The recent deployment of distributed battery units in prosumer premises offer new opportunities for providing aggregated flexibility services to both distribution system operators and balance responsible parties. The optimization problem presented in this paper is formulated with an objective of cost minimization which includes energy and battery degradation cost to provide flexibility services. A decomposed solution approach with the alternating direction method of multipliers (ADMM) is used instead of commonly adopted centralised optimization to reduce the computational burden and time, and then reduce scalability limitations. In this work we apply a modified version of ADMM that includes two new features with respect to the original algorithm: first, the primal variables are updated concurrently, which reduces significantly the computational cost when we have a large number of involved prosumers; second, it includes a regularization term named Proximal Jacobian (PJ) that ensures the stability of the solution. A case study is presented for optimal battery operation of 100 prosumer sites with real-life data. The proposed method finds a solution which is equivalent to the centralised optimization problem and is computed between 5 and 12 times faster. Thus, aggregators or large-scale energy communities can use this scalable algorithm to provide flexibility services.
This paper presents an electrical battery model for lithium-ion (Li-ion) batteries that can be used for dynamic simulations of hybrid electric non-road mobile machinery (NRMM) and other vehicles. Although the model has been developed mainly for large vehicle batteries with Li-ion based chemistries, it can be used for other battery chemistries as well. The parameters can be extracted from simple measurement sets. The model calculates e.g. state-of-charge, terminal voltage, and open-circuit voltage. In this paper, the model structure and parameter extraction are explained in detail, and a model for a 25.9 V lithium-ion polymer battery module with 40 Ah cells is presented. Parameters are extracted from experimental measurements and the model is validated by making another experiment with more realistic hybrid electric NRMM current profile.
Interest to hybridize mobile work machines has increased substantially during ongoing decade. Reasons for increasing interest are mainly tightening emission regulations and trend of rising fuel prices. To get better understanding for the benefits of hybridization, Helsinki University of Technology (TKK) has started 5 years project to research different aspects, how to improve fuel economy in mobile work machines. For case work machine is chosen an underground mining loader which will be first researched as conventional version and then it will be converted to a hybrid version. The tests for conventional version were done in the early 2009 and for hybridized version till the end of 2010. The results will be then compared to each other.
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