Power Systems for Wide-Area Backup Protection Scheme

The evolving wide-area measurement system technology offers new opportunities for backup protection of transmission lines to avert the misoperation of conventional relays against system disturbances and prevent system instability. Since wide-area backup protection (WABP) is to operate at the range of a few hundred milliseconds, the delays associated with data and command communications and algorithm execution can be a troublesome issue in a large-scale power system. This paper briefly reviews a WABP scheme based on positive-sequence voltage phasor direct and indirect measurements.

To overcome the problem of WABP delays, an integer linear programming (ILP) model is proposed to divide the power system into several protection regions. This process is accomplished in three stages in which the number and location of measurement devices (MDs), the number and boundary of protection regions, and the location of protection rooms, as well as the total number of communication links between MDs and protection rooms are optimized. The proposed WABP scheme is implemented in each region and individually protects the associated transmission lines. Execution of the proposed ILP model on different test systems reveals that with regionalization of the systems, WABP schemes can reliably be used in practice.