Abstract
The Lumped Parameter Model (LPM) is a known approach to represent overhead transmission lines (TLs), especially when these elements comprehend a few tens of kilometers. LPMs employ a large number of cascaded π-circuits to compute accurately the transient responses. These responses contain numerical spurious oscillations (NSO) characterized by erroneous peaks which distort the transient responses, mainly their peak values. Two modified LPM topologies composed of damping resistances inserted along the longitudinal or transversal branches of the cascaded π-circuits offer significant mitigations in the NSO. In this paper, in an effort to have the maximum mitigation of the NSO and low distortion in the transient responses, two modified topologies with optimized damping resistances are proposed to represent short TLs. Results demonstrate expressive attenuation in the peaks of NSO which reflect good agreement in comparison with the responses computed by the Bergeron’s line model. The mitigation of the NSO is carried out directly in the time domain and it does not require either analog or digital filters.Furthermore, no frequency-to-time transformations are necessary in this procedure. These alternative topologies can be incorporated into any electromagnetic transient program to study switching operations in power systems.
Highlights
Lumped Parameter Model (LPM) are employed to simulate electromagnetic transients in many conditions, such as (i) for switching maneuvers for which frequency content varies from 50/60 Hz up to 20 kHz [2,4]; (ii) when nonlinear loads are connected in the power system; (iii) when fault currents are in different locations along the line; (iv) when Corona effect must be included in the analysis [5]
In order to investigate the performance of the modified topologies in the transient responses, concerning the maximum attenuation of numerical spurious oscillations (NSO) with the lowest distortion, this paper presents a methodology to compute the best adjustable factors for each modified topology based on the LPM
The numerical results are divided into three sections organized as follows: in Section 5.1, the frequency responses of the modified topologies are compared to those obtained by the traditional LPM
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. In order to investigate the performance of the modified topologies in the transient responses, concerning the maximum attenuation of NSO with the lowest distortion, this paper presents a methodology to compute the best adjustable factors for each modified topology based on the LPM These adjustable factors depend on the line length and number of π-circuits/km, where fitted 3-D surface equations are obtained using Curve. The modified topologies with the best adjustable factors can be incorporated into EMT-type programs in which neither digital nor analog filters are required since the filtering process is carried out directly in the time domain This procedure is very advantageous due frequency-to-time domain transformations such that Fourier transforms are not necessary.
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