OPTIMAL PLANNINGAND OPERATION OF DISTRIBUTED GENERATION IN DISTRIBUTION NETWORKS

Abstract

Distribution system planning, design and operationis facing a major change in paradigm due to deregulation of the power industry and advancements in DG technologies. Proper planning is the key to determine the best expansion strategies to provide reliable and economic services to the customer. In classical planning, the load growth typically is met by adding a new substation or upgrading the existing substation capacity along with the primary distribution feeders. Today, the rapid advances in DG technology and their numerous benefits have made them an attractive alternative to the distribution companies in their planning tasks. A mixed integer non-linear model for implementing DG (micro-turbine) as an attractive option in distribution system planning was able to find out the optimal DG capacity and location to serve the forecasted peak demand. The aim of the model is to reduce the total planning cost and to deal with different scenarios which vary from expanding of an existing substation and adding new feeders to purchasing power from an existing intertie to meet the load demand growth. A model for Distribution Systems Planning (DSP) incorporating DG and considering load models is provided.

In order to meet the dynamic load growth in an economic manner, anew mixed integer nonlinear model for solving the multistage distribution system network planning problem including DG as an economic alternative has been developed. The model is able to deal with different scenarios. The main objective is to solve the optimal sizing, timing, and locations of MV distribution substation, feeders, transformers and DG’s simultaneously. The designed modelincludes realistic rules and data that are derived from actual distribution networks. The model takes operational constraints on equipment capacities and voltage limits together into account with logical constraints, aimed at reducing the search space.

In addition, the thesis deals with the operation of distribution networks and DG units in an economic manner. For that reason an overall precise mathematical mixed integer nonlinear model containing all control devices was developed in orderto minimize the operation cost of the overall distribution network. The proposed model is capable of dealing with all types of load models. During each load level, it is required to determine the optimal power purchased from the high voltage grid as well as the optimal power to be generated from each DG unit to satisfy the load requirement with minimum cost. In addition, the parameters of all available control devices are to be optimally determined.

Keywords:Distribution system planning, distributed generation, distribution system operation, load models, micro-turbine,mixed integer non-linear models, non-linear programming models.