Device Synchronization Research Articles

Picometer-Sensitivity Surface Profile Measurement Using Swept-Source Phase Microscopy

In recent years, the Swept-Source Phase Microscope (SS-PM) has gained more attention due to its greater robustness to sample motion and lower signal decay with depth. However, the mechanical wavelength tuning of the swept source creates small variations in the wavenumber sampling of spectra that introduce serious phase noise. We present a software post-processing method to eliminate phase noise in SS-PM. This method does not require high-quality swept light sources or high-precision synchronization devices and achieves ~72 pm displacement sensitivity using a conventional SS-PM system. We compare the performance of this method with traditional software-based methods by measuring phase fluctuations. The phase fluctuations in the traditional software-based method are five times those of the proposed method, which means the proposed method has better sensitivity. Using this method, we reconstructed phase images of air wedges and resolution plates to demonstrate the SS-PM’s potential for high-sensitivity surface profiling measurement. Finally, we discuss the advantages of SS-PM over traditional Spectral-Domain PM techniques.

Wind conversion systems effects on power grid and ability of thyristor controlled series capacitor and static synchronous series compensator devices for dynamic performance enhancing

Wind conversion systems effects on power grid and ability of thyristor controlled series capacitor and static synchronous series compensator devices for dynamic performance enhancing

Relative intensity noise reduction for noise-like pulses based on synchronous intensity modulation

Extra-cavity synchronous intensity modulation is a straightforward and effective approach to suppress the full-bandwidth relative intensity noise (RIN) for noise-like pulse (NLP) fiber lasers. In this work, the picosecond NLPs are produced by a homemade Er/Yb co-doped mode-locked fiber laser and subsequent optimized by the synchronous intensity modulation device. The photodetector (PD) and electro-optical modulator (EOM) allow the real-time measurement and modulation for each optical pulse. A detailed description of key parameters for components is presented. The impact of DC bias voltage and RF signal amplitude on resulting RIN is experimentally investigated. We demonstrate a noteworthy reduction in RIN from 5.62% before synchronous intensity modulation to 1.91% afterward. Numerical investigations suggest that this method is potential to suppress RIN to below 1% under ideal conditions. The key factor in RIN reduction is correct operating region and high photoelectric-conversion linearity. The synchronous intensity modulation is an effective method to obtain low-RIN NLP laser sources, valuable for some practical applications.

Thermal-vibration correlation study for high-temperature superconducting maglev intelligent monitoring based on back propagation neural network analysis

The internal temperature rise inside the high-temperature superconducting (HTS) superconductor (SC) resulting from irregular magnetic field (MF) above the permanent magnet guideway is a major factor contributing to the decline of levitation performance. Real-time monitoring of the temperature rise inside YBCO SC is an important issue for the safe operation of the maglev train systems. However, the existing temperature rise testing method involves destructive intrusion less or more, easily affected by strong MF, occupying limited space and sensors prone to detachment. This paper innovatively proposes a non-contact internal temperature rise testing method combining artificial intelligence (AI) methods. Vibration is common signal of a maglev train system, which inspires to establish a fundamental thermal-dynamic levitation force synchronous testing device for YBCO SC. Then, a set of temperature rise-vibration dataset exposed to different alternating MF frequencies is created. The wavelet transform is chosen to extract the frequency band energy of vibration, and the backpropagation neural network is used to identify the corresponding temperature rise. The recognition accuracy can reach over 99.9%, which firstly proves the effectiveness of AI algorithms in the thermal-vibration correlation analysis for the HTS maglev system. The results can provide the foundation reference for the intelligent monitoring and fault diagnosis of thermal-dynamics stabilities of HTS maglev train in the future.

Enhancing Loadability of Transmission Lines Using Static Synchronous Series Compensator Devices: A Case Study of the Syrian Network

Enhancing Loadability of Transmission Lines Using Static Synchronous Series Compensator Devices: A Case Study of the Syrian Network

Real-time generation of underwater de-backscattering videos using the arrayed orthogonal polarization light source and active polarization imaging

Underwater active polarization imaging applications require mechanical rotate the analyzer to obtain orthogonal polarization state images, resulting in the inability to output the video in real time. The real-time generation of underwater de-backscattering videos using the arrayed orthogonal polarization light source and active polarization imaging method is proposed. First, the method replaces the orthogonal polarization switching position from the camera to the light source side, demonstrating that it does not affect the de-backscattering performance. Then, the arrayed orthogonal polarization light source is designed, consisting of two groups of LED lamp beads with orthogonal polarization states arranged in a staggered manner, outputting orthogonal polarization states light at different moments. The mechanical structure for polarization state switching is eliminated from the hardware, realizing an all-solid-state structure. Third, the synchronization device is designed to control the camera and the light source, realizing the acquisition of orthogonal polarization state images. Finally, the pipelined active polarization imaging method achieves real-time video output. Experimental results show the method can output the de-backscattering video in real time. The de-backscattering performance is close to the mechanical active polarization imaging, and the deviation degrees are less than 7%. The method has the advantages of easy implementation, high real-time performance, unaffected frame rate of the output video, and unlimited camera sensors.

A communication-less islanding detection scheme for hybrid distributed generation systems using recurrent neural network

The proposed scheme in this research paper is a communication-less islanding detection system based on recurrent neural network (RNN) for hybrid distributed generator (DG) systems that include both synchronous and inverter-based DG devices. The scheme consists of three stages: time-domain feature extraction (FE) from the three-phase voltage signal at the point of common coupling (PCC), feature selection using the wrapper method, and detection using a long short-term memory (LSTM) RNN algorithm. To assess the performance of the proposed scheme, a comprehensive set of islanding and grid-connected scenarios was created using the IEC 61850-7-420 test system in MATLAB/Simulink. After feature extraction in MATLAB, the feature selection and LSTM model training/testing steps were conducted in Python. Thirteen features were extracted from the voltage signal, and the most significant features were selected for detection using the wrapper method. The detection process encompassed various events, such as line faults, load switching, and capacitor switching, occurring in both islanded and grid-connected modes. The proposed scheme was compared against existing techniques, artificial neural networks, and support vector machines under the same conditions. The proposed scheme demonstrated excellent accuracy (99.68 %), selectivity (99.44 %), and sensitivity (100 %) under normal conditions with all features. It also performed well in noisy environments, with accuracies of 98.94 % and 97.04 % with 40 dB and 30 dB noise, respectively. This research highlights the importance of quality and quantity of data for training intelligent RNN-based IDSs and demonstrates the effectiveness of the proposed scheme in detecting islanding in hybrid DG systems.

Time Synchronization Based on Cross-Technology Communication for IoT Networks

Time synchronization is a fundamental requirement for wireless communication systems to work properly. Most of the existing studies focus on time synchronization among homogeneous devices. This work investigates time synchronization with heterogeneous technologies (e.g., WiFi, ZigBee and Bluetooth) which is important for the rising Internet of Thing (IoT) scenarios where heterogeneous devices coexist. Recent advances in Cross-Technology Communication (CTC) break the wall between heterogeneous wireless devices. In this work, we propose a new time synchronization strategy based on the CTC technique and provide a technique called TimeBee, which takes the advantage of coordination from a WiFi device to assist ZigBee devices for time synchronization. An effective method is employed so that ZigBee nodes are coordinated for time synchronization based on the received timestamps from WiFi devices. The experimental results show that TimeBee achieves global time synchronization with low time errors.

Development of the automatic system for switching on the generating equipment for parallel operation with the electric power system

RELEVANCE. Synchronization is an algorithm of actions to switch on synchronous generators for parallel operation with the power system and is an integral part of the power generation process. In practice, the process of synchronization involves some difficulties. The developed automatic synchronization device is digital and is integrated into the microprocessor terminal of the CPA-M complex, allowing to solve the arising problems by means of synchronization using different methods, including the developed method of accelerated synchronization.THE PURPOSE. Create a comprehensive automated synchronization system based on the CPA-M microprocessor terminal (manufactured by a Novosibirsk company) with a variability of methods. Analyze existing synchronization devices, synthesize traditional synchronization methods, create a non-traditional intermediate method on their basis and integrate it into the automated system. Develop algorithms for the measuring and logical units, as well as for the synchronization system output unit. Experimental testing of algorithms by feeding real signals from voltage sensors on a physical model with a rotating synchronous machine (12 kW generator under test).METHODS. The problem of research studied using theoretical and practical approaches. Theoretical methods - analysis, synthesis and classification. Practical methods - modeling in MatLab® environment, comparison, experiment, observation.RESULTS. The paper describes the architecture, construction principles, settings selection of the synchronization system, as well as the interaction of its logical part with adjacent units (measuring unit, output unit). The work gives a comprehensive description of the system setup and integration of its measuring and logic parts into the CPA-M microprocessor terminal with a test on a physical object.CONCLUSION. The system has extended functionality compared to analogs, allowing the use of traditional methods and the developed method of accelerated synchronization. The results predict reduction of capital costs for automation systems, as one device provides synchronization on several circuit breakers and reduction of generator operation costs, as using this system, machine parts exposed to unacceptable thermal and mechanical effects. The development is relevant for the elimination of emergencies in the power system and reducing thermal and dynamic impacts on the generator. The social importance of the project is the exclusion of the human factor. The prospect of using the development - in the educational process of the university and at real power facilities, in particular on large synchronous generators.

High-speed chaos-based secure optical communications over 130-km multi-core fiber.

Chaotic optical communication is of great significance for secure data transmission. Despite rapid development over the decades, high-speed (>100 Gbps) and long-distance (>100 km) chaotic optical communication in a single fiber is still full of challenges. Here, we propose and experimentally demonstrate high-speed and long-distance chaos-based secure optical communications using mutual injection of semiconductor lasers and space-division multiplexing (SDM) techniques. The encrypted signals are transmitted through all seven core channels of the multi-core fiber (MCF), which effectively expands the aggregate transmission capacity of a single fiber. A pair of source and synchronization devices based on mutual injection of semiconductor lasers are employed to effectively encrypt and decrypt signals. Chaos-based secure optical communications with 70-Gbps on-off keying (OOK) and 140-Gbps quadrature phase-shift keying (QPSK) signals over a 130-km MCF are successfully demonstrated in the experiment with favorable performance. The demonstration may pave the way for future ultrahigh capacity and ultra-long distance chaotic optical communications by fully exploiting multi-dimensional resources of light waves, including the spatial dimension.

ОСОБЛИВОСТІ ВИКОРИСТАННЯ АЛГОРИТМІЧНОГО СПОСОБУ РЕЗЕРВУВАННЯ PRC ПРИ МОДЕРНІЗАЦІЇ КОМПЛЕКСУ ПЕРВИННИХ ПРИСТРОЇВ СИНХРОНІЗАЦІЇ

In modern synchronization networks, PRC primary synchronization devices have become an integral component necessary to ensure stable operation and long-term accuracy of reference signals. But their high cost and insufficient use to provide only one unit lead to the need to find other options. Frequency standard manufacturers supply PRS as dedicated hardware without redundancy, whereas in modern synchronization networks PRS must be redundant in order to maintain the required quality of the reference signals. The paper considers the possibilities of modernization of the complex of primary devices of the synchronization network using the example of PJSC “Ukrtelecom” and analyzes the features of using the BesTime algorithm. The main advantages of the protocol in ensuring stable and high-quality operation of the synchronization network are considered. The basic principle of operation of the BesTime algorithm is described, as an algorithmic method of PRC reservation during modernization, the basis of the algorithm is the “triangular hat” method, and as a result, the resulting signal with the best characteristics of one of the three nodes is obtained according to the algorithm. It is demonstrated how the use of the algorithm makes it possible to divide a complex network of synchronization channels into simple and well-controlled fragments with equally high quality reference signals.

Difference analysis of musculation and estimation of sEMG-to-force in process of increasing force and decreasing force

The movement of the human limb is driven by muscle contraction. Surface electromyography (sEMG) is a weak bioelectric activity generated during muscle contraction, which reflects information regarding muscle activation. The increasing force and the decreasing force are reverse processes. Investigating the difference in musculation between the two processes and establishing an input–output model between sEMG and force can clarify the biodynamics mechanism of the human body. In the study, we try to find the truth about the difference in musculation using sEMG signal in the process of increasing and decreasing force, and create a model of the relationship between sEMG and force. A synchronous data acquisition device is used to collect force and sEMG signals, including the raw sEMG signal and its envelope signal. A new method for extracting the feature of the sEMG signal based on the spectrogram is introduced. Up to sixteen features are extracted from the sEMG signal, and their performances are evaluated. The experimental results indicate that sliding mean filtering can significantly improve feature performance. A processing means of isometric force and sEMG feature is proposed. Difference in musculation about force-increasing and force-decreasing is detailedly analyzed by statistical T-test. We come to the conclusion that the sEMG signal evoked via musculation is not exactly the same in the two processes, with a more significant difference when the muscle contraction strength is weaker, and a less significant difference when the muscle contraction strength is stronger. Finally, five regression models are used for sEMG-to-force estimation, and their performances are compared separately. The experimental results show that the DNN exhibits the best performance, achieving a RMSE of 12.782 and a R2 of 0.911.

Physical Simulation Test of Underground Coal Gasification Cavity Evolution in the Horizontal Segment of U-Shaped Well

A key point in the underground coal gasification process is the cavity evolution in the horizontal segment. The morphological evolution law of the gasification cavity has not been clarified, which is the bottleneck restricting the analysis of its controllability. In this paper, a physical simulation system for cavity generation was developed, and the cavity evolution in a targeted coal seam with overburden pressure was duplicated in the laboratory. A set of temperature field synchronous monitoring devices was developed to realize temperature sampling within a cavity and the surrounding rock. By analyzing the relationship between the overall temperature distribution pattern and the gasification agent injection condition, the morphological propagation law of the cavity is verified to be water drop-shaped, and influencing factors including the injection flow rate and the gasification agent component ratio are investigated. The axial length and volume of the cavity increase with an increasing injection flow rate. Higher oxygen content results in increased size in all dimensions. The research results provide theoretical support and reference for applying controlled cavity formation in the horizontal segment of U-shaped wells.

Impact of oestrus synchronization devices on ewes vaginal microbiota and artificial insemination outcome.

The low pregnancy rate by artificial insemination in sheep represents a fundamental challenge for breeding programs. In this species, oestrus synchronization is carried out by manipulating hormonal regimens through the insertion of progestogen intravaginal devices. This reproductive strategy may alter the vaginal microbiota affecting the artificial insemination outcome. In this study, we analyzed the vaginal microbiome of 94 vaginal swabs collected from 47 ewes with alternative treatments applied to the progesterone-releasing intravaginal devices (probiotic, maltodextrin, antibiotic and control), in two sample periods (before placing and after removing the devices). To our knowledge, this is the first study using nanopore-based metagenome sequencing for vaginal microbiome characterization in livestock. Our results revealed a significant lower abundance of the genera Oenococcus (Firmicutes) and Neisseria (Proteobacteria) in pregnant compared to non-pregnant ewes. We also detected a significant lower abundance of Campylobacter in the group of samples treated with the probiotic. Although the use of probiotics represents a promising practice to improve insemination results, the election of the suitable species and concentration requires further investigation. In addition, the use of progestogen in the synchronization devices seemed to increase the alpha-diversity and decrease the abundance of harmful microorganisms belonging to Gammaproteobacteria and Fusobacteriia classes, suggesting a beneficial effect of their use.

Bright and spectrally stable pure-red CsPb(Br/I)3 quantum dot LEDs realized by synchronous device structure and ligand engineering

All-inorganic CsPbBrxI3−x perovskite quantum dots (PQDs) show great potential for pure-red light-emitting diodes (LEDs). However, spectral instability caused by ion migration at high electric fields and lower luminance limit its practical applications. Here, the ITO/ZnO/PEI/CsPbBrxI3−x PQDs/N, N, N-tris (4-(9-carbazolyl) phenyl) amine (TCTA) (3 nm)/1-bis [4-[N, N-di(4-tolyl)amino]-phenyl]-cyclohexane (TAPC)/MoO3/Au device structure is first designed to reduce the overall operating voltage of the device by enhancing hole injection and transport, effectively avoiding ion migration under high electric fields, and then by post-treating CsPbBrxI3−x PQDs with n-octylphosphonic acid: K to remove surface defects and increase the activation energy of halogen migration, further suppressing ion migration while improving the optical properties of the material. Ultimately, the color-stable pure-red perovskite LED achieved a high luminance of 13730 cd m−2 at voltages as low as 4.9 V and a maximum EQE of 16.7%.

EVALUATION OF THE VALUE OF EQUIVALENT ENERGY LOSSES DUE TO THE QUALITY OF FREQUENCY SYNTHESIS FUNCTIONING IN DIGITAL COMMUNICATION SYSTEMS WITH QUASI-COHERENT RECEPTION OF SIGNALS WITH QUADRATURE AMPLITUDE KEYPAD

Useful transmitted information when using digital transmission systems with quadrature amplitude shift keying lies in the change in the amplitude and phase of the signal. This circumstance causes significantly higher requirements for the magnitude of destabilizing factors, namely the phase noise of signal packages at the input of the demodulating device of signals with quadrature amplitude keying, which affect the useful signal, resulting in a decrease in the reliability of reception. In this article, we restrict ourselves to considering the requirements for short-term frequency stability of synthesizers of digital transmission lines, which use signals of multi-position quadrature-amplitude keying in conjunction with quasi-coherent reception. The carrier wave is extracted on the receiving side directly with the help of a carrier recovery device from the received QAM signal by demodulating it, followed by narrow-band filtering. The phase-locked loop in this case functions as a narrow-band tunable filter for extracting the carrier wave. An increase in the quality of demodulation and signal filtering processes leads to a decrease in the phase fluctuation of the restored carrier, a decrease in the level of additive noise, and a decrease in the magnitude of energy losses when using quasi-coherent reception compared to the ideal one, which requires the complete absence of a phase error of the selected reference signal. Such an approximation of the noise immunity of real coherent QAM demodulators to the theoretical one limits the phase noise of the signal at the demodulator input, which is associated with the non-ideal operation of frequency synthesizers on the transmitting and receiving sides of digital communication lines. The research methods used in the article are based on the theories of potential noise immunity, demodulator synchronization, and phase locked loop systems. For the carrier recovery device, the noise band value was chosen in the range from to (where T – is the symbol duration), since with the indicated ratios, the distribution law of the phase error can be considered normal. It was assumed in the work that the devices for automatic gain control and clock synchronization in the radio receiving system function ideally, and the frequency response of the channel corresponds to the Nyquist condition.

Collaborative Domain Adaptation Network for Partial Discharge Source Localization in Gas-Insulated Switchgear

Abnormal discharge in gas-insulated switchgear (GIS) is a key cause of insulation failure, and it is also an external manifestation of insulation defects. Sensitive discharge source localization is an important goal of GIS partial discharge (PD) monitoring. However, most existing GIS PD source localization methods rely on time-delay estimation, which not only requires a high-precision synchronous sampling device but also suffers from serious interference. To this end, a collaborative domain adaptation network (CDAN) is proposed for GIS PD source localization. First, a synchronous squeezing wavelet transform is introduced to filter out the noise, eliminating the influence of noise on GIS PD source localization. Then, one-dimensional attention convolutional neural network is constructed to ensure that discriminative temporal fine-grained information is extracted. Next, a CDAN is proposed to transfer the localization knowledge learned from the simulation to actual GIS and achieve high-precision localization through domain matching and alignment. The results demonstrate that the error of the CDAN proposed is only 19.87 cm, which is considerably better than that from other methods. This work provides a reference solution for GIS PD source localization.

Pilot protection for active distribution networks based on the phase-space trajectory of quasi-power

Current differential protection (CDP) is introduced into active distribution networks (ADNs) to improve the protection reliability. However, the complex fault characteristics of ADNs lead to degradation of the CDP performance. In addition, it is difficult for CDP to satisfy the requirements of various scenarios for protection. Under this context, this study proposes a pilot protection method based on the phase-space trajectory of quasi-power (PSTQP). First, the feasibility of the quasi-power theorem to be used in ADNs is analyzed. Second, the quasi-power is selected as the one-dimensional time series for phase-space reconstruction, and the characteristics of the PSTQP under internal and external faults are analyzed. Finally, two protection criteria are designed according to the requirements of different protection scenarios. The PSCAD/EMTDC-based simulation results verify that the designed protection criteria are effective for various fault conditions. Furthermore, the high-speed protection scheme can shorten the fault duration, and the protection scheme for immune to synchronization errors can reduce dependence on data synchronization and eliminate the requirement for additional synchronization devices.

Research on Improvement of Synchronous Tensioning Device of Belt Conveyor

Under complex working conditions in the mines, the belt conveyor’s tensioning device is prone to uneven tension. Given this problem, the error of the shunt of synchronous motors is analyzed, and a synchronous tensioning device with double cylinders is designed by using a synchronous motor and a PID controller. Simulation analysis is carried out to verify the rationality and effectiveness of the optimization design. It can provide a corresponding reference for the design and use of the belt conveyor synchronous tensioner system.

Inertia Estimation of Synchronous Devices: Review of Available Techniques and Comparative Assessment of Conventional Measurement-Based Approaches

The increasing deployment of renewable energy sources (RESs) reduces the inertia levels of modern power systems, raising frequency stability issues. Therefore, it becomes crucial, for power-system operators, to monitor system inertia, in order to activate proper preventive remedial actions in a timely way, ensuring, this way, the reliable and secure operation of the power system. This paper presents a brief review of available techniques for inertia estimation of synchronous devices. Additionally, a comparative assessment of conventional measurement-based inertia-estimation techniques is performed. In particular, five conventional inertia-estimation techniques are considered and examined. The distinct features of each method are presented and discussed. The effect of several parameters on the accuracy of the examined methods is evaluated via Monte Carlo analysis. The performance of the examined methods is evaluated using dynamic responses, obtained via RMS simulations, conducted on the IEEE 9 bus test system. Based on the conducted analysis, recommendations to enhance the accuracy of the examined techniques are proposed.