Power Line Fault Research Articles

Intelligent islanding detection method for photovoltaic power system based on Adaboost algorithm

The universal islanding detection methods (IDMs) for photovoltaic (PV) power systems require manually thresholds setting. That will lead to a certain non-detection zone (NDZ). Moreover, disturbance signals injected by active detection methods may adversely affect power quality. Aiming at the above problems, this study proposes a passive intelligent IDM for parallel multi-PV system based on improved Adaptive Boosting (Adaboost) algorithm. Using Adaboost algorithm to generate classification models for islanding detection can theoretically avoid the NDZ of passive methods. The proposed method takes advantage of the electrical connection between characteristic parameters to adjust the classification model and improves the detection ability by redistributing the weight of each sub-model. Simulation results show that when adopted to a multi-PV system, the proposed method can effectively distinguish islanding operation in the NDZs of conventional passive IDMs. The method can also achieve accurate detection in the case of short-term power quality interferences, line faults and disturbance signal interference injected by active methods.

On the location of a power line fault

The paper proposes an algorithm to exclude the aperiodic components from short circuit currents. The computer-implemented algorithm allows locating a fault and a phase failure in 0.5 - 0.6 milliseconds. During this time interval, the magnetic cores of current transformers (CTs) do not reach saturation and processors receive undistorted information from the current transformers. Four measurements of instantaneous values of currents that are made in equal time intervals (sampling intervals) are sufficient to implement the algorithm. The exclusion of aperiodic components increases the accuracy of the fault location. The algorithm can also be used in the location of open-phase fault and in the digital relay protection based on the measurement of current and voltage.

Application of Norm Optimal Iterative Learning Control to Quadrotor Unmanned Aerial Vehicle for Monitoring Overhead Power System

Wind disturbances and noise severely affect Unmanned Aerial Vehicles (UAV) when monitoring and finding faults in overhead power lines. Accordingly, we propose repetitive learning as a new solution for the problem. In particular, the performance of Iterative Learning Control (ILC) that are based on optimal approaches are examined, namely (i) Gradient-based ILC and (ii) Norm Optimal ILC. When considering the repetitive nature of fault-finding tasks for electrical overhead power lines, this study develops, implements and evaluates optimal ILC algorithms for a UAV model. Moreover, we suggest attempting a learning gain variation on the standard optimal algorithms instead of heuristically selecting from the previous range. The results of both simulations and experiments of gradient-based norm optimal control reveal that the proposed ILC algorithm has not only contributed to good trajectory tracking, but also good convergence speed and the ability to cope with exogenous disturbances such as wind gusts.

The Detection Algorithm of Broken Wires in Power Lines Based on Grabcut Segmentation

Unmanned aerial vehicle (uav) has the advantage of rapid and efficient in power line fault detection. However, the background of power line image taken by uav is complex, and it is difficult to extract the foreground power line for fault detection.Aiming at this problem, we propose an algorithm based on Meanshift superpixel segmentation and Grabcut for further segmentation optimization. At the same time, the RANSAC algorithm is used for denoising to extract accurate power lines. Finally, the power lines are constrained based on their slender characteristics. Compare the width change on the same wire to detect the occurrence of strand breakage in the power line. The experimental results show that the algorithm has a good effect on the detection of broken strands in power lines.

Location Detection of Downed or Broken Power Line Fault not Touching the Ground by Hybrid AD Method

Location Detection of Downed or Broken Power Line Fault not Touching the Ground by Hybrid AD Method

Determination of Different Fault Features in Power Distribution System Based on Wavelet Transform

Nowadays, there are various signal processing methods that have been studied by many researchers in order to detect faults in power lines. From previous literature, signal processing that works based on time frequency analysis has been proven to accurately detect faults at high speed. In this study, wavelet transform is adopted to analyse fault occurrences on power line of distribution network. Three types of faults due to lightning, switching and short circuit fault were analysed based on their voltage waveform profiles. ‘Daubechies’ 4 (db4) mother wavelet and four levels decomposition were implemented to extract the features. Approximation at level 4 (A4) and detail coefficient at level 1 to 4 (D1-D4) were extracted to evaluate the energy, skewness, and kurtosis. Based on the results, lightning showed the highest energy, skewness and kurtosis compared to the short circuit and switching voltage waveform. Therefore, these features can be utilized as the new parameters for fault detection in a power system network

A consensus-based robust secondary voltage and frequency control scheme for islanded microgrids

This paper deals with the problem of designing a fully-distributed and robust secondary control scheme for voltage and frequency restoration of islanded microgrids along with real power sharing. Compared to the existing developments in this topic, the proposed multi-agent consensus-based secondary control scheme takes into account the effects of model uncertainty, parameter variation and unmodelled dynamics and thereby, offers a certain degree of robustness against all these factors. Due to virtue of the fully-distributed control configuration, each distributed generating (DG) unit in a microgrid requires only the information of its own and some of its neighbours but not of all other DG units attached to that microgrid. This helps in reducing the bandwidth requirement and cost of the underlying communication network and also causes enhanced flexibility and reliability of the overall microgrid operation. The proposed scheme counteracts any fluctuation in the terminal voltage and frequency of the DG units and also facilitates real power sharing among them at a pre-specified ratio despite the time-varying load disturbances, various power line faults, communication delays, etc. Finally, an exhaustive case study on a prototype IEEE 14-bus microgrid system containing five DG units has been accomplished to demonstrate the usefulness of the developed scheme.

Rate of change of frequency under line contingencies in high voltage electric power networks with uncertainties.

In modern electric power networks with fast evolving operational conditions, assessing the impact of contingencies is becoming more and more crucial. Contingencies of interest can be roughly classified into nodal power disturbances and line faults. Despite their higher relevance, line contingencies have been significantly less investigated analytically than nodal disturbances. The main reason for this is that nodal power disturbances are additive perturbations, while line contingencies are multiplicative perturbations, which modify the interaction graph of the network. They are, therefore, significantly more challenging to tackle analytically. Here, we assess the direct impact of a line loss by means of the maximal Rate of Change of Frequency (RoCoF) incurred by the system. We show that the RoCoF depends on the initial power flow on the removed line and on the inertia of the bus where it is measured. We further derive analytical expressions for the expectation and variance of the maximal RoCoF, in terms of the expectations and variances of the power profile in the case of power systems with power uncertainties. This gives analytical tools to identify the most critical lines in an electric power grid.

Fault Detection and Location of Broken Power Line Not Touching the Ground

Abstract Occurrences of High Impedance Faults are common in Power Distribution between substation to substation, substation to rural area and within rural area. High Impedance Faults are detected based on Fault current measured by Fault Detection devices But an important fault is the Downed or Broken power line Fault not touching the ground cannot be detected when there is not enough faults current to operate fault detection devices in Over Head power distribution. Many methods to find High Impedance Faults exist. However, no proper method exists to find the Detection and location of Downed or broken power line Fault not touching the ground .Such a condition represents no electrical abnormality and till now its detection would probably have to depend on visual sighting. This paper proposes methods F-PLCCG and Hybrid AD method going to solve above problem.

Location of Downed or Broken Power Line Fault Not Touching the Ground

Location of Downed or Broken Power Line Fault Not Touching the Ground

Повышение точности одностороннего определения места «_» *_» 1 повреждения в электрической сети произвольной конфигурации

For clearing faults in power lines, the fault location procedure (FLP) is carried out. Aunilateral FLP based on the power frequency current and voltage components is considered. The existing calculation expressions for carrying out power line FLP are often applicable only for partial network configuration cases, and attempts to apply them for other cases result yield results containing a methodical error. A general fault location algorithm in which the superposition principle is used has been developed. A technique for compensating the effect of contact impedance based on the superposition principle is considered. A calculation expression for unilateral fault location written in the phase coordinates for an arbitrarily configured electric network is derived. The results from simulation experiments and calculations carried out using real time histories of emergency events have shown that the proposed method ensures high accuracy. Recommendation sonusing the developed method are given.

Automation of calculations of power transformers windings parameters taking into account the position of the voltage regulator

We consider the issues of modeling power lines using a self-adjusting mathematical model which allows analyzing the lines operating modes while tracking instantaneous values of parameters. The obtained model can be used to build high-speed protection against phase-to-phase faults in power lines with a voltage of 10-35 kV, which have a small length.

Creation of a mathematical model to identify short circuits in power lines

We consider the issues of modeling power lines using a self-adjusting mathematical model which allows analyzing the lines operating modes while tracking instantaneous values of parameters. The obtained model can be used to build high-speed protection against phase-to-phase faults in power lines with a voltage of 10–35 kV, which have a small length.

Adaptation of power lines fault location methods to voltage characteristics deviations

The influence of voltage characteristics deviations, acceptable in normal operation of power grid, at power lines emergency state fault location methods precision is considered. The error distributions of emergency state fault location methods across power line length under frequency deviation, single rapid voltage changing and supply voltage unbalance variation are received. The way of emergency state fault location adaptation to voltage characteristics deviations is offered.

Detection of downed or Broken power line Fault not touching the ground

Detection of downed or Broken power line Fault not touching the ground

Study on the method of fault set for AC/DC system operation considering wind power

With the rapid development of power system, wind power becomes an important generating way in AC/DC hybrid power grid. Due to the interference between the wind power and the AC network, the risk of DC system continuous commutation failure will be affected. In order to evaluate this effect reasonably, a method for running out of the fault set is presented in this study. Firstly, a distribution factor is proposed to determine the power line transfer after wind power or power line fault, the line with maximum load rate is chosen as the candidate failure lines; Secondly, the η short-circuit ratio and η effective short-circuit ratio indexes of the DC system is evaluated after every fault; they are used to judge whether the cascading fault of AC system induces the transient overvoltage of the converter bus to lead to wind turbines to take off the power grid net. Thus, a cascading fault sequence of the AC system is formed, and a cascading fault set that causes the transient overvoltage of the converter bus is completed. Finally, the simulation results calculated by power system department-bonneville power administration show that when the commutation failure occurs in the DC system, the system runs out immediately, and the validity of the method is verified.

A Full-Scale Experimental Validation of Electromagnetic Time Reversal Applied to Locate Disturbances in Overhead Power Distribution Lines

Electromagnetic time reversal (EMTR) has emerged as a promising technique to locate disturbances in power grids, thanks to its location accuracy and robustness against parameters uncertainties. Furthermore, in a reflective medium, like the one of a power network, it has been shown that the method requires no more than one single observation point. In this paper, we present an experimental validation of EMTR to locate disturbances in real power networks. The validation is performed on a full-scale unenergized 677-m-long, double-circuit 10-kV overhead distribution line. The disturbance is emulated by a voltage pulse injected between one of the line conductors and the ground using a high-voltage pulse generator. The frequency spectrum of the injected voltage pulse is specified such that the originated electromagnetic transients are compatible with those of power line faults, lightning, and conducted intentional electromagnetic interferences. The transient currents generated by the emulated disturbance are measured at one end of the line, considering two different line configurations. According to the EMTR technique, the measured signals are time reversed and back injected into the system that, in our case, is a simulated model of the considered distribution line. More specifically, it is represented by a constant-parameter line model implemented within the EMTP-RV simulation environment. For both cases, the disturbance is accurately located, and the phase of the circuit at which the pulse was injected is also identified.

Location and detection of downed power line fault not touching the ground

Location and detection of downed power line fault not touching the ground

Automated Fault Recognition in Power Line Patrolling Using GSM and IoT Technology

Today's civil constructions are developed using closed wiring so detecting of fault is becoming a big task to identify and solve where the fault is being located. So a pulse-type echo ranging fault locator has been developed which is suitable for locating sustained faults on telephone and power transmission lines. A number of these instruments have been in service for several years. They have been used to locate a wide variety of power and telephone line faults with signifcant reductions in service interruptions and economies in line patrolling. Before a new circuit is energized it may be tested with the line scope to ensure that all construction grounds have been removed and that all transpositions are correct. Telephone circuits also may be tested to locate sources of mismatch which introduce transmission losses. An automated fault recognizer has been developed, which operates on the same principle and which without any human intervention records the locations of sustained or transient power line faults.

Communication Characteristics of Faulted Overhead High Voltage Power Lines at Low Radio Frequencies

This paper derives a model of high-voltage overhead power line under fault conditions at low radio frequencies. The derived model is essential for design of communication systems to reliably transfer information over high voltage power lines. In addition, the model can also benefit advanced systems for power-line fault detection and classification exploiting the phenomenon of changed conditions on faulted power line, resulting in change of low radio frequency signal propagation. The methodology used in the paper is based on the multiconductor system analysis and propagation of electromagnetic waves over the power lines. The model for the high voltage power line under normal operation is validated using actual measurements obtained on 400 kV power line. The proposed model of faulted power lines extends the validated power-line model under normal operation. Simulation results are provided for typical power line faults and typical fault locations. Results clearly indicate sensitivity of power-line frequency response on different fault types.