The RESOLvD project’s technology is being tested in the low voltage grid of a village called L’Esquirol, in the north of Catalunya. This grid is composed of two three-phase lines, deriving from two different secondary substations, SS-A and SS-B, and in each one of them there are both supply points and PV installations. The two three-phase transformers of the secondary substations are of different type: one is delta connected and the other is star connected. For this reason, and to couple their operation in ring configuration, one needed to be substituted. It should be noted that the MV/LV transformers are oversized with respect to the load of the area. This is because some years ago, the two substations had to supply also two high-load factories that have now closed.
This pilot area has undergone some other changes in order to test certain specific scenarios and use cases.
First, the two radial lines were connected through a link cable that allows to create a ring shape. To remotely control and reconfigure the grid moving borders, three fuses were substituted by motorized switchgears.
To analyze the energy exchanged between the batteries and the grid, and to evaluate the performance and efficiency of the technology, smart meters were installed at the beginning of the two feeders and in the point of common coupling the PED.
The PED and the batteries together with the measurement equipment are the main hardware of the project. The first ones were developed and provided by UPC and installed in SS-B. This location has been selected for space reasons, as it consists of a two floor-building, with an empty second floor.
The PED, Lithium-ion and Lead-acid batteries are installed on the second floor. The RTU and GW devices are located on the ground floor, so that it is a way to stablish a specific floor for the DSO assets and is also easier for the user to control the whole system. To sustain and distribute their weight over the floor, a metallic support was constructed and located under the energy storage system. The batteries and the BMS are electrically connected to the PED by a cable and the link from LV switch gear and the feeder-2 goes through the floor.
The pilot components in charge of measuring provided by ComSensus are the Phase Measurement Units (PMU) and the Power Quality Meters (PQM) that are installed on both the low voltage and on the medium voltage side. These analyze the power waveform and thus need connected voltage and current measurements inputs. The voltage and current ranges permitted by these devices needed the installation of voltage, current transformers and Rowosky sensors.
With all these technologies, the main goal is to evaluate the impact of the project in the distribution grid, mainly at LV (400 V) feeder level. To do so, a range of test are performed in the area regarding efficiency, planning and quality service. To test the efficiency of the technology in the pilot, the improvement of the energy profile in the SS and the reduction of power losses due to a better waveform quality will be studied. By using the measuring equipment both upstream and downstream the PED, the improvement in energy management will be able to be quantified.
When it comes to quality service, voltage profiles improvement, critical events prevention and island mode operation is studied in the pilot area. To do so, the PED and batteries installed in the SS will be crucial to smooth the voltage variations by exchanging power with the grid, increasing, or decreasing the voltage to compensate the consumption or generation variation. The measurement equipment will be again used to analyze the impact of these actions.