Maximising the potential of lithium-ion batteries for power grid applications

Modern power systems are adapting to reduce greenhouse gas emissions by incorporating renewable energy sources (RES), such as solar and wind power technologies. The issue lies in the intermittent nature of these sources, which poses serious challenges to grid stability. To overcome this, battery energy storage systems emerge as the key solution. In particular, the adoption of lithium-ion battery energy storage systems (Li-ion BESSs) as a flexible energy source has been rapid.

– Li-ion BESSs are widely used today mainly because of their superior technical characteristics and falling costs. However, their performances are non-linear, which makes determining their operational window in the field challenging. In addition, ambient operating conditions also impact their performances, adding to the complexity, explains Chethan Parthasarathy.

The non-linear characteristics of Li-ion BESSs, which are further influenced by parameters such as state of charge, temperature, depth of discharge, charge/discharge rate, and battery-ageing conditions, have traditionally hindered efficient and economical utilisation of these batteries, often leading to their underutilisation and over-sizing. Chethan Parthasarathy's doctoral research addresses these issues by developing accurate battery performance and ageing models and integrating them into their control structure.

One of the main contributions of his dissertation is the development of new adaptive control methods for grid applications. They allow optimal use of Lithium-ion BESSs by ensuring their performance thresholds are always upheld, thereby preventing both under-usage and over-usage of the battery systems. They also support higher penetration of RESs and help to keep the power grid stable.

– My main accomplishment has been embedding accurate battery models for battery integration in power system simulation environments. The development of such battery models is a complex process that involves extensive experimental testing and characterisation in a controlled laboratory environment. Eventually, this led to the setting up of a new battery cell testing laboratory at the University of Vaasa, reveals Parthasarathy.

Streamlining Li-ion BESS control and techno-economic study methods

Parthasarathy's dissertation also emphasises the inclusion of Li-ion BESS ageing degradation dynamics in their control topology. This approach allows real-time adaptation of energy and power outputs to minimise degradation, thereby extending the lifespan of Li-ion BESSs.

– This not only improves the longevity of batteries but also enhances understanding of their economic viability in power grid applications, explains Parthasarathy.

The technical contributions of the dissertation include the design of a grid-specific control architecture for active network management (ANM) schemes, the development of accurate battery models for Li-ion BESS grid integration studies, improved power system simulation modelling methods, and mapping of the required battery parameters for advanced control design. The dissertation also presents an ageing-aware adaptive control for Li-ion BESSs, enabling ANM simulations and techno-economic studies.

Doctoral dissertation

Parthasarathy, Chethan (2023) Accurate Battery Modelling for Control Design and Economic Analysis of Lithium-ion Battery Energy Storage Systems in Smart Grid. Acta Wasaensia 510. Doctoral dissertation. Vaasan yliopisto / University of Vaasa.

Publication pdf

Public defence

The public examination of M.Sc. Chethan Parthasarathy’s doctoral dissertation “Accurate Battery Modelling for Control Design and Economic Analysis of Lithium-ion Battery Energy Storage Systems in Smart Grid” will be held on Tuesday 20 June 2023 at noon at the University of Vaasa, auditorium Wolff.

It is possible to participate in the defence also online via Zoom, Password: 233106
Professor Pertti Kauranen (LUT University) will act as the opponent and Professor Hannu Laaksonen as the custos.