Location Scheme Research Articles

Dynamic Optimization of Exclusive Bus Lane Location Considering Reliability: A Case Study of Beijing

For metropolises like Beijing, heavy congestions cause transit passengers’ unreliable travel time, including in vehicle time and waiting time. Comparing with other managerial measures, designing a lane for bus use only is an effective method to improve travel reliability, for it can eliminate the influence on bus-driving conditions. This paper proposes a reliable and practical method to determine exclusive bus lanes (EBL). A reliability-based optimization model is established, in which the tradeoff among bus and private car passengers’ travel time, reliability, and EBL construction cost are considered. Based on the actual network, a user equilibrium demand assignment model is applied to estimate the dynamic bus flow distribution. Since the model is nonlinear, a two-step method is proposed where tangent lines are introduced to constitute an envelope curve to linearize the model. This work conducts the statistical modeling and fitting analysis with actual bus trajectory data, collected on EBL in Beijing during peak hours. Passenger travel time distributions are fitted to estimate the statistical passenger travel time; Lognormal distribution and Gaussian distribution are the best fit. The optimization results indicate that the passenger travel time reliability can be improved by 5.5% by the optimized EBL location scheme. This study will provide a theoretical basis and methodological support for improving the service level of the public transportation system in large cities through the scientific planning of exclusive bus lanes.

Time-Domain Fault Detection and Location Scheme for Flexible DC Distribution Networks

Accurately detecting and locating the fault point of the DC line is significant for eliminating the fault and restoring the power supply of the flexible DC distribution network as soon as possible. Firstly, a direction pilot protection scheme for a complex DC distribution network is proposed based on the integral of the current superposition to identify the fault direction. Then, an online time-domain fault location method based on the least square (LS) method to solve the overdetermined equations is proposed by analyzing the fault loop circuit after the DC line fault. The proposed location scheme utilizes fault data at both ends of the line to eliminate the theoretical impact of fault resistance, and the calculation of the current difference method is discussed to reduce the location error of whether the fault current-limiting reactor (CLR) exists. Finally, various simulations by PSCAD/EMTDC V4.5 demonstrate that the proposed scheme has high protection reliability and location results after different fault positions and resistances. The proposed scheme has low requirements for the sampling rate, fault data length, and implementation costs, which can meet practical application requirements.

An approach to robot welding path autonomous planning of the intersection weldment based on 3D visual perception

To improve the accuracy, an approach to robot welding path planning of the intersection weldment based on 3D visual perception is proposed. It adopts the two-stage location scheme of “global 3D reconstruction + local scanning correction”. First, this paper proposes an improved K-means clustering method based on the geometric features of workpiece point-cloud, to achieve accurate and fast point-cloud segmentation. Second, the intersection parameters of workpiece can be quickly calculated by the proposed parameter identification method. Third, this paper plans the scanning path of laser scanner according to the identified parameters, and puts forward an algorithm of weld path points recognition combined with the actual weldments state. Then, the pose of robot welding torch is obtained by using spline fitting algorithm and welding torch attitude estimation algorithm. Finally, the experiments show the path planning error is about 0.3 mm, which has increased a lot than the published methods.

Two-terminal traveling wave fault location approach based on frequency dependent electrical parameters of HVAC cable transmission lines

With the expansion of high-voltage alternating current transmission networks, the widely used two-terminal traveling wave method faces several challenges in cable fault location. On one hand, the frequency dependent characteristics of longer cable transmission lines can significantly impact the accuracy of traveling wave propagation velocity. On the other hand, the processing of traveling wave signals obtained synchronously is also a crucial factor that requires attention. To enhance the performance of cable fault location, the principles of two-terminal traveling wave method need to be updated. Firstly, the cable model derived from the theory of wave propagation in multi-conductor systems is presented, which reflects the frequency dependent characteristics of the electrical parameters. Whereupon, an innovative cable traveling wave fault location scheme primarily composed of arrival time identification and instantaneous frequency calculation is proposed. Eventually, based on electromagnetic transient simulation software PSCAD/EMTDC, the robustness of the innovative cable fault location method against fault type, fault location, fault resistance, fault initial angle and earth resistivity issues is demonstrated.

Location-routing optimization problem for electric vehicle charging stations in an uncertain transportation network: An adaptive co-evolutionary clustering algorithm

The rapid growth of Electric Vehicles (EVs) has led to issues such as insufficient and unevenly distributed charging stations, posing an increasingly severe challenge. This not only means higher economic and time costs for EV users traveling to charging stations, but also indicates that EVs need to incur additional energy consumption. To address these challenges, this paper first establishes an extended space-time-state network to describe the temporal variability and uncertainty of the traffic environment. Secondly, considering the impact of the energy consumption incurred by EVs traveling to charging stations (CSs) on the layout of CSs, a co-evolutionary optimization model of the location-routing problem is proposed. To solve the model, a two-stage Adaptive Co-evolutionary Clustering Algorithm (ACECA) integrating an adaptive clustering framework and a co-evolutionary mechanism is designed. Finally, the experiment results indicate that there exists a game between a short-term economic investment and long-term benefits of energy conservation and emission reduction. Moreover, ACECA demonstrates stronger solution performance and robustness compared to other algorithms, with the resulting CS location schemes showing superior advantages in energy conservation and in cost saving for users. The research findings can provide theoretical support for the planning of charging station locations for electric vehicles.

Data-driven traffic sensor location and path flow estimation using Wasserstein metric

This paper introduces link information value obtained by the traffic sensors and presents a traffic sensor location and flow estimation joint optimization model in an urban road network. In contrast to most previous studies, this paper adds new traffic sensors into the existing sensor network and proposes a data-driven path flow measurement method based on Wasserstein metric, which is utilized to measure the distance between the estimated traffic flow distribution and the actual distribution. Furthermore, this paper develops a customized greedy algorithm by combining a search strategy for the link information value to obtain the optimal sensor location scheme and perform traffic flow estimation under different budget conditions. Numerical experiments are conducted on Sioux-Falls test network and Eastern Massachusetts interstate highway subnetwork to verify the accuracy and effectiveness of the proposed model based on Wasserstein metric and the developed solution method. Computational results show that the sensor location scheme generated by the model based on Wasserstein metric can reduce the estimation error of the traffic flow compared with KL divergence model under the same deployment cost. Additionally, the customized greedy algorithm can achieve the better performance than the Brute force algorithm in terms of computing time and solution quality.

Introducing ViDA3, An Earthquake Early Warning Algorithm for Offshore Hypocenter Determination Using Onshore Seismic Networks

ABSTRACT The objective functions adopted by earthquake early warning (EEW) location algorithms are inadequate for out-of-network earthquakes. As a result, the real-time locations of these earthquakes are often erroneous. The consequences of mislocating out-of-network earthquakes are that their magnitudes are miscalculated, and the loci of their shaking predictions map are shifted. Given that the largest earthquakes occur in subduction settings, improving real-time out-of-network earthquake location is of great importance. In this study, the Virtual Dynamically Assembled Array Algorithm (ViDA3) is introduced, which addresses the location issue of offshore and off-network earthquakes. The guiding principle underlying the new EEW location algorithm is that standard seismic networks may be viewed as a collection of medium-sized seismic arrays, with each array consisting of three or more network stations. The potential of array seismology for EEW against out-of-network earthquakes stems primarily from the slowness vector, which points at the direction of the epicentral region. Thus, this region may be constrained merely by intersecting two or more such vectors. In addition, the length of the slowness vector depends on the hypocentral distance and depth and is thus vital for addressing an acute problem in a subduction setting—discriminating between upper crust and deep slab earthquakes. Furthermore, when the slowness of the P phase is known, the slowness of the S phase is deduced, and the S-phase arrival is searched for using the shift-and-sum practice. What makes ViDA3 so attractive is that, in locations where a real-time network is already in place, these added values may be achieved without extra hardware or substantial budget requirements. We present the result of ViDA3 real-time operation on a shallow earthquake offshore Vancouver Island and the result of its replay on a deep slab earthquake in northern Chile. ViDA3 performance is further assessed using a dataset of seismograms from the Mendocino Triple Junction area. It is concluded that ViDA3 location scheme outperforms currently available EEW location algorithms for out-of-network earthquakes.

Multi-agent system-assisted fault section location scheme for distribution networks with DFIG-based wind DGs

This paper proposes a multi-agent system (MAS)-assisted relaying scheme to identify the fault section in a distribution network (DN) that incorporates doubly-fed induction generators (DFIG)-based wind distributed generations (DGs). Firstly, to mitigate the adverse effect of the uncertain fault behavior of DFIGs on conventional directional elements, the fault direction identifiers (FDIs) are assigned at the I-type and II-type buses in the DN using the high-frequency component principle. Furthermore, a MAS-assisted relaying structure is devised to collect and integrate these identifiers and then accomplish the fault section location. On the one hand, since the setting of FDIs only requires local current information and the logical signals are solely exchanged within each predetermined associated region, the proposed fault section location scheme can be implemented in an immature DN with a limited number of voltage transformers or under weak synchronization conditions. On the other hand, the autonomy and cooperation of intelligent Agents also enable the proposed scheme to determine the fault section in a decentralized decision-making (DDM) mode, eliminating the dependence on strong central control and reducing redundant data transmission in a multi-bus distribution system. Simulation results under representative faulty scenarios validate the expected performance of the protection scheme.

Towards Building a Faster and Incentive Enabled Privacy-Preserving Proof of Location Scheme from GTOTP

In recent years, there has been significant growth in location-based services (LBSs) and applications. These services empower users to transmit their location data to location service providers, thereby facilitating the provisioning of pertinent resources and services. However, in order to prevent malicious users from sending fake location data, users must attest to their location for service providers, namely, through a proof of location (PoL). Such a proof should additionally prevent attackers from being able to obtain users’ identity and location information through it. In this paper, we propose an efficient privacy-preserving proof of location (PPPoL) scheme. The scheme is based on the standard cryptographic primitives, including Group Time-based One-Time Password (GTOTP) and public key encryption, which achieves entity privacy, location privacy, and traceability. Unlike the previous GTOTP-based PPPoL scheme, our scheme enables instant location verification with additional hash operations. To encourage the active participation of witnesses in location proofs, we propose an incentive mechanism based on smart contracts. Additionally, we implement a proof of concept of our PPPoL scheme on an Android device. Our experimental results show that proof generation and verification time are on the order of milliseconds. Meanwhile, the total overhead for the incentive mechanism amounts to 0.0011 ETH. This result is practical for mobile device-based LBSs.

Multi-Type traffic sensor system design for multi-period network-wide speed-flow estimation with day-to-day uncertainties

Owing to budget limitations, traffic sensors cannot be installed on each link of a road network in practice. Thus, optimizing the locations of a limited number of sensors is crucial for development of various intelligent transportation systems. This paper devises a multi-type traffic sensor location model with consideration of day-to-day flow variations by hourly period. Based on the devised model, network-wide link speeds and flows in multiple periods, even on those links without installed sensors, can be estimated. The link speed and flow estimator is formulated as a bi-level model, in which the upper-level model estimates multi-period origin–destination (OD) demands, and the lower-level model assigns the resultant OD demands onto the study network to obtain the hourly link flows and speeds. The case studies on both synthetic and real road networks demonstrate the cost-effectiveness of the multi-period multi-type sensor location scheme and provide valuable insights.

A fault location scheme based on composite traveling wave with transients in adjacent fault-free lines

As the speedy expansion of power gird, the traveling wave fault locator in substation may not always connect to newly added transmission lines in time, which reduces the effectiveness of fault locator. In this paper, an adjacent fault-free line based fault location scheme for newly additional line is proposed. Since the traveling wave from adjacent fault-free line results in severe difficulty for identification of traveling waves from faulty line, the time–frequency matrix is performed to screen traveling waves. Firstly, in order to remove the influence of waves from remote terminals of adjacent fault-free line, the current refraction coefficient is theoretically analyzed. Due to the negative refraction coefficient, traveling waves from remote terminals of adjacent fault-free line can be reduced by the proposed composite traveling wave. Secondly, the time–frequency matrices of composite traveling wave and original traveling wave is obtained by S-transform. Then, these matrices are applied to form ratio matrix which thoroughly eliminated waves from remote terminals of fault-free lines. Moreover, the robustness of the proposed fault location scheme is thoroughly validated by the simulation of PSCAD/EMTDC. Finally, the proposed fault location method has the great accuracy in simulation tests and field data test.

Determining the optimal placement scheme and height of elements that accelerate heat exchange processes in solar air heater collectors through mathematical modeling

In the article, the heat exchange accelerating elements used in the collectors of solar air heaters were investigated by thermal and hydraulic mathematical modeling by changing the location scheme and geometric dimensions in homogeneous environment. In this case, the height of the gap between the flat absorber and the transparent glass was 60 mm. The height of elements that accelerate heat exchange processes has increased from 10 mm to 60 mm. The location scheme is laid out in a corridor and a checkerboard pattern. According to the modeling results, the results of the solar air heater collector with the rhombic heat exchange accelerating element were found to be high.

Location of Faults in Six Phase Transmission Line using a Neuro Fuzzy System

Fault location plays an important role in power systems. It is frequently used in transmission lines to reduce the system damage for growing electrical energy demand. However, the location estimation method itself is easy to be disturbed by different parameters and gives estimation errors. To solve this problem, this paper introduces a scheme that uses neuro fuzzy system (NFS) to locate all types of faults such as shunt faults, transforming faults, series faults and simultaneous faults in six phase overhead line (SPOL). This scheme has been performed on a 68 km, 138 kV, 60Hz, SPOL for all fault types by employing MATLAB software Simulink. Here, Haar wavelet transforms (HWT) are used to extract the current signals in order to evaluate the behavior and characteristics of higher frequency components. Then, the obtained HWT currents data are employed to construct the fault location scheme in SPOL based on NFS. The obtained experimental results confirm that by using the NFS, the maximum fault location error (MFLE) can be reduced by more than 10%. It can further reduce the maximum response time (MRT) for the operator to address the faults and ensure the power system reliability in the future. The test result executed in this investigation indicates that the NFS is resilient to wide changes in fault conditions, and it shows good performance and huge potential for location of faults in SPOL.

Online Detection and Location Scheme for Aged Cable Segment in MMC-HVDC Systems Based on Admittance Spectrum and Compressed Sensing

Online Detection and Location Scheme for Aged Cable Segment in MMC-HVDC Systems Based on Admittance Spectrum and Compressed Sensing

A new fault location scheme based on local measurements for transmission lines connected to inverter-based resources

This paper aims to reveal conventional impedance-based fault location methods’ shortcomings in the presence of inverter-based resources (IBRs) through an analytical framework established for the analysis of the IBR sequence impedances. Thereafter, a single-ended method is put forward in order to accurately specify the fault location in the lines emanating from the IBRs. The proposed fault location formulation utilizes the negative and zero sequence currents as alternative polarizing currents, therefore it is independent of the pre-fault data, and it can be applied for all kinds of asymmetrical short circuit fault. Furthermore, the established formulation is further amended to make it applicable to long transmission lines. The suggested method also provides acceptable accuracy in various conditions, such as different fault resistances, different host grid codes, and dynamic behavior of the fault resistance. The performance of the proposed scheme is scrutinized using the PSCAD/EMTDC software with an extensive number of simulations. The obtained results reveal the effectiveness and efficacy of the proposed fault location method in the presence of IBRs.

Fault nature identification and location scheme for distribution network based on active injection from IIDG

In view of the difficulty in passively identifying the nature of faults in distribution networks and the high equipment cost of existing active detection schemes, a permanent fault identification and location scheme using an inverter-interfaced distributed generator (IIDG) connected to feeders for signal injection is proposed. After the faulty feeder is isolated, the power electronics in the IIDG are switched on for a short time and a voltage signal is injected into the feeder through the modified LCL filter and grid-connected transformer. The analysis shows that the aerial mode voltage of the feeder will not remain 0 under permanent faults. A highly sensitive criterion with fixed thresholds is constructed using approximate entropy (ApEn) to identify fault nature. Then the fault distance is further calculated based on the detected mutation point of the aerial mode voltage under permanent faults. The correctness of the theory and the effectiveness of the scheme are verified in PSCAD/EMTDC simulations.© 2017 Elsevier Inc. All rights reserved.

A Novel Fault Identification and Localization Scheme for Bipolar DC Microgrid

Traditional fault detection and location schemes become ineffective for detecting and locating the fault in DC microgrid systems due to integrating various types of power electronic-based DC loads and generators. To resolve this issue, advanced, intelligent, specialized fault detection and location schemes are necessary. This article suggests a novel fault detection scheme based on the difference in the teager energy available in the DC current wave at sending and receiving ends of lines. After the detection of the fault, the location is calculated by estimating the resistance of the cable up to the fault point as well as the total resistance of the cable, with the help of least square technique. The proposed scheme decides fault is internal if the estimated fault location is less than 1 p.u. Otherwise, the proposed scheme decides fault is external. A DC microgrid with different types of generating units and loads is simulated using MATLAB/SIMULINK to evaluate the developed algorithm. Internal and external faults, pole-to-ground and pole-to-pole faults with changing fault resistance and fault location are some of the fault scenarios that have been simulated. The obtained simulation results prove that the suggested algorithm can discriminate between internal and external faults and locate the fault. The proposed technique is also examined on a DC microgrid hardware testbed and results show the efficiency of the suggested approach.

A Flexible DC Ranging Scheme Based on Variational Mode Decomposition and Teager Energy Operator

In this paper, a new Cable fault location scheme is proposed for the existing flexible DC Cable fault location methods, in which the fault signal is mixed with noise and the traveling wave speed is affected by line parameters. This scheme is based on the propagation characteristics of fault line mode voltage traveling waves in flexible DC transmission. Firstly, the fault voltage is effectively decomposed using Variational Mode Decomposition (VMD). Then, the decomposed intrinsic mode functions (IMF) are reconstructed to obtain the high-frequency components of the recorded fault information. Finally, the traveling wave head is calibrated using the Teager Energy Operator (TEO). A dual terminal ranging algorithm that is not affected by wave velocity has been proposed, which can effectively avoid the impact of fault traveling wave velocity uncertainty on the ranging results. A dual ended flexible DC power grid model was built in PSCAD/EMTDC, and a large number of simulation results show that the algorithm proposed in this paper can accurately calibrate the fault traveling wave head, has little interference from transition resistance, strong noise resistance, and can obtain high-precision fault location results in different fault locations.

Automated fault location scheme for low voltage smart distribution systems

AbstractIntegrating the self‐healing capability realizes the automated protection of smart distribution systems. This article presents a fault location scheme for low voltage (LV) distribution systems based on the information collected from the smart meters. First, a fault condition is detected and classified by processing the current signal at the secondary side of the distribution transformer by an intelligent electronic device. Then, the faulty feeder and section are determined by calculating the fault‐imposed component of nodal voltages. The reliable performance of the proposed scheme is verified through several case studies using a real semi‐rural distribution system.

Fault Location Scheme for Multi-Terminal Transmission Line Based on Frequency-Dependent Traveling Wave Velocity and Distance Matrix

Fault Location Scheme for Multi-Terminal Transmission Line Based on Frequency-Dependent Traveling Wave Velocity and Distance Matrix