Obstacle Recognition and Localization Based on the Monocular Vision for Double Split Transmission Lines Inspection Robot

This paper presents a mono-camera based simultaneous obstacle recognition and distance estimation method for power transmission lines(PTLs) inspection robot to avoid obstacles on or around them. The proposed robot inspects the PTLs while moving along them between power transmission towers. For autonomous navigation, our robot recognizes obstacles and avoids a collision with them. In addition, it can stop at the ends of the PTLs by recognizing its structures, such as insulators, installed at the ends of them. In order to recognize obstacles or insulators efficiently, initially, a robust PTLs detection method based on vanishing point estimation is proposed since they are installed on or around the PTLs. Then, obstacle models with various scales are built, and multiple regions-of-interest(ROIs) according to the scales of the model are constructed along the detected PTLs. Finally, obstacles are recognized within the multiple ROIs. Because each ROI represents a corresponding scale of the obstacle model to be matched, the proposed approach can efficiently deal with scale changes and also estimate distance between the robot and the obstacle simultaneously with obstacle recognition. Experimental results not only show that the proposed method correctly recognizes obstacles but also that the distance between the robot and the obstacles is estimated efficiently.

Due to the advantages of long inspection time and good inspection effect, transmission line inspection robot has gained more attention and application. This paper proposed a transmission line obstacle detection and recognition algorithm (H-CNN) for the line inspection robot, which consists of two modules: the obstacle detection module (YN-Net) and the obstacle recognition and positioning module (M-CNN). When an obstacle is detected by the YN-Net, the M-CNN is activated to identify and locate the obstacle based on a binocular camera. To solve the problem of insufficient datasets, the M-CNN divides the neural network into a feature extraction module and a feature application module, while the feature extraction module is pretrained with the common dataset and the feature extraction module is finetuned with the dataset collected in this paper. The experimental results show that the proposed obstacle detection and recognition system can meet the real-time and accuracy requirements.

This paper describes the fault classification and detection of SVC (Static VAR Compensator) integrated differential relay based double circuit transmission line applying Discrete Wavelet Transform (DWT) approach. The SVC is placed at mid-point of circuit-I of double transmission line. The other circuit (circuit-II) remains uncompensated. The differential relay based protection scheme is used for the analysis of fault detection and classification. The process starts by extracting current signals (A, B or C-phase) from both sending and receiving end of the transmission line synchronously and processes through DWT to obtain the spectral energy (SE) at both the end of the line. The Differential Spectral Energy (DSE) of each phase current signals are obtained by SE of current measured at sending end minus SE of current measured at receiving end. This DSE value is used to register the fault pattern.

At present, the technology of line inspection robot for overhead transmission lines in China and abroad is close to the practical stage.But there are still some problems, such as electromagnetic compatibility (EMC).In this paper, based on the 220kV, 500 kV, 1000 kV and other high voltage transmission lines, the electromagnetic environment of the high voltage and high current for the robot is calculated.The data of the electric field intensity and the magnetic field intensity of the high voltage transmission lines within 0.5m are calculated.The situation of electromagnetic interference (EMI) is analyzed.Furthermore, a variety of materials and methods of electromagnetic shielding are compared, and the methods of improving the electromagnetic compatibility of the inspection on robot are proposed, which can provide reference for the EMC design of the inspection robot.

This paper presents the development of the cross differential relay. The new relay is suitable to double circuit HV transmission lines. Based on basic principle of cross differential relay, the paper introduces a percentage cross differential current elements used to improve sensitivity of cross differential relay. To improve stability of cross differential relay, voltage elements are used to distinguish between fault and open circuit condition, and phase selector elements are used to block healthy phase elements. EMTP simulations and real time digital simulator system (RTDS) tests prove that the cross differential protection is able to offer correct responses under various system and fault conditions.

The double circuit EHV transmission lines have been widely used because of its many advantages. But when faults occur, the style of fault and the operation condition are more complicated than that on the single circuit transmission line. The faults occurred on the transmission lines is mainly transient fault. The auto-reclosure is normally applied after the fault line tripped to improve the power supplies reliability and the power system safety. But if the fault is permanent and the auto-reclosure reclosed accordingly, the power system and its apparatus will suffer short circuit current again, resulting further damage of the equipment and making power system instability. Thus, it is very important to distinguish the transient and permanent fault before the tripped fault line auto-reclose. If the EHV line has shunt reactor, identification of fault nature becomes even more difficult. There are several methods proposed for distinguishing the transient and permanent fault but mainly for single circuit transmission line. In this paper, a novel method is proposed for the EHV double circuit transmission lines with shunt reactor. After tripped, the phase voltage across shunt reactor was calculated using our established transient fault line model regardless of the fault is transient or permanent. The difference between the calculated voltage and the measured voltage of the fault phase across shunt reactor was employed to identify transient or permanent fault. The amplitude ratio, i.e. the difference of the voltage between calculated and measured to the voltage across neutral reactor was used to judge fault nature. If the amplitude ratio is greater less than 1, the fault is regarded as transient. If it is more than 1, it is regarded as permanent. This result can be further verified by EMTP simulation.

By the excitation of the electromagnetic signal, double transmission line will inducing a voltage and current, thereby creating the space radiation field. Based on infinitesimal current source radiation field and by the convenience of the terminal response aspects of solving transmission line of BLT equation, the double transmission line is derived and gets the analytical solution.

This paper presents a new dual-arms robot called LineClimber, an inspection robot for transmission lines. This robot has a kind of new-type serial-parallel combination driven joint that combine parallel flexible-wire driven mode. The work mechanism of this robot is analyzed. Based on the procedure of crossing obstacles, five elemental work modes are planned. It provides new ideas for simplifying the design of robot control system.

During crossing obstacles and inspecting lines, an inspection robot for extra-high voltage power transmission lines will appear the phenomenon of jitter. This phenomenon is related not only to the external wind load but also to the flexibility of the inspection robot joint drive system. To reduce the jitter in the process of crossing the obstacle and crossing the obstacle, the PI control strategy is adopted to control the inspection robot joint drive system in this paper. The value of inertia of the inspection robot joint drive system is closely related to the inertia matrix of the dynamic equation of the inspection robot. Firstly the inertia matrix of the inspection robot is obtained by applying the Lagrange dynamics equation. Then the dynamic model of the inspection robot joint drive system is established. Through the state equation, the transfer function of motor speed to electromagnetic torque can be obtained. Furthermore, the parameters of the PI controller are designed by pole assignment strategies with the identical damping coefficients. Finally, numerical simulation results show that the jitter of the inspection robot can be reduced by designing PI controller parameters.

Power transmission through ring transmission systems

The effect of addition of nanoparticles to silicone rubber is studied in this paper in the context of soft robotic applications to transmission line maintenance. Silicone rubber and polylactic acid (PLA) are used in the fabrication of these robotic structures. Desirable characteristics for the materials making the structure are (i) Low surface charge and space charge accumulation and (ii) High tensile and tear strength. To meet these requirements, addition of nano MgO to silicone rubber is proposed and studies pertaining to surface potential variation, space charge variation and dielectric parameters are performed. It is observed that 3wt% MgO added silicone rubber shows better performance than pure silicone rubber. Further, silicone rubber/MgO nanocomposite sandwiched PLA shows least space charge at the electrodes and at the interfaces of the sandwich. Moreover, the mechanical properties are also enhanced via the addition of nano MgO. In particular, 3wt% MgO added silicone rubber shows maximum tensile and tear strength. A direct correlation between tear strength and Shore A hardness is also observed. In addition, substantial improvement in viscoelastic properties of silicone rubber is observed with the addition of nano MgO.

Energy flow bottlenecks in high voltage transmission lines known as congestions are one of the challenges facing power utilities in fast developing countries. Bottlenecks occur in selected power lines when transmission systems are operated at or beyond their transfer limits. In these cases, congestions result in preventing new power supply contracts, infeasibility in existing contracts, price spike and market power abuse. The “Superconductor Technology” in electric power transmission cables has been used as a solution to solve the problem of bottlenecks in energy transmission at high voltage underground cables and overhead lines. The increase in demand on power generation and transmission happening due to fast development and linked to the intensive usage of transmission network in certain points, which in turn, lead to often frequent congestion in getting the required power across to where it is needed. In this paper, a bottleneck in high voltage double overhead transmission line with Aluminum Conductor Steel Reinforced was modeled using conductor parameters and replaced by Gap-Type Superconductor to assess the benefit of upgrading to higher temperature superconductor and obtain higher current carrying capacity. This proved to reduce the high loading of traditional aluminum conductors and allow more power transfer over the line using superconductor within the same existing right-of-way, steel towers, insulators and fittings, thus reducing the upgrade cost of building new lines.

Performance of the conventional ground distance relaying scheme is adversely affected by different types of ground faults, such as single line-to-ground, double line-to-ground, and simultaneous open conductor and ground. This effect is more pronounced due to the considerable value of fault resistance and direction and magnitude of power flow. The work presented in this chapter addresses the aforementioned problems encountered by the conventional ground distance relaying scheme when protecting doubly fed transmission lines. Further, a new digital distance relaying scheme is proposed which compensates the errors produced by the conventional ground distance relaying scheme using local end data only. The detailed analysis of the apparent impedance as seen from the relaying point by the conventional ground distance relaying scheme and the proposed scheme during different types of ground faults is also presented in this paper. The feasibility of the proposed scheme has been tested using MATLAB/SIMULINK software. The simulation results demonstrate the effectiveness of the proposed scheme since it provides accuracy on the order of 98 %.

Transmission lines are generally subjected to faults, so it is advantageous to determine these faults as quickly as possible. This study uses an Artificial Neural Network technique to locate a fault as soon as it happens on the Doukan-Erbil of 132kv double Transmission lines network. CYME 7.1-Programming/Simulink utilized simulation to model the suggested network. A multilayer perceptron feed-forward artificial neural network with a back propagation learning algorithm is used for the intelligence locator's training, testing, assessment, and validation. Voltages and currents were applied as inputs during the neural network's training. The pre-fault and post-fault values determined the scaled values. The neural network's performance was evaluated, and tests were run. Line-to-ground faults were examined. The study demonstrates how effective, rapid, and precise this method is at locating faults. The neural network's performance was examined, and tests were run on it. The overall performance of the mean square error in the trained network execution was 0.11792 at 35 epochs. The correlation coefficient at the entire target was 0.99987 percent of an error on the Doukan-Erbil double transmission lines.

Existing resource-intensive obstacle avoidance techniques are hard to be applied on the small-size Unmanned Aerial Vehicles (UAVs) that have limited sensing and computation capacity. Therefore, it is necessary to develop an obstacle recognition and avoidance scheme which works under resource-constrained environments. To this backdrop, this paper first presents an obstacle recognition model based on monocular vision feature points. Afterwards, an obstacle recognition algorithm is put forward, whose computational complexity is low. Then, an obstacle avoidance method is proposed to regulate the obstacle-avoidance path of a UAV until it arrives its destination. To evaluate the effectiveness of the presented algorithms, we design and implement a simulation platform on Objective Modular Network Testbed in C++ (OMNeT++), and conduct a series of experiments. Experimental results show that the proposed model and algorithms can effectively guide a micro UAV to its destination using only an embedded processor and 0.5kg extra load. Even in poor communication conditions, the UAV can independently avoid obstacles and reach the destination only by acquiring the destination coordinates from the ground station.