As one step toward the future smart grid, condition monitoring is important to facilitate the reliability of grid asset operation and to save on maintenance cost [1]. Most failures of the power grid are caused by electrical insulation failure, and a key indicator of such electrical failure is the occurrence of partial discharge (PD). Therefore, one focus of condition monitoring is to detect PD, especially in the early stages, to prevent a serious power failure or outage.

An overview of state-of-the-art partial discharge analysis techniques for condition monitoring

The condition of the internal cellulosic paper and oil insulation are of concern for the performance of power transformers. Over the years, a number of methods have been developed to diagnose and monitor the degradation/aging of the transformer internal insulation system. Some of this degradation/aging can be assessed from electrical responses. Currently there are a variety of electrical-based diagnostic techniques available for insulation condition monitoring of power transformers. In most cases, the electrical signals being monitored are due to mechanical or electric changes caused by physical changes in resistivity, inductance or capacitance, moisture, contamination or aging by-products in the insulation. This paper presents a description of commonly used and modern electrical-based diagnostic techniques along with their interpretation schemes.

Electrical-Based Diagnostic Techniques for Assessing Insulation Condition in Aged Transformers

Impulse electric field measurement should satisfy some special requirements such as intensive signal amplitude, appropriate insulation, broadband response, and small size. Three types of integrated electro-optic sensors, designed and fabricated for measuring intensive impulse electric field, was implemented in this paper. The theoretical concerns and specific characteristics of these integrated electro-optic sensors were illustrated in terms of their structures and key parameters. The time domain input/output characteristic and frequency response of the sensors were examined too. Comparison of the time domain characteristics of these sensors revealed that the mono-shield sensor was more efficient than those with antennas in measurable amplitudes, which is critical for high electric field measurement in gas breakdown research. In addition, the application of the sensor in the lightning impulse experiment upon air gap not only verify the existence of streamer charge but also ensured that this sensor is expected to be widely used in transient measurement investigations such as the measurement of lightning electric field, air breakdown procedure, and maybe surface discharge.

Design and application of an integrated electro-optic sensor for intensive electric field measurement

Optical sensors for power transformer monitoring: A review

Partial discharge acoustic detection is an important monitoring tool for power transformer diagnosis, which was traditionally performed by mounting the piezoelectric transducers on the oil tank surface. The disadvantage of partial discharge acoustic detection is its low sensitivity when partial discharge occurs inside the winding, which greatly compromises the value of partial discharge acoustic detection. Fiber optic sensors that can be deployed within power transformer are expected to be a potential solution. In this research, we used a Sagnac fiber sensor system built in lab to investigate the benefits of using fiber optic sensor for partial discharge acoustic detection. Acoustic pulses were induced in oil outside the winding and in oil duct inside the winding of a single phase 50 kV transformer. Although both fiber optic sensor and piezoelectric sensor can effectively detect the acoustic pulses outside the winding, fiber optic sensor gained a much better sensitivity over piezoelectric transducer to detect the acoustic pulses originated inside the winding. We envisage that the proposed fiber sensor can be deployed in power transformers to significantly enhance the detection performance of acoustic emission induced by partial discharge.

High sensitivity detection of partial discharge acoustic emission within power transformer by sagnac fiber optic sensor

Development of a fibre-optic sensor for partial discharges in oil-filled power transformers

Lithium-sulfur batteries (LSBs) were barged to the forefront of new-generation energy storage systems thanks to their environmental friendliness, inexpensiveness and high energy density (1675 mAh/g). However, their practical application faces...

Renewable Biomass-derived Carbon-based Hosts for Lithium-Sulfur Batteries

OBJECTIVE
To elucidate the regulatory effects of salvianolic acid B (SalB) on trophoblast cells in preeclampsia (PE).


METHODS
3-(4,5-dimethylthiazol-2-yl)-2,5 diphenylte-trazolium bromide (MTT) assays were used to detect the viability of human extravillous trophoblast HTR-8/Svneo cells induced by HO following treatment with different concentrations of SalB. The levels of oxidative stress-related molecules, including superoxide dismutase, glutathione-Px and malondialdehyde were detected using corresponding kits. Cell apoptosis was detected using a Terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling (TUNEL) assay, and the expression of apoptosis-related proteins was detected using western blot analysis. In the present study, wound healing and Transwell assays were performed to measure the levels of cell invasion and migration. Western blot analysis was also used to detect the expression levels of epithelial-mesenchymal transition-related proteins. The mechanisms underlying SalB were further investigated using reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR) and western blot analysis, to determine the expression levels of matrix metallopeptidase 9 (MMP-9) and phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/protein kinase B (Akt).


RESULTS
SalB increased the activity of HTR-8/Svneo cells, inhibited oxidative damage and promoted the invasion and migration of trophoblast cells induced by HO. Furthermore, the expression levels of MMP-9 and members of the PI3K/Akt signaling pathway were significantly decreased. The pathway agonist, LY294002, and MMP-9 inhibitor, GM6001, reversed the effects of SalB on HO-induced cells.


CONCLUSIONS
SalB promoted the invasion and migration of HO-induced HTR-8/Svneo trophoblast cells by upregulating MMP-9 the PI3K/Akt signaling pathway.

Salvianolic acid B promotes the invasion and migration of HO-induced HTR-8/Svneo trophoblast cells by upregulating matrix metalloproteinase-9 the phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B pathway.

The conventional college snow and ice teaching multi-source resource intelligent management system has the problem of incomplete software resource analysis function, which leads to high CPU usage of system. A cloud platform based college snow and ice teaching multi-source resource intelligent management system is designed. Hardware part: record the state of the pins when the register is reset, account for the data bit width and storage capacity of DDR2 SDRAM memory, and optimise the data storage module; Part of the software: obtain ice and snow sports course objectives in colleges and universities, rationally organise the course organization form, optimise the intelligent management mode of teaching multi-source resources by using the cloud platform, support online browsing of various text resources, set relevant parameters to construct various random modification operations, and design the software resource analysis function with the knowledge fusion algorithm. Experimental results: The average CPU usage of the multi-source intelligent resource management system for snow and ice teaching in colleges and universities in this paper and the other two systems is 34.257%, 47.458%, 53.578%. Experimental results show that the performance of multi-source intelligent resource management system for snow and ice teaching in colleges and universities has been significantly improved after making full use of cloud platform.

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Zhao Zhiqiang

Papers

Development of a fibre-optic sensor for partial discharges in oil-filled power transformers

Renewable Biomass-derived Carbon-based Hosts for Lithium-Sulfur Batteries

Salvianolic acid B promotes the invasion and migration of HO-induced HTR-8/Svneo trophoblast cells by upregulating matrix metalloproteinase-9 the phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B pathway.

Multi-source Intelligent Management System of College Snow and Ice Teaching Based on Cloud Platform