25 th International Conference on Electricity Distribution Madrid, 3-6 June 2019 Paper n° 1688 CIRED 2019 1/5 HOLISTIC COORDINATION OF SMART TECHNOLOGIES FOR EFFICIENT LV OPERATION, INCREASING HOSTING CAPACITY AND REDUCING GRID LOSSES Alena ULASENKA Luis DEL RIO ETAYO Pablo CIRUJANO Ormazabal Corp. Tech. – Spain Ormazabal Corp. Tech. – Spain Ormazabal Cotradis - Spain aul@ormazabal.com lre@ormazabal.com pcb@ormazabal.com Alvaro ORTIZ Ron BRANDL Juan MONTOYA Ormazabal Cotradis – Spain Fraunhofer IEE/DERlab e.V. – Germany Fraunhofer IEE - Germany aog@ormazabal.com ron.brandl@iee.fraunhofer.de juan.montoya@iee.fraunhofer.com ABSTRACT — This paper presents the results of investigation, performed in the SysTec laboratory of Fraunhofer IEE within the transnational access (TA) of European Research Infrastructure supporting Smart Grid (ERIGrid) project. The coordinated operation of Smart On-Load Tap Changer (OLTC) transformer and photovoltaics (PV) inverters is investigated, and the symmetric voltage control algorithm approach is proposed to increase the efficiency of control during PV generation periods. INTRODUCTION The penetration of Renewable Energy Sources (RES) and Electric Vehicles (EV) is expected to increase over the next decades. The 2018 Edition of the REN21 Renewables Global Status Report [1] reveals a global energy transition well underway with record new additions on installed renewable energy capacity, rapidly falling costs, increases in investment and advances in enabling technologies. Voltage rise is the most critical constraint for the integration of distributed generation (DG) in rural electric distribution networks. The distribution system operator (DSO) is responsible for maintaining voltage limits, however the DSO does not have direct access to the DG. A distributed and coordinated control scheme, considering the transformer substation as a hub 1 of the grid, should help the DSO to deal with the integration challenges allowing a cost-efficient integration of high shares of DG and EV. Coordinated voltage control concepts can delay grid reinforcement costs while increasing the DG hosting capacity of electric distribution networks. A lack of coordination, on the other hand, can cause the undesired operation of equipment and additional losses. The coordinated control has to maintain a high level of quality of supply while achieving economic benefits in comparison to network reinforcement. 1 Understood as “a common connection point for devices in network”. CONTROL STRATEGIES In order to cope with the voltage fluctuations promoted by DG and EV different voltage strategies can be applied depending on the body of research: The project “Aktives intelligentes Niederspannungsnetz” [2,3], has defined five control strategies depending on the used components: Conventional: Neither the majority of installed PV plants nor the local network stations are participating in voltage control in the distribution network or provide information for operational control. The only exception is the use of measurement value estimates to determine the forecast for network feeding from PV plants [4]. Active inverters: PV inverters vary their active and reactive power depending on set characteristic curves [5,6]. Smart Substation: There is the option of controlling the inverters from the local network station and process inverter measured values for use in the network control station. Active Substation: Voltage is controlled using the controllable distribution transformer with OLTC only using the measured values in the station directly. Measurement results of this system are presented in [3]. Active and Smart Substation: Voltage control using the controllable distribution transformer with OLTC and inverters. In addition, there is the option of using measured values from the inverters and the local network station in a harmonized control concept. Test results are shown in [7]. More recently, a different group of researchers have investigated the last control concept for increasing the PV hosting capacity of low voltage (LV) grids [8]. In this case, instead of a communication-based coordination between OLTC and inverters they propose a local control approach. However, another group of researchers, that have