Integrated Adaptive Reach Setting of Distance Relaying Scheme in Series Compensated Lines

Abstract

Abstract:The protection of series compensated lines is considered to be one of the most difficult tasks. The paper reviews the series compensated line protection challenges initially and presents state of art solution to improve the distance relay performance. The work describes the development and evaluation of an integrated adaptive distance protection scheme. Development of the adaptive scheme is in the specific area of incorporating the adaptive feature like adaptive reach setting of the relay as the compensation level changes in the series compensated lines, for optimum dependability and security of the protection system. The relay adapts its characteristics according to the informations received from the communication unit. Upon extensive testing on different data set of fault cases with fault resistance and varying percentage compensation level and fault location , performance of the developed method ensures that the proposed scheme overcomes the overreach/underreach problem of the distance relay in series compensated lines and is found to be quite promising.Index Terms: Adaptive Distance Relay, Adaptive relaying scheme, Digital distance relay, Full Cycle Fourier Transform, Series compensation. IntroductionSERIES compensation plays the vital role in modern heavily loaded grid transmission lines. The series capacitor makes sense because it is simple and could be installed for 15 to 30% of the cost of installing a new line. Series compensation in modern power systems influences the power flow in particular network segment, reduces active power losses prevents system and sub synchronous oscillations, and connects more robustly different subsystems to stronger integrated network .The introduction of series compensation in existing networks requires not only extensive studies into the expected performance of the new system but also into the influence of its introduction on the operation of existing protection control and monitoring systems.The introduction of the capacitance in series with the line reactance adds certain complexities to the effective application of impedance based distance relays. The protective distance relays, which make use of impedance measurements in order to determine the presence and location of faults, are "fooled" by installed series capacitance on the line when the presence or absence of the capacitor in the fault circuit is not known priori. Manuscript received on July 14. 2010.S. G Srivani is with the National Institute of Technology Surathkal, Karnataka, India. (e-mail:abc_sgs@yahoo.com.) K. P. Vittal, professor, is with the National Institute of Technology Surathkal, Karnataka, India. (e-mail: vittal_nitk@yahoo.com.).Series Capacitors(SCs) and their overvoltage protection devices (typically Metal Oxide Varistors (MOVs) and/or air gaps), in spite of their beneficial effects on the power system performance, introduce additional problems and make the operating conditions unfavorable for the protective relays that use conventional techniques and include phenomena such as voltage and...

Series Compensated Transmission Line Protection Using Pscad

“…It is very difficult task to handle series compensated line during various abnormalities with relay settings. The introduction of the series capacitance in the lines adds many complexities to the effective performance of distance relay [1]. The relay will try to look at the ratio of voltage and current to determine the distance to fault in order to decide if the fault is in its own zone or out of its protection zone.…”