Cyber-physical Modeling Research Articles

Cyber-Physical Modeling and Vulnerability Assessment of Substations for Transmission System Operator

In bulk power systems, the majority of interaction between cyber and physical components takes place in substations. However, in most of the cyber–physical power system models the physical layer is typically done using the bus-branch (BB) model, where each substation is considered as a single node. This approach will not capture the details of the cyber layer. This paper proposes a framework to model the substations using node-breaker (NB) models for physical system representation so that the detailed station configurations, the current and the voltage transformer positions, arrangements of protective relays, bay control units and associated communication infrastructure within the substations and its dependencies on the physical elements can be captured effectively using a single cyber–physical graph. Keeping a transmission system operator in view, who does not use power flow and security assessment tools for station operations and maintenance, a vulnerability assessment approach is proposed to assess the risk using some representative attack scenarios. The proposed approach is demonstrated using WECC 3-machine system for breaker and half station configuration. The attack scenarios are developed based on the real substation configuration and the adversary’s ability to understand the substation protection and BI/BO operations.

Integrating Cyber-Physical Modeling for Pandemic Surveillance: A Graph-Based Approach for Disease Hotspot Prediction and Public Awareness

Integrating Cyber-Physical Modeling for Pandemic Surveillance: A Graph-Based Approach for Disease Hotspot Prediction and Public Awareness

Dynamic Modeling of Nonlinear Systems in Cyber-Physical Environments

Complex behavior understanding and prediction relies on dynamic modeling of nonlinear systems in cyber-physical contexts. Critical for improving control systems, anticipating maintenance needs, and bolstering resilience, it permits accurate portrayal of complex interactions between cyber and physical components. Guaranteeing efficient and adaptable performance in networked ecosystems is made possible by this insight. Dynamic modeling of nonlinear systems (DM-NS) in cyber-physical settings has a number of challenges, such as the need to accurately depict complex interdependencies, accommodate changes in real-time, and reduce uncertainty. Advanced modeling techniques are required to capture the subtle behaviours and maintain the accuracy of the models while trying to balance the complicated interactions between physical and cyber components. A novel strategy is suggested to tackle these obstacles: Analysing Nonlinear Systems Cyber-Physical Modeling (ANSC-PM). By integrating complex mathematical models with adaptive learning algorithms, ANSC-PM is able to characterize nonlinear system behaviours, taking into account the dynamic interplay between cyber and physical components. To remain relevant as system dynamics change, the suggested method adjusts in real-time. Numerous disciplines find ANSC-PM useful, such as control system optimization, robotic predictive maintenance, and networked environment resilience enhancement. The effectiveness of ANSC-PM is determined by careful simulation analysis, which provides insight into its possible benefits in improving system performance, flexibility, and resilience in complex cyber-physical settings. Developing a thorough and flexible strategy that is adapted to the intricacies of cyber-physical systems, this research makes a substantial contribution to the progress of dynamic modeling approaches.

Cyber-physical Modeling Technique based Dynamic Aggregation of Wind Farm Considering LVRT Characteristic

With the increasing penetration of wind power, large-scale integrated wind turbine brings stability and security risks to the power grid. For the aggregated modeling of large wind farms, it is crucial to consider low voltage ride-through (LVRT) characteristics. However, in aggregation methods, the approximate neglect behavior is essential, which leads to inevitable errors in the aggregation process. Moreover, the lack of parameters in practice brings new challenges to the modeling of a wind farm. To address these issues, a novel cyber-physical modeling method is proposed. This method not only overcomes the aggregation problem under the black-box wind farm but also accurately realizes the aggregation error fitting according to the operation data. The simulation results reveal that the proposed method can accurately simulate the dynamic behaviors of the wind farm in various scenarios, whether in LVRT mode or normal mode.

ВИКОРИСТАННЯ КІБЕРФІЗИЧНИХ СИСТЕМ ДЛЯ ДОСЛІДЖЕННЯ АГРЕГАТІВ АВТОМОБІЛЯ

Research of control systems of vehicle transmission units is an important stage in the process of creating the latest developments in this area. One of the problems on the way to create and adapt to specific operating conditions of control systems of transmission units is an experimental studies of their operation, including as part of the vehicle. The main difficulty in conducting experimental research is often the high cost of the necessary equipment and the problems associated with the reproduction on a particular experimental stand of various operating conditions of the system. One of the solutions to this problem is the use of cyberphysical systems to test vehicle units and study their control systems. The purpose of the work is theoretical substantiation and practical creation of cyberphysical system, which allows to work out algorithms of control of transmission element in different operating conditions without need of its installation on real vehicle and consists of electropneumatic clutch control mechanism realized at physical level and model of vehicle transmission elements. The approaches adopted in the work to achieve this goal are based on the laws of physics, the main processes and phenomena reproduce and study by mathematical modeling. The research technique which allows to combine experimental methods with receptions of mathematical modeling is offered. The concept of cyberphysical modeling of complex devices and their control systems is presented. The process of transition from the physical to the model level of the cyberphysical system is described, the software and hardware means for its realization are offered. The study of the created cyberphysical system and the comparison of the obtained results with the experimental data of the study of the electropneumatic clutch control drive allowed to draw a conclusion about the possibility of using the proposed approach to test vehicle units. The proposed approaches and the given material and technical base can be used in the design of new and research of previously created units and systems of vehicles. Keywords: cyberphysical model, pneumatic cylinder, DC motor, Arduino, solenoid valve, angle of rotation.

Design and implementation of an autonomous service robot based on cyber physical modeling systems

An autonomous robot is designed and implemented to support the service works. Many technologies were adapted, namely human-robot interaction order system, path planning and mapping in indoor, Robot Operating System (ROS), and Cyber Physical System (CPS). Many subsystems are developed and constructed based on ROS to implement a human-interaction action in completing service robot tasks. A human-robot interaction order system is designed for the convenient human servicing purpose. Therefore, the customer quickly finds the commodity information through the internet. This system recommends the commodity according to the content of the database. In addition, the customer makes an order by touch screen interface, and then it sends a command to control the robot to deliver the commodity. In the second subsystem, it includes path planning and mapping generation. The well-known simultaneous localization and mapping (SLAM) concept with a Rao-Blackwellized particle filter (RBPF) addresses the appropriated maps after completing the exploration of the indoor environment. In order to reach better robustness and agility, the hybrid path planning algorithm includes a global A* algorithm and local dynamic window approach (DWA) to navigation. In the third subsystem, the Gazebo makes the perfect construction of CPS design. Finally, the simulation and implementation of dual-arm robot navigation with the interactive order situation to efficiently support servicing actions of the robot and finish the required tasks.

CYBER-PHYSICAL MODELING OF THE LEADING AND LED ELECTRIC CAR'S JOINT MOVEMENT

With the help of cyber-physical modeling, the main features of the movement of the master-slave communication of self-driving electric vehicles are determined. Leading electric car leader made in the form of a light tricycle. A driven electric car realized on a heavy caterpillar platform. There is no mechanical connection between the master and the driven electric car. Both electric cars have a microcontroller that controls the speed of rotation of the wheels. It uses the driving control principle similar to driving a tractor. The main information is the value of the master and slave electric vehicle speeds, which measures every 0.1 s. Both microcontrollers equip with a Bluetooth module. The most crucial part of implementing the cyber-physical model of the leader-driven electric car is the need to introduce a human-driver team into the model. It proposes to give the driver the ability to remotely control the movement of the leader-driver of the car via Bluetooth radio on a smartphone. The connection between the leader and led of electric vehicles in the joint's movements and the human control team is based on the Mesh Network (Flood) principle. Ключові слова : cyber-physical system, control, master-driven electric cars, self-driving electric cars, safe distance between vehicles.

Hierarchical multiple time scales cyber-physical modeling of demand-side resources in future electricity market

The electricity market reform in China stimulates the capacity of demand-side resources regulation and provides a new approach to promote large-scale renewable energy access to power grid. However, there is no effective modeling method to describe the participation of demand-side resources in power grid regulation, which seriously affects the research on the response strategy of demand-side resources under the electricity market environment. Aiming at the problem above, this paper presents a multiple hierarchical and multiple time scales modeling method of demand-side resources based on cyber-physical system theory. First, a multiple hierarchical and multiple time scales modeling framework of demand-side resources based on cyber-physical system theory is proposed. Second, on the basis of the modeling framework, the multi-dimensional variable coupling relationships of the energy flow, the information flow and the capital flow of demand-side resources are analyzed. Finally, an example of feasible modeling method under this framework is presented, and the correctness of the presented modeling method is verified. This paper gives full consideration to the coupling relationship of multiple hierarchies, multiple time scales and multi-dimensional variables of demand-side resources under the power market environment, and proposes a demand-side response resources model based on cyber-physical system theory, which lays a solid foundation for future research on demand-side resources' participation in power grid regulation.

Hybrid Gearbox Modeling Using Modelica4.0

Gearbox modeling with mixed continuous and discrete events has been studied for long time. The gearbox power loss depends on the angular velocity and load. In this report, the LossyGear model of the Modelica standard library was constructed with a new configuration from the viewpoint of system engineering utilizing the synchronous feature of Modelica Standard Library 4.0. The proposed method can also be regarded as a case study for general cyber-physical modeling approach.

Research on operation control of low-voltage MTDC system in a cyber-physical environment

Cyber-physical system is becoming a new feature and hot topic in the development of smart grid and DC power distribution system. Based on the standardized cyber-physical modeling and communication system — IEC 61850, this paper establishes the operation control architecture of the low-voltage multi-terminal DC (LV-MTDC) system. The coordinated operation control strategies including power electronic transformer (PET), voltage source converter (VSC) is proposed. Then a cyber-physical model of the system based on IEC 61850 is built, according to the application requirements of operation control in the LV-MTDC system. On this basis, the implementation method of system operation control based on IEC 61850 is proposed, including the software/hardware design of intelligent electronic device (IED), dispatching operation and uninterrupted power supply. The simulation environment is further built to verify the system operation control technology, and the test platform is used to carry out the actual tests. The research results show that the operation control technology for the LV-MTDC system proposed in this paper is feasible, which can guarantee the rapid and accurate information exchange of control commands and settings, and thus effectively realize the operation control of the LV-MTDC system under complex conditions.

Comfort-aware Cooperative Cruise Control of Multiple High-speed Trains: An Artificial Potential Field Approach

In this work, the cruise control problem of multiple high-speed trains movements is investigated. Different from the classical PID control method applied in the practical highspeed train operation system, in this paper, a cooperative cruise control strategy considering both safety and passenger comfort based on layered potential function is proposed. First, the cyber-physical modeling of the high-speed trains system is presented, where the physical layer models the dynamic characteristic, and the cyber layer describes the communication topology. Second, a cooperative control algorithm based on layered potential function is designed. The underlying artificial potential function is introduced to keep a safe distance between adjacent high-speed trains, and the speed consensus rule is realized through the consensus algorithm. The hyperbolic tangent function is selected as the upper artificial potential function to ensure the acceleration of the high-speed train within a comfortable range. Finally, the stability of the control system is proved by the Lyapunov stability theorem, and simulations verify the effectiveness of the control strategy.

Cyber-physical modeling and simulation: A reference architecture for designing demonstrators for industrial cyber-physical systems

The application of models and simulations is well-established in systems engineering and development. To adapt this approach to the digital age, we propose the concept of “cyber-physical modeling and simulation (CPMS)” which enables to constitute cyber-physical systems (CPS) with scalable complexity, modularity and variability in size. Based thereon, we derive a reference architecture for designing demonstrators for industrial CPS. The reference architecture offers a structured design space and attributed components which constitute the demonstrators with regard to their application objectives and scenarios. As a viability assessment, we apply the proposed reference architecture by developing the instantiation “Portable Industrial Demonstrator for Cyber-Physical Systems (PID4CPS)”.

Synchronized Cell-Balancing Charging of Supercapacitors: A Consensus-Based Approach

The switched resistor circuit has been a popular cell balancing scheme in low-power supercapacitor applications. However, the cell balancing performance of the circuit is vulnerable to current variations and resistance deviations with the existing asynchronous cell-balancing (ACB) method. To address this challenge, in this paper, we propose a synchronized cell-balancing (SCB) method based on the consensus theory, with the aim of synchronizing cell voltages during the charging process. First, the cyber-physical modeling of the cell balancing system is presented, where the physical layer models the circuit components and the cyber layer represents the communication topology among cells. Second, a distributed voltage tracker is proposed using a consensus tracking protocol, which benefits from a good scalability. A compensator is designed to stabilize the closed-loop multiple-in-multiple-out (MIMO) system and frequency-domain methods are applied to determine the compensator parameters. A laboratory testbed has been built to verify the effectiveness of the proposed method. Experiment results show that the SCB method has a better tolerance of current variations and resistance deviations than the ACB method.

Multi-Objective Optimal Design of a Building Envelope and Structural System Using Cyber-Physical Modeling in a Wind Tunnel

This paper explores the use of a cyber-physical systems (CPS) “loop-in-the-model” approach to optimally design the envelope and structural system of low-rise buildings subject to wind loads. Both the components and cladding (C&C) and the main wind force resisting system (MWFRS) are considered through multi-objective optimization. The CPS approach combines the physical accuracy of wind tunnel testing and efficiency of numerical optimization algorithms to obtain an optimal design. The approach is autonomous: experiments are executed in a boundary layer wind tunnel (BLWT), sensor feedback is monitored and analyzed by a computer, and optimization algorithms dictate physical changes to the structural model in the BLWT through actuators. To explore a CPS approach to multi-objective optimization, a low-rise structure with a parapet wall of variable height is considered. In the BLWT, servo-motors are used to adjust the parapet to a particular height. Parapet walls alter the location of the roof corner vortices, reducing suction loads on the windward facing roof corners and edges, a C&C design load. At the same time, parapet walls increase the surface area of the building, leading to an increase in demand on the MWFRS. A combination of non-stochastic and stochastic optimization algorithms were implemented to minimize the magnitude of suction and positive pressures on the roof of a low-rise building model, followed by stochastic multi-objective optimization to simultaneously minimize the magnitude of suction pressures and minimize base shear. Experiments were conducted at the University of Florida Experimental Facility (UFEF) of the National Science Foundation’s (NSF) Natural Hazard Engineering Research Infrastructure (NHERI) program.

Cyber-physical Modeling of Rotation Vibration Compensation of MOCVD Substrate Bearing Disk

MOCVD large size substrate bearing disk, working in high temperature, high speed rotating and complex gas phase environment, in the high-speed rotation of the material is easy to deformation, vibration or flutter, to its rotation compensation control vibration will become very complicated. This article is based on fuzzy neural network study of bearing plate of high speed vibration, through optimal controller is designed to make the whole system performance index.

Cyber-physical Modeling of High Speed Machining of Flexible Materials

Due to the structure characteristics of flexible materials, it will easily be deformed in the cutting process and thus the cutting interface be destroyed, resulting in low-quality cutting parts. Based on the cutting process of flexible leather substance, this paper attempts to develop a new high speed vibration cutting mechanism for flexible materials. Research will be on the vibration cutting method for flexible materials, and then a high speed vibration cutting head module will be designed according to motion transformation principle of eccentric shaft and connecting rod structure. Corresponding tests and Experiments are carried out and as the result, the vibration cutting frequency is up to 20,000 times/min, with the angle error within ±1.5°. The cutting speed can achieve 120 cm/s, and work noise < 80db.

Cyber–Physical Modeling of Distributed Resources for Distribution System Operations

Cosimulation platforms are necessary to study the interactions of complex systems integrated in future smart grids. The Virtual Grid Integration Laboratory (VirGIL) is a modular cosimulation platform designed to study interactions between demand-response (DR) strategies, building comfort, communication networks, and power system operation. This paper presents the coupling of power systems, buildings, communications, and control under a master algorithm. There are two objectives: first, to use a modular architecture for VirGIL, based on the functional mockup interface (FMI), where several different modules can be added, exchanged, and tested; and second, to use a commercial power system simulation platform, familiar to power system operators, such as DIgSILENT PowerFactory. This will help reduce the barriers to the industry for adopting such platforms, investigate and subsequently deploy DR strategies in their daily operation. VirGIL further introduces the integration of the quantized state system (QSS) methods for simulation in this cosimulation platform. Results on how these systems interact using a real network and consumption data are also presented.

A Method for Cyber-Physical System Behavior Modeling and Safety Verification Based on Extended Hybrid System Description Language

The safety of Cyber-physical system(CPS) is up to its behavior, and it is a key property for CPS to be applied in critical application fields. A method for CPS behavior modeling and safety verification is put forward in this paper. The behavior model of CPS is described by extended hybrid system description language(EHYSDEL). The formal definition of hybrid program(HP) is given, and the behavior model is transformed to HP based on the definition. The safety of CPS is verified by inputting the HP to KeYmarea. The advantage of the approach is that it models CPS intuitively and verify it’s safety strictly avoiding the state space explosion

Fast and scalable 3D cyber-physical modeling for high-precision mobile augmented reality systems

Mobile augmented reality is an emerging technique which allows users to use a mobile device's camera to capture real-world imagery and view real-world physical objects and their associated cyber-information overlaid on top of imagery of them. One key challenge for mobile augmented reality is the fast and precisely localization of a user in order to determine what is visible in their camera view. Recent advances in Structure-from-Motion (SfM) enable the creation of 3D point clouds of physical objects from an unordered set of photographs taken by commodity digital cameras. The generated 3D point cloud can be used to identify the location and orientation of the camera relative to the point cloud. While this SfM-based approach provides complete pixel-accurate camera pose estimation in 3D without relying on external GPS or geomagnetic sensors, the preparation of initial 3D point cloud typically takes from hours to a day, making it difficult to use in mobile augmented reality applications. Furthermore, creating 3D cyber-information and associating it with the 3D point cloud is also a challenge of using SfM-based approach for mobile augmented reality. To overcome these challenges in 3D point cloud creation and cyber-physical content authoring, the paper presents a new SfM framework that is optimized for mobile augmented reality and rapidly generates a complete 3D point cloud of a target scene up to 28 times faster than prior approaches. Key improvements in the proposed SfM framework stem from the use of (1) state-of-the-art binary feature descriptors, (2) new filtering approach for accurate 3D modeling, (3) optimized point cloud structure for augmented reality, and (4) hardware/software parallelism. The paper also provides a new image-based 3D content authoring method designed specifically for the limited user interfaces of mobile devices. The proposed content authoring method generates 3D cyber-information from a single 2D image and automatically associates it with the 3D point cloud.

Cyber-Physical Modeling and Cyber-Contingency Assessment of Hierarchical Control Systems

Online closed-loop hierarchical control systems (HCSs) are widely used in power-system operation. Like typical cyber-physical systems, the contingencies on the cyber side of an HCS may lead to inappropriate control commands, which will influence the physical power system. To evaluate the degree to which these inappropriate control commands influence the power system, we propose a cyber-physical equivalent model for HCSs. In this model, the HCS cyber network is abstracted to a directed graph consisting of data nodes and directed branches, and connectivity is described by using a node-branch incidence matrix. Using this strategy, we can describe the general information flow in an HCS using mathematical equations on the basis of which quantitative evaluation can be carried out. Furthermore, by using existing operation records, several kinds of typical cyber-contingencies are also modeled on the basis of which cyber-contingency assessment (cyber-CA) can be implemented by using a model-based approach. Considering the computational efficiency, such an approach keeps only key characteristics of the information flow rather than all features of the cyber network. In the case study, a coordinated secondary-voltage control system is studied as an example. The physical impacts of various cyber-contingencies on different data transmission and processing modules are compared. The results show that the model-based method provides improved efficiency compared with conventional simulation-based methods while maintaining accuracy.