Arc Extinction Time Research Articles

Theoretical and experimental studies on the self‐healing properties of metallised capacitor films under multiple stresses

AbstractMetallised film capacitors, for the most important merits is the excellent self‐healing property, have significant electrical insulation advantage. The essential factors affecting the self‐healing properties of metallised polypropylene film capacitors (MPPFCs) are first analysed, and a self‐healing performance characterisation test platform for metallised polypropylene capacitor films was built. Both the voltage/current waveforms and discharge patterns of the self‐healing process under multiple stresses including temperature, voltage and inter‐layer pressure were recorded and discussed. The correlation between self‐healing performance characterisation and the carbon that appeared on the surface of the dielectric layer during the arc extinction time is clarified. Finally, by virtue of an equivalent dynamic circuit model, the influence of square resistance and the equivalent capacitance of the power grid on self‐healing has been theoretically studied.

Analysis and mitigation techniques of overvoltages due to insulator transient arcs clearing on a 500 kV OHTL

In high-voltage OHTL, Overvoltages and arc currents due to insulator transient arcs clearing severely affect the stability of power systems.In this paper, a 500 kV Egyptian OHTL was simulated using ATP-EMTP software package. The insulators transient arcs clearing of the system were tested under different impedances of tower footing, locations of insulator arc tower, angles at which the arc initiate. Additionally, the effects of the corona phenomenon were taken into account to achieve realistic study. Furthermore, these factors thoroughly were analyzed to determine worst-case scenarios. Also the paper evaluated the performance of the overvoltage mitigation methods based on the installation of neutral shunt reactors, MOSA (Metal Oxide Surge Arresters), or combinations of both.The results demonstrated that the combination of MOSA and neutral shunt reactors was the most effective mitigation technique, reducing overvoltages by approximately 57.4 %, arc currents by 80 %, and arc extinction time by 27.3 %Notably, the most severe overvoltages and peak arc currents occurred at an angle of θ = 180° and footing impedance 30Ω. Additionally, the corona phenomenon played a role in reducing the severity of overvoltages, arc currents, and arc extinction time by approximately 56 %, 56 %, and 1.8 %, respectively. Finally, These findings provide valuable recommendations for mitigating overvoltages, arc currents, and arc extinction time during insulator arc clearing events.

Adaptive single-phase auto-reclosing scheme based on the moving average filter-quadrature signal generator for transmission lines with shunt reactors

An adaptive single-phase auto-reclosing method based on the moving average filter (MAF)-quadrature signal generator (QSG) is developed to determine secondary arc extinction time for high-voltage transmission lines with shunt reactors. Firstly, the difference between permanent and transient faults is derived and analyzed by the equivalent circuit model. Then, MAF-QSG is utilized to extract these features from the fault voltage. During the second arc period, for transient fault, the fundamental component and subharmonic component with around 50 Hz are reserved by MAF-QSG; however, in the case of permanent fault, only the fundamental component is retained. Finally, the identification index and its threshold are designed above the extraction fault features. The performance of the proposed method is evaluated by simulation and field data studies, accounting for different transmission line compensation levels, transition resistances, and fault location conditions.

A Method for Judging the Arc-Extinction Time of Resonant Grounding System Based on Frequence Difference

In the resonant grounding system, the accurate judgment of arc-extinction time has guiding significance for the line selection of grounding fault, the evaluation of the arc suppression effect, and the extraction and utilization of transient information after arc extinction. Aiming at the single-phase grounding fault of resonant grounding system, this paper analyzes the frequence change characteristics before and after arc extinction. It is found that the frequence of zero-sequence electrical quantity before arc extinction is power frequence, and it changes after arc extinction. It is used to construct single-frequence methods and dual-frequence methods for judging arc-extinction time. As a tool for dynamic frequence measurement, SOGI-FLL is utilized to realize the engineering application of the method for judging arc-extinction time. The method’s accuracy is proved by Matlab/Simulink simulation and field test.

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.

Influence of the Secondary Arc on the Operation of Single Phase Autoreclosure of the 400 kV interconnection between Hungary and Croatia


 
 Sažetak: Faults on EHV lines are generally single-phase-to-ground ones and not permanent in the majority of cases. Thus single phase auto reclosure (SPAR), at which the faulty phases are tripped for a short time, eliminates the predominant part of the faults [1,2]. The secondary arc, which follows the high power arc after tripping the faulty phases at both side of the line may endanger the successfulness of reclosing if the duration of the switched off interval (dead time) is not long enough to ensure the extinction of the arc. The secondary arcing times recorded on different EHV lines or measured in laboratory tests show significant spread, consequently, to select a dead time according to the longest experimental secondary arc extinction time is not feasible. During commissioning of the double circuit 420 kV interconnection between Hungary and Croatia several staged faults were initiated to analyze the arc extinction performance. Initially the line was in operation by connecting the two circuits in parallel along the 1/3rd of the full length. In this configuration the longest secondary arc extinction time was 4 seconds and the secondary arc has not extinguished in 27s in one of the tests, so the line had to be tripped out to clear the staged fault. Later on, the length of the Croatian section of the line has been significantly shortened after putting a new substation into service. The increased performance of SPAR of the new arrangement has been proved with field tests. A realistic representation of the secondary arcs is essential in determining the auto-reclosure performance of EHV transmission lines. As shown in the paper, the random variation of the arc parameters influences significantly the arc extinction time. The results of the field tests confirmed the importance of the distributed nature of the transmission line and the nonlinear characteristic of the arc resistance in the intermittent region of arcing, where temporary extinctions and sudden re-ignitions in the arc channel produce transient wave processes along the line.

Terminal voltage correlation-based adaptive reclosure strategy for VSC-MTDC grids

Auto-reclosure in VSC-MTDC grids has the defect of blindly reclosing. Research on adaptive reclosure strategies capable of identifying fault property and arc extinction time is essential to promote the reliability of power supply. This paper proposes a novel adaptive reclosure strategy for VSC-MTDC grids. At first, the terminal voltage is derivated by Marti model, which takes the distributed and frequency-dependent characteristics of the line parameters into account. The calculation result of the terminal voltage achieves high accuracy. Subsequently, a main criterion exploiting Pearson correlation coefficient between the calculated terminal voltage and the actual terminal voltage on the faulty line is proposed for identifying the fault property and the arc extinction time. Moreover, an auxiliary criterion utilizing the steady-state amplitude of the terminal voltage is added to further ensure the identification reliability of fault property. Finally, the effectiveness of the adaptive reclosure strategy is verified in PSCAD/EMTDC. The influencing factors and advantages of the proposed strategy are discussed and compared.

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.

A deep long Short-Term memory based scheme for Auto-Reclosing of power transmission lines

The operating speed of adaptive single-phase auto-reclosure (ASPAR) is of great importance to maintain power systems stability in high-voltage power transmission lines (PTLs). This paper proposes a two-step protection scheme using the long short-term memory (LSTM) network to enhance the ASPAR performance. The discrimination between transient and permanent faults is made by an LSTM with high accuracy in the first step. If transient faults are detected in the second step, another LSTM is applied to predict the secondary arc extinction time (SAET). To this end, the second LSTM accurately foresees the voltage waveform of the faulty phase a half-power cycle earlier, and predicts the SAET in order to get a successful reclosing. The results obtained from extensive simulations using EMTP-RV and MATLAB software environments indicate that the presented protection scheme outperforms other ones in terms of fault type classification, achieving an F-measure value of 98.90%. Moreover, the results verify that the LSTM can accurately estimate the voltage waveform and the SAET, that ensures a successful reclosing of the faulty phase.

Voltage integral ratio based adaptive reclosing scheme for true bipolar flexible HVDC system

Adaptive reclosing capable of identifying fault properties and arc extinction time can make up for the blindness defects of traditional auto-reclosing. Research on adaptive reclosing is necessary to quickly restore power supply and improve power system stability. At first, fault characteristics are divided into different fault stages. The characteristics of faulty pole voltage under different fault stages are derived. Then, an integral ratio algorithm is used to extract the characteristic differences of faulty pole voltage. After the transient fault arc is extinguished, the integral ratio will always exceed threshold within a cycle judgment time. Finally, different arc extinction times are simulated by the arc model. An adaptive reclosing scheme for true bipolar flexible high voltage direct current (HVDC) systems is proposed. The scheme can withstand the influence of arc combustion time, fault location, transition resistance, and noise. The performance of the proposed scheme has been verified via the simulation results obtained from PSCAD/EMTDC.

Study on the Influence of Injected Lightning Current on the Space-Time Evolution of Secondary Arc

The timely extinction of secondary arc is of great significance to the single-phase reclosing of transmission lines. However, very little research has been carried on the space-time evolution of secondary arc under lightning strikes. In this article, considering the electromagnetic force, thermal buoyant force, wind load and air resistance in the motion of secondary arc, a chain arc model was established, which was combined with the double exponential function injected lightning current model. The motion of secondary arc and the change of arc extinction time with or without injected lightning current were observed. The results show that lightning could accelerate the motion of secondary arc and shorten the extinction time of secondary arc. Then, by adjusting the different parameters of injected lightning current function, lightning start time, and lightning duration, the impact of various factors on the motion process of secondary arc and extinction time was obtained. Different wind loads and secondary currents were selected to observe the impact of the same injected lightning current with different secondary current and arc movement environment. The results show that a higher injected lightning current level and a lower secondary current could both make the impact of the injected lightning current more obvious. The lightning duration and lightning start time would not have a significant impact on the extinction of secondary arc. Lightning can reduce the difference between secondary arcs under different winds, and further promote the extinction of secondary arcs. The abovementioned research work can provide some reference for the protection of secondary arc in thunderstorm field.

Adaptive Single-Pole Auto-Reclosing Scheme Based on Secondary Arc Voltage Harmonic Signatures

This paper presents an advanced adaptive single-pole auto-reclosing (ASPAR) scheme based on harmonic characteristics of the secondary arc voltage. For analysis of the harmonics, short-time Fourier transform (STFT), which is a universal signal processing tool for transforming a signal from the time domain to the frequency domain, is utilized. STFT is applied to extract the abnormal harmonic signature from the voltage waveform of a faulted phase when a transient or permanent fault occurs on a power transmission line. The proposed scheme uses the total harmonic distortion (THD) factor to determine the fault type based on the variation and distortion characteristics of the harmonics. Harmonic components in the order of odd/even are also utilized to detect the secondary arc extinction time and guide the reclosing operation. Based on these factors, two coordinated algorithms are proposed to reduce the unnecessary dead time in conventional auto-reclosing methods and enable an optimal reclosing operation in the event of a single-pole to ground fault. The proposed ASPAR scheme is implemented using the electromagnetic transient program (EMTP), and various simulations are conducted for actual 345 and 765 kV Korean study systems.

Identification of Single-Phase Reclosing Fault on AC Line Based on Virtual Instantaneous Power

Concerning the difficulty in distinguishing between permanent and transient faults on AC line in AC/DC hybrid system due to relatively low amplitudes of fault recovery voltage and fault arc voltage, a method to identify single-phase reclosing fault based on virtual instantaneous power is proposed. First, by analyzing AC-side networks in the case of permanent fault and transient fault, the calculation models of instantaneous power difference between two ends of AC line are built. And then, the instantaneous power difference is decomposed into two parts: virtual instantaneous power which is affected by the currents on two line ends and virtual instantaneous power which is affected by the current on one line end alone. On this basis, according to the feature of virtual instantaneous power affected by the currents on two line ends, i.e., it is 0 in the case of transient fault, but not 0 in the case of permanent fault, a fault nature identification criterion to distinguish between permanent and transient faults is constructed. Finally, simulation tests on RT-LAB platform verify that, the proposed method can correctly identify the fault nature and determine the fault arc extinction time in both permanent and transient fault cases, unaffected by the commutation failure and fault resistance.

Dynamic control of current and voltage waveforms and droplet transfer for ultrasonic-wave-assisted underwater wet welding

Ultrasonic vibration can change the dynamic behavior of the bubble and improve the process stability in underwater wet welding (UWW); thus, it has been attempted to profitably control metal transfer process. Arc signals about welding current and arc voltage together with the high-speed imaging detected in conventional UWW and ultrasonic-wave-assisted UWW (U-UWW) were used as information source for determining the droplet transfer mode. The results show that the change in the characteristics of bubble motion affects the droplet transfer process in U-UWW. During the short-circuiting transfer process in small arc voltage, the frequency of arc extinction and the peak of short-circuiting current are both decreased. During the droplet repelled transfer process in middle arc voltage, the droplet repulsive phenomenon is weakened, and the transfer frequency is increased from 7.9 Hz to 10.5 Hz at 34 V. Meanwhile, the droplet diameter is reduced and its transfer stability is improved. During the droplet repelled transfer process in high arc voltage, the frequency and duration time of arc extinction are both reduced. The underlying difference of droplet transfer process between conventional UWW and U-UWW was investigated by the two aspects including ultrasonic wave effect and dynamic bubble effect.

A novel adaptive auto-reclosing scheme for transmission lines with shunt reactors

In this paper, a novel adaptive single-phase auto-reclosing method for high voltage transmission lines with shunt reactors is presented. The proposed method applies a low-pass filter and the cascaded delayed signal cancellation (CDSC) technique to the fault phase voltage in order to reveal different characteristics between transient and permanent faults. For transient fault, the fundamental and oscillation components of arc voltage are retained, while in permanent fault situation, only the fundament component is preserved. Based on the above analysis, the average distortion rate (ADR) and the corresponding threshold are designed to discriminate transient and permanent faults and also to identify the arc extinction time if the fault is transient. The proposed method is easy to implement with small computation. Simulation results based on EMTP and calculation results based on Matlab as well as the result of a real case relate to a 500 kV transmission line validate the performance of the proposed method.

Comparison and analysis of the fault arc characteristics of flexible DC transmission lines

VSC-HVDC grid is one of the important development directions of the smart grid in the future. The arc characteristics of transient fault on the transmission line are the theoretical basis for determining reclosing time and reclosing strategy of DC circuit breaker. In this study, the process of the transient single-pole ground fault on the true bipolar VSC-HVDC transmission line is analysed and the arc model of the fault is determined according to the fault characteristics. Then a two-terminal voltage source converter-high voltage direct current (VSC-HVDC) system including this arc model is built in power systems computer aided design (PSCAD). The primary and secondary arc characteristics of the transient single-pole ground fault on the transmission lines are simulated and compared with the arc in AC system. It is shown that the arc extinction time of the flexible DC transmission system is lesser than that of the AC system at the same voltage level.

Determining secondary arc extinction time for single-pole auto-reclosing based on harmonic signatures

In this paper, a new algorithm based on harmonic signatures is proposed to detect extinction of secondary arc for single-pole auto-reclosing (SPAR). In the proposed algorithm, the TT-transform is used to highlight harmonics of healthy phase voltages. The criterion for the detection of extinction of secondary arc is harmonics amplitudes, which is calculated after the TT-transform. The algorithm is noncommunication and the threshold value is adaptive; therefore, for various transmission systems no special adjustment is needed. To evaluate the accuracy of the proposed scheme, numerous simulations under different conditions including fault location, fault inception angle and line compensation are performed, in all of which the highest reliability is achieved.

An adaptive three-phase reclosure scheme for shunt reactor-compensated transmission lines based on the change of current spectrum

In this paper, a new three-phase adaptive reclosing scheme for transmission lines with shunt reactors is proposed to identify fault nature and determine the arc extinction time under the single and double-phase-to-ground faults. According to the fact that the faulted phase currents of shunt reactors contain only one oscillating frequency before the fault extinction and contain other two different oscillating frequencies when the fault is extinguished, this change of current frequency can be used to distinguish transient faults. When sampling rate is an integral multiple of the faulted phase current frequency of shunt reactors under permanent faults, an abrupt increase of currents even harmonics which is caused by spectral leakage of the DFT algorithm under non-synchronous sampling can lead to identify transient faults and three-phase reclosing. Electromagnetic Transient Program simulation results verify the correctness of the frequency spectrum characteristic analysis of the faulted currents of shunt reactor. The feasibility of the proposed scheme is also tested under different fault condition.

Adaptive single-phase auto-reclosing method using power line carrier signals

This paper proposes a new method for adaptive single-phase auto-reclosing (ASPAR) that improves the rate of successful reclosing actions after the occurrence of a transient single-phase fault and prevents unsuccessful reclosing. After the occurrence of a fault, the only faulty phase is disconnected by the protection system (e.g., distance relays and circuit breakers). The proposed method deploys power line carrier (PLC) signals for determination of the secondary arc extinction time and releasing the reclosing signals to the circuit breakers. Despite the growing use of new communication systems (e.g., fibre-optic links), PLC systems are still widely used, and may not be considered for replacement in near future. Therefore, the proposed method can be utilized as an auxiliary application of PLC systems to enhance the resiliency of power grids. The simulation studies are carried out using EMTP-RV and MATLAB, and the advantages and disadvantages of the proposed method are discussed and compared with the existing ASPAR methods. According to the simulation results, the efficiency of the proposed ASPAR method is negligibly influenced by the following factors: fault location, faulty phase, system loading, transmission line transposition, shunt reactor, PLC carrier frequency, PLC operating mode, and the noises.

Analysis of Secondary Arc Extinction Effects according to the Application of Shunt Reactor and High Speed Grounding Switches in Transmission Systems

When secondary arc is caused by single phase tripping, arc should be extinguished prior to high speed reclosing which can make the system restore. In this paper, we analyzes secondary arc extinction by applying two methods that are shunt reactor and High Speed Grounding Switches (HSGS). To verify the effects of these methods in arc extinction aspects, two factors are discussed. One is secondary arc extinction time, and another is recovery voltage. Especially, secondary arc waveform and amplitude value are analyzed to identify the effects of arc extinction methods. Simulation is conducted by using ElectroMagnetic Transient Program (EMTP) based on actual Korea 765kV transmission system.