Reliability evaluation of transmission network including effect of protection systems

Abstract

SUMMARYTransmission network reliability evaluation considering effects of protective systems is investigated in this paper. Protective system faults are one of the main sources of cascading outages and may lead to vast blackouts. Desired performance of the protection system has a significant role in the improvement of network reliability. The proposed method is based on minimal cutset approach. In the proposed method, all elements of the transmission and subtransmission substations can be considered in which subtransmission substations are taken as output nodes. A sensitivity analysis of network reliability to component reliability parameters is performed. Finally the effectiveness of the method was tested in a real network with satisfactory results.

A new risk assessment method of power system distance protection

“…where, for the starting element based on fault superimposed component of current, I m is the RMS of the fault superimposed component of current Δi φφ shown in (3). The corresponding threshold value, I set , is shown in (4).…”

“…Compared with , the starting intercept, the fault identification intercept and the measuring intercept, closely combined with specific protection principles, could automatically distinguish the normal operation and fault scenarios, and guide the risk assessment process without human intervention. The consequence measurement of relay failures, including the change of node voltages, the overload, and the load loss, is more comprehensive for achieving the online monitoring of protection systems.…”

“…Consequently, despite the excellent R&D capacity of protective device manufacturers and the use of reclosers improving the stability of power transmission systems, the reliability of protection systems still needs to be reinforced to adapt the rapid development of power systems. Advanced technologies and theories should also be fully utilized to provide support for assessing the operating risk of protection systems, and monitoring their operating level and hidden troubles .…”

Directional ground relay failure caused by line‐to‐ground with load‐side broken conductor fault

“…In fact, it can be used to study radial or meshed networks, passive or active loads, and ungrounded, grounded or resonant‐grounded systems . Using the SCT, a sinusoidal condition is considered, and phasor algebra is applied .…”