Khalil El-Arroudi

Intelligent-Based Approach to Islanding Detection in Distributed Generation

This paper introduces a new intelligent-based approach for detecting islanding in distributed generation (DG). This approach utilizes and combines various system parameter indices in order to secure the detection of islanding for any possible network topology, penetration level and operating condition of the DG under study. Hence, every parameter index displays characteristics for a given set of events. The proposed technique uses the data-mining technology to extract information from the large data sets of these indices after they are screened off-line via massive event analyses using network simulations. The technique is tested on a typical DG with multiple distributed resources and the results indicate that this technique can successfully detect islanding operations. In addition, this technique can also overcome the problem of setting the detection thresholds inherent in the existing techniques by optimizing their settings

Operation of Impedance Protection Relays with the STATCOm

This paper presents analytical and simulation results for investigating the operation of impedance-based protection relays in a power system containing a flexible alternating current transmission (FACTS) controller such as static synchronous compensator (STATCOM). The analyses are based on steady state operation for modeling the STATCOM and the protection relays. The impact of the FACTS device on protection relays is studied for normal operating conditions as well as for fault conditions under different loading levels. Results for a case study are given.

A Fuzzy Rule-Based Approach for Islanding Detection in Distributed Generation

The proposed method develops a fuzzy rule-based classifier that was tested using features for islanding detection in distributed generation. In the developed technique, the initial classification boundaries are found out by using the decision tree (DT). From the DT classification boundaries, the fuzzy membership functions (MFs) are developed and the corresponding rule base is formulated for islanding detection. But some of the fuzzy MFs are merged based upon similarity the measure for reducing the fuzzy MFs and simplifying the fuzzy rule base to make it more transparent. The developed fuzzy rule-based classifier is tested using features with noise up to a signal-to-noise ratio of 20 dB and provides classification results without misdetection, which shows the robustness of the proposed approach for islanding detection for distributed generations in the distribution network.

Data Mining Approach to Threshold Settings of Islanding Relays in Distributed Generation

This paper introduces a new approach for determination of the threshold settings of islanding relays in distributed generation (DG) interconnections. This approach uses data-mining technology to extract the optimal relay settings information from a large data set of system parameters. This data is constructed from offline simulation analyses of events and consequences. The mining of these consequences defines the boundary limits of the threshold settings that could secure the detection of islanding operations under: minimum detectable zones, multiple distributed resources (DRs), diverse distributed resource technologies, various operating conditions, and different network topologies. The approach is tested on a typical DG with multiple distributed resources, and the results indicate that this approach can be used effectively to support the setting relay decision.

The Process of System Collapse Based on Areas of Vulnerability

The purpose of this paper is to introduce a new approach to the process of system collapse based on areas of vulnerability. For this purpose, a new category of contingencies called abnormal contingencies and a new system operating state called verge-of-collapse are proposed. The application of these abnormal contingencies to the vulnerable areas can lead to a system on the verge-of-collapse. In particular, there are two conditions that generally occur for a system to be on the verge-of-collapse: firstly, the system is in a degraded state or close to its operation limits and secondly it must be subjected to abnormal contingencies in the areas of vulnerability. The result of this study is to define areas of vulnerability in a network which can then be identified and appropriate remedial action initiated when required. Different stages are required for the protection of systems on the verge of collapse, namely: a) how to define areas of vulnerability, b) how to identify these areas of vulnerability and c) how to protect the system in the presence of areas of vulnerability. This paper is the first stage in proposing a new approach to the protection of systems on the verge of collapse

Comprehensive transmission distance protection settings using an intelligent-based analysis of events and consequences

This paper introduces a new methodology for settings of transmission system distance protection based on an intelligent analysis of events and their consequences. The output of the proposed methodology is comprehensive distance relay settings which include not only the zone reaches and zone time delays, as in the existing approaches, but also the optimal impedance operating characteristics, the fault detection settings, and the required relay sensitivities in terms of voltage and current. The need for this methodology is the result of the increased complexity of interconnected power systems protected with a large number of relays with different relay technologies, such as electromechanical, static, and numerical as well as diversity in their operating algorithms. The relay settings are automatically updated after every major change in the state of the network topology. Since it is not possible to include all design details of the proposed system, sample design events and rules are given to illustrate the proposed methodology.

Severity Index for Estimating the Impact of Wind Generation on System Vulnerability

This paper proposes a severity index for estimating the impact of penetration of wind energy on the vulnerability of a power system. This index is the risk of not meeting the load and is in fact the risk of failure of the probability distributions of the system load and the system generation including the wind penetration. This probabilistic approach is appropriate for a system with large wind generation installation due to the random nature of the wind generation output. The severity index is proposed to recognize the possible existence of an area of vulnerability at the point of common coupling (PCC). This approach does not preclude applying this methodology to a specific PCC bus in order to verify the impact on the security at each PCC bus in the planning stage and to alert the system operator of any possible shortfall of generation. A case study is provided to demonstrate the proposed approach.

The performance specification of transmission line protection using a knowledge-based approach

This paper introduces an automated approach to transmission line protection design for implementation in the form of a performance specification. The need for automation is the result of the increased complexity of interconnected power systems and despite numerous proprietary computer programs, the analysis of power system behavior requires significant engineering time and effort. Many scenarios have to be investigated before selecting and setting a protective relay and its equipment. By automating the running of the various computer programs and analyzing the results in a specific manner, the design scenarios can be investigated relatively quickly, cover all possible cases, remove protection design redundancy, preserve protection design methods, and assure consistency in protection system design. Additionally, by changing the system loading to some future anticipated value, it can be determined if specified relays and their equipment can be adjusted or will have to be replaced. It is also clear that such a design tool is useful in training system protection design engineers.

Performance of Interconnection Protection Based on Distance Relaying for Wind Power Distributed Generation

This paper proposes a method to analyze and improve the performance of interconnection protection based on distance relaying for wind power distributed generation (DG) in distribution systems. Of particular importance is distance protection that uses the concept of prefault voltages as reference quantities found to have issues with intermittent behavior of wind power DG. This concept is normally used in different distance protective relaying applications in order to increase the fault resistance coverage capability of the distance relays as well as to ensure selectivity, dependability, and security under extreme undervoltages. The main contributions of this paper are to analyze this issue and propose a method to enhance the performance of distance protection to mitigate this issue. In this methodology, several case studies are investigated with different penetration levels, weather patterns, and configuration topology of DGs under both normal operating conditions as well as fault conditions. Results for a case study are given.

Areas of Vulnerability in an Environment of Uncertainty

This paper addresses the vulnerability of power system operating in an environment of increasing uncertainty. Uncertainty can be related to the performance of a system under stress and the measures whereby this condition of possible system collapse could be identified and averted through remedial actions. For this reason, the paper begins with a definition of a vulnerable system as one that is in a degraded state and is then subjected to moderate disturbances that can lead to system collapse. When uncertain generation such as wind generation or deregulation is then introduced, these moderate disturbances can be regarded as variations in the wind generation or the system topology.