Optimal operation of a 30kW natural gas microturbine cluster

This paper discusses optimal operation strategies of a 30 kW natural gas microturbine (MT) cluster for electrical load-following applications. The cluster operation assures a good operational flexibility, but, at the same time, also the aspect of the partial-load MT characteristics, in terms of energy efficiency and pollutant emissions has to be taken into consideration. In particular, the experimental results show that the NOx and CO emissions are higher when the MT is operated below its rated capacity. Under these circumstances, the Evolutionary Algorithm has been employed in order to optimize the operation of this cluster from the point of view of the pollutant emissions and fuel consumption

Benchmarking Top-K Keyword and Top-K Document Processing with T2{}^2K2{}^2 and T2{}^2K2{}^2D2{}^2

Top-k keyword and top-k document extraction are very popular text analysis techniques. Top-k keywords and documents are often computed on-the-fly, but they exploit weighted vocabularies that are costly to build. To compare competing weighting schemes and database implementations, benchmarking is customary. To the best of our knowledge, no benchmark currently addresses these problems. Hence, in this paper, we present T${}^2$K${}^2$, a top-k keywords and documents benchmark, and its decision support-oriented evolution T${}^2$K${}^2$D${}^2$. Both benchmarks feature a real tweet dataset and queries with various complexities and selectivities. They help evaluate weighting schemes and database implementations in terms of computing performance. To illustrate our bench-marks' relevance and genericity, we successfully ran performance tests on the TF-IDF and Okapi BM25 weighting schemes, on one hand, and on different relational (Oracle, PostgreSQL) and document-oriented (MongoDB) database implementations, on the other hand

Experimental Researches Concerning the Influence of the Oxynitrocarburizing Thermochemical Treatment over the Structure and Corrosion Resistance of C40 Steel

The aim of the paper is to present the results of the experimental researches regarding the corrosion behaviour of C40 steel, thermochemical treated by oxidant nitrocarburizing at 570 °C. The thermochemical treatment was realized using an installation of oxidant nitrocarburizing. The characterization of the samples was done using laboratory equipments, in the following way: the composition of surface was determined using a RF GDS spectrometer (Jobin Yvon type), the structural analyses by X-ray diffraction (Rigaku Ultima IV) and scanning electron microscopy (MEB FEI). The evaluation of the corrosion resistance, which is the goal of this work, was done using the test method in salt fog, in the Laboratory of the Materials Engineering Department, Dacia plant

Voltage Control in Low-Voltage Grids Using Distributed Photovoltaic Converters and Centralized Devices

This paper studies the application of distributed and centralized solutions for voltage control in low voltage (LV) grids with high photovoltaic (PV) penetration. In traditional LV grids, the coordination of distributed PV converters and a centralized device would require massive investments in new communication and control infrastructures. The alternative of exploiting distributed PV converters for voltage control is discussed, showing that it can help to stabilize the voltage in the grid connection points also without coordination between them and/or with a centralized unit. The goal of this paper is to investigate how the setup of the voltage controllers inside PV inverters affects the operation of these controllers taking into account the limits for reactive power injection. In addition, the interaction of distributed PV converters with centralized devices (static var compensators and on load tap changers) is analyzed to assess whether additional benefits may come in these cases

Applications of power to gas technologies in emerging electrical systems

Abstract The energy sector is undergoing substantial changes in order to promote better efficiency, increase the use of renewable energy, reduce emissions and effectively deploy technologies to trade off costs and benefits One emerging solution is the application of the Power-to-Gas technology, which can be used for different purposes. In recent years, Power-to-Gas has been studied to understand the role it could play in the electrical system. This paper has the aims of analysing the existing literature about the Power-to-Gas technology in detail, by considering some solutions that have a direct impact on the electrical system (in particular electrolyser and CO2 production) and applications in the different sectors of the electricity value chain (i.e., generation, transmission, distribution and utilisation). This paper sets out the conceptual aspects that are necessary to include Power-to-Gas facilities in a more comprehensive analysis framework of the operation of the electrical system in various sectors. Some perspectives concerning new Power-to-Gas applications are also presented for each sector, and some promising aspects that are expected to play a relevant role in the future technical and economic evolution of electrical systems are discussed

Optimal operation of a microturbine cluster with partial-load efficiency and emission characterization

This paper discusses optimal operation strategies of a cluster of microturbines (MTs) for electrical load-following applications. Cluster operation ensures higher operational flexibility, but raises the issue of taking into account the partial- load MT characteristics, in terms of energy efficiency and pollutant emissions. In particular, from experimental results the NOx and CO emissions exhibit nonlinear and to some extent complementary trends at different partial-load levels. Hence, individual optimizations of fuel consumption and emission reduction are first carried out in this paper to show the conflicting nature of such objectives. Then, multi-objective optimization is performed to directly determine the best-known Pareto front. For this purpose, a procedure based on evolutionary programming is illustrated and applied to a practical case study. The results point out the degree of trade-off that can be sought when minimizing the local environmental impact of such distributed energy systems