Energy Storage Technologies

Energy Storage Technologies within Use Cases

Aiming at developing viable business cases for the energy market, NETfficient has completed the design and definition of the five use cases: Peak Shaving and Ancillary Services in the Market, Homes, Buildings, Public Lighting and Aquarium Water Temperature Regulation. In detail, this includes the design of the single components, the requirements for storage technologies and ICT platforms.

Hybrid Energy Storage Solution – HESS design

Among the technological components NETfficient consortium has already completed the first part of Hybrid Energy Storage Solution – HESS design (components design, modelling and simulation of MV-HESS and LV-HESS completed) and is already in the middle of the assembling of the LV-HESS components and validation of prototypes.
MV HESS system (figure 14) is applied in all use cases. Its electrical parts consist of the three main elements: Inverter, Li-Ion System and Ultra-Capacitors System, linked together in the Connection Box. The Energy Management Platform (EMP) or the Distribution System Operator (DSO) communicates the HESS by means of the intelligent Node Management System (iNMS).
The Energy Management System (EMS) gathers all HESS information via the Intelligent Node Management System (iNMS) and is able to communicate with the three main elements of the HESS System. It will be connected to a supervisory control system, so that its power-flow can be controlled dynamically by the Energy Service COmpany (ESCO).
In general, the MV HESS system supports the services: Peak Shaving; Primary Reserve; Instantaneous Reserve; RES integration and Multiple services.

Figure 14: MV HESS- Communication and Control Structure
The HESS system essentially consists of a high energy battery storage as well as a high power Ultracapacitor storage. Both are connected to a high power grid tie inverter, which has a direct LV grid connection. Battery and inverter are connected directly to a common DC-Link, whereas the Ultracapacitor Bank is connected indirectly through a DC/DC-converter to maximize their energy utilization and narrow down the DC-link voltage range, respectively.

The system will be connected to a supervisory control system, so that its power-flow can be controlled dynamically by the ESCO (figure 15: Electrical Connection of MV HESS).

Considered that all the elements that compose the MV HESS system are switched on, the communications between elements are operative and the whole system is in standby mode state, the MV Hess system operates within the following steps:

There are several state machines working in parallel in different levels of management. These states machines are:
  • Connection/Disconnection state machine.Responsible of the step-by-step connection/disconnection of the elements of the MV HESS to the grid.
  • Enabling/Disabling state machine. Responsible of the enabling or disabling of the services provided in the different use cases depending on the state of the MV HESS.
  • Troubleshooting and resetting state machine. Responsible of the management of alerts and errors occurred in the MV HESS.
  • Monitoring of communications state machine.Responsible of the detection of the loss of communication between the iNMS and the element of the MV HESS.
The elements of MV HESS Solution
  • Battery Energy Storage System (BESS)
    • Li-Battery Management System (LiBMS)

    • Li-Ion Battery Storage
  • Grid Tie Inverter
    • Inverter Management System (IMS)
    • Inverter
  • Ultra-Capacitors
    • Ultracap DC/DC-Converter (UCC)
    • Ultracap Storage
    • Ultracap Management System (UCMS)
  • Energy Management System (EMS)
  • Intelligent Node Management System (iNMS)
  • LV to MV power transformer

Figure 15: Electrical connection of the MV HESS
The NETfficient MV and LV HESS and Battery Energy Storage Systems are designed to be used for different use case scenarios. To give a first insight one some of these state-of-the-art storage solution technologies in practice, some use case scenarios will be described within the following sections.

  • in Use Case - Peak Shaving and Ancillary Services in the Market the MV HESS supports an ESCO to deliver the agreed energy in case of a deviation of the wind / irradiation forecast for PV and wind generators. As the PV production data is not directly available for the HESS system it will be technically realized with charge and discharge commands by the ESCO.
    For this challenge, it contains background information for system exploitation which generates KPIs, Billing, Business reporting (logical view), background information for tactical decision for the supplying and power generation dynamically considering grid behaviour and him possibilities (operational view) and background information necessary for maintenance task orders (maintenance view) [ figure 7].

  • In Use Cases - Homes, - Buildings and - Public Lighting the LV HESS systems that will be installed, have a very similar scheme, but many different use case scenarios will be implemented. The differences between storage technologies and system configuration allow the study of the performance of each system under different conditions.

  • The demonstration buildings (Use Case - Buildings) i.e. are equipped with either Battery Energy Storage System (BESS) or BESS and Ultracapacitor storage systems.

  • Within Use Case - Public Lighting also a Battery Energy Storage System will be used.

  • In Use Case - Homes most homes (aggregated or standalone) will be equipped with a Battery Energy Storage System (one of the LV HESS solutions), but there are also homes that will be equipped with Li-ion Battery Storage (Power Rack) and Ultracapacitor Storage Systems, just 2nd-Life Electric Vehicle Batteries Storage or Hydrogen Storage System (for more information on NETfficient Technologies also see sections Demonstration, Partners and Project Events).

Hydrogen System (Hydrogen Power Box)

The Hydrogen Power Box™ (HPB) [figure 16] (used in Use Cases- Homes and Buildings) is an energy storage system based on hydrogen technology.
It is charged by electrical power from a renewable source (solar PV) and returns both heat and electrical power. It is the missing link between residential needs and the given solar system. It allows storing energy when available, and using it when needed. It provides a one-stop solution for both heat and power needs and it eliminates the need for a grid connection.

Unlike battery systems it can store for hours to months without degeneration/degradation as it uses compressed hydrogen gas as energy storage. This allows energy transfer even from one season to another. The basic form of storage, hydrogen, can be shared between houses as well or be used as zero emission fuel in hydrogen powered cars. The system is designed to be intelligent. It will monitor all energy flows in the house.

Figure 16: Hydrogen Power Box™