Impact of massive penetration of intermittent generation and energy storage devices in planning the amount of transmission system usage

The increase in the penetration levels of intermittent generators, e.g., photovoltaic generation, and of energy storage devices, e.g., batteries, in the Brazilian distribution networks significantly affect the demand provided by the distribution utility and, hence, the techniques currently employed to determine the Amount of Transmission System Usage (MUST, in Portuguese) at the connection points with the transmission system. If the contracted demand is violated and there is subcontracting or over-contracting, the distribution utility must pay inefficiency charges collected by the National System Operator (ONS, in Portuguese). The main difficulty and novelty of this new scenario in the distribution system are the highly stochastic characteristics associated with the intermittent generation and with the operation of energy storage devices installed in the medium and low voltage levels. Furthermore, the distribution company does not have previous knowledge of the number and locations of the connections of photovoltaic generators and energy storage devices that will occur in a period, mostly at the low voltage level. In this context, this work fits within the scope of strategic planning and proposes a new generic methodology composed of a linear programming model to determine the MUST to be contracted by the distribution utility at the connection points with the transmission system in scenarios with high penetration of photovoltaic generation and energy storage devices. This work copes with and properly incorporates the uncertainties present in this planning problem through scenario-based stochastic programming using information from demand projections made by the distribution utility and by the Energy Research Company (EPE, in Portuguese), photovoltaic solar power generation, and, batteries operations. The developed methodology is applied to a real Brazilian subtransmission system and Monte Carlo studies are employed to identify the system behavior and the most impacting factors of these devices¿ connections on the problem. Lastly, sensitivity analyses are performed aiming to verify the influence of the parameters currently defined by the Brazilian regulation (AU)