Overvoltage characteristics in symmetrical monopolar HB MMC-HVDC configuration comprising long cable systems

This contribution focuses on high voltage direct current (HVDC) transmission systems comprising modular multilevel converters (MMC) equipped with half-bridge (HB) submodules and analyses cable voltage stresses during various station internal as well as dc side faults. In order to examine relevant overvoltage characteristics affecting HVDC cable systems, a systematic approach to evaluate overvoltage stresses is presented and an extensive set of time-domain simulations is analysed for schemes operating in symmetrical monopolar configuration. Obtained results are relevant for considerations on insulation co-ordination of HVDC cable systems and for a comprehensive definition of high voltage testing requirements

Requirements for Power Hardware-in-the-Loop Emulation of Distribution Grid Challenges

The ongoing transition of low voltage (LV) power grids towards active systems requires novel evaluation and testing concepts, in particular for realistic testing of devices. Power Hardware-in-the-Loop (PHIL) evaluations are a promising approach for this purpose. This paper presents preliminary investigations addressing the systematic design of PHIL applications and their applicable stability mechanisms and gives a detailed review of the related work. A requirement analysis for emulation of grid situations demanding system services is given and the realization of a PHIL setup is demonstrated in a residential scenario, comprising a hybrid electrical energy storage system (HESS)

Integration of Novel Sensors and Machine Learning for Predictive Maintenance in Medium Voltage Switchgear to Enable the Energy and Mobility Revolutions

The development of renewable energies and smart mobility has profoundly impacted the future of the distribution grid. An increasing bidirectional energy flow stresses the assets of the distribution grid, especially medium voltage switchgear. This calls for improved maintenance strategies to prevent critical failures. Predictive maintenance, a maintenance strategy relying on current condition data of assets, serves as a guideline. Novel sensors covering thermal, mechanical, and partial discharge aspects of switchgear, enable continuous condition monitoring of some of the most critical assets of the distribution grid. Combined with machine learning algorithms, the demands put on the distribution grid by the energy and mobility revolutions can be handled. In this paper, we review the current state-of-the-art of all aspects of condition monitoring for medium voltage switchgear. Furthermore, we present an approach to develop a predictive maintenance system based on novel sensors and machine learning. We show how the existing medium voltage grid infrastructure can adapt these new needs on an economic scale

The effect of Pluchea Indica (L) (Beluntas) extracts on the insulin release of RIN5F cell line.

Our previous study showed that crude extract of Pluchea Indica was able to lower blood glucose levels in hypoglycaemic test on normal rats. This study is an attempt to demonstrate whether the effect was directly related to the effect on the insulin release by the pancreatic B cell. The B cell line of RIN5f of rats insulinamo were used in studying the insulin-releasing effect of sequential extractions of Pluchea Indica. The solvents used in the extraction were in the sequence of hexane, dichloromethane, ethyl acetate and methanol. Beside the sequential extractions there was a water extract of the plant. An antidiabetic drug, glibenclamide, which is known to stimulate B cells to produce insulin, was used as the positive control. The results showed that glibenclamide-treated, hexane, dichloromethane and water extract-treated groups were significantly increased the insulin release (p<0.01 and p<0.05 for all extract-treated groups). Thus the study showed that the model was able to demonstrate the stimulating effect of glibenclamide and show the effect of the plant extracts on B cells

In Vitro Anticancer Activity of Au, Ag Nanoparticles Synthesized Using Commelina Nudiflora L.Aqueous Extract Against HCT-116 Colon Cancer Cells

Recently, metal nanoparticles have been getting great medical and social interests due to their potential physico-chemical properties such as higher affinity, low molecular weight, and larger surface area. The biosynthesized gold and silver nanoparticles are spherical, triangular in shape with an average size of 24–150 nm as reported in our earlier studies. The biological properties of synthesized gold and silver nanoparticles are demonstrated in this paper. The different in vitro assays such as MTT, flow cytometry, and reverse transcription polymerase chain reaction (RTqPCR) techniques were used to evaluate the in vitro anticancer properties of synthesized metal nanoparticles. The biosynthesized gold and silver nanoparticles have shown reduced cell viability and increased cytotoxicity in HCT116 colon cancer cells with IC50 concentration of 200 and 100 μg/ml, respectively. The flow cytometry experiments revealed that the IC50 concentrations of gold and silver nanoparticle-treated cells that have significant changes were observed in the sub-G1 cell cycle phase compared with the positive control. Additionally, the relative messenger RNA (mRNA) gene expressions of HCT-116 cells were studied by RT-qPCR techniques. The pro-apoptotic genes such as PUMA (++), Caspase-3 (+), Caspase-8 (++), and Caspase9 (++) were upregulated in the treated HCT-116 cells compared with cisplatin. Overall, these findings have proved that the synthesized gold and silver nanoparticles could be potent anti-colon cancer drugs

On Verification of Designed Energy Systems Using Distributed Co Simulations

An essential part of the energy systems design procedure is simulation, since it serves as a tool for verification of the respective design. It serves the verifying of a stable operation of developed energy systems infrastructure, before it comes to the realization. As energy systems integration becomes an important part in a low carbon energy scenario in the future, the cooperation of experts specialized in various domains crucial to single aspects of the energy system is indispensable. Cosimulation, yet, enables the modelling in the familiar environment of the experts, but requires a detailed coordination of the simulation interfaces between the specific expert models. Hence, standardized interfaces are crucial to the efficient use of expert knowledge in distributed co simulations. Therefore, in the presented paper a workflow for the co simulation development of energy systems simulations, which simplifies the coordination procedure significantly by standardizing the interfaces between the models and their simulations, is introduced. The approach is exemplarily applied to the energy system design of a district comprising electricity and heat in order to show its successful performanc

N-1-Secure Dispatch Strategies of Embedded HVDC Using Optimal Power Flow

With the ongoing changes in the European electrical energy systems, redispatch measures are more often required to maintain system security. The introduction of HVDC transmission can potentially reduce necessary redispatch not only by providing additional transmission capacity but also with its inherent controllability. This work analyzes the effect of HVDC dispatch in regard to preventive and curative redispatch measures using a security constrained optimal power flow calculation. For this, a mixed ac/dc benchmark network with predefined contingencies is examined with different redispatch options for pre- and post-contingency operation. Results show, that the required redispatch measures can be reduced significantly by an adaptation of HVDC set points and even further, when post-contingency redispatch measures could be applied

Apoptotic activities of thymoquinone, an active ingredient of black seed (nigella sativa), in cervical cancer cell lines

Thymoquinone (TQ) is the main constituent of black seed (Nigella sativa, spp) essential oil which shows promising in vitro and in vivo anti-neoplastic activities in different tumor cell lines. However, to date there are only a few reports regarding the apoptotic effects of TQ on cervical cancer cells. Here, we report that TQ stimulated distinct apoptotic pathways in two human cervical cell lines, Siha and C33A. TQ markedly induced apoptosis as demonstrated by cell cycle analysis in both cell lines. More- over, quantitative PCR revealed that TQ induced apoptosis in Siha cells through p53-dependent pathway as shown by elevated level of p53-mediated apoptosis target genes, whereas apoptosis in C33A cells was mainly associated with the activation of caspase-3. These results support previous findings on TQ as a potential therapeutic agent for human cervical cancer