Transmission Protection

RTE - Transmission Line Protection (Issues and Solutions)

RTE is the French Transmission System Operator. It operates a network comprising approximately 100 000 km of lines and 2450 substations. Almost half of the lines correspond to the transmission level (400 kV and 225 kV) including the interconnections to the neighbor countries, the other half belong to the regional sub-transmission level (90 kV and 63 kV). Today, RTE operates approximately 16,000 line protection relays, 15% of which are digital.
RTE has elaborated a set of documents used as reference for the protection of all network components. The protections to be used are defined depending on the voltage level, the component to be protected and its characteristics (underground or overhead lines, busbar, transformers, etc.) and the importance of this component in the network. More

ESKOM - Transmission Line Protection Issues and Their Solutions

One of the main challenges currently being faced is an increase in the number of high resistance faults which fall outside the capability of the impedance protection. The current solution being considered is to apply direction earth-fault comparison protection as an additional protection function. More

Western Power Transmission Line Protection Design and Philosophy

Western Power is the state-owned utility of Western Australia and operates various voltage levels in Transmission and Distribution network. Transmission voltages include 66KV to 330KV covering a large area connected through the network (South West Interconnected System-SWIS). It contains around 88000 km of power lines with load around 3600MW.  The complete scheme for 220KV and 330KV lines consists of duplicated, fully independent and discriminative protections capable of providing high-speed fault clearance over the entire line length. These protections may be either unit types, such as differential, phase comparison, or distance with tele-protection signaling (using direct or permissive transfer tripping). More

Brazilian Transmission Line Protection Issues and their Solutions

The main issue related to transmission line protection seems to be the large number of specific cases. The Brazilian electric system is singular due to its large geographical area, supplied mainly by hydro power plants located on rivers far from the load centers. The main generation source is Itaipu, a bi-national (Brazil & Paraguay) power plant with an installed capacity of 12,600 MW. Large portions of the Brazilian territory, mainly on the Amazon region, remain attended by isolated thermal systems, with scarce transmission resources. At the other extreme, highly dense load centers are located on main industrial and metropolitan areas on the Atlantic coast. The main transmission corridors and international connections of this system cover an area superior to that of the whole Western Europe. More

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