Authors: P. Ghosh, S. Eisele, A. Dubey, M. Metelko, I. Madari, P. Volgyesi, G. Karsai
Abstract: The vision of the ‘Smart Grid’ anticipates a distributed real-time embedded system that implements various monitoring and control functions. As the reliability of the power grid is critical to modern society, the software supporting the grid must support fault tolerance and resilience of the resulting cyber-physical system. This paper describes the fault-tolerance features of a software framework called Resilient Information Architecture Platform for Smart Grid (RIAPS). The framework supports various mechanisms for fault detection and mitigation and works in concert with the applications that implement the grid-specific functions. The paper discusses the design philosophy for and the implementation of the fault tolerance features and presents an application example to show how it can be used to build highly resilient systems.
Journal: Journal of Systems Architecture, Volume 109, October 2020, 101759
Authors: H. Tu, Y. Du, Y. Hui, A. Dubey, S. M. Lukic, and G. Karsai
Abstract: Microgrids are seen as an effective way to achieve reliable, resilient, and efficient operation of the power distribution system. Core functions of the microgrid control system are defined by the IEEE standard 2030.7; however, the algorithms that realize these functions are not standardized, and are a topic of research. Furthermore, the corresponding controller hardware, operating system, and communication system to implement these functions vary significantly from one implementation to the next. In this paper, we introduce an open-source platform, Resilient Information Architecture Platform for the Smart Grid (RIAPS), ideally suited for implementing and deploying distributed microgrid control algorithms. RIAPS provides a design-time tool suite for development and deployment of distributed microgrid control algorithms. With support from a number of run-time platform services, developed algorithms can be easily implemented and deployed into real microgrids. To demonstrate the unique features of RIAPS, we propose and implement a distributed microgrid secondary control algorithm capable of synchronized and proportional compensation of voltage unbalance using distributed generators. Test results show the effectiveness of the proposed control and the salient features of the RIAPS platform.
Conference: IEEE Transactions on Industrial Electronics, 15 November 2019
Authors: P. Ghosh, S. Eisele, A. Dubey, M. Metelko, I. Madari, P. Volgyesi and G. Karsai
Abstract: The vision of the ’Smart Grid’ assumes a distributed real-time embedded system that implements various monitoring and control functions. As the reliability of the power grid is critical to modern society, the software supporting the grid must support fault tolerance and resilience in the resulting cyber-physical system. This paper describes the fault-tolerance features of a software framework called Resilient Information Architecture Platform for Smart Grid (RIAPS). The framework supports various mechanisms for fault detection and mitigation and works in concert with the applications that implement the grid-specific functions. The paper discusses the design philosophy for and the implementation of the fault tolerance features, and presents an application example to show how it can be used to build highly resilient systems.
Conference: 22nd IEEE International Symposium on Real-Time Distributed Computing (ISORC), Valencia, Spain, May, 2019
Authors: T. Krentz and G. Karsai
Abstract: Smart infrastructure demands resilient data storage, and emerging applications ask questions about this data over time. Typically, time-series databases serve these queries; however, cloud-based time-series storage can be prohibitively expensive. As smart devices proliferate, the lump sum of computing power and memory available in our connected infrastructure provides the opportunity to move resilient time-series data storage and analytics to the edge. This paper proposes time-series storage in a Distributed Hash Table (DHT), and a novel keygeneration technique that provides time-indexed reads and writes for key-value pairs. Experimental results show this technique meets demands for smart infrastructure situations.
Conference: 22nd IEEE International Symposium on Real-Time Distributed Computing (ISORC), Valencia, Spain, May, 2019
Authors: H. Tu, Y. Du, H. Yu, A. Dubey, S. Lukic and G. Karsai
Abstract: Microgrids are seen as an effective way to achieve reliable, resilient, efficient and economical operation of the power distribution system, in face of severe weather events causing more frequent power disruptions on the bulk power grid. Core functions of the microgrid control system are defined by the IEEE 2030.7 standard; however the algorithms that realize these core functions are not standardized, and are a topic of research. Furthermore, the corresponding controller hardware, operating system, and communication system that serves for the algorithms are not specified. Implementing a microgrid controller from scratch is difficult due to the lack of reusable software libraries and platforms. In this paper, we present an open-source platform, Resilient Information Architecture Platform for the Smart Grid (RIAPS), for microgrid control. Beyond providing a run-time system, RIAPS has a design-time toolsuite that can significantly shorten the development and deployment of microgrid control algorithms. With support from a number of platform services such as a communication framework, real-time scheduling capability, high-precision time synchronization, etc., the developed algorithms can be tested in a close-to-reality environment and easily ported into real microgrids. We present two algorithms implemented on the RIAPS platform to demonstrate its salient features.
Conference: 9th Microgrid Global Innovation Forum, Washington, D.C. March, 2019
Authors: A. Dubey, G. Karsai, P. Volgyesi, M. Metelko, I. Madari, H. Tu, Y. Du, and S. Lukic
Journal: IEEE Embedded Systems Letters
Abstract: This letter presents an overview of design mechanisms to abstract the device access protocols in resilient information architecture platform for smart grid, a middleware for developing distributed smart grid applications. These mechanisms are required to decouple the application functionality from the specifics of the device mechanisms built by the device vendors.
Download Paper | DOI: 10.1109/LES.2018.2845854
Keynote Forum Presentation
Authors: G. Karsai, in collaboration with A. Dubey, S. Lukic, A. Srivastava
Conference: 1st International Conference on Smart Grid Technologies, Singapore, 09/2017
Authors: S. Eisele, G. Pettet, A. Dubey, G. Karsai
Abstract: As the number of low cost computing devices at the edge of network increases, there are greater opportunities to enable novel, innovative capabilities, especially in decentralized cyber-physical systems. For example, in an urban setting, a set of networked, collaborating processors at the edge can be used to dynamically detect traffic densities via image processing and then use those densities to control the traffic flow by coordinating traffic light sequences, in a decentralized architecture. In this paper we describe a testbed and an application framework for such applications.
Conference: Fog World Congress, Santa Clara, CA, October 30 - November 1, 2017
Authors: P. Volgyesi, A. Dubey, T. Krentz, I. Madari, M. Metelko, and G. Karsai
Abstract: This paper presents the time synchronization infrastructure for a low-cost run-time platform and application framework specifically targeting Smart Grid applications. Such distributed applications require the execution of reliable and accurate time-coordinated actions and observations both within islands of deployments and across geographically distant nodes. The time synchronization infrastructure is built on well-established technologies: GPS, NTP, PTP, PPS and Linux with real-time extensions, running on low-cost BeagleBone Black hardware nodes. We describe the architecture, implementation, instrumentation approach, performance results and present an example from the application domain. Also, we discuss an important finding on the effect of the Linux RT_PREEMPT real-time patch on the accuracy of the PPS subsystem and its use for GPS-based time reference
Conference: Rapid Systems Prototyping (RSP), Seoul, S. Korea, IEEE, October 19-20, 2017
Author: G. Karsai
The US power grid is a machine on a truly gigantic scale. It supplies reliable and stable electric power to more than $300 million customers via its 450,000 miles of high-voltage transmission lines. And it is also inherently distributed and decentralized: there is no single central controlling authority, rather a set of connected, interacting organizations that make energy management decisions in their own scope but coordinate with each other.
Authors: S. Eisele, I. Madari, A. Dubey, and G. Karsai
Abstract: The emerging Fog Computing paradigm is providing an additional computational layer that enables new capabilities in real-time data-driven applications. The application of Fog Computing is especially interesting in the domain of Smart Grid where it can be used to prove a decentralized application framework that reflects the ongoing trend of distribution of intelligence in Smart Systems. For example, the changes throughout the power infrastructure are blurring the boundaries between traditional generation, distribution, and consumer roles. In this paper, we briefly describe a component-based decentralized computation platform called RIAPS which provides an application architecture for such systems. We briefly describe some initial applications using this platform. Then, we focus on the design and integration choices for a resilient Discovery Manager service, which is one of the most critical component of this infrastructure. The service allows applications to discover each other and work collaboratively and to ensure the stability of the smart system.
Conference: 20th IEEE INTERNATIONAL SYMPOSIUM ON REAL-TIME COMPUTING, Toronto, Canada, IEEE, May 16-18, 2017
Authors: A. Dubey, G. Karsai, and S. Pradhan
Abstract: As the number of low cost computing devices at the edge of communication network increase, there are greater opportunities to enable innovative capabilities, especially in cyber-physical systems. For example, micro-grid power systems can make use of computing capabilities at the edge of a Smart Grid to provide more robust and decentralized control. However, the downside to distributing intelligence to the edge away from the controlled environment of the data centers is the increased risk of failures. The paper introduces a framework for handling these challenges. The contribution of this framework is to support strategies to (a) tolerate the transient faults as they appear due to network fluctuations or node failures, and to (b) systematically reconfigure the application if the faults persist.
Conference: The 2nd International Conference on Fog and Mobile Edge Computing, Valencia, Spain, IEEE, May 8-11, 2017
Authors: S. Eisele, A. Dubey, G. Karsai, and S. Lukic
Abstract: We present the current capabilities of the RIAPS platform, a decentralized fog computing architecture for geographically dispersed smart systems. These include decentralized resource discovery, component-based application design, managed interaction patterns, decentralized deployment, time synchronization, and support for device interface actors. The test bed for the demonstration consists of four single board computers, a router and a machine for running simulations. Grafana is used for visualization of sensor data.
Conference: 8th International Conference on Cyber-Physical Systems (ICCPS), pp. 91-92, ACM, Pittsburg, PA, April 18-21, 2017
Authors: W. Emfinger, A. Dubey, S. Eisele, P. Volgyesi, J. Sallai, and G. Karsai
Abstract: The emerging CPS/IoT ecosystem platforms such as Beaglebone Black, Raspberry Pi, Intel Edison and other edge devices such as SCALE, Paradrop are providing new capabilities for data collection, analysis and processing at the edge (also referred to as Fog Computing). This allows the dynamic composition of computing and communication networks that can be used to monitor and control the physical phenomena closer to the physical system. However, there are still a number of challenges that exist and must be resolved before we see wider applicability of these platforms for applications in safety-critical application domains such as Smart Grid and Traffic Control.
Conference: The First IEEE/ACM Symposium on Edge Computing, Washington, DC, October 27-28, 2016
Authors: B. Xu, H. Tu, Y. Du, H. Yu, H. Liang and S. Lukic
Abstract: Cascaded H-bridge topology has been used in grid-tied converter for battery energy storage system due to its modular structure. To fully utilize the converter's modularity, this paper propose a hierarchical distributed control architecture that consists of primary control, secondary control and battery state of charge (SOC) balancing control. Primary control ensures accurate current tracking while a distributed secondary control based on consensus algorithm is presented to regulate power sharing among modules and is proved to be stable theoretically. A distributed SOC balancing control is further introduced to improve energy efficiency of battery energy storage system. Finally, the hierarchical distributed control strategy is implemented using hardware controllers and a software platform. Besides, a carrier phase shift control is also implemented to achieve multilevel output voltage and harmonic reduction. The experimental results demonstrate the performance of the proposed control scheme effectively.
Journal: IEEE Transactions on Industry Applications, 19 November 2020
Authors: H. Tu, S. Lukic, A. Dubey and G. Karsai
Abstract: Accurate prediction of electric load is critical to optimally controlling and operating buildings. It provides the opportunity to reduce building energy consumption and to implement advanced functionalities such as demand response in the context of the Smart Grid. However, buildings are nonstationary and it is important to consider the underlying concept changes that will affect the load pattern. In this paper we present an online learning method for predicting building electric load during concept changes such as COVID-19. The proposed methods is based on online Long Short-Term Memory (LSTM) recurrent neural network. To speed up the learning process during concept changes and improve prediction accuracy, an ensemble of multiple models with different learning rates is used. The learning rates are updated in realtime to best adapt to the new concept while maintaining the learned information for the prediction.
Conference: Annual Conference of the PHM Society, vol. 12, no. 1, p. 8, 9-13 November 2020
Authors: Y. Du, H. Tu, H. Yu and S. Lukic
Abstract: Distributed secondary control has been widely used in hierarchical control structures, where multiple distributed generators (DGs) need to coordinate to regulate system voltage and frequency. In these systems, consensus algorithms determine the average of a group of dynamic states (e.g. voltages measured by a group of DGs). To be useful, consensus algorithms must be computationally efficient, stable and accurate. In practice, numerous practical implementation challenges significantly affect the consensus equilibrium. In this paper, we quantify the accuracy deviations of the distributed average observer algorithms proposed in the literature to demonstrate the problems with the state-of-the-art distributed averaging techniques. A novel approach is proposed that achieves accurate average tracking in the presence of time-varying communication delays among agents. In our implementation, time synchronization of all distributed controllers is enabled by a novel software platform, called Resilient Information Architecture Platform for the Smart Grid (RIAPS). The proposed distributed average observer is implemented on hardware controllers and its effectiveness is validated in a controller hardware-in-the-loop testbed.
Conference: IEEE Transactions on Smart Grid, 21 February 2020
Authors: J. Xie, C.-C. Liu, M. Sforna, and Y. Xu
Abstract: An agent-based scheme is proposed for distributed underfrequency load shedding (UFLS). The key concept is a consensus weighting protocol (CWP) for agents to reach an agreement. Unlike the well adopted average-consensus protocol (ACP), the proposed CWP enables each agent to converge to its weighted portion of the sum of all initial values. Thus, the proposed CWP is more suitable for the UFLS application, as it allows load buses with a higher level of loading to shed more, rather than reducing by the same average value over all load buses as required by the ACP. Proof of convergence for the proposed CWP is derived and presented in this paper, together with the constraints. For implementation of the multi-agent system (MAS), the monitoring, estimation, and distribution steps are developed. Two study cases and the simulation results are provided to validate the performance of the proposed agent-based UFLS scheme.
Conference: International Journal of Electrical Power & Energy Systems, vol. 117, May 2020
Authors: Y. Du, X. Lu, H. Tu, J.Wang, S. Lukic
Abstract: In contrast to conventional static microgrids (MGs), MGs with dynamic and adjustable territories (i.e., dynamic MGs) are proposed and implemented in this paper. Dynamic MGs are commonly dominated by grid-forming inverters and nested in unbalanced distribution feeders. Unlike balanced systems where only positive-sequence components exist, proper operation of unbalanced dynamic MGs presents additional challenges. A distributed secondary control strategy is developed in this study for distributed generators (DGs) interfaced with gridforming inverters in unbalanced dynamic MGs by providing coordinated regulations on both positive- and negative-sequence system models. System frequency and voltage are under constant regulation, along with voltage unbalance (VU) management for multiple critical load buses (CLB). The proposed control strategy enables seamless system transition during unbalanced dynamic MGs reconfiguration, and guarantees proportional positive- and negative-sequence power sharing among connected DGs with respect to system topology variation. Detailed controller designs are provided and stability analyses are derived. The proposed control strategy is fully implemented in hardware controllers and validated on a Hardware-in-the-Loop (HIL) MG testbed.
Journal: IEEE Journal of Emerging and Selected Topics in Power Electronics, August 21, 2019, pg 1
Authors: Y. Zhang, S. Eisele, A. Dubey, A. Laszka and A. Srivastava
Abstract: Transactive energy systems (TES) are emerging as a transformative solution for the problems that distribution system operators face due to an increase in the use of distributed energy resources and rapid growth in scalability of managing active distribution system (ADS). On the one hand, these changes pose a decentralized power system controls problem, requiring strategic control to maintain reliability and resiliency for the community and for the utility. On the other hand, they require robust financial markets while allowing participation from diverse prosumers. To support computing requirements of TES with required flexibility while preserving privacy and security, a distributed software platforms is required. In this paper, we enable the study and analysis of security concerns by developing Transactive Energy Security Simulation Testbed (TESST), a TES testbed for simulating various cyber attacks. In this work, the testbed is used for TES simulation with centralized clearing market, highlighting weaknesses in a centralized system. Additionally, we present a blockchain enabled decentralized market solution supported by distributed computing for TES, which on one hand can alleviate some of the problems we identify, but on the other hand may introduce newer issues. Future study of these differing paradigms is necessary and will continue as we develop our security simulation testbed.
Conference: 7th Workshop on Modeling and Simulation of Cyber-Physical Energy Systems (MSCPES), Montreal, Canada, April, 2019
Authors: Y. Du, H. Tu, S. Lukic, D. Lubkeman, A. Dubey, and G. Karsai
Abstract: Microgrids (MGs) are ideally suited for distributed control solutions. However, implementation and validation of the developed distributed control algorithms are quite challenging. In this paper we propose a Controller Hardware-in-the-Loop (CHIL) platform for MG distributed control applications that satisfy the requirements of IEEE Std. 2030.7 for MG control systems.We describe two main features of the proposed platform: 1) a software platform that enables the implementation of control algorithms that have been developed analytically and 2) a real-time MG testbed that replicates practical MG operation environment by using real-time communication network and grid solutions. Implementation and validation of a distributed MG synchronization operation control strategy are used to demonstrate the performance of the proposed CHIL platform.
Conference: 2018 IEEE Electronic Power Grid (eGRID), Charleston, SC, November 2018
Authors: H. Tu, Y. Du, Y. Hui, S. M. Lukic, M. Metelko, P. Volgyesi, A. Dubey, and G. Karsai
Abstract: To maintain a stable, flexible and economic operation of a microgrid, hierarchical control architecture consisting of primary, secondary and tertiary control is proposed. However, the differences in dynamics of microgrid, bandwidths of control levels and speed of communication channels make it difficult to comprehensively validate the performance of the hierarchical control schemes. In this paper we propose a hardware-in-theloop real-time testbed for microgrid hierarchical control. The proposed testbed can be used to validate control performance under different microgrid operating modes (grid-tied or islanded), different primary control schemes (current or voltage mode) and different secondary control approaches (centralized or distributed). The integration of industry-grade hardware that runs primary and secondary control into the testbed allows for complete emulation of microgrid operation, and facilitates the study of the effects of measurement noise, sampling and communication delays.
Conference: 10th Anniversary IEEE Energy Conversion Congress and Exposition (ECCE 2018), Portland, Oregon, September, 2018
Authors: V. V. G. Krishnan, S.Gopal, R.Liu, Z.Nie, A.Srivastava and D.Bakken
Abstract: Remedial Action Schemes (RAS) provide automatic control action with high impact on system performance. In order to improve the resilience of the RAS against any single node failure and to guarantee the secured and reliable operation of the power systems, distributed implementations of the RAS is researched upon. The input data to such a distributed RAS must be of high quality. In addition, RAS operation must be fast. Traditional centralized state estimation, which feeds data to RAS is slow and cannot meet the requirements of RAS. New approach needs to be developed to provide the fast and accurate data to RAS. In order to solve this problem, distributed state estimation is developed as an alternative strategy to feed data to the RAS. This paper discusses the implementation of Distributed Linear State Estimation (DLSE) in a decentralized platform called Resilient Information Architecture Platform for Smart Grid (RIAPS). The DLSE algorithm is fully implemented in RIAPS platform and validated on a real-time testbed consisting of Real Time Digital Simulator, Phasor Measurement Units and BeagleBones. The effectiveness of the proposed approach is validated through online simulations on IEEE 14-bus test system under various cyber failures.
Conference: IEEE Power and Energy Society General Meeting, Portland, OR, USA, August 2018
Authors: Y. Du, H. Tu, S. M. Lukic, A. Dubey and G. Karsai
Abstract: To seamlessly reconnect an islanded microgrid to the main grid, voltage phasors on both sides of the point of common coupling need to be synchronized before the main relay closes. In this paper, a distributed control strategy is proposed for microgrid synchronization operation. The proposed controller design utilizes pinning-based consensus algorithm to avoid system single point of failure. It is able to actively track the main grid frequency, provide a good coordination between frequency and phase regulation and ensure all distributed generations in the system proportionally share the load. Implementation of such distributed algorithm in practice is difficult because it requires mitigation of both distributed computing and power system engineering challenges. In this paper, a novel software platform called RIAPS platform is presented that helps implementing the proposed distributed synchronization strategy in practical hardware controllers. The performance of the controllers are validated using a real-time controller hardware-in-the-loop microgrid testbed.
Conference: 10th Anniversary IEEE Energy Conversion Congress and Exposition (ECCE 2018), Portland, OR, September, 2018
Authors: V. V. G. Krishnan, S. Gopal, R. Liu, A. Askerman, A. K. Srivastava, D. Bakken, and P. Panciatici
Abstract: Integration of Distributed Energy Resources (DER) has been significantly increasing in the electric power grid. One of the predominant renewable energy sources, wind energy, possess a significant challenge for grid operations, due to its intermittency, uncertainity and variability. In changing operating conditions with wind uncertainity, part of wind may need to be curtailed for the safe utilization of the transmission system. In order to minimize the wind power curtailment and to keep the power flow on a transmission line under limits, a cyber resilient Distributed Remedial Action Scheme (DRAS) is developed in this paper. The RAS is formulated as an optimization problem, considering the real power flow constraints of the transmission lines and given wind variability. In this paper, DRAS is developed to operate even with failures in the computing nodes to make it cyber-resilient. Distributed simplex algorithm is used for optimization in the distributed RAS. The DRAS is implemented in a decentralized platform called Resilient Information Architecture Platform for Smart Grid (RIAPS) to enable cyber resiliency of DRAS. The effectiveness of the proposed approach is validated through offline simulations of the New England 39 bus system and online simulations of IEEE 14 bus test system. A cyberphysical test bed utilizing Real Time Digital Simulator (RTDS), Phasor Measurement Units (PMUs), and BeagleBones has been used for the online simulation and validation of the developed cyber-resilient RAS.
Journal: IEEE Transactions on Industry Applications (early access), September 03, 2018
Authors: Y. Du, H. Tu, and S. M. Lukic
Abstract: To seamlessly transition a microgrid (MG) from islanded to grid-connected mode, it is necessary to synchronize the magnitude, frequency, and phase of the MG voltage to the voltage of the main grid. In this paper, we present a distributed control strategy to achieve synchronized operation of an islanded MG supported by multiple controllable distributed generators (DGs). The proposed method utilizes pinning-based consensus algorithm to ensure explicit coordination between magnitude, frequency and phase angle regulation, while ensuring proportional power sharing. System frequency is regulated by all the DGs in proportion to their capacity, while a selected DG eliminates the phase and magnitude regulation errors. Controller design criteria is based on small-signal stability analysis. The proposed control strategy is implemented in hardware controllers and its effectiveness is demonstrated using a real-time hardware-in-the-loop MG testbed.
Journal: IEEE Transactions on Smart Grid (early access), July 31, 2018, page 1-1
Authors: H. Tu, Y. Du, H. Yu, S. Lukic, P. Volgyesi, M. Metelko, A. Dubey, G. Karsai
Abstract: To integrate DC distributed generation (DG) with micro-source into the existing AC grid, a DC distribution bus can be used to couple on-site photovoltaics (PV), battery energy storage systems (BESS), and DC loads. If the converters connected to the DC bus are interleaved, the DC bus capacitor size could be minimized. In this paper, we propose an interleaving algorithm for multi-converter systems to minimize the current harmonics at switching frequency on the DC bus. The proposed algorithm is implemented using Resilient Information Architecture Platform for Smart Grid (RIAPS) platform. Hardware-in-the-Loop (HIL) simulation results based on Opal-RT are presented to validate its performance. The influence of synchronization frequency on the proposed algorithm are also considered.
Conference: IEEE 9th International Symposium on Power Electronics for Distributed Generation Systems (PEDG 2018), Charlotte, NC, June 25-28, 2018
Authors: Y. Du, H. Tu, S. Lukic, D. Lubkeman, A. Dubey, G. Karsai
Abstract: Maintaining voltage and frequency stability in an islanded microgrid is challenging, due to the low system inertia. In addition, islanded microgrids have limited generation capability, requiring that all DGs contribute proportionally to meet the system power consumption. This paper proposes a distributed control algorithm for optimal apparent power utilization in islanded microgrids. The developed algorithm improves system apparent power utilization by maintaining proportional power sharing among DGs. A decentralized platform called Resilient Information Architecture Platform for Smart Systems (RIAPS) is introduced that runs on processors embedded within the DGs. The proposed algorithm is fully implemented in RIAPS platform and validated on a real-time microgrid testbed.
Conference: IEEE PES Transmission and Distribution Conference and Exposition (T&D 2018), Denver, CO, USA, April, 2018
Authors: V. V. G. Krishnan, S.Gopal, Z.Nie and A.Srivastava
Abstract: The power grid is becoming increasingly complex with multi-domain and multi-physics interaction given enhanced automation, increasing DERs, active distribution system and push for resiliency. The centralized control for such a complex system will be slow, non-scalable and prone to failures. The local controllers for such system will be non-optimal, hard coded and not fault-tolerant. The preferred control architecture for such system will be distributed architecture as it is relatively fast, scalable and robust. The distributed architecture supports the power grid monitoring and control for enhanced resiliency and reliability, but need to be tested and validated before field implementation. This paper presents a cyber-power testbed architecture to validate distributed applications in the power grid. Distributed Remedial Action Scheme (DRAS) algorithm is validated using the testbed as an example distributed control testcase. DRAS has been implemented using a distributed computing platform called Resilient Information Architecture Platform for Smart Grid (RIAPS). Developed cyber-power testbed utilizes Real Time Digital Simulator, Phasor Measurement Units and CISCO FOG routers with RIAPS platform. The testbed is validated through online simulations of IEEE 14-bus test system with distributed control under various cyber failures for satisfactory response.
Conference: Workshop on Modeling and Simulation of Cyber-Physical Energy Systems, CPSWeek, Porto, Portugal, April 2018
Authors: V. V. G. Krishnan, R. Liu, A. Askerman, A. Srivastava, D. Bakken, P. Panciatici
Abstract: With the development of the smart grid and the advancement in the renewable energy technology, integration of Distributed Energy Resources (DER) has significantly increased in the electric power grid. One of the predominant renewable energy sources, wind energy, possess a significant challenge for grid operations, due to its intermittency and variability. In some operating conditions, part of wind has to be curtailed for the safe utilization of the transmission system. In order to minimize the wind power curtailment and to keep the power flow on a transmission line under limits, a cyber resilient Remedial Action Scheme (RAS) is developed in this paper. The RAS is formulated as an optimization problem, considering the real power flow constraints of the transmission lines and voltage constraints of the transmission buses. RAS is developed to operate even under limited failures in the computing nodes to make it cyber-resilient RAS. The effectiveness of the proposed approach is validated through offline simulations of the New England 39 bus system and online simulations of IEEE 14 bus test system. A cyber-physical test bed utilizing Real Time Digital Simulator (RTDS), Phasor Measurement Units (PMUs), and a communication emulator (NS-3) has been used for the online simulation and validation of the developed cyber-resilient RAS.
Conference: 2017 IEEE Industry Applications Society (IAS) Annual Meeting, Cincinnati, OH, USA, IEEE, October 1-5, 2017
Authors: J. Xie, C.-C. Liu, and M. Sforna
Abstract: A distributed underfrequency load shedding (UFLS) scheme is proposed as a last resort to mitigate the frequency decline. In the agent-based scheme, Paxos and average-consensus protocols are utilized by agents to reach an agreement. The monitoring, estimation, and distribution steps are presented in detail for implementation of the multi-agent system (MAS). Simulation results are provided to validate the performance of the proposed agent-based UFLS scheme, which is being implemented as a demonstrative application of the RIAPS (Resilient Information Architecture Platform for the Smart grid).
Conference: 2017 19th International Conference on Intelligent System Application to Power Systems (ISAP), San Antonio, TX, USA, IEEE, September 17-20, 2017
Authors: Y. Du, H. Tu, S. Lukic, D. Lubkeman, A. Dubey, G. Karsai
Abstract: Formation of microgrids have been proposed as a solution to improve grid reliability, and enable smoother integration of renewables into the grid. Microgrids are sections of the grid that can operate in isolation from the main power system. Maintaining power balance within an islanded microgrid is a challenging task, due to the low system inertia, which requires complex control to maintain stable and optimized operation. Many studies have demonstrates feasible distributed microgrid controllers that can maintain microgrid stability in grid connected and islanded modes. However, there is little emphasis on how to implement these distributed algorithms on a computational platform that allows for fast and seamless deployment. This paper introduces a decentralized software platform called Resilient Information Architecture Platform for Smart Systems (RIAPS) that runs on processors embedded with the microgrid component. As an example, we describe the implementation of a distributed microgrid secondary control and resynchronization algorithms on RIAPS platform. The controller developed on RIAPS platform is validated on a real-time microgrid testbed.
Conference: 2017 North American Power Symposium (NAPS), Morgantown, WV, IEEE, September 17-19, 2017
Authors: Jing Xie, and Chen-Ching Liu
Abstract: The number of distributed energy components and devices continues to increase globally. As a result, distributed control schemes are desirable for managing and utilizing these devices, together with the large amount of data. In recent years, agent-based technology becomes a powerful tool for engineering applications. As a computational paradigm, multi-agent systems (MASs) provide a good solution for distributed control. In this paper, MASs and applications are discussed. A state-of-the-art literature survey is conducted on the system architecture, consensus algorithm, and multi-agent platform, framework, and simulator. In addition, a distributed under-frequency load shedding scheme is proposed using the MAS. Simulation results for a case study are presented. The future of MASs is discussed in the conclusion.
Publication: Journal of International Council on Electrical Engineering, Volume 7, Issue 1, pp. 188-197, 07/2017
Authors: R. Liu, A. Srivastava, A. Askerman, D. Bakken and P. Panciatici
Abstract: Intermittency of wind energy pose a great challenge for power system operation and control. Wind curtailment might be necessary at certain operating condition to keep the line flow within limit. Remedial Action Scheme (RAS) offers quick control action mechanism to keep reliability and security of the power system operation with high wind energy integration. In this paper, a new RAS is developed to maximize the wind energy integration without compromising the security and reliability of the power system based on a specific utility requirements. A new Distributed Linear State Estimation (DLSE) is also developed to provide the fast and accurate input data for the proposed RAS. A distributed computational architecture is designed to guarantee the robustness of cyber system to support RAS and DLSE implementation. The proposed RAS and DLSE is validated using modified IEEE-118 Bus system. Simulation results demonstrate the satisfactory performance of the DLSE and effectiveness of RAS.
Conference: 2016 IEEE Industry Applications Society (IAS) Annual Meeting, Portland, Oregon, October 2-6, 2016
Journal: IEEE Transactions on Industry Applications, Volume 53, Issue 6, ISSN 0093-9994, Nov-Dec 2017, pp. 5915-5926, published 11/01/17
Authors: S. Eisele, T. Eghtesad, K. Campanelli, P. Agrawal, A. Laszka and A. Dubey
Abstract: Power grids are evolving at an unprecedented pace due to the rapid growth of distributed energy resources (DER) in communities. These resources are very different from traditional power sources as they are located closer to loads and thus can significantly reduce transmission losses and carbon emissions. However, their intermittent and variable nature often results in spikes in the overall demand on distribution system operators (DSO). To manage these challenges, there has been a surge of interest in building decentralized control schemes, where a pool of DERs combined with energy storage devices can exchange energy locally to smooth fluctuations in net demand. Building a decentralized market for transactive microgrids is challenging because even though a decentralized system provides resilience, it also must satisfy requirements like privacy, efficiency, safety, and security, which are often in conflict with each other. As such, existing implementations of decentralized markets often focus on resilience and safety but compromise on privacy. In this paper, we describe our platform, called TRANSAX, which enables participants to trade in an energy futures market, which improves efficiency by finding feasible matches for energy trades, enabling DSOs to plan their energy needs better. ...
Journal: ACM Transactions on Cyber-Physical Systems, Vol. 5, No.1, Article No: 8, Dec 2020
Authors: S. Eisele, A. Laszka, D. Schmidt and A. Dubey
Abstract: Power grids are undergoing major changes due to rapid growth in renewable energy and improvements in battery technology. Prompted by the increasing complexity of power systems, decentralized solutions are emerging that arrange local communities into transactive microgrids. This paper addresses the problem of implementing transactive energy mechanisms in a distributed setting, providing both privacy and safety. Specifically, we design and implement an automated auction and matching system that ensures safety (e.g., satisfaction of line capacity constraints), preserves privacy, and promotes local trade and market efficiency for transactive energy systems. This design problem is challenging because safety, market efficiency, and privacy are competing objectives. We implement our solution as a decentralized trading platform built on blockchain technology and smart contracts. To demonstrate the viability of our platform, we analyze the results of experiments with dozens of embedded devices and energy production and consumption profiles using an actual dataset from the transactive energy domain.
Article: Frontiers in Blockchain, Dec 2020
Authors: S. Eisele, C. Barreto, A. Dubey, X. Koutsoukos, T. Eghtesad, A. Laszka and A. Mavridou
Abstract: The emergence of blockchains and smart contracts has renewed interest in electrical cyberphysical systems, especially transactive energy systems. To address the associated challenges, we present TRANSAX, a blockchain-based transactive energy system that provides an efficient, safe, and privacy-preserving market built on smart contracts.
Journal: IEEE Computer, Vol. 53, Issue. 9, Sep 2020
Authors: A. Laszka, S. Eisele, A. Dubey, G. Karsai, and K. Kvaternik
Abstract: Power grids are undergoing major changes due to rapid growth in renewable energy and improvements in battery technology. Prompted by the increasing complexity of power systems, decentralized IoT solutions are emerging, which arrange local communities into transactive microgrids. The core functionality of these solutions is to provide mechanisms for matching producers with consumers while ensuring system safety. However, there are multiple challenges that these solutions still face: privacy, trust, and resilience. The privacy challenge arises because the time series of production and consumption data for each participant is sensitive and may be used to infer personal information. Trust is an issue because a producer or consumer can renege on the promised energy transfer. Providing resilience is challenging due to the possibility of failures in the infrastructure that is required to support these market based solutions. In this paper, we develop a rigorous solution for transactive microgrids that addresses all three challenges by providing an innovative combination of MILP solvers, smart contracts, and publish-subscribe middleware within a framework of a novel distributed application platform, called Resilient Information Architecture Platform for Smart Grid. Towards this purpose, we describe the key architectural concepts, including fault tolerance, and show the trade-off between market efficiency and resource requirements.
Conference: The 24th Internaltional Conference on Parallel and Distributed Systems (IEEE ICPADS 2018), Sentosa, Singapore, December, 2018
Authors: S. Eisele, A. Laszka, A. Mavridou, and A. Dubey
Abstract: Internet of Things and data sciences are fueling the development of innovative solutions for various applications in Smart and Connected Communities (SCC). These applications provide participants with the capability to exchange not only data but also resources, which raises the concerns of integrity, trust, and above all the need for fair and optimal solutions to the problem of resource allocation. This exchange of information and resources leads to a problem where the stakeholders of the system may have limited trust in each other. Thus, collaboratively reaching consensus on when, how, and who should access certain resources becomes problematic. This paper presents SolidWorx, a blockchain-based platform that provides key mechanisms required for arbitrating resource consumption across different SCC applications in a domain-agnostic manner. For example, it introduces and implements a hybrid-solver pattern, where complex optimization computation is handled off-blockchain while solution validation is performed by a smart contract. To ensure correctness, the smart contract of SolidWorx is generated and verified.
Conference: IEEE International Conference on Blockchain (Blockchain-2018), Halifax, Canada, July 2018
Authors: A. Laszka, A. Dubey, S. Eisele, M. Walker, K. Kvaternik
Abstract: Power grids are undergoing major changes due to rapid growth in renewable energy and improvements in battery technology. Prompted by the increasing complexity of power systems, decentralized IoT solutions are emerging, which arrange local communities into transactive microgrids. We address the problem of implementing transactive energy mechanisms in a distributed setting, providing both privacy and safety. Specifically, we design and implement an automated auction and matching system that ensures safety (i.e. satisfaction of line capacity constraints), preserves privacy, and promotes local trade and market efficiency for IoT-based transactive energy systems. This design problem is challenging because safety, market efficiency, and privacy are competing objectives. We implement our solution as a decentralized IoT-based trading platform, which is built on blockchain technology and smart contracts. To demonstrate the feasibility of our platform, we perform experiments with dozens of embedded devices and energy production and consumption profiles from a real dataset.
Conference: ACM/IEEE IoTDI 2018, Orlando, FL, April 17-20, 2018
Authors: J. Bergquist, A. Laszka, M. Sturm, and A. Dubey
Abstract: Transactive microgrids are emerging as a transformative solution for the problems faced by distribution system operators due to an increase in the use of distributed energy resources and a rapid acceleration in renewable energy generation, such as wind and solar power. Distributed ledgers have recently found widespread interest in this domain due to their ability to provide transactional integrity across decentralized computing nodes. However, the existing state of the art has not focused on the privacy preservation requirement of these energy systems -- the transaction level data can provide much greater insights into a prosumer's behavior compared to smart meter data. There are specific safety requirements in transactive microgrids to ensure the stability of the grid and to control the load. To fulfil these requirements, the distribution system operator needs transaction information from the grid, which poses a further challenge to the privacy-goals. This problem is made worse by requirement for off-blockchain communication in these networks. In this paper, we extend a recently developed trading workflow called PETra and describe our solution for communication and transactional anonymity.
Conference: 1st Workshop on Scalable and Resilient Infrastructures for Distributed Ledgers (SERIAL 2017), Las Vegas, Nevada, USA, December 11-15, 2017
Authors: M. Walker, A. Dubey, A. Laszka, and D. Schmidt
Abstract: With the advent of blockchain-enabled IoT applications, there is an increased need for related software patterns, middleware concepts, and testing practices to ensure adequate quality and productivity. IoT and blockchain each provide different design goals, concepts, and practices that must be integrated, including the distributed actor model and fault tolerance from IoT and transactive information integrity over untrustworthy sources from blockchain. Both IoT and blockchain are emerging technologies and both lack codified patterns and practices for development of applications when combined. This paper describes PlaTIBART, which is a platform for transactive IoT blockchain applications with repeatable testing that combines the Actor pattern (which is a commonly used model of computation in IoT) together with a custom Domain Specific Language (DSL) and test network management tools. We show how PlaTIBART has been applied to develop, test, and analyze fault-tolerant IoT blockchain applications.
Conference: Workshop on Middleware and Applications for the Internet of Things (M4IoT) 2017, Las Vegas, Nevada, USA, December 11, 2017
Authors: A. Laszka, A. Dubey, M. Walker, and D. Schmidt
Abstract: Power grids are undergoing major changes due to rapid growth in renewable energy resources and improvements in battery technology. While these changes enhance sustainability and efficiency, they also create significant management challenges as the complexity of power systems increases. To tackle these challenges, decentralized Internet-of-Things (IoT) solutions are emerging, which arrange local communities into transactive microgrids. Within a transactive microgrid, “prosumers” (i.e., consumers with energy generation and storage capabilities) can trade energy with each other, thereby smoothing the load on the main grid using local supply. It is hard, however, to provide security, safety, and privacy in a decentralized and transactive energy system. On the one hand, prosumers’ personal information must be protected from their trade partners and the system operator. On the other hand, the system must be protected from careless or malicious trading, which could destabilize the entire grid. This paper describes Privacypreserving Energy Transactions (PETra), which is a secure and safe solution for transactive microgrids that enables consumers to trade energy without sacrificing their privacy. PETra builds on distributed ledgers, such as blockchains, and provides anonymity for communication, bidding, and trading.
Conference: The 7th International Conference on the Internet of Things (IoT 2017), Linz, Austria, ACM, October 22-25, 2017
The information, data or work presented herein was funded in part by the Advanced Research Projects Agency - Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000666. The views and opinions of the authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.