This paper investigates the converting feasibility of low voltage alternating current (LVAC) networks into low voltage direct current (LVDC) counterpart. Addressing the insertion of distributed energy resources (DER) ...
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ISBN:
(纸本)9781665485371
This paper investigates the converting feasibility of low voltage alternating current (LVAC) networks into low voltage direct current (LVDC) counterpart. Addressing the insertion of distributed energy resources (DER) in the grid, in terms of electrical losses and power capacity, the work proposes a methodology supported by computational simulation aiming at the increase of the system efficiency. The study is conducted on a low voltage European residential network model, where the conventional LVAC and an equivalent LVDC topologies are confronted. Based on several scenarios, with and without the presence of DER in different penetration levels and also considering unbalanced loads, the DC configuration demonstrates to be an adequate interface for the insertion of DER, reducing losses and facilitating the integration of new resources. Corroborating with the well-known benefits assigned to the high voltage direct current systems (HVDC), the relevance of the investigation can be highlighted by the advantages observed also in low voltage level.
Distributed generation (DG) and other electric resources such as batteries and electric vehicles are transforming the planning and operation of power distributionsystem all over the world. Although the operation gets...
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Distributed generation (DG) and other electric resources such as batteries and electric vehicles are transforming the planning and operation of power distributionsystem all over the world. Although the operation gets more complex in the presence of DG, it also brings some potential benefits to the grid. In this study, the authors propose an optimisation approach for multiple DG units scheduling, considering a daily load profile. The main objective is to minimise the total energy loss in a period of time, dealing with a specific voltage and unbalance constraints, required by the Brazilian Electricity Regulatory Agency. The problem formulation results in a discontinuous non-convex objective function. An empirical continuous metaheuristic (ECM) is proposed to solve this challenging optimisation problem. As metaheuristic methods are suitable for this kind of problems, they present some limitations regarding final results variability, relative dependence on initial conditions and usually a large set of parameters to tune. ECM confronts directly these limitations, presenting good quality results in comparison to other well-known algorithms. By using the open distribution system simulator - openDSS, and the well-known IEEE-123 distributionsystem, the proposed approach shows its effectiveness and efficiency to optimise the grid operation, with special attention to the Brazilian requirements for unbalance.
Estimation of energy savings in distribution network through smart grid-enabled conservation of voltage reduction (CVR) approach has been investigated in this study. To achieve higher-energy savings, CVR operation has...
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Estimation of energy savings in distribution network through smart grid-enabled conservation of voltage reduction (CVR) approach has been investigated in this study. To achieve higher-energy savings, CVR operation has been carried out with deeper voltage reduction in association with photovoltaic (PV) system while keeping the node voltages within acceptable limits. The additional reactive power support has been injected by PV inverters. The injected reactive power has been controlled by droop characteristics method. Besides, the moving cloud transient effect has been incorporated in PV power output. To evaluate the energy savings, the volt-VAR control operation has been carried out in three different modes such as without CVR, only CVR, and CVR with PV system on the modified unbalanced IEEE 123 node test system. The test system and control algorithms have been developed and simulated in open distribution system simulator interfaced with MATLAB. From simulation results, it has been demonstrated that higher-energy savings and peak load demand reduction can be achieved through smart grid-enabled CVR and PV system in comparison with the only CVR with proper voltage regulation.
Power distributionsystems may have photovoltaic resources, and these resources may interface with the AC system via pulse-width modulated inverters. The pulse-width modulated currents have high-frequency spectra due ...
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Power distributionsystems may have photovoltaic resources, and these resources may interface with the AC system via pulse-width modulated inverters. The pulse-width modulated currents have high-frequency spectra due to the switching frequency, which is typically 2.0-20kHz. These carrier frequency components are asynchronous to the power frequency (the baseband, which is 50 or 60Hz). Residential photovoltaic resources are in the 2-5 kW range, and utility-scale photovoltaic resources may be in the range of 500 kW. The pulse-width modulated carrier frequency components of voltage and current propagate in the power distributionsystem, and the details of this propagation are described. Note that the pulse-width modulated voltages are not harmonics of the 60-Hz baseband frequency, nor are the several pulse-width modulated voltages generally synchronous with each other. The objective is to describe an analytical approach for the assessment of carrier frequency spectra in distributionsystems with photovoltaic resources. Analysis tools and experience with those tools are given. Information is given to distribution engineers faced with systems with pulse-width modulated inverter resources and advice on frequency ranges of study, potential modeling inaccuracies, and software tools. The results of a study on an actual high penetration solar photovoltaic feeder are given.
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