» Architecture

Overall DEMOCRAT Project Architecture

The overall DEMOCRAT project architecture is made of several macro components, representing the micro grid. The image below depicts the overall architecture, in line with the SGAM model.

The Energy Services Simulator Platform provides the following features:
  • Emulate market context;
  • Simulation of Energy Markets (e.g. introduce different energy rates);
  • Simulation of Demand Response;
  • Technical Simulation: enabling to trigger the micro grid operation in off-grid mode (e.g. service interruption).

The Private Micro-grid management System provides the following features:
  • Monitoring of the micro grid
  • Interaction with corporate system such as SCADA systems;
  • Compute real-time operation and plan future operation of the micro grid
  • Interface with end-users and/or network operators

The Storage Controller provides the following features:
  • Key enabler of micro grid operation;
  • Peak-shaving;
  • Buffer for EV charging - reduce adverse influence on the grid during the fast charging process,
  • Reduction of demand variability
 

The Battery Energy Storage System Architecture

The architecture of the Battery Energy Storage System (BESS) is described as follows, comprising also the physical components of the microgrid:

  • The Power Conversion System – commercially designated by Efacec as the “PCS Block”
  • The Battery System – commercially designated by Efacec as the “Battery Block”
  • The micro grid testbed, which is composed by the following circuits:
    • Low Voltage (400 V)
      • Connection to the industrial LV grid of Efacec
      • Connection to the electrical circuit of one building, which can be fed separately by this micro grid
      • An external connection to a load bank
      • An external connection to an optional diesel generator
      • An external connection to a LED street lighting circuit
      • An external connection to an EV charging station
    • Medium Voltage (15 kV)
      • Connection to the industrial MV grid of Efacec
The DEMOCRAT project’s BESS architecture is depicted below. It comprises the main components, the MV and LV circuit, the DC circuit, the ancillary services circuit, the main communication components and the main analogue sensors and inputs. Moreover, it comprises the infrastructure grid and the main circuits of the microgrid.
 

More details about the architecture can be found in this link. The details shown also comprise analogue and digital inputs, as well as control outputs.

The main components of the BESS architecture are described in the following pictures, each providing some details about each main component.
Battery Block

The Battery Block holds the battery system. It was designed to be equipped with up to 1 MWh capacity of Lithium-ion batteries.

The initial sizing of the DEMOCRAT project is 209 kW / 209 kWh, corresponding to two racks of batteries, comprising their BMS and the Master BMS.

The selected battery manufacturer was Pylontech.

The system was designed to hold different kinds of batteries, actually being agnostic regarding the technology or the manufacturer. Moreover, the system can also hold ultracapacitors technology.

The system holds a DC bay providing switching and protection for each DC circuit coming from each battery rack.

The battery system comprises several communication interfaces, as follows:

  • Between each BMS and the Master BMS: CAN over a serial port
  • Between the Master BMS and the Energy Storage Controller: either MODBUS RTU over RS485 serial port or MODBUS TCP over an Ethernet LAN Switch
  • Fire intrusion/detection system and the Energy Storage Controller: either MODBUS RTU over RS 485 port or digital inputs
  • HVAC system and the Energy Storage Controller: either MODBUS RTU over RS485 serial port or MODBUS TCP over an Ethernet LAN Switch
PCS Block

The PCS Block holds the Power Conversion System. Basically, it provides the electrical interface between the battery system (Battery Block) and the electric grid infrastructure.

The PCS Block of the DEMOCRAT project was designed in order to interface both the LV and the MV grid, exclusively. Moreover, the PCS Block can also accommodate a circuit to feed a microgrid adjacent to the PCS Block, comprising a load bank, a public lighting circuit, an EV charging station and a diesel genset. The PCS Block can also serve a building segment within the Efacec facilities, corresponding to a 250 kVA load connected to the Efacec facilities’ LV grid.

For more details concerning the main PCS Block components, please press here.
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