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.

Cascading Failure Analysis of Cyber Physical Power System With Multiple Interdependency and Control Threshold

Abstract: The traditional infrastructure in power system is undergoing a transition to the Smart Grid, in which the communication network and power grid will be integrated into a cyber-physical power system (CPPS). Although the traditional topological analysis reveals the mechanism of cascading failure between two networks, it ignores the control redundancy and standby lines from communication network to power grid. The robustness analysis in CPPS requires a more comprehensive model to analyze failure behavior in reality. Here, we propose a cascading failure model with one-to-multiple interdependency and a relevant theoretical framework to analyze CPPS cascading failure. In consideration of real CPPS, in the proposed model we introduce two robustness factors, the number of dependent links and control threshold, which can better describe the control function from communication nodes to power nodes. The remaining fraction under different initial attacking on high voltage transmission network, small world network, double star network, and the different topological combination of CPPS are analyzed. The results show that the proposed model and robustness factors can better reveal the robustness and the mechanism of two networks in cascading failure.

Improving Real-time Fault Analysis and Validating Relay Operations to Prevent or Mitigate Cascading Blackouts

Abstract: This paper proposes a new strategy at the local (substation) level, aimed at preventing or mitigating the cascading blackouts that involve relay misoperations or inadequate local diagnostic support. The strategy consists of an advanced real-time tool that combines neural network based fault detection and classification (NNFDC) algorithm and synchronized sampling based fault location (SSFL) algorithm with a relay monitoring tool using event tree analysis (ETA). The fault analysis tool provides a reference for conventional distance relay with its better performance and the relay monitoring tool provides detailed local information about the disturbances. The idea of the entire strategy is to meet several NERC recommendations to prevent blackouts using wide area protection and control

Real Time Parameter Estimation for Power Quality Control and Intelligent Protection of Grid-Connected Power Electronic Converters

Abstract: This paper presents a method to identify power system impedance in real-time using signals obtained from grid- connected power electronic converters. The proposed impedance estimation has potential applications in renewable/distributed energy systems, STATCOM, and solid state substations. The method uses wavelets to analyze transients associated with small disturbances imposed by power converters and determine the net impedance back to the source. A data capture period of 5 ms is applied to an accurate impedance estimation which provides the possibility of ultra fast fault detection (i.e., within a half cycle). The paper describes how the proposed method would enhance the distributed generation operation during faults.

Unprotected faults of electrical cords and extension cords in AC and DC systems

Abstract: In electrical power systems, all the wiring exposed to mechanical damages and other insulation stresses, such as flexible cords, can be involved in overheating, arcing, and burning Mechanical damages of the stranded bare conductors can locally degrade the effective sizing of the cross section and cause anomalous local conditions The circuit protective devices (PDs) can be unfit to detect the faults of cords that remain so energized and available to electric shock and fire hazards Some fire ignitions result from these types of special unprotected faults To highlight the local incident energy in case of fault, this paper introduces the parameters steady and transient current densities that assist in analyzing these fault events Efficient protection can be achieved by the integration of active and passive techniques: adopting arc-fault circuit interrupters or detection devices, recognizing arcing faults, and wiring circuits with a grounding protection conductor to involve the ground in every fault that, in ac systems, is rapidly protected by residual current PDs (or ground-fault PDs) At this aim, the use of special cables, namely, ground-fault-forced cables, is recommended, particularly for cords and extension cords also supplying Class II equipment The dc system protection requires special care

Transmission Network Protection: Theory and Practice

Abstract: From the basic fundamentals and principles of protective relaying to current research areas in protective systems and future developments in the field, this work covers all aspects of power system protection. It includes the implementation of relays using electromechanical devices, static devices and microprocessors; distance protection of high voltage and extra high voltage lines, including distance relay errors; and adaptive, dynamic, travelling wave and noise-based relays.