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Optimal Placement of Distributed Generation on
Distribution Networks
Distribution Networks
ABSTRACT
In this paper we evaluate a heuristic methodology to obtain the optimal placement and size of distributed generation in order to minimize the distribution utility's cost. Technical aspects like energy losses and voltage levels are considered, as well as economic aspects like price of energy, investment and operating cost of distributed generation and cost of losses. We use the IEEE 13 nodes test feeder.
INTRODUCTION
COMPETITIVE power market development is based on free and non-discriminatory access to networks for both generators and consumers. This can be achieved through well defined rules for injecting or withdrawing power from the network at specific locations and strict control of its application. Contracts should establish fair tariffs for reimbursing transmission use ,and guarantying adequate network infrastructure expansion. Power market growth and accelerated technical progress have led to plant's size and unitary capacity cost reductions. This trend has led to new investments in generation with private participation. Environmentally-friendly renewable energy technologies and cleaner fossil fuel technologies are driving the demand for distributed energy generation .Final users will be able to deliver energy on their own and to supply energy to the grid at low voltages. Energy reliability and security will be improved and electricity losses will be reduced. Distributed Generation (DG) is associated with the use of small generation units located close to or in the load centers. DG can be implemented either by the end users, by project developers, or by distribution utilities. Final consumers get an alternative supply for peak consumption or a back up option. Project developers have a business opportunity in the energy market. Distribution utilities see it as an interesting option to reduce losses, to deal with the high cost of not supplied energy, or to avoid or delay network expansion. There are several factors that must be taken into account in the planning process of expanding distribution system with DG: the number and capacity of DG units, best locations and technology, the network connection, capacity of existing system, protection schemes, among others. Installation of DG at non-optimal places can result in an increase in system losses, reconfiguration of protection scheme, voltage problems, etc., implying in an increase in costs and, therefore, having an effect opposite to the desired. For that reason, different methodologies and tools have been developed to identify optimal places to install DG capacity. These methodologies are based on optimization programs or heuristic techniques. Technical restrictions that evaluate several aspects like losses, reliability, voltage levels, protection schemes, among others, are included. In this paper we evaluate a proposed heuristic methodology in a widely used IEEE 13 nodes test feeder, to obtain the optimal placement and size of DG in order to minimize the distribution utility's cost. Technical aspects like energy losses and voltage levels were considered, as well as economic aspects like price of energy, investment and operating cost of DG and cost of losses, among others. Some changes and assumptions to the proposed methodology are listed in each section.
