Cyber-physical Simulation Research Articles

A Real-time Cyber-Physical Simulation Testbed for Cybersecurity Assessment of Large-Scale Power Systems

A Real-time Cyber-Physical Simulation Testbed for Cybersecurity Assessment of Large-Scale Power Systems

A real-time multiphysics model of a pressurized solid oxide electrolysis cell (SOEC) for cyber-physical simulation

A real-time multiphysics model of a pressurized solid oxide electrolysis cell (SOEC) for cyber-physical simulation

ECS-Grid: Data-Oriented Real-Time Simulation Platform for Cyber-Physical Power Systems

ECS-Grid is the first data-oriented real-time electromagnetic transient simulation platform for cyber-physical power systems (CPPS). Traditional simulation tools are constrained by object-oriented programming (OOP) architecture, which is now a significant obstruction to creating a comprehensive cyber-physical simulation. Therefore, the proposed ECS-Grid platform follows a new data-oriented paradigm based on an Entity-Component-System (ECS) framework, which delivers higher flexibility, extensibility, scalability, and performance to support cyber-physical system research. ECS-Grid proposes a layer of virtual intelligent electronic devices (vIEDs) to model IEDs in CPPSs. The vIEDs directly talk to physical components and communicate asynchronously with cyber services via the proposed high-performance JSON-like binary protocol. Tests with the islanding and the man-in-the-middle cyber attack scenarios on a 711-node AC-DC microgrid cluster based on a modified CIGRE 15-Bus system are performed and give accurate results. A faster-than-real-time performance is achieved on the 10th Gen Intel <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> Core <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TM</sup> i7 computer, and real-time performance is achieved on distributed embedded NVIDIA <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> Jetson platform. The ECS-Grid design and test results demonstrate the potential of the ECS data-oriented paradigm and may inspire the renovation of industrial simulation software.

Rapid load transition for integrated solid oxide fuel cell – Gas turbine (SOFC-GT) energy systems: A demonstration of the potential for grid response

Rapid load transition is an essential requirement for integrated energy systems to maintain grid resilience as more renewable resources are added to the grid. Integrated solid oxide fuel cell – gas turbine (SOFC-GT) systems can provide high efficiency and low carbon emissions over a broad range of turndown. These hybrids also have the potential to enable rapid grid response. The challenge has been to demonstrate effective control strategies to manage load transitions. In the present study, a load transition of ∼50% was achieved in 10 s using a novel but simple strategy. Power demand on the SOFC and the GT were ramped down concurrently. During this transition, the SOFC anode fuel was manipulated to maintain SOFC fuel utilization while the cathode inlet air flow and temperature were also manipulated to thermally protect the SOFC. This study was conducted using the Hybrid Performance (Hyper) facility at the National Energy Technology Laboratory (NETL) in a co-simulation environment with the Idaho National Laboratory (INL)’s grid-simulation. The load ramping strategy was tested using a hardware-based cyber-physical simulation methodology. The results demonstrate a high-fidelity representation of SOFC-GT hybrid dynamics and validation of the control strategy. Thermal and electrochemical transients indicated that the SOFC was well protected during rapid load turndown without violating operability constraints. This demonstration revealed the non-linear nature of tightly coupled SOFC-GT system components, especially the non-linear response of SOFC cathode air flow and inlet temperature controls. These results highlight the needs and challenges in developing adaptive automatic controls for autonomous rapid load transitions. This work demonstrates that SOFC-GT hybrids are a viable option to provide the fast-ramping characteristics essential to accommodate high levels of variable renewable power while maintaining grid resilience, reliability, and environmental performance. The results also demonstrate the utility of co-simulation in advancing the tightly-coupled integrated energy systems needed to meet goals for zero-carbon power generation.

Resilient cyber physical simulation for modified back-to-back converter with sliding mode control

This paper presents an approach on to the testing of cyber–physical controller-hardware in loop testing of modified back to back converter for three phase applications with sliding mode control. The proposed back-to-back converter is capable of feeding supply for two independent loads. The uncontrolled rectifier is utilised as front end converter and a modified back end converter is designed. The back converter has reduced semiconductor switches and rating of the DC link is reduced. The power electronics model is designed by using Multisim tool which is a pspice based electrical simulation software. The control terminals are interfaced with LabVIEW using co-simulation interface. The co-simulation technique involves controller on target control unit and the plant model in a real-time computer (Multisim). The DSP processor TMS320F2812 which has the control algorithm for controlling the plant model is connected with the NI Compact Date Acquisition (C-DAQ) module and is interfaced with LabVIEW, where the data acquisition takes place. The control strategy for back end control is based on integral sliding mode control. The performance analysis of the modified back-to-back converter is analysed with cyber physical hardware in loop and co-simulation framework.

Non-simultaneous real-time hybrid simulation of a numerical and experimental mechanical system with moderate nonlinearities via iterative coupling based on Frequency Response Functions

The coupled simulation of numerical and real subsystems is sometimes called ‘hybrid substructuring’, ‘hardware in the loop (HIL)’, ‘cyberphysical simulation’, or ‘hybrid simulation’, and is an active field of research. In this publication, an iterative algorithm for a coupled simulation of a numerical subsystem and a real (experimental) one is presented. The term ‘iterative’ means that the subsystems are not computed or tested simultaneously but in loops one after the other. After each loop run, new control signals are computed so that the deviation of the coupling forces and displacements becomes smaller with each iteration. If the coupling quantities are equal, then the systems are coupled in a mechanical sense because of the cutting force principle. The proposed method works for quasi-static (slow speed) and dynamically reacting systems as well as for subsystems with moderate nonlinearities. The iterative character has several consequences: (1) No controllers are necessary. (2) The speed of the data exchange is not critical. (3) The method can only be applied to components whose properties do not change during the simulation (e.g. due to damage). Privacy between the two domains is guaranteed, as no explicit mathematical models in the sense of Finite Element (FE) structures or the like, but only frequency response functions, have to be exchanged. A possible application scenario could look as follows: An original equipment manufacturer (OEM) provides a web interface to a complex overall simulation model. A (geographically distant) supplier starts an iterative co-simulation with a somehow modified component (e.g. a bearing). Both sides can thus estimate the impact on the overall system. After explaining the theory, two examples are presented. The first concerns the coupled simulation of two pure numerical systems. In the second example, mixed numerical and experimental subsystems are coupled. Hence, a simple wheel suspension is considered, where the shock absorber is the real part on a test bench.

A Fast Protection of Multi-Terminal HVDC System Based on Transient Signal Detection

HVDC technologies are widely acknowledged as one of solutions for the interconnection of renewable energy resources with the main electric power grid. The application of the latest modular multi-level converter (MMC) makes power conversion much more efficient. Due to the relatively low impedance in a DC system, DC fault currents may rise to an extremely high level in a short period of time, which can be very dangerous for HVDC converters. To improve the sustainability and security of electricity transmission, protection solutions for HVDC systems are being developed. Nevertheless, they have various drawbacks on fault signal detection and timely clearance. This paper proposes a protection method that provides a fast and reliable solution addressing those drawbacks. A protection algorithm based on travelling wave simulation and analysis is proposed to detect abrupt transient signals. The algorithm shows high efficiency, reliability, selectivity and has low sampling frequency requirements. The proposed protection method has been validated through a cyber-physical simulation platform, developed using a real-time digital simulator (RTDS) and IEC 61850 communication links. The obtained results show that the proposed method has good potential for practical applications.

Cyber‐physical system testbed for power system monitoring and wide‐area control verification

The electric power system is intrinsically a cyber-physical system (CPS) with power flowing in the physical system and information flowing in the cyber-network. Testbeds are crucial for understanding the cyber-physical interactions and provide environments for prototyping novel applications. This study proposes a four-layer architecture for CPS testbeds with emphases on communication network emulation and networked physical components. A configurable software-defined network is employed to bridge physical components with wide-area applications for closed-loop control. In order to distribute physically coupled devices into multiple software simulations, this study proposes a data broker setup based on a distributed messaging environment to achieve low-latency data streaming. The decoupled design with data streaming allows for building testbed components as modules and running them in a distributed manner. Case studies verify the data broker setup for low-latency sensing and actuation, as well as the communication emulation setup for the desired network latency. Also illustrated is a replay attack scenario using synchrophasors in the Western Electricity Coordinating Council (WECC) 181-bus system for demonstrating the closed-loop cyber-physical simulation capability of the testbed.

Distributed Topology Identification Information Model of Distribution Network Based on IEC61850

This paper proposes a distributed topology information model based on IEC61850 to support the distributed topology processing function of the distribution network automation system. The information model expands the new logical nodes and common data classes for storing local topology information of local subgraphs and communication information of adjacent intelligent electronic devices. By using the distributed adaptation of graph connectivity algorithm and the extended IEC61850 information model, the dynamic topology identification function of the distribution network structure is realized. The extended information model and topology recognition algorithm are verified by the cyber-physical simulation system.

Effects of centralized and local PV plant control for voltage regulation in LV feeder based on cyber-physical simulations

In the modern power system, both local and centralized reactive power control strategies for photovoltaic (PV) plants, are proposed and compared. While local control improves the network security, it lacks the optimization benefits from centralized control strategies. Therefore, this paper considers the coordination of the two control strategies, depending on external impact from the weather system and consumer behavior, in a low voltage (LV) distribution feeder. Through modeling and simulation in an established real-time cyber-physical simulation platform, the LV network is evaluated with both local and centralized control. A set of boundaries for coordinating between the two strategies are identified, which can help network operators in deciding suitable control in different operating situations. Furthermore, the cyber-physical simulation platform, is used to study the impact of physical perturbations, i.e. changes in irradiance and consumption, and cyber disturbances, in form of communication channel noise, is evaluated for the control strategies. Results show how small and large disturbances in the cyber system affects the centralized control strategy optimizer performance.

Synchro-Measurement Application Development Framework: An IEEE Standard C37.118.2-2011 Supported MATLAB Library

Electrical power system monitoring, protection, operation, and control schemes are undergoing significant changes toward the next generation fully automated, resilient, and self-healing grids. At present, there still exists a lack of available user-friendly tools for the synchronized measurement technology supported application design. This paper presents a synchro-measurement application development framework (SADF) to promote a simplified design and thorough validation of synchro-measurement (IEEE Standard C37.118.2-2011) supported user-defined applications under realistic conditions. The proposed SADF supports online receiving of a phasor measurement unit (PMU) or phasor data concentrator (PDC) provided data stream and enables simultaneous use of processed machine-readable synchro-measurements in advanced user-defined applications. This paper fills the scientific gap between the IEEE Standard C37.118.2-2011 specifications and its implementation by proposing a novel robust communication technique and efficient synchro-measurement data parsing methodology. As a proof of concept, the proposed SADF is implemented as a novel open-source MATLAB library. Combining this library with MATLAB’s signal processing and visualization functions allows mastering the design and validation of complex wide-area monitoring, protection, and control applications, as well as PMU/PDC performance and compliance verification. Finally, this paper verifies the proposed library against the standard specifications, assesses its interoperability and performance via a cyber-physical simulation platform, and presents online voltage magnitude monitoring as an example application.

Synchronized measurement technology supported AC and HVDC online disturbance detection

In electric power system, disturbance detection has become an important part of grid operation and refers to the detection of a voltage and current excursion caused by the wide variety of electromagnetic phenomena. This paper proposes a computationally efficient and robust algorithm for synchronized measurement technology (SMT) supported online disturbance detection, suitable for AC and HVDC grids. The proposed algorithm is based on the robust median absolute deviation sample dispersion measure to locate dataset outliers. The algorithm is capable of identifying the disturbance occurrence and clearance measurement sample based on the dynamic criteria, driven by present power system conditions. The effectiveness of the proposed algorithm is verified by real-time simulations using a cyber-physical simulation platform, as a co-simulation between the SMT supported electric power system model and underlying ICT infrastructure. The presented results demonstrate effectiveness of the proposed algorithm, making it suitable for an AC and HVDC online disturbance detection application or as a pre-step of backup protection schemes.

Cyber-Physical Simulation and Optimal Mitigation for Shipping Port Operations

Modern shipping ports require computer systems to accommodate an increasing number of port calls, larger vessel sizes, and tighter supply chains. Disruptions to assets on these networks have the potential to propagate to other critical infrastructures at great economic cost. Such disruptions may be introduced intentionally by adversaries that include nation states, organized crime, hacktivists, and insiders. Area Maritime Security Committees (AMSCs) must develop security plans to minimize disruptions’ impact. This paper explores one way to couple a simulation of the flow of commodities through a shipping port with an optimization that minimizes the cost of disruptions to the port transportation system. Our intent is to enable stakeholders to run what-if scenarios, to understand the impact and effect of cyber-physical disruptions, and to optimally mitigate their effect. This research, based on ongoing fieldwork with Port Everglades and the USCG, hopes to improve security policies that integrate cyber and physical effects.

Technology-Enhanced Learning in Cyber-Physical Systems Embedding Modeling and Simulation

Globalization in international research and development is changing the way universities need to educate and train students. As universities prepare their graduates for the needs of the 21st century and the global market economy, they face significant pressure to overhaul their well-established traditional curriculums and adapt the conventional delivery of course materials to new methodologies appropriate for the cooperative environment. Engineering Science is an emerging area with the potential to provide graduates with the skills needed to meet the challenges of complex designs of cyber-physical systems and shorten their time to market window. To ensure that university graduates are prepared to meet the challenges of a global market, the instructional methodology needs to be broadened. Such technology-enhanced learning is required to provide engineering students with the skills, tools, and training needed to verify and validate the details of complex cyber-physical systems designs and to understand the risk involved in development of inaccurate models. The results obtained from the accurate models can be analyzed to ensure the design of a cyber-physical system will be error-free and the system developed will perform according to the design specification and requirements.

Cyber-Physical Simulation for Virtual Characterization of SOFC Thermomechanical Response Within Hybrid Fuel-Cell/Gas Turbines

Abstract Solid-oxide fuel-cell (SOFC)/gas-turbine hybrid systems possess the capacity for unprecedented performances, such as electric efficiencies nearly twice that of conventional heat engines at variable scale power ratings inclusive of distributed generation; however, reliably integrating such technologies is critical. Dynamic operability challenges ranging from surge-stall events in the turbomachinery to threatening thermally induced stresses within the fuel cells are formidable. An effective means of characterizing the operability of such systems requires a simulation approach of high fidelity yet reduced sacrificial risk associated with empirical investigation of SOFC stacks. Accordingly, a unique cyber-physical simulation (CPS) was developed inclusive of a spatio-temporal SOFC computational model interfaced with a retrofitted turbine. The model had an extensively broad operating range, as compared to other models that have been developed, with the capability to characterize inert heating, electrochemical start-up, and on and off design operation. A comprehensive parametric characterization was done for initial electrochemical light-off with variability in compressor by-pass valve position and initial fuel-cell load for both closed loop and open loop (OL) turbine speed system configurations. The impact of cold-air (CA) by-pass, as well as initial fuel-cell load on system parameters that directly affect SOFC operation, such as inlet air temperature, pressure, and flow, along with turbine speed and thermal effluent dynamics are presented and discussed. Additionally, the full spatio-temporal capability was exhibited and utilized in examining the impact of electrochemical start-up upon SOFC temperature and temperature gradients as a result of local current density and by-product heat distribution. Ultimately, a comprehensive parametric study, characterizing SOFC and hybrid system response to electrochemical start-up along the decision variable values of initial fuel-cell load, as well as CA by-pass valve position, was completed; this illustrated an advanced simulation platform for gathering such insights about developmental fuel-cell systems.

DMS Cyber-Physical Simulation for Assessing the Impact of State Estimation and Communication Media in Smart Grid Operation

Energy management systems for the operation of distributed energy resources, distribution storage devices, and responsive loads will be embedded in distribution management systems (DMSs) as advanced functions that rely on accurate input data and fast communication signals. For a proper DMS design, the impact of the state estimation uncertainties and of the communication system delays should be evaluated. The paper presents an integrated software package for the cyber-physical simulation of DMS taking into account the accuracy of state estimation and measurements. The effectiveness of a wireless Wi-Max communication system has been tested on the rural Italian representative network produced by the research project ATLANTIDE. Results proved the need of cosimulation packages in modern distribution systems.

An integrated cyber-physical simulation environment for smart grid applications

The concept of Cyber-Physical Systems (CPSs), which combine computation, networking, and physical processes, is considered to be beneficial to smart grid applications. This study presents an integrated simulation environment to provide a unified platform for the investigation of smart grid applications involving power grid monitoring, communication, and control. In contrast to the existing approaches, this environment allows the network simulator to operate independently, importing its results to the power system simulation. This resolves conflicts between discrete event simulation and continuous simulation. In addition, several data compensation methods are proposed and investigated under different network delay conditions. A case study of wide-area monitoring and control is provided, and the efficiency of the proposed simulation framework has been evaluated based on the experimental results.

SimConnect and SimTalk for distributed cyber-physical system simulation

Real-time embedded and cyber-physical systems challenge simulation disciplines due to the heterogeneous tools used to model components in the system exploration and design phases. Termed “heterogeneity,” the mixed-model problem challenges multi-simulator coordination, where event causality must be preserved among simulators with different models of computation, signals, criteria for time advancement, and levels of abstraction. SimConnect and SimTalk enable heterogeneous, distributed, hardware/software co-simulation with a simplified backplane approach, emphasizing the simulation of software interacting with simulated world-model electrical, mechanical, and physical effects. The structure of SimConnect and SimTalk is described, adhering to the properties of a Kahn Process Network. Application of the tools to the coordination of three different simulators (TExaS, Ngspice, and Simulink) is presented to simulate closed-loop, hardware/software-based, Proportional-Integral-Derivative/Pulse-Width-Modulated control of a direct current motor. Results demonstrate agreement among simulator coordinations with configurable tradeoffs in speed versus accuracy.