James D. McCalley

Damping controller design for power system oscillations using global signals

This paper describes a new power system stabilizer (PSS) design for damping power system oscillations focusing on interarea modes. The input to the PSS consists of two signals. The first signal is mainly to damp the local mode in the area where PSS is located using the generator rotor speed as an input signal. The second is an additional global signal for damping interarea modes. Two global signals are suggested; the tie-line active power and speed difference signals. The choice of PSS location, input signals and tuning is based on modal analysis and frequency response information. These two signals can also be used to enhance damping of interarea modes using SVC located in the middle of the transmission circuit connecting the two oscillating groups. The effectiveness and robustness of the new design are tested on a 19-generator system having characteristics and structure similar to the Western North American grid.

Design Techniques and Applications of Cyberphysical Systems: A Survey

Cyberphysical systems (CPSs) are new class of engineered systems that offer close interaction between cyber and physical components. The field of CPS has been identified as a key area of research, and CPSs are expected to play a major role in the design and development of future systems. In this paper, we survey recent advancements made in the development and applications of CPSs. We classify the existing research work based on their characteristics and identify the future challenges. We also discuss the examples of prototypes of CPSs. The aim of this survey is to enable researchers and system designers to get insights into the working and applications of CPSs and motivate them to propose novel solutions for making wide-scale adoption of CPS a tangible reality.

Identifying high risk N-k contingencies for online security assessment

It is impractical to analyze all of the possible contingencies in a large-scale interconnected power network. Therefore, a standard approach is to analyze only a subset of the contingencies. The normal method of selecting this subset is via use of the so-called N-1 rule. This paper goes a step further by proposing a new method of forming a contingency list, based on substation configuration obtained from topology processing data and probability analysis of protection system failures. This method is particularly suited for online security assessment. Protection system failures assessed include stuck breakers and failure to operate. The method is described via application to a single substation, verified using the IEEE-RTS96, and illustrated using topology data from a large utilities EMS.

An overview of risk based security assessment

We describe weaknesses in using deterministic methods for performing security assessment for bulk transmission systems. We also present motivation for using probabilistic risk and provide fundamental relations for making the associated calculations. The benefits and applications of using a risk index for security assessment are discussed, and an illustration is provided for line overload security assessment in the operational context.

Reliability issues in today's electric power utility environment

Considerable change is occurring in the structure and operation of electric power systems throughout the world. This paper describes some of these changes in North America and Europe, the forces creating them and the possible reliability issues associated with them. The main changes are deregulation and privatisation in the electric utility environment.

Application of NSGA-II Algorithm to Generation Expansion Planning

This paper describes use of a multiobjective optimization method, elitist nondominated sorting genetic algorithm version II (NSGA-II), to the generation expansion planning (GEP) problem. The proposed model provides for decision maker choice from among the different trade-off solutions. Two different problem formulations are considered. In one formulation, the first objective is to minimize cost; the second objective is to minimize sum of normalized constraint violations. In the other formulation, the first objective is to minimize investment cost; the second objective is to minimize outage cost (or maximize reliability). Virtual mapping procedure is introduced to improve the performance of NSGA-II. The GEP problem considered is a test system for a six-year planning horizon having five types of candidate units. The results are compared and validated.

A Multiperiod Generalized Network Flow Model of the U.S. Integrated Energy System: Part I—Model Description

This paper is the first of a two-part paper presenting a multiperiod generalized network flow model of the integrated energy system in the United States. Part I describes the modeling approach used to evaluate the economic efficiencies of the system-wide energy flows, from the coal and natural gas suppliers to the electric load centers. Under the proposed problem formulation, fuel supply and electricity demand nodes are connected via a transportation network, and the model is solved for the most efficient allocation of quantities and corresponding prices. The methodology includes physical, economic, and environmental aspects that characterize the different networks. Part II of this paper provides numerical results that demonstrate the application of the model

A risk-based security index for determining operating limits in stability-limited electric power systems

This paper is motivated by a concern that dynamic security limits based on the most severe contingency and scenario often result in operating restrictions corresponding to low or no risk but very high costs. A new risk-based security index is presented which accounts for both probability and impact of instability and is useful in determining operating limits. The approach is illustrated for a stability-limited system in Arizona.

Probabilistic security assessment for power system operations

Control room operators are faced with frequent security-economy decision-making situations necessitated by stressed system operating conditions, and there is increased need for security-economy decision-support tools. Although probabilistic methods are promising in this regard, they have been mainly used in planning environments. This task force paper explores their use for operational decision-making, comparing them to the more traditional deterministic approach. Two examples are used to facilitate this comparison via overload and low voltage security assessment to identify secure regions of operation for a small 5-bus system and for the IEEE Reliability Test System. The results of this comparison show that the probabilistic approach offers several inherent advantages.

Power System Risk Assessment and Control in a Multiobjective Framework

Traditional online security assessment determines whether the system is secure or not, but how secure or insecure is not explicitly indicated. This paper develops probabilistic indices, risk, to assess real-time power system security level. Risk captures not only event likelihood, but also consequence. System security level associated with low voltage and overload can be optimally controlled, using the NSGA multiobjective optimization method. A security diagram is used to visualize operating conditions in a way that enables both risk-based and traditional deterministic views. An index for cascading overloads is used to evaluate the Pareto optimal solutions. This paper shows that the multiobjective approach results in less risky and less costly operating conditions, and it provides a practical algorithm for implementation. The IEEE 24-bus RTS-1996 system is analyzed to show that risk-based system security control results in lower risk, lower cost, and less exposure to cascading outages.