This paper investigates the problem of multiple distributed generator (DG units) placement to achieve a high loss reduction in large-scale primary distribution networks. An improved analytical (IA) method is proposed in this paper. This method is based on IA expressions to calculate the optimal size of four different DG types and a methodology to identify the best location for DG allocation. A technique to get the optimal power factor is presented for DG capable of delivering real and reactive power. Moreover, loss sensitivity factor (LSF) and exhaustive load flow (ELF) methods are also introduced. IA method was tested and validated on three distribution test systems with varying sizes and complexity. Results show that IA method is effective as compared with LSF and ELF solutions. Some interesting results are also discussed in this paper.

Multiple Distributed Generator Placement in Primary Distribution Networks for Loss Reduction

In today's distribution grids the number of distributed generation (DG) units is increasing rapidly. Combined heat and power (CHP) plants and wind turbines are most often installed. Integration of these DG units into the distribution grid leads to planning as well as operational challenges. Based on the experience of a Dutch distribution system operators (DSO), this paper addresses several possibilities to handle grid planning issues. Effects on voltage control, grid protection, and fault levels are investigated and described. These aspects are illustrated with the aid of simulations on an existing distribution grid. It is demonstrated that in compact distribution grids voltage control problems and blinding of protection are not likely to occur and that false tripping and fault level have to be considered carefully.

Integration Issues of Distributed Generation in Distribution Grids

Optimal sizing and placement of distributed generation in a network system

The impending deregulated environment facing the electric utilities in the twenty first century is both a challenge and an opportunity for a variety of technologies and operating scenarios. The need to provide acceptable power quality and reliability will create a very favorable climate for the entry of distributed resources and innovative operating practices. Of all the different parts of an electric power system, customers identify closely with the distribution subsystem due to its proximity and visibility on a daily basis. Several recent developments have encouraged the entry of power generation and energy storage at the distribution level. Distributed resources (DR) is a term that encompasses both distributed generation (DG) and distributed energy storage (DS). A distributed utility will use both distributed resources and load management to achieve its goal. In addition, several compact distributed generation technologies are fast becoming economically viable. Integration of DG into an existing utility can result in several benefits. These benefits include line loss reduction, reduced environmental impacts, peak shaving, increased overall energy efficiency, relieved transmission and distribution congestion, voltage support, and deferred investments to upgrade existing generation, transmission, and distribution systems. Benefits are not limited to utility. Customers also benefit from DG in term of better quality of supply at lower cost. Among the many benefits of distributed generation is a reduced line loss. The purpose of this paper is to quantify this benefit for the simple case of a radial distribution feeder with concentrated load and distributed generator. With the introduction of DG, line loss reduction can be expected. The analysis is presented for varying locations of the distributed generator along the feeder and for varying output capacities. The results are presented in graphical form in terms of clearly-defined normalized parameters

Benefit of Distributed Generation: A Line Loss Reduction Analysis

A new approach for optimum simultaneous multi-DG distributed generation Units placement and sizing based on maximization of system loadability using HPSO (hybrid particle swarm optimization) algorithm

As the electric utility industry continues to restructure, driven both by rapidly evolving regulatory environments and by market forces, the emergence of a number of new generation technologies also profoundly influences the industry's outlook. While it is certainly true that government public policies and regulations have played a major role in the rapidly growing rate at which distributed generation is penetrating the market, it is also the case that a number of technologies have reached a development stage allowing for large-scale implementation within existing electric utility systems. At the onset of any discussion related to distributed generation, one question begs to be answered: is the fact that electric power producing facilities are distributed actually a new and revolutionary concept? Have power plants not always been located across broad expanses of land? The answer to these questions clearly is that electric power plants have always been sited all across the service territories of the utilities owning them. Hence, the opening question: as with many so-called innovations that have been put forward during the recent past, is the entire concept of distributed generation a simple semantic marketing hype or are we actually at the dawn of a new electric power generation era? We believe that a new electric power production industry is emerging, and that it will rely on a broad array of new technologies. This article sets the stage for distributed generation covering such topics as: the present power production situation; what distributed generation is; capability ratings and system interfaces; market penetration of internal combustion engine generators, fuel cells and microturbines; potential generation mix issues, network considerations including power quality, reactive power coordination, reliability and reserve margin, reliability, network redundancy, safety and accountability; public policy and regulatory impact; and standards.

P.R. MacGregor

Papers

Distributed generation: Semantic hype or the dawn of a new era?