As part of the pre-conceptual design activities for the European DEMOnstration plant, a carefully selected set of safety analyses have been performed to assess plant integrated performance and the capability to achieve expected targets while keeping it in a safe operation domain. The DEMO divertor is the in-vessel component in charge of exhausting the major part of the plasma ions’ thermal power in a region far from the plasma core to control plasma pollution. The divertor system accomplishes this goal by means of assemblies of cassette and target plasma facing units modules, respectively cooled with two independentheat-transfer systems. A deterministic assessment of a divertor in-vessel Loss-of-Coolant Accident is here considered. Both Design Basis Accident case simulating the rupture of an in-vessel pipe for the divertor cassette cooling loop, and a Design Extension Conditions accident case considering the additional rupture of an independent divertor target cooling loop are assessed... [more]

A fundamental strategy for utilizing green energy from renewable sources to tackle global warming is the microgrid (MG). Due to the predominance of AC microgrids in the existing power system and the substantial increase in DC power generation and DC load demand, the development of AC/DC hybrid microgrids (HMG) is inevitable. Despite increased theoretical efficiency and minimized AC/DC/AC conversion losses, uncertain loading, grid outages, and intermittent complexion of renewables have increased the complexity, which poses a significant threat toward system stability in an HMG. As a result, the amount of research on the stability, management, and control of HMG is growing exponentially, which makes it imperative to recognize existing problems and emerging trends. In this survey, several strategies from the most recent literature developed to address the challenges of HMG are reviewed. Power flow analysis, power sharing (energy management), local and global control of DGs, and a brief ex... [more]

Depending on the temperature difference between the hot and cold sides of the thermoelectric generator (TEG), the output performance of the TEG can be produced. This means that it is necessary to force a TEG based on robust maximum power point tracking (MPPT) to operate close to its MPP at any given temperature or load. In this paper, an improved fractional MPPT (IFMPPT) is proposed in order to increase the amount of energy that can be harvested from TEGs. According to the suggested method, fractional order control is used. A moth-flame optimizer (MFO) was used to determine IFMPPT’s optimal parameters. A comparison of the results obtained by the MFO is made with those obtained by a particle swarm optimizer, genetic algorithm, gray wolf optimizer, seagull optimization algorithm, and tunicate swarm algorithm in order to demonstrate MFO’s superiority. IFMPPT’s primary objective is to enhance dynamic responses and exclude steady-state oscillations. Consequently, incremental resistance and... [more]

Transformers and circuit breakers are essential equipment in traction power supply systems. Once a fault occurs, it will affect the train’s regular operation and even threaten passengers’ personal safety. Therefore, it is essential to diagnose the faults of the transformers and circuit breakers of the traction power supply system. At present, power companies have made many achievements in fault diagnosis of power equipment, but there are still problems with real-time and accuracy. The Internet of Things (IoT) is a technology that connects different types of terminal devices for information exchange and communication to achieve intelligence. It includes data acquisition and transmission, information interaction, processing, and decision-making from bottom to top. It uses sensor terminals to obtain real-time status information on electrical equipment. Moreover, it conducts real-time monitoring and intelligent processing of the equipment status of the traction power supply system. In this... [more]

Organic-matter-hosted pores are fundamental pore spaces in shale reservoirs, which largely control the expulsion and storage of oil and gas. However, the strong heterogeneity of organic pores greatly increases the complexity of the pore network in shale reservoirs, which make shale reservoir evaluation challenging. The heterogeneity of organic pores in shale reservoirs has beenone of the hottest topics of recent years. In this review, the heterogeneity of organic pores in shale reservoirs and their controlling factors are systematically summarized. The formation and evolution of organic pores in shale reservoirs are directly linked to hydrocarbon generation and expulsion,and the heterogeneity of organic pores is a result of various geological and geochemical factors. The development and heterogeneity of organic pores are basically controlled by the differences in kerogen types and maceral compositions of shale deposits, which are mainly attributed to the differencesin hydrocarbon gener... [more]

In order to clarify the influence in the volcanic mode and structure on the oil reservoirs, the volcanic reservoir characteristics, volcanic eruption pattern, and volcanic eruption period of the third member of the Shahejie formation in the Dagang Oilfield Zao35 fault block are studied by combining logging, 3D seismic, and production data, and to provide geological basis for the subsequent development of volcanic reservoirs. The results show that the volcanic body of the Zao35 fault block is jointly controlled by the fissure-centered eruption mode, and there are three strings of bead-shaped eruption centers as well as a fault overflow channel. Based on the seismic response characteristics, the volcanic rocks can be divided into three main eruption cycles. Moreover, combined with the relatively stable mudstone interlayer encountered by the single well, it can be further divided into eight volcanic eruption periods. There are three different lava units in the overflow facies of each stag... [more]

In this paper, an ocean wave energy conversion system (OWECS) is modeled and experimented in the Yellow Sea near Lianyungang port, and an optimized control method based on the sliding mode control is proposed to improve the efficiency of OWECS. Firstly, a motion model of a double-buoy OWECS is presented using a complex representation method, and the analysis results indicate that the efficiency of converting ocean wave energy into the outer buoy’s mechanical power is highest in a suitable ocean wave period. Secondly, a double-buoy OWECS is constructed and experimented in the Yellow Sea near Lianyungang port, which verified the correctness of the above analysis results. Lastly, in order to further improve the efficiency of the double-buoy OWECS, a sliding mode control method based on a linear generator is proposed to realize the phase synchronization between the outer buoy and ocean waves, and the simulation results may be beneficial for the next ocean test of the double-buoy OWECS.

The dynamic performance of the DC bus significantly influences the impedance characteristics of MMC and the system stability in a high-voltage direct current system. However, most of the existing MMC-HVDC system stability research simplifies the DC side as an ideal voltage source and ignores the impacts of voltage feedforward control, which affects the accuracy and practicability of stability analysis. In this paper, a sequence impedance model considering both DC voltage control and voltage feedforward control is developed, and the necessity of considering DC control and voltage feedforward control for MMC-HVDC stability analysis is illustrated. Then, the impact of control parameters on MMC-HVDC impedance is discussed, and the boundary conditions of control parameters are also derived. Finally, a method of control parameters design and impedance optimization for MMC-HVDC based on the stability boundary is proposed. Compared to the traditional optimization method, the system stability i... [more]

Energy deposition for flow and flight control has received significant interest in the past several decades due to its potential application to high-speed flow and flight control. This paper reviews recent progress and recommends future research.

The main challenges of the input current control in synchronous DC-DC buck converters are the nonlinear model of the system, changes of the operating point in a wide range, and the need to use an input LC filter for current smoothing, which may result in the instability of the closed-loop system. In this paper, a step-by-step approach is developed for the design and improvement of a PI-feedforward closed-loop controller. It is shown that a linear PI controller cannot stabilize the closed-loop system properly during wide changes in model parameters, e.g., an equivalent series resistance of the input filter. To cope with the stability issues, a fixed-frequency sliding mode controller (SMC) has been developed in this paper for the implementation of an electro-mechanical actuator (EMA) emulator. Moreover, a systematic approach is proposed for controller tuning and the selection of the SMC’s gains. To achieve high power efficiency, high-frequency GaN switches are used for the practical impl... [more]

In this two-phase study, it was shown that a mixture with equal parts of manure and resulting animal blood was the optimal combination for obtaining biogas and biol. A quadratic growth trend in variable gas pressure over time—as well as its behavior—was confirmed for pHs around the neutral value for the substrate used in both the pilot phase and in the microplant, which had a mechanical implementation and mechatronic system for the control of variables that intervene in the anaerobic digestion process; this allowed for the confirmation of the results found in the first phase of research—without concerns that a lack of control over the process variables would cause—in such a way that it constituted a path for the industrialization of the waste treatment process in slaughterhouses that could be optimized by the use of the optimal combination that produces the greatest cm3 amount of gas. Anaerobic digestion in biodigesters is carried out at different constant temperature values within the... [more]

The increasing environmental concerns due to emissions from the shipping industry have accelerated the interest in developing sustainable energy sources and alternatives to traditional hydrocarbon fuel sources to reduce carbon emissions. Predominantly, a hybrid power system is used via a combination of alternative energy sources with hydrocarbon fuel due to the relatively small energy efficiency of the former as compared to the latter. For such a hybrid system to operate efficiently, the power management on the multiple power sources has to be optimised and the power requirements for different vessel types with varying loading operation profiles have to be understood. This can be achieved by using energy management systems (EMS) or power management systems (PMS) and control methods for hybrid marine power systems. This review paper focuses on the different EMSs and control strategies adopted to optimise power management as well as reduce fuel consumption and thus the carbon emission fo... [more]

In this paper, electromagnetic multi-step transmissions are introduced as a method for increasing the torque and efficiency of electric vehicle driving motors. Motors using permanent magnets have a limited ability in increasing the speed as the back electromotive force increases as the speed increases. The electric vehicle driving motor performs field-weakening controls to increase the speed after the rated point. Field-weakening control increases the rotor’s speed by weakening the magnetic flux of the field. At this time, the output is constant as the speed increases. Motors have voltage limits, which also affect the maximum speed of the motor. In order to improve these constraints, there is a case study of electromagnetic shifting phenomena. Examples of the research include the wye-delta method and the method of changing the number of equivalent serial turns. As in the case of previous studies, the problem of increasing back electromotive forces as the speed increases is solved. In t... [more]

In this paper, a modified design for a thermoelectric distiller is proposed, constructed, and tested. The design modifications include adding an inclined cover for the thermoelectric module and a cooling fan. The thermoelectric module and the fan were operated by an open loop or a feedback control to have the desired productivity. As the distiller productivity depends on the operating conditions, these operating conditions are investigated to find the best performance with the highest pure water productivity. Furthermore. a comparison between the closed and the open loop for driving the cooling fan with different operating conditions is conducted. In this work, the mathematical model of the proposed distiller is derived. Experimental results illustrate the robustness of the proposed approach and they show that the suggested thermoelectric distiller with feedback control, for both cases with MPC and PID controllers, can increase pure water productivity by up to 150% when compared with t... [more]

Differential protection normally detects short circuits and ground faults in the windings of a power transformer and its terminals. Inter-turn faults refer to flashovers among the electrodes that arise only in a similar type of physical winding. Inter-turn faults can be examined when the adequate sum of turns is served as short-circuited. In electrical protection, it is difficult to detect inter-turn faults. An inter-turn fault of small magnitude is based on the limited number of turns that resultantly provide a large quantity of current. Due to this reason, protection that comes from the differential scenario possesses a higher degree of sensitivity without causing unwanted operations during external faults. In this paper, a protection-based stability method is proposed whereby external voltages are applied at the low-voltage (LV) side of the transformer while keeping the high-voltage (HV) side short-circuited. This was conducted using a three-phase power transformer (rating: 100 MVA,... [more]

The topic of reducing exhaust gas emissions from internal combustion engines in the areas of port and coastal waters is in line with the assumptions of the climate policy. The publication presents a proposal to reduce the energy associated with the movement of port vessels through the use of a specific pattern (shape and size) of their movement. In addition to controlling the formation of tugboats, the authors propose the use of a multi-agent system offering elements of autonomous control of the vessels, which adjusts the parameters of the formation depending on the tasks performed. The results of tests for four tugboats with a hull length of 32 m and a maximum speed of 13 knots, moving in formations of eight different configurations, were analyzed. Studies conducted on the basis of a simulated exit and return to port scenario at a distance of 11.4 nm showed the possibility of reducing energy consumption required for movement by 5.8% to even 57.6% for tugboats moving one after another,... [more]

Generally, utilities regulate the voltage on the long power distribution line within a permissible range by using a step voltage regulator (SVR), which is located around the middle of the line and operates according to the condition of the line current. However, as large-scale distributed generations (DG’s) are interconnected into distribution lines, it is difficult to maintain the line voltage properly owing to bi-directional power flow or reverse power flow. Therefore, this paper proposes a novel SVR tap-changing algorithm to solve the problem, considering line load conditions and reverse power flow. Its validity is verified through the PSCAD/EMTDC software tool and simulations.

Discussed in this study is a bidirectional power control technique for a three-phase grid connected inverter under different unbalanced grid conditions. Prior researchers have focused on either solving the unbalanced problem or controlling the power. However, this paper addresses both issues: solving the unbalanced problems of the point-of-common-coupling (PCC) voltages and grid currents, and reducing the large ripple in the real and reactive power while also applying a bidirectional power control under weak grid conditions. A phase-locked loop (PLL) is not required because a simpler PR controller was employed. A symmetrical components extraction method was used. Compared to previous symmetrical component techniques that used complicated transformations, this approach requires less computations. Since the unbalanced load issue has been resolved, other loads connected to the grid will not be impacted. MATLAB Simulink was used in simulation experiments, and a real-time interface platform... [more]

Long-haul heavy-duty vehicles, including trucks and coaches, contribute to a substantial portion of the modern-day European carbon footprint and pose a major challenge in emissions reduction due to their energy-intensive usage. Depending on the hydrogen fuel source, the use of fuel cell electric vehicles (FCEV) for long-haul applications has shown significant potential in reducing road freight CO2 emissions until the possible maturity of future long-distance battery-electric mobility. Fuel cell heavy-duty (HD) propulsion presents some specific characteristics, advantages and operating constraints, along with the notable possibility of gains in powertrain efficiency and usability through improved system design and intelligent onboard energy and thermal management. This paper provides an overview of the FCEV powertrain topology suited for long-haul HD applications, their operating limitations, cooling requirements, waste heat recovery techniques, state-of-the-art in powertrain control, e... [more]

Sensorless control based on high-frequency square-wave voltage injection (HFSVI) is one of the most common sensorless control methods for synchronous reluctance motors (SynRMs). However, the injection frequency for SynRMs cannot be too high due to various factors. As the injection frequency decreases, the dead-time harmonic current will greatly affect the separation of high frequency signals. This paper analyzes the effect of dead-time harmonic current on the HFSVI-based sensorless control performance of SynRMs and proposes a source of position estimation error. Then, a dead-time compensation method suitable for filter-free HFSVI is proposed. It can estimate current vector spatial orientation without any low-pass filters (LPFs) and effectively compensate the impact of dead-time setting. The correctness of the theoretical analysis and the feasibility of the proposed methods in this paper are verified by experiments.

The purpose of this article is to present a methodical approach to increasing the efficiency of a tug with an azimuth stern drive (ASD). The difficulties in the bow-to-bow (as a reverse tractor) operations of an azimuth stern-drive tug, while pulling at the assisted (towed) ship’s bow, are investigated through a parametric study. The authors’ original generic analytical model of a tug in a steady state is utilised. Various design and operation options are also compared, which cover the escort speed, hawser angle, and relative location of the towing point, among others. The latter also means a shift to stern-to-bow operation. The thruster power required and the remaining surplus for executing new alignment (steering) orders are assessed. The study is, thus, aimed at energy savings for the whole operation and, consequently, at long-term harbour-tug-fleet energy effectiveness. The basic output of the present research is the comparison of the behavioural and control patterns of various tug... [more]

The imbalance of data samples and fluctuating operating conditions are the two main challenges faced by vibration data-driven fault diagnosis for the iron core looseness of saturable reactors in UHVDC thyristor valves. This paper proposes a vibration data-driven saturable reactor iron core looseness fault diagnosis strategy named CVG-MFICNN based on CVAE-GAN and MFICNN to overcome the two challenges. This strategy uses a novel 1-D CVAE-GAN model to produce generated samples and expand the training set based on imbalanced training samples. An MFICNN model structure is designed to allow the simultaneous processing of multimodal features such as the SST time-frequency spectrum, time-domain vibration sequence, frequency-domain power spectrum sequence, and time-domain statistics. Using these multimodal features and the MFICNN model, the hidden fault information in vibration data can be effectively mined. An experiment is conducted to collect vibration data of saturable reactors with differe... [more]

A zero-voltage switching (ZVS) H-bridge phase-shifted low-voltage high-current converter with saturable inductors is proposed in this paper. The introduction of saturable inductors solves the short circuit problem caused by high-frequency on−off of the power tube, and effectively inhibits high-frequency voltage oscillation and voltage spikes of the rectifier tube. In addition, when the current flowing through the saturable inductor does not change rapidly, it exhibits a low impedance and consumes very little power. The detailed design process of main parameters in the converter is presented to provide design reference for power supply workers. To verify the effectiveness of design, a 3 kW(15 V/200 A) prototype converter is built. This low-voltage high-current prototype has around 90% efficiency, and can suppress high-frequency voltage oscillation and voltage spikes, avoiding the short circuit problem of power tube, all of which are verified by experimentation.

To improve the control of active power in wind power clusters, an active power hierarchical predictive control method with multiple temporal and spatial scales is proposed. First, the method from the spatial scale divides the wind power clusters into the cluster control layer, sub-cluster coordination layer and single wind farm power regulation layer. Simultaneously, from the temporal scale, the predicted data are divided layer by layer: the 15 min power prediction is deployed for the first layer; the 5 min power prediction is employed for the second layer; the 1 min power prediction is adopted for the third layer. Secondly, the prediction model was developed, and each hierarchical prediction was optimized using MPC. Thirdly, wind farms are dynamically clustered, and then the output power priority of wind farms is established. In addition, the active power of each wind farm is controlled according to the error between the dispatch value and the real-time power with feedback correction... [more]

This article proposes a model-based method for the detection and phase location of interturn short fault (ISF) in the permanent magnet synchronous generator (PMSG). The simplified mathematical model of PMSG with ISF on dq-axis is established to analyze the fault signature. The current residuals are accurately estimated through Luenberger observer based on the expanded mathematical model of PMSG. In current residuals, the second harmonics are extracted using negative sequence park transform and angular integral filtering to construct the fault detection index. In addition, the unbalance characteristics of three-phase current after ISF can reflect the location of the fault phase, based on which the location indexes are defined. Simulation results for various operating and fault severity conditions primarily validate the effectiveness and robustness of diagnosis method in this paper.