2013. — 8 с.High-speed unit protection is an essential requirement for efficient operation of transmission and sub-transmission systems. In the event of a fault, the protection must isolate quickly the faulted circuit to prevent damage and enhance the stability of the system. For line protection, two types of main protection are common: current differential and distance protection. The former has a dedicated signaling channel carrying the special current vector messaging between line ends, while the latter traditionally relies on teleprotection equipment external to the main protection relays. For distance applications there is thus much scope for improving the unit protection performance, by allowing the relay to connect directly to the signaling channel available between line ends, rather than using conventional binary inputs and output contacts to signal via other intermediate equipment. However, communications devices are still widely used.
High-speed fault clearing for different faults on transmission lines can be achieved by advanced communications based protection schemes.
The paper describes as an example a directional comparison protection scheme and discusses possible implementations using high-speed peer-to-peer communications to achieve the accelerated protection scheme.
Direct relay-to-relay communications allow significant reduction in the overall cost of accelerated transmission line protection schemes. At the same time they reduce the total operating time of the protection for any fault within the zone of protection.
The paper discusses the impact of IEC 61850 and how the high-speed peer-to-peer GOOSE (Generic Object Oriented Substation Event) messages can be used to replace proprietary communications or the hard wiring between the different devices used in such distributed protection scheme. The overall performance of the protection system is analyzed and requirements and methods for testing are later discussed. Line differential protection is out-of-scope of this paper
