Nodal load approximation in sparsely measured 4-wire electrical low-voltage grids by stochastic optimization

In this paper a new method to approximate nodal loads of a low-voltage grid using few measurements is presented. The performance is evaluated within two commonly occurring grid topologies. Highly unbalanced loads are associated to random nodes which represent the true state of the grid. Based on few line-to-neutral voltages and nodal-load measurements an objective function is evaluated and minimized by stochastic optimization using the simulated annealing algorithm. As unbalanced nodal loads produce a neutral shift, the use of a 4-wire load-flow algorithm is therefore mandatory. The accuracy of this load approximation technique, with respect to a sensitivity analysis of the optimization parameters, is presented. Possible areas of application for this method are state-estimation and future system-operators' decision supporting algorithms.