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The recent deployment of distributed generation has led to a revolution in the use of distribution systems and the emergence of “smart grid” concepts. Smart grids are intended primarily as a means of facilitating the integration of renewable energy sources and of achieving greater system reliability and efficiency. Energy storage systems (ESSs) offer a number of benefits that can help utilities move toward those goals. One of those benefits is the capacity to improve the utilization of network infrastructure by means of proper load management. This paper proposes a methodology for allocating ESSs in distribution systems in order to defer system upgrades, minimize system losses, and take advantage of the arbitrage benefit. The cost and arbitrage benefit of energy storage installation are optimized with respect to system upgrade and energy losses costs. The primary goal of this research is to determine the optimal size and location of storage units to be installed, in addition to their optimal operation, so that total system costs are minimized, while system benefits are maximized. In this paper, a probabilistic load model is adopted instead of utilizing time-series based models, which provide an optimal solution that is valid only for the time-series pattern that is applied. [ABSTRACT FROM PUBLISHER]

Recent deployment of distributed generation has led to a revolution in distribution systems and the emergence of “smart grid” concepts. The smart grid mainly intends to facilitate integration of renewable energy sources and to achieve higher system reliability and efficiency. Different distributed generation types found in modern distribution systems can be classified into two main categories: intermittent- and dispatchable-based distributed generation; the latter has a unique capability of enabling successful islanding operation, thus improving system reliability. This article proposes a methodology for allocating dispatchable distributed generation units in distribution systems to economically improve system reliability. Distributed generation installation and operation costs are to be optimized against the reliability value, expressed as customers’ “willingness to pay” (WTP) to avoid power interruptions. Therefore, the main goal of this research work is to determine the optimal combination between distributed generation units to be installed and loads to be shed during all possible contingencies. A probabilistic load model is adopted to determine the optimal size of allocated distributed generation units. [ABSTRACT FROM AUTHOR]

This paper presents an adaptive grid-voltage sensor- less control scheme for inverter-based distributed generation units based on an adaptive grid-interfacing model. An adaptive grid- interfacing model is proposed to estimate, in real time, the inter- facing parameters seen by the inverter and the grid-voltage vector simultaneously. A reliable solution to the present nonlinear estimation problem is presented by combining a grid-voltage estimator with an interfacing parameter estimator in a parallel structure. Both estimators adjust the grid-interfacing model in a manner that minimizes the current error between the grid model and the actual current dynamics, which acts as a reference model. The estimated quantities are utilized within the inner high-bandwidth current control loop and the outer power controller to realize an adaptive grid-voltage sensorless interfacing scheme. Theoretical analysis and simulation results are provided to demonstrate the validity and usefulness of the proposed interfacing scheme. [ABSTRACT FROM AUTHOR]

Distributed Generation (DG) is used widely in the modern distribution systems. This paper proposes a novel functionality of the interface between DG and the utility network to mitigate the voltage flicker and to regulate the voltage at the Point of Common Coupling (PCC) in addition to its main function of controlling the power flow. A new control algorithm for the DG interface based on the Hilbert transform (HT) is presented. The HT is employed as an effective technique for tracking the voltage flicker levels in distribution systems. The mathematical simplicity of the proposed technique, compared with the commonly used algorithms in the literature, renders them competitive candidates for the on-line tracking of voltage flicker. The accurate tracking of the HT facilitates its implementation for the control of flicker mitigation devices. Simulation results are provided to verify the tracking capabilities of the HT and to evaluate the performance of the proposed DG interface for multifunction operation. [ABSTRACT FROM PUBLISHER]

Distributed Generation (DG) exists in distribution systems and is installed by either the utility or the customers. This paper proposes a novel utilization of the existing DG nonlinear interface not only to control the active power flow, but also to mitigate unbalance and harmonics, and to manage the reactive power of the system. The proposed Flexible Distributed Generation (FDG) is similar in functionality to FACTS, but works at the distribution level. Moreover, a novel ADAptive LINEar neuron (ADALINE) structure is presented. The new structure is applied to multi output (MO) systems for parameter tracking/estimation, and is called MO-ADALINE. It is dedicated to symmetrical components estimation. The control loop combines a Fuzzy Logic Controller (FLC) for voltage regulation, and a processing unit-based ADALINE to deal with unbalance, harmonics and reactive power compensation. One advantage of the proposed control system is its insensitivity to parameter variation, a necessity for distribution system applications. Simulations of the suggested FDG based control algorithm are conducted to evaluate the performance of the novel system. [ABSTRACT FROM AUTHOR]

An introduction to a special section of the journal, which is devoted to distributed generation and microgrids, is presented.