Collab: Francesco Bellesini, Emotion SRL & Giuseppe Raveduto, Engineering Ingegneria Informatica
Following the advent of distributed generation, the electric grid underwent an impressive change in power flows. In fact, the grid had been designed and developed based on the fact that energy had a unidirectional power flow.
Electricity had to be produced in massive power plants from which, through the high voltage (HV) network, the energy had to be transmitted into the consumption areas, where it would reach the end user, through the medium voltage (MV) network and the low voltage (LV) network.
Figure 1: Unidirectional Power Flow
Today the paradigm is totally modified: we have generation plants, mainly from renewable sources (solar and wind), distributed in the MV/LV network and, when the energy produced by these plants is higher than the energy consumed by the end users present in the local electricity network, the power flow becomes reversed and goes to the primary substations (HV/MV transformation stations).
The phenomenon of reverse power flow causes stability and safety problems in the electricity grid, like voltage rise, frequency imbalance and tripping equipment, problems that the DSO have to solve to guarantee the continuity of the energy service. To understand the complexity of this phenomenon, we must consider that it is generated mainly by intermittent and non-programmable generation plants, which are strongly influenced by atmospheric conditions, making it very difficult to predict its progression. For this reason, at the dawn of distributed generation, the most widely practiced solution was curtailment, i.e. disconnecting generation plants from renewable sources when instability occurred in the electricity grid.
Figure 2: Bidirectional Power Flow
Today, thanks to the process of digitizing the electricity grid, the reaction strategy is changing; the network is equipped with devices that allow remote monitoring and management in real time. The owners and managers of the grid collect immense amounts of data that are processed by forecasting algorithms, which provide useful information to avoid the emerging of reverse power flow. An application of this information can be found in Demand Response, a mechanism used for the time shifting of end users' consumption according to the needs of the network.
Thanks to the SOFIE project, in the Terni pilot site, we use blockchain technology and, in particular, smart contracts to enable a secure and transparent DR mechanism involving the DSO, which needs energy flexibility, the EV Fleet Managers, which provide energy flexibility by directing the electric vehicles in the areas of interest to charge and, therefore, consume energy and, finally, the Energy Retailers, which supply electricity (the DSO owns the electricity grid but does not own the energy that passes through it, which is sold by the Energy Retailers).
Figure 3: Mitigation of Reverse Power Flow by Involving EVs in DR Campaign
The DSO through a dashboard identifies the need for flexibility and creates a request within the flexibility marketplace. The Fleet Manager through a dashboard identifies the DSO request and, if it is able to satisfy the request, makes an offer in the flexibility marketplace. The DSO selects the Fleet Manager who has provided in the marketplace the offer of flexibility at the lowest price. The Fleet Manager who wins the supply of flexibility creates an energy supply request in the energy marketplace. The Energy Retailer that provided the lowest price offer in the energy marketplace wins the energy supply. The DR campaign is performed, the DSO gives the Fleet Manager tokens and the Fleet Manager gives the tokens to the Energy Retailer.
The end result is a discounted EV charge, network balancing and efficient integration of renewable energy into the grid.
Learn more about the energy marketplace in part 2/2 of this post.