Light Load Research Articles

Обоснование патогенетической направленности поэтапной световой иммобилизации в макулярной и витреоретинальной хирургии

Purpose. To substantiate the pathogenetic orientation of staged light immobilization in macular and vitreoretinal surgery. Material and methods. Literature data and own longterm clinical observations of the results of vitreoretinal, optoreconstructive, microsurgical and laser therapeutic, optical and refractive operations were analyzed. Particular emphasis was placed on the results of photostress-testing and differential aberrometry in macular and vitreoretinal pathology in combination with ametropia (150 eyes, 96 patients). Results. Studies have shown that changes in the retina and surgical operations for macular and vitreoretinal pathology create conditions, when the usual physiological light load begins to have a damaging effect on the retina and aggravate the course of the disease. The latter indicates the expediency of using various techniques for limiting the light load on the retina. This requires a gradual smooth transition from complete to various options for partial light immobilization. In all cases, optical photoprotection from external UV radiation, complete correction of ametropia and associated optical aberrations were shown This was indicated by a positive correlation between defocus and higher-order aberrations with an increase in visual acuity recovery time after a photostress-test. The timing of such immobilization should take into account the severity of the pathological process and the specific type of surgical intervention. This can be realized with a large arsenal of spectacle, contact, intraocular photochromic and spectral lenses that block the violet rays of visible light and attenuate the flow of rays of the blue spectral range. If full optical correction of ametropia, induced irregular astigmatism and higher order aberrations is impossible, their personalized laser correction is shown according to keratotopography and aberrometry data. This is indicated by the revealed positive correlation between the recovery time of visual acuity after the photostress-test, defocus, and higher-order aberrations. Conclusion. Gradual light immobilization in macular and vitreo-retinal surgery has a pathogenetic focus and should be more widely used in ophthalmic practice. Keywords: light immobilization, deprivation, photoprotection, macular and vitreo-retinal surgery

Efficiency optimization for LCC‐LC compensated inductive coupling power transfer system with load‐independent zero‐phase‐angle and constant voltage output

SummaryHigh‐order compensation for the inductive coupling power transfer (ICPT) system is preferred due to its high design freedom and excellent coil current harmonics suppression capability. Especially, the good harmonics suppression capability is helpful to implement the synchronous wireless transfer of energy and data with a pair of data communication coils integrated into the energy transfer coils. Thus, on basis of THD1 and THD2 comparison for different high‐order compensation topologies, the LCC‐LC compensated ICPT system with load‐independent zero phase angle (ZPA) and constant voltage output is discussed in this paper. Compared with other high‐order compensation topologies with constant voltage output such as LC‐LC, LC‐LCC, and LCC‐LCC, the LCC‐LC has the advantages of ZPA operation with zero voltage switching and less secondary‐side components. For a given magnetic coupler, infinite feasible combinations of compensation parameters can make the system accomplish ZPA and the same output characteristics. Thus, efficiency optimization of the LCC‐LC compensated ICPT system can be investigated by configuring the optimal compensation parameters. To validate the theoretical analysis, especially the efficiency improvement, the experimental platform with 270 V input and 270 V/3 kW output is designed and built. The comparative experimental results for three different the compensation parameters show the optimized system can improve greatly conversion efficiency over the entire load range, especially under light load.

Dynamic Service Mechanism of Double-Row Spherical Roller Bearings Due to Self-Aligning Behavior

Spherical roller bearings (SRBs) are widely used under self-aligning operating conditions, such as rotor bending or an angular misalignment between inner and outer rings due to their self-aligning function. However, the characterization of SRBs’ self-aligning function is often ignored in the present models. The reason for this is that the self-aligning condition is essentially a fault condition, and many scholars have assumed SRBs are in an ideal operating condition. Although there is nothing wrong with this analysis theoretically, it is incapable of characterizing SRBs’ service behavior comprehensively. In this work, the Lagrange equation was introduced to model the relationship among the rollers and the inner and outer rings. The contact region in particular was characterized in detail in order to solve the problems of undetermined contact status (UCS) and the varying law of the self-aligning contact angle (SAC angle). For the experiment, a novel SRBs pedestal with a self-aligning operating condition was designed, and the relevant self-aligning function testing was carried out. A good agreement was shown between the theoretical and experimental results. The results pointed out that, if taking no account of the self-aligning function, SRBs can be regarded as angular contact ball bearings or cylinder roller bearings. The amplitude of the inner-ring motion orbit is determined by the external load, but the shape is influenced by the direction and magnitude of the SAC angle. In the example of this paper, the values of the main frequency equal 136.8 Hz. Some additional frequencies are clearly aroused under the self-aligning operating condition, whose value is approximately equal to 8.3 Hz or its integer multiples. The dynamic performance of SRBs will be substantially improved by a light axial load plus an anticlockwise self-aligning contact angle rather than a large axial preload.

Engineering Geological Properties of Subsurface Soils for Foundation Purposes in Parts of Bayelsa State, Niger Delta

The geotechnical properties of soil samples obtained from eight (8) boreholes from some parts of Bayelsa State were determined to assess their suitability as foundation materials. The geotechnical characteristics of the soils were determined from the laboratory and field works. The Atterberg limit results reveal that the liquid limit ranges from 46.5% to 98.3%, the plastic limit ranges from 23.5% to 56.3% while the plasticity Index values range from 17.1% to 51.3%. The clays are highly plastic (CH) in the USCS designation. The natural moisture content ranges from 35.9% to 91.3%, the moisture content is relatively high, this could be attributed to the wet season period of sampling. The particle size analysis disclosed that the cohesionless samples are predominantly fine to medium and medium dense sands. The triaxial test results shows that values of Cohesion (C) ranges between 16 – 40KN/m2 and the friction angle (ϕ) ranges between 3 – 6o. The result of the undrained shear strength of the clay ranges between 20Kpa and 24Kpa. The coefficient of consolidation (Cv) of the clay soil samples varies between 1.13 m2/yr and 2.89 m2/yr, the coefficient of volume compressibility, (Mv) for these same materials varies between 0.215 m2/MN and 6.338 m2/MN. Generally, indicating clay layers of high to very high compressibility. The calculated values for ultimate bearing capacity (qu) and allowable bearing capacity (qa) varies between 100.29KN/m2 to 151.49 KN/m2 and 33.42 KN/m2 to 50.50 KN/m2 respectively. The analyses showed that the values of ultimate bearing capacity increases with depth. The calculated settlement ranges between 69mm to 653mm with the thickness of clay of 7.5m and 30.0m respectively. Raft foundation is best suited for these weak, soft foundation materials for light structural loads but for heavy structural load, a pile foundation is recommended.

A Modulation Method for Three-Phase Dual-Active-Bridge Converters in Battery Charging Applications

The Three-phase Dual-Active-Bridge (DAB3) converters are a common choice for quick charging stations for batteries in electric vehicles due to their high power density, versatility, and galvanic isolation capability. However, the DAB3 topology has limited soft-switching range, particularly under light load conditions when the voltage conversion ratio differs significantly from unity, resulting in hard switching, increased loss, and higher electromagnetic interference. To address these issues, various techniques have been proposed, but they often lead to other problems such as higher current ripple or unbalanced thermal distribution. In this paper, a new modulation scheme, called symmetric duty-cycle control (SDM), is proposed for DAB3 converters to overcome these issues. A multiaspect comparison of SDM was conducted against two existing techniques, SPS and ADCC, and its superiority was validated through simulation and experimental results. Our proposed SDM scheme provides a current ripple within 10% to 15% of the average current and enables zero current switching for the whole voltage and power ranges. Additionally, a modified version of SDM can even improve overall efficiency by 7% compared to the conventional SPS technique.

Should We Use the Men Load–Velocity Profile for Women in Deadlift and Hip Thrust?

Injuries are common in team sports and can impact both team and individual performance. In particular, hamstring strain injuries are some of the most common injuries. Furthermore, hamstring injury ratios, in number of injuries and total absence days, have doubled in the last 21 seasons in professional soccer. Weakness in hip extensor strength has been identified as a risk factor in elite-level sprinters. In addition, strength imbalances of the hamstring muscle group seem to be a common cause of hamstring strain injuries. In this regard, velocity-based training has been proposed to analyze deficits in the force-velocity profile. Previous studies have shown differences between men and women, since there are biomechanical and neuromuscular differences in the lower limbs between sexes. Therefore, the aim of this study was to compare the load-velocity profile between males and females during two of the most important hip extension exercises: the hip thrust and the deadlift. Sixteen men and sixteen women were measured in an incremental loading test following standard procedures for the hip thrust and deadlift exercises. Pearson's correlation (r) was used to measure the strength of the correlation between movement velocity and load (%1RM). The differences in the load-velocity relationship between the men and the women were assessed using a 2 (sex) × 15 (load) repeated-measures ANOVA. The main findings revealed that: (I) the load-velocity relationship was always strong and linear in both exercises (R2 range: 0.88-0.94), (II) men showed higher velocities for light loads (30-50%1RM; effect size: 0.9-0.96) than women for the deadlift, but no significant differences were found for the hip thrust. Based on the results of this study, the load-velocity equations seem to be sex-specific. Therefore, we suggest that using sex-specific equations to analyze deficits in the force-velocity profile would be more effective to control intensity in the deadlift exercise.

Improving Work Attitudes And Assistive Devices Can Reduce Subjective Complaints And Increase The Productivity Of Weavers

Gringsing weaving products is a part of handicraft or home industry. They are still confessed at present and produced by simple technology with hand in hand. This activity as a business of income from the most of women in Tenganan Pegringsingan Village of Manggis Sub District, Karangasem Regency. A work attitude with no planned well and they do not use a tool instruments for helping then working correctly, it is caused a subjective complaints of the workers so the production is not maximally and will cause the productivity of the workers come down. Woven products workers is required a carefulness and neatness of the workers, with long sitting posture on the flour covered by something material. It is not aware of this problem in to the anatomy and physiology of the workers and they will have a lot of complaint, sick, or pain on their next, hand, low back, anus, thigh, eyes. It is caused static work load frequently, so that they will be to come a decrease activity and low motivations, it’is activity and the work is not done efficient and effective. The variable that is measured in this study is decrease workload, subjective complaint, work efficiency (long work), and work productivity. The research has been studied to the sixteen weaving workers that were chosen without rules with treatment by subject program with cross over design, its analyses unit considering group variance. It has been intervened by work attitude with supporting tool for instant ‘peliper, tingklik, por (supported by sponge), barble, and using eyes glasses and group workers. This study is analyzed by t-paired, and there is a significant work load reduction (p<0.005), which is the pulse of the workers come down from 89,62 beats per minutes to be 82,56 beats per minutes (±5,60) in the same of the light work load category. The subjective complaints of the work load come down showed significant value (p<0.005) that is from Nordic Body Map score 56,92 (16.14) to be 28.86 (7.32). By the efficient work 7 hours a day with support tools, it is to be come the productivity increase (0,34%) and work productivity (7,9%) significantly (p<0.005).

A Novel Bio-Inspired Energy Optimization for Two-Tier Wireless Communication Networks: A Grasshopper Optimization Algorithm (GOA)-Based Approach

Energy consumption has become one of the most challenging problems in future wireless communication networks. One of the promising methods in fifth generation (5G) cellular networks to meet the ever-increasing demand for high data traffic is wireless heterogeneous networks (HetNets). Adding more base stations may improve network coverage, but leads to the consumption of a significant amount of power. The scheme of two-tier networks contains small cell base stations (SCBs) that cooperate with macro cell base stations (MCBs) to provide wider coverage. Some small cell base station SCBs are experiencing light traffic loads due to the movement of user equipment (UEs), but these SCBs still consume a considerable amount of energy. Therefore, to reduce SCBs’ power consumption and maximize the overall energy efficiency (EE) of a two-tier network, some SCBs need to be switched off. In this paper, we extend the operation modes for BSs and present a novel mechanism to select an appropriate operation mode for each SCB that is based on bio-inspired behavior. We employ a bias function to manage the power consumption of each operation mode. Each SCB has four power mode selections: On, Standby, Sleep, and Off. We formulate the EE maximization problem under a set of constraints and present a Grasshopper Optimization Algorithm-based Variant Power Mode Selection (GOA-VPMS) to solve it. The proposed algorithm scheme outperforms previous work and provides a higher EE, according to the simulation results.

A Novel Phase-Shift Pulsewidth Modulation Method for Light-Load Bidirectional Resonant Converter

For the bidirectional full-bridge <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLLC</i> resonant converter, soft switching of primary side and secondary side switches and bidirectional power transmission are its obvious advantages. However, in the pulse frequency modulation control under light-load conditions, the converter will have the disadvantages of output voltage imbalance and low transmission efficiency. In order to improve the range of voltage regulation and efficiency of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLLC</i> resonant converter under light-load conditions, a novel phase-shift pulsewidth modulation method is proposed in this article. There is low voltage gain regulation and low operation losses can be achieved under light load. Considering the parasitic parameters and dead time of the switches, the voltage gain of the proposed control method under light load is precise research by using the time domain analysis method. Finally, an experimental prototype of a bidirectional full-bridge <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLLC</i> resonant converter with 200 V input voltage, 200 V output voltage, and a rated power of 800 W is designed. According to the simulation and experimental results, it can be shown that the proposed control method is effective under light-load operation.

A Fast Transient Current-Mode Buck Converter With Linear Regulation Mode

This article proposes a configurable supply mechanism in the power stage to simultaneously improve the load transient response and power conversion efficiency. The power stage, comprising a dc–dc converter and an auxiliary power circuit (APC), can be organized depending on the variable load conditions. During step-load changes, the APC can provide an additional charging or discharging current to the output capacitance of the dc–dc converter to compensate for any differences between the load current and inductor current. Meanwhile, two auxiliary transient transistors are employed to immediately adjust the output level of the error amplifier because the peak current-mode control is used in the dc–dc converter. Thus, the recovery time and output transient ripple are enhanced significantly. At the steady state, the APC is inactivated; thus, the conversion efficiency of the dc–dc converter does not degenerate. Above medium loads, only the dc–dc converter is activated to deliver adequate power with high efficiency. At light loads, the APC acts as a linear regulator to take over the energy delivery scheme because power consumption is reduced effectively while the output voltage is kept. Therefore, the hybrid operation can guarantee improvements in load transient response and power conversion efficiency at light loads. The proposed converter was fabricated with 0.35- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m CMOS technology. The experimental results showed that the recovery times for 450-mA step-down and step-up loads are 1.6 and 2.0 μs, respectively. Comparing to when the transient mode is disabled, the recovery time of the output voltage is improved by over ten times when the transient mode is enabled. Further, the efficiency improvements with the proposed method at load current of 20 mA under the output voltages of 2.5 V and 1.8 V are 13.8% and 4.9%, respectively.

Performance Characterization of T-Type Multilevel Dual Active Bridge DC-DC Converter

Conventionally, single phase shift control technique is used for controlling dual active bridge (DAB) performance, which works efficiently at unity voltage conversion ratio and full load. However, when there is mismatch between primary voltage and reflected secondary voltage on primary side at light load, its efficiency reduces because of increased current stress and reactive power. Moreover, due to single control variable, its power flow controllability is confined. In this paper, analysis, implementation and performance characterization of isolated bi-directional T-type multilevel dual active bridge DC-DC converter topology is presented. It has five level voltages on both the primary and secondary side of high frequency transformer, which reduces the current stress and reactive power over wide operating range. It also has five control variables which gives extra edge for enhancing power flow controllability. Comparative analysis reveals that the proposed converter has high efficiency over wide operating range, due to reduced reactive power and current stress. Performance of the proposed T- type multilevel dual active bridge DC-DC converter topology has been verified via simulation and experimental prototype developed in the laboratory.

A New Soft-Switching AC–DC Converter Based on Coupled Inductors for Onboard Charging Applications

This article proposes a soft-switching full-bridge ac–dc converter consisting of its hard-switching counterpart and simple active auxiliary branch. The auxiliary branch is composed of an inductor and two power switches. The proposed converter features zero voltage switching (ZVS) turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> for main switches and zero current switching (ZCS) condition for auxiliary switches. The ZVS condition is created by turning on auxiliary switches ahead of the main switch turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> signal to reversely excite the auxiliary inductor. The two mutually coupled inductors connected in series in opposing magnetic field manner are designed as the main filter inductor and to provide positive voltage for the auxiliary inductor to degauss it as well. Meanwhile, the auxiliary inductor contributes ZCS turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> to the auxiliary switches because it slows down the change rate of the current through the switches. Considering the parasitic capacitors of the auxiliary switches inevitably resonate with the auxiliary inductor, a clamping technique is given to alleviate the additional voltage stresses caused by the resonance. Then, the mathematical parameter design is deduced to guide the converter realization. Finally, a laboratory prototype with 1000 W rated power operating at 50 kHz switching frequency is completed and tested to demonstrate the soft-switching features. The efficiency of the proposed converter is up to 97.67% at full load and the maximum efficiency improvement is 5.3% at light load, which further highlights the outstanding performance.

High Efficiency Bidirectional LLC+C Resonant Converter With Parallel Transformers for Solar-Charged Electric Vehicles

Recent interest in electric vehicles with onboard solar generation presents a new opportunity for using solar electric vehicles (SEVs) for distributed generation when the traction battery is fully charged. This concept presents a new power electronic challenge: the onboard charger should have high efficiency in the grid-to-vehicle (G2V) direction for normal charging power levels (i.e., 6.6 kW) and also high efficiency in the vehicle-to-grid (V2G) direction for much lower solar power levels (i.e., < 800 W). However, typical onboard charger topologies have low efficiency at light loads. This article proposes a novel bidirectional LLC+C converter to address this challenge. It operates as a full-bridge LLC converter in the G2V direction and a half-bridge LLCC converter with a smaller transformer in the V2G direction. Simulation results show a maximum efficiency gain of 5.1% in the V2G direction compared to the standard full-bridge LLC converter. To experimentally validate the topology and operation, a 6.6-kW prototype with 450–700-V input is designed, built, and tested. The experimental results show that the proposed converter achieves high efficiency in the V2G direction at 700 W (95.7%).

Fixed Switching Frequency Hybrid Modulation With ZVS for Single-Phase Inverter

Soft switching technology is an effective way to reduce the switching loss of the single-phase inverter to improve efficiency. Because of the ease of implementing soft switching, inverter works in boundary conduction mode (BCM) is widely used. On the contrary, BCM causes wide variation in switching frequency and large inductor current ripple. In this article, a fixed switching frequency hybrid modulation method for the inverter is proposed, which can achieve zero-voltage switching without changing the switching frequency and reduce the peak value of inductor current. The modulation achieves good tracking of the output current with different loads by switching mode between the triangular mode and the trapezoidal mode accurately. For implementing modulation, the operation states of the inverter with different conditions are analyzed in detail, the number of operation states is deduced and the state machine about mode switching is summarized. In addition, a single-phase inverter prototype is designed to verify the feasibility and effectiveness of the proposed modulation. Compared with BCM, the efficiency of the inverter at both light load and full load is increased.

Improved Grant-Free Access for URLLC via Multi-Tier-Driven Computing: Network-Load Learning, Prediction, and Resource Allocation

Grant-Free (GF) access has been recognized as a promising candidate for Ultra-Reliable and Low-Latency Communications (URLLC). However, even with GF access, URLLC still may not effectively gain high reliability and millimeter-level latency, simultaneously. This is because the network load is typically time-varying and not known to the base station (BS), and thus, the resource allocated for GF access cannot well adapt to variations of the network load, resulting in low resource utilization efficiency under light network load and leading to severe collisions under heavy network load. To tackle this problem, we propose a multi-tier-driven computing framework and the associated algorithms for URLLC to support users with different QoS requirements. Especially, we concentrate on <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K $ </tex-math></inline-formula> - repetition GF access in light of its simplicity and well-balanced performance for practical systems. In particular, our framework consists of three tiers of computation, namely network-load learning, network-load prediction, and adaptive resource allocation. In the first tier, the BS can learn the network-load information from the states (success, collision, and idle) of random-access resources in terms of resource blocks (RB) and time slots. In the second tier, the network-load variation is effectively predicted based on estimation results from the first tier. Finally, in the third tier, by deriving and weighing the failure probabilities of different groups of users, their QoS requirements, and the predicted network loads, the BS is able to dynamically allocate sufficient resources accommodating the varying network loads. Simulation results show that our proposed approach can estimate the network load more accurately compared with the baseline schemes. Moreover, with the assistance of network-load prediction, our adaptive resource allocation offers an effective way to enhance the QoS for different URLLC services, simultaneously.

A Faulty Submodule Mathematical Model-Based Localization Strategy for Switch Open-Circuit Fault of Module Multilevel Converter

A faulty submodule (SM) mathematical model-based switch open-circuit fault diagnosis and localization (FDL) method for module multilevel converter (MMC) is investigated in this article, which can diagnosis the faulty switch in time. Initially, the mathematical model is established through the modified switching function of the faulty SM, which can express the real switching state of the faulty SM accurately. Based on the proposed mathematical model, an innovative FDL method for MMC is proposed. The faulty switch is located by comparing the capacitor voltage calculated through the proposed mathematical model with the sampled capacitor voltage value. To enhance the accuracy and anti-interference ability of the model, the capacitance observation method is proposed in the capacitor precharge stage. The proposed FDL method can diagnose and locate faulty switch in any state of the SM, even if the operating state of the faulty SM is the same as that of the normal SM. Single or multiple switch open-circuit faults can be accurately located by this method under either light or heavy load conditions. Finally, the mathematical model and FDL method are verified through simulation and experiment.

A Phase-Shift Control Method of Triple-Active-Bridge Converter for Reducing Power Loss Under Light Load Condition

This paper presents a phase-shift control method of a triple-active-bridge converter for distributed power supply systems with multiple batteries. The experimental results show that the reactive power through the transformer can be suppressed under a wide range of conditions. The proposed phase-shift control method improves the light load loss at 500W by approximately 30% compared to the conventional method. In addition, according to the power-transmission characteristics of the proposed method, for applications in which a voltage source connected to an input port is attached and detached, the power supply and demand can be adjusted between each output port while gradually lowering the charge of the input port by utilizing the characteristics of the charging operation. Therefore, the converter can continue to operate regardless of the attachment and detachment of the input port-voltage source.

A Load Adaptive Hybrid DPS Control for DAB to Secure Minimum Current Stress and Full ZVS Operation Over Wide Load and Voltage Conversion Ratio

Wide variations in voltage conversion ratio and loading are the most important parameters to consider when designing off-board EV chargers to achieve high power density and efficiency. Dual phase shift (DPS) modulation provides a better way for dual active bridge (DAB) DC-DC converter operation when load side parameter variation is utmost important. To accomplish this, conventional DPS control is modified to ensure zero voltage switching (ZVS) across the entire load range despite wide variations in voltage conversion ratio. The designed control provides ZVS of all FETs as compared to the conventional DPS control over full loading range. For this, magnetizing inductance of HF isolation transformer is utilized and designed to shape the secondary side current for getting ZVS for both active legs. The light loading performance of the converter is improved with the bidirectional conduction angle control. The hybrid utilization of DPS control is incorporated with minimum peak current stress considerations. A Karush-Kuhn-Tucker (KKT) method based on Lagrange's multipliers is used for mathematical derivation of optimized solution of both control parameters. Performance of designed control is verified using experimental results for wide variation in battery terminal voltage. For validation, a 1250 W laboratory prototype is developed. A comparison of ZVS regions among the conventional and designed modulation technique, shows the effectiveness under wide voltage and loading scenarios.

A power system stability assessment framework using machine-learning

With the planned massive integration of renewable energy resources, the electric network is gradually becoming a less predictable system. In such power systems, the set of critical operating points shifts and no longer necessarily coincides with peak and light load conditions. This means that deducing the stability of the system from a restricted analysis of a limited number of operating points becomes very speculative. A methodical approach that covers all hourly operating points throughout a study year is therefore necessary. This paper offers a platform based on supervised and unsupervised machine learning techniques along with optimal power flow, steady-state, and dynamic simulation tools to perform deterministic time-series simulations. The platform allows rapid time-series preliminary assessments of transient stability (i.e., rotor angle stability) in the context of high renewable penetration. As a case study, the proposed platform is tested to assess the transient stability of an IEEE-39 test system augmented with renewable energy resources. Various generation expansion scenarios are considered to show how the platform can be used to conduct grid scenario analyses by investigating the effect of different energy mixes, renewable penetration levels, and renewable siting.

Research on the Control Algorithm of Full Sea Heavy Load Proportional Seven-Function Hydraulic Manipulator Based on Load Sensing

Abstract An underwater manipulator is one of the most commonly used tools in offshore operations. In the face of the unknown environment of the deep sea and the uncertainty of the operation target, the underwater manipulator needs good control stability and higher control efficiency to prevent accidents, which puts forward higher requirements for the control of the manipulator. Underwater manipulators often need to work under heavy loads and to perform tasks efficiently under light loads, which is crucial for efficient control under load. In this paper, a control algorithm based on proportion and derivative feedback control for an all sea depth load proportional hydraulic manipulator is proposed. The feasibility and progressiveness of this algorithm are verified by building kinematic and dynamic models, building physical platforms for tests, and building sea trial acceptance.