Haizea Gaztañaga

Energy management in hybrid and electric vehicles is a key factor to improve the operational performance and meet the efficiency objectives defined in the transport sector. Thus, optimized energy management strategies (EMS), before being integrated in a real system, need to be experimentally validated in test-bench platforms in order to identify the possible deviations from the expected simulation-based performance. This way, minimizing the time needed for implementation and field-test on the real application. An economical and flexible mean of validating these strategies is the Hardware-in-the-loop (HIL) simulation. Therefore, this work aims to present the design approach and comparison, by means of experimental tests, of two optimized (simulation-based) EMSs proposed for a hybrid electric bus (HEB) focusing on the real-time operational performance. Both EMSs handle the proper power split behaviour of the vehicle demand among a genset (internal combustion engine + electric generator) and a hybrid energy storage system (combining Li-ion batteries with super-capacitors). The experimental platform consists in a scaled test-bench emulating the electrical DC grid of a HEB. This test-bench, combined with software models to control the power electronic devices, allows to emulate the real behaviour of the genset, battery, super-capacitor, traction and auxiliary loads.

This paper presents an advanced market bidding and operation strategy for the joint participation of a solar plant with storage in Energy and Secondary Reserve Markets (SRM). A linear optimization is applied in order to calculate the optimal day-ahead and intraday market bids through a Model Predictive Control (MPC) approach, considering solar generation forecast, hourly market prices as well as battery acquisition, operating and degradation costs. Moreover, several rule-based strategies are selected to participate in secondary reserve markets, focused on more profitable and reliable hours through the estimation of market prices and the expected operation of the battery. Finally, the real-time operation tackles all the uncertain parameters, such as the reserve requirements and solar forecast errors, with the objective of achieving an optimal trade-off between market profits, battery costs and market technical fulfillments. Several market strategies have been compared in techno-economic terms with annual real market data. Regarding the most advanced strategy, market benefits are improved 6.42% from base case and non-fulfillment level of SRM is reduced up to 1.49%.

The present paper is focused on the evaluation of the economic influence of a battery lifetime model upon the optimal sizing and energy management strategy of a dual energy storage system (ESS) composed of Lithium-ion batteries and supercapacitors. The operation of a Hybrid Bus is taken as a case study in order to evaluate the effects of battery lifetime models’ accuracy on ESS sizing and operation in a heavy-duty application. For this purpose, two different lifetime models (a Wöhler-curve-based model and a semi-empirical model) were applied in the multi-objective optimisation of a hybrid electric urban bus. Differences up to ca. 8% on the daily operation costs and ca. 25% on the dual ESS costs were estimated depending on the lifetime model considered for the optimisation.

As the total number of installed wind farms is far from being negligible, an upgrading of their technology is essential to fulfill new interconnection requirements. Power electronics are considered to be a key technology to accomplish this task. In this paper the use of a Dynamic Voltage Restorer (DVR) for the improvement of the ride-through capability of fixed-speed wind farms is analyzed. The contribution of the DVR is analyzed by means of Hybrid real-time tests (with a reduced- scale physical prototype) and offline (full scale) simulations in PSCAD/EMTDC. The study highlights the great contribution of DVRs to the transient behavior of fixed-speed wind farms. However, it is shown their need of an active power handling capacity in order to deal with the active power generated by the wind farm that can not be exported to the grid during the fault In addition to that the limited contribution of the device in normal operating conditions is highlighted due to the admissible voltage range at the wind farm.