Power-system protection

About: Power-system protection is a research topic. Over the lifetime, 6353 publications have been published within this topic receiving 117961 citations.

Software Agents Situated in Primary Distribution Networks: A Cooperative System for Fault and Power Restoration Management

Abstract: In this paper, extended research upon the potentials of implementing distributed artificial intelligence technology to achieve high degrees of independency in distribution network protection and restoration processes is presented. The work that has already been done in the area of agent-based and/or knowledge-based applications and expert systems is briefly reviewed. The authors justify the need to distribute activities in contradiction to the centralized methodologies. A proper model of the real environment is introduced in order to define the designing parameters of a prototype agent entity, which is the part of a cooperative network-management system. The system's goal is to autonomously perform effective fault management upon medium-voltage power distribution lines. The structure of the agent entity is then described by means of the agent behaviors being implemented. The cooperative operations of the proposed system and its computer simulation are presented. Simulation results are being evaluated. Finally, general conclusive remarks are made.

An Integrated Control and Protection Scheme to Inhibit Blackouts Caused by Cascading Fault in Large-Scale Hybrid AC/DC Power Grids

Abstract: Cascading fault is one of the serious challenges in hybrid ac/dc power grids, which initiates from a dc or a severe inverter ac fault and leads to a blackout in the inverter ac side. However, owing to the fact that dc faults do not cause commutation failure, the existing commutation failure inhibition approaches are not effective in the prevention of cascading faults caused by dc fault. In order to resolve the challenge, this paper first develops a hybrid ac/dc relay (HADR) based on the positive-sequence component, which can detect and locate the fault events in hybrid ac/dc networks. Subsequently, an integrated control and protection scheme is presented using the developed HADR and a thyristor-controlled series compensator. The proposed scheme has the ability to prevent the blackouts caused by cascading fault using transmission capacity enhancement of the ac line and load-shedding in the inverter ac system. The salient feature of the proposed scheme is that it provides a very economical way to compensate for the loss of power caused by HVdc line outage. In addition, it does not require communications among the relays. The practical performance and feasibility of the proposed scheme is validated by laboratory testing, using the real-time Opal-RT hardware prototyping platform. The experimental results demonstrate that the proposed strategy can effectively inhibit the blackouts caused by cascading fault in hybrid ac/dc networks.

Frequency and transient behavior of grounding systems. II. Practical application examples

Abstract: In this paper, the authors present the application of the methodology and computational procedures described in part I of this paper to basic practical problems of electromagnetic compatibility, including: the effects of lightning discharges in electrical grounding systems and the definition of risks for human safety; for equipment damage and of noncorrect operation of control and protection schemes; procedures to limit the consequences of lightning; interference, through ground systems, in sensitive circuits, considering frequency dependence of interaction of power equipment with sensitive elements and surge type phenomena; and procedures to limit interference.

Automated Graph-Based Methodology for Fault Detection and Location in Power Systems

Abstract: This study investigates how the model-based fault detection and location approach of structural analysis can be adapted to meet the needs of power systems, where challenges associated with increased system complexity make conventional protection schemes impractical. With a global view of the protected system and the systematic and automated use of the system's analytical redundancy, faults are detected and located by more than one means. This redundancy can be used as a confirmation mechanism within a wide-area protection scheme to avoid unnecessary or false tripping due to protection component failure or disturbance. Furthermore, this redundancy turns the sensor configuration problem into an optimization problem with regard to fault detection and location. The effectiveness of different system topologies can then be compared on the basis of the optimal number of sensors they require. The principle of structural analysis is described in detail and illustrated on a simple power system model. Pertinence of the approach is demonstrated through simulation.

Development and Investigation of a New High-Speed Directional Relay Using Field Data

Abstract: In this paper, a new high-speed directional relay is proposed. The relay is based on the current and voltage signals before and after fault occurrence. The voltage signal is compensated and then used as a reference. The relay is used for the directional comparison protection of extremely high voltage transmission lines. An evaluation of the suggested directional relay is investigated using recorded fault data from the Alberta power transmission system. The real effects of the power system elements, which might have not been completely considered in the mathematical model of the power system, have been included in the recorded real fault data. In this case, the performance of the new directional relay can be verified in a more realistic environment than simulation.