Synchronous Operation Research Articles

Operation twins: production-intralogistics synchronisation in Industry 4.0

ABSTRACT The widespread adoption of Industry 4.0 technologies is revolutionising how manufacturing operations are managed and done. This revolution drives manufacturing practitioners to reevaluate their current manufacturing planning and control (MPC) strategies to maintain global competitiveness. The production and intralogistics (PiL) operations within traditional MPC systems are organised separately, which results in inferior overall solutions. PiL operations in a single factory are inherently coupled and interact with each other throughout the entire process, which needs synchronous organisation and operations. This paper introduces a novel concept of operations twins (OT), with vertical twinning and horizontal twining, for achieving PiL synchronisation by leveraging Industry 4.0 technologies and innovative operations management strategies. An Internet-of-Things (IoT)-based vertical twinning method is developed for real-time object-level data collection and information-sharing between PiL. A horizontal twinning mechanism is proposed to support real-time coordination of production and intralogistics operations with real-time information-sharing. A numerical study is carried out, and the results show that OT outperforms the widely used static and dynamic methods regarding the overall stability and typical measures such as makespan, average manufacturing time, and average tardiness under different levels of uncertainties.

Cascade hydropower stations short-term operation for load distribution considering water level synchronous variation

The load distribution of cascade hydropower stations is associated with the safe operation of the hydropower stations and power grids. The conventional load distribution of cascade hydropower stations does not consider the synchronous operation of the water level. The inconsistent water level variation process of cascade hydropower stations is not conducive to the safe operation of hydropower stations and power grids. Therefore, the main purpose of this paper is to introduce the concept of equal reservoir full storage rate (ERFSR) to guide the load distribution of cascade hydropower stations. In addition, hydropower is used for new energy consumption considering the advantages of the rapid start-stop in hydropower units. The load distribution model of cascade hydropower stations is established, and three cases are set to verify the universality of the proposed model in the upper reaches of the Yellow River. The results show that (1) The concept of ERFSR can effectively guide load distribution and realize water level synchronization of cascade hydropower stations. (2) The output process of each hydropower station can be basically consistent with the load process to achieve synchronous peak shaving. (3) New energy consumption has little effect on the daily water consumption of downstream cascade hydropower stations.

Optimal pulse width modulation for permanent magnet synchronous motor drive with improved torque and thermal losses using pulse numbers

This paper utilises the concept of pulse numbers to provide a new optimal pulse width modulation strategy for permanent magnet synchronous motor operation. The benefits of traditional modulation systems are preserved, as is an improvement in torque and thermal loss reduction. The continuous modulation approaches' performance limitations are solved by separating the performance constraints based on the drives surface area. The rotating component, which is regulated through odd and even pulse numbers, is used to mimic torque and thermal losses. With increases to 20 rpm and 30 rpm speeds, the suggested methods boost the 6% to 8% line current. Thermal losses are reduced by 21° C to 23° C, and torque is improved by 2 to 4 Nm. The proposed system is implemented by creating a MATLAB model that ensures the theoretic concept.

A New Perspective for Relating Virtual Inertia With Wideband Oscillation of Voltage in Low-Inertia DC Microgrid

Virtual synchronous generator (VSG) has been a grid-friendly integration control technique for the integration of grid-connected inverters. However, the emulated inertia and damping of VSG control technique can also be used in the field of dc systems. In this article, a virtual synchronous control is proposed to dampen the wideband oscillation of dc voltage in a dc microgrid. The proposed control strategy contributes to maintaining the synchronous operation of dc converter with the network. Besides, the relationships among damping, inertia, wideband oscillation, rate of change of voltage (RoCoV) as well as DC voltage nadir (DCVN) are studied. It is concluded that the RoCoV and DCVN are similar as the oscillation frequency and fluctuation ranges of poorly-damped oscillation, respectively. A unified concept is proposed by connecting the oscillation-related stability with the inertial transient response originated from the imbalanced powers/mismatched currents. Besides this, the inertia plays the same role as damping because the inertia contributes to maintaining the original state and damping to impeding further change. A new feedback analytical method is proposed to clarify the important role of RoCoV and DCVN on the motion of dc voltage. Finally, the theoretical results are compared with simulations and experiments.

Using a static naming approach to implement remote scope promotion

GPUs employ simple coherence mechanisms and require explicit use of costly synchronization operations for data integrity. Local-scoped synchronization can be utilized to lower the performance penalty of synchronization when sharing is within a subgroup of threads. Unfortunately, in asymmetric sharing (which is an important dynamic sharing pattern), it is necessary to use global-scoped synchronization due to possible accesses by remote sharers. Remote Scope Promotion (RSP) was introduced to take advantage of local-scoped synchronization at regular accesses while using scope promotion at occasional remote accesses. First implementation of RSP makes use of a simple approach that performs costly cache operations on all L1 data caches when implementing scope promotion, and therefore, it performs poorly on large scale GPU systems. We present nRSP which utilizes a static naming mechanism to identify regularly accessing agent in asymmetric sharing and avoids applying costly coherence actions on every L1 data cache when implementing scope promotion. We evaluate nRSP using timing detailed Gem5-APU simulator modeling a GPU system with 128 Compute Units and show that nRSP lowers remote synchronization overhead greatly and improves performance considerably. On average, nRSP provides around 28% speedup on a 128 Compute Unit GPU device.

Application of electromagnetic continuous variable transmission in hydraulic turbines to increase stability of an off-grid power system

In the context of climate change, today's adoption of renewable energy sources in isolated power systems is becoming an increasingly more significant issue. Micro-hydro power plants are emerging as a mature balancing technology and a great alternative to large hydropower plants as they do not encounter population displacement and many environmental problems. It is worth noting that hydroelectric power plants combined with various sources require improvement in control laws and algorithms. Strong disturbing impacts, namely transient processes, in an isolated electric power system cause an appreciable decrease in dynamic stability. This paper presents research conducted to ensure synchronous parallel operation of permanent-magnet generators used in micro-hydroelectric power plants in an isolated power system with a controllable flexible coupling between turbine and generator. The importance of this study lies in the issue of electromechanical compatibility to be achieved in parallel operation of generators that have different parameters of time constant of mechanical inertia of rotors of electrical machines. This paper provides an overview of possible solutions to the identified problem. A concept based on a controllable flexible coupling between generator and turbine is proposed as a promising avenue to solve this problem. The mathematical models are presented along with the laws and algorithms developed for automatic control of the generator speed. Oscillograms of simulation and physical modeling presented in the final part of the paper show parallel operation of permanent-magnet synchronous generators in an isolated electric power system for various electrical distances of three-phase short circuit points.

Studies on of phase error oscillations in a class of third-order optical phase locked loop and its effect on a slave optical phase locked loop

Dynamics of a third-order optical phase locked loop (OPLL) with a resonant type loop filter (LF) has been studied analytically and numerically. The range of stable synchronous operating zone of such OPLL has been estimated analytically in system and signal parameters and obtained predictions are in good agreement with numerical results. Beyond the stable region, it is found that chaotic oscillation of phase error occurs through a sequence of period doubling bifurcation. In addition to this, tracking of such periodic as well as chaotic dynamics of third-order OPLL by another OPLL in master-slave configuration has also been explored here. The tracking is possible by slave OPLL within a very short range of effective frequency offset by keeping other design parameters within the stable mode of operation. The synchronization of the master and slave OPLLs has been studied in generalized sense by considering auxiliary system. The study is very important and helpful for optical signal processing and also in chaos-based secure communication.

Оцінка параметрів оптимізованого покриття графіків навантажень в режимах синхронної роботи енергосистем України та Польщі для характерних діб на прикладі фактичних значень встановленої потужності та графіків навантаження

A mathematical model is proposed for optimizing the modes of using the generating capacities of the national energy system in the conditions of competition and interstate agreements and requirements, which has the advantages of adequately modeling the modes of using hydroelectric units and power units, for the mode of synchronous operation of the power systems of Ukraine and Poland for characteristic days, using the example of actual values of installed capacity and load schedules. The model belongs to the class of optimization problems with the criterion of minimizing the costs of production and import of electricity. It is implemented in the SolverStudio optimization package in the MathProg algebraic modeling language using the COIN-OR PuLP modeling language. The use of the model made it possible to explore the possibilities of optimized dispatching of generating capacities, as well as reserve capacities of large-capacity storages, the limits of permissible values for the parameters of generating and storage capacities, and cross-border flows, in which stable balanced operation of the unified energy system is possible. Model calculations of the parameters that provide optimized coverage of load curves for a typical day are performed using the example of actual values of installed capacity and load curves in 2018. The specific features accounting of the operation of generating, reserve and storage capacities of power systems in the model made it possible to determine and explore the possibilities of optimized dispatching of the components, the boundaries of permissible values of the parameters of generating and storage capacities, under which stable balanced operation of energy systems in synchronous operation modes is possible. The simulation results can be applied in the tasks of forming predictive balances for covering daily schedules of electrical loads to study the prospects for short- and long-term development of storage and generating capacities, the optimal achievable volumes of cross-border electricity flows between the energy systems of Ukraine and neighboring countries included in ENTSO-E, which is relevant in conditions of connection to these power systems. Keywords: load schedules, modes of synchronous operation of power systems of Ukraine and Poland

Truck and Unmanned Vehicle Routing Problem with Time Windows: A Satellite Synchronization Perspective

We consider an important feature of satellite synchronization in the practical scenario of using unmanned vehicles (UVs) carried by trucks for “last-meter” delivery and introduce the truck and UV routing problem with time windows (TUVRP-TW) for optimizing the routes of a homogeneous fleet of truck-UV combinations. A UV that has been dispatched from its truck must be picked up by the same truck or must return by itself to the depot. Customers with time windows are classified into two types: truck-UV customers (TUCs) and UV customers (UCs). The TUCs where trucks dispatch or pick up the carried UVs are regarded as satellites. Fleet coordination and satellite synchronization are essential for modelling the TUVRP-TW. We classify satellite synchronization into inner-satellite synchronization and intersatellite synchronization. The inner-satellite synchronization generally considered in the literature focuses on synchronization operations at the same satellite. Intersatellite synchronization, which focuses on synchronization operations at various satellites, allows UVs to not return to the dispatched locations, if necessary. In the mixed-integer linear programming model of the TUVRP-TW, both binary variables for identifying the appointed satellites and continuous variables for time continuity constraints are introduced to ensure the interaction between truck routes and UV routes. A hybrid algorithm based on a greedy randomized adaptive search procedure (GRASP) and a variable neighborhood search (VNS) is provided. Based on generated instances and benchmark instances, computational experiments are conducted to evaluate the performance of the intersatellite synchronization, the performance of the developed formulation, and the applicability of the hybrid algorithm.

Adaptive Positioning Control of Servomotor Based on Model Identification

The new energy vehicle industry needs a large number of vehicle power batteries, and its production depends on high-speed and high-precision battery pole-piece cutting equipment, which is mainly composed of the electrode material roll uncoiling unit, buffering unit, main drive unit, and cutting unit. Due to the nonlinearity and high-speed intermittent motion mode of a servomotor, the existing control technology is difficult to apply to the cutting system. This article presents a multimotor linear velocity planning approach used to ensure synchronous and cooperative operation of the motors in the cutting system. To achieve fast and accurate positioning control of the main drive motor running in fast acceleration and deceleration, periodic and intermittent mode, an adaptive position controller based on data-driven modeling technique is proposed, which makes the parameters of the controller change with the operation state of the main drive motor so that the controller can obtain good positioning accuracy in a wide working range of the main drive motor. Two linear models are established to represent the relationship between the positioning error and the positioning controller parameters and the main drive motor running conditions. The parameters of the two models are estimated offline and the parameters of the adaptive position controller can be obtained online quickly. Thus, the proposed control method for the main drive motor can be easily realized by general PLC in practical application. Simulation study results show that using the proposed method, the positioning error of the main drive motor is less than 0.1 mm when cutting 89-mm-long battery pole-piece and cutting 1 to 3 pieces/s. This result is much better than that of the position controller with fixed parameters.

Load Balancing and Parallel Computation Model for Performance and Accuracy over the Cluster of Nodes

Cloud computing can be online based network engineering which contributed with a rapid advancement at the progress of communication technological innovation by supplying assistance to clients of assorted conditions with aid from online computing sources. It's terms of hardware and software apps together side software growth testing and platforms applications because tools. Large-scale heterogeneous distributed computing surroundings give the assurance of usage of a huge quantity of computing tools in a comparatively low price. As a way to lessen the software development and setup onto such complicated surroundings, high speed parallel programming languages exist which have to be encouraged by complex operating techniques. There are numerous advantages for consumers in terms of cost and flexibility that come with Cloud computing anticipated uptake. Building on well-established research in Internet solutions, networks and utility computing, virtualization et cetera Service-Oriented Architectures and the Internet of Services (IoS) have implications for a wide range of technological issues such as parallel computing and load balancing as well as high availability and scalability. Effective load balancing methods are essential to solving these issues. Adaptive task load model is the name of the method we suggest in our article for balancing the workload (ATLM). We developed an adaptive parallel distributed computing paradigm as a result of this (ADPM). While still maintaining the model's integrity, ADPM employs a more flexible synchronization approach to cut down on the amount of time synchronous operations use. As well as the ATLM load balancing technique, which solves the straggler issue caused by the performance disparity between nodes, ADPM also applies it to ensure model correctness. The results indicate that combining ADPM and ATLM improves training efficiency without compromising model correctness.

Out‐of‐step detection of synchronous generators using dual computational techniques based on correlation and instantaneous powers

To maintain synchronous operation of interconnected systems, it is necessary to keep balance between power generation and consumption. Faults may result in large oscillations in power flows and loss-of-synchronism between one generator and the rest of the power system. A correlation coefficient is a useful statistic that can be used to detect voltage, frequency or angular instabilities, and to determine an asynchronous process. Hence, it is a smart technique to predict the out-of-step event following fault situations. In this paper, the technique based on the auto/cross-correlation and instantaneous powers is presented to identify sudden disturbances of various electrical signals in the case of asynchronous operation. To validate the method performance, a power network with real parameters is simulated on Alternative Transient Program (ATP) platform, and the algorithm is implemented in MATLAB software. Simulation studies reveal that the proposed scheme is able to detect the out-of-step conditions upon which the relay issues a trip signal, yet remains inactive under normal synchronized operating conditions. Thus, the out-of-step is declared before the second pole slipping occurs, and an instability time can be accurately assessed. Moreover, it can develop novel quadrilateral operating characteristics to discriminate between the synchronous and asynchronous operation of the AC generator.

Power Quality and Low Voltage Ride Through Capability Enhancement in Wind Energy System Using Unified Power Quality Conditioner (UPQC)

The various approaches used to improve the Low Voltage Ride Through (LVRT) capabilities of DFIG-based wind turbine systems are investigated in this study (WT). The Type-III WT machine, which is primarily based on DFIG, is connected to the grid without a digital power interface, resulting in unmanageable terminal voltage or reactive electricity output. As a consequence, novel LVRT approaches based on the deployment of additional active interface technologies were given in this work. The problem of low voltage faults is now being addressed using a variety of approaches. By analyzing LVRT approaches for DFIG-based WECS, this research attempts to discover such working ways by bridging the gap in terms of overall adaptive performance, operative complexity of controllers, and cost-effectiveness. This study suggests ways to improve LVRT's ability to rely on the relationship arrangement in three major areas based on their grid integrations. The wind turbine system is connected to a DVR, STATCOM, and UPQC in this study for active and reactive power regulation throughout the fault detection procedure. Using UPQC with SRF theory offers improved reaction during faults to increase active power and maximum compensation in reactive power with synchronous reference frame and without synchronous reference frame operation presented in this paper.

Transient switching dynamics between asynchronous and synchronous modes in a bidirectional ultrafast fiber laser

Continuous interest in bidirectional ultrafast fiber lasers not only reinforces the practical applications in coherent dual-comb spectroscopy but also enriches the understanding of soliton dynamics in nonlinear systems. However, the transient dynamics of bidirectional solitons are still unexplored. Here, we report on an observation of the switching dynamics in a net-anomalous-dispersion bidirectional ultrafast fiber laser which can operate in both asynchronous and synchronous operations. Transient switching dynamics between the asynchronous and synchronous states are demonstrated, which is accompanied by switchable and weak interaction between bidirectional solitons. The dynamical evolution and output properties of the asynchronous and synchronous bidirectional solitons are investigated respectively. Stable breathing solitons in the synchronous operation show opposite behaviors in both spectra and pulse energy dynamics, which vary with different pump powers. Our findings provide insight into the transient dynamics in ultrafast lasers and contribute to the understanding of nonlinear systems in general.

Synchronization behaviors of a vibrating mechanical system with adjustable frequencies and motion trajectories

In present work, the double and triple-frequency synchronization behaviors of a vibrating mechanical system with two different driving frequencies, driven by three reversed rotating exciters, are investigated by theory, numeric, and experiment. Based on Lagrange’s equations, the dynamic model corresponding to vibrating machine is proposed and motion differential equations are constructed. The Bogoliubov standard formal equations for three exciters are established, by introducing the asymptotic method, in which the synchronization problem is converted into that of the existence and stability of zero-valued solution of the average differential equations. The synchronization criterion of satisfying the synchronous operation is deduced. According to the Routh–Hurwitz criterion, the stability criterion of the synchronous states is achieved analytically. Based on the obtained theory results, the stability characteristics of the system, are numerically discussed in detail, including the stability ability coefficients and stable phase differences. Finally, simulations and experiments under the condition of two different driving frequencies, are performed to further examine the validity of the theoretical and numerical qualitative results. The present work can provide a theoretical reference for designing some new types of the vibrating machines with adjustable frequencies and motion trajectories.

Innovative design of automatic demoulding device for lightweight wall panels

Abstract The automatic production of lightweight wallboard is an important support for promoting the development of the construction industry. In view of the problems of low efficiency and large demoulding loss in the production process, an innovative improvement of the demoulding device for lightweight wallboard is proposed. Optimizing the demoulding device for lightweight wall panels by combining a gripping device and a conveying device. The synchronous operation of demoulding of wall panel and mold recovery is realized. For the intermittent transmission of wallboard production, it is proposed to use 51 single-chip microcomputer as the main control chip, and S-curve acceleration and deceleration as the speed control algorithm. The demolding production efficiency of the device is improved, and the demolding loss is reduced. The feasibility and effectiveness of the innovative design of the lightweight wallboard stripping device were verified by finite element analysis of the grabbing device.

A Cooperative Shared Control Scheme Based on Intention Recognition for Flexible Assembly Manufacturing.

Human–robot collaboration (HRC) has been widely utilized in industrial manufacturing and requires a human to cooperate with a robot at the same workspace. However, as HRC focuses on workspace sharing along with independent work, it is not a real collaboration between a human and a robot and, thus, cannot guarantee a smooth cooperation and synchronous operation. To this end, a cooperative shared control scheme based on intention recognition is proposed in this study by sharing workspace and time. In the proposed method, a classification algorithm based on three-dimensional (3D) point cloud is utilized to recognize the human operation intention. Then, the robot can select a suitable tool to match the human's operation. A robot motion control algorithm is developed to detect the obstacles in the HRC process. A cooperative control strategy is introduced to achieve synchronous operation. A simple assembly task is also performed to demonstrate the proposed scheme's effectiveness. The proposed HRC method with shared control can be extended to more complicated and delicate flexible tasks in assembly manufacturing.

Development and application of the 3000 m-level multiparameter CPTu in-situ integrated test system

Accurate knowledge of the mechanical properties of deep-sea sediments and various parameters of the seafloor environment is extremely important for deep-sea geological investigations. In this paper, a set of self-developed 3000 m-level multiparameter CPTu in-situ integrated test system is developed, which successfully solves the technical problems existing in deep-sea CPTu detection technology, hydraulic fine control penetration technology, coaxial cable and optical cable composite transmission technology, etc. A multi-functional integrated probe rod is successfully developed, which contains 3000 m-level CPTu detection technology, single rod 3 D four-way stereo resistivity measurement technology, sediment geochemical environment multiparameter puncture detection technology, and rapid detection of seafloor sediment temperature gradient technology, which can simultaneously obtain in-situ physical and mechanical properties of sediments and various geochemical indicators. It can realize the synchronous operation of static penetration of deep-sea integrated probe rod, static sampling of surface sediment and undersea camera, which breaks the limitation of single parameter and ensures the authenticity and validity of data. At present, the equipment has been successfully sea-tested in the Shenhu Sea Area of the South China Sea and obtained better data feedback, which can provide guidance and technical support for deep-sea mining, gas hydrate mining, deep-sea exploration and other operations.

A subcycling/non-subcycling time advancement scheme-based DLM immersed boundary method framework for solving single and multiphase fluid–structure interaction problems on dynamically adaptive grids

In this paper, we present an adaptive implementation of the distributed Lagrange multiplier (DLM) immersed boundary (IB) method on multilevel collocated grids for solving single- and multiphase fluid–structure interaction (FSI) problems. Both a non-subcycling time advancement scheme and a subcycling time advancement scheme, which are applied to time-march the composite grid variables on a level-by-level basis, are presented; these schemes use the same time step size and a different time step size, respectively, on different levels. This is in contrast to the existing adaptive versions of the IB method in the literature, in which coarse- and fine-level variables are simultaneously solved and advanced in a coupled fashion. A force-averaging technique and a series of synchronization operations are constructed to achieve excellent momentum and mass conservation across multiple levels of grid hierarchy. We demonstrate the versatility of the present multilevel framework by simulating problems with various types of kinematic constraints imposed by structures on fluids, such as imposing a prescribed motion, free motion, and time-evolving shape of a solid body. The DLM method is also coupled to a robust level set method-based two-phase fluid solver to simulate challenging multiphase flow problems, including wave energy harvesting using a mechanical oscillator. The capabilities and robustness of the computational framework are validated against a variety of benchmarking single-phase and multiphase FSI problems from the literature, which include a three-dimensional swimming eel model to demonstrate the significant speedup and efficiency that result from employing the present multilevel subcycling FSI scheme.

Online Airgap Flux Based Diagnosis of Rotor Eccentricity and Field Winding Turn Insulation Faults in Synchronous Generators

Rotor faults in a synchronous generator severely deteriorate its performance, reducing the operation efficiency and reliability. Most of the field-wide accepted methods require stoppage of generator operation and disassembly, and online diagnosis of rotor faults is difficult due to the lack of dependable online methods for sensitive rotor fault detection. Therefore, online methods that can reliably and unambiguously detect rotor field winding and eccentricity faults before they lead to machine failure are required. This paper presents a new method for detecting and distinguishing rotor field winding insulation and eccentricity faults online during synchronous generator operation based on measurements from airgap flux probes, which are installed in most synchronous generators used for electric power generation. A non-complex, time domain analysis method is proposed which makes use of the voltage induced in the airgap flux sensor for a reliable prediction of the presence and identification of rotor field winding turn insulation failure and rotor dynamic eccentricity. The method is tested and verified experimentally on a 5 hp synchronous generator and on measurements from a 330 MW pumped storage generator.