Chen-Ching Liu

Virginia Tech (Virginia Polytechnic Institute and State University) | VT · Power and Energy Center

Machine learning (ML)-based intrusion detection system (IDS) approaches have been significantly applied and advanced the state-of-the-art system security and defense mechanisms. In smart grid computing environments, security threats have been significantly increased as shared networks are commonly used, along with the associated vulnerabilities. Ho...

The increasing penetration of electric vehicles (EVs) brings new flexibility in power grid operation. As EVs serve the main purpose of transportation, EV owners will charge their vehicles based on their driving patterns. Given the clustering charging behavior, uncontrolled charging can burden the distribution grid, increasing system operation costs...

The active participation of demand-side flexible resources in the wholesale market price formation and load dispatch process is crucial to encouraging demand-side participation. This calls for a joint supply-demand coordination mechanism to fully take advantage of the flexible resources in distribution systems, including distributed energy resource...

In [1] , during typesetting process, some mistakes were made in symbols. The errors and corrections are listed below. The errors are highlighted in blue. The corrections are highlighted in red.

A major outage in the electricity distribution system may affect the operation of water and natural gas supply systems, leading to an interruption of multiple services to critical customers. Therefore, enhancing resilience of critical infrastructures requires joint efforts of multiple sectors. In this paper, a distribution system service restoratio...

Fast inverter control is a desideratum towards the smoother integration of renewables. Adjusting inverter injection setpoints for distributed energy resources can be an effective grid control mechanism. However, finding such setpoints optimally requires solving an optimal power flow (OPF), which can be computationally taxing in real time. This work...

An islanded microgrid is cyber-physical system, and the control relies on the communication system significantly. Improper parameters of the cyber system can result in instability of a microgrid system. To evaluate the impact of a networked control system on control performance, a cyber model is developed to represent data acquisition periods and c...

Cryptographic schemes are often deployed in microgrids to protect communication security. However, most existing schemes widely used in microgrids cannot ensure forward secrecy and non-repudiation under key leakage and dishonest insiders. Although some existing cryptographic techniques can theoretically overcome these vulnerabilities, their computa...

Fast inverter control is a desideratum towards the smoother integration of renewables. Adjusting inverter injection setpoints for distributed energy resources can be an effective grid control mechanism. However, finding such setpoints optimally requires solving an optimal power flow (OPF), which can be computationally taxing in real time. Previous...

Distributed energy resource management systems (DERMS) are increasingly deployed to manage potential adverse impacts of DERs on distribution feeder voltages. However, communication channels used by DERMS controllers, along with the unmanned substations where they are deployed, provide a target for cyber attackers to cause severe voltage disturbance...

A major outage in the electricity distribution system may affect the operation of water and natural gas supply systems, leading to an interruption of multiple services to critical customers. Therefore, enhancing resilience of critical infrastructures requires joint efforts of multiple sectors. In this paper, a distribution system service restoratio...

The increasing deployment of distributed energy resources (DERs) and microgrids benefits power grids by improving system resilience. In a resilience mode without the utility system, the distribution grid relies on DERs to serve critical load. In such a severe event with multiple faults on the distribution feeders, actuation of various protective de...

Increasing penetrations of distributed energy resources (DERs) and responsive loads (RLs) in the electric power distribution systems calls for a mechanism for joint supply-demand coordination. Recently, several transactive/bilateral coordination mechanisms have been proposed for the distribution-level coordination of flexible resources. Implementin...

Resiliency of a distribution system can be enhanced by efficient restoration of critical load following a major outage. Existing models include optimization approaches that consider available information without incorporating the inherent asynchrony of data arrival during execution of the restoration plan. Failure to consider the asynchronous natur...

The Information and Communications Technology (ICT) for control and monitoring of power systems is a layer on top of the physical power system infrastructure. The cyber system and physical power system components form a tightly coupled Cyber–Physical System (CPS). Sources of vulnerabilities arise from the computing and communication systems of the...

Threats of cyberattacks targeting the electric power grid have been increasing in recent years. The consequence of cyber incidents on the power grid includes equipment damage, cascading events, large-scale power outages, and disruption of market functions. Government and industry have made a significant effort to strengthen the protection of the po...

Information and Communications Technology (ICT) supports the development of novel control and communication functions for monitoring, operation, and control of power systems. However, the high-level deployment of ICT also increases the risk of cyber intrusions for Supervisory Control And Data Acquisition (SCADA) systems. Attackers can gain access t...

The increasing penetration of proactive agents in electric power distribution systems calls for mechanisms to coordinate their trading activities. The commonly employed centralized and distributed methods for supply-demand coordination are not only limited by hardware requirements but also restrictive for active participation of the market agents....

Hierarchical state estimation (HSE) is often deployed to evaluate the states of an interconnected power system from telemetered measurements. By HSE, each low-level control center (LCC) takes charge of the estimation of its internal states, whereas a trusted high-level control center (HCC) assumes the coordination of boundary states. However, a tru...

Microgrids, consisting of distributed generators (DGs), loads, and energy storage systems, play an important role in future smart grids. In order to evaluate microgrid operations and their dynamic response, it is necessary to develop accurate dynamic models of DGs in microgrids. This paper presents a systematic method to calibrate the model of a sy...

Microgrids can be operated in a utility‐connected mode or an islanded mode in separation with the transmission or distribution system. As major disasters occur, intentional islanding of a microgrid is a possible solution to serve critical loads, within or outside the microgrids, until the utility service is restored. Through a field test, the techn...

The integration of Information and Communications Technology (ICT) enables real-time communication for smart meters to participate in power system operations. However, Advanced Metering Infrastructures (AMI) are vulnerable to cyber attacks. Both utilities and power consumers may become victims of cyber intrusions. In this paper, a two-stage cyber i...

Share Link: https://authors.elsevier.com/a/1a0S6WJH6PGKt ===================== 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...

The rapid escalation in plug-in electric vehicles (PEVs) and their uncoordinated charging patterns pose several challenges in distribution system operation. Some of the undesirable effects include overloading of transformers, rapid voltage fluctuations, and over/under voltages. While this compromises the consumer power quality, it also puts on extr...

The growing number of consumer-grade network-enabled Distributed Energy Resources (DER) installations introduces new attack vectors that could impact grid operations through coordinated attacks. This work presents a cyber-physical model and risk assessment methodology for analyzing the emerging nexus between Internet of Things-based energy devices...

When a fault or a series of faults occur in a distribution network, it is of considerable significance to feeding loads, most importantly critical loads. Although network reconfiguration by switching operations has been usually considered as a relatively low-cost method for load restoration, it alone may not able to restore critical loads under ext...

Conservation voltage reduction(CVR) uses Volt-VAR optimization(VVO) methods to reduce customer power demand by controlling the feeders' voltage control devices. The objective of this paper is to present a VVO approach that controls the systems' legacy voltage control devices and coordinates their operation with smart inverter control. An optimal po...

Operators can now remotely control switches and update the control settings for voltage regulators and distributed energy resources (DERs), thus unleashing the network reconfiguration opportunities to improve efficiency. Aligned to this direction, this work puts forth a comprehensive toolbox of optimization models leveraging the control capabilitie...

The optimal power flow (OPF) problem is a relevant subject for the secure and economic power systems operation. For instance, OPF can be used to reduce the power system technical losses. A reduction in 0.1% in the losses accounts for near 50 billion USD in cost savings. Likewise, OPF can be used along with power production forecast tools, for renew...

Resiliency of distribution systems under extreme operating conditions is critical, especially when the utility is not available. With the large-scale deployment of distributed resources, it becomes possible to restore critical loads with local non-utility resources. Distribution system operators (DSOs) need to determine the critical loads to be res...

This paper presents a two-layer distributed cooperative control method for networked microgrid (NMG) systems, taking into account the proprietary nature of microgrid (MG) owners. The proposed control architecture consists of an MG-control layer and an NMG-control layer. In the MG layer, the primary and distributed secondary controls realize accurat...

Conservation voltage reduction (CVR) uses Volt-VAR optimization (VVO) methods to reduce customer power demand by controlling feeder's voltage control devices. The objective of this paper is to present a VVO approach that controls system's legacy voltage control devices and coordinates their operation with smart inverter control. An optimal power fl...

Increasing penetration of proactive agents, including distributed energy resources (DERs) and responsive loads (RLs), in distribution systems motivates methods to incentivize market participation from demand-side resources. The complexity resulting from large scale integration of proactive agents has challenged the viability of centrally managing g...

As a critical infrastructure, the electric power grid is vulnerable with respect to malicious physical and cyberattacks. This chapter discusses critical vulnerabilities of a smart grid that can be exploited for physical and cyber intrusions. A comprehensive survey is conducted on the state‐of‐the‐art research to enhance the physical and cybersecuri...

When a major outage occurs on a distribution system due to extreme events, microgrids, distributed generators, and other local resources can be used to restore critical loads and enhance resiliency. This paper proposes a decision-making method to determine the optimal restoration strategy coordinating multiple sources to serve critical loads after...

Increasing emphasis on reliability and resiliency call for advanced distribution system restoration (DSR). The integration of grid sensors, remote controls, and distributed generators (DG) brings about exciting opportunities in DSR. In this context, this work considers the task of single-step restoration of a single phase power distribution system....

In recent years, there has been a significant increase in wind power penetration into the power system. As a result, the behavior of the power system has become more dependent on wind power behavior. Supervisory control and data acquisition (SCADA) systems responsible for monitoring and controlling wind farms often have vulnerabilities that make th...

This paper presents a two-layer, four-level distributed control method for networked microgrid (NMG) systems, taking into account the proprietary nature of microgrid (MG) owners. The proposed control architecture consists of a MG-control layer and a NMG-control layer. In the MG layer, the primary and distrib-uted secondary control realize accurate...

When a major outage occurs on a distribution system due to extreme events, microgrids, distributed generators, and other local resources can be used to restore critical loads and enhance resiliency. This paper proposes a decision-making method to determine the optimal restoration strategy coordinating multiple sources to serve critical loads after...

Individual microgrids have proven their ability to provide uninterrupted power to critical end-use load during severe events. Building on the performance of individual microgrids during extreme events, there has been an increasing interest in the operations of network microgrids. By networking microgrids during extreme events, it is possible to sha...

The integration of computing and communication capabilities with the power grid has led to numerous vulnerabilities in the cyber-physical system (CPS). This cyber security threat can significantly impact the physical infrastructure, economy, and society. In traditional IT environments, there are already abundant attack cases demonstrating that unau...

Power system operation considering an increasingly complex cyber infrastructure may be one of the key factors of the next generation power systems. The effective operation of a power system in a massively deployed cyber network environment will be affected by cyber network reliability. Therefore, it is vital not only to understand the operation of...

At Washington State University (WSU), a modern cyber-physical system testbed has been implemented based on an industry grade distribution management system (DMS) that is integrated with remote terminal units (RTUs), smart meters, and a solar photovoltaic (PV). In addition, the real model from the Avista Utilities distribution system in Pullman, WA,...

During a major outage in a secondary network distribution system, distributed generators (DGs) connected to the primary feeders as well as the secondary network can be used to serve critical loads. This paper proposed a resilience-oriented method to determine restoration strategies for secondary network distribution systems after a major disaster....

This paper proposes the new concept of Intelligent Electronic Devices (IEDs) with built-in distributed intrusion detection systems. The proposed IEDs have the capabilities to monitor and detect anomalies and abnormal behaviors of the host system of IED and IEC 61850 based messages, e.g., Sampled Values (SV) and Generic Object Oriented Substation Ev...

Electricity prices vary with time. Stochastic processes are functions of time whose values at different times are random variables. Continuous time stochastic models of commodity prices led to the success of geometric Brownian motion (GBM) in modeling stock prices. This chapter describes some significant features of electricity prices, such as mean...

Microgrids are resources to restore critical loads after a natural disaster, enhancing the resiliency of a distribution network. To deal with stochastic power generated by intermittent energy resources within microgrids, such as wind turbines (WTs) and photovoltaics (PVs), most existing methods require forecast information. However, some microgrids...

Changes in economic, technological, and environmental policies are resulting in a re-evaluation of the dependence on large central generation facilities and their associated transmission networks. Emerging concepts of smart communities/cities are examining the potential to leverage cleaner sources of generation, as well as integrating electricity g...

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, mu...

This paper reviews the state of the art of research and industry practice on demand response and the new methodology of transactive energy. Demand response programs incentivize consumers to align their demand with power supply conditions, enhancing power system reliability and economic operation. The design of demand response programs, performance...

The increased penetration of distributed energy resources (DER) will significantly increase the number of devices that are owned and controlled by consumers and third-parties. These devices have a significant dependency on digital communication and control, which presents a growing risk from cyber-attacks. This study proposes a holistic attack-resi...

A resilience-oriented service restoration method using microgrids to restore critical load after natural disasters is proposed in this paper. Considering the scarcity of power generation resources, the concept of continuous operating time (COT) is introduced to determine the availability of microgrids for critical load restoration and to assess the...

Blackstart capability is essential for power system restoration following a blackout. System restoration planners determine the restoration sequences to provide cranking power from blackstart units (BSUs) to non-blackstart units (NBSUs), pick up critical loads, and energize the necessary transmission paths. This paper proposes a new algorithm for o...

To ensure the secure operation of a power market, transmission networks must maintain an appropriate margin to account for various uncertainties. The uncertainties have increased significantly by the increasing penetration of renewable energy generation. A steady-state security distance (SSD) is an effective security margin that describes the dista...

This chapter explores the many applications of multiagent systems (MAS) with the advantages and disadvantages of the multiagent technology. An MAS is an organization of possibly heterogeneous and self-motivated agents that interact with each other. Agents in an MAS may have conflicting goals or they could coordinate with each other to accomplish a...

This introduction presents an overview of key concepts discussed in the subsequent chapters of this book. The book reviews the applications of power electronics. It is organized into three parts, each dealing with one of the three main topics, high voltage direct current (HVDC), flexible alternating current transmission systems (FACTS), and Artific...

Smart grid is an important application area for artificial intelligence (AI) and computational intelligence (CI), as solutions to complex problems in power system engineering and electric energy markets depend on logic reasoning, heuristic search, perception, and the abilities to handle uncertainties. AI is concerned with decision-making capabiliti...

Cyber intrusions to substations are critical issues to a power grid, which must be defended and mitigated. Essentially, to better understand a cyber intrusion, reconnaissance activities should be modeled. Then, strategies of cyber attacker and defender can be studied, which help to identify substations vulnerable to cyber-attacks. In this paper, a...

The cover image, by Jing Xie et al., is based on the Advanced Review Physical and cyber security in a smart grid environment, DOI: 10.1002/wene.202. Jing Xie would also like to acknowledge Radek Hamza, Martin Bilek, and Marino Sforna for their research efforts that led to this review paper.