy Systems Based on H2 O/Ni2+ Intercalated Nix V2 O5 ⋅ nH2 O.

The development of portable electronic devices has created greater demands for multifunctional energy integration systems. Self-powered systems have gained widespread interest because they can collect and storage renewable environmental energy and provide stable electricity to electronic devices. Herein, we developed a flexible self-charging energy system, involving textile-based zinc-ion hybrid (ZIHC) and triboelectric nanogenerator (TENG), which demonstrates wearable, compatibility, lightweight and can quickly harvest and store energy. Nix V2 O5 ⋅ nH2 O (NVO) loaded on carbon cloth (CC) with Ni2+ /H2 O ions intercalated as the cathode was assembled with activated CC to form a ZIHC, which has a voltage range of 2.0 V and capacitance value of 267.1 mF cm-2 as well as good charge and discharge rates and excellent cycling stability. At the same time, the NVO/CC can be assembled with PDMS to form a TENG achieving a maximum instantaneous power of 18.5 mW cm-2 . The device can be flexibly worn over the body to continuously harvest and store biomechanical energy and charge the electronic wristwatch successfully. This work demonstrates great convenience and promising practical applications as sustainable flexible energy system for portable electronic devices.

Design of Hydrostatic Power Shift Compound Drive System for Cotton Picker Experiment

To meet the working performance demand of cotton pickers, a hydrostatic power shift composite drive system design is proposed. This study aims to enhance the driving function of the cotton picker in various working conditions and improve its adaptability by combining a hydrostatic speed control system with a mechanical power shift structure. To achieve this, a single variable pump + double variable motor closed circuit is adopted. By adjusting the pump and motor displacement in stages, the driving speed of the cotton picker can be optimized for different working conditions. Additionally, the power shift mechanism is employed to increase the speed range and improve the transmission efficiency, enabling higher speeds to be achieved. Firstly, the main components of the composite drive system were calculated and selected, and then AMESim software was used for modeling and simulation analysis, and the results are as follows: When the cotton picker starts and picking operation stage variable displacement pump + fixed displacement dual motor speed control, the highest driving speed is 8.5 km/h. During the field and road transport operation stage fixed displacement pump + variable displacement dual motor speed regulation, the highest speed of 14.5 km/h was achieved in the field. When transferring to the road, the instant mechanical power shift speed and, the highest speed on the road was up to 27.5 km/h. Finally, the field experiment and speed ratio analysis of the drive system was conducted, and the average error of the experimental speed measurement was 0.588%. The speed ratio matching was in line with the design expectation. The results show that the hydrostatic power shift composite drive system designed in this study has good driving adaptability and can effectively meet the functions of cotton picker field picking, transport operation and road transportation in transit, which provides theoretical support for the design of cotton picker chassis drive system.

EEG Phase Can Be Predicted with Similar Accuracy across Cognitive States after Accounting for Power and Signal-to-Noise Ratio.

EEG phase is increasingly used in cognitive neuroscience, brain-computer interfaces, and closed-loop stimulation devices. However, it is unknown how accurate EEG phase prediction is across cognitive states. We determined the EEG phase prediction accuracy of parieto-occipital alpha waves across rest and task states in 484 participants over 11 public datasets. We were able to track EEG phase accurately across various cognitive conditions and datasets, especially during periods of high instantaneous alpha power and signal-to-noise ratio (SNR). Although resting states generally have higher accuracies than task states, absolute accuracy differences were small, with most of these differences attributable to EEG power and SNR. These results suggest that experiments and technologies using EEG phase should focus more on minimizing external noise and waiting for periods of high power rather than inducing a particular cognitive state.

Enerduino-pro: Smart meter led probe using Arduino

Non-intrusive load monitoring of domestic appliances has received steady interest in the last twenty years, first because of interest from energy companies interested in usage statistics for power balancing and, more recently, in order to assist users in tuning their habits for reduced power consumption. This has increased the need for accurate and economic methods of power measurement that can be efficiently implemented on cheap and easy-to-install platforms. To this end, we present a cheap and efficient device based on Arduino to monitor the usage of domestic appliances in real-time: Enerduino-pro. The design uses low-cost easy-to-assemble open-source electronic components and consists of four main parts: an Arduino UNO microcontroller, one photoresistor to measure instantaneous power absorption plus one optional additional one to measure reactive power, a WiFi shield, and an LED (for debugging purposes only). We describe the device, complete with open software and hardware specifications, and different use cases with proof-of-concept solutions.