Intelligent Algorithm for Variable Scale Adaptive Feature Separation of Mechanical Composite Fault Signals

With the development of modern industry and scientific technology, production equipment plays an increasingly important role in military and industrial production, and the fault detection signal of gears and bearings state in transmission equipment becomes very important. Therefore, this paper proposes a gear-bearing composite fault signal decomposition and reconstruction method, which combines the marine predator algorithm (MPA) and variational mode decomposition (VMD) technologies. For the parameters’ selection of VMD, the optimization algorithm allows us to quickly and accurately obtain the results with the best kurtosis correlation index after signal decomposition and reconstruction. The experiments demonstrate the excellent performance of our method in the field of separation and denoising mixed gear-bearing fault signals.

Transient overvoltage characteristics in submarine cables of multi-terminal flexible HVDC transmission system

The overvoltage transient characteristics of submarine cables are one of the key technologies for submarine power transmission. This article takes the submarine cable of Zhoushan Multi-terminal Flexible HVDC Transmission Project as the research object. The MMC-HVDC simulation models at both ends of converter stations are built in PSCAD. The parameters and equivalent models of the flexible HVDC cables are determined, and the submarine DC cable operating overvoltage is calculated by using statistical methods. The simulation results show that the maximum overvoltage of the submarine cable, that is, the maximum overvoltage of the conductor to sheath, the sheath to the armour, and the armour to the ground are 400 kV, 7.27 kV and 0.45kV respectively. The maximum overvoltage when it occurs faults on grid-side or valve-side appears in the middle of the submarine cable. Maximum overvoltage of HVDC single pole grounding fault appears at the connection point of land cable and submarine cable. The simulation results and the discovery of features in this article provide reference in the design, selection, and testing of submarine power transmission equipment.

Civil Law Status of Transmission Equipment (Article 49 of the Polish Civil Code)

<p>The article provides an analysis of the civil law status of transmission equipment (devices) referred to in Article 49 of the Civil Code (transmission devices). Conducting business activity by a transmission entrepreneur in the field of utility services and waste disposal requires the use of transmission devices. These devices are located on real estate which are not owned by the entrepreneur and in a typical situation they remain permanently connected to such real estate. According to Article 49 of the Polish Civil Code, such devices do not constitute component parts of real estate if they are part of an enterprise. The assessment of the entry of transmission equipment into the composition of the enterprise and their ownership status, especially after entering the composition of the enterprise raises interpretation doubts. Determining who is the owner of transmission equipment is important because the owner of the equipment may be granted (Article 305¹ of the Civil Code) a transmission easement, which is a right related to the ownership of these devices. In this article, an attempt was made to resolve the aforementioned interpretation doubts.</p>

Risk Rating for Risk-Based Maintenance: A Case Study of Small Hydropower Plant in Nepal

Fourth generation maintenance philosophy and Quality management system 9001:2015, emphasis on the concept of risk based thinking. And it is one of the challenging part of maintenance department to adopt these philosophy by quantifying all the activities of the department. Risk rating based on reliability is one of the techniques to quantify the maintenance activities for those organizations, whose reliability of goods and services matter in the market. Hydropower sector is also among them whose reliability matters highly in consumer life standard. So this paper approaches to rate the risk of hydropower based on the reliability of components for the implementation of Risk-based maintenance. From the study of data recorded in log book of a small hydropower plant located in western part of Nepal, it was found that the overall reliability score of the plant was 0.9819, which was low as compared to other hydropower of Nepal, where turbine section of both the units of the plant found a higher risk score than other systems. Study adopted two tools i.e. Analytical Hierarchical based Fault Tree Analysis and Critical Analysis Technique to find the critical assets and Failure Mode and Effect Analysis for the rest of all to quantifying the risk in component level. The analysis shows that the cooling system as the critical asset for both the units and it contributes 72% and 64% in the reliability of the turbine section. The critical assets thus obtained was validated through the critical analysis technique. From which the risk score of cooling system found 90% in both the units. To analyze the risk in component level, Failure Mode and Effect Analysis of different sub component of critical assets was done. Among the sub-components of the cooling system, radial tube filter gets the highest risk score. Its components; cartridge, tube, and joints have the risk score of 450, 192, and 96 respectively. And from the critical analysis of the rest of the subsystems of uint-I and unit-II, components such as bearings, breaker of the transmission system, transmission equipment, excitation system and transformer of unit-I and breaker of the transmission system, transmission equipment and excitation system of unit-II are found to have higher critical score, hence, it is recommended to apply preventive activities on these components as per the manufacturer to reduce the risk that could be caused by their failure.

A Self-Powered Wearable Ultraviolet Radiation Detector Integrated with Wireless Devices Based on T-ZnO/PVDF Composite Fabric

Research on wearable devices has promoted the development of real-time ultraviolet intensity monitoring technology. This paper proposes a self-powered wearable ultraviolet radiation detector based on T-ZnO nanowires/PVDF composite fabric. The soft fabric base allows the device to attach to various muscles of the human body. Due to the piezoelectric and photoelectric properties, the devices can transform mechanical energy into electrical energy. The output closely relates to the ultraviolet intensity. Therefore, this kind of stable, flexible, and micro device can output piezoelectric voltage as both an energy source and a sensing signal on human bodies. Experiments have proved that the wearable ultraviolet detector has high sensing stability and can work on the skin. The self-powered feature allows it to integrate with wireless transmission equipment, which can upload the ultraviolet intensity data collected by the self-powered wearable ultraviolet radiation detector to the Big Data Cloud. This system will contribute to the formation of the Internet of Things.