Optimal placement of custom power devices to mitigate voltage dips in distribution networks

The paper presents an approach to optimally allocate custom power devices, as dynamic voltage restorers, in a given distribution network with the aim at reducing the expected number of voltage dips suffered by the customers. The optimization algorithm based on the paradigm of dynamic programming is able to find the best compromise between the benefits achievable by undertaking mitigation actions in the network and the total cost relevant to voltage dips, that includes the investment cost for the device, the cost paid by the customers for the damages caused by the not mitigated disturbances and for the premium quality contracts. In the paper, the expected voltage dip frequency is calculated by means of a stochastic method that combines the system fault rate with the deterministic short circuit theory. Examples derived from real cases are provided to show the effectiveness of the optimization.