DC Type Research Articles

Study on Coordination of Different Types of DC Superconducting Current Limiter and DC Circuit Breaker for Electric Propulsion Aircraft

Study on Coordination of Different Types of DC Superconducting Current Limiter and DC Circuit Breaker for Electric Propulsion Aircraft

Self-powered sensors utilizing single-pillar thermocells with pyrolytic graphite sheet electrodes: harvesting body heat and solar thermal energy

This study investigates the development of self-powered sensors employing single-pillar thermocells to harness body heat and solar thermal energy. A pyrolytic graphite sheet was selected for its low water vapor permeability, and its surface was modified to be hydrophilic to minimize interfacial resistance. Two types of DC–DC converters, Asahi Kasei Microdevices AP4473 and matrix mercury, underwent evaluation for compatibility with these thermocells. The compact 1.5 cm3 (1 cm × 1 cm × 1.5 cm) device effectively powered the AP4473 converter, illuminating a light-emitting diode. A larger device (2.5 cm × 2.5 cm × 1.5 cm) efficiently drove the matrix mercury converter, enabling the operation of bluetooth low-power sensors. These self-powered sensors wirelessly provided humidity and temperature data using solar thermal energy for approximately 4 h per day during peak temperature differences in January. This study showcases the potential of thermocells for sustainable energy harvesting and suggests avenues for future research, such as exploring alternative heat sources like geothermal energy to power these sensors.

Developments and applications of therapeutic tumor vaccines

The incidence and mortality rates of malignant tumors have rapidly increased. Cancer has become the leading cause of death worldwide. Traditional treatment methods such as surgery, chemotherapy, and radiation have limited effectiveness, with poor prognosis, drug resistance, and low specificity. As a result, cancer immunotherapy has emerged as a promising approach in biotechnology. The development and application of tumor vaccines in tumor immunotherapy have garnered significant attention. These vaccines employ TAA or TSA to activate the bodys specific immune response against tumor cells. This review provides an overview of the tumor microenvironment, tumor immunotherapy, and various types of therapeutic cancer vaccines, including peptide, cell, DC, nucleic acid (DNA and mRNA), and neoantigen vaccines. In conclusion, this review summarizes the current progress and future prospects of tumor vaccines.

Optimizing DOCRs coordination when synergizing energy management with V2G using innovative optimization algorithms

This manuscript proposes an optimal coordination approach for directional overcurrent relays (DOCRs) within electric vehicle charging stations (EVCS), considering energy management and Vehicle-to-Grid (V2G) integration. The study focuses on maximizing efficiency and grid interaction in charging stations by addressing the challenge of DOCRs coordination. Three innovative optimization algorithms, namely the Hunger Games Search (HGS), Hunter Prey Optimization (HPO), and Sparrow Search algorithm (SSA), are employed to determine the optimal coordination for the DOCRs and get the time dial setting (TDS) and pickup current (IP) targeting minimum operating time for all DOCRs, considering factors such as load balancing, fault detection, and power quality in three different scenarios. EVSC has two types of charges DC and AC with two modes: V2G mode when EV is discharged into the grid, and G2V mode when EV is charged from the grid. Fast chargers are used to proceed as it can work in two modes V2G and G2V. Through extensive simulations and performance evaluations, the results demonstrate the effectiveness of the proposed approach. The three scenarios are simulated by using ETAP and MATLAB software according to fault location and to achieve voltage regulation and sufficient power for loads to achieved continuity of service for up to 1960.7 kW loads that kept fed. The proposed approach achieved the target of protecting the EVCS in minimum operating time of relays using the three algorithms and SSA introduces the best result more than other algorithms for the relay operating time with reduction up to 21 %.

An Enhanced Series-Connected Offshore Wind Farm (SC-OWF) System Considering Fault Resiliency

The series-connected offshore wind farm (SC-OWF) is a promising offshore wind generation solution to mitigate the need of centralized offshore high-voltage/power converter stations. Predominantly, researchers have focused on the steady-state operation and control of SC-OWFs, without considering the system-level characteristics and ability to ride-through dc side and ac network faults. This paper proposes an enhanced system for SC-OWF applications with fault-resilient capability, where comprehensive circuit configuration and protection strategies are articulated to minimize the negative effects caused by various types of dc and ac faults. For the offshore wind farm architecture, a grouping scheme is adopted where a substation based on disconnectors and diodes is proposed to realize prompt fault bypass/isolation and protection functions in the event of offshore system faults. Additionally, an onshore fault-tolerant modular multilevel converter (MMC) with modified dc-system-oriented control is employed to enable smooth and secure operation under steady-state and fault conditions. The proposed SC-OWF system is quantitatively substantiated by time-domain simulations where four ac/dc fault cases are considered, and the results consolidate the feasibility of the proposed configuration and control, indicating fault resilience of the SC-OWF system. Additionally, size, weight and cost estimations of the proposed offshore substation are presented and compared to a conventional MMC offshore station, to further highlight the merits of the proposed solution.

Investigation of Solar Energy Applications with Design and Implementation of Photovoltaic Traffic Light Signal System for Qatar

The objective of this paper is to promote the use of solar energy in powering traffic signal systems for rural areas in Qatar with no power grid. A photovoltaic system is needed in order to use this energy continuously. The results of the investigation of components, design, and market availability are shown in the paper. Solar cells, which are used for absorbing sunlight and generating electric current, are the main source for the system’s operation. A charge controller is used to control the flow of charge through the battery and to protect the battery from overcharging and deep discharging. A dc-dc converter is used to regulate the output voltage which depends on the type of dc to dc converter. Lead acid batteries are used as the electric energy storage for the PV system to use electrical energy in the absence of sunlight. The principle operation of the system and the feasibility of using it for rural area with no power grid have been studied. For this project, a mount tracker was constructed that enabled the solar panel to be placed at 0, 15, 30, 45, 60, 75 and 90 degree angles in order to determine which angle and what time provides the optimum voltage. Experimental results for different angles of radiation at different times of the day and different days of the year are shown in the paper.

A Novel Multi-Loop PID Controller for Photovoltaic-Grid Interface DC Energy Utilization Farm

This paper proposes a novel control system for control of a hybrid photovoltaic PV farm utilization with alternative power source for DC type loads. A controller consisting of two different controllers is mainly used to regulate the DC-DC converter and also to control power flow from alternative power source to reduce a weighted total sum of all loop errors, to mainly track a given speed reference trajectory depicting the demand for discharge or flow and also to ensure power quality, reliability and stability. The proposed control function is digitally simulated using the MATLAB/Simulink/SimPower System software environment. The dynamic performance of the hybrid system is examined for the control system validation under normal and abnormal operating conditions.

A Novel Multi-loop Fuzzy Logic Dynamic Controller for Wind/Photovoltaic-Grid Interface DC Energy Utilization Farm

This paper proposes a novel control system for control of a hybrid wind/photovoltaic (PV) farm utilization with alternative power source for DC type loads. A controller consisting of six different loop controllers is mainly used to regulate the DC-DC converter to reduce a weighted total sum of all loop errors, to mainly track a given speed reference trajectory depicting the demand for discharge or flow and also to ensure power quality, reliability and stability. The proposed control function is digitally simulated using the MATLAB/Simulink/ SimPower System software environment. The dynamic performance of the hybrid system is examined for the control system validation under normal and abnormal operating conditions.

Analysis of Inter-Turn Short-Circuit Faults in Brushless DC Motors Based on Magnetic Leakage Flux and Back Propagation Neural Network

Inter-turn short-circuit (ITSC) faults are the most common fault types of brushless DC (BLDC) motors used in industry. Fault diagnosis of BLDC motors is of critical importance due to their wide spread applications. Existing diagnosis methods are based on voltage and current analysis which is useful but difficult to identify early faults and fault locations, as these suffer from external disturbances. This paper proposes a new offline method for fault detection based on magnetic leakage flux (MLF) and backpropagation neural network (BPNN) for improving the level of fault diagnosis. The ITSC and MLF are modeled and analyzed theoretically. Then they are verified by finite element analysis (FEM) and experimental tests. Hall sensors are used to form an array to collect MLF signals at different positions outside the test motor. The frequency-domain characteristic matrix of MLF signals is analyzed by BPNN models. The experimental results show that the proposed method can effectively detect ITSCs, and estimate the fault degree and the location of the fault. The method is a promising technology as it is non-intrusive and accurate.

Transformerless partial power converter topology for electric vehicle fast charge

AbstractIncreasing the power rating of electric vehicles (EV) fast charging stations to reduce charging times is considered critical to accelerate the adoption of electric vehicles. Besides increasing the power, other drivers pushing the development of EV fast chargers include the improvement of efficiency and reliability. Partial power converters (PPC) have emerged as an interesting option for some of the power converter stages in fast charging stations due to their potential to increase efficiency and power rating. However, some PPCs operate as switched autotransformers by using high frequency (HF) isolation transformers but without providing galvanic isolation. This is a drawback due to cost, size and losses introduced by the transformer. This paper presents a transformerless DC–DC Type I step‐up PPC for a DC–DC regulation converter for EV fast charging stations. The proposed converter replaces the transformer commonly used in Type I PPC by an impedance network, resulting in a more efficient, cheaper, and less complex converter option. This concept is verified through simulations and experimentally validated with a laboratory prototype.

HARMONIC CANCELLATION IN POWER SYSTEM USING MULTIPULSE AC-DC CONVERTERS

Power quality issues have become a prominent concern within modern electrical systems due to the escalating reliance on sensitive electronic equipment and the integration of renewable energy sources. Sources contributing to these disturbances, encompassing power grid irregularities, switching activities, and nonlinear loads, are thoroughly explored. Using various ideas and techniques, a lot of effort has been done in recent years to reduce total harmonic distortion. Filtering or cancellation are two techniques for harmonic treatment. In this section, we discuss employing a multi-pulse AC to DC conversion strategy to reduce total harmonic distortion. Power quality can be enhanced using multiple pulse converters, and in this research, 6, 12, 18, 24 pulse converters have been simulated and modeled using the MATLAB/Simulink programme. Each one of these converters produces 6-pulse AC to DC conversion, so consistent phase-shift is needed to build many sets of 6-pulse system. As a result, 12-, 18-, 24-, and 30-pulse systems have been created with the necessary phase-shifting angle. Total harmonic distortion (THD) in current supply and ripples present in DC type voltage are reduced, improving the performance of multi-pulse converters[5]. Keywords: Multi-Pulse converters , Total Harmonic Distortion (THD), Harmonics, Ripple Content , Power Quality.

A Unified Capacitor Stress Emulation Method for High-Power Converter Applications

This paper proposes a unified capacitors stress emulation method, which has two unique test capabilities: 1) concurrent electrical stress emulation to AC capacitors and DC capacitors; 2) different electrical stress levels (including different ripple current, ripple voltage, and DC voltage) can be individually controlled for the testing samples. It preserves the advantages of a recently reported method with a minimum required power supply and is robust to testing sample degradation. This method is suitable for application-oriented stress emulation testing with different types of DC / AC capacitors and multiple electrical stresses in high power converter systems. The circuit architecture and testing ability of this method are presented. Moreover, analytical models are derived to size the key components to realize various testing requirements. Proof-of-concept experimental results are presented to verify the feasibility of the proposed test method.

A Unified Self-Super Lift Luo Converter-Based PA-PID and RDP Controlling Algorithms for EV Application Systems

Recently, electric vehicles (EVs) are increasingly used due to its cost-efficiency, reduced maintenance, no fuel consumption, and eco-friendly nature. But, designing the proper converter and controlling units for controlling the speed of the motor used in the EVs is considered as a challenging task. Most of the conventional works developed different types of DC–DC converters and optimization-based controlling topologies for increasing the output of voltage fed to the EVs. Since, it faces problems related to the factors of high power loss, increased harmonic contents, time measures, and inefficient computational operations. Hence, this article objects to developing an advanced and intelligent converter and controlling topologies for improving the overall performance and efficiency of EVs. The main contribution of this work is to develop the Self-Super Lift Luo (SSLLuo) DC–DC converter for regulating and highly boosting the output voltage with reduced harmonics. Also, an optimization-based Phasor Algebraic (PA-PID) Controlling mechanism is developed for generating the controlling signals in order to operate the switching components of the converter circuit. In addition to that, the Regressive Distributed Pattern (RDP) controller is designed for efficiently controlling the current limit of motor the driving circuit. During validation, both the simulation and comparative analysis have been conducted for proving the efficiency and optimal performance of the proposed system.

Selection of a traction electric motor for arctic electric transport

Aim: selection of a traction motor for electric freight transport operating in the Arctic. Methods: To achieve this aim, the main characteristics of existing types of DC and AC electric motors were considered, as well as data on the use of one or another type of motor in modern electric vehicle. Results: A comparative analysis of the most common motors has led to 2 main leaders - a permanent magnet synchronous motor (PMSM) and an induction motor (IM). Both types of motors are fully suitable for solving the aim. However, as it turned out later, PMSM is more often used for light vehicles, while IM in most cases is used for heavier vehicles. Conclusion: As a result of the analysis, it was decided that for electric transport operating in the Arctic, the best option is to use an induction motor as a traction motor.

Load-Frequency and Power Sharing Control in a Multi-Area Power System Using Intelligent Sliding Surface Approach

With the penetration of DGs in power systems, some restrictions such as economic dispatch in non-dispatchable sources, their control technology and voltage/frequency stability may be challenging. In conventional power systems, the transient stability has been obtained by high-inertia of upstream network in all conditions; however, in modern power grids, the micro grids (MGs) which could operate in both islanded mode and grid-connected mode are taken into account to overcome this issue. AC or DC types of DGs usually connect to the loads through power electronic converters, in which for researchers, this issue has been interesting and applicable to continue. When loads have been changed, the frequency has influenced correspondingly and must not exceed the permissible range. Therefore in this paper, this intention has been studied using conventional droop controller and intelligent sliding surface approach (ISSA) to evaluate the DGs effects on load-frequency control. While two or more areas (as some individual MGs) connect to each other via a transmission line, the voltage/frequency stability and power balancing constrained may be changed, which the ISSA is hired to track the frequency changes. To examine this problem, in this paper there are three MGs operate separately to show if the load may not supply, they should connect to adjacent block. If this important concern has not considered, it may cause global black-out. The simulation results obtained by ISSA compared with droop controller method represent the superiority of proposed technique to achieve best power sharing.

Commisioning Test of 3 x 3kW Solar Power Plants for Laboratory Purpose

A laboratory is an important part in the learning and teaching process, therefore, it is necessary to improve both in terms of equipment and laboratory management standards. State Polytechnic of Ujung Pandang has carried out the design process for a solar power plant (SPP) system with a capacity of 3 x 3 kW to support the learning process related to alternative and renewable energy lectures and practicum. One part of the procedure for activating newly installed laboratory equipment is the commissioning test. From the commissioning results, the results show that 3 x 300 Wp and independent 375 Wp SPP can work well with an average DC voltage rating of 80 V and for AC loads with an average voltage of 220 V. All types of loads, both AC and DC can work properly after going through the DC Couple and AC Couple with the inverter.

Development of a two-stage cyclone

The process of separating the transported material from the carrying gas flow in cyclones at grain-processing enterprises is studied. Feed production is accompanied by the formation of fine flour dust which is a valuable component of fermented feed. Aspiration systems of mini-fodder plants do not provide its full capture, which leads to contamination of the premises, as well as the loss of some of the product. During the analysis of designs and ways to improve centrifugal apparatuses, it was determined that installation of additional swirling devices in the cyclone exhaust pipe is promising for cleaning the air flow from fine dust. The design of cyclone with an additional stage of cleaning the air flow from fine flour dust in the outlet nozzle, used in the pneumatic conveying system of mini-fodder plant, is proposed. The diameter of the axial pipe socket is enlarged to accommodate the baffle cone and vortex funnel inside it. The diameter of the outlet nozzle should be smaller than the diameter of the upper base of the vortex funnel to reduce the fine fraction escape from the cyclone. An experimental unit was developed including a charging hopper, pneumatic receptor-diverter, material pipeline, cyclone, filter, and a suction fan. The material used was wheat grain with a moisture content of 16%, crushed on a hammer crusher with a hole diameter of 3 mm in the sieve. Comparative tests of the proposed cyclone with cyclones of the DC and SNT types were carried out, the results of which prove the effectiveness of the proposed design. In the investigated range (from 0.026 to 0.33 kg/s) the efficiency of the two-stage cyclone in feeding the transported material was higher than that of the commercially available discharger cyclones DC.

Novel mouse models based on intersectional genetics to identify and characterize plasmacytoid dendritic cells

Plasmacytoid dendritic cells (pDCs) are the main source of type I interferon (IFN-I) during viral infections. Their other functions are debated, due to a lack of tools to identify and target them in vivo without affecting pDC-like cells and transitional DCs (tDCs), which harbor overlapping phenotypes and transcriptomes but a higher efficacy for T cell activation. In the present report, we present a reporter mouse, pDC-Tom, designed through intersectional genetics based on unique Siglech and Pacsin1 coexpression in pDCs. The pDC-Tom mice specifically tagged pDCs and, on breeding with Zbtb46GFP mice, enabled transcriptomic profiling of all splenic DC types, unraveling diverging activation of pDC-like cells versus tDCs during a viral infection. The pDC-Tom mice also revealed initially similar but later divergent microanatomical relocation of splenic IFN+ versus IFN− pDCs during infection. The mouse models and specific gene modules we report here will be useful to delineate the physiological functions of pDCs versus other DC types.

Comparative assessment of high gain boost converters for renewable energy sources and electrical vehicle applications

Abstract Due to greenhouse gas emissions and the energy crisis, the conventional way of generation of electricity using fossil fuels is being substituted with Renewable Energy Sources (RES) like solar photovoltaics (SPV), fuel cells, wind, etc. The voltage produced by RES is very small in magnitude; therefore, the choice of DC–DC converter is critical for regulating and improving the output of RES to its maximum level. To meet the power requirement for the utility grid and electric vehicles (EV), the voltage must be enhanced. So far, various types of high-gain DC–DC boost converter (HG-BC) topologies have been suggested. An overview of HG-BC topologies for RES and EV applications is presented in this paper, which provides a unique, extensive, perceptive, and comparative analysis of HG-BC topologies. The mathematical modeling and operating principles of each converter topology have been analyzed and discussed. The boost factor (B) and component count for various HG-BC are thoroughly compared for a 0.5 duty cycle using the MATLAB/Simulink tool.

The Electrical Behaviour of Railway Pantograph Arcs

Electric arcing is an unavoidable consequence of the current collection process by sliding contact in railways and metros, and in general in many electrified transportation systems (ETSs). The most relevant consequences in an electrical perspective are: the occurrence of transients triggering resonant behaviour and transient responses, reduction of the energy efficiency of the system, conducted and radiated disturbance, in particular for the new radio systems widely employed for signalling and communication. The involved parameters are many (type of materials, current intensity, DC and AC supply, relative speed, temperature), as well as the studied characteristics (arc instability and lifetime, dynamic behaviour, electrical system response, radiation efficiency and coupling to external radio systems). This work reports the state of the art in arc modelling, arcing experimental characterisation, interaction with the supply system, radiated emissions and disturbance to radio systems, providing a complete description of phenomena and of reference data, critically discussing similarity and differences between sources. Proposed arc models are many with different assumptions and simplifications for various applications, so that a critical review and discussion are a necessity, considering the many different approaches and not-so-obvious applicability. The comparison with experimental results highlights unavoidable discrepancies, also because of intrinsic arc variability and for the many involved parameters and operating conditions. The impact of the arc as embedded in the railway system is then considered, speaking of conducted and radiated phenomena, including interference to radio communication systems and arc detection. The most prominent effect for conducted emissions is the excitation of system resonances, including the LC filters onboard rolling stock and substations in DC railways, with consequences for disturbance and energy efficiency, and this is discussed in detail. Conversely, for high frequency emissions, the attenuation along the line circuit is significant and the effective distance of propagation is limited; nevertheless radiated electromagnetic field emissions are a relevant source of disturbance for radio systems within the ETS premises and outside (e.g., at airports). The published approaches to quantify performance reduction are discussed with emphasis on experimental methods.