Protection of transmission lines pdf

This paper describes different cases of parallel transmission lines and analyzes some well known application problems associated with their protection. Distance protection performance problems are in the focus due to the fact that they are the most commonly used protection type for parallel transmission lines. The protection currently applied to HVDC transmission lines still has disadvantages such as low tolerance to transition resistance, poor reliability, and susceptibility to lightning interference. Therefore, improving the reliability of DC transmission line protection is of great significance to the stable operation of the power system. 2. EHV Transmission Line Protection Whitepaper 4 W E S T E R N E L E C T R I C I T Y C O O R D I N A T I N G C O U N C I L Model Power System The Specifier may request that the manufacturer demonstrate the performance of its relay system by model power system testing. The Specifier has the option to require testing one complete system of a Protection of March 1 2013 Transmission Lines using GPS This is a new technique for the protection of transmission systems by using the global positioning system (GPS) and fault generated transients. In this scheme the relay contains a fault transient detection system together with a communication unit, which is connected to the power line This is a new technique for the protection of transmission systems by using the global positioning system (GPS) and fault generated transients. In this scheme the relay contains a fault transient detection system together with a communication unit, which is connected to the power line through the high voltage coupling capacitors of the CVT. We are able to use differential protection along with GPS to provide protection for transmission lines even though they cover long distance. GPS can provide synchronized measurements of currents on both sides of transmission lines with time stamped. Fiber optic can be considered for data communication. protection schemes used on non-compensated transmission lines. Once these basic principles are understood, an attempt can be made to expand on them in order to solve the additional relaying problems caused by the introduction of the series compensation capacitors. 1.1 Commonly Used Methods Available for Distance Protection of Transmission Lines Transmission line model CO3301-3A Resistive load CO3301-3F Equipmentnt Overcurrent time protection relay CO3301-4J Multimeter. Protective device in a branch Also of relevance to protection of lines (underground cables / overhead lines) are the transmission distance and type. In high voltage networks with low resistance, neutral- Figure 5. Link between source to transmission line ratio and protection relay voltage (a) Electrical power system arrangement (b) Change in protection relay voltage with electrical system source to transmission line impedance ratio The universal relationship between V. R . and Z. S /Z. L, presented in Figure 5, is valid for all This is a special report of the IEEE - Power System Relaying Committee Justifying Pilot Protection on Transmission Lines - 1/8/2008 Page 2 line current differential (LCD): Remote and local terminal currents or composite currents are summed via data shared over fiber or other communication media. and currents respectively. Thus back up protection is also obtained for the system. Also hybrid relay trip signals can be derived and can ensure com