Certain power system situations force protection schemes to mal-operate. Such mal-operations associated with backup protection (BP) schemes might worsen the situation by initiating the cascading effect, damaging critical elements such as generation units, transformers etc. of the power system, or leading to complete collapse of the power system. To adapt to such a network structure, the relays which are going to participate in BP of transmission line have to evolve. Integration of protection systems, communication network, and computer technology has to be the approach for faster information sharing and decision making. Analysis of recent blackouts clearly shows the importance of advancement of wide-area measurement systems and adaptive nature of relaying. Synchro-phasors assisted BP scheme is proposed in this work, which helps the relays adapt according to the prevailing system situations and decisive action is taken considering security and dependability aspects of the relays. © The Institution of Engineering and Technology 2018.

Manas Kumar Jena

Department of Electrical Engineering

V. Nougain

B.K. Panigrahi

Fulltext

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

IET Generation, Transmission and Distribution

This paper presents a decentralized-approach-based wide-area back-up protection scheme to identify the faulted line in a power transmission network. The proposed scheme divides the whole power system under study into different protection zones (PZs) corresponding to generator bus(es). Furthermore, a 'gain in momentum' (GIM) index at each generator bus is used to minimize the search set. This information helps in reducing the search space to the PZ corresponding to the generator bus with highest GIM following a fault. This area is termed as a vulnerable protection zone (VPZ). Once the VPZ is identified, positive-sequence voltage magnitudes of each bus within the VPZ are monitored to locate the bus closest to the fault (BCF). Finally, reactive power-flow information of each line connected to the BCF is used to identify the faulted line. The performance of the proposed scheme is extensively validated on the Western System Coordinating Council-9 bus system, the IEEE-39 bus New England system, and 246-bus North India Grid using the Power System Simulation for Engineering. The test results indicate that the proposed scheme is highly effective for the WABP of transmission lines. © 2007-2012 IEEE.

IEEE Systems Journal

A New Decentralized Approach to Wide-Area Back-Up Protection of Transmission Lines

This paper presents a new methodology to adaptively shift the dependability and security bias of the transmission system protection logic depending on the system state. Contingencies such as generator outage, line outage, and line fault can induce stressed system condition. Under stressed conditions, protection logic should be more biased toward security. Phasor measurement unit information is used at the system protection centre to estimate the system state. A data-mining model known as random forest is utilized to accomplish the task of state assessment. Two different protection logics are used to make the final relaying decision. The first protection logic is the existing distance relay and the second protection logic is based on wide area information. Both the protection logics are connected though logic gates to make the final relaying decision. The performance of the proposed scheme is validated on the IEEE-39 bus New England system and 246-bus Indian Northern Regional Power Grid system. The test results indicate that the proposed algorithm can help in shifting the dependability-security bias of the protection logic adaptively, which will help in mitigating cascaded outages in the power transmission system. © 2010-2012 IEEE.

IEEE Transactions on Smart Grid

A new adaptive dependability-security approach to enhance wide area back-up protection of transmission system

This paper presents a new wide-area backup protection scheme based on the phase angle of positive-sequence integrated impedance (PAPSII). The proposed scheme uses phasor measurement units (PMUs) that comply with standard C37.118.1-2011 for retrieving the phasor information. The PMUs provide the positive-sequence phasor information of the voltage and current signals at each and every bus of a system to a phasor data concentrator (PDC). The positive-sequence integrated impedance of each line of the system is extracted, and the PAPSII of each line is continuously monitored at the PDC. The values of the PAPSII help in identifying the faulted line of the power transmission system. The proposed scheme is extensively tested for different types of fault scenarios on a three-machine nine-bus power transmission network on a real-time digital simulator platform. Critical issues such as voltage inversion, current inversion, load encroachment, and the power swing are addressed in the proposed scheme. The test results indicate that the proposed scheme can overcome the limitations of existing backup protection schemes and can provide a reliable protection measure. © 2007-2012 IEEE.

Journal	IET Generation, Transmission and Distribution
Publisher	Institution of Engineering and Technology
ISSN	17518687
Open Access	No