A method of creating distance protection relays using field programmable analog arrays.

摘要

Power system and its related elements always face the danger of faults and abnormal conditions. Protective relays are designed to respond to faults on specific power apparatus, thus protecting the faulted apparatus from damage and the power system from instability. Protective relays have been designed with different technologies resulting in electromechanical, solid-state (analog) and numerical relays.;Speed and reliability are the two most important characteristics of a protective relay. Other capabilities such as monitoring and recording are supposed to be of secondary priority. Without any doubt, present-day numerical relays provide considerable capabilities and advantages but they have not improved the speed of operation in comparison to their solid-state counterparts. As system restructuring is reducing power system reserve margins and endangering system stability, the speed, reliability and performance of protective relays have become more critical.;In a power system, currents and voltages at different points are measured and scaled down using voltage and current transformers, and these analog signals are applied to protective relays. Protective relays, by processing these signals, detect faults in the system and send appropriate signals to actuate circuit breakers or to other relays to isolate faulty apparatus.;Normally, the main protection function of protective relays is not complicated and it is a combination of simple basic operations such as filtering, adding, subtracting, scaling and comparing. Therefore, use of digital technology in numerical relays has not provided major benefits for main protection function. Nevertheless, it has provided remarkable advantages in peripheral features of protective relays such as data recording, monitoring and communication.;Present-day numerical distance relays could achieve similar or better performance than their old solid-state and electromechanical counterparts in many aspects of protection. However, some weaknesses in certain aspects exist when compared to their solid-state counterparts. As a result, the idea of using hybrid relays to achieve the advantages of both analog and digital technologies seems worthwhile to be researched if better analog technology becomes available.;With advancements in analog technology which has become more advanced recently, the idea of using mixed signals in several applications has started. In addition, production and development of FPAAs (Field Programmable Analog Arrays) have grown rapidly and right now they provide enough capabilities to be used in protective relays. The new technology using combination of FPAAs and digital technologies seems to be a breakthrough and has the potential to provide better performance than the present-day numerical relays. In this thesis, use of FPAAs for designing and implementing distance relays is investigated for the first time in literature. A novel technique of creating distance relay and its hardware implementation using FPAAs is described. Test results are reported. The proposed relay achieves a reduction in the operating time of the distance protection especially for high resistive and high SIR systems. The maximum operating of the FPAA-based relay is considerably lower than an advanced commercial relay resulting in savings and better stability margin. A separation in the hardware implementation of main protection functions and other functions is utilized in the FPAA-based relay which may result in higher reliability. The proposed relay achieves simplicity in implementation of distance relay and CVT transient supervision.