Secondary Arc Research Articles

An optimal procedure for solving the hierarchical network design problem

The hierarchical network design problem consists of finding a minimum cost bilevel network that connects all the nodes in a set, created by a loopless main path and a forest. The main path is formed by primary (higher cost) arcs, providing a path between an origin node and a destination node. The forest, built using secondary (lower cost) arcs, connects all the nodes not on the main path, to the path itself. We state and prove some properties of the problem, which allow finding good upper bounds to the solution in polynomial time when the primary costs are proportional to secondary costs. We also propose an O(n 4) procedure to improve on these bounds. In turn, these bounds are used to significantly reduce the number of nodes and arcs of the problem. Once the problem is reduced, large instances can be solved to optimality. At this stage, we use one of two linear integer optimization formulations. The first and preferred one is based on multicommodity flows, which avoids the formation of subtours. The second formulation avoids subtours by iteratively adding ad hoc constraints. We show some examples and provide computational experiments performed on networks with sizes up to 600 nodes and 14 000 arcs.

A Plasma Railgun Experiment Addressing Launch-to-Space Issues

The Institute for Advanced Technology has recently been awarded a grant by the U.S. Air Force Office of Scientific Research to undertake research in the area of hypervelocity, plasma-driven electromagnetic launch. This paper describes our technical approach to achieving 7 km/s at accelerations that are lower than typical for plasma launchers. Our approach to managing plasma restrike and secondary arc formation is to reduce the emission of ablated materials into the gun bore through the use of augmentation and ceramic sidewalls. In addition, preinjection to 1 km/s is used to provide an initial velocity for the launch package while introducing minimal dense cold gas, since such gas can also contribute to restrike. This paper describes the hardware that is being put in place for this experiment

New Digital Algorithm for Adaptive Reclosing Based on the Calculation of the Faulted Phase Voltage Total Harmonic Distortion Factor

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper presents a new numerical algorithm suitable for determining adaptive dead time, and blocking automatic reclosing during permanent faults on overhead lines. It is based on terminal voltage input data processing. The decision if it is safe or not to reclose is determined by the voltage signal of faulted and tripped line phase using the total harmonic distortion factor calculated by discrete Fourier transform. The algorithm was successfully tested using signals recorded on the real power system. The tests demonstrate the ability of the presented algorithm to determine the secondary arc extinction time and to block unsuccessful automatic reclosing of high-voltage lines with permanent fault. </para>

Simple Optimizing Method of Shunt Reactor Connected to Double Circuit UHV Transmission Line for Minimizing Maximum Secondary Arc Current

Simple Optimizing Method of Shunt Reactor Connected to Double Circuit UHV Transmission Line for Minimizing Maximum Secondary Arc Current

The Adequacy Analysis for Installation of High Speed Grounding Switches on the Korean 765kV Single Transmission Line

This paper analyzes arc phenomena including the secondary arc's elongation in the Korean 765kV single transmission line (79km) between Sin-Ansung S/S and Sin-Gapyeong S/S, which will be installed in Korea in June 2006. In particular, both frequency independent and frequency dependent line models are compared to make our final decisions. As well, the significant simulation results are investigated by the EMTP program. As a result, there is no need of HSGS in the Korean 765kV single transmission line from both a practical and an economical point of view.

Proposal of a Current Regulative Diode for Power Supply in Sustained Arc Test

A power supply for electrostatic discharge (ESD) test on solar arrays, which adopts a current regulative diode (CRD), was proposed. The CRD can cause the flow of a constant current in spite of the applied voltage and can also reduce the surge current due to a large internal capacitance in the power supplies. The performance of the CRD power supply was measured on short-circuit conditions and was also tested for ESD tests. The CRD circuit showed good performance and could cause the sustained arc as well as the secondary arc. It was confirmed that the CRD power supply was useful for ESD ground tests

A Novel Adaptive Single-Phase Reclosure Scheme Using Dual-Window Transient Energy Ratio and Mathematical Morphology

It is well known that most adaptive autoreclosure schemes are dependent on the voltages sampled from the transmission lines to distinguish between the transient faults and the permanent faults; therefore, the transforming characteristics or required mounting position of the voltage transducer will limit the applications of voltage-based schemes. To overcome this disadvantage, a criterion of a dual-window transient energy ratio (ER) based on mode current to implement the adaptive autoreclosure of transmission lines is proposed in this paper. It is demonstrated that the ER approaches 1 during the steady-state where it increases greatly during some moments; for instance, for the fault occurrence, breaker opening and closing, the existences of primary and secondary arcs, and arc extinguishing. Therefore, the setting of the criterion is easy. To effectively extract the high-frequency energy of the mode current, a novel concept of generalized multiresolution morphological gradient (GMMG) is put forward on the basis of the multiresolution morphological gradient (MMG). The design of GMMG is more flexible and the relative factors of the structure element can be regulated according to the desirable effects. Electromagnetic Transients Program-based simulation results show that the GMMG-based autoreclosure scheme improves the reliability of fault discrimination and promises to be applied to the real power systems

Electrostatic Discharge Ground Test of a Polar Orbit Satellite Solar Panel

The Advanced Land Observing Satellite that was launched by the Japan Aerospace Exploration Agency in 2006 carries a large solar-array paddle of 22 times 3 m in polar orbit. The wake side of the solar paddle can be charged to a negative value exceeding -1000 V. Numerical simulations and laboratory experiments are carried out to investigate charging and arcing phenomena on the backside of the solar paddle that has exposed bypass diode boards and silver-Teflon thermal film. Possibility of secondary arc and surge voltage between hot and return ends of power circuit has been investigated. The authors irradiate solar-panel coupons with an electron beam to simulate charging situation near the North Pole. Surface flashover is observed once the insulator potential exceeds -7000 V. The authors have also tested charging situation near the South Pole where carbon fiber-reinforced plastics surface facing dense ionospheric plasma may arc easily once a satellite potential drops to -80 or -90 V. The solar-paddle design has been modified to increase the safety margin against arcing, and tests have been carried out to identify the strength limit under extremely harsh test environment

An adaptive single pole autoreclosure based on zero sequence power

In this paper, a novel adaptive single pole autoreclosure is introduced. This reclosure is based on monitoring the fundamental component of the zero sequence instantaneous power to detect the extinction instant of the arc in its secondary period. Thus, adaptive closing instant can be achieved. The concept of reclosure is validated via typical examples of transmission line exposed to ground arcing fault. Effects of fault location and load flow on the accuracy of the technique are examined. Discriminatory zones of the secondary arc period in the zero sequence power domains are determined. A proposed threshold for the reclosing instant is introduced and examined. Validation of the proposed algorithm is verified via Digital Signal Processing (DSP) experimental test set-up. The test results corroborate the efficacy of proposed technique.

Numerical Algorithm for Adaptive Single Pole Autoreclosure Based on Determining the Secondary Arc Extinction Time

This article presents a new numerical algorithm suitable for defining recloser reclaim time and blocking automatic reclosing during permanent faults on overhead lines. It is based on terminal voltage input data processing. The decision if it is safe or not to reclose is determined from the voltage signal of faulted and tripped line phase using fundamental and third harmonic calculated by discrete Fourier transform. The algorithm was successfully tested using signals recorded on the real power system. The tests demonstrate the ability of presented algorithm to determine the secondary arc extinction time and to block unsuccessful automatic reclosing of HV lines with permanent fault.

Arc characteristics and a single-pole auto-reclosure scheme for Alexandria HV transmission system

Arcing faults are the most common faults that occur in the 220 kV transmission line national grid of Egypt, in the vicinity of ‘Alexandria’ city. This part of the network also feeds a large industrial load in the form of steel works, which injects a large amount of harmonics into the network. In this paper, the performance of this 220 kV TL network during arcing faults is studied with the aid of the PSCAD/EMTDC program together with a specially designed arcing fault custom model incorporated in the program. Several arcing faults are simulated, and the effect of harmonics on the fault current and secondary arc duration time is demonstrated. Based upon the simulation results, recommendations regarding single-pole autoreclosing and arc suppression methods are suggested.

Modeling of Secondary Arc on High Voltage Solar Array in Space

Secondary arc on solar array in space is defined as an arc discharge short-circuiting adjacent solar cells. As operational voltage of spacecraft increases to 100V, there is more risk of secondary arc that can destroy solar array circuit. Secondary arc is categorized as vacuum arc, although its current is very low, even less than 1A. One-dimensional modeling is carried out to derive sets of parameters that satisfy the governing equations. Genetic Algorithm is used to find the optimal set of solutions. Even at a current less than 1A, the solutions exist though the arc voltage is higher than the experimental values by several ten volts.

The Effect of Ground Resistance on Secondary Arc Current on an EHV Transmission Line

After a single-phase-to-ground fault occurs on an extremely-high-voltage transmission line, the duration of the secondary arc mainly depends on the magnitude of the secondary, which is determined by the ground resistance and the system's equivalent impedance at the fault location. In this paper, analytical formulas for calculating the system's equivalent impedance have been developed for three different arc-extinguishing techniques. These formulas show a satisfactory accuracy in comparison with electromagnetic transient program (EMTP) simulations. Then, the effect of the ground resistance on the secondary arc current has been evaluated by comparing it with the system's equivalent impedance. The resistance hardly influences the secondary arc current when no arc-extinguishing facility is adopted or when four-reactor banks are employed; while the resistance significantly affects the current when high-speed grounding switches are used.

低地球軌道プラズマ環境下での二次アーク発生条件

Arcing on satellite solar array due to interaction with space plasma may cause permanent loss of satellite power, once the arc becomes permanent sustained arc. An arc on solar array becomes a secondary arc when solar array circuit is short-circuited and provides energy to the arc plasma. The permanent sustained arc, the final stage of the secondary arc, destroys a solar array string or the complete power circuits at the worst case. To investigate the threshold conditions for the secondary arc formation, laboratory tests are carried out in a xenon plasma chamber simulating LEO plasma environment with an external circuit simulating a spacecraft power system. Solar array coupon panels simulating the hot and return ends of a string circuit are tested for various combinations of string voltage and string current. Experimental results show that formation of secondary arc strongly depends on the string voltage and duration of secondary arc depends on the string current.

Detecting secondary arc extinction time by analyzing low frequency components of faulted phase voltage or sound phase current waveforms

This paper suggests a new adaptive single-pole auto-reclosing technique based on tracking a single harmonic distortion index (HDI) that represents the behavior of the low frequency components of the faulted phase voltage or sound phase current waveforms and a decision-making index that is defined based on properties of the tracked HDI. The advantage of this technique is that the threshold values, set for indices, can be chosen almost independent of pre-fault loading conditions and line parameters.

Transmission System Parameters Optimization— Sensitivity Analysis of Secondary Arc Current and Recovery Voltage

This paper shows the importance of optimizing the transmission system parameters from its conception, considering the relevant options and possibilities, in order to have a better cost-performance result. The presented results were obtained in the study of a real transmission system expansion, based on a 865-km long line. The single-phase auto-reclosing (SPAR) procedure was one of the aspects carefully studied, in order to assure adequate transmission reliability. The secondary arc current was mitigated through the traditional solution of using the neutral reactor on the existing shunt reactor banks, which permitted the reduction of the secondary arc current to acceptable values, assuring natural arc extinction and successful SPAR. The method of obtaining the optimized value for the neutral reactor and its implications on the system performance are important aspects, and are discussed in this paper.

A Probabilistic Approach for Secondary Arc Risk Assessment

A probabilistic methodology for secondary arc extinction time calculations is presented. The proposed approach permits the calculation of the probability of secondary arc extinction as a function of time and represents an extension of the well-known deterministic model proposed in , where the extinction time is obtained from EMTP-type simulations and groups of secondary arc reignition voltage curves. Instead of using only one pessimistic characteristic, a probability distribution is evaluated to randomly select the reignition voltage curve to use for each calculation. As opposed to the deterministic methods, the proposed probabilistic approach allows the assessment of the risk undertaken by a power system under different single-pole reclosing time schemes and distinct weather conditions alike.

Arc Effect on Single-Phase Reclosing Time of a UHV Power Transmission Line

One of the important operational conditions of a single-circuit ultra-high-voltage transmission line is the power transmission by two phases during the clearance of a temporary single-phase short circuit. Such a condition may be sustained for an interval of 1 s without losing the dynamic stability of the system. The influence of the arc on the single-phase reclosing time of an ultra-high-voltage power transmission line is investigated on the basis of the primary and the secondary arc models incorporated into the transient program EMTP. The validity of the models used is proven by comparison with field test results on an actual 1150-kV power transmission line from Ekibastuz to Kokchetav in Northern Kazakhstan. The processes of this power transmission in the "dead time" of the single-phase reclosing cycle are simulated. It is shown in the paper that simplified short-circuit simulation without the incorporation of the dynamic arc model leads to erroneous results. Mathematical analysis and field experiments show that natural secondary arc extinguishing in a highly compensated 1150-kV power transmission line cannot be reached in a reasonable time (e.g., less than 1 s). It is shown in the paper that this problem can be solved by automatic phase shunting (APS) of the faulted phase.

Modeling secondary arc based on identification of arc parameters from staged fault test records

A realistic representation of the secondary arcs is essential in determining the auto-reclosure performance of EHV transmission lines. In this paper the dynamic behavior of the arc is presented as a time-varying resistance using the MODELS feature of the ATP–EMTP program. It is shown that random variation of the arc parameters influences significantly the arc extinction time besides the capacitive and inductive coupling between the faulty and the sound phases. Parameters for the arc model have been extracted from staged fault tests records carried out on a double-circuit, uncompensated 400 kV interconnecting line. The results of the simulation proved the importance of the distributed nature of the transmission line and the nonlinear characteristic of the arc resistance in the intermittent region of arcing. The arc current is determined by wave processes in this interval. As a result, the continuous current characterizing the first period of secondary arcing is followed by individual current impulses of much higher amplitude. The high energy re-ignitions of the second period may push back the arcing process into the continuous condition, which multiplies the self-extinction time.

Precipitation and nonlinear effects in geomagnetic field line resonances

The structure of auroral arcs sustained by field line resonances (FLRs) is determined using a model that describes the interplay between ionospheric feedback, nonlinear, and dispersive effects in a curvilinear geomagnetic topology. The model includes modulation of Pedersen conductance by hundreds of eV electrons that precipitate in the ionosphere through the action of shear Alfvén wave field‐aligned currents (FACs). The competition between ionospheric feedback dissipation, wave dispersion, and nonlinearity results in large‐amplitude, long‐period oscillations of the FAC, and in emission of slow‐moving small‐scale secondary auroral arcs and density perturbations. Using observed values of nightside conductivities and realistic topology of geomagnetic field lines, we obtain FLRs with frequencies in the range of a few mHz, spatial scales up to several km near the ionosphere, and FAC amplitudes extending to tens of μA/m2. Our model explains the excitation of structured auroral arcs in regions of low ionospheric conductance.