Distribution Grid Robust Operation under Forecast Uncertainties with Flexibility Estimation from Low Voltage Grids using a Monitoring and Control Equipment

Due to increased penetration of renewable resources in the distribution grid, the distribution system operator (DSO) faces increased challenges to maintain security and quality of supply. Since, a large proportion of renewables are intermittent generations, maintaining production and consumption balance of the electric system is at stake. The DSO needs to procure flexibilities not only from large resources, but also small-scale resources connected to the LV grid. Therefore, there is a need to estimate the aggregate flexibility at the secondary substation available from the LV grids. The flexibility estimation can only be achieved through monitoring of LV grid and the distributed energy resources (DERs) connected at the LV level. Moreover, the variability of intermittent resources affects the flexibility estimation methodology, and the DSO operation must be robust to the changes in generation or demand outputs. Furthermore, the up-to-date and accurate model of the LV grid is difficult to access. This paper demonstrates a methodology of estimating flexibility by sensitivity coefficients and thus, eliminating the need to have an up-to-date LV grid model. It further presents a robust optimisation based methodology for grid operation to address the impact of forecast uncertainties associated with the variable DER output. The methodologies illustrate the value of grid monitoring with a monitoring equipment. It has been validated on a real network of a Swiss DSO with several grid monitoring devices.