23 rd International Conference on Electricity Distribution Lyon, 15-18 June 2015 Paper 1332 CIRED 2015 1/5 DECENTRALIZED AND CENTRALIZED APPROACH IN THE ACTIVE MANAGEMENT OF DISTRIBUTION NETWORKS: A COMPARISON THROUGH BUSINESS CASES Susanna MOCCI, Nicola NATALE, Fabrizio PILO, Simona RUGGERI University of Cagliari – Italy susanna.mocci@diee.unica.it, nicola.natale@diee.unica.it, pilo@diee.unica.it, simona.ruggeri@diee.unica.it ABSTRACT In the modern distribution systems more attention is paid to operation strategies that bridge the transition of passive into active/smart network. By exploiting the active demand, the Distribution System Operator (DSO) may reduce technical barriers to renewable integration and increase the hosting capacity of the network. If suitable control strategies are available, Active Demand provides benefits to the customers, utility, and society as a whole. In the last years the authors proposed both centralized and decentralized control systems in order to increase the hosting capacity of Smart Grids. The aim of this paper is to highlight the effectiveness of the proposed control systems, by comparing the outcomes of the centralized and the distributed approach in the active management, respectively. INTRODUCTION Active management enables the DSO to maximize the use of the existing networks by taking full advantage of generator dispatch, demand side integration, and system reconfiguration in an integrated manner. All these ways to control and integrate Distributed Energy Resources (DERs) affect the system operation, but they also have a significant role even in the optimal development of the system. The coordination of Active Demand (AD), included the plug-in electric vehicles, distributed generation and distribution storage devices is essential to make the distribution system capable to offer services that increase security and quality of supply of power systems, improve energy efficiency and reduce the cost for energy [1], [2]. Different methods and tools for the active management can be applied in the distribution networks: centralized or decentralized approaches are both valid options, with different actors involved [3]. In the last years the authors proposed both centralized and decentralized control systems in order to increase the hosting capacity of Smart Grids. The main distinction is where decisions are taken: the Centralized Approach implies that a Central Processing Unit, located at HV/MV or MV/LV substation level, collects all the measurement and decides next actions; the Decentralized Approach implies that advanced controllers are installed in each LV node forming a distributed control system. In [4] a centralized DMS (Distribution Management System) for the operation of active distribution networks is developed within the framework of the ATLANTIDE project [5]-[7]. The algorithm is capable to find solutions that allow increasing the network hosting capacity and improving the efficiency of power delivery. It relieves power flow congestions at MV or LV level, improves voltage regulation and allows fast reconfiguration, by sending signals to the DER local controllers. When there are a lot of resources involved in the optimization and there is a huge amount of information to handle, the centralized control system is not a suitable solution, because it needs significant computational resources and expensive data communication infrastructure. Moreover, active management involve the participation of demand in several ways; one of them is the direct control of loads. The direct control of demand through an intermediate player, the Aggregator, permits DSO to reduce the impact on the systems of highly demanding loads (e.g., Electric Vehicles), or not predictable small generation, and can be used by DSO as a resource for active management. At LV level, decentralized control systems have the merit to allow the operation of many small customers with a reduced information flow by exploiting local information gathered from the field with intelligent meters. In [8], [9] authors proposed a Multi-Agent System (MAS) for the control of LV networks with active loads and EV, with a Master-Slave interaction that allows finding a global optimum without a direct control of each resource. The MAS operates without a centralized optimization system as well as the definition of network constraints that allow following specific DSO requests. The general structure of the control is based on autonomous agents that exchange information about the state of the system to develop strategies that enable the achievement of both local targets and global objectives. The aim of this paper is to highlight the effectiveness of the proposed control systems, by comparing through business cases the outcomes of the centralized and the distributed one, respectively. The optimization algorithms proposed allow designing valid and effective demand response program, able to analyse and meet the load needs to contribute to the voltage control of the distribution network. Application examples are presented in order to illustrate the algorithm effectiveness. The operational costs of the different control strategies are evaluated and compared.