This study was developed based on the INVADE architecture, and its main objective is to present an algorithm to manage uncertainties of consumption and production in-between the FO instructions, for complying with the required flexible services. In this case the scope is limited to congestion management requirements from the DSO, but the algorithm allows for improvements to add new functionalities. The proposed algorithm works slightly modifying the FO instructions in order to expand the use of flexibility to manage the congestion events. The study is organized first by introducing the concepts related to flexibility in an electric system and the actors that could need flexibility services. Then an overview is done of the current architecture operation and the information exchanges between the actor that require a service (in this case the DSO) and the FO, presenting this way the main concerns of this study. Then, this document presents the definitions of the flexible sources that will be used for the development of the algorithm, the methodology that will be carried out and the structure of the input information. In general terms, the study consists of developing the algorithm in python capable of simulating power flows on a network to determine the best way to allocate flexibility. The algorithm is then described together with the equations and mechanisms used for the flexibility allocation. A simple example has been made to explain the basics of its functioning. Then the definition of a base scenario is presented, describing the topology of the network, the characteristics of the lines and transformers and of those inflexible and flexible sources that are part of it. The assumptions of the grid behavior (demands, solar radiations for PV panels, and connection status of EV’s) and the FO instructions for the flexible sources are also given. Finally, the simulation is run and the results are analyzed, also describing the operation of the algorithm in a particular period for a complete understanding. The algorithm effectively uses the available flexibility to eliminate congestions on the network, limiting the loading percentages of lines and transformers to a predefined value. It also uses the available capacity on lines and transformers to apply downwards regulation and thus minimizing de differences with the FO instructions. The proposed algorithm allows for the reduction of infrastructure expansion costs and provide valuable information for promoting the use of flexible sources in a certain sector of the network.