**2. Background**

## *2.1. Smart Grids*

Smart grids are physical networks that use cutting-edge technologies and equipment, enabling the interconnection of di fferent components through two-way networks that could achieve real-time optimizations to deliver electricity more reliably and e fficiently. Smart grids contain not only electricity interfaces, but also communication interfaces. With these, other stakeholders (utility companies) or domains (electricity markets) can be included for analysis and management. Future smart grids

can enable better operation and control, better network planning and maintenance, advanced smart metering infrastructure (AMI), and overall energy e fficiency for countries [14].

#### *2.2. Advanced Smart (Metering) Infrastructures*

Within smart grids, AMI systems are integrations of smart meters, communication networks, and data managemen<sup>t</sup> systems [14,15]. With the adaptation of narrowband(NB) powerline communication (PLC) technologies (e.g., Powerline Intelligent Metering Evolution (PRIME) and G3-PLC standards adopted in Europe), AMI enable real-time bidirectional communication between the TP (suppliers) and electricity consumers [16–18]. Smart meters are the most vital components within AMI. As smart energy sensors are installed in consumers' residences (households), smart meters can gather and transmit data including power consumption and electricity/gas bills on a real-time basis.

As illustrated in Figure 1, stakeholders of the smart metering system can include the consumers, energy suppliers, network operators, and data and communications companies (DCC) and TP. With smart meters, consumers can obtain near real-time and more accurate power usage data and bills, which helps them manage their energy usage. Energy suppliers (ES) are the utility companies that buy electricity from the wholesale market, then sell it to consumers. For instance, large British ES include British Gas, E-On, and SSE. Network operators (NO) (i.e., transmission system operators or TSOs, distribution system operators, etc.) construct, maintain, and operate the energy network, ensuring normal operation. These latter stakeholders can also benefit from smart meters: firstly, with the near real-time communication networks, utility companies can save money initially used for manual billing; secondly, network operators can implement demand-based managemen<sup>t</sup> responses, in particular under peak load times; and finally, operators and companies can detect fraud or electricity theft and thus improve their e fficiencies.

**Figure 1.** The structure of the current smart metering system.

The DCC collect energy consumers' data through the wide area network (WAN). Processed data are then sent to energy suppliers and network operators. DCC are responsible for ensuring compliance with the GDPR directive [19]. However, there is a lack of clarity about other stakeholders' responsibilities, making smart meters potentially fragile to a few privacy risks and concerns. These need to be identified and further explored if improvements in smart metering systems are to be made by or a ffecting several or all the stakeholders presented in the above figure. Before doing so, basic functions of smart meters are presented as following subsections.

#### *2.3. Functions of the Smart Metering System*

The European Commission identifies the 13 main functions of a smart meter and classifies them into five categories [20]. The most significant functions are listed in [21], which are billing correctness, grid operation and management, and additional consumer services. In addition, an emerging function is that of time-of-use (TOU) tariff.
