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.

A differential zone protection scheme for microgrids

Abstract: Microgrids are small networks of loads and sources that can operate either connected to the grid or islanded. In order to operate in islanded mode, the microgrid must have a new protection scheme as classical distribution protection is inadequate. This work develops a differential zone protection scheme that works by comparing current measurements from several devices on the boarders of the zones. This method is as effective at detecting microgrid faults as digital relay differential protection schemes at significantly lower costs. The optimal placement of zones and devices is formulated. A case study shows that the optimal placement solution can reduce costs by more than 50% when compared to having a relay at each line segment.

Negative-sequence differential protection - principles, sensitivity, and security

Abstract: This paper explains the principles of negative-sequence differential (87Q) protection, its basis for excellent sensitivity and speed, and the need for securing it with external fault detectors to deal with the saturation of current transformers The paper reviews applications of 87Q elements to lines and transformers It explains why 87Q elements cannot be used for turn-to-turn fault protection in shunt reactors and stators of generators and motors The paper presents applications of negative-sequence directional elements for turn-to-turn fault protection in reactors and stators Finally, it derives two new protection principles based on negative sequence for generator turn-to-turn fault protection

System-wide Protection

Abstract: By its very definition, as applied to power system protection, wide-area measurement systems (WAMSs) are a synergistic combination of relays, measuring instruments, control equipment, automation equipment, monitoring equipment, and communication employed to encompass extensive system elements as opposed to the more traditional view of individual equipment or point-to-point protection. The increasing world-wide application of digital devices and high-speed wideband communication and global positioning systems (GPSs) plus the growing acceptance of adaptive relay protection philosophy and practice have dramatically altered the fundamental role of power-system protection.

Detecting and Locating Faulty Nodes in Smart Grids Based on High Frequency Signal Injection

Abstract: An on-line method for detecting and locating a faulty node in the utility grid is proposed for smart grids. The method is based on injection of high frequency (A-Band) current signal into the grid that would impose voltages (less than 1V according to EN50065-1 standard) on the nodes to determine changes in the impedance characteristics. This detection is accomplished on-line without interrupting the power flow in the network. The developed algorithm has been implemented within an electrical power system model. This low voltage network model has been tested with different fault scenarios. The proposed procedure is able to detect the faulty nodes with high accuracy.

Protection strategy for undersea MTDC grids

Abstract: Many point to point HVDC lines are already in operation in several countries. However, the development of multi-terminal DC grids is slowed by the lack of efficient control and protection strategies that can be applied on such grids. This article deals with the protection aspect of those networks. Indeed, the resort to Voltage Source Converters (VSC) changes the constraints since the short circuit current can flow through the freewheel diodes in case of the event of a DC fault. Also, since several links are considered, selectivity rules need to be investigated in order to maintain the healthy part of the grid in operation. A protection plan is proposed and its robustness and limitations are investigated.