Introduction
Distributed Generation (DG) is the generation of electricity from many small energy sources and is located closer to the user, or customer. The purpose of using distributed generation is to improve voltage profile, voltage stability, reliability, power quality and to minimize power losses. The major issues related to distributed generation are distribution process and planning, distribution network issues, power reserve and balancing issues, power quality issues and connection with grid. Distributed Generation is a new approach in the power industry. In fact, it is so new, neither a standard definition nor a standard name for it have been agreed upon. Nevertheless, various definitions and names have been used in the literature.
Distributed Generation
Some researchers define DG by rating DG units, whereas others define DG in terms of the technology used. DG also appears under different names, depending on the country. For instance, in some parts of North America, the term Dispersed Generation is used, while in South America, Embedded Generation has been coined. Meanwhile, in Europe and some Asian countries, DG stands for Decentralized Generation.
Research
After studying and analysing several papers, T. Ackermann et al. proposed a general definition for DG, suggesting that the most appropriate definition would be “an electric power source connected directly to the distribution network or on the customer site of the meter”. However, this definition does not mention any capacity criterion or the technologies used to build and run these sources. Therefore, two additional categories are suggested in classifying as well as defining DG. The first category classifies DG based on its capacity, and the second category classifies DG based on its technology.There are different types of DGs from the constructional and technological points of view. DGs may be broadly categorized as conventional and non-conventional generators. Conventional generators include micro-turbines and natural gas turbines. The non-conventional generators include Electrochemical Devices, Storage devices and Renewable devices.Solution techniques for DG deployment can be obtained via optimization methods in order to maximize DG benefits.
Evolutionary Algorithms for DG Placement
Several optimization techniques have been presented by researchers in determining the optimal location and sizing of DG. Such optimization methods can be classified into deterministic (classical) methods such as analytical methods and heuristic (evolutionary algorithm) methods such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Artificial Bee Colony (ABC), Differential Evolutionary (DE), Modified Teaching–Learning Based Optimization (MTLBO), Modified Differential Evolutionary (MDE)algorithm etc., or into single- and multi-objective, based on the number of objectives.
Purpose of Distributed Generation
The major objective of DG placement is to minimize power losses. However, other objectives, like improvement of the voltage profile and reliability and cost minimization have also been considered.The problem of optimal placement and sizing of DG has been solved by researchers as single objective, as well as multi-objective optimization problem. Single-objective optimization problem and multi-objective optimization problems are different in the sense; the single objective optimization has only one objective function whereas multi-objective optimization has more than one objective functions.
