Real-time Testing System Research Articles

DC microgrid for EV charging station with EV control by using STSM controllers

Abstract This study explores innovative control strategies for electric vehicle (EV) charging stations in a DC Microgrid powered by solar and wind energy. A new methodology regulates the dc-link voltage through various converters while a modified vector control method enhances the performance of switched reluctance motors (SRMs). The implementation of super twisting sliding mode (STSM) controllers show superior performance compared to traditional PI and Fuzzy controllers. The design of an asymmetrical converter with four battery banks also minimizes charging durations. The real-time test system (RTS) effectively managed power generation within a DC microgrid, demonstrating a stable voltage at the DC bus despite variations in total generation from photovoltaic (PVS) and wind systems. In Case 1, the controller successfully maintained power balance while charging electric vehicles and managing DC loads. During load torque adjustments, the system maintained a steady motor speed of 320 RPM even with a load torque increase from 5 Nm to 50 Nm at 3 s, showcasing its robust vector control strategy. Notably, the system facilitated a reverse operation at 10 km h−1 (80 RPM) by seamlessly adjusting the engine’s reference speed from 80 RPM to −80 RPM at t = 4.0 s. The vector control causes the engine speed heading to be opposite in a natural manner., indicating its innovative capability to handle diverse operational scenarios. The MATLAB/Simulink package serves as the foundation for the proposed model, which is then integrated into OPAL-RT modules to create a Hardware-in-the-Loop (HIL) system for showcasing diverse outcomes. Different outcomes are deliberated with validated justifications of the suggested approach. The research is linked to Sustainable Development Goals 7 (Affordable and clean energy) and 13 (Climate action).

Influence of Temperature and Bedding Planes on the Mode I Fracture Toughness and Fracture Energy of Oil Shale Under Real-Time High-Temperature Conditions

The anisotropic fracture characteristics of oil shale are crucial in determining reservoir modification parameters and pyrolysis efficiency during in situ oil shale pyrolysis. Therefore, understanding the mechanisms through which temperature and bedding planes influence the fracture behavior of oil shale is vital for advancing the industrialization of in situ pyrolysis technology. In this study, scanning electron microscopy (SEM), CT scanning, and a real-time high-temperature rock fracture toughness testing system were utilized to investigate the spatiotemporal evolution of pores and fractures in oil shale across a temperature range of 20–600 °C, as well as the corresponding evolution of fracture behavior. The results revealed the following: (1) At ambient temperature, oil shale primarily contains inorganic pores and fractures, with sizes ranging from 50 to 140 nm. In the low-temperature range (20–200 °C), heating primarily causes the inward closure of inorganic pores and the expansion of inorganic fractures along bedding planes. In the medium-temperature range (200–400 °C), organic pores and fractures begin to form at around 300 °C, and after 400 °C, the number of organic fractures increases significantly, predominantly along bedding planes. In the high-temperature range (400–600 °C), the number, size, and connectivity of matrix pores and fractures increase markedly with rising temperature, and clay minerals exhibit adhesion, forming vesicle-like structures. (2) At room temperature, fracture toughness is highest in the Arrester direction (KIC-Arr), followed by the Divider direction (KIC-Div), and lowest in the Short-Transverse direction (KIC-Shor). As the temperature increases from 20 °C to 600 °C, both KIC-Arr and KIC-Div initially decrease before increasing, reaching their minimum values at 400 °C and 500 °C, respectively, while KIC-Shor decreases continuously as the temperature increases. (3) The energy required for prefabricated cracks to propagate to failure in all three directions reaches a minimum at 100 °C. Beyond 100 °C, the absorbed energy for crack propagation along the Divider and Short-Transverse directions continues to increase, whereas for cracks propagating in the Arrester direction, the absorbed energy exhibits a ‘W-shaped’ pattern, with troughs at 100 °C and 400 °C. These findings provide essential data for reservoir modification during in situ oil shale pyrolysis.

Real-time hybrid test method for floating wind turbines: Focusing on the aerodynamic load identification

Since the development of floating wind turbine (FWT) shows a rapid trend towards larger capacity and larger rotor size, the traditional full-model basin test method has encountered limits. Especially the balance between the wind generation system (WGS) size and scale ratio of the model FWT system. Under such circumstances, the hybrid model test method provides the possibility to improve the FWT model test. In the hybrid model test method, the original physical model system is divided into physical subsystem and numerical subsystem, and the data acquisition and process module between the 2 subsystems plays an important role. In this paper, a framework of real-time hybrid test (RTHT) system is setup firstly, which combines physical model wind turbine and motion platform. The damping modification to the corresponding numerical code is applied to improve the motion calculation accuracy. Delay implementation is employed to avoid motion divergence. Then a simulation loop is setup in numerical environment to study the identification of aerodynamic load. The influence of identification accuracy to the RTHT result is analyzed. Lastly, the dual-accelerometer method of aerodynamic load identification is employed in the proposed RTHT system. Decay tests and irregular wave only tests are carried out to validate the aerodynamic load identification method. The capability and potential of the RTHT method of floating wind turbine model test is preliminary proved in the work of this paper.

Stability prediction method of time-varying real-time hybrid testing system on vehicle-bridge coupled system

In recent years, real-time hybrid testing (RTHT) has been applied for the dynamic testing of high-speed trains running on bridges. A guarantee of stability for the RTHT system is essential to achieve a safe and reliable result. However, the inherent time-varying characteristics of the vehicle-bridge coupled system pose challenges to RTHT stability prediction. This study aims to develop a stability prediction method specifically tailored for time-varying RTHT system. Firstly, the vehicle-bridge coupled RTHT was modelled using a discrete state–space representation with a comprehensive consideration of the time-varying vehicle-bridge interaction and the dynamics of the shaking table. Subsequently, a time-varying stability criterion was derived from the periodic time-varying state matrix, forming the basis for a relative stability prediction method. The validity of the proposed method was confirmed through simulations and experiments employing a single-axle interaction within the vehicle-bridge coupled RTHT system. The coupled system consisted of a quarter-car model and simply supported beams were used as an example to evaluate the stability and accuracy of the time-varying RTHT. The results showed that the stability increased with increasing vehicle speed. Reducing the pure time delay of the shaking table improved both stability and accuracy. Increasing the effective frequency of the shaking table improved the accuracy but may reduce the stability of the RTHT.

Real time performance assessment of utility grid interfaced solar photovoltaic plant

Continuous monitoring of large-scale solar photovoltaic (PV) installations is necessary to check the deterioration and monitor the performance of the PV plant. Fault diagnosis is crucial to ensure the PV plant operates safely and reliably. This paper presents a diagnosis methodology based on current-voltage (I-V) and PV characteristics to monitor and assess the behavior of solar PV. In this paper, I-V curve characterization using an I-V curve tracer is used to check the deterioration and diagnosis of the PV panels. The real-time performance of the 50.4 kWp rooftop solar grid interfaced PV plant is investigated and analyzed using I-V and PV curve tracers in real-time conditions. The overall performance of solar PV is assessed on a real-time test system in different scenarios such as variable climatic conditions, partial shading conditions, aging of solar panels, short circuit conditions, and dust decomposition. Furthermore, the performance assessment of solar PV is evaluated using performance indicators such as open circuit voltage index, short circuit current index, fill factor, and performance ratio.

Study on transient thermal state of steel piston in diesel engine under cold start condition

The thermal load issue of pistons remains a topic of active research, especially the transient thermal state of steel pistons in diesel engines under cold start conditions has not been studied in depth. In this paper, a new steel piston power assembly was designed and developed on the basis of a small-bore diesel engine. A real-time temperature test system for the steel piston temperature field was developed to address the problem of the inability to obtain real-time temperature data. The test system was applied to the steel piston to investigate the transient variations in temperature field, thermal stress, and thermal deformation at different starting temperatures. The results show that the temperature field of steel pistons exhibits exponential growth in the early stage of cold start and then tends to stabilize after about 44 s. The lower the cold start temperature and the closer the monitoring points are to the high-temperature combustion gas, the faster the rate of temperature rise. The thermal stress of the steel piston initially increases rapidly, then decreases, and subsequently increases again until reaching a stable level. The lower the starting temperature, the longer the thermal stress inflection point of the monitoring point will be. The variation of thermal deformation of the steel piston follows the same trend as that of the temperature field.

Development and validation of a test system for determining the polymorphism in the DGKH and PPP1R1C genes associated with body weight of sheep

Relevance. National sheep breeding is lagging behind other branches of animal husbandry considering using of modern DNA technologies. The search for new genes — potential candidates associated with economically significant traits — is relevant for a more complete disclosure of the genetic potential of sheep. An earlier genome-wide association study showed that the DGKH and PPP1R1C genes had a certain effect on body weight of sheep at birth and at the age of 90 days. In this regard, a more detailed study of polymorphism in the DGKH and PPP1R1C genes can deepen understanding of growth and development processes in domestic sheep, so we have chosen these genes as targets for the experiment.Methods. Primers and probes were selected for amplification of a fragment with targeted SNPs in the DGKH and PPP1R1C genes with a length of 68 nucleotide pairs based on the reference DNA sequence on the 10th (NC_056063.1) and the 2nd chromosome (NC_056055.1) sheep represented in NCBI. To determine polymorphism, real-time PCR-based test systems were developed. Genotypes were determined using a multiparametric graph. The test systems were tested on 147 sheep of the southern meat breed.Results. The developed test systems for promising DGKH and PPP1R1C genes allowed to clearly determine sheep genotypes based on using the PCR-RT. All three genotypes (T/T, C/T, and C/C) were identified in the DGKH gene. No homozygous genotype (T/T) was identified in the PPP1R1C gene in the studied population. The test systems are suitable for routine DNA analysis in molecular genetic laboratories.

Stability prediction method for real-time hybrid test system based on the measured dynamics of physical test system

The stability analysis of real-time hybrid test (RTHT) is crucial for the division of numerical and physical substructures, performance evaluation of loading system controllers, and feasibility judgment of RTHT systems. Existing stability analysis methods involve the parameter identification and numerical modeling of physical test systems. In contrast, an RTHT involves conducting a physical test on the hard-to-model part. Therefore, it is difficult to accurately model the physical substructure as well as the loading and acquisition systems. In this study, an RTHT stability prediction method based on the measured dynamics of the physical test system was developed, which avoid the tedious numerical modeling of the physical test system. The effectiveness of the stability prediction method was verified through numerical simulation and the experimental testing of a multi-degree-of-freedom shaking table RTHT. The experimental results showed that the accuracy of the developed stability prediction method was higher than that of the model-based stability prediction method by 35.1 %. The stability prediction method developed in this study simplifies the stability analysis of RTHT and will help determine the feasibility of test in advance.

Design of Real-time Test System for Servo Stabilization System Based on Matlab/xPC

For the barrel and static drift problem in the working process of the servo-stabilization system of an unmanned firing module, a simulation test system is built by using the Matlab/xPC real-time platform. The CAN communication card is driven by the Simulink S-function, and communication between the test system and the servo stabilization system is realized. The fast Haar wavelet threshold processing method is used to de-noise the gyro speed signal, and the de-noising effect of the signal processor is simulated and verified in the physical system. The results show that the servo stability test system has strong real-time performance, and the performance of the Haar wavelet de-noising algorithm is good. The system has a broad application value.

Pounding Mitigation Design and Real-Time Hybrid Simulation for a Novel Viscous Damper Applied in Bridges

When the actual displacement of viscous damper exceeds the stroke limit, excessive pounding force may be generated, resulting in damage to the damper. To address this issue, a novel viscous damper with variable stiffness, simple processing, and good economy is proposed. First, the load-displacement relation of the novel viscous damper is established through theoretical analysis and experimental studies. Second, numerical simulations and a series of parametric analyses are conducted to analyze the pounding mitigation effect of the proposed damper. Third, real-time hybrid simulation (RTHS) for considering the pounding effect of the novel viscous damper is presented. Finally, design recommendations for the pounding mitigation design of the novel viscous damper are given. The results show that the novel viscous damper effectively reduces the amplitudes of the pounding force and acceleration by 25% and 24%, respectively. The Fourier power of acceleration decreases in the region from 0.6 Hz to 3.3 Hz. The results of RTHS demonstrate that the real-time hybrid testing system can effectively simulate the pounding effect of the proposed damper. However, the normalized error peak value of velocity between RTHS and the reference result exceeds 10%, indicating that the proposed damper considering the pounding effect imposes new requirements to the real-time hybrid testing method.

A real-time hybrid testing based on shaking table and actuator for cable tray systems

For precisely disclosing the seismic performance of cable tray systems, one novel Real-Time Hybrid Testing based on Shaking Table and Actuator (RTHT-STA) is proposed in this paper. In the proposed method, one shaking table is used to simulate the ground motion, and one servo-hydraulic actuator controlled with displacement mode is set up on the shaking table for truly simulating the transverse shear boundary conditions between the numerical substructure and the experimental substructure of cable tray systems. The advantage of the proposed method is accurately realizing the loading requirements of high-precision large deformation on cable tray systems. The effectiveness and accuracy of the proposed method are validated by numerical simulations and experimental tests. The experimental results show that the real-time hybrid testing system is stable and reliable. The correlation coefficients between the results of the proposed method and those of the traditional shaking table tests are higher up to 91.78%. The results indicate the effectiveness and the high accuracy of the proposed RTHT-STA for cable tray systems. The RTHT-STA provides an economical and precise investigation strategy for disclosing the seismic performance of cable tray systems and may have broad application prospects in the field of communication engineering and civil engineering.

Real-Time Hybrid Testing of a Floating Offshore Wind Turbine Using a Surrogate-Based Aerodynamic Emulator

AbstractPhysical modeling of floating offshore wind turbines (FOWTs) is challenging due to the complexities associated with the simultaneous application of two different scaling laws, governing the hydrodynamic and aerodynamic loading on the structure. To avoid these issues, this paper presents a real-time hybrid testing (RTHT) strategy in which a feedback loop, consisting of an on-board fan and control algorithm, is utilized to emulate the aerodynamic forces acting on the FOWT system. Here, we apply this strategy to a 70th-scale IEA Wind 15 MW reference wind turbine mounted on a version of the VolturnUS-S platform. Unlike other similar methods, which directly simulate the aerodynamic loads for the fan’s control using an aerodynamic code running in parallel with the experiment, this example utilizes a surrogate model trained on numerical model data calculated in advance. This strategy enables high-fidelity numerical model data, or even physical data, to be included in the aerodynamic emulation, by removing the requirement for real-time simulation, and, therefore, potentially enables more accurate loading predictions to be used in the experiments. This paper documents the development of the real-time hybrid testing system in the Coastal Ocean And Sediment Transport (COAST) Laboratory at the University of Plymouth in the UK, including the hardware, software, and instrumentation setup, and demonstrates the power of the surrogate-based aerodynamic emulator based on numerical data calculated using OpenFAST.

Real-time multiplex PCR method for detection of A. veronii A. caviae A. salmonicida

As a result of the experiments, the parameters for setting up a polymerase chain reaction were developed for the accelerated identification of Aeromonas spp. The design of species-specific primers was performed, the reaction parameters were selected, the specificity was checked, and the optimal amplification time was selected. As a result of this study, a multiplex real-time PCR test system was developed for the simultaneous detection of A. salmonicida, A. caviae and A. veronii. The sensitivity of the developed protocol was 5.56 pg/µl. The data obtained will allow for accelerated screening of these pathogens.

Modeling and Stability Analysis of Distributed Secondary Control Scheme for Stand-Alone DC Microgrid Applications

Stand-alone DC microgrids have multiple distributed generation (DG) sources that meet the required demand (load) by using droop control to achieve load (current) sharing between the DGs. The use of droop control leads to a voltage drop at the DC bus. This paper presents a distributed secondary control scheme to simultaneously ensure current sharing between the DGs and regulate the DC bus voltage. The proposed control scheme eliminates the voltage deviation and ensures balanced current sharing by combining the voltage and current errors in the designed secondary control loop. A new flight-based artificial bee colony optimization algorithm is proposed. This selects the parameters of the distributed secondary control scheme to achieve the objectives of the proposed controller. A state–space model of the DC microgrid is developed by using eigenvalue observation to test the impacts of the proposed optimized distributed secondary controller on the stability of the DC microgrid system. A real-time test system is developed in MATLAB/Simulink and used in a Speedgoat real-time simulator to verify the performance of the proposed control scheme for real-world applications. The results show the robustness of the proposed distributed secondary control scheme in achieving balance current sharing and voltage regulation in the DC microgrid with minimal oscillations and fast response time.

Experimental investigation of the discharge valve dynamics in an oil-free linear compressor for Joule-Thomson throttling refrigerator

• A visual and real-time test system was set up to investigate dynamics of the linear compressor discharge valve. • The principle of the valve movement characteristics on exhaust loss is discussed. • The effect of valve dynamics on the thermodynamic efficiency of the free-piston oil-free linear compressor is studied. As the core component of the linear compressor which is a research hotspot of Joule-Thomson (J-T) throttling refrigerators for space applications, the discharge valve has a significant impact on their reliability and efficiency. Therefore, studying the dynamic characteristics of the discharge valve is indispensable which contributes to improving the compressor efficiency. Based on the oil-free linear compressor independently developed by the laboratory, a visual and real-time test system was set up to investigate the dynamics of the discharge valve and the compressor performance. While varying the parameters including piston stroke, valve stiffness, and operating frequency, the movement characteristics of the discharge valve and the thermodynamic efficiency of the compressor were measured and studied. The detailed principle of the valve movement characteristics on exhaust loss is discussed in the analysis of the results. The better discharge valve thickness for the linear compressor was selected. The experimental results indicated that the thermodynamic efficiency with the valve thickness of 0.152 mm is higher than 0.102 mm and 0.203 mm. The research in this paper will provide a valuable reference to design a discharge valve with high-efficiency and positive behavior for the linear compressor.

Effects of damage on resistivity response and volatility of water-bearing coal

A series of experimental geophysical methods with resistivity as the key parameter provide strong support for predicting and providing early warnings of geological disasters. In this study, coal samples with similar P-wave velocities and pore distributions were screened, and a weighing method was used to control the water content of the coal samples. A real-time test system was independently constructed to conduct uniaxial compression tests on these coal samples and synchronously monitor resistivity and acoustic emission (AE) data. The results show that resistivity obviously characterizes the process of coal failure under load. The development of microfractures causes fluctuations. The resistivity changes relatively smoothly before the development of fractures, and resistivity fluctuations are obvious during the development of fractures. The resistivity fluctuation range reaches the maximum when the whole fracture occurs at the stress peak, but the presence of water weakens the resistivity fluctuations during the whole process of failure. Water migration causes circuit reconnection and changes the fluctuations. With increasing water content, the uniaxial compressive strength (UCS), elastic modulus (E) and maximum AE amplitude decrease. The resistivity variation at the peak value also decreases. Under the condition of 9.2% water content, the resistivity variation at the peak stress is only 2.52%. The results prove that violent fluctuations of resistivity correspond to the development of microfractures in the sample, and the amplitude of the fluctuations is positively correlated with the degree of damage and fracture. The volatility index (Resistivity Standard Deviation, RSD) is established to describe the degree of resistivity fluctuation, and the peak value occurs when the AE energy increases sharply. The establishment of a volatility index aims to provide a new parameter for rock damage and dynamic disaster prediction technology.

A 4-Channel High-Precision Real-Time Pressure Test System for Irregularly Variable High Temperature Environments

In this study, a 4-channel high-precision pressure test system was designed. It implements high-precision measurement of pressure parameters at multiple test points in situ and synchronously in irregularly variable high-temperature environments. The test system consists of a pressure–temperature double-parameter composite sensor along with signal acquisition, temperature compensation algorithm processing, and real-time online display modules. The temperature-sensitive chip of the sensor was integrated on the surface of the differential pressure-sensitive chip for in-situ temperature compensation. The collected pressure-temperature parameters were calculated and displayed using the temperature compensation algorithm processing and real-time online display modules. Finally, a high-precision pressure test was conducted. The proposed test system realizes the pressure test in high-temperature environments with irregular variations in the range of 24–400 °C, with a test error of less than 0.95% and a sensitivity of 6.378 mV/kPa. The study results can be used for real-time monitoring of high-precision pressure of key components operating in irregularly variable high-temperature environments, which provides a significant guarantee for the normal operation of equipment.

PCR-amplified Immunoassay (Immuno-PCR): Principle of the Method, Variants of Execution, Possibilities and Prospects of Use for the Detection of Pathogenic Biological Agents

Enzyme immunoassay and polymerase chain reaction have become the «gold standard» for the detection of biological pathogens. The method of amplified immunoassay – immuno-PCR allows to combine both methods into a single platform to preserve their advantages and to achieve high sensitivity of the analysis. The purpose of this work is to consider the possibilities and prospects of using PCR-amplified immunoassay for the detection of pathogenic biological agents. Immuno-PCR makes it possible to detect various non-nucleic antigenic determinants in PCR by amplifying a DNA tag conjugated with a specific antibody. The registration of the results is also possible in real time as in the real-time PCR test systems. The main methodological issues in the immuno-PCR technology are: the choice of a carrier of biomolecule complexes, the choice of a method for conjugation of detection antibodies and a reporter nucleic acid, optimization of methods for amplifying signal DNA and accounting for results, and development of methods for reducing background indicators. We consider it necessary to carry out research and development work on the development and the creation of diagnostic kits based on immuno-PCR. With regard to the task of detecting small and trace amounts of antigens of pathogenic biological agents, the most likely diagnostic «niche» of the immuno-PCR method will be the detection of toxins of microbial and non-microbial origin, the minimum clinically significant dose for which is less than the sensitivity of the corresponding immunochemical test systems. Taking into account the prospects for the development of the method, in future it is possible to develop such test systems for the detection of hapten analytes, for example, some toxicants of non-biological origin

Automated real-time study of the defect-induced breakdown occurring on a film-electrode system under a high electric field.

The energy storage density of a capacitor depends on its relative permittivity and breakdown strength. Breakdown of a thin film always first occurs at weak defect spots of dielectrics under a high electric field. It is of great significance to study the defect-induced breakdown of dielectrics to improve the breakdown strength of the dielectric. The majority of studies about the defect-induced breakdown only determine a certain voltage inducing the breakdown, and the single-hole breakdown spots influence the defect-induced breakdown and the intrinsic breakdown under a high electric field, which is hard to facilitate the in-depth study of improving the breakdown strength. Herein, the self-healing breakdown techniques are applied to avoid the influence of single-hole breakdown. An automated real-time testing system is used to study the defect-induced breakdown of various complex film-electrode systems, which accomplishes the temporal and spatial localization of breakdown events according to the physical chemistry characteristics of breakdowns and intelligently displays breakdown events, and detailed classification methods of the defect-induced breakdown are discussed concisely and efficiently. This real-time testing system is effective in revealing the defect-induced breakdown of various complex film-electrode systems under a high electric field, paving the way for uncovering the breakdown mechanism and studying how to improve the capacitor's breakdown strength and energy density.

Evolution of the Oil Shale Permeability under Real-Time High-Temperature Triaxial Stress in the Jimusar Area, Xinjiang

This paper adopts a real-time high-temperature triaxial seepage test system to study the permeability evolution of oil shale in the Jimusar area, Xinjiang, with the temperature, pore pressure, and volumetric stress. The results indicate that (1) the variation process of the oil shale permeability with the temperature can be divided into three stages: slow growth stage from 20 to 350°C, rapid growth stage from 350 to 500°C with a threshold temperature of 400°C, and growth deceleration stage from 500 to 600°C. (2) With increasing pore pressure, the permeability gradually decreases. Under a volumetric stress of 17 MPa, the permeability decreases the most rapidly from 1 to 2 MPa, and under a volumetric stress of 34 MPa, the permeability decreases the fastest from 1 to 3 MPa. (3) The oil shale permeability decreases with increasing volumetric stress. At room temperature, the decrease magnitude of the permeability is small and increases with increasing temperature. The results can provide a theoretical reference for the analysis of the seepage process of thermal fluids and pyrolysis oil and gas in oil shale.