Use of EV battery storage for transmission grid application

Transcription

1 Use of EV battery storage for transmission grid application A PSERC Proposal for Accelerated Testing of Battery Technologies suggested by RTE-France Maryam Saeedifard, GT James McCalley, ISU Patrick Panciatici & Thibault Prevost (RTE)

2 Observations With rapidly evolving smart grids and Electric Vehicles (EVs), battery has emerged as the most prominent energy storage technology. Battery chemistry/technology also plays an important role in the amount and duration of energy availability.

3 Observations The specific characteristics and needs of the smart grid and EVs, such as deep charge/discharge protection, accurate State of Charge (SOC) monitoring, State of Health (SOH), and round trip efficiency estimation, necessitates the need for more accurate and efficient battery models and battery management system (BMS). The BMS not only controls the operational conditions of the battery to prolong its life and guarantee its safe operation, but also provides accurate SOC, SOH and round-trip efficiency.

4 Functionality of BMS smart grid and EVs: Minimize the cost involved in energy production, storage, distribution, and maintenance and operation while maximizing lifetime, safety and reliability. Observations

5 Observations Battery performance is dependent upon environmental conditions (extremely nonlinear behavior). Batteries may be exchangeable generating a market for charging stations. Charging stations may: (a) optimize charging cycles, and (b) provide ancillary services to the grid. Utility size charging stations? Optimization of the operational cycle requires a realistic battery model. Problem is challenging considering the various technologies. Models must be verified by experiments

6 Project Objectives Battery technologies: flow, sodium ion, sodium-sulfur, nickel-cadmium, lithium-ion, nickel-metal-hydride, lead-acid. Of these, lithium-ion, nickelmetal-hydride, lead-acid have been attractive in EV and PHEV vehicles. Focus on batteries used by EVs and PHEVs, and utility size batteries (flow batteries). Regarding EV & PHEV batteries, we will consider use of both new and second-hand battery technologies. The objective of this project will be to investigate: Considering battery performance indicators (e.g., efficiency, lifetime), what kind of grid services are EV/PHEV-battery technologies most suited to provide? Flow batteries? Energy arbitrage (load leveling); primary frequency response; regulation (variability); reserves (backup); peak capacity; congestion management, offsetting transmission needs; reducing thermal cycling; voltage support.

7 Present Approach / Challenges Popular electro-thermal models proposed for batteries. The number of RC branches is a tradeoff between accuracy and complexity. The equivalent circuit parameters are dynamically being changed and are nonlinear functions of SOC, temperature and C/D-rate.

8 Challenges Battery is an electro-chemical component and the dynamics need to be accurately modeled by using online parameter identification algorithms so that the model parameters can be updated as fast as they change. Accordingly, accurate algorithms are required to gauge the battery SOC and SOH so that the battery reliability, lifetime, and safety can be extended and its exploitation for various applications can be optimized. Models must be experimentally verified.

9 Approach 1. Review: The literature will be reviewed to identify the grid services that batteries can provide, characterizing each service in terms of the nature of stress it imposes on the battery, e.g., length of charge/discharge cycle ratio power/energy 2. Software modeling: Computer models for each battery technology will be identified or developed. Experimental verification of models. 3. Configurations: Computer models will be used to identify/develop appropriate configurations for each battery technology, in terms of: Cooling system Arrangement (parallel or series) Inverter type/topology This step is important given that battery technologies originate from EV/PHEV applications but will be used in a stationary application. 4. Software testing: The performance of each battery technology and configuration will be assessed via computer model for each grid service considered 5. Hardware Testing: The performance of each battery technology and configuration will be assessed via hardware in the lab.

10 Hardware Testing Hardware tests: impact of fast and deep cycling impact of fast and shallow cycling impact of non utilization at low levels of energy impact of non utilization at high levels of energy impact of temperature (cover the range of anticipated environmental conditions) impact of voltage charging

11 STRESS (temp) Accelerated Life Testing Accelerated life testing is testing that uses aggravated conditions to speed up normal deterioration processes. There are at least 2 deterioration mechanisms for batteries: Temperature-dependent: Surface film on electrodes grow, increasing the internal resistance of the battery. We can accelerate this deterioration mechanism by operating the battery at higher temperatures. Charge/discharge cycle: We will accelerate this deterioration mechanism by exposing batteries to rapid, but controlled charge/discharge cycles. Number of cycles International Energy Agency, Hybrid & Electric Vehicle Implementing Agreement, Task 21, Accelerated Aging Testing for Li-ion Batteries, available at Y. Aoki and A. Okuyama, Lithium-ion secondary battery accelerated testing, Technology Report 70, Technology Development Department, ESPEC Corp., available at IonSecondaryBatteryAcceleratedTesting.pdf. S. Fitzpatrick, S. Haggis, M. Murrary, C. Foshee, Lithium ion battery accelerated life testing report, November, 2011, available at

12 Obtaining batteries It will be necessary to obtain a number of different types of batteries and specialized equipment for this project. This may require additional funding beyond what is standard for a normal PSERC project. We may request targeted funds for this purpose.