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Solar power appears to be one of the most promising resources to meet the medium and long term renewable energy targets. The integration of large amounts of photovoltaic (PV) generation into distribution networks faces some limitations due to the network constraints. The PV community became well aware of these limitations in the last years. While first solutions have been pointed out mainly for large installations connected to the medium voltage network, the specificities of low voltage networks are still not fully understood. This paper aims at explaining the challenges associated to the planning and operation of low voltage network with high PV penetration. The actual impact of PV infeed is quantified on the basis of real and accurate network, load and generation data. Results from unsymmetrical load-flow computations are presented and the implementation of reactive power-based voltage control is shortly discussed. 26th European Photovoltaic Solar Energy Conference and Exhibition; 4469-4478

The project between tthe Deutsche Biomasseforschungszentrum (DBFZ) and the Karlsruhe Institute of Technology (KIT) focuses on the pr rovision of alternative fuels by thermochemical conversion. Biogenic residues and wastes which are not used yet or which could be utilised more efficiently are studied. The selection of possible feedstock was supported by a techhnical potential analysis including the competition to th he food industry. The technical suitability of raw materials for the fast pyrolysis (FP) process was of special in nterest. As a possible feedstock following types of biomass were studied: corn stover, corn cobs, biogenic floating re efuse (river Rhine and Baltic Sea), scrap wood, bark, rape s straw, sunflower straw, draff, diverse residues of flour production and hay. A process development unit (PDU) with a biomass feeding rate of 10 kg/h and a twin screw m mixer reactor was used for all experiments. It was found that different types of biomass form different char, condensate e and gas yields due to varying ash levels and lignocellulosic composition. Elemental formulas for feedstock, char, organic condensate and gas were estimated independent on t the feedstock due to similar elemental compositions. Pyrolysis gas analysis during the experiments gave information on the mass yields. A CO/CO2-ratio of 1 (i.e. wood) corresponds to organic condensate yields of about 50 wt.-%%, whereas a ratio of 0.3-0.7 (straw) corresponds to 18-32 wt. .-% respectively. Proceedings of the 20th European Biomass Conference and Exhibition, 18-22 June 2012, Milan, Italy, pp. 973-977

Building materials have played a more and more important role in saving building energy since the central government of China set higher standards and requirements for new-constructed and retrofit buildings after 2005. Glazing units, especially energy-saving units including LOW-E coated glazing units and PVB laminated glass, are utilized nation-wide. This paper employs energy simulation to analyze the energy-saving effects of different glazing units in residential buildings in the city of Guangzhou, as an example of hot-humid climate in China. It appeals that the PVB laminated glass can refuse 44 % solar radiation to enter rooms and reduce 40 % of the shading coefficient comparing to clear glass. Meanwhile, in the aspects of operation and design of the HVAC system, 28 % of cooling load, 21 % of installed capacity and 8.6 % of full-load operation time can be saved.

The pitch control system has a profound impact on the development of wind energy, and yet a delay or non-minimum phase can weaken its performance. Thus, there is a strong incentive to enhance pitch control technology in order to counteract the negative effects of unidentified delays and non-minimum phase characteristics. To reduce the complexity of the parameter-tuning process and improve the performance of the system, in this paper, we propose a novel control method for wind turbine pitch angle with time delays. Specifically, the proposed control method is state-space PIDD2, which is based on internal model control (IMC) and the open-loop system step response. Then, considering the tracking, disturbance rejection and measurement noise, the proposed controller is verified through simulations. The simulation results demonstrate that the state-space PIDD2 (SS-PIDD2) can provide a trade-off between robustness, time domain performance and measurement noise attenuation and effectively improve pitch control performance in contrast to series PID and PI control methods.

Chiller systems are used in many different applications in both the industrial and the commercial sector. They are considered major energy consumers and thus contribute a non-negligible factor to environmental pollution as well as to the overall operating cost. In addition, chillers, especially in industrial applications, are often associated with high reliability requirements, as unplanned system downtimes are usually costly. As many studies over the past decades have shown, the presence of faults can lead to significant performance degradation and thus higher energy consumption of these systems. Thus, data-driven fault detection plays an ever-increasing role in terms of energy efficient control strategies. However, labelled data to train associated algorithms are often only available to a limited extent, which consequently inhibits the broad application of such technologies. Therefore, this paper presents an approach that exploits only a small amount of labelled and large amounts of unlabelled data in the training phase in order to detect fault related anomalies. For this, the model utilizes the residual space of the data transformed through principal component analyses in conjunction with a biased support vector machine, which can be ascribed to the concept of semi-supervised learning, or more specifically, positive-unlabelled learning.

For large scale thermal energy storage at temperatures above 300°C, two-tank molten salt systems mark the current state-of-the-art as they are proven technology in parabolic trough and tower solar thermal power plants. Research is focusing on the utilization of molten salts not only as storage medium but also as heat transferring fluid (HTF) in parabolic trough plants [1]. The current two-tank concept offers serveral cost reduction possibilities. Firstly, instead of storing the hot and cold phase in two separate tanks, the salt could be stored inside a single tank to avoid a large gas volume. The separation of both phases can either be achieved by a floating insulated barrier or simply by the different densities of both phases. Secondly, a high share of the total investment costs of a molten salt storage system is caused by the molten salt itself. For the two-tank system in 50 MWel power plants, this can be as high as half of the total TES costs [2]. In the thermocline with filler concept, a large fraction of the molten salt can be substituted by a cost effective solid material, offering a significant potential for further cost reductions [3]. Finally, gaining operational experience of such systems and the ability to derive optimized operation strategies, promise an additional cost reduction potential. The “test facility for thermal energy storage in molten salts” (TESIS:store) has been set up at DLR in Cologne, Germany. An outside view of the plant can be seen in Fig. 1. The facility operates at temperatures up to 560 °C and a maximum molten salt mass flow of 4 kg/s. The storage volume has a length of 5.4 m with a total tank volume of 22 m³. The plant allows the investigation of the thermocline concept with and without filler and gaining widespread operation experience. Heat tracing along the containment walls and the piping ensures adiabatic conditions.

With the development of SoC technology in recent years, the ultra-low power WiFi System on SoC Chip has emerged. As a result, WiFi-based Wireless Sensor Networks come into use, especially used in Automatic Meter Reading. While because the nodes of Wireless Sensor Networks have limited energy supply, smaller storage capability and slower calculation ability, the current WiFi technology cannot be directly applied to WiFi-based Wireless Sensor Networks. The protocols should be upgraded and the security algorithms should be improved to meet the new requests. Firstly, this article describes the network architecture of WiFi-based WSN for AMR system and discusses the reason for using this analogous Mesh architecture. Secondly, the new Hardware architecture of WiFi-based WSN node is designed to realize the AMR system and verify the research work. The node can collect the data of power meter by WiFi and can be powered by a Lithium Battery. Thirdly, on the basis of study work of WiFi original routing protocol HWMP, a new method on improving the energy saving ability of HWMP to adapt the new features of WiFi-based WSN is proposed. And the simulation work on the new routing protocol E-HWMP has been done with NS2 and the simulation results show that the life cycle of the network has been extended to some degree.

Recently two approaches to extend the photoluminescence imaging (PLI) technique by evaluating the dynamic properties of the sample have been presented. Time-resolved photoluminescence measurements may provide calibration-free maps of the effective minority charge carrier lifetime in silicon wafers. Due to the transient measurement they minimize errors due to lateral inhomogeneities in setup or sample, which would usually contribute linearly to steady-state PLI measurements. In this work, we will focus on mechanically shuttered time-resolved photoluminescence imaging (TR-PLI), as it provides a high measurement range down to 5 μs at low hardware costs. 26th European Photovoltaic Solar Energy Conference and Exhibition; 1463-1466