###### Abstract
The first method is easily adopted; however, it requires good coordination of the PV inverter set points and depends on the grid's short circuit parameters. In LV grids, especially in rural areas with overhead lines, high R/X ratios are observed. In this case, reactive power has little influence on voltage modules and creates additional losses [17]. Active power curtailment is a viable solution for this scenario; however, it results in a reduction in revenue for the DER owner. Efficient power quality and overall operational improvement of LV grids can be achieved by introducing energy storage systems, due to their flexibility in active power control [18; 19]. Studies show that voltage-dependent ESS control strategies can provide a good trade-off between power curtailment and voltage regulation [20]. Other authors propose coordinated PV and ESS control for effective voltage regulation, indicating differences between urban and rural scenarios [17]. Voltage regulation can also be achieved by deploying ESS at the distribution system operator (DSO) [21]. Some reported voltage-regulation methods propose centralized optimization and scheduling/dispatch [21; 22; 23]; others are based on local controllers [24; 20; 25; 26]. For LV systems, local methods are preferred, as they do not require a costly ICT infrastructure. In LV grids, due to the increasing share of sizeable single-phase loads, voltage unbalance also has to be addressed. Unbalance compensation may be achieved by reactive power control and optionally active power curtailment of single-phase inverters [27; 28]. Additionally, unbalanced control of ESS, PV and EV charging is proposed for unbalanced conditions [22; 24; 26; 29]. Typically in grid applications, droop control methods that allow sharing of regulation effort are applied, but these are not always efficient in distributed voltage control [16]. Dynamic voltage regulation requires control schemes similar to DSTATCOM, which utilize closed-loop voltage controllers [25; 30]. A conventional voltage-control method would include one of the above solutions. The goal of the conducted research was to identify a complete and easy-to-implement method for the overall improvement of the voltage quality in LV networks. The authors have not found a complex solution that includes dynamic voltage regulation, balancing and harmonics minimization. The novel solution proposed in this paper is an application of closed-loop voltage controllers based on local voltage measurement, with characteristics for DSATCOM devices and energy storage systems installed in LV grids. A shunt-compensation device is preferred over series compensation, as it is easier to install compared to series devices and allows for transformerless operation in LV grids. Additionally, the shunt compensator provides voltage profile improvement along the whole feeder, not only downstream of the compensating device. The contribution of this paper is the development of a control structure for the power electronic converter, which provides the interface between an energy storage and the distribution network. The designed control structure ensures universal power quality enhancement by a dynamic control of voltage at the point of coupling, as well as voltage balancing by negative sequence current injection. The novelty of the research is a method of setting active and reactive compensator current components, with respect to grid impedance parameters, allowing to minimize the current used for voltage regulation compared to other solutions such as reactive power control [14; 29] or active power dispatch [21; 22]. The paper is organized as follows. Section 2 describes the principle of the shunt compensation and minimization of compensator current, the design of converter control for voltage regulation and balancing. Section 3 shows the results of the laboratory experiment, proving the feasibility of the proposed method. In Sections 4 and 5, discussions and conclusions are presented, respectively.