Power systems have seen many changes over the last decade including the increased penetration of renewable generation, electric vehicles and new technologies for sensing, communication and control of a Smart Grid. The most significant impact of these changes are being felt at the consumer level. The ability for consumers and end devices to buy and sell energy and related services in a dynamic and interactive manner is expected to create a transactive energy market as highlighted in the Dec 2014 report of GridWise Alliance. Modeling and preparing the physical system to respond to the somewhat unpredictable behavior of active consumers over a cyber-infrastructure will be critical for maintaining grid reliability. Understanding the impact of such active consumers on the operational and business policies of the distribution utility requires advances in core system science that spans the areas of power engineering, economics, statistical signal processing, game theory, distributed control, multi-agent systems and cyber security. In conjunction with industrial partners, Westar Energy (the largest electric company in Kansas) and Kansas City Power and Light, the PIs plan to develop an architecture that requires little change to the existing investment in power distribution systems while allowing for the dynamic, adaptive control required to integrate active consumers with current and future combinations of high-variability distributed power sources, such as Photo-voltaic (PV) generators and storage batteries. In contrast to prior related efforts that primarily focus on demand response and distributed generation management with a single home/user centric approach, the proposed approach takes a holistic system perspective that includes cumulative modeling of multiple stochastic active consumers and the cyber infrastructure over which they may interact. Specific research thrusts include: (1) a general, extensible, and secure cyber architecture based on holonic multi-agent principles that provides a pathway to the emerging area of transactive energy market in power distribution systems, but also provides foundation for other engineered systems with active consumers; (2) new analytical insights into generalized stochastic modeling of consumer response to real]time price of electricity and the impact of such active consumers on grid reliability and security, and (3) novel methodology for comprehensive distributed control and management of power distribution systems with active consumers and high penetration of distributed renewable resources. Active consumers are an integral part of the Smart City vision where cyber systems are integrated into the transportation, energy, healthcare and biomedical, and critical infrastructure systems. Successful completion of this project will result in modeling, control, analysis and simulation architectures for all such active consumer driven CPS domains. The resulting gains in operating efficiency, economics, reliability and security will result in overall welfare for the society.

Many practical systems such as smart grid, unmanned aerial vehicles (UAVs) and robotic networks can be categorized as cyber physical systems (CPS). A typical CPS consists of physical dynamics, sensors, communication network and controllers. The communication network is of key importance in CPS, since it mimics the nerve system in the human body. Hence, it is critical to study how the communication network in CPS should be analyzed and designed. Essentially, communications stem from the uncertainty of system under consideration; random perturbations increase the system uncertainty, which is reduced by the control actions in CPS. It is well known that entropy is a measure of system uncertainty. A unified framework of entropy is used for CPS, in which random perturbations create entropy while communications and controls provide negative entropy to compensate the entropy generation. The intellectual merits are the novel framework of entropy for bridging the communications and control in CPS and the new design criterion based on the entropy of system state for CPS. The project's broader significance and importance are the education of various levels of students, the dissemination of results to public, and the impact on everyday life such as the improved agility and robustness of power grids. This project applies the framework of entropy to study the interdependencies of communications and control, thus facilitating the analysis and design of communications in CPS. The following tasks are tackled in the project: (a) Entropy Flow Based Communication Capacity Analysis in which communications in CPS is analyzed by studying the entropy fields in the physical dynamics, thus providing an estimation on the scale (bits/second) of communication capacity budget; (b) Communication Network Topology Design in which the design of the network topology (either physical or logical) is tackled through both optimization-based or heuristic approaches; (c) Online Network Resource Scheduling which refines the network resource scheduling during the operation using both optimization-based and heuristic approaches, within the framework of entropy fields; (d) Hardware Emulation Testbed which delivers a co-simulation testbed based on real time digital power simulator (RTDS) and a communication simulator, in the context of smart grids. Based on the research, new courses are developed. K-12 outreach and various levels of undergraduate/graduate educations are incorporated into the research.

Smart grid includes two interdependent infrastructures: power transmission and distribution network, and the supporting telecommunications network. Complex interactions among these infrastructures lead to new pathways for attack and failure propagation that are currently not well understood. This innovative project takes a holistic multilevel approach to understand and characterize the interdependencies between these two infrastructures, and devise mechanisms to enhance their robustness. Specifically, the project has four goals. The first goal is to understand the standardized smart grid communications protocols in depth and examine mechanisms to harden them. This is essential since the current protocols are notoriously easy to attack. The second goal is to ensure robustness in state estimation techniques since they form the basis for much of the analysis of smart grid. In particular, the project shall exploit a steganography-based approach to detect bad data and compromised devices. The third goal is to explore trust-based attack detection strategies that combine the secure state estimation with power flow models and software attestation to detect and isolate compromised components. The final goal is to study reconfiguration strategies that combine light-weight prediction models, stochastic decision processes, intentional islanding, and game theory techniques to mitigate the spreading of failures and the loss of load. A unique aspect of smart grid security that will be studied in this project is the critical importance of timeliness, and thus a tradeoff between effectiveness of the mechanisms and the overhead introduced. The project is expected to provide practical techniques for making the smart grid more robust against failures and attacks, and enable it to recover from large scale failures with less loss of capacity. The project will also train students in the multidisciplinary areas of power systems operation and design, networking protocols, and cyber-physical security.

The wide-area measurement systems technology using Phasor Measurement Units (PMUs) has been regarded as the key to guaranteeing stability, reliability, state estimation, and control of next-generation power systems. However, with the exponentially increasing number of PMUs, and the resulting explosion in data volume, the design and deployment of an efficient wide-area communication and computing infrastructure is evolving as one of the greatest challenges to the power system and IT communities. The goal of this NSF CPS project is to address this challenge, and construct a massively deployable cyber-physical architecture for wide-area control that is fast, resilient and cost-optimal (FRESCO). The FRESCO grid will consist of a suite of optimal control algorithms for damping oscillations in power flows and voltages, implemented on top of a cost-effective and cyber-secure distributed computing infrastructure connected by high-speed wide-area networks that are dynamically programmable and reconfigurable. The value of constructing FRESCO is twofold (1) If a US-wide communication network capable of transporting gigabit volumes of PMU data for wide-area control indeed needs to be implemented over the next five years then power system operators must have a clear sense of how various forms of delays, packet losses, and security threats affect the stability of these control loops. (2) Moreover, such wide-area communication must be made economically feasible and sustainable via joint decision-making processes between participating utility companies, and testing how controls can play a potential role in facilitating such economics. Currently, there is very limited insight into how the PMU data transport protocols may lead to a variety of such delay patterns, or dictate the economic investments. FRESCO will answer all of these questions, starting from small prototypical grid models to those with tens of thousands of buses. Our eventual goal will be to make FRESCO fully open-source for Transition to Practice (TTP). We will work with two local software companies in Raleigh, namely Green Energy Corporation and Real-Time Innovations, Inc. to develop a scalable, secure middleware using Data-Distribution Service (DDS) technology. Thus, within the scope of the project, we also expect to enrich the state-of-the-art cloud computing and networking technologies with new control and management functions. From a technical perspective, FRESCO will answer three main research questions. First, can wide-area controllers be co-designed in sync with communication delays to make the closed-loop system resilient and delay-aware, rather than just delay-tolerant This is particularly important, as PMU data, in most practical scenarios, will have to be transported over a shared resource, sharing bandwidth with other ongoing applications, giving rise to not only transport delays, but also significant delays due to queuing and routing. Advanced ideas of arbitrated network control designs will be used to address this problem. The second question we address is for cost. Given that there are several participants in this wide-area control, how much is each participant willing to pay in sharing the network cost with others for the sake of supporting a system-wide control objective compared to its current practice of opting for selfish feedback control only Ideas from cooperative game theory will be used to investigate this problem. The final question addresses security how can one develop a scientific methodology to assess risks, and mitigate security attacks in wide-area control? Statistical and structural analysis of attack defense modes using Bayesian and Markov models, game theory, and discrete-event simulation will be used to address this issue. Experimental demos will be carried out using the DETER-WAMS network, showcasing the importance of cyber-innovation for the sustainability of energy infrastructures. Research results will be broadcast through journal publications, and jointly organized graduate courses between NCSU, MIT and USC.