scholarly journals Transient Analysis of Multiphase Transmission Lines Located above Frequency-Dependent Soils

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5252
Author(s):  
Tainá Fernanda Garbelim Pascoalato ◽  
Anderson Ricardo Justo de Araújo ◽  
Pablo Torrez Caballero ◽  
Jaimis Sajid Leon Colqui ◽  
Sérgio Kurokawa
Keyword(s):  
Power Systems ◽  
Frequency Dependence ◽  
Transmission Lines ◽  
Transient Analysis ◽  
Transient Responses ◽  
Frequency Dependent ◽  
Lightning Strikes ◽  
Significant Difference ◽  
Soil Conductivity ◽  
The Impact

This paper evaluates the influence of frequency-dependent soil conductivity and permittivity in the transient responses of single- and double-circuit transmission lines including the ground wires subjected to lightning strikes. We use Nakagawa’s approach to compute the ground-return impedance and admittance matrices where the frequency-dependent soil is modeled using Alípio and Visacro’s model. We compare some elements of these matrices with those calculated by Carson’s approach which assumes the frequency constant. Results show that a significant difference can be obtained in high resistive soils for these elements in impedance and admittance matrices. Then, we compute the transient responses for single- and double-circuit lines with ground wires located above soils of 500, 1000, 5000, and 10,000 Ω·m considering the frequency constant and frequency-dependent parameters generated for two lightning strikes (subsequent stroke and Gaussian pulse). We demonstrate that the inclusion of frequency dependence of soil results in an expressive reduction of approximately 26.15% and 42.75% in the generated voltage peaks in single- and double-circuit lines located above a high-resistive soil. These results show the impact of the frequency-dependent soils that must be considered for a precise transient analysis in power systems.

scholarly journals Frequency-dependent fitness induces multistability in coevolutionary dynamics

2012 ◽  
Vol 9 (77) ◽  
pp. 3387-3396 ◽  
Author(s):  
Hinrich Arnoldt ◽  
Marc Timme ◽  
Stefan Grosskinsky
Keyword(s):  
Frequency Dependence ◽  
Evolutionary Dynamics ◽  
Metastable States ◽  
Theoretical Research ◽  
Nonlinear Frequency ◽  
Frequency Dependent ◽  
Switching Dynamics ◽  
Game Theoretic ◽  
System Properties ◽  
The Impact

Evolution is simultaneously driven by a number of processes such as mutation, competition and random sampling. Understanding which of these processes is dominating the collective evolutionary dynamics in dependence on system properties is a fundamental aim of theoretical research. Recent works quantitatively studied coevolutionary dynamics of competing species with a focus on linearly frequency-dependent interactions, derived from a game-theoretic viewpoint. However, several aspects of evolutionary dynamics, e.g. limited resources, may induce effectively nonlinear frequency dependencies. Here we study the impact of nonlinear frequency dependence on evolutionary dynamics in a model class that covers linear frequency dependence as a special case. We focus on the simplest non-trivial setting of two genotypes and analyse the co-action of nonlinear frequency dependence with asymmetric mutation rates. We find that their co-action may induce novel metastable states as well as stochastic switching dynamics between them. Our results reveal how the different mechanisms of mutation, selection and genetic drift contribute to the dynamics and the emergence of metastable states, suggesting that multistability is a generic feature in systems with frequency-dependent fitness.

Role of inertia in the measurement of dynamic compliance

1975 ◽  
Vol 38 (1) ◽  
pp. 64-69 ◽  
Author(s):  
J. Dosman ◽  
F. Bode ◽  
J. Urbanetti ◽  
R. Antic ◽  
R. Martin ◽  
...  
Keyword(s):  
Frequency Dependence ◽  
Dynamic Compliance ◽  
Age Group ◽  
Older Individuals ◽  
Breathing Frequency ◽  
Frequency Dependent ◽  
Younger Age ◽  
Significant Difference ◽  
Males And Females

Dynamic compliance (Cdyn) was measured at different frequencies (breaths/min) in 30 nonsmoking males and females aged 30–59 yr. In those aged 30–49 yr Cydn at 90 breaths/min was significantly higher than at 15 breaths/min while those aged 50–59 yr showed no significant difference. Assuming an inertance of 0.01 cmH2O/l per s-2, and a sinusoidal breathing frequency, Cydn at 60 and 90 breaths/min was corrected for inertia. In the 30–49 yr age group corrected Cydn did not change with increasing frequency of breathing whereas in the 50–59 yr age group Cydn at 15 breaths/min was significantly higher than at 90 breaths/min (P is less than 0.05). In this age group, four of eight subjects were frequency dependent when corrected for inertia. These findings indicate that inertia influences Cydn at breathing frequencies of 60 per min and above. Unless this is taken into account, frequency dependence of compliance may be missed. The results also indicate that frequency dependence of compliance is normal in some older individuals but is not normal in the younger age group.

scholarly journals Optimization of Lumped Parameter Models to Mitigate Numerical Oscillations in the Transient Responses of Short Transmission Lines

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6534
Author(s):  
Jaimis S. L. Colqui ◽  
Anderson R. J. de Araújo ◽  
Sérgio Kurokawa ◽  
José Pissolato Filho
Keyword(s):  
Power Systems ◽  
Transmission Lines ◽  
Lumped Parameter Model ◽  
Transient Responses ◽  
Lumped Parameter ◽  
Lumped Parameter Models ◽  
Spurious Oscillations ◽  
The Time Domain ◽  
Time Transformations ◽  
Good Agreement

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.

Sign in / Sign up

Export Citation Format

Share Document