DISCRETE ASCENT OPTIMAL PROGRAMMING APPLIED TO NETWORK CONFIGURATION IN ELECTRICAL DISTRIBUTION SYSTEMS B. A. Souza H. A. Ferreira H. N. Alves H. D. M. Braz Federal University of Campina Grande Brazil

Objective The approach is turned to new feeders planning or reforming. The main concern is to find adequate conductors and feeder routes. New optimal configurations are determined while considering economical constraints

The method An algorithm based on Discrete Ascent Optimal Programming (DAOP) minimizes losses by selecting adequate conductors and feeder routes

Necessary input data Value of the loads to be supplied and their position related to the substation; Substation position and its voltage level; Power factor of the feeder; Types of conductors which are available for primary feeder construction and their characteristics; Power losses cost; Primary feeder building costs per kilometer, according to the type of conductor.

Problem formulation The network configuration problem may be stated as: find the optimal sequence which loads should be supplied, so that power losses and feeder building costs are minimized.

Problem formulation Load and substation position A feasible solution 1 2 3 4 5 6 7 8 9 10 X (km) Y (km) substation 1 2 3 4 5 6 7 8 9 10 X (km) Y (km) substation

The objective function where: li = length of one feeder section (km); kci= building cost per kilometer of one feeder section according to the conductor used ($/km); ∆p = total system’s active power losses (kW); kp = cost per unit of active power loss ($/kW).

The DAOP algorithm The distances between substation and all loads is calculated; The load which is closer to substation is fully supplied; It is defined a “initial state” (radial configuration) from which many others configurations will be created and tested. From the initial state, loads are taken one by one in the sequence they are connected and the steps 5 to 8 are repeated until all loads are fully supplied;

The DAOP algorithm (cont.) The next load is taken and its value is updated, by the discrete load step previously chosen; From the actual configuration, all possible origin connections for that load (which does not destroy feeder radial nature) are evaluated; The cost of each feasible configuration is calculated, testing all available conductors to find the most economical option; From the initial state, loads are taken one by one in the sequence they are connected The most economical configuration is chosen and becomes the actual one.

Costs and conductors cable code cost description R (W/km) X (/km) 1 336.4 MCM 0.1904 0.3766 2 400.00 $/km 4/0 CAA 0.3687 0.4574 3 250.00 $/km 4 CA 1.5325 0.4705 power loss 8.00 $/kW

Applications Load quantity Load step Algorithm PDAO Genetic 10 10 kVA $4758 $4720 63 $4845 $4077 -- 2,5 kVA $4702

Conclusion An algorithm has been presented for determining optimal configurations: to plan new radial distribution feeders; to reform old radial distribution feeders. to check how efficient the route of an existent feeder (supplying loads in the best sequence to minimize power losses).

Conclusion (cont.) Currently, the algorithm is being adapted to include: costs of removal, addition and transfer parts of real feeders reach more economical configurations by reducing energy losses. maximum number of sections derived from a single bus forced urban paths are being implemented.