Sparse Network Equivalent Based on Time-Domain Fitting

Abstract

Abstract-The paper presents an approach for network equivalent calculation for the analysis of electromagnetic transients in power systems. It is based on time-domain fitting and enforces some degree of sparsity while preserving the accuracy of the equivalent. The calculated equivalent is appropriate for direct interface with the rest of the system in time-domain. A constrained least squares solution of the time-domain fitting equations is used to ensure accuracy at 0 and 60 Hz. Results demonstrating the accuracy and computational efficiency of the method are presented.

Robust phase-domain transmission line representation based on time-domain fitting

“…For the four-port case, in the z-plane, voltages and currents are related according to: (10) Here, all elements of the admittance matrix Y(z) are rational functions sharing the same poles, i.e. the same denominator 2 a(z): The first term of a(z) is assumed to be equal to 1 and note that k in b k ij is not an exponent; it only identifies the coefficient of z −k .…”

“…In matrix R, I n m is a submatrix built using the data from i n m as in (8) and V n is a submatrix of voltage as in (9). The dimension of R is 6N × (p + 6(p + 1)).…”

“…The methodology used here is an extension of the one reported in refs. [9][10][11] for modal-domain network equivalents. A polynomial matrix in the z-domain describes the resulting model.…”

“…The poles, as proposed in[9][10][11], were assumed to be the same which makes easier to enforce stability (see Section 4.1).…”

Reassessment of Permissible Negative Sequence Current for Power Plant Operation of Taipower

“…In this paper, the EMTP was used to evaluate NSC levels from the four out-linking untransposed overhead 345-kV transmission circuits [14][15][16][17][18][19]. The models of EMTP were corrected by measurement data from the wide area measurement systems (WAMS).…”