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This paper presents a software-based adaptive dead-time compensation technique for single-phase grid-connected photovoltaic (PV) inverter system. To prevent a short circuit in the dc-link, a switching delay time is needed to be inserted in Pulse Width Modulation (PWM) signals. This causes the dead-time effect which is harmful to the system performance. To improve the mitigation of dead-time effect...
This paper describes the performance analysis of a multi-functional grid-connected photovoltaic (PV) system using power hardware-in-the-loop simulation (PHILS). An intelligent control scheme for the multi-functional grid-connected PV power generation system is proposed and verified though the power hardware-in-the-loop simulation computer simulation and the digital signal processor TMS320F2812 controller...
The objective of this paper is to present the current status and state-of-the-art of microgrid systems as well as the barriers that are being encountered for their integration to the network. The expectation about the microgrid performance is high, thus, issues related to the microgrid standards, autonomous operation, control strategies, regulatory barriers as well as its protection and islanding...
In this paper, an internet-like procedure for power management of MV electrical networks with responsive busses is presented. This procedure is based on the “token ring” internet protocol and considers a multi-level co-ordination of all active customers. It aims at reducing the complexity of distributed networks management while ensuring free customer participation in services for the grid support...
In the future, distributed generation (DG) needs to be enabled to actively participate in control of grid voltage and frequency. An efficient grid integration strategy is required to interconnect the DG to conventional power systems and to improve the power quality and reliability (PQR) as well. The main task of the interconnected system is to control and maintain frequency and voltage of the power...
The increasing presence of single-phase distributed generators and unbalanced loads in the electric power system may lead to unbalance of the three phase voltages, resulting in increased losses and heating. To decrease this voltage unbalance problem three-phase four-wire inverter-connected distributed generation units may be used. In this paper, the influence of the control strategy of three-phase...
This paper presents a voltage-power droop/frequency-reactive power boost (VPD/FQB) control scheme that allows multiple voltage source converters (VSCs) to operate in parallel in a VSC fed microgrid. Each current controlled VSC in such a microgrid has its own VPD/FQB controller that sets its current references to regulate the voltage and frequency of a common microgrid bus. By drooping the voltage...
This paper studies the performance of a single-stage, three-phase Photovoltaic (PV) system that is connected to a distribution network. The control is based on an outer voltage control loop and an inner current regulation loop. A Maximum Power Point Tracker (MPPT) based on Perturb & Observe (P&O) method is interfaced to outer voltage control loop. The outer voltage control loop is based on...
This paper aims to investigate the impacts of the grid-connected PV generation systems regarding the intermittent nature of renewable generation, and the characterization of PV generation with regard to grid code compliance. The impacts described here include effects that have traditionally been considered a potential concern by the electricity industry, covering voltage, current and power effects...
With the implementation of smarter grids, more Intelligent Electronic Devices (IEDs) is likely to comply with the IEC 61850 communication protocols in order to interact with each other seamlessly using GOOSE messages to exchange information amongst devices. In this paper, IEC 61850 messaging scheme will be proposed in one of the voltage control devices i.e. On-Load Tap Changer (OLTC) transformer to...
In a smart grid scenario, electrical networks are bound to evolve towards an internet-like model, where every node is connected each other, responsive to any signal, flexible and price-smart. A novel power management system should also ensure the customer participation in services for the grid support on the basis of network signals. The proposed methodology is a “token ring” internet-like procedure...
This paper discusses studies funded by the National Renewable Energy Laboratory (NREL) via SunPower, Inc. and the California Energy Commission (CEC), performed by New Power Technologies and Optimal Technologies that showed that high-penetrations of distribution-connected storage devices or plug-in vehicles can have adverse grid impacts due to their charging loads. Randomly-located or unmanaged additions,...
This paper discusses control and protection of power electronics interfaced distributed generation (DG) systems in a customer-driven microgrid (CDM). Particularly, the following topics will be addressed: microgrid system configurations and features, DG interfacing converter topologies and control, power flow control in grid-connected operation, islanding detection, autonomous islanding operation with...
Due to the expected growth in the interconnection of distributed generation around the world, power system operators are now faced with the challenge of looking beyond the distribution networks and consider the transmission grid when assessing the impacts of integrating large amounts of DG. This paper focuses on the analysis of the contribution that aggregated DG may provide to the voltage security...
Existing distribution networks have not been designed to accept extensive DG. The actual paradigm may change in the near future impelled by a word wide increasing of DG penetration in distribution grids. This paper presents the status and content of DG Spanish legislative documents. Fundamental considerations are first discussed, exclusively regarding the grid-interconnection requirement. This paper...
Grid interaction could cause the unreliability and instability, particularly in the presence of large scale integration of RES (renewable energy sources) in the electrical power distribution networks. Therefore, the required intelligence of power electronic system are analyzed and assessed in cases of grid interaction (grid connected, islanding and re-connecting) in this paper. The concepts of power...
In this paper, an efficient parallel flow for the design of the full power distribution network (PDN) is proposed. The analysis demonstrates the impact of the voltage regulator model in both frequency and time domain response. Based on the experimental results, it is observed that including the voltage regulator model in the PDN model increases the transient voltage drop and PDN response which need...
The increasing presence of single-phase distributed generators and unbalanced loads in the electric power system may lead to unbalance of the three-phase voltages, resulting in increased losses and heating effects. A type of voltage unbalance with a high probability in (low voltage) distribution networks is the unequal voltage magnitudes at the fundamental system frequency (under- and over-voltages)...
Distributed generators (DG), such as photovoltaic cells, are low cost, highly reliable and have electronic interfaces and reduced emissions. Even with the mentioned benefits, there are technical limits on the degree to which DG can be connected. One of these technical concerns is the islanding phenomenon. In utility practice at the present time, accidental islanding is an undesirable mode of operation...
Improvement of the power quality in the utility grid can be obtained by connecting damping power-electronic devices. Regarding the increased presence of converter-based distributed generation units in the power system, an active front end for distributed generation units is extended with a mitigating function. The effects of this mitigating function on harmonic voltage distortion and voltage dips...
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