The increasing integration of distributed electricity generation and storage (together referred to as distributed energy resources, DER), including electric vehicles and flexible demand, requires significant changes in how distribution systems are planned and operated. The only way to make this transformation feasible is through the introduction of digital monitoring and control capabilities, and by enabling distribution system operators (DSOs) to make use of these capabilities. This series of blog posts discusses the basic principles behind the smart electricity distribution system, provides an overview of resulting security challenges, and hints at the solutions offered in the SDN-microSENSE toolbox.
Smart Electricity Distribution
In a smart electricity distribution system, the system operator is able to monitor the state of their grid infrastructure in near real time. Based on a combination of measurement data collection and power flow simulations, they supervise the loading of lines, cables, and transformers, detect looming violations of voltage limits, and identify unintentional islands resulting from tripped protection relays. Further monitoring data can support system maintenance through an indication of asset health. Since existing distribution systems generally do not have the necessary monitoring facilities (measurement devices and communication infrastructure), a roll-out of Smart Meters and Smart Meter Gateways is required.
Besides monitoring and supervision, the other major new required capability is control access. Substations are increasingly equipped with automation functions that allow remote operation and grid reconfiguration. System operators also receive access to DER remote control interfaces, allowing them to set operating modes or enforce set-points or operating state. The system operator must be able to override user settings and commands when needed. These new capabilities give the system operators the means required to guarantee secure system operation in systems with high DER penetration. Remote control access relies on communication infrastructure, too. The corresponding remote terminal units (RTU) can be directly connection to communication networks, or can also be linked to the DER control communication endpoint built into Smart Meter Gateways in many countries.
As long as no limitation of operating mode and state is imposed by the distribution system operator, the user can either use their DER to optimize their own operation (e.g., optimizing towards maximum self-consumption of electricity), or to provide services to third parties, selling energy and/or flexibility. These optimisation and service provision opportunities provide the user with the economic incentives required to making the DER investment happen. Coordinated planning between system operator and DER user is required to ensure that restrictions and limitations in operation may only need to be imposed by the DSO temporarily and do not threaten any party’s business case.