In this paper, a method is proposed to determine the optimal allocation of D-STATCOM with Improved Quantum Brain Storm optimization (IQBSO) in distribution networks. The use of distributed energy resources (DERs) such as renewables is well-spread in distribution networks so that uncertainties increase significantly. As a result, distribution system operators (DSOs) need to deal with such uncertainties by applying Distribution Flexible AC Transmission System (D-FACT) devices to the networks. This paper proposes a method for determining the location and output variables of D-STATCOM devices of D-FACTS. A nonlinear Robust optimization is presented to handle the uncertainties. As an optimization method, this paper proposes IQBSO that is an extension of Quantum Brain Storm optimization (QBSO) in Evolutionary Computation. Also, this paper introduces hybrid code into IQBSO to enhance the solution search process. The proposed method is successfully applied to the 69-node distribution network.