Current Issue : January - March Volume : 2017 Issue Number : 1 Articles : 6 Articles
Many existing battery energy storage system (BESS) control schemes focus on mitigating negative\nimpacts resulting from the operation of distributed energy resources-photovoltaic facilities (DERPV).\nThese include out-of-firm conditions from reverse power flow or extreme variability in the\nservice voltage. Existing control strategies fail to consider how BESS control schemes need to operate\nin a consecutive day-to-day basis in order for them to be implemented in the field. In this\npaper, a novel energy management algorithm capable of dispatching a BESS unit upstream of a\nmulti-megawatt DER-PV is introduced. This algorithm referenced as the Master Energy Coordinator\n(MEC), accepts forecasted DER-PV generation and individual feeder load to create daily charge\nand discharge rate schedules. Logic is integrated to the cyclic discharging event to sync with the\nforecasted peak load, even when it will occur during the morning of the next day. To verify the\nMEC operation, Quasi-Static Time Series (QSTS) simulations are conducted on a 12.47 kV distribution\nfeeder model utilizing historical head-of-feeder and DER-PV analog DSCADA measurements...
A multi-rotor system (MRS), in which multiple wind turbines are placed on one tower,\nis a promising concept for super-large wind turbines at over 10 MW due to the cost and weight\nadvantages. The coherence effects on an MRS were investigated in this study. Although a wide range\nof coherences were measured so far, a decay constant of C = 12 is recommended in the IEC61400-1\nstandard. Dynamic simulations were performed for a 14-MW MRS, which consists of seven 2-MW\nturbines and includes wind models with three different coherences. Although the results show that\na larger coherence increases the output power and the collective loads due to tower base fore-aft\nbending, it reduces the differential loads due to tower-base torque and tower-top nodding. The most\nsignificant case is the fatigue damage due to tower base fore-aft bending, which was more than\ndoubled between the decay constants of C = 6 and C = 12. The present results indicate that the\ncoherence should be defined carefully in the design of large-scale MRSs because its effect on them is\nnot straightforward....
Lower temperature waste heats less than 373 K have strong potentials to supply additional energies\nbecause of their enormous quantities and ubiquity. Accordingly, reinforcement of power generations\nharvesting low temperature heats is one of the urgent tasks for the current generation in\norder to accomplish energy sustainability in the coming decades. In this study, a liquid turbine\npower generator driven by lower temperature heats below 373 K was proposed in the aim of expanding\nselectable options for harvesting low temperature waste heats less than 373 K. The proposing\nsystem was so simply that it was mainly composed of a liquid turbine, a liquid container\nwith a biphasic medium of water and an underlying water-insoluble low-boiling-point medium in\na liquid phase, a heating section for vaporization of the liquid and a cooling section for entropy\ndischarge outside the system. Assumed power generating steps via the proposing liquid turbine\npower generator were as follows: step 1: the underlying low-boiling-point medium in a liquid\nphase was vaporized, step 2: the surfacing vapor bubbles of low-boiling-point medium accompanied\nthe biphasic medium in their wakes, step 3: such high momentum flux by step 2 rotated the\nliquid turbine (i.e. power generation), step 4: the surfacing low-boiling-point medium vapor was\ngradually condensed into droplets, step 5: the low-boiling-point medium droplets were submerged\nto the underlying medium in a liquid phase. Experiments with a prototype liquid turbine\npower generator proved power generations in accordance with the assumed steps at a little higher\nthan ordinary temperature. Increasing output voltage could be obtained with an increase in the\ncooling temperature among tested ranging from 294 to 296 K in contrast to normal thermal engines.\nFurther improvements of the direct current voltage from the proposing liquid turbine power\ngenerator can be expected by means of far more vigorous multiphase flow induced by adding\nsolid powders and theoretical optimizations of heat and mass transfers....
The smart grid is a new generation of standard power distribution grid. The communication infrastructure\nis critical for the successful operation of the modern smart grids. The use of communication\ntechnologies ensures the reduction of energy consumption, optimal operation of the\nsmart grid and coordination between all smart grids� components from generation to the end users.\nThis paper presents an overview of existing communication technologies such as ZigBee,\nWLAN, cellular communication, WiMAX, Power Line Communication (PLC), their implementation\nin smart grids, advantages and disadvantages. Moreover, the paper shows comparison of communication\ninfrastructure between the legacy grid and the smart grid and smart grid communication\nstandards. The paper also presents research challenges and future trends in communication systems\nfor smart grid application....
This paper discusses the results obtained during an investigation of WWER-1000 Nuclear Power\nPlant (NPP) behavior at shutdown reactor during maintenance. For the purpose of the analysis is\nselected a plant operating state with unsealed primary circuit by removing the MCP head. The reference\nnuclear power plant is Unit 6 at Kozloduy NPP (KNPP) site. RELAP5/ MOD3.2 computer\ncode has been used to simulate the transient for WWER-1000/V320 NPP model. A model of\nWWER-1000 based on Unit 6 of KNPP has been developed for the RELAP5/MOD3.2 code at the Institute\nfor Nuclear Research and Nuclear Energy-Bulgarian Academy of Sciences (INRNE-BAS), Sofia.\nThe plant modifications performed in frame of modernization program have been taken into account\nfor the investigated conditions for the unsealed primary circuit. The most specific in this\nanalysis compared to the analyses of NPP accidents at full power is the unavailability of some important\nsafety systems. For the purpose of the present investigation two scenarios have been studied,\ninvolving a different number of safety systems with and without operator actions. The selected\ninitiating event and scenarios are used in support of analytical validation of Emergency\nOperating Procedures (EOP) at low power and they are based on the suggestions of leading KNPP\nexperts and are important in support of analytical validation of EOP at low power....
Wind power is an increasingly important alternative for obtaining energy supplies, both in large\ninterconnected power systems and in smaller hybrid systems and even in backup systems. The\ntemporal and spatial variability of the winds represent an obstacle to be overcome so that wind\nenergy can be increasingly used. The capacity factor of wind farms shows how this variability impacts\nthe operation of the plants and its value is of the order of 30% to 35%. The variability of the\nwind speed is influenced if the point of interest is on land or on sea, the shape of the surface, the\nproximity of water bodies, among other factors. The availability of wind is best described by the\nWeibull probability distribution, which has as one of its defining parameters one which is termed\nas shape parameter. This parameter is much higher as higher is the variability of the wind speed.\nThis paper studies the subtle influence of Weibull shape parameter on the optimal combination of\ncomponents in a wind diesel hybrid system, by means of computer simulations with the well\nknown software Homer. The results indicate a relatively small influence (as expected) in the studied\nsystem, which appears particularly when the cost of diesel is higher and the availability of\nwind is lower....
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