Fault simulation in networks with isolated neutral to find the fault location in power transmission lines

The paper deals with an urgent problem - determining the location of damage to an overhead power transmission line. In particular, the application of the wavelet transform is considered, which makes it possible to localize the temporal position of the frequencies and to determine the time interval of the presence of the frequency in the event of damage to the power line. The paper presents a mathematical model that makes it possible to determine the amplitude-frequency spectrum, by which it is possible to determine the presence of a certain frequency in the signal under study, by which it is possible to determine the fault location. Based on the wavelet transform, the spectra of the current and voltage in the damaged phase in the isolated neutral mode are obtained. It is shown that when the neutral mode is switched, there are no dangerous overvoltage or current surges in the network, and the overvoltage level is reduced.

Method for automatic compensation of a single-phase earth fault

The paper demonstrates improving the reliability of power supply and operating safety of power receivers in electric networks of 6-10 kV, by controlling the neutral mode in extended electric networks of 6-10 kV with capacitive earth fault currents above 15 A. The purpose of the study is to increase the reliability of power supply and the safety of operation of power receivers in such electric networks, the establishment of patterns in controlling the neutral mode in extended 6-10 kV electric networks with capacitive earth fault currents above 15 A, as well as the development of a method and device automatic detection of single-phase earth fault current. Grounding methods and neutral modes in electric networks with a voltage of 6-10 kV are considered. The method and device for automatically determining the current of a single-phase earth fault were developed. In the result, the relationship between the active and inductive components of the neutral current during series RL grounding of the network Ia/IL=(0.5÷0.3) was established, which ensures reliable operation of the SPEF protection of both current and directional principles including the changes of capacity abruptly networks caused by switching outgoing lines.

Prisons as total institution semiospheres

The main objective of this article is to combine Juri Lotman’s theory of the semiosphere – including its concepts of boundary, core, and periphery – with Erving Goffman’s theory of the total institution. The purpose is to develop a framework conducive to examining the prison as an object of study, equally emphasizing both its internal as well as external relations. This work positions itself within the contexts of the relative decline of the field of prison ethnography, few or no studies done applying semiotic metalanguage to the prison or the total institution, and none applying the theory of the semiosphere to either. This work is oriented according to an analytical or neutral mode; its point is not to offer a normative programme, but to offer a new description of the research object and a new language of description in which to speak of this object. The secondary objectives of this article include demonstrating that Lotman’s theory of the semiosphere and Goffman’s theory of the total institution are compatible, that Lotman’s theory actually refines Goffman’s original, that Lotman’s theory taken independently and Goffman’s theory as refined by Lotman’s are both compatible with the direction of contemporary prison ethnography, and that the framework presented in this work has the potential to reinvigorate the field of prison ethnography.

Rating of amplitudes of high harmonics in determining feeder with single-phase ground fault

The aim of the paper is theoretical and experimental research of processes during the single-phase ground faults in electrical distribution grids of 10/06/35 kV with isolated neutral mode. The mathematical method of rationing is used for the analysis of the spectral composition of currents and voltages increasing the information content of the allocated higher harmonics of current and voltage. The paper show a comparison of the results of spectral analysis with and without taking into account the mathematical rationing obtained on the simulation model. Field experiments have demonstrated the effectiveness of using of the method of mathematical rationing of the higher harmonic components of current and voltage for various types of single-phase ground faults. The results of field experiments provided an opportunity of improving the methodology of yearling detection of single-phase ground faults in electric grids of 6-10-35 kV with an isolated mode of neutral. The conclusion of the research is the possibility of a significantly more accurate selection of the resonant frequencies of the spectrum of currents and voltages obtained by using of the method of mathematical rationing. The possibility of earlier and more precise localization of the feeder with ground fault is shown on the base more precise selection of the resonant frequency currents and voltages.

Assessment of ferroresonance processes in schemes of 6-35 kV electrical grids on the basis of reliability analysis

The object of research is the choice of the optimal technical solution to prevent the development or the long existence of ferroresonance processes in electrical distribution grids of 6-35 kV, which are operated in isolated neutral mode. A lot of factors such as the grounding mode of a grid neutral, its capacitive current of a short circuit to the ground, the type and number of voltage transformers (VT) etc. influence on the probability of occurrence and duration of ferroresonance processes. According to the results of the research, the values of capacitive currents of a short circuit to the ground at which stable ferroresonance processes occur in electrical distribution grids of 6-35 kV are determined. The values of capacitive earth fault currents of a grid are decisive for the occurrence of a stable ferroresonance, but the nature of its flow is also influenced by additional accidental factors, such as: a grid voltage, an insulation status of power lines, a load of the secondary winding of voltage transformer etc. Therefore, a model for assessment the frequency of occurrence of a stable ferroresonance process in the electrical grid based on the analysis of the reliability of physical objects in the conditions of external actions was developed. In addition, an algorithm for determining the most dangerous scheme configurations of electrical grids concerning to a VT damage by the frequency of occurrence of a stable ferroresonance process in them and the choice of optimal solutions to prevent the VT damage were proposed.

Inviscid instability of a unidirectional flow sheared in two transverse directions

Linear inviscid stability of general unidirectional flows sheared in one transverse direction has long been investigated by numerous researchers using the Rayleigh equation. However, unlike the simple shear flow considered in this equation, most physically relevant unidirectional flows vary in two transverse directions. Here the inviscid instability of such flows is studied by the large-Reynolds-number limit asymptotic analysis. We derive an a priori necessary condition for the existence of a limiting neutral mode, and develop a new numerical method to accurately capture singular neutral modes.

Reexamination of the Wave Activity Envelope Convective Scheme in Theoretical Modeling of MJO

The skeleton model is one of the theoretical models for understanding the essence of the Madden–Julian oscillation (MJO). The heating parameterization scheme in the skeleton model assumes that precipitation tendency is in phase and proportional to the low-level moisture anomaly. The authors show that the observed MJO precipitation tendency is not in phase with the low-level moisture anomaly. The consequence of the wave activity envelope (WAE) scheme is reexamined by using a general MJO theoretical framework in which trio-interaction among convective heating, moisture, and wave–boundary layer (BL) dynamics are included and various simplified convective schemes can be accommodated. Without the BL dynamics, the general model framework can be reduced to the original skeleton model. The authors show that the original skeleton model yields a neutral mode that exhibits a “quadrupole” horizontal structure and a quadrature relationship between precipitation and low-level moisture; both are inconsistent with observations. With the BL dynamics and damping included, the model can produce a growing mode with improved horizontal structure and precipitation–moisture relationship, but deficiencies remain because of the WAE scheme. The authors further demonstrate that the general model with the simplified Betts–Miller scheme and BL dynamics can produce a realistic horizontal structure (coupled Kelvin–Rossby wave structure) and precipitation–moisture relationship (i.e., the BL moisture convergence leads precipitation, and column-integrated moisture coincides with precipitation).

Plasma! Notes on Bruno Latour’s Metaphysics of Law

Here, Laurent de Sutter poses a direct challenge to a principal tenet of Latour’s metaphysics: Latour’s commitment to empiricity, positivity and above all the trace by which alone an actor is grasped in actor-network theory. De Sutter embraces Latour’s argument about the ontological openness or generosity of law – it is the only mode, de Sutter reminds us, capable of seizing any being whatsoever and attaching it to an utterance or an action and thereby registering its agency and, importantly, rendering it compossible with beings of quite other pedigrees. As such, law is the only ‘ontologically neutral’ mode, but there is much more at stake than the harmonics of existential modes, namely the real composition of worlds and, indeed, of what must be defined as the unworldly: ‘all that exists only as non-existing’, ‘all that is present only as absent’, or again, ‘all that has form only as unformed’. These missing masses that Latour occasionally acknowledges, de Sutter argues, escape from the tendrils of the networks that define the real and the knowable, but enjoy something more than a mere negative or emptily theoretical existence. For Latour, plasma is simply the ‘dumping ground’ where he deposits the things that do not awaken his interest, a realm of obscurity that must be set off from the world of which clear and distinct representations are possible. To undo this surprisingly Cartesian tendency in Latour, perhaps, de Sutter suggests, it would be possible to recover plasma as the genus to which Deleuze’s dark precursor would belong. If there is identity, similitude, resemblance, traceability, in short the whole modern system of representation, it is only as a plasmatic excrescent. As a first step along this path, de Sutter makes a pitch for the recovery of what he calls the beings of sensitivity, which may affect other beings profoundly but which themselves leave no measurable trace.