NUMBER
Objectives
The main objective of the NUMBER Project is to develop technology and new knowledge focused on the effects of induced degradation in lithium-ion battery storage systems. This degradation is largely due to the different charging/discharging conditions and regimes (cycling) that the batteries undergo during their useful life.
The aim is to size the lithium-ion battery storage systems much more appropriately for their use in renewable generation plants. To do this, work is proposed at all stages of the storage system's life, from its design to its operation in the plant, considering degradation models that incorporate the effect of the power converter and that allow, beyond the often imprecise estimation provided by the manufacturer, determining the optimal operating point that maximizes the return on investment of the system.
The specific objectives would be:
- Develop technology and new knowledge focused on the effects of induced degradation in lithium-ion battery storage systems.
- Develop the experimental models at the laboratory scale that allow investigating the applications of this technology.
- Establish an equivalent and high-precision electrical model, implementing it in a software tool that is fed with real operation data.
- Development and implementation of algorithms for online determination of the battery system's state of health (SoH), through signals injected by the power converter connected to it.
- Transfer the developments pointed out at the laboratory level to the field with respect to the technologies linked to the estimation of SoH.
- Explore the possibility of generally extending the proposed system and the various possible uses and functionalities to future projects.
Tasks performed
- Data analysis and environment: its objective is to determine the input variables to the dimensioning software.
- Definition of metrics for dimensioning: it aims to determine the KPIs (Key Performance Indicators) used to quantify the investment, based on technical-economic criteria.
- Implementation of the dimensioning tool: it focuses on the development of an optimal design and dimensioning software tool. The optimization algorithm for the dimensioning of the hybrid system (renewable generation combined with battery system) will be developed.
- Analysis of previous data (Li-Ion battery system): it focuses on the detailed analysis of the available data in the battery storage system installed in the plant.
- Development of a Measurement Acquisition System: the measurement acquisition system will be developed, which will allow capturing and recording variables with a sampling period at least 10 times smaller than the switching period of the power converter (kHz range) for long periods of time.
- Development of MATLAB/Simulink simulations (accelerated degradation models): Characterization of aging processes in storage systems is a task that requires a long time (years) for its development because it is necessary to find indicators that vary with aging since it is a slow process.
- Modification of the Control System of the converter for signal injection: The objective is to add a high-frequency excitation signal (at a frequency higher than the current regulator bandwidth and less than half the switching frequency of the power converter) that allows extracting the SoH, state of health, of the equipment with a high degree of accuracy.
- Global System Integration: integration of the techniques developed in all the previous tasks (converter data analysis, SCADA and plant data analysis, storage system model, and converter signal injection) into a unified tool for diagnosing the equipment's state of health.
Project stages
- Planning and design: The implementation of a software tool is proposed to achieve optimal design and sizing based on the mission profile of the storage system, the type of power converter, the price of energy, and various metrics and indicators (known in English as KPI, Key Performance Indicators) such as the LCoE (Levelized Cost of Energy) and the LCoS (Levelized Cost of Storage). In other words, the aim is to reduce the levelized cost of the system, both in terms of energy and storage.
- Operation in the plant: The aim is to determine the state of health of the equipment (SoH) through additional measurements or using data analysis already collected by the current control system.
Results Obtained
The EDPR result exploitation strategy involves the extension to other future renewable plant projects with storage systems based on lithium batteries, representing an improvement in the company's competitiveness both at the activity level and at the process level (maintenance of these systems), as a techno-economic optimization has been carried out that covers both the design phase of the project and the activity exploitation phase.
