State Estimation in Medium Voltage Distribution Networks using Pseudo Measurements

Abstract

Transition from fossil fuels to sustainable sources of energy like wind and solar is the need of the hour. All over the globe, plans are in motion to achieve this goal. This implies addition of new elements to the grid in the form of Distributed Energy Resources (DERs). These affect the working of distribution grids and to ensure reliable as well as safe operation, it is important to keep a track on the grid’s state regularly which is essential to a Distribution System Operator (DSO). For this very reason, Distribution System State Estimator (DSSE) has been introduced and has been a prominent topic of interest. Because of lack in observability of the network owing to unavailability of measurements and the stochastic load profiles of the distribution network, DSSE poses its own challenges. Therefore, it is necessary to validate the working of a suitable DSSE that is affected by the continuous changes in the grid. By selecting a suitable algorithm, this paper attempts to solve the observability issue by introduction of pseudo-measurements. The work in this paper comprises of sensitivity analysis of Weighted Least Squares (WLS) algorithm tested on two medium voltage networks in the Netherlands with the help of modelling from Gaia software for an Enexis network and a part of Stedin’s distribution network with limited measuring devices data available. Different types of inputs are taken to test the working of the algorithm in case of Stedin’s network and in case of Enexis network, the peak load moment of the day is tested with the available month data comparing it with the mean value. The results obtained illustrate the effectiveness of the selected algorithm for DSSE and are important for the DSOs to make critical decisions when needed for grid operation.