Fast Tripping Research Articles

New challenges for sustainable urban mobility

Micromobility provide intelligent, fast, and sustainable trips for tourist from accommodation facilities to attraction locations. However, some points of interest may be located away from the accommodation i.e. in a different city of a metropolitan area. In this case, cycling to the attractions may not be possible and multimodal bike and public transport trips can be considered for more sustainable tourism. Therefore, it is essential to identify how adequate a city transport infrastructures and services are for these types of trips. In this paper, we propose a cycling indicator for tourism accessibility with the aim of defining the level of multimodal bike-public transport friendliness through numerical values related to a specific zone in the main city of a metropolitan area. The indicator was applied to the metropolitan area of Bari (Italy) and results showed that the presence of bike lanes and bike-sharing plays an important role.

Correcting missingness in passively-generated mobile data with Multi-Task Gaussian Processes

The prevalence of mobile devices and the ubiquity of network connectivity have generated a massive amount of temporally- and spatially-stamped data. A key characteristic of this mobile data is the prevalence of sparsity—for every recorded user, there is a significant amount of missing data. Sparsity leads to bias in the inferred mobility patterns and thus, correcting bias by imputing the missing data potentially creates opportunities for directly using the corrected mobile trajectory data for large-scale simulations in various applications. We propose a multi-task Gaussian process regression model to correct missingness in mobile data. Gaussian processes (GPs) allow for flexible modeling of diverse (i.e., non-linear, locally periodic) data patterns and quantify prediction uncertainty in an interpretable manner. We develop a methodological framework for applying GPs to mobile data. In doing so, we consider the correlations between users’ coordinates (latitudes and longitudes) through multi-task learning and adjust for individual-level differences in data characteristics through parameter initialization and optimization. We introduce and demonstrate the use of smooth (i.e., rational quadratic) and periodic kernels in modeling human mobility data. Relatedly, we analyze our model’s parameters and imputation accuracy with respect to different types of trips (e.g. slower vs faster trips). We also demonstrate our model’s performance in two experiments with real app-based data, in which it outperforms alternative imputation methods. Our implementation is open-source at https://github.com/ekinugurel/GPSImpute.

Design and Research on the Drilling and Lifting Device of Coalbed Methane Drilling Machine

In response to the problems of complex operation procedures, long auxiliary time, and impact on drilling efficiency in coalbed methane drilling construction, a fast tripping and lifting device for coalbed methane drilling rig is designed. The device has a compact and reasonable structure, and strong process adaptability; The structure of clamping with a wedge-shaped groove and releasing the basket is used. In the drilling operation of the drill-ing rig, the drilling rod is clamped with a lifting device instead of a threaded connection, and the lifting and lowering of the drilling rod is completed with the help of a rotator. The operation is simple, reducing auxiliary time and improving drilling efficiency. Simultaneously using a self sealing floating core tube structure and hydraulic pressurization, the sealing between the lift-ing device and the drilling tool can be achieved. During drilling operations, mud can be directly introduced for drilling, improving the ability to handle drilling accidents.

An Accelerated Distance Protection Scheme for the Lines Connected to Inverter-Based Resources

Distance relay based pilot protection schemes are commonly employed in industrial relays to provide fast tripping of the faulty transmission lines. However, the probable communication link failure or interruption can make these schemes ineffective. Therefore, some non-pilot methods are addressed in the technical literature which cannot offer an appropriate performance in the presence of inverter-based resources (IBRs) owing to the unconventional fault behavior of IBRs as compared with that of synchronous generators. Thus, an analytical non-pilot method is established for the accelerated tripping (AT) of the second zone of distance relay in the presence of IBRs. At the first place with the proposed method, the faulted phase is identified through a fault classification scheme. Within the second phase, using the strength of the variations existing in the negative and zero sequence components of both voltage and current signals, the remote breaker status is realized. Finally, according to the remote breaker status, the AT or delayed tripping decision is decided. Performance of the established methodology is examined for different simulation scenarios, such as different fault locations as well as fault resistances, employing the PSCAD/EMTDC software. The obtained promising results obviously approve the efficiency of the proposed framework.

The Use of Instantaneous Overcurrent Relay in Determining the Threshold Current and Voltage for Optimal Fault Protection and Control in Transmission Line

When a fault occurs on the transmission line, the relay should send the faulty signal to the circuit breaker to trip or isolate the line. Timely detection is integral to fault protection and the management of transmission lines in power systems. This paper focuses on using the threshold current and voltage to reduce the time of delay and trip time of the instantaneous overcurrent relay protection for a 330 kV transmission line. The wavelet transforms toolbox from MATLAB and a Simulink model were used to design the model to detect the threshold value and the coordination time for the backup relay to trip if the primary relay did not operate or clear the fault on time. The difference between the proposed model and the model without the threshold value was analysed. The simulated result shows that the trip time of the two relays demonstrates a fast and precise trip time of 60% to 99.87% compared to other techniques used without the threshold values. The proposed model can eliminate the trial-and-error in programming the instantaneous overcurrent relay setting for optimal performance.

High-Frequency Fault Analysis-Based Pilot Protection Scheme for a Distribution Network With High Photovoltaic Penetration

Due to the influence of inverter control, the short-circuit current provided by distributed photovoltaics (PVs) exhibits new characteristics, such as a controlled amplitude and phase angle, resulting in the malfunction of the current protection and differential protection of distribution networks with high PV penetration. In this paper, the equivalent high-frequency impedance model (EHFIM) of PV power generation and the analysis method of a fault high-frequency superimposed network are proposed. On this basis, we analyze the fault high-frequency superimposed network of a distribution network with high PV penetration and propose a high-frequency fault analysis-based pilot protection scheme, in which the range of frequency employed for protection (FEP) is analyzed theoretically. By comparing the relationship between the high-frequency operating impedance and the high-frequency restraining impedance, the internal and external faults are identified. The proposed protection scheme has the advantages of a fast trip, low requirement for data synchronization, immunity to inverter control and the PV operation mode, and adaptability to lines with teed feeders. The experimental results show that the proposed protection scheme can accurately identify internal and external three-phase, two-phase, and two-phase grounding faults and is resistant to both fault resistance and noise interference.

Beam dynamics studies for fast beam trip recovery of the Japan Atomic Energy Agency accelerator-driven subcritical system

High reliability and availability are primary goals for the operation of particle accelerators, especially for accelerator-driven subcritical systems (ADS). ADSs employ high-power beams for the transmutation of minor actinide; as a result, the amount and the radiotoxicity of the nuclear waste are considerably reduced. To this end, the Japan Atomic Energy Agency is designing a 30-MW continuous wave (cw) superconducting proton linear accelerator (linac) that supplies neutrons to an 800-MW subcritical reactor by a spallation process. The major challenge for an ADS linac is the strict control of the beam trip duration and its frequency to avoid thermal stress in the subcritical reactor structures. The maximum allowed beam trips for failures longer than a few seconds are estimated to be far below the rate achieved in current accelerators. Thus, we implemented a combination of hot standby and local compensation that enables a fast beam recovery. This work comprehensively investigated the tolerance of our linac lattice for the local compensations for failures in superconducting cavities and magnets. This scheme includes simultaneous compensation of multiple cavities in independent and same cryomodules that significantly enhance the reliability of the linac. The retuned schemes present acceptable beam performance to guarantee the integrity of the linac and the beam transport to the target; moreover, they satisfy the beam stability in the beam window. In addition, the readjusted elements are subjected to moderate stress to ensure a sustainable operation. This manuscript reports the beam dynamics results toward fulfilling the high reliability demanded by an ADS linac.

Investigation on Fault Analysis for Power Transformers Using Adaptive Differential Relay

This article presents the fault analysis and differential protection scheme of the three phase Power Transformers (PT). The relay operates mainly during the internal fault condition and it must be insensitive to any fault outside the zone of protection. In this paper, a fuzzy logic based differential protection schemes has been used. It blocks the tripping through outer fault and internal fault conditions. The simulation result of FLC with disparity relay for 3 phase transformer shows fast tripping during internal fault and also avoids the mal operation of relay during external fault.

Distance relaying of Untransposed parallel transmission lines in case of phase-phase inter-circuit faults

• Untransposed parallel transmission lines are targeted for distance relaying. • Phase-phase inter-circuit faults are addressed in the distance relaying. • The ADALINE is developed for an accurate online estimation of the fault distance. • The proposed approach achieves fast fault tripping and an accurate fault location. • It tolerates noisy conditions and properly handles variable fault arc resistance. Distance relays at both circuits of the parallel transmission lines would miscalculate the right fault impedance during inter-circuit faults. This paper deals with the distance relaying of untransposed parallel lines in case of phase-phase inter-circuit faults. It is a challenging case compared to that of transposed lines due to the mutual coupling between all six phases of the line circuits. Considering a phase-phase inter-circuit fault with the fault arc resistance, the line circuit model is analyzed on a time-domain basis. Consequently, a mathematical equation with a linear combination of specified functions is derived. This provides a splendid opportunity to establish an ADAptive LINEar combiner (ADALINE) consistent with the equation derived. The ADALINE with its simple structure gives a fast and accurate online estimation of the fault distance, employing single-end measurements during the inter-circuit faults. Hence, achieving the fault location along with the distance protection is also made possible. The proposed approach is readily implementable without being dependent on the system configuration. It operates robustly against the dynamic fault arc resistance and tolerates the noise contamination. The simulations in PSCAD/EMTDC provide extensive sensitivity analyses validating the proposed approach performance, in respect of both the accuracy and swiftness, for various fault conditions.

Joseph Smith Sr.’s China Adventure

Joseph Smith Sr.’s China Adventure

Fault control and line protection strategy for LVDC microgrids based on modified high-frequency-link DC solid state transformer

Fault current with high amplitude and rate of change, together with the vulnerability of electronic devices, poses a great challenge to the line protection in low voltage DC (LVDC) microgrids. A fast fault control and protection method are proposed for LVDC microgrids, based on the modified topology of the high-frequency-link DC solid state transformer (DCSST). By installing two bidirectional antiparallel thyristors in the DCSST and isolation devices at the interface converter side, the freewheeling diodes are protected and current zero-crossings occur due to the submodule capacitor discharge during the fault. Then the line protection could be realized by improved current differential protection, and the mechanical circuit breaker can be tripped around current zero-crossings. It alleviates the high requirement for fast tripping devices (such as solid-state circuit breakers) and fault identification within several milliseconds. The scheme combines the converter fault control with line protection to ensure slow but more economic and reliable fault identification for LVDC grid protection. The proposed strategy is verified by PSCAD/EMTDC simulations and the results show that the fault-tripping-recovery process only takes few tens of milliseconds.

DC microgrid fault detection using multiresolution analysis of traveling waves

Fast detection and isolation of faults in a DC microgrid is of particular importance. Fast tripping protection (i) increases the lifetime of power electronics (PE) switches by avoiding high fault current magnitudes and (ii) enhances the controllability of PE converters. This paper proposes a traveling wave (TW) based scheme for fast tripping protection of DC microgrids. The proposed scheme utilizes a discrete wavelet transform (DWT) to calculate the high-frequency components of DC fault currents. Multiresolution analysis (MRA) using DWT is utilized to detect TW components for different frequency ranges. The Parseval energy of the MRA coefficients are then calculated to demonstrate a quantitative relationship between the fault current signal energy and coefficients’ energy. The calculated Parseval energy values are used to train a Support Vector Machine classifier to identify the fault type and a Gaussian Process regression engine to estimate the fault location on the DC cables. The proposed approach is verified by simulating two microgrid test systems in PSCAD/EMTDC.

A new time domain-based busbar protection algorithm

This paper presents a new time domain busbar protection algorithm which uses current samples and their half-cycle incremental quantities to implement a fast and reliable tripping logic. The sign of incremental quantities is used to determine the fault direction and to distinguish internal from external busbar faults. Also, a differential incremental current is calculated for properly selecting the circuit breakers that must be opened to clear the fault. In order to test the proposed technique, a double-bus single-breaker busbar configuration was modeled in ATP/ATPDraw software and several types of internal, external and evolving faults are simulated. The results reveal the proposed function quickly operates for internal faults and ensures security for external faults. Moreover, the proposed approach allows a fast detection of internal faults during an external fault. Hence, although the proposed function is based on well-known fundamentals, it achieves the principal requirements for a busbar protection scheme with a high degree of adaptability and reliability for severe cases.

Development of High-Current Solid-State Power Controllers for Aircraft High-Voltage DC Network Applications

Solid-state power controllers (SSPCs) have been received increasing attention as they can configure the electrical system and protect the system by fast tripping mechanism at the same time. Although the high-voltage direct current (HVDC) electrical system can bring sustainable savings on the cables' weight and losses, the protection can be considerably challenging. SSPCs have been successfully utilized for 28V DC aircraft onboard network. However, high-voltage ones are impeded by the vast over-voltage and the excessive losses generated from SSPC switching. This paper tries to fill this gap and presents the development of high-power SSPCs for a ±270VDC network of a future turboprop aircraft. Comprehensive designs of proper over-voltage suppression along with SSPC thermal management are presented in this paper. Besides, a comparative study on the SSPC device is carried out. Two prototypes, including a single MOSFET module and paralleling several discrete MOSFET devices, are built and then tested in the experiment. It has been validated that the proposed voltage clamping design cannot only effectively suppress the over-voltage, but also limit the SSPC temperature increase during switching for both candidates. After comparing the conduction losses, maximum junction temperature, power density, weight and volume, the single device solution is recommended as a preferable SSPC option for future aircraft.

Protective Coordination of the OCR with the Voltage Component in a Closed-Loop Power Distribution System with the FCL

Recently, the requirement of the electrical energy from the renewable source has been growing in the South Korea since government’s energy plan to generate the electrical power of 20% as renewable source. In addition, these renewable power plants have been constructed on not only the existing power plant’s side but also customer’s side. These changes in power distribution system cause the fault current to increase higher and to reverse the direction of the fault current. Variable countermeasures to reduce the fault current have been studied and the introduction of the superconducting fault current limiter (SFCL) in the power distribution system, one of them, has been actively reported. However, the installation of the SFCL can affect the power system protection because of the fault current’s decrease or increase, which depends on the construction of the power distribution system. Especially, the application of the SFCL in a closed-loop power distribution system can cause the delayed trip operation or the fast trip operation of the over-current relay (OCR), one of the representative protective devices widely used in a power distribution system. This change can influence on the existed protective coordination. In this paper, the OCR with voltage component, one of the methods to suppress its trip operation’s change in a power distribution system with a closed loop construction due to the application of the SFCL, was suggested and the protection coordination between the OCRs in a power distribution system with a closed loop was analyzed. It was confirmed that a simple using voltage component in the OCR could cause the trip variation of the reverse direction OCR in loop power system and it can be improved by matching the relaying voltage components.

A comprehensive perspective of unreliable public transport services’ costs

In recent decades, the main focus of public transport operations has been increasing its speed. Increasing speed not only allows for faster trips but also a higher frequency with the same fleet size, thus reducing waiting times and crowdedness inside the vehicles. This interest in speed has ignored a second key dimension in the level of service: reliability. In this article, we provide a review of a full range of impacts of an unreliable public transport service. We show how regularizing headway could improve level of service beyond the gains of simply increasing the operational speed. Regular headways positively affect comfort, reliability, travel and wait time, operational costs, and even some urban impacts of bus services. Thus, the focus for public transport agencies and operators should bend into reliability’s direction. This is fundamental for making public transport an attractive travel alternative, and therefore must become a core goal for urban sustainability.

Aplikasi Weigh in Motion Menggunakan Metode Estimasi Untuk Mengukur Beban dan Kecepatan Kendaraan Bergerak

Humans as users of transportation modes, of course, want the ability of vehicles that are able to carry as much cargo as possible and on the fastest trip. This condition often results in the vehicle carrying the maximum load even exceeding the carrying capacity. On this basis and to maximize the results of data collection in the form of traffic volumes and vehicle loads, it is necessary to attempt to check the load of vehicles or trucks passing through the road without causing queues and congestion. To that can be done using a dynamic weighbridge which utilize methods of Weigh In Motion (WIM). The WIM system is equipped with the ability to measure vehicle loads when the truck runs at a certain speed through sensors placed below the road surface. The results showed that the WIM prototype can measure the speed and weight of the vehicle running successfully, the measurement results of running vehicle loads have an average error of 14.9%.

High‐speed distance relaying using least error squares method and testing with FPGA

The demand for high-speed protective relaying in modern power grids is growing. A relay's fast and secure operation to clear faults is critical, especially for EHV/UHV transmission systems (400 kV and above). This research proposes a sub-cycle distance relaying, which is based on the least error squares (LES) method, and with a data interface module implemented on field programmable gate array (FPGA). Taking advantage of inherent parallelism and pipelined architecture of the FPGA, the proposed relay design can support real-time data communications. Also, the flexible and reliable feature of the LES algorithm allows the proposed relay to make a fast and secure trip decision in different scenarios. The case studies demonstrate the effectiveness of the LES-based relay.

Study on feeding system performance of CBM carrier mounted rig

Feeding system is the main mechanism of carrier mounted rig, and determines the rig’s performance. The feeding system contains stretching mast, which pulls the drive head through two hydraulic cylinders and steel cables, as a result, the rig has a compact structure and long feeding distance. The feeding system’s hydraulic system including two pumps and two control circuits is designed to meet the demand of fast round trip and pressure’s accurate control of drilling based on the analysis of drilling procedure and load performance. The two explosionproof valves on the head end of feeding cylinders guarantee the stable suspend and avoid percussion drilling after pipelines bursting and drilling tools dropping on account of maloperation. Furthermore, the two explosionproof valves make the pressure of the two head ends of feeding cylinders equal to ensure the two feeding cylinders to run in step through control ports in parallel. In the end, ZMK5530TZJ100 is developed and applied to construct a “L” horizontal directional well with a depth of 1675 m to verify the rationality and reliability of the rig’s feeding system.

Trip patterns and revenue of shared e-scooters in Louisville, Kentucky

Data on shared e-scooters in Louisville, Kentucky are analyzed. The data includes check out times, trip duration, and trip distance. Patterns in usage are evaluated and suggest that e-scooters are probably not being used for commute trips, but potentially could be for short commutes. Daily weather data is linked to daily count data to analyze how average temperature, wind speed, precipitation and snow affects usage. Higher average temperatures are not associated with more trips but do lead to longer and faster trips. Rain and snow reduce usage while higher winds slightly reduce trip distances. An estimate of current revenue from the existing system is about $500/day.