Large Power Sources Research Articles

Proposal and design a comprehensive framework to provide water and energy from rain and precipitation

In this paper a new renewable energy source was proposed based on rain power. Rain energy was not used as an energy source up to now; so, in this research its applicability was investigated as a green large scale power source. Hence, three innovative mechanisms were presented to harvest the energy of rain. Firstly, the kinetic energy of rain drops was converted to electricity using piezoelectric harvesters designed and named as Pizo-panel collectors. Secondly, potential energy of collected rainwater was enhanced by utilizing designed towers and converted to electricity using a water turbine. Thirdly, collected water was used in osmotic power units to generate electricity from the salinity gradient of that rain water and brine. The results show that generated power in the presented power plant named as rain power plant, was considerable and can be used for diversifying of energy basket. In addition to power generation, collected water in the rain power plant can be used for supplying urban and agricultural need for water. The presented power source not only does not have destructive impacts on the environment, but also helps the soil to prevent it from splash and crusting erosion. The results showed that total global annual rain energy potential amount was estimated to be 3.44×108 GWh which is comparable with global potential of solar energy. Also, the results showed that for rainy areas with an annual rainfall of 200 cm, 2.59 kWh/m2 could be produced, which is equal to 51.7 MWh for an area of 200,000 m2.

Ground Fault in Medium-Voltage Power Networks with an Isolated Neutral Point: Spectral and Wavelet Analysis of Selected Cases in an Example Industrial Network Modeled in the ATP-EMTP Package

The paper presents some case spectral analysis of zero-sequence voltages and currents in an example industrial power distribution network. The network layout is based on typical power delivery networks in underground coal mines. Ground fault simulations have been made using an ATP/EMTP program. Due to the high environmental risks, the reliability of the protection relay operation related to their selectivity plays an important role. This paper tries to find the reasons for nonselective operation and unnecessary tripping in extensive mine cable networks, particularly with large power sources of higher-order harmonics. It was found that in transient states—due to the decaying oscillations occurring in complex RLC circuits—the results of short time measurements of the criterion values for ground fault protective relays can be overestimated (particularly for small values of ground resistance) and lead to nonselective tripping of a healthy cable line. Therefore, it might be advisable to increase the integration time used for measuring rms values. Also, if there is a significant level of higher harmonics in the industrial network generated by high-power converters, it should be noted that the higher harmonics of the ground fault current and currents measured by ground fault protection relays assume much higher values, which may also cause nonselective tripping. In this case, it may be advisable to use higher harmonic filters in the measuring circuits and to select a sufficiently high sampling frequency in the digital protective relays.

Application analysis of digital twin technology in power system

In the construction and development of modern society, in order to achieve the goal of double carbon, energy and power should build a digital, intelligent and electrified energy and power system in the transformation and development. According to the current statistical data analysis of China's energy Bureau, in recent years, more and more installed capacity of new energy generation in China, has become the world's second largest power source, while the proportion of non-fossil energy generation is also gradually rising, some scholars predict that in 2050, China's non-fossil energy will account for more than 50%. After understanding the concept of digital twin application technology, this paper mainly studies the application content and main direction of digital twin technology in power system according to the operation status of power system in the new era and the challenges faced by energy development, and then defines the development prospect of digital twin technology application in power system in the future.

Functional electrolyte: Design of anti-corrosion additives for Al collectors in LiFSI-based electrolyte

Recent lithium-ion rechargeable batteries (LIBs) are used as large power sources for EVs, etc. Compared to a single cell used in a cellphone, an EV batteries become higher voltage and higher capacity, therefore battery safety became an important issue. To improve the safety of battery, we are focused on increase the flash point of electrolyte. Since the flash point of current electrolytes for EVs is around room temperature, we are working on the development of high-safety electrolytes using solvents with flash points above 100 °C. In this work we used ethylene carbonate (EC) and γ-butyrolactone (GBL) as a high flash point solvent and thermally stable lithium bis(fluorosulfonyl)imide (LiFSI) was used as a Li salt. Since LiFSI corrodes Al current collectors, we report the results of adding a corrosion inhibitor to this high-safety electrolyte.

Conformally Large-Area Single-Crystal Piezocomposites with High Performance for Acoustic Transducers.

Large-area and conformal piezoelectric elements are highly desired for acoustic transducers to possess a large power source level and wide detecting range. To date, single-crystal piezocomposites attract much attention on enhancing the power source level and bandwidth for next-generation acoustic transducers, owing to their higher piezoelectric and electromechanical coupling properties compared to traditional piezocomposites. Unfortunately, it is still challenging to achieve large-area and conformal single-crystal piezocomposites because of the fragile nature, large anisotropy, and the limited grown size of piezoelectric single crystals. Here, we successfully fabricate the conformally large-area single-crystal piezocomposite with an area of 160 × 50 mm2 and a bending angle of 162° by a modified 3D-printing-assisted inserting method. The single-crystal piezocomposite exhibits a high thickness electromechanical coupling factor kt of 85% and a large piezoelectric coefficient d33 of 1150 pC/N, surpassing those of the reported large-area piezocomposites. The influence of the volume fraction and curvature radius of single-crystal PCs and acoustic transducers was investigated. Furthermore, we designed an acoustic transducer based on the conformal single-crystal piezocomposite. Benefiting from the excellent piezoelectric and electromechanical properties of the single-crystal piezocomposite, the transducer indicates a high maximum transmitting voltage response of 171.8 dB. Especially, its bandwidth (-3 dB) achieves 60 kHz with a resonant frequency of 292 kHz, which is about 1.8 times superior to the conformal acoustic transducer based on the ceramic piezocomposite with a similar resonant frequency. This work may benefit the future design and fabrication of high-performance and complex-shape piezoelectric composites as key materials for next-generation transducers.

Unified AC Transmission Expansion Planning Formulation incorporating VSC-MTDC, FACTS devices, and Reactive Power compensation

The main aim of the static Transmission Network Expansion Planning (TNEP) is to determine which and where new transmission equipment must be installed. The complexity added by the non-linearities leads to simplifications, which include the DC model. However, most non-linearities are solvable nowadays. Thus, the new scenario of large non-dispatchable power sources penetration and the several developments in technologies, e.g, Flexible AC Transmission Systems (FACTS) devices and High Voltage Direct Current (HVDC) interconnections, motivate the use of the AC model with its non-linearities. Some research works address the use of some of those technologies for TNEP in an independent fashion, which can lead to sub-optimal solutions. In this work, Voltage Source Controlled-Multiterminal HVDC (VSC-MTDC) systems, FACTS devices, and Reactive Power Planning (RPP) are integrated into the same planning optimization process, so that a unified AC TNEP formulation is proposed. A non-linear mathematical programming technique and a differential evolution based metaheuristics are chosen to achieve an optimal transmission configuration. To evaluate the benefits of the proposed approach, two IEEE modified test systems (9 and 118 buses) are used. Results suggest that more economical solutions can be obtained if different types of reinforcement strategies are taken into account in a unified approach.

Ultrafast response of self-powered humidity sensor of flexible graphene oxide film

Next-generation humidity sensor, as one of the smart devices in artificial skin or flexible electronics, will need to be self-powered, flexible, fast and accurately detecting in the microenvironment. Although various flexible humidity sensors have already been demonstrated, most of them rely on large external power sources to operate, and still suffer from slow response, poor selectivity in environmental stimuli, and expensive and complicated procedures. Here, we realize a self-powered humidity sensor with ultrafast response and recovery time of less than 0.3 s by flexible GO film. Importantly, of all state-of-the-art humidity sensors, this is the fastest response for humidity sensor. Moreover, the sensor has a high sensitivity within a wide range of RH from 33% to 98%, and an excellent selective response to humidity under multiple environmental stimuli, due to its moist-induced generator. Theoretical computations reveal that protons generated spontaneously from oxygen-containing groups and water molecules, have a fast diffusion behavior as Grotthuss hopping. In particular, we build four real-time measurement systems capable of respiration monitoring of human, smart leaf surface humidity sensor, and energy harvesting. Our work provides a simple way to fabricate next-generation self-powered sensor using GO film with outstanding humidity sensor performance.

Improved performance of stretchable piezoelectric energy harvester based on stress rearrangement

With the development of wearable devices and soft electronics, the demand for stretchable piezoelectric energy harvesters (SPEHs) has increased. Energy harvesting can provide energy when large batteries or power sources cannot be employed, and stretchability provides a user-friendly experience. However, the performance of SPEHs remains low, which limits their application. In this study, a wearable SPEH is developed by adopting a kirigami structure on a polyvinylidene fluoride film. The performance of the SPEH is improved by rearranging the stress distribution throughout the film. This is conducted using two approaches: topological depolarization, which eliminates the opposite charge generation by thermal treatment, and optimization of the neutral axis, which maximizes the stress applied at the surface of the piezoelectric film. The SPEH performance is experimentally measured and compared with that of existing SPEHs. Using these two approaches, the stress was rearranged in both the x–y plane and z-direction, and the output voltage increased by 21.57% compared with that of the original film with the same stretching motion. The generated energy harvester was successfully applied to smart transmittance-changing contact lenses.

An enhanced hypotrochoid spiral optimization algorithm based intertwined optimal sizing and control strategy of a hybrid electric air-ground vehicle

Hybrid electric air-ground vehicles (HEAGVs) are deemed as promising transportations due to their great versatility, mobility, and environmental values. Capable of ground-driving, vertical-take-off-and-land, and near-ground flight, HEAGVs are competent to pass poor road conditions such as broken bridges or cliffs. As a crucial part of the HEAGV development, size of the power sources is hard to design owing to different characteristics of air-driving and ground-driving. Large power sources would result in increased fuel consumption and accelerating battery degradation, while small ones might lead to insufficient power supply. Thus, optimal sizing of the power sources is needed at the functional level of a HEAGV design. Moreover, at the performance level, the control strategy should be taken into account simultaneously, which significantly affects the sizing process. However, the intertwined optimal sizing and control strategy of HEAGV becomes difficult to address due to the expanded design space. Motivated by this, an efficient co-optimization strategy is presented for the studied HEAGV, intended to simultaneously find optimal sizing of the battery pack and turbine-generator pack and optimal logic threshold control parameters. The initial mass, fuel consumption, and battery degradation are chosen as optimization objectives to formulate an objective function. Then, a novel enhanced hypotrochoid spiral optimization algorithm (EHSOA) is proposed to address the intricated co-optimization problem. In this algorithm, an enhanced bi-considering mechanism is firstly proposed to avoid the optimization process being trapped in local optima. The co-optimization is implemented under an air-ground driving cycle. Results show that, compared to the initial design, the proposed strategy reduces initial mass, fuel consumption, and battery degradation by 5.08%, 26.10%, and 2.08%, respectively. Finally, the proposed EHSOA is demonstrated to be more qualified to solve the intricated co-optimization problem in comparison to other optimization algorithms. The proposed co-optimization strategy might provide theoretical insights for future HEAGV powertrain designs.

MATLAB Implementation of an HTS Transformer-Rectifier Flux Pump Using HTS Dynamic Voltage Switches

Thispaper proposes a novel approach to the modelling of HTS transformer-rectifier flux pumps that can charge HTS magnetic loads without the need for bulky current leads or expensive cryogenic requirements. The model was built in MATLAB/Simulink for a flux pump with 2 HTS switches, an HTS transformer with a primary inductance of 15 mH, secondary inductance of 50 µH and an HTS magnetic load with an inductance of 2 mH. With a 5 A pk-pk triangular current waveform at 2 Hz the system can load the HTS load to 34.63 A in 5 s. This incremental addition of flux to the load demonstrates the advantage of flux pumps as they can charge high-field magnets without the need for large power sources. The speed of flux pumping is improved by increasing the system frequency, the magnitude of the dynamic voltage developed in the HTS switches and by increasing the primary inductance of the transformer. This has widespread industrial applicability in fields such as the charging of high-field magnets for MRI systems.

Alternating pressure control system for hydraulic robots

Hydraulics is a promising technology for robots. However, traditional hydraulic infrastructures are often large and power-inefficient, with large power sources that hinder mobility. In contrast, electro-hydrostatic actuators are relatively power efficient, but their cost and weight can be excessive in systems with a higher number of degrees of freedom. In this paper, we propose a new alternating pressure control system for hydraulic systems with a higher number of degrees of freedom based on an alternating pressure source system. In this system, the valves open and close in synchronization with a pump with sensor feedback, allowing either pressure or position in each actuator to be controlled independently. With the proposed system, a centralized pump can be used with simplified tubing and simple on–off valves. Moreover, we developed a dynamic duty ratio system that improves performance and reduces pump utilization time. The experimental results confirmed that both the position and pressure of each actuator can be controlled in parallel on a multi-degree-of-freedom system.

S-Band GW-Level Relativistic Magnetron Operating at Relatively Low Applied Voltage

To realize miniaturization of high-power microwave (HPM) systems, a high-efficiency GW-level relativistic magnetron (RM) operating at a relatively low applied voltage is presented, which does not require a large high-energy pulsed power source. An eight-cavity anode block with rectangular vanes is adopted. The resonators in the anode block, where the high-frequency energy is directly stored, are enlarged by introducing rectangular vanes. The microwave extraction is accomplished by a step-like diffraction output, which benefits the compact magnet system design. In experiments, several transparent cathodes have been employed to investigate the cathode effects on the magnetron performance, including cathode configurations, cathode endcaps, and emission length. With the optimal cathode, the proposed RM can radiate microwave power of 1.1 GW with a power conversion efficiency of 51% at 2.72 GHz when the applied voltage is around 380 kV and the axial magnetic field is 0.44 T.

Force tracking model and experimental verification on a novel magnetorheological damper with combined compensator for stay cables of bridge

As one of the most promising semi-active control devices, magnetorheological (MR) damper has received significant attention in the past few decades because it can offer the adaptability of active control devices in the absence of the associated large power sources. In this study, a new single-rod MR damper with combine volume compensator are proposed, and the design method of combined compensator with independent functions of volume compensation and compensation force is proposed. Then the dynamic tests of the single-rod MR damper are carried out to demonstrate its working performance. The identified sigmoid model is adopted as forward model to characterize the performance of the MR damper. And the force tracking method is put forward by performing inverse of the forward model. Finally, the force tracking simulation of the optimal LQR control force for the stay cable is given to show its feasibility.

Metamorphosis in Insect Muscle: Insights for Engineering Muscle-Based Actuators.

One of the major limitations to advancing the development of soft robots is the absence of lightweight, effective soft actuators. While synthetic systems, such as pneumatics and shape memory alloys, have created important breakthroughs in soft actuation, they typically rely on large external power sources and some rigid components. Muscles provide an ideal actuator for soft constructs, as they are lightweight, deformable, biodegradable, silent, and powered by energy-dense hydrocarbons such as glucose. Vertebrate cell lines and embryonic cultures have allowed critical foundational work to this end, but progress there is limited by the difficulty of identifying individual pathways in embryonic development, and the divergence of immortal cell lines from these normal developmental programs. An alternative to culturing muscles from embryonic cells is to exploit the advantages of species with metamorphic stages. In these animals, muscles develop from a predefined pool of myoblasts with well-characterized contacts to other tissues. In addition, the endocrine triggers for development into adult muscles are often known and tractable for experimental manipulation. This is particularly true for metamorphic muscle development in holometabolous insects, which provide exciting new avenues for tissue engineering. Using insect tissues for actuator development confers additional benefits; insect muscles are more robust to varying pH, temperature, and oxygenation than are vertebrate cells. Given that biohybrid robots are likely to be used in ambient conditions and changing environments, this sort of hardiness is likely to be required for practical use. In this study, we summarize key processes and signals in metamorphic muscle development, drawing attention to those pathways that offer entry points for manipulation. By focusing on lessons learned from in vivo insect development, we propose that future culture designs will be able to use more systematic, hypothesis-driven approaches to optimizing engineered muscle. Impact statement This review summarizes our current understanding of metamorphic muscle development in insects. It provides a framework for engineering muscle-based actuators that can be used in robotic applications in a wide range of ambient conditions. The focus is on identifying key processes that might be manipulated to solve current challenges in controlling tissue development such as myoblast proliferation, myotube formation and fusion, cytoskeletal alignment, myotendinous attachment and full differentiation. An important goal is to gather findings that cross disciplinary boundaries and to promote the development of better bioactuators for nonclinical applications.

Effect of modified bouc-wen model parameters on the dynamic hysteresis of magnetorheological dampers

Magnetorheological (MR) dampers are a semi active control device that becoming a promising actuators in vibration mitigation. The unique properties of MR fluids are used to control the damping force without consuming large power source. Despite MR dampers are fail-safe, efficient, and robustness devices, they poses significant nonlinear characteristics. A well-known Bouc-Wen models and their extension modified Bouc-Wen are the most accurate models that predict the hysteresis of the MR dampers. However, these models suffer from some complexity and limitations and they miss a good fitting to the measured data. In this paper, the existing modified Bouc-Wen (MBW) models are introduced and their dynamic characteristics are simulated using MATLAB Simulink environment. The robustness of the model is judged by a comparison between the experimental tests of the MR damper (on and off state) on the MTS damper test machine in MTC and the simulated characteristics. To better understand the damper nonlinearity, an investigation into the effect of the model parameters on the dynamic characteristics of the damper is studied. A parametric study is proposed to identify the optimal model parameters that best fits the experimental data. The response of the model with the obtained parameters is validated across the measured MR damper characteristics under different sinusoidal excitations and command current. The results show a good agreement between the simulated and measured responses of the MR damper.

High Temperature Superconducting (HTS) Cable Application to Ship Deperming Work

We study a system of high electric current cable laid on the seabed for purpose of naval ship magnetic deperming. Moderate magnetic field over 2400 A/m is to be imposed on the volume equivalent of several thousand tons of ship, with alternately changing direction and gradually decreasing intensity. Cable with conventional conductor needs large power source because of the requirements coming from the cable’s resistivity and high decay of magnetic field depending on distance from source. High Temperature Superconducting cable is suitable for this application. We set a requirement of maximum current of the cable as 200 kA and the length as 1200 m set on seabed of 12 m depth. Our recent design of the cable composed of Rare-earth-Barium-Copper-Oxide tape conductor stack, bundled and cooled by helium gas to 50 K. As a next step, cooling to 20 K with the same base concept of cable is shown to mitigate high expense of the tape conductor.

(Invited) Controlling the Ordering of Na+ and Vacancy By Ti-Doping in P2-Na0.67Co1-XTixO2 for High Energy and Power Density Cathode Materials in Sodium-Ion Batteries

Sodium-ion batteries (NIBs) for large power sources having kWh or MWh scale of energy are highly interesting alternatives for lithium-ion batteries because of abundant sodium resources in the earth and high chemical similarity between Li and Na ions. However, due to the high atomic weight of Na+ and the low working potential of NIBs, the energy and power densities of NIBs are also required to be improved for wide applications. Despite the similar chemical behavior of Na ions in the rechargeable batteries, the high performance of the active material in NIBs is an essential research- topic for the realization of NIBs. Especially, Na ion having a larger diameter than Li-ion in the P2 type layered structure has a distinct Na+/vacancy ordering behavior presenting multiple voltage plateaus during sodium ion insertion and extraction in the electrochemical cycling. This different behavior from lithium-ion batteries makes the sodium ion diffusion complex in the solid matrix due to the pass-through of various stable Na+/vacancy arrangements. This presentation covers an improvement in the electrochemical performance of the cathode material, Na0.67Co1-xTixO2 having P2 type crystalline structure by using various amounts of Ti doping to control Na/vacancy ordering for mitigating the Na ion diffusion in the solid matrix as well as for extending the de-sodiation range to 4.4 & 4.5 V vs. Na/Na+. The proposed material having Ti doping presents a highly relieved an electrochemical Na+/vacancy ordering behavior from the that of Na0.67Co1-xO2 having a severe capacity loss at high potential because of irreversible phase transitions. In particular, 10 % Ti-doping in the Co content highly advances the cycleability by showing 115 mAh g-1 at the 100th cycle, as well as the rate capability by reaching 108 mAh g-1 at a current density of 1000 mA g-1. The detail diffusion kinetics and phase behaviors from the prepared materials are investigated by a systematic analysis combination comprising TEM, in-situ XRD, and electrochemical methods.

Peak Shaving Model for Coordinated Hydro-Wind-Solar System Serving Local and Multiple Receiving Power Grids via HVDC Transmission Lines

To meet the rapid growth of electricity demand and reduce carbon intensity, China is developing renewable energies rapidly including hydropower, wind and solar power. Due to the geographical mismatch of energy sources and demands in China, many long-distance and large-scale UHVDC and HVDC transmission projects have been built to transmit electric power from the western renewable bases to eastern coastal load centers. Some provincial power sources serve both local demands and deliver power to multiple regional power grids via HVDC transmission lines. As large capacity HVDC power transmission projects have great impacts on receiving-end power grids. Thus, the local exporting power grid should consider both local demands and energy importing area demands. A mixed-integer linear programming day-ahead peak shaving model to minimize the peak-valley difference in residual load after renewable generation of multiple power grids is developed. The model uses chance constraints to compensate for forecast errors of wind and solar power with hydropower, and introduces maximum daily power regulation times and stair-like power curve constraints of HVDC tie lines to avoid frequent HVDC power change and ensure power grid safety. The case studies in Yunnan province, which has large scale hydro, wind and solar power sources and delivers power to multiple regional power grids via HVDC transmission lines, shows the proposed model can shave peaks from multiple power grids effectively, hydropower can compensate for wind and solar forecast error and obtain satisfying results for multiple power grids, and that HVDC constraints can avoid their frequent power change and ensure the power grid safety.

Damping electromechanical oscillations using supplementary controls at VSC-HVDC stations based on reduced low order models

The interconnection of remote large power systems, and the connection of large non-synchronous renewable power sources to AC power systems have found solutions by means of transmission in high voltage direct current (HVDC) using technology based on voltage source converters (VSC). This technology has the advantage of fast response the possibility of providing reactive power to AC systems, and the use of supplementary control signals to their automatic voltage regulators to improve stability AC systems. This paper proposes the computation of robust supplementary controller type H∞ based on low-order models of the power system, obtained by application of N4Sid identification technique, to be installed at the VSC converter stations of a HVDC link to dampen electromechanical weak modes. The proposed model shows that using simulated input/output data by means of typical software available at utilities is possible and useful. The methodology includes the modeling of uncertainties due to the different operational points where the power system can be placed by load variations and generation dispatch. This paper also presents a methodology for the computation of robust supplementary control at VSC-HVDC stations that guarantee robustness in a wide range of operating conditions and even better to improve the damping of electromechanical oscillations. It is also proposed a methodology for defining the weighted functions based on the uncertainties theory. Likewise, it is validated with the simulation of a critical contingency in a weakly damped system obtaining an improvement in damping of electromechanical oscillations. The robust supplementary control is compared to the performance of the classical POD.

WiFi-based through-the-wall presence detection of stationary and moving humans analyzing the doppler spectrum

Through-the-wall (TTW) sensing is relevant in several scenarios. In particular, a system able to detect the presence of a noncollaborative person behind a wall could be used by law enforcement for better planning actions in case of standoffs and hostage situations. For emergency situations, first responders could use such a system to detect the presence of people through rubble and collapsed structures. Traditionally, these types of systems have been designed using a radar approach. In particular, ultrawideband systems (2 GHz of bandwidth) have been proposed for detecting human presence by using radio frequency (RF) signals [1], [2]. These systems usually require a large power source and big antennas. Recently, to reduce the power and complexity of these devices, the use of opportunity signals, such as WiFi signals, has been considered [3]–[6].