**2. Materials and Methods**

The power system and market conceptual design methodology is described in this section. This method is framed under the framework of the NIST roadmap for smart grids [8]. The methodology proposed by the NIST was considered as a base to develop smart grid conceptual architectures by several authors and other standards [9,42]. In this regard, this methodology was selected as a meta architecture to develop the proposed upgrade of the existing architecture.

According to Reference [7], the first action is the specification of the roles/services that should be expected from the general implementation of smart grids. In addition to the traditional roles/services that are inherent in an electricity distribution system (i.e., generators and retailers), some additional agents should be expected from the combination of the new environmental requirements and advanced technology.

In this regard, the smart grid agents need to be designed to enable the system to successfully respond to the following needs:


It is important to highlight that the implementation of these agents can require the participation of new entities or the redesign of functions that will have to be performed by existing organizations.

A conceptual architecture is necessary to design a system capable of carrying out the roles/services that smart grids must perform according to the abovementioned needs. At this point, it is necessary to define a set of concepts that can be widely used along the description of the architecture:


In order to align the architecture with the required services of the system, an ontological definition is required according to Reference [7]. For doing so, the methodology proposed in NIST, shown in Figure 2, was used.

**Figure 2.** National Institute of Standards and Technology (NIST) conceptual architecture mapped onto the architecture matrix service orientation and ontology. Own elaboration based on Reference [8].

According to this procedure, four architectural levels must be considered to design the agents: business, information, automation, and technology. All these levels must be described to answer the four required layers: conceptual, logical, physical, and its implementation.

After this first context analysis, the interactions among the di fferent agents were carefully studied to satisfy the required relationship needs among them. The entities required to implement a smart grid are, in general, quite standard; however, some agents' activities assigned to these entities may not be so established and, in some cases, can be a bit confusing in the literature, where di fferent approaches to the same agents can be found.

The next section is devoted to presenting the novel conceptual architecture. Firstly, each agen<sup>t</sup> is defined based on the existing knowledge and literature, and the activities expected for the agen<sup>t</sup> are identified. According to these activities, the necessary physical components that each agen<sup>t</sup> owns are described. This includes assets like physical generators, transmission lines, etc. Finally, the power flows, operating service, or economic transactions of each agen<sup>t</sup> with the rest of them are described to fulfil the expected new requirements and functionalities of smart grids.

#### **3. Discussion of Agent Conceptual Architecture for Market Implementation**

The agents and nomenclature required for the upgraded conceptual architecture proposed in this paper are depicted in Table 1. The integration of di fferent types of distributed generation, storage, and demand response resources to provide firm power production, as well as the active participation of the customers, were considered in detail.


**Table 1.** Summary of agents and elements considered in the future electricity market framework.


**Table 1.** *Cont.*

The conceptual architecture was completed with the transactions allowed between agents, as summarized in Table 2, where economic, energy, and operation service transactions between the di fferent agents are proposed. A matrix representation of the allowed transactions among agents is shown in di fferent colors in this table. The possible transactions from the agen<sup>t</sup> in a row to the agen<sup>t</sup> in the column are represented by triangles. For instance, position T12 shows the transactions from consumers to generators, which are only economic, as consumers just pay generators for consuming electricity. On the other hand, T21 shows how generators provide energy to consumers. Another example could be position T43, where aggregators provide power flows and operating services to VPPs. In exchange for this, T34, VPPs make economic payments to aggregators.

**Table 2.** Summary of the transactions among agents on the proposed smart grid framework (-**:** economic transaction; -: energy transaction; -: operation service transaction).


The di fferent agents must accomplish these transactions (economic, energy, or service) in a coordinated way, based on what is required to interchange information with the rest of the participants in the power system. Traditional and new entities coexist in the proposed model. Agents whose activities change from traditional models are described in more detail in this chapter, while traditional ones are described when some of their original characteristics change.
