Aerial Mode Research Articles

The Half-Sine Method: A New Accurate Location Method Based on Wavelet Transform for Transmission-Line Protection from Single-Ended Measurements

In this work, a new and accurate method based on the wavelet transform is proposed for fault location in transmission-line systems. The proposed wavelet method consists of the analysis of the transient signal measured at a single end of the transmission line. Aerial current modes are used, and zero modes are included in the fault-detection scheme for low fault-inception angles. The fault distance is evaluated using the wavelet modulus maxima technique and a method based on the response to a half-sine voltage is proposed to overcome drawbacks arising from the limited sampling frequency and low fault-inception angle. The fault distance is calculated using the difference between the time when a 100 kHz half-sine signal is sent and the time when the derivative signal is received. The proposed algorithm is tested considering harmonic distortion and varying fault resistance, ground resistivity, location and inception angle. The high accuracy of the proposed algorithm is obtained even for faults close to the bus and low inception angles.

Initial travelling wavefront‐based bus zone protection scheme

A high-speed busbar protection scheme based on initial travelling wavefronts is presented in this study. The aerial mode current travelling waves (TWs) across all lines connected to the busbar are calculated using Karenbauer transformation. Thereafter, the polarity and magnitude of wavelet transform modulus maximas of line current appearing after fault inception are analysed for fault zone and faulty phase identification. Its performance has been evaluated by modelling an existing 750 kV Indian substation in PSCAD/EMTDC software package. The simulation results reveal that the proposed scheme provides better stability for external faults and higher reliability in case of internal faults in comparison with conventional low-impedance busbar differential protection scheme (87B). Moreover, it remains immune to the current transformer saturation problems. In the end, comparative evaluation of the proposed scheme with the existing busbar protection schemes proves its superiority in terms of stability against external faults, sensitivity for internal faults, computational obligations, and communication requirements.

Secure transmission line distance protection during wide area cascading events using artificial intelligence

The problem of distance protection misoperation has been a research priority recently because it was a major contributing factor in blackouts around the world such the 2003 US-Canada blackout and the 2015 Turkish blackout. In this paper, we propose a method that uses local relay data to enhance the security of zone 3 distance protection for transmission lines, even during wide area cascading events. Three k-nearest neighbor classifiers are trained using the details coefficients of discrete wavelet transform of the aerial mode currents without using any voltage signals altogether. The first classifier determines whether a fault has occurred. The second and third classifiers collectively determine whether this fault is within the zone 3 reach of the relay. If the second and third classifiers determine that the fault is outside the zone 3 reach of the relay, then a blocking signal will be sent to the relay to prevent operation even if the impedance falls within the operating characteristic of the relay. Alternatively, if the second and third classifiers determine that the fault is within zone 3 reach of the relay, a permissive trip signal will be sent to the relay only if the fault has not been cleared.

A new life for old laser data: the case of the Insula of the Centenary [IX, 8] in Pompeii

The survey technology with laser instruments is today more and more established and widespread even at the level of small professional teams. Hand in hand with the introduction of increasingly compact, lightweight and highly autonomous instruments, software has been developed to receive data from multiple laser sources of different manufacturers, with different acquisition formats, combining point clouds, both structured and unstructured, also coming from photographic surveys, taken in terrestrial or aerial mode (also via drones). A simplification and automation of the various data processing steps has allowed it to be used by a more general user, not strictly specialized. The article deals with the issue of the reuse of old laser scans, many years after their execution, with new software to allow a new and wider dissemination. As a case study, the one of the Insula del Centenario in Pompeii is presented.

Suggested closed-loop response characteristics for tanker in aerial refueling via mission-oriented evaluation

The flight control law design for tanker should ensure that the closed-loop response can meet the aerial refueling mission requirements. In order to reveal the movement characteristics of the tanker and the handling characteristics of the pilot in aerial refueling, the flight path capture and hold under gust disturbance task is designed as the demonstration maneuver mission to evaluate the flying qualities for tanker in aerial refueling task, which is based on the design requirements of maneuvering tasks used in mission-oriented flying qualities assessment. By analyzing the flight path tracking and holding requirements of the tanker in aerial refueling mission, the relevant parameters that reflect the response characteristics of the tanker in pitch and roll axes are put forward. The ground flight simulation test based on mission-oriented flight quality assessment is conducted, and the test pilot’s assessment results based on Cooper-Harper rating and PIO scales are obtained for different flight control law configurations. The suggested requirements of the closed-loop response characteristics of the pitch and roll axes of the tanker are put forward, which can be specifications for the aerial refueling mode flight control design of tanker.

Potential of UAV-Based Active Sensing for Monitoring Rice Leaf Nitrogen Status.

Unmanned aerial vehicle (UAV) based active canopy sensors can serve as a promising sensing solution for the estimation of crop nitrogen (N) status with great applicability and flexibility. This study was endeavored to determine the feasibility of UAV-based active sensing to monitor the leaf N status of rice (Oryza sativa L.) and to examine the transferability of handheld-based predictive models to UAV-based active sensing. In this 3-year multi-locational study, varied N-rates (0–405 kg N ha−1) field experiments were conducted using five rice varieties. Plant samples and sensing data were collected at critical growth stages for growth analysis and monitoring. The portable active canopy sensor RapidSCAN CS-45 with red, red edge, and near infrared wavebands was used in handheld mode and aerial mode on a gimbal under a multi-rotor UAV. The results showed the great potential of UAV-based active sensing for monitoring rice leaf N status. The vegetation index-based regression models were built and evaluated based on Akaike information criterion and independent validation to predict rice leaf dry matter, leaf area index, and leaf N accumulation. Vegetation indices composed of near-infrared and red edge bands (NDRE or RERVI) acquired at a 1.5 m aviation height had a good performance for the practical application. Future studies are needed on the proper operation mode and means for precision N management with this system.

Fault location in distribution network using travelling waves

PurposeAn electrical power distribution network is expected to deliver uninterrupted power supply to the customers. The disruption in power supply occurs whenever there is a fault in the system. Therefore, fast fault detection and its precise location are necessary to restore the power supply. Several techniques are proposed in the past for fault location in distribution network but they have limitations as their fault location accuracy depends on system conditions. The purpose of this paper is to present a travelling wave-based fault location method, which is fast, accurate and independent of system conditions.Design/methodology/approachThis paper proposes an effective method for fault detection, classification and location using wavelet analysis of travelling waves for a multilateral distribution network embedded with distributed generation (DG) and electric vehicle (EV) charging load. The wavelet energy entropy (WEE) is used for fault detection and classification purpose, and wavelet modulus maxima (WMM) of aerial mode component is used for faulted lateral identification and exact fault location.FindingsThe proposed method effectively detects and classifies the faults, and accurately determines the exact fault location in a multilateral distribution network. It is also found that the proposed method is robust and its accuracy is not affected by the presence of distributed generation and electric vehicle charging load in the system.Originality/valueTravelling wave based method for fault location is implemented for a multilateral distribution network containing distributed generation and electric vehicle load. For the first time, a fault location method is tested in the presence of EV charging load in distribution network.

An Effective Ground Fault Location Scheme Using Unsynchronized Data for Multi-Terminal Lines

Traveling-wave-based methods perform poorly for the fault location of multi-terminal lines as a result of the limitation introduced by being a highly branched structure. The requirement for multi-terminal time synchronization is also a drawback and needs to be improved. In this paper, an effective fault location method for use on multi-terminal lines is proposed, and it does not require the data from each terminal to be synchronized. The method is based on the arrival time differences in the ground and aerial mode waves detected at each terminal. First, fault section identification rules for a three-terminal line are proposed. Then, a multi-terminal topological structure in this paper will be deemed as one consisting of multiple three-terminal lines. Thus, a whole scheme to identify any fault section in a multi-terminal line is presented. Consequently, the fault distance is calculated using the fault distance ratios in the corresponding fault section. The advantage of the proposed scheme is that complete coverage of multi-terminal lines fault location can still be achieved once some synchronized devices are out of operation. To evaluate the performance of the proposed method, many fault cases under different conditions are implemented. The simulation results show that the proposed method can identify the fault section correctly and locate the fault more accurately and reliably than existing methods.

A LIGHTWEIGHT UAV-BASED LASER SCANNING SYSTEM FOR FOREST APPLICATION

Abstract Lightweight Unmanned Aerial Vehicles (UAVs) have become a cost effective alternative for studies which use aerial Remote Sensing with high temporal frequency requirements for small areas. Laser scanner devices are widely used for rapid tridimensional data acquisition, mainly as a complementary data source to photogrammetric surveying. Recent studies using laser scanner systems onboard UAVs for forestry inventory and mapping applications have presented encouraging results. This work describes the development and accuracy assessment of a low cost mapping platform composed by an Ibeo Lux scanner, a GNSS (Global Navigation Satellite System) antenna, an Inertial Navigation System Novatel Span-IGM-S1, integrating a GNSS receiver and an IMU (Inertial Measurement Unit), a Raspberry PI portable computer and an octopter UAV. The system was assessed in aerial mode using an UAV octopter developed by SensorMap Company. The resulting point density in a plot with trees concentration was also evaluated. The point density of this device is lower than conventional Airborne Laser Systems but the results showed that altimetric accuracy with this system is around 30 cm, which is acceptable for forest applications. The main advantages of this system are their low weight and low cost, which make it attractive for several applications.

A Novel Busbar Protection Based on the Average Product of Fault Components

This paper proposes an original busbar protection method, based on the characteristics of the fault components. The method firstly extracts the fault components of the current and voltage after the occurrence of a fault, secondly it uses a novel phase-mode transformation array to obtain the aerial mode components, and lastly, it obtains the sign of the average product of the aerial mode voltage and current. For a fault on the busbar, the average products that are detected on all of the lines that are linked to the faulted busbar are all positive within a specific duration of the post-fault. However, for a fault at any one of these lines, the average product that has been detected on the faulted line is negative, while those on the non-faulted lines are positive. On the basis of the characteristic difference that is mentioned above, the identification criterion of the fault direction is established. Through comparing the fault directions on all of the lines, the busbar protection can quickly discriminate between an internal fault and an external fault. By utilizing the PSCAD/EMTDC software (4.6.0.0, Manitoba HVDC Research Centre, Winnipeg, MB, Canada), a typical 500 kV busbar model, with one and a half circuit breakers configuration, was constructed. The simulation results show that the proposed busbar protection has a good adjustability, high reliability, and rapid operation speed.

Ultrafast Transmission Line Fault Detection Using a DWT-Based ANN

Digital impedance protection of transmission lines suffers from known shortcomings not only as a principle but also as an application. This necessitates developing a new relaying principle that overcomes those shortcomings. Such a principle is offered in this paper and is currently being validated using field data. The principle is a new application of wavelet-based artificial neural networks (ANNs). The application uses high-frequency content of a subset of local currents of one end of a protected line to classify transients on the line protected and its adjacent lines. The scheme can classify transients—including faults—occurring on a protected line, categorize transients on adjacent lines, and pinpoint the line causing the transient event. It is shown that the feature vector of the event can be determined from a subset of local currents without using any voltages altogether. The subset of local currents consists of the two aerial modes of the local current. Modal transformation is used to transform phase currents to modal quantities. Discrete wavelet transform (DWT) is used to extract high-frequency components of the two aerial modal currents. A feature vector is built using the wavelets details coefficients of one level of the aerial modes and is used to train an ANN. Results show that the classes corres-ponding to each transient event type on the protected line and its adjacent lines are almost linearly separable from each other. Results demonstrate that very accurate classification using one-eighth of a cycle of postevent data is possible.

Parameterless earth fault locator algorithm based on transient surges resulting from single-pole breaker opening

Abstract This paper proposes a novel concept for ground faults locating on the basis of the traveling waves principles for EHV transmission systems. The transient surges generated due to single-pole breaker opening are localized in order to determine the accurate fault distance on the basis of single-end measurements. The proposed fault location concept is independent of the propagation speed. Also, the proposed strategy of creating traveling surges is exploited with synchronized double-end measurements. Time extraction of traveling surges is performed using the second derivative of the aerial mode voltage after breaker pole opening. The proposed algorithm is evaluated using transmission systems of multiple terminals. The results provide evidence the efficacy of the proposed fault location mechanism.

An Approach for Detecting and Locating Evolving Faults on Transmission Lines Based on Transient Traveling Waves

There has not been a satisfactory solution to identifying and locating evolving faults on transmission lines until now. This paper presents an integrated detection and location approach for evolving faults based on transient traveling waves. Evolving faults include two sequential faults, resulting in the change of fault phase. The feature aerial mode of captured current traveling wave only reflects the feature of the second fault occurrence, and is used for analyzing the second fault. By combining traveling wave and transient energy features, fault phase selection can be implemented at two stages: the initial fault occurrence, and the short period before fault clearance. The evolving faults can be determined according to the consistency of the two-stage phase-selection results. Subsequently, the positions of the two successive faults can be precisely acquired by individually implementing the double-ended traveling wave fault location on the initial fault phase as well as the feature aerial mode currents, respectively. Digital simulation studies based on the simulation software PSCAD/EMTDC demonstrate that the proposed method is feasible and effective.

A single-phase earth fault location scheme for distribution feeder on the basis of the difference of zero mode traveling waves

Summary To eliminate the effect of line structure and unbalanced loads on the location of single-phase earth fault in distribution network, a new fault location method is proposed. In this method, the difference of the 2 zero mode traveling waves is taken as the criterion via injecting high voltage pulses into fault phase and nonfault phase, respectively. Through analyzing the transient response characteristic of distribution transformer and the propagation equation of traveling wave at the fault point, it is theoretically proved that the first difference of the 2 zero mode traveling waves is rooted in the reflection of the twice different incident wave of aerial mode voltage at the fault point, and further the fault location formula is obtained. The PSCAD-based simulation results show that the proposed method is effective and accurate to estimate fault distance. Also it has an excellent precision within certain extent.

Industry Monitoring Robot using Arduino Uno with Matlab Interface

In industries, measuring the parameters of machines is still a tedious process which is carried out by some human personnel. This paper mainly focuses on the remedial measures made to reduce human interaction with machines by using Industrial monitoring robot. This robot is hanged over the ropes to measure the parameters of machines in aerial mode. During its travel, the robot collects the parameters from the machines and transmits to control room using ZIG-BEE protocol. The control room interface with the robot is designed using MATLAB GUI model. MATLAB GUI interface shows the parameter readings from the robot and plotted in graph. The robot mainly observes temperature, smoke, toxic gases, Light intensity, defect in manufacturing machines, security purposes using cameras. Any abnormal change in the parameters can be viewed in the graph and remedial measures can be made immediately without any delay, this prevents machine damage to a greater extent. This robot is also used to indicate hazardous conditions like fire, leakage of pipes etc. to the control room using buzzers.

Earth Fault Distance Estimation Using Active Traveling Waves in Energized-Compensated MV Networks

In Nordic countries, distribution networks are traditionally unearthed and increasingly compensated. For such networks, switching their neutral point to the earth is practically applied through a resistor for better selectivity functions of earth faults. In this paper, the neutral switching and, consequently, an arrival time of the aerial mode traveling wave reflected from the fault point are utilized to accurately determine the earth fault distance. A concept to create traveling waves is implemented by earthing the neutral via a controlled thyristor that provides a short period of high fault current and produces traveling waves to estimate the fault distance. Much higher transient signals are generated by earthing through an opposite charged capacitor. A capacitor-resistor divider is utilized to measure the reflected surge over a heterogeneous distribution feeder. An adaptive setting is proposed for stamping the arrival surge. The results provide evidence of the efficacy of the proposed fault distance estimation.

Wave Propagation on an Overhead Multiconductor in a High-Frequency Region

Carson's, Pollaczek's, Wise's, and Sunde's earth-return impedances of an overhead line have been examined, and errors involved in the formulas are explained. Modified Pollaczek's and Carson's/Sunde's formulas are described. Wave propagation characteristics on a multiconductor in a high-frequency region are evaluated by adopting the modified earth-return impedance and Wise's earth-return admittance. Sommerfeld-Goubau propagation in a high-frequency region, which shows transition between transverse electromagnetic and transverse magnetic propagation, has been confirmed in the calculated results which agree with those predicted by Kikuchi for a single conductor. On a multiconductor system, it is found that the aerial mode also shows Sommerfeld-Goubau propagation when the separation between conductors is large and the earth resistivity is high.

Fault location based on single terminal travelling wave analysis in radial distribution network

Fault location remains a challenging problem in order to restore power supply rapidly. In this paper, a novel single-terminal traveling wave fault location procedure is proposed in a radial distribution network. Firstly, the propagating speed of zero mode traveling wave is determined by BP neutral network method. Then the preliminary estimation of fault distance is calculated based on the difference of velocities by discriminating the accurate timestamps of initial zero and aerial mode wave fronts. With this preliminary fault distance, the exact arrival timestamps of reflected wave fronts from fault position and far terminal end can be successful yielded. Finally, depended on mathematical relation of selected pairs-timestamps, the fault distance can be calculated precisely. Simulations have performed in PSCAD/EMTDC and the results show the accuracy and validity of procedures proposed above.

Spectrum Comparative Study of Commutation Failure and Short-Circuit Fault in UHVDC Transmission System

When commutation failure occurs in UHVDC transmission system, the transient process of DC voltage and current are similar to grounding short-circuit fault. In order to differentiate them effectively, the paper introduces mathematical morphology methods to analysis the spectrum of transient current. Base on Yunnan-Guangzhou kV UHVDC transmission system, the paper simulates the commutation failure and DC line short-circuit fault under different fault conditions in PSCAD/EMTDC. By modified morphology filter, the transient signal of DC () is decomposed into six scales, and morphological characteristics of aerial mode component of is analyzed under different scales. The simulation results show that when DC line short-circuit faults occurs, wherever in the rectifier side, in the DC transmission line midpoint or in the inverter side, the aerial mode component of have more high frequency weight in ~ and decays gradually; When commutation failures, which are caused by the inverter side AC system single-phase grounding fault, phase to phase fault, three phase grounding fault or the inverter side transformer ratio increased, the aerial mode component of have less frequency weight in.

A Single-End Method for Fault Section Estimation in Distribution Network Using Wavelets

The paper presents a method for identify fault section in distribution network, which uses the traveling wave data recorded at the substation only. After modal transformation, the aerial mode component is in stable velocity and low attenuation and utilized in the method. Compared to the first wave head, subsequent wave heads of aerial mode component have some particular characteristics with time delay and wavelet transform modulus maxima (WTMM) ratio. The number of characteristic wave heads (CWHs) which are judged by characteristic time delays (CTDs) is the criteria to identify the fault section. The simulation results verify that the method has high accuracy.