Predictive Voltage Control for LV Distribution Grids exploiting Flexibility from Domestic Customers M. F. Simões, H. M. Costa, A. G. Madureira Centre for Power and Energy Systems INESC Technology and Science (INESC TEC) Porto, Portugal micael.f.simoes@inesctec.pt, helder.m.costa@inesctec.pt, andre.g.madureira@inesctec.pt Abstract— In order to avoid voltage problems derived from the connection of large amounts of renewable-based energy generation to distribution networks, new advanced tools need to be developed that are able to exploit the presence of Distributed Energy Resources (DER). This paper describes the approach proposed for a predictive voltage control algorithm to be used in LV distribution networks in order to make use of available flexibilities from domestic consumers via their Home Energy Management System (HEMS) and more traditional Distribution System Operator’s (DSO’s) resources, such as transformers with On-Load Tap Changer (OLTC) and storage devices. The proposed algorithm for the Low Voltage Control (LVC) is detailed in this paper. The algorithm was then tested through simulation using a representative Portuguese Low Voltage (LV) network in order to assess its performance in several future scenarios with different operating conditions. The future prospects for field-trial validation in a Portuguese smart grids pilot are also discussed. Keywords— Voltage control, storage devices, flexible loads, LV networks, predictive management I. INTRODUCTION Voltage control in distribution networks is often a concern for DSOs, particularly in situations where high levels of Renewable Energy Sources (RES) – such as solar photovoltaics (PV) – are connected directly at the end-user’s premises [1]. This phenomenon is especially registered in weak low voltage (LV) networks, that have long lines usually with low reactance / resistance (X/R) ratios, and where the injection of large amounts of renewable energy may lead to voltage rises that fall out of the range defined by the EN-50160 standard [2]. Therefore, new approaches to this problem need to be developed. Many of the solutions available in the scientific literature involve some type of optimization algorithms that aim at optimizing the use of the available resources in the LV grid. For instance, in [3], the authors present an algorithm developed for the optimization of LV grids that takes advantage of DER such as storage devices and flexible loads based on a multi-temporal Optimal Power Flow (OPF) algorithm that feeds from forecasting tools for load and renewable generation. Other similar approaches to the coordination of different DER in smart microgrids can be found in [4-5]. This makes the tools computationally complex, which in turn requires having more complex, dedicated systems in order to be able to run it (such as an Advanced Distribution Management System – ADMS – developed specifically for supporting the operation of the LV distribution system). Consequently, simpler alternative approaches are sought in order to enable efficient monitoring and control of LV distribution grids with large integration of DER, namely based on RES. In the H2020 InteGrid project [6], a new tool for voltage control designed specifically for LV networks is currently being developed – the LVC module. In the context of InteGrid, it is assumed that the presence of DER can be explored by the DSO for grid control and management purposes. These DER can be owned by the DSO, such as grid storage units, or owned by consumers willing to participate in grid operation under a contractual agreement. The proposed tool is intended to be a decision support tool, to assist the DSO in the management of the LV grid in an active way. Its aim is to identify a set of preventive control actions that can be implemented by the DSO in order to avoid foreseeable technical problems in the LV grid, such as voltage violations or branch/transformer overloads. The proposed tool is in fact an evolution of a previous algorithm developed within the FP7 SuSTAINABLE project [7]. This tool was embedded in the Distribution Transformer Controller developed by EFACEC (project partner) and demonstrated in a real LV network in the smart grids pilot (InovGrid) of Évora, Portugal. The algorithm was extensively tested and was successful in sending set-points to controllable resources (PV panels, storage devices and electric vehicle) in order to correct under and overvoltage problems. Results from the pilot trial demonstration are included in [8]. It should be emphasized that the previous version of the algorithm operated on a purely corrective base (i.e. the algorithm would react to any violation detected in the LV network only in the time step subsequent to that event). Another distinctive aspect of this new version of the algorithm is its intelligence to predict when a problem may occur (in preventive mode) and to act in advance in such a way that the event is circumvented.