Chen-ching Liu - Independent Researcher (original) (raw)

Papers by Chen-ching Liu

Oceans '02 MTS/IEEE, 2002

The NEPTUNE power delivery system faces several challenges in serving the needs of the oceanograp... more The NEPTUNE power delivery system faces several challenges in serving the needs of the oceanographic community. Two major challenges, operating the system under normal conditions and protecting it against faults, require the development of new approaches unfamiliar to power engineers. In particular, the power management system must cope with several modes of potential system instability, and the protection system must operate in a deliberately weak system. Furthermore, it is likely that communications will be disrupted in the event of a fault. The approach taken to address these challenges is described.

ICT modeling for integrated simulation of cyber-physical power systems

2012 3rd IEEE PES Innovative Smart Grid Technologies Europe (ISGT Europe), 2012

ABSTRACT A cyber-physical system is a large and complex infrastructure. Due to the increasing con... more ABSTRACT A cyber-physical system is a large and complex infrastructure. Due to the increasing connectivity, the power and cyber systems become more interdependent. Models of the interactions are needed between the power devices and information and communication technology (ICT). A broad range of cyber attacks has become a serious concern. Cyber attacks must be simulated to analyze the consequences on the power grid. Thus, the cyber system must be modeled explicitly and integrated with the power grid model. This paper describes the development and simulation of a novel co-simulation framework that integrates both the cyber and power systems. The objective is to implement the ICT model for real-time interactions with both the power grid and transmission operator. Different industrial grade environments have been developed to simulate the cyber-power interactions. ICT events that may affect the stability of the grid, e.g., cyber attacks, are simulated at the cyber system layer, and their impact analysis is conducted at the power system layer. The proposed co-simulation framework is validated with the IEEE 39-bus system.

Using market simulation to manage price risk in a centrally cleared market

199 IEEE Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.99CH36364), 1999

Risk management is needed to quantify and mitigate the price risk associated with uncertain price... more Risk management is needed to quantify and mitigate the price risk associated with uncertain prices. Electricity prices in competitive markets display a very high short-term volatility. This volatility results in part from the fact that the electrical system has physical constraints such that failures of system devices cause sharp changes in the available supply. Managing price risk requires a statistical forecast for the expected range of prices for electricity. This forecast must involve simulation of the market to capture physical and financial effects. Value-at-risk is an established method for measuring the risk a company is exposed to for price changes. A fundamental component of risk management is forecasting market prices including variances. This presentation introduces established concepts of value-at-risk analysis for electricity markets and proposes a methodology for simulation of the underlying physical market

Coupling market clearing with congestion management to prevent strategic bidding

199 IEEE Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.99CH36364), 1999

The potential for strategic bidding in deregulated electricity markets is well known. Earlier wor... more The potential for strategic bidding in deregulated electricity markets is well known. Earlier work has highlighted the role of congestion in such strategies. The authors examine a model in which a supplier can create congestion problems in a noncongestive system even when he is the not the low cost supplier of the system. If that supplier has several units located at different buses in the grid, it can profit from creating congestion under some auction mechanisms actually in use or under consideration. An integrated auction prevents profitable gaming, but requires the simultaneous handling of market clearing and system dispatch, raising concerns about the neutrality of the system operator. This paper provides a practical demonstration of the integrated auction, and compares it to other mechanisms

Decision making of an electricity supplier's bid in a spot market

199 IEEE Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.99CH36364), 1999

In a market environment, profitability is the main objective for market players. This paper descr... more In a market environment, profitability is the main objective for market players. This paper describes an environment in which suppliers sell electricity via a single auction system, e.g., the UK market. The suppliers submit bids to sell electricity. The market is cleared by maximizing social welfare, subject to power system operational constraints. The bidding decision is optimized from a single

New methods for electric energy contract decision making

DRPT2000. International Conference on Electric Utility Deregulation and Restructuring and Power Technologies. Proceedings (Cat. No.00EX382), 2000

New Methods for Electric Energy Contract Decision Making ... Chen-Ching Liu* Haili Song Jacques L... more New Methods for Electric Energy Contract Decision Making ... Chen-Ching Liu* Haili Song Jacques LawarrCe Robert Dahlgren ... Department of Electrical Engineering Department of Economics ALSTOM ESCA Corp. University of Washington, Seattle WA 98195

A Petri net algorithm for scheduling of generic restoration actions

IEEE Transactions on Power Systems, 1997

This paper is concerned with scheduling of the restoration actions. Generic restoration actions (... more This paper is concerned with scheduling of the restoration actions. Generic restoration actions (GRAs) have been identified in the authors' previous research based on a variety of restoration strategies used by electric utilities. This paper proposed a scheduling method using the Petri net (PN) techniques. The PN model incorporates the conditions that have to be met before an action can

Cyber-power system security in a smart grid environment

2012 IEEE PES Innovative Smart Grid Technologies (ISGT), 2012

ABSTRACT Smart grid heavily relies on Information and Communications Technology (ICT) to manage t... more ABSTRACT Smart grid heavily relies on Information and Communications Technology (ICT) to manage the energy usage. The concept of smart grid implies the use of “smart” devices, such as smart meters or Remote Terminal Units (RTUs), that require extensive information to optimize the power grid. As the communication network is based on TCP/IP and Ethernet technology, new cyber vulnerabilities are introduced that can be exploited by malicious attackers. Cyber security has become a serious concern due to various intrusion incidents. Cyber attacks can make a significant impact on the grid, which will involve not only steady-state but also dynamic behaviors. A cyber-power system approach has been established that explicitly models the interaction between ICT and the power system. New technologies are under development to enhance the ICT vulnerability assessment and evaluate the impact of cyber attacks on system operation. This paper presents the cyber security issues in a smart grid environment and cyber attack/mitigation scenarios using a testbed at University College Dublin (UCD).

Placement of Remote-Controlled Switches to Enhance Distribution System Restoration Capability

IEEE Transactions on Power Systems, 2015

A Fast EMT Simulation Method for Control and Protection Studies of Microgrids

In this work, ac-dc hybrid microgrids are studied, which contains inverter-interfaced distributed... more In this work, ac-dc hybrid microgrids are studied, which contains inverter-interfaced distributed generators (DGs) and storages (DSs). As an effective way, electromagnetic transient (EMT) simulations are widely adopted for studies on control and protection strategies of these microgrids. However, detailed EMT simulations are time-consuming, especially for microgrids with many inverter-interfaced DGs/DSs. Based on model reduction, this paper proposes a fast EMT simulation method for microgrids. A piecewise averaged model (PAM) of inverter-interfaced DGs/DSs is established and integrated into the Electromagnetic Transient Program (EMTP). Using a microgrid with 2 PV generators and 1 battery energy storage system (BESS) as test system, the proposed method is verified by comparing simulation results with those obtained from a detailed model built in PSCAD/EMTDC. The results indicate that the proposed method can effectively speed up EMT simulation of microgrids with negligible lost in acc...

Piecewise Average-Value Model of PWM Converters with Applications to Large-Signal Transient Simulations

IEEE Transactions on Power Electronics

Proceedings of the 13th International Conference on, Intelligent Systems Application to Power Systems, 2005

For a market player, in order to perform an optimal risk management, it is important to have not ... more For a market player, in order to perform an optimal risk management, it is important to have not only suitable price forecasting tools taking into account the most significant price drivers but also methods to quantify their accuracy. This paper proposes an intelligent system for price forecasting accuracy assessment (ISPF). The core of ISPF is a fuzzy interpolator of the effects of the price drivers; the output is a set of pre-defined price indices over a medium term period. The computational efficiency of ISPF allows its repeated application in a Monte Carlo methodology, in order to calculate the price indices corresponding to a very large number of price drivers values combinations and, then, to determine the probability distributions of the corresponding price indices. The paper reports an application of the proposed ISPF to the forecasted Italian market scenario for year 2005.

Decision support for restoration of interconnected power systems using tie lines

IET Generation, Transmission & Distribution, 2015

2012 IEEE Power and Energy Society General Meeting, 2012

New technologies including microprocessor-based Intelligent Electronic Devices (IEDs) and standar... more New technologies including microprocessor-based Intelligent Electronic Devices (IEDs) and standardized protocol and TCP/IP over wide area networks (WAN) are well-adopted in the substations. Remote access to IEDs or user interfaces in a substation for maintenance purposes is a common practice. However, there are potential cyber-physical system vulnerabilities in a substation, e.g., unsecured standard protocols, remote controllable IEDs, and unauthorized remote access to substation IEDs. In addition, some substation IEDs and user interfaces have a web server and hence it may provide a remote configuration change and control with default passwords. Even if firewalls and cryptography schemes are used for cyber security, weak security key management cryptography and mis-configured firewalls are still exposed to intruders. From IT point of view, cyber security issues are well known and new security technologies are available. However, security research on the integration of IT and physical power systems for critical infrastructures is still an emerging area.

Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2013

Digital forensic investigators commonly use dynamic malware analysis methods to analyze a suspect... more Digital forensic investigators commonly use dynamic malware analysis methods to analyze a suspect executable found during a post-mortem analysis of the victim's computer. Unfortunately, currently proposed dynamic malware analysis methods and sandbox solutions have a number of limitations that may lead the investigators to ambiguous conclusions. In this research, the limitations of the use of current dynamic malware analysis methods in digital forensic investigations are highlighted. In addition, a method to profile dynamic kernel memory to complement currently proposed dynamic profiling techniques is proposed. The proposed method will allow investigators to automate the identification of malicious kernel objects during a post-mortem analysis of the victim's acquired memory. The method is implemented in a prototype malware analysis environment to automate the process of profiling malicious kernel objects and assist malware forensic investigation. Finally, a case study is given to demonstrate the efficacy of the proposed approach.

Characterization of power system small disturbance stability with models incorporating voltage variation

ABSTRACT

On-line fault diagnosis using sequence-of-events recorder information

Proceedings of International Conference on Intelligent System Application to Power Systems, 1996

This paper presents a new logic-based method for online power system fault diagnosis in a control... more This paper presents a new logic-based method for online power system fault diagnosis in a control center environment. The unique feature of the approach is the use of sequence of events recorder information from substations, together with data acquired by the energy management system (EMS). A proposed line fault proof algorithm is applied to a line if any protective device

Analysis and control of major blackout events

2009 IEEE/PES Power Systems Conference and Exposition, 2009

ABSTRACT This is a summary for presentation in the panel session, ldquoUnderstanding, Prediction,... more ABSTRACT This is a summary for presentation in the panel session, ldquoUnderstanding, Prediction, Mitigation and Restoration of Cascading Failuresrdquo at IEEE PES PSCE 2009. Recent major blackouts in North America, Europe, and other countries highlight the importance of reliability of our electric energy infrastructure and the economic impact of blackouts. These blackouts were caused by a cascading sequence of events including line tripping, overloading of other lines, malfunctions of protection devices, power oscillations and voltage instability, and system splitting and collapse. In this presentation, common characteristics of blackouts are clarified by analyzing the cascaded events of the major blackouts. Appropriate control actions to alleviate emergency conditions including overloads are vital to prevent cascaded events. On the basis of the common characteristics of blackouts, the panelist will discuss available control actions for overloads through system operation and emergency control. The future research needs for mitigating cascaded events will be discussed.

State-of-the-art of electricity price forecasting

International Symposium CIGRE/IEEE PES, 2005., 2005

Abstract--1Since the deregulation of the electricity power industry, many methods and techniques ... more Abstract--1Since the deregulation of the electricity power industry, many methods and techniques have been developed to forecast the electricity prices in the competitive environment. This paper classifies and compares different techniques in the literature of electricity price ...