Xianyong Feng

Towards a Framework for Cyber Attack Impact Analysis of the Electric Smart Grid

This paper presents a framework for cyber attack impact analysis of a smart grid. We focus on the model synthesis stage in which both cyber and physical grid entity relationships are modeled as directed graphs. Each node of the graph has associated state information that is governed by dynamical system equations that model the physics of the interaction (for electrical grid components) or functionality (for cyber grid elements). We illustrate how cause-effect relationships can be conveniently expressed for both analysis and extension to large-scale smart grid systems.

Towards modelling the impact of cyber attacks on a smart grid

This paper provides an introduction to cyber attack impact analysis in the smart grid and highlights existing research in the field. We present an impact analysis framework where we focus on the model synthesis stage where both cyber and physical grid entity relationships are modelled as directed graphs. Each node of the graph has associated state information that is governed by dynamical system equations that model the physics of the interaction (for electrical grid components) or functionality (for cyber grid elements). We illustrate how cause-effect relationships can be conveniently expressed for both analysis and extension to large-scale smart grid systems.

Multi-Agent System-Based Real-Time Load Management for All-Electric Ship Power Systems in DC Zone Level

All-electric ship power systems have finite generation and include a large portion of dynamic loads and nonlinear loads relative to the total power capacity. Therefore, the load demand and power generation of the system should be matched in real-time. In this paper, a novel multi-agent system-based real-time load management technique is proposed to optimally determine the switch status of loads in DC zones while satisfying the operating constraints of the system in real-time. The multi-agent system cooperative control protocol is developed based on a proposed reduced-order agent model and artificial potential function of the multi-agent system, which aims to maximize the energized loads in the all-electric ship power system. The cooperative controller aims to cooperatively achieve the group objectives that are difficult to reach by centralized controller. Further, simulation results verify the viability and performance of the proposed technique in PSCAD/EMTDC software.

Switched system models for coordinated cyber-physical attack construction and simulation

Effective simulation of large-scale power system disturbances especially those stemming from intentional attack represents an open engineering and research problem. Challenges stem from the need to develop intelligent models of cyber-physical attacks that produce salient disruptions, to appropriately portray meaningful cyber-physical interdependencies, and balance precision, scale and complexity. In this paper, we present a foundation for the development of a class of intelligent cyber-physical attacks that we term coordinated switching attacks. Our approach, based on variable structure systems theory, is amenable to implementation in well known power system simulators. We provide a method to construct such attack models and demonstrate their utility in the simulation of extensive system disturbances. Our results demonstrate the potential for coordinated switch attacks to enable large-scale power system disturbances.

A Multi-Agent System Framework for Real-Time Electric Load Management in MVAC All-Electric Ship Power Systems

All-electric ship power systems include less generation capacity and smaller rotating inertia compared with large power systems. The systems include large portions of nonlinear loads and dynamic loads, which may reduce the stability margin. Moreover, various operational constraints, such as system frequency constraint, motor voltage constraint and dynamic cable constraint, need to be satisfied in operational real time. Further, pulse loads draw very high short-time power in an intermittent way, which may significantly deteriorate the power quality of the system. In this paper, a novel multi-agent system cooperative controller for a medium voltage AC (MVAC) system of all-electric ship power systems is developed to balance load and generation in real time while satisfying systems operational constraints and considering load priorities. The new method coordinates the pulse load and the propulsion load to reduce the impact of pulse load changes on the power quality of all-electric ship power systems. The dynamic behavior of the new method is evaluated using case studies in PSCAD software.

Dynamic load management for NG IPS ships

A simplified notional Next Generation Integrated Shipboard Power System (NG IPS) model is introduced. Based on the simplified system model, dynamic load management method is presented considering equality and inequality constraints of the system. The problem is formulated as a dynamic optimization problem to maximize the energized loads in the system without violating any constraint of the system. A simplified NG IPS model is simulated in PSCAD, and three scenarios are presented to illustrate the dynamic load management method. The simulation results indicate that the dynamic performance of the shipboard power system model with load management is much better than its performance without load management.

A new adaptive inertia weight strategy in particle swarm optimization

According to the principle of mechanics, a new adaptive inertia weight strategy is proposed. The strategy depends on particles search states including its location and velocity instead of iteration times. Based on the proposed strategy, an inertia weight function is designed, which is continuous in real domain, thus its easy to be implemented and the computation cost is low. Experiments on three benchmark functions, comparison between convergence speed, the ability to search the global solution of the linear decreasing strategy (LPOS) and the proposed strategy are done. The experimental results are also analyzed in detail.

A class of cyber-physical switching attacks for power system disruption

In this paper, we present the development of a new class of intelligent cyber-physical attacks termed coordinated switching attacks whereby opponents aim to destabilize the power grid through controlled switching. Such switching is facilitated by cyber attack and corruption of communication channels and control signals of the associated switch(es). The attack employs a variable structure systems theory model of a smart grid. The sliding mode theory is employed to leverage emergent system properties to identify state-dependent switching sequences to disrupt power flow. Our results demonstrate the potential for coordinated switch attacks to enable large-scale power system disturbances.

Multi-agent system-based real-time load management for NG IPS ships in high/medium voltage level

Navy shipboard power systems have limited generation capacity and include a large portion of dynamic loads and high-energy weapon loads, which can overload the generators easily. The power generation and the load demand of the system should be balanced while satisfying the systems operating constraints in real-time to make the system operate normally. This paper presents a multi-agent system for the next generation integrated power system (NG IPS) in high/medium voltage level to coordinate a group of agents to cooperatively achieve the real-time load management objectives. The generator agent layer and load agent layer are designed to integrate a group of generators, propulsion loads, and DC zones into the multi-agent system. The cooperative control protocol is developed based on the proposed artificial potential function to achieve the group goals in real-time. The simulation results show that the developed technique achieves the real-time load management objectives.

Analysis of various partitioning strategies for multi-agent system-based real-time load management for NG IPs ships

The real-time load management techniques for next generation integrated power systems (NG IPS) for ships are being developed to balance the load demand and the power generation while satisfying the operating constraints of the system in real-time. To solve the real-time load management problem using a multi-agent system cooperative control protocol, the NG IPS must be partitioned into smaller subsystems that are modeled using dynamical agents. In this paper, three potential partitioning strategies are discussed along with their advantages and disadvantages. Unlike the first partitioning strategy modeling half a zone as an agent which aggregates a group of loads together, the last partitioning strategy models an agent for each electrical component and includes more system dynamics, which significantly increases the agent model accuracy. The results of the studies of the partitioning strategies can be utilized during the cooperative controller design to achieve real-time load management for NG IPS ships.