Upper layer: central management and the role of the SCADA

According to the laboratory roadmaps, there are three main data managers and control devices planned in the laboratory: the aggregator, the EMS, and the SCADA. The initial development of this SCADA is the core of the project.

The orders to the LCs are given from the SCADA, as well as it monitors and gathers all the necessary information from the local elements. It may also act as a communication gateway between the EMS and the LCs. The EMS provides smart energy management based on real-time optimization of numerous data, i.e. history, prices, forecasts. The aggregator, as the hierarchically top manager may give restrictions, and define the flexibility which influence the behaviour of the network.

The microgrid is prepared to run several types of projects and scenarios. The different projects might need completely different setups, which in general are called demos. These demos are usually defined and parametrized from the SCADA. As it has already been mentioned before, and can be seen on Figure 10, there are two modules of the microgrid elements which need distinction: the configuration and the monitoring module. In configuration module all the important planning and arrangement of each element shall happen. In the monitoring module the LCs control the cabinets on power, and the LCs are supervised by the SCADA, which then communicates with other agents and may act as a manager. The following Chapters introduce what exactly configuration and monitoring means from each participant’s point of view, when running an emulation.

2.3.3.1. Configuration module

The configuration module is mainly used during the establishment and arrangement of a scenario. Figure 13 shows the communication exchanges between the main central bodies under this module. In the configuration module the SCADA would define the mode of the emulation: manual or auto. This distinction gives different roles to the different elements of the network.

- Manual mode means that the SCADA and the whole microgrid work more independently from the EMS. The SCADA controls and monitors the microgrid, and it ignores any messages coming from the EMS. This mode gives higher flexibility for the operation; however, it is less suitable for automatic control algorithm based on energy price and forecast.

- Auto mode of the network changes the roles, and most of the control information derives from the EMS. It optimises and give commands to the controllable elements of

the system depending on the forecasts of price, demand and generation. In automatic mode the SCADA system would only behave as a gateway, communicating the EMS orders towards the LCs.

Apart from setting the mode of a scenario, the SCADA is responsible for the following fields:

- Forecast: the SCADA should store information in its database regarding energy price, demand forecast and meteorological conditions and forecast;

- Profiles: profile generation and definition, their communication towards each LC;

- Scenario: The SCADA gives all the preparation and parameters to the LCs to start a scenario emulation:

o Minimum and maximum active power in W,

Figure 13: Information exchange between the participants in the configuration module

o Minimum and maximum reactive power in var, o The type and profile of the emulation,

o The mode of each LC,

o The initial minute of the profile when the demo starts,

- Control: the SCADA should be connected to all elements of the network and be able to start, stop, enable or disable any of them. Moreover, as mentioned before, the SCADA shall be responsible for the demo configuration.

The principal role of the other main body, the EMS would be to collect and transmit information from external databases (Influx Database), and to create long-term strategies for control mechanisms. These information packages include historical data of demand, prices, forecasts, and any other types of necessary, previously configured information. These packages are then sent to the SCADA, which stores them in its MySQL database.

2.3.3.2. Monitoring module

The monitoring and supervising module is responsible for the data acquisition, transmission and storage, as well as the real-time control of the microgrid network. Figure 14. shows the communication exchanges between the central bodies.

Under the monitoring module the SCADA is responsible for the following fields:

- Historical Data Treatment: data storage in MySQL Database, presentation of results, historical data, and reports,

- Acquisition of Data: individualized information shall be collected and concentrated from all devices, in real time. For such purpose, the SCADA would be equipped with communication drivers, TCP/IP server, Modbus TCP/IP client, and an MQTT Client Driver.

- Alarms: generation of alarms based on pre-defined normal and not normal conditions of the LCs,

- Real-time data visualization: graphical presentation of the pre-configured parameters, as a function of time,

The EMS would be provided information by the aggregator, as well as by external databases (Influx DB). The EMS sends these information packages to the SCADA via Modbus TCP/IP to be used for control.

The SCADA is connected to the LCs via Modbus TCP/IP and supervises as well as controls each of them. It receives and transmits data of each of their states, and sends them active and

reactive power setpoints, which then the LCs apply in their sequence. These setpoints may be calculated by the EMS in case of auto mode, and by the SCADA in case of manual mode.

Figure 14: Information exchange between the participants in the monitoring module