Detection of Symmetrical Faults by Distance Relays During Power Swings

For maintaining security of distance relays, power swing blocking is necessary to prevent unintended operation under power swings. To be dependable, distance relays must operate whenever a fault occurs. Therefore, detecting faults during power swings is an important issue since the relay should be able to differentiate the fault condition and not be blocked during that time. This paper presents a new method for detecting a symmetrical fault during a power swing, based on extracting components of the current waveform using the Prony method. The merit of the method is demonstrated by simulating different faults during power swing conditions using the Alternate Transients Program version of the Electromagnetic Transients Program.     

Design optimization and performance evaluation of the relayingalgorithms, relays and protective systems using advanced testing tools

This paper defines underlying performance quality measures for designing, optimizing, setting and evaluating the protective relaying algorithms and equipment. The paper starts with evaluation of digital measuring algorithms, and gradually introduces the performance indices for the operating principles, relays and protection systems. Multi-objective formal ranking methods based on fuzzy set theory are used to combine diverse measures into composite performance indices enabling evaluating and optimizing various functions of protective equipment     

Automated monitoring and analysis of circuit breaker operation

This paper describes a solution for automated analysis of circuit breaker operation. The analysis is based on a record of waveforms taken from the circuit breaker control circuit by using a portable recorder and manually forcing an operation of the breaker. This solution was driven by a need to perform the analysis in a more timely and consistent manner than what is available with existing technology. The solution is implemented using advanced wavelet transforms for waveform feature extraction and an expert system for decision making. A web-based database solution for storing and retrieving both the field-recorded and processed data is also implemented. The software is developed in two versions: for field (substation) as well as off-line (office) applications.     

A new method for the CCVT performance analysis using fieldmeasurements, signal processing and EMTP modeling

This paper presents the results of an EPRI study on development of a new method for coupling capacitor voltage transformer (CCVT) frequency response measurements from the secondary side. The method is especially suitable for field measurements since it does not require any internal CCVT disassembly or access to its individual components. It has been verified by performing the field measurements on actual CCVTs installed in a substation. The results were compared with the results obtained by carrying out the CCVT frequency response measurements on the same type of CCVTs in a laboratory and using the method of frequency response measurement from the primary side. The proposed method is easy to use and gives accurate results. The method may be used for the EMTP-based CCVT model development and the CCVT performance analysis     

A new analysis method for early detection and prevention of cascading events

This paper introduces a new analysis method for early detection and prevention of power system cascading events. It uses the vulnerability index (VI) and margin index (MI) to evaluate the vulnerability and security of the individual system parts, as well as the whole system during an operating state. It identifies the vulnerable parts of the power system using the topology processing and operation index methods. For a given disturbance, it calculates the power flow, evaluates the vulnerability and security, identifies the vulnerable part, finds the transmission line overload and bus voltage problems, and predicts the possible successive events. The approach defines the control means using the following methods for early detection and prevention of cascading events: network contribution factor (NCF), generator distribution factor (GDF), load distribution factor (LDF), and selected minimum load shedding (SMLS). This approach has been tested using the IEEE RTS-96 24-bus system and promising results have been obtained. The proposed approach allows the power system operator to detect initial stages of cascading events and assert actions that will prevent such events from unfolding.     

Impact of wind generation uncertainty on power system small disturbance voltage stability: A PCM-based approach

The connection of wind generators with electric power system influences the system stability and nodal voltages. This paper performs uncertainty analysis to investigate the impact of wind generation variation on the small disturbance voltage stability. The probabilistic collocation method (PCM) is presented as a computationally efficient method to conduct the uncertainty analysis. It has been implemented in a simple system to demonstrate its applicability in analyzing wind generation uncertainty. More case studies on a larger system are conducted to obtain a deeper understanding of how the system voltage stability is affected by the integration of DFIG-based wind farms. As compared with the traditional Monte Carlo simulation method, the collocation method could provide a quite accurate approximation for the eigenvalue probabilistic distribution with fewer simulation runs.     

Data integration/exchange - Part 1: existing technical and business opportunities

The deregulation of the electric utility industry combined with development of advanced technology has raised many questions as how to make the power system operation more cost effective while preserving a high level of reliability and security. The utilities are developing different strategies for achieving this goal, enabling them to stay competitive. Many other new businesses are being formed to take advantage of the new opportunities in the marketplace.This article provides an overview of the possible new technical and business opportunities and benefits in developing advanced strategies for data integration and information exchange. It describes the efforts to discover new approaches to formulating a successful business strategy that would ensure competitiveness, with particular focus on the role of data integration and information exchange in developing new technical and business opportunities in the deregulated market place. In order to put the above discussion into better perspective, two new applications, namely a comprehensive fault and disturbance analysis and a novel two-stage state estimation, are presented as illustrative examples of how additional benefits can be obtained through assigning new business value to information and data.     

Is teamwork the smart solution?

One of the most formidable tasks facing humanity at the moment is how to solve the problems associated with energy supply and utilization. The issues are complex, to be sure, and they're compounded by seemingly conflicting objectives involving cost, sustainability, reliability, environmental soundness, free markets, and an energy supply that is accessible to all--anytime. Because there?s special interest in enhancing the sustainability of a modern lifestyle, one approach to the problem is to use renewable resources--mainly solar and wind--to power the world economy. Some renewable resources have the added benefit of low environmental impact, especially in greenhouse gas production. There's also great interest in restructured energy and power markets that are called "free" or "liberalized" in some parts of the world and "deregulated" in the United States. The deregulation of the electric power industry in many venues has resulted in a new science and engineering of power marketing. There are complex basic challenges in solving the problems that are related to an unfettered power market that results in an environmentally sound production of electric power and also a reliable and low-cost solution.