Distribution system short circuit analysis-A rigid approach

A Fortescue Approach for Real-Time Short Circuit Computation in Multiphase Distribution Networks

“…The Fortescue SCC approach was tested on three standard test feeders (IEEE 13-node, IEEE 34-node, IEEE 123-node) in addition to four practical test networks having 1505, 2986, 8500, and 14 200 nodes; it was compared with an implementation of the classical canonical SCC method in phase coordinates [7], where the unity current injection method was used in computing the Thévenin impedance matrix and the post-fault voltage vector [4]. Distributed loads were modeled by two spot loads at each end of the line following the approach in [14].…”

“…In fault simulations however, voltage levels fall well below the nominal range and loads switch to constant impedance models [1], [4]. Starting from the complex power consumption, the three-phase, two-phase, and one-phase loads are converted to admittances at nominal voltage (or the voltage from the distribution system power flow results) and then transformed into the Fortescue domain-similar to the development in (2), (5), and (8).…”

“…Additionally, the generator and transformer modeling in terms of symmetrical components is relatively simple, and the power component data is usually available in terms of sequence values. Short circuit computation (SCC) is a real-time application in modern distribution networks [3], [4]; it is employed for the identification of fault locations and for performing checks on the protection system, possibly involving an update of relay settings, prior to implementing feeder reconfiguration.…”

“…There have been several more recent and notable contributions that also make use of fault analysis in phase coordinates, for instance, the canonical model in [7] and Kersting's approach [8]- [10]; both of these methods employ source superposition, which has emerged as the more popular alternative in comparison with the distributed-source methods particularly due to computational advantages. The Generalized Distribution Analysis System [4], also based on superposition, is oriented towards applications in distribution system operation by employing the unity current injection method for computing both the Thévenin impedance matrix and the post-fault voltage vector. Nevertheless, the distributed-source method was also investigated in [11], where it was argued that the effect of modeling metallic (zero impedance) faults using small resistances could result in calculation errors; the accurate solution is along the lines originally proposed in [6] and involves solving the normal system of equations subject to a number of boundary constraints, which is also equivalent to modifying the nodal admittance matrix to obtain a number of reduced equations for solution without constraints.…”

“…Section IV introduces the Fortescue SCC in multiphase networks, and Section V presents the boundary conditions for short circuit modeling of multiphase nodes; a demonstration example of the procedure is given in Section VI. Numerical results in Section VII serve to establish the validity of the Fortescue SCC by comparing with the classical canonical approach in phase coordinates [4], [7]; additionally, Section VII reports computational performance comparisons on large-scale SCC instances. The paper is concluded in Section VIII.…”