Power system stabilizer design using fuzzy logic

Bibliography: p. 104-108

Transmission line directional protection using neural networks and filtering algorithms

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A Comprehensive Survey on Islanding Detection Methods of Synchronous Generator-Based Microgrids: Issues, Solutions and Future Works

Nowadays, the penetration of distributed generations (DGs) and microgrids (MGs) has been significantly increased due to the technical, social, environmental, and financial reasons. One of the most common types of DGs which is widely used in different networks is small-scale synchronous generators (SSSGs). Synchronous-based microgrids (SGBMGs) and SSSGs can operate under both grid-connected and islanded conditions. To guarantee a stable, uninterruptible, and safe autonomous operation, the unintentional islanding events should be quickly detected and then, appropriate control and precaution actions should be performed. Various islanding detection techniques have been proposed in the two past decades including remote and local methods. Meanwhile, local methods can be divided into two major groups, i.e. passive and active methods. To select the most suitable islanding detection scheme (IDS), various factors including the DG type and its technology should be considered. Therefore, the IDS for SGBMGs may be completely different from that for inverter-based microgrids. In this paper, the suitable IDS which can be practically applied to the SGBMGs are comprehensively investigated. To do so, at first, various suitable indices are introduced which can be properly employed by the system engineers and researchers to compare various IDS and select the most appropriate one. Then, various types of existing IDS are carefully investigated using these indices. Based on these investigations, it is concluded that local passive methods are more appropriate for SGBMGs due to their technical and economic benefits. Moreover, to enhance the existing IDS, some ideas are provided in this paper which can be considered in the future research works

An Accurate Non-Pilot Scheme for Accelerated Trip of Distance Relay Zone-2 Faults

The delayed operation of distance relays zone-2 element for the faults at the end of the line is excessive. It reduces the fault clearing speed and therefore, is one of the main factors that can endanger power system stability. This paper proposes an impedance-based scheme for discrimination between the last 20% of the line length faults and the adjacent line faults, which are covered by the relay zone-2. The suggested non-pilot scheme uses a modified fault location formula for the accelerated zone-2 operation of distance relays. The negative- and zero-sequence components of local signals are utilized to calculate the accurate fault location after the remote circuit breaker (CB) operation. The proposed algorithm is independent of fault resistance, power flow direction, pre-fault condition, and it can clearly distinguish internal faults from the adjacent line faults. Simulation results show that the proposed method can identify the remote CB operation and thus can accelerate the tripping of zone-2 within a very short time for different fault locations, fault types, fault resistances, and load angles. Also, accurate fault location has been achieved under all simulation conditions. 1986-2012 IEEE.Manuscript received December 7, 2019; revised March 12, 2020, May 20, 2020, and July 1, 2020; accepted July 3, 2020. Date of publication July 7, 2020; date of current version May 21, 2021. This work was supported in part by the National Priorities Research Program under Grant 11S-1125-170027, and in part by the Qatar National Research Fund (a member of Qatar Foundation). (Corresponding author: Amir Ghorbani.) Amir Ghorbani is with the Department of Electrical Engineering, Ab-har Branch, Islamic Azad University, Abhar 4561897594, Iran (e-mail: [email protected]).Scopus2-s2.0-8509911653

Accelerated distance protection for transmission lines based on accurate fault location

The accelerated operation of distance relay is an important issue to improve the power system stability. The zone-1 of distance relay usually covers about 80% of the transmission line length with an instantaneous operation, while during resistive faults the coverage of zone-1 may be reduced considerably. Therefore, the conventional distance relay cannot cover the whole line length with fast fault clearance. To address the above problem, a non-pilot protection scheme based on the accurate fault location estimation is proposed. When a fault occurs at the end section of the line, after the fast remote circuit breaker (RCB) operation, the accurate amount of fault current can be obtained. Using this current, the accurate fault location is calculated, and as a result, the accelerated trip can be issued to the local circuit breaker (CB) for the faults occurring at all the total line length including the end section faults. The obtained fault location formula is independent of the fault resistance and remote source impedances and can be applied to both single- and three-pole CB operation modes. The proposed high-speed protection scheme is evaluated in the WSCC 9-bus system. Numerous PSCAD simulation studies verify the effectiveness and applicability of the proposed scheme. 2021This work was supported by the National Priorities Research Program under Grant 11S-1125-170027 from the Qatar National Research Fund (a member of Qatar Foundation). The authors would like to sincerely thank Mr. Habib Panahi for his help and comments.Scopus2-s2.0-8509916939