Line protection: Redundancy, reliability, and affordability

The reliability of a power system network depends greatly on the performance of the protection system. Improving the reliability of the protection scheme of the transmission lines will enhance the overall reliability of the power system network. The focus of this paper is the improvement of the reliability of a power system transmission line using fault tree analysis (FTA). The paper considers the development of fault tree diagrams for the protection scheme of the 150km-long 132-kV transmission line in Northern Nigeria. The existing protection scheme is analyzed and compared with a proposed scheme equipped with a redundancy arrangement. And the result shows that the new scheme offers significant improvement (about 51%) in the availability of the line.

2016

Special protection schemes (SPS), known also as remedial action schemes, are those designed to detect one or more predetermined system conditions that have a high probability of causing unusual stress on the power system, and for which preplanned remedial action is considered necessary. The failure of these schemes to accurately detect the defined conditions, or their failure to carry out the required preplanned remedial action, can lead to very serious and costly power system disturbances. It is natural, therefore, that a concern for the reliability of these schemes has been expressed. On this basis, this paper analyzes the reliability of SPS and ensures its outcome with an acceptable probability.

2014 Power Systems Computation Conference, 2014

A new methodology is presented, allowing to evaluate protection systems reliability and availability indexes, taking into account equipment failure and repair rates. The protection scheme is translated into a reliability graph, enabling to identify all possible logical occurrences in the system, either meaning failure or successful operation. Evaluation of the system reliability and availability indexes is achieved by Monte Carlo simulation. The methodology is applied to a typical transmission line protection bay, for different time to repair scenarios, and conclusions on asset management options are drawn.

System Reliability, 2017

This chapter provides an overview of the reliability of electricity distribution networks, and its evaluation that is linked with the protection system. In this way, the characteristics of network protection are presented, along with the peculiarities in coordination and device selectivity adjustments. For the assessment of the reliability, we have the methodology of logic-structural matrix (LSM) that integrates the constitution of the network with historical data of faults, so that with this, a model can be elaborated that can evaluate the impact of changes in the system directly on the reliability indicators.

Springer eBooks, 2013

Relays are widely used in power distribution systems to isolate their faulty components and thus avoid disruption of power and damaging expensive equipment. The reliability of relay-based protection of power distribution systems is of utmost importance and is judged by first constructing Markovian models of individual modules and then analyzing these models analytically or using simulation. However, due to their inherent limitations, simulations and analytical methods cannot ascertain accurate results and are not scalable, respectively. To overcome these limitations, we propose a modular approach for developing Markovian models of relay-based protected components and then analyzing the reliability of the overall power distribution system by executing its individual modules in parallel using the PRISM probabilistic model checker. The paper presents a foundational model for a relay-based protected component that can be incrementally updated to represent more advanced behaviors, such as self-checking, routine test and continuous monitoring. Moreover, the paper provides a set of reliability assessment properties of power distribution systems that can be formally verified by PRISM. For illustration purposes, we present the analysis of a typical power distribution substation.

Electric Power Systems Research, 2015

A performance analysis methodology for transmission line primary protection systems is presented, based on a probabilistic approach to protection system successful operation. The protection system operation is represented by reliability graphs, and a probabilistic model of the distance protection is considered. The system successful operation is described by tie-sets, and solutions are obtained from Monte Carlo simulation. The system elements are characterized by the reliability factors: equipment failure rate and time to repair. The system performance is assessed by the availability index. The developed methodology is applied to a transmission line protection scheme with one aided communication channel. Results allow quantifying the influence of the fault location on the protection system performance. Results also show the influence of the equipment failure rate on the system performance. The developed methodology proves to be adequate to quantify the benefits of using communication channels in transmission line protection. Furthermore it is adequate to assess different protection system architectures. A comparative performance analysis, considering four different transmission line protection schemes, can be found in the Part II paper.

Power Systems and Power Plant Control 1989, 1990

2010

This paper describes a protective relay for fast and reliable transmission line protection that combines elements that respond only to transient conditions with elements that respond to transient and steady state conditions. In this paper, we also present an algorithm that prevents Zone 1 distance element overreach in series-compensated line applications and show how to prevent corruption of the distance element polarization during pole-open conditions. We also introduce an efficient frequency estimation logic for single-pole-tripping (SPT) applications with line-side potentials. This logic prevents distance element misoperation during a system frequency excursion when one pole is open. We also discuss an algorithm and logic to prevent single-pole reclosing while the fault is present, avoiding additional power system damage and minimizing system disturbance. Applying these algorithms and logics results in a protective system suitable for increasing power system requirements such as heavy loading, SPT, series line compensation, and shunt line compensation.

When two or more lines are running parallel to each other, mutual impedances between the lines modify the voltage and current profile measured in the protective relays protecting each line. Analysis of transmission line impedance formulas can provide interesting data to the protection engineer. Fault location is an algorithm in protective relays that reports the distance to the fault. Ground fault location is discussed, as is the implication of requiring the measurement of the parallel line 3I0 for a more accurate calculation. Since the algorithm is slow and done after the trip decision, the 3I0 measurement does not necessarily have to be sampled in the same box. Protective relaying considerations for preventing overreach and loss of directionality under certain power system operating conditions are illustrated and discussed. The paper illustrates the benefit of measuring I0p (the parallel line zero-sequence current) for fault location. d Fernando Calero has a BSEE (86) from the University of Kansas, Lawrence KS, an MSEE (

IEEE Transactions on Power Delivery, 2019

The increasing proliferation of distributed generators (DGs) demands a robust and comprehensive design of the communication-based adaptive protection scheme which must be able to deal with not only the known changes in the DGsdistribution system but also be able to handle the unknown changes due to variations in the operating mode, network configuration, and number, type, and size of DGs. On one side, with the increasing installations of DGs, the deployment of the communication system in protection is increasing to monitor the system status and select the relays' settings accordingly. However, on the other side, if information flow doesn't happen due to the presence of pre-fault failure of the relay-agents and/or communication links, a protection scheme may fail to provide the suitable protection. This paper proposes a centralized adaptive protection scheme to deal with such failures and varying operating conditions. It provides optimal relays settings for varying operating conditions of the DGs-distribution system with the aim of providing fast, comprehensive, and self-adaptive protection. In order to achieve these objectives, two algorithms have been developed: the first algorithm determines optimal hybrid pickup settings of the relays, and the second algorithm determines the adaptive hierarchies of the relays. With the inclusion of these two algorithms, the relay coordination problem has been formalized linearly. The performance of the proposed scheme has been tested and validated for various known and unknown events with different types of short circuit faults of different fault impedances on the 37-bus IEEE test distribution system in a MATLAB simulation and coding environment. The results show that the proposed method not only provides the optimal relay's coordination in varying situations but also effectively reduces the protection latency due to pre-fault failures of the relays and communication links, and low level of fault currents.