On‐line short‐circuit current analysis and preventive control to extend equipment life

Abstract

Substation circuit breakers and other equipment are sized to withstand the maximum anticipated short-circuit currents. Although the short-circuit analysis used to design a substation takes into account the expected expansion of the network, over time the maximum short-circuit current, especially for certain operating conditions, can exceed the circuit breaker ratings. As upgrading the equipment is expensive, the life of the present equipment can be extended if these violation conditions can be identified in real time and operational actions taken to mitigate them. In this study, the authors present a method for online short-circuit analysis and a method for determining preventive action using transmission line switching.

Three-Dimensional Finite-Element Analysis of the Short-Time and Peak Withstand Current Tests in Substation Connectors

“…From Equation (2), it is deduced that by a tight control of the voltage phase angle θv during the making instant, the peak value of the transient short-circuit current can be changed from I0 to 2I0. For example, when θv = ϕ the DC component term in Equation (2) is null and thus the peak value of the current results in I0.…”

“…Conversely, when θv = ϕ + 90°, the dc term is maximum, and the peak value of the current is 2I0. Figure 1 shows the short-circuit current as described by Equation (2). It is worth noting that substation connectors and other electrical devices must be designed to safely withstand their associated rated short-time and peak withstand currents, that is, without causing any mechanical damage to their components.…”

“…Conversely, when θ v = ϕ + 90˝, the dc term is maximum, and the peak value of the current is 2I 0 . Figure 1 shows the short-circuit current as described by Equation (2).…”

“…Due to the fast expansion of transmission systems worldwide, power networks are becoming more complex and dense. Short-circuit currents are increasing, thus increasing the risk of damage because they can exceed the breaking capacity of the electrical protections in the networks [2]. Since short-circuits in power systems can lead to severe faults [3], it is crucial to ensure that the fault currents are below the safety limits of the equipment involved.…”

Fast electro‐thermal simulation of short‐circuit tests

“…Power transmission systems are expanding due to the increasing consumption of electrical power worldwide [1]. Short‐circuit fault current levels in power systems are raising [2], which can produce severe faults due to both the unusual thermal and mechanical stress the components have to withstand, thus increasing the risk of power system failure [3]. Therefore, it is essential ensuring that fault currents do not compromise the safety limits of the involved electrical equipment.…”