Secondary Arc Current Research Articles

Study on the secondary current characteristics of transmission lines coupling arc dynamics model with Mayr resistance model

In high-voltage transmission lines, secondary arcs severely affect the stability of power systems. However, there has been no research to combine transmission line model with time-varying resistance secondary arc. In this study, the improved arc dynamics model, the Mayr resistance model, and the transmission line system were combined in the simulation model to investigate the influence of the compensation reactor, line length, and short-circuit fault location on the characteristics of secondary arc current. The results revealed that the inhibitory effect of shunt reactors was the best at the midpoint between the fault point and the end of transmission line. When the series reactance satisfied a certain value, the short-circuit current was considerably suppressed with only a slight increase in the secondary current. The lower resistance along the line and longer transmission lines accelerated the secondary arc extinction rapidly. The location of the short-circuit fault had a limited effect on secondary arc extinction. The arc extinction time fluctuated within a small range with the changes in the location of the short-circuit fault. The results of the study can provide a reference for suppressing secondary arc currents.

Determining optimal neutral reactor to limit overvoltages and duration of secondary arc of transmission lines

AbstractEven though shunt compensation of transmission lines (TLs) is a common practice to limit the overvoltages stemming from the Ferranti effect, it may cause transient and steady‐state resonant overvoltages when one phase is left open due to the single‐pole‐open condition following the temporary phase‐to‐ground (Ph‐g) fault. Furthermore, the existing shunt reactors potentially increase the duration of the secondary arc current at the fault point and hence prevent offering fast single‐pole reclosing. To exploit the mentioned issues, in recent studies, a neutral reactor is introduced, which is installed in the neutral point of the shunt reactors; nonetheless, obtaining the appropriate amount of it is remarkably challenging. In this paper, an optimal neutral reactor (ONR) is determined based on an optimization problem, which minimizes the neutral reactor cost subject to limiting both resonant overvoltages and the duration of the secondary arc current. In modelling, the Laplace domain is employed rather than the phasor domain to consider both transient and steady‐state conditions since this technique allows having better control over transient overvoltages as well as transient secondary arc.

Single-Pole Autoreclosure in uncompensated EHV AC mixed overhead-cable lines: A parametric time-domain analysis

The successful application of the Single-Pole Autoreclosure (SPAR) to Extra-High Voltage (EHV) overhead lines (OHLs), as well as to the overhead portion of EHV mixed cable-overhead lines (MLs), significantly improves system stability. SPAR success requires that the secondary arc self-extinguishes during the dead time: according to the literature, self-extinction times increase with the increase of both secondary arc current and recovery voltage. Steady-state analyses of EHV MLs not equipped with inductive shunt compensation showed larger secondary arc currents and smaller recovery voltages compared to OHLs. Since steady-state analyses cannot give indications on arc self-extinction times, transient studies are required to assess which of the above effects has a prevailing influence, i.e., whether SPAR in uncompensated MLs results hindered or facilitated. This paper presents a time-domain study of the SPAR cycle in an uncompensated 400 kV-50 Hz ML, making use of detailed ATP-EMTP line and fault arc models. A parametric study has been carried out, evaluating secondary arc current, extinction time and recovery voltage for different single-phase fault locations along the overhead section of the line. Transient simulation results point out to extinction times being shorter in MLs than in OHLs of the same total length.

Designing a Reactor for Use in High Voltage Power Systems and Performing Experimental and Simulation Analysis

Today, magnetically controlled shunt reactors are widely used in solving power quality problems. These reactors are designed to reduce system reactive power, control high super/special high voltage grid voltage, suppress power frequency, regulate overvoltage, eliminate generator excitation, dynamically compensate transmission line power charge, suppress secondary arc current, suppress system resonance. By using suitably designed silica plate core reactors at the input of the frequency converters in the electrical distribution system, the level of harmonic currents drawn from the electrical power distribution system can be reduced to certain rates. The core material, the air-gapped nature of the reactor core, and the sizing of the reactor have a great influence on the harmonic level of the current and its ability to reduce losses in the reactor. In this study, three reactors with different core materials and different air gap gaps are designed for a certain voltage value. Parametric analysis of the reactors designed to see the changes in inductance values depending on the load level has been made both theoretically and experimentally and using the Finite Element Method. As a result of the analysis, the inductance stability, losses and compliance of the reactors with the standards are presented. The reactor's magnetic circuit is modeled with ANSYS@Maxwell, realizing a solution based on this method. The magnetic circuit is simulated to see the behavior of the reactor. In addition, real-time verification of the designed alternating current reactor has been made. Optimum design was obtained by using different core materials and different core air-gaped tested experimentally. The effect of the air gap distance in the core on the magnetic field and inductance value was also obtained.

Experimental Study on the Extinction Characteristics of Secondary Arc Under Different Secondary Arc Currents Near Outdoor Insulator

On the transmission lines, the secondary arc is the arc that remains at the fault point after the short-circuit current is interrupted, which may pose a threat to the stable operation of the power system. In this article, the extinction characteristics of secondary arc near an outdoor insulator under different secondary arc currents are studied experimentally. The secondary arc has different extinction characteristics under different secondary arc currents of 10, 30, and 50 A. The arcing time, length, morphology, diameter, and breakdown voltage of secondary arc are discussed. Experimental results show that, with the increase in the secondary arc current, the arcing time also increases. The development of the secondary arc has stage characteristics. The length of the secondary arc increases steadily in the first stage and fluctuates greatly in the second stage. In addition, during the single discharge in the second stage, the morphology of the secondary arc will change significantly. The breakdown voltage of the upper electrode in the negative polarity is higher than that in the positive polarity, and it is found that this polarity effect is related to the motion of the secondary arc in space. The research results could provide some reference for investigating the physical characteristics and suppression measures of secondary arc.

Neutral Reactor Structures for Improved Single Phase Auto Reclosing in Multi-Circuit Multi-Voltage Transmission Lines

In this paper, novel neutral reactor structures are proposed to mitigate the secondary arc current (SAC) in non-conventional Multi-circuit Multi-voltage Transmission lines (MCMVTLs). The parameters of the reactors in the structure are optimized using the Non-dominated Sorting Genetic Algorithm II (NSGA-II). The optimization algorithm, coded in Python, regulates the multiple runs of an Electromagnetic Transients (EMT) simulation program to minimize the secondary arc current. The optimization trials are run in parallel on a 64 core computer to minimize the solution time. A detailed arc model was tested on the EMT program (PSCAD). Using this model and optimized parameters in the proposed neutral reactor schemes, the SAC is indeed extinguished in acceptable times. The SAC and TRV for neutral reactors with optimized parameters are up-to 68 and 77%, respectively, lower than the ones with parameters calculated by the conventional approach which ignores inter-circuit coupling. Meanwhile, the extinction times are up-to 46% faster. As a result, single-phase auto-reclosing in MCMVTLs is viable.

Analysis of transient recovery voltage and secondary arc current in transposed extra-high voltage lines in a two-phase auto-reclosing

Extra-high voltage (EHV) lines of 500–750 kV, providing transmission of electricity over long distances and at the same time performing the functions of intersystem communication at the level of the national power system, play an important role not only in normal modes, but also in emergency modes, ensuring the dynamic stability of the power system as a whole. In these lines, the overwhelming proportion of power cuts are caused by single-phase short circuits (90%), a significant part of which, being unstable arc faults, are successfully eliminated in the single-phase auto-reclosing cycle. Also, about 5%–10% of failures can be constituted by two-phase short circuits, which can be eliminated in a two-phase auto-reclosing cycle (TPhAR). The purpose of this paper is to study two-phase auto-reclosing in transposed EHV lines equipped with four-radial shunt reactors (ShR). The paper analyzes the efficiency of using a two-phase auto-reclosing to eliminate two-phase short-circuits in the lines connecting the power systems of Kyrgyzstan and Tajikistan. An algorithm is proposed for calculating the transient recovering voltages (TRV) and secondary arc currents (SAC) in the real transposed line Datka–Khujand–Dushanbe. The obtained results of TRV and SAC, which are within the permissible limits for the Dushanbe–Khujand line section, make it possible to have a dead time of TPhAR of no more than 0.6 s, in order to maintain the dynamic stability of the power system. For lines with a length of about 500 km (Datka–Khujand), equipped with three reactors, a successful TPhAR is impossible due to the appearance of resonant TRV in the circuit. The paper proposes the use of banks of capacitors connected in series in the phases of the ShR for the implementation of a successful TPhAR with the duration of the required pause of about 0.6 s.

Graphical Method for Calculating Secondary Arc Currents of an Arc in High-Voltage Lines

Graphical Method for Calculating Secondary Arc Currents of an Arc in High-Voltage Lines

Optimizing multi-circuit transmission lines for single-phase auto-reclosing

In this paper, novel multi-circuit transmission line (MCTL) designs with low secondary arc current (SAC) values are proposed. The Non-dominated Sorting Genetic Algorithm II (NSGA-II) was used to generate the optimized tower structures. The aim is to select the MCTL configuration that satisfies multiple objectives such as increased capacity, reduced cost, right-of-way (ROW), and tower height, while satisfying several constraints such as SAC limit, ampacity, electric field, etc. The objective function is formulated as a mathematical function of design variables such as sub-conductor position, phase arrangement, etc., and several constraints. Two-port theory is used to calculate the SAC resulting from different faults along the line, which is significantly faster compared with time-domain Electromagnetic Transient (EMT) simulations. Comparisons of MCTLs with and without SAC constraints are presented, clearly showing the importance of taking into account SAC limits during the optimization process. As a result, MCTL structures with SAC reductions of up-to 64% were obtained, indicating that the MCTL are able to successfully handle Single Phase Auto-Reclosing (SPAR).

Графический метод расчёта вторичных токов дуги в линиях сверхвысокого напряжения

The article discusses the issues of calculating secondary arc currents in the implementation of single-phase auto-reclosing for the elimination of unstable single-phase damages in ultra-high voltage lines of 500, 750 kV. The dependences of the extinguishing time of the feeding arc and the dead time of the single-phase auto-reclosing recommended in the literature on the amplitude of the forced component of the secondary arc current are given. A graphical method is proposed for calculating the secondary arc currents in ultra-high voltage lines in the dead time mode of the single-phase auto-reclosing. The adequacy of the simulation of the recharge arc is confirmed by comparing the calculated and experimental data as applied to the 750 kV line with a length of 525 km. Examples of using the graphical method for calculating the secondary currents of the recharge arc in 500 kV lines of various lengths are given. The features of the implementation of single-phase auto-reclosing in the line with a length of 300 and 1000 km and, in particular, the influence of zero-power reactors included in the neutral of shunt reactors are noted. An example of the implementation of single-phase auto-reclosing using automatic phase shunting in a 500 km line is also considered.

Study on the characteristics of secondary arc current of UHV high compensation degree TCSC line under the fine-tuning mode

Abstract In the transmission line, the series compensation device is often used to improve the transmission capacity. However, when the fixed series capacitor (FSC) is used in high compensation series compensation device, the stability margin cannot meet the requirements. Therefore, thyristor controlled series compensator (TCSC) is often installed in transmission lines to improve the transmission capacity of the line and the stability of the system. For cost considerations, the hybrid compensation mode of FSC and TCSC is often adopted. However, when a single-phase grounding fault occurs in a transmission line with increased series compensation degree, the unreasonable distribution of FSC and TCSC will lead to the excessive amplitude of secondary arc current, which is not conducive to rapid arc extinguishing. To solve this problem, this paper is based on 1000 kV Changzhi-Nanyang-Jingmen UHV series compensation transmission system, using PSCAD simulation program to established UHV series compensation simulation model, The variation law of secondary arc current and recovery voltage during operation in fine tuning mode after adding TCSC to UHV transmission line is analyzed, and the effect of increasing series compensation degree on secondary arc current and recovery voltage characteristics is studied. And analyze the secondary arc current and recovery voltage when using different FSC and TCSC series compensation degree schemes, and get the most reasonable series compensation configuration scheme. The results show that TCSC compensation is more beneficial to arc extinguishing under the same series compensation. Compared with several series compensation schemes, it is found that with the increase of the proportion of TCSC, the amplitude of secondary arc current and recovery voltage vary greatly. Considering various factors, the scheme that is more conducive to accelerating arc extinguishing is chosen.

Influence of Series Compensation Degrees on Secondary Arc Current Characteristics under the Different Series Compensation Mode

AbstractThe high compensation degree series compensation has a broad development prospects in long distance and large-capacity UHV transmission lines. But it is generating secondary arc current contains low frequency components with high amplitude when the single-phase grounding fault occurs in the series compensated transmission line, which is not conducive to rapid arc extinguishing. To solve this problem, this paper based on the mechanism of generating secondary arc by series compensation transmission lines, and using ATP – EMTP electromagnetic transient program to establish the simulation model of UHV series compensation device. And the suppression effects of small resistance short connection fault series compensation and linkage bypass series compensation measures on secondary arc current and recovery voltage under different series compensation layout mode are studied respectively. The results show that the attenuation speed of the secondary arc current is related to the series compensation arrangement modes and the time when the series compensation device is short connected or bypassed. Series compensation device short connected or bypassed before circuit breaker tripping which can accelerate the arc extinction speed, and the suppression effect is better when the series compensated double platform segmentation layout is distributed on both sides of the line. The results can be used as a reference for the engineering design of UHV with large capacity and long distance and high compensation series compensation transmission lines.

Characteristics of Secondary Arc Current on UHV DC and EHV AC Transmission Lines Erected on the Same Tower

Abstract With the continuous expansion of the scale of power system, corridor resources of overhead transmission lines tend to be saturated in China, making AC/DC erection on the same tower a trend in future development. The AC/DC coupling effect will cause DC line to generate secondary arc current at the point of failure when transmission line fails, which affects the DC restart. On account of the mechanism of generating secondary arc current by AC/DC lines erected on the same tower, this paper uses PSCAD to establish simulation model for AC/DC erected on the same tower. And the effects of different fault locations, lengths of coupling sections, and different transposition modes of AC lines on the secondary arc current and recovery voltage of AC and DC lines are studied. The results show that secondary arc current on DC line is greatly affected by fault location and length of coupling line, and using different transposition modes of AC lines can reduce secondary arc current on the DC lines effectively. According to Yunguang UHV DC restart time sequence, setting the restart time sequence can increase the first restart deionization time to ensure the stable operation of the system.

Electromagnetic Transient Analysis of 500 kV XLPE Submarine Cable Interconnection Project from Zhenhai to Zhoushan

In Zhenhai-Zhoushan transmission project, 500kV XLPE submarine cable lines are used for the first time in the world. Using electromagnetic transient simulation program(EMTP), electromagnetic transient problems in this project are investigated including electrical parameter of submarine cable lines, power frequency overvoltages, secondary-arc currents and recovery voltages during the single-phase reclosing, power frequency resonance overvoltages, induced voltages and induced currents, switching surges and so on. On the basis, the recommended configuration scheme of HV shunt reactors and neutral reactors is proposed. In addition, it is suggested to install closing resistors of 400ohm on both sides of line breakers in order to restrict switching overvoltages and ensure safe operation of submarine cable lines.

Influences of secondary arc-based grading capacitor of multi-break circuit breaker on the transient stability of power system

The grading capacitor (GC) of circuit breaker (CB) is one of the most cost-effective methods to suppress secondary arc. Taking the double-break CB as an example, its topology is briefly introduced. The electric circuit for power system with GC is then established. From the perspective of minimizing secondary arc current, the formula for the capacitance of GC is deduced according to the Kirchhoff's voltage law. Based on the equal-area criterion, the transient process of power angle and speed of generator in the event of fault is investigated, and the role of GC in the transient stability is quantitatively investigated. Meanwhile, the expressions for the accelerating and decelerating areas are computed through the numerical calculus, and the impact of GC capacitance on the critical clearing time (CCT) is discussed. Furthermore, to verify the aforementioned analysis, a model is established in the environment of MATLAB/Simulink, and two cases are considered, i.e., a single machine infinite bus (SMIB) power system and a multi-machine power system. Both the theoretical analysis and the simulation results demonstrate that the use of GC can strength the electrical connection between two remote power sources, undermines the oscillating amplitude of power angle, and shorten the attenuation duration. As a result, the CCT and transient margin would be increased. In other words, we can prong the dead time and guarantee the successfulness for autoreclosure scheme. The GC of CB is much superior to the existing four-legged shunt reactor and high speed grounding switch in addressing the secondary arc issue.

Investigation on volt-ampere characteristic of secondary arc burning in atmospheric air

The secondary arc, as a common phenomenon in a high voltage power transmission system, is an essence of an electric arc. It not only damages the electrical power equipment but also threatens the safety of the power system. A series of experiments on the secondary arc have been conducted in this work. The volt-ampere curves are measured, the motion trajectories are captured, and the centroid of the secondary arc body is calculated by means of image processing. The experimental results indicate that the secondary arc length can reach several meters, and its volt-ampere curve is completely different from that of short-gap arcs and others operated in some special dielectrics such as vacuum. The evolution of the secondary arc can be generally divided into two stages. In the early stage, the arc column performs a vertical motion and has an upward trend due to thermal buoyancy. Basically, the volt-ampere curve has a shape of a regular hysteresis loop. The impacts of the frequent short-circuit behavior of the arc column on the volt-ampere curve and arcing time are investigated. At the later stage, the secondary arc temperature drops and the zero-off behavior becomes obvious. The volt-ampere curve is inevitably affected. The zero-off duration is obtained, and the key factors are discussed. The dynamics of charged particles in the zero-off interval are analyzed. Furthermore, under the effect of strong wind, it has been found that the secondary arc current is occasionally forced to zero and preceded by the voltage. The mechanism for such a phenomenon is first elucidated from the perspective of energy balance. The results lay a theoretical basis for secondary arc physics.

Secondary Arc Current During DC Auto Reclosing in Multisectional AC/DC Hybrid Lines

In this paper, a contribution to the analysis of electromagnetic ac to dc interactions in complex ac/dc hybrid overhead lines was made. For accurate calculation of such coupling, standard transformations like the symmetrical components cannot be used. Therefore, a method based on adjusted modal decomposition was presented, which allows analysis of untransposed and partly transposed configurations in arbitrary switching states. The method was applied to the case of dc fault clearing using single-pole auto reclosing (dc SPAR), where parallel ac circuits could induce a secondary arc in the dc line. The magnitude of the secondary arc current was examined, which allows evaluating the necessary dead time of the dc SPAR. The influence of parameters like line configuration, load flow, and fault location was discussed. After that, a realistic study case hybrid line was analyzed. In particular, the comparison to secondary arcs in ac lines and the behavior as a function of fault location in the context of changing ac systems and line configurations along the hybrid dc corridor provide new insights into a relevant phenomenon.

Influence of Hybrid Reactive Power Compensation on the Secondary Arc of Ultra-High-Voltage Transmission Lines (May 2018)

Hybrid reactive power compensation (HRPC) which consists of series compensation and a stepped-controlled shunt reactor will see use in China's future ultra-high-voltage (UHV) transmission system. As a result, some new characteristics of the secondary arc during a single-phase-to-ground fault on UHV transmission lines with HRPC may be raised. In this paper, the secondary arc characteristics during the single-phase auto-reclosure (SPAR) operation have been simulated with regard to the UHV AC system installed with HRPC. Based on the UHV system model with HRPC and its secondary arc model, the influence mechanism of HRPC on secondary arc current is theoretically derived with the simulated waveforms and the Fourier analysis. Besides, the relationship among the secondary arc current, the arcing time with different HRPC compensation degrees, neutral reactance, as well as the grounding fault locations have been investigated in detail. Finally, an improved time sequential control strategy of bypass breaker and SPAR has been put forward. The research presented in this paper will provide necessary theoretical basis and technical support for the future application of HRPC in UHV transmission lines.

A Study on the Transient of Secondary Arc Current of UHV Transmission Lines

Secondary arcs are a type of alternating-current electric arc burning in open space, the arcing times of which are closely related to the transient of their currents. To elucidate the formation mechanism of the transient, the secondary current was first decomposed into the natural component and the forced component. Then, the corresponding circuit models were established and the formulas calculating these two components were derived. By means of the electromagnetic transients program simulation, the typical secondary arc current waveform is gotten, and its evolution is divided into three stages based on its characteristics. The influences of key factors (e.g., secondary arc resistance, shunt compensation degree, and neutral reactor) on the transient were investigated, and the most critical factor was obtained. It indicates that the transient of secondary arc current is mainly characterized by its natural component. Furthermore, using the Laplace transform method, and along with the simplification of the system circuit, the characteristic equation for the UHV transmission line was developed, and the damping factors and resonant frequencies of the natural component were solved. Compared with the previous steady-state analysis, the relationship between the decaying and oscillating processes with the system parameters is quantitatively explained. Rather than the line length, the neutral reactor, the decay of secondary arc current is directly proportional to the arc resistance, but inversely proportional to shunt reactor. The proposed methodology can be also applied to recovery voltage study. The results are essential for the transient analysis, the choice of neutral reactor, as well as the implementation of single-phase auto-reclosing strategy.

Effect of duration of the pause single-phase auto-reclosing on electro-power transmission capacitance

This paper discusses the problem associated with accidents in the aerial line (AL) ultra-high voltage (UHV) due to its big length. In lines with a voltage of 500-1150 kV the overwhelming proportion of trips (98%) is caused by single-phase short circuit (SPSC). A substantial portion (70%) single-phase short circuits is erratic arc accidents which can be successfully eliminated in a high-speed auto-reclosing (HSAR) or single-phase auto-reclosing (SPAR). Success single-phase auto-reclosing (SPAR) at liquidation by single-phase short circuit (SPSC), on the one hand, is determined by the characteristics of the secondary arc current, and on the other hand the effectiveness of ways to reduce secondary arc current and recovery voltage development. The minimum dead time, at a HSAR it is usually taken as 0.5 s., at single-phase autoreclosing (SPAR) it depends on the current value of the arc support is in the range of 0.5-3.0 s. The article shows high efficiency of use single-phase auto reclosing (SPAR) at liquidation SPSC in a single-chain AL voltage of 500 kV, the dependence of the bandwidth of transmission in maintaining the dynamic stability from the length of the pause SPAR.