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Report RSE 15000248

Testing the redox battery electrolyte circulation installed in the test of GD facility. standardization of batteries circulating electrolyte



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M. Scagliotti (RSE SpA), E. Micolano (RSE SpA) , L. Pellegrino (RSE SpA)

ACCUMULO 2014 - Energy Storage


The increase in installations of intermittent renewable energy plants requires a constant effort for the development of efficient energy storage systems, with reduced costs per unit power and/or energy and a long lifetime. The flow batteries (Redox) are one of the most promising technologies for installations with high power rating, more than tens of kW, and more than two hours of autonomy. For this reason, many stakeholders have shown interest in this technology. The activity described in this report has two main purposes: to model the battery Vanadium Redox (90 kWh) installed in the RSE GD Test Facility from 2001 and to analyze actions in the standardization field.

The modeling of the battery was performed on the basis of a series of tests with the aim to determine its behavior and characteristics. To describe the behavior of the battery, a first order electrical model was chosen, with parameters dependent on the state of charge and including self-discharge resistance. The circuital parameters of the model have been derived from test results, through best-fitting methods. The self-discharge test also allowed to obtain a simplified expression of battery equivalent self-discharge resistance.

The results obtained were used to implement the battery model in Simulink®. In this way it was possible to validate the chosen model, verifying that the error between the simulated and measured voltage during the tests was less than 2%. Simulations have also revealed the dependence of the self-discharge resistance from the battery current; in particular, it was observed that at high discharge rates, lower selfdischarge resistances have been obtained, therefore higher losses.

In the standardization field, RSE has gone on providing its contribution through the participation to the Joint Working Group JWG7 Flow Battery Systems for Stationary applications of the Technical Committees TC21 Secondary cells and batteries and TC 105 Fuel cell technologies of IEC. Two International standards dealing with safety and installation requirements and test methods for the performance evaluation of systems are currently under preparation.

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