In this paper we consider an Active Distribution Network (ADN) that performs primary voltage control using realtime demand response via a broadcast low-rate communication signal. Additionally, the ADN owns distributed electrical energy storage. We show that it is possible to use the same broadcast signal deployed for controlling loads to manage the distributed storage. To this end, we propose an appropriate control law embedded into the distributed electrical storage controllers that reacts to the defined broadcast signal to control both active and reactive power injections. We analyze, in particular, the case where distributed electrical storage systems consist of supercapacitor banks and where the ADN uses the Grid Explicit Congestion Notification (GECN) for real-time demand response developed by the authors in a previous contribution. We estimate the energy reserve required for successfully performing voltage control depending on the characteristics of the network. The performance of the scheme is numerically evaluated on the IEEE 34-node test feeder. We further evaluate the effect of reactive versus active power control depending on the line characteristics. We find that without altering the demand-response signal, a suitably designed controller implemented in the storage devices allows them to successfully contribute to primary voltage control.