C I R E D 21 st International Conference on Electricity Distribution Frankfurt, 6-9 June 2011 Paper 1252- Paper No 1252 1/4 PLANNING OF THE DISTRIBUTION NETWORK OGULIN USING OPTIMIZATION TOOL CADDIN Matija ZIDAR Tomislav CAPUDER Tomislav DRAGIĈEVIĆ University of Zagreb – Croatia University of Zagreb – Croatia University of Zagreb – Croatia matija.zidar@fer.hr tomislav.capuder@fer.hr tomislav.dragicevic@fer.hr Davor ŠKRLEC University of Zagreb – Croatia davor.skrlec@fer.hr ABSTRACT Presented paper demonstrates challenges and solutions proposed by University of Zagreb, Faculty of Electrical Engineering and Computing in the project of planning distribution control area Karlovac, specifically city Ogulin and its outskirts. Classical approaches which include predicting future load and needed grid upgrades are supported by optimization algorithm giving solutions for future distribution grid layout. Also; possibilities of the software CADDiN, developed for this purpose at the Faculty of Electrical Engineering and Computing are presented as well as problems, approximations and solutions applied in preparation of the input data. The final result is a layout of distribution grid during the period of which will give meaningful solutions to the planner at the minimal investment cost. INTRODUCTION Initial requirements for planning future distribution networks, in each distribution control area, were set by the distribution system operator with the goal of creating an universal template. In this proposal there were very few deviations from the classical method: grid topology data, history load, future load predictions etc. [1]. Since the sole future load prediction is not useful unless placed spatially, some other factors need to be taken into calculation (like future load centers, future potential distribution generation sites etc). [2, 3]. Combining all these information gives a complete picture of future load distribution and with that layout of the future grid. Literature on optimizing distribution grid layout is pretty extensive but will not be listed here. Following the current trends in the world which stipulate the usage of these type of software for network planning, University of Zagreb developed its own optimization algorithm. CADDiN (Computer Aided Design of Distribution Network) is an application for optimization and planning of distribution systems in differently structured distribution networks. The large majority of the existing planning tools are based on so called variant approach. This means a planner, based on his experience, defines possible solution for the future grid and the programming tools then analyzes, evaluates and compares proposed solutions. Optimizing distribution network, on the other hand, is a complex, non polynomial (NP hard), nonlinear problem. Finding a solution, with often conflicting goals, large number of unknown variables and significant number of technical and spatial boundaries creates a demanding optimization problem. [4] CADDiN consists of two main components; CADDiN MapModul and CADDiN Optimization module. CADDiN MapModul MapModul is AutoCAD add on for drawing, editing, data retrieval and Optimization module input data generator. It is also used for post-optimization visualization and analysis. Optimization module solves NP-hard combinatorial problem of distribution network layout. Algorithm is based on evolutionary algorithm, heuristic method which can find (sub)optimal solution in acceptable time. The algorithm output is a distribution network layout which takes into account the cost of the grid reinforcement as well as the cost of power losses and cost of power not delivered to the final consumer. So the goal function of the algorithm is minimization of all costs. To analyze all costs it is necessary to prepare an extensive amount of data. Optimization module input data are connection cost matrix, power lines cross section vector, power lines length vector and power lines material vector (Al/Cu). Since the software supports GIS data and analyses (Geographical Information System) every distribution network is created, drawn, in AutoCAD Map with network information stored in Object Data Tables related to each element. One of the features developed in the earlier stages is an addition to AutoCAD Map which simplifies separating and selecting elements using queries based on elements features. When determining connection cost CADDiN can distinguish and combine three types of links between substations: existing cable, ex-line route and corridor. Existing cables are available cable connections which satisfy planning conditions in horizon year. Planning requirements are determined by planer input and are based on the type of the problem. Most common ones are age, cross section, insulation level etc.