Simplified method to assess the uncertainty degree of voltage estimation in active distribution networks

The management of future distribution networks involving distributed generation (DG), reactive compensation and/or controllable loads, requires a reliable state estimation (SE) of the system in terms of line flows and bus bar voltages. However traditional SE algorithms, adopted in transmission systems, appear hardly applicable in distribution networks because of the lack of available real time measurements with a consequent high level of uncertainty resulting in the estimations. To overcome this problem an original (non-iterative) process, allowing a preliminary assessment of the uncertainty in voltage estimation, has been developed. The method, based on a performance parameter, here defined as "variance moment", gives for a distribution system a quick and simplified evaluation of the network performance in making a SE. This process results also a good technique for optimizing the locations of voltage measurements showing a sensible reduction in the computational effort with respect to traditional methods.