OPTIMIZED BOGIE SYSTEM DAMPING WITH RESPECT TO SAFETY AND COMFORT

Here the lateral damping (two dampers) is optimized and investigated with respect to safety and comfort for an eight degree of freedom model of a train bogie. The train bogie model is nonlinear due to the excitations caused by the irregularities and the wheel–track interface forces. Train running at different speeds will have different optima and optimal damping parameters with respect toboth comfort and safety. The aim is to optimize the dynamic behavior for a wide range of forward service speeds up to 300 km/h. A multiobjective optimization routine is used and the results are presented in terms of Pareto fronts. To optimize the behavior semi–active functional componentsare required. A scheme to control semi–active lateral damping components with respect to forward speed is suggested. This can significantly improve the dynamic behavior with simultaneously respect to safety and comfort. Finally, we investigate the use of two lateral damping components with the possibility to change behavior at a certain switch time. At least for some service speedsthese semi-active damping components are find to be able to improve the dynamic behavior. The understanding of the influence of the design parameters is valuable in further improving the general performance of a high speed train with respect to safety and comfort

Vibration dynamics of high speed train with Pareto optimized damping of bogie suspension to enhance safety and comfort

A methodology to find the optimized, with respect to safety and comfort, lateral damping of both the primary and secondary suspensions of a bogie system for a high speed train (HST) has been developed, implemented and evaluated. The vibration dynamics of three-car HST with safety-comfort Pareto optimized lateral damping of bogie system is analyzed. The sensitivity of vibration dynamics of the HST having Pareto optimized lateral damping and traveling with 250 km/h is studied for different vehicle speeds, wheels and rails wornness, train service loads and frictions between wheels and rails. Numerical results show that Pareto optimized lateral damping of bogie system can significantly improve passenger comfort while maintain safety and reliability of HST performance

Vibration dynamics of high speed train with Pareto optimized damping of bogie suspension to enhance safety and comfort

A methodology to find the optimized, with respect to safety and comfort, lateral damping of both the primary and secondary suspensions of a bogie system for a high speed train (HST) has been developed, implemented and evaluated. The vibration dynamics of three-car HST with safety-comfort Pareto optimized lateral damping of bogie system is analyzed. The sensitivity of vibration dynamics of the HST having Pareto optimized lateral damping and traveling with 250 km/h is studied for different vehicle speeds, wheels and rails wornness, train service loads and frictions between wheels and rails. Numerical results show that Pareto optimized lateral damping of bogie system can significantly improve passenger comfort while maintain safety and reliability of HST performance

OPTIMIZED BOGIE SYSTEM DAMPING WITH RESPECT TO SAFETY AND COMFORT

Here the lateral damping (two dampers) is optimized and investigated with respect to safety and comfort for an eight degree of freedom model of a train bogie. The train bogie model is nonlinear due to the excitations caused by the irregularities and the wheel–track interface forces. Train running at different speeds will have different optima and optimal damping parameters with respect toboth comfort and safety. The aim is to optimize the dynamic behavior for a wide range of forward service speeds up to 300 km/h. A multiobjective optimization routine is used and the results are presented in terms of Pareto fronts. To optimize the behavior semi–active functional componentsare required. A scheme to control semi–active lateral damping components with respect to forward speed is suggested. This can significantly improve the dynamic behavior with simultaneously respect to safety and comfort. Finally, we investigate the use of two lateral damping components with the possibility to change behavior at a certain switch time. At least for some service speedsthese semi-active damping components are find to be able to improve the dynamic behavior. The understanding of the influence of the design parameters is valuable in further improving the general performance of a high speed train with respect to safety and comfort

The cost dynamics of hydrogen supply in future energy systems – A techno-economic study

This work aims to investigate the time-resolved cost of electrolytic hydrogen in a future climate-neutral electricity system with high shares of variable renewable electricity generation in which hydrogen is used in the industry and transport sectors, as well as for time-shifting electricity generation. The work applies a techno-economic optimization model, which incorporates both exogenous (industry and transport) and endogenous (time-shifting of electricity generation) hydrogen demands, to elucidate the parameters that affect the cost of hydrogen. The results highlight that several parameters influence the cost of hydrogen. The strongest influential parameter is the cost of electricity. Also important are cost-optimal dimensioning of the electrolyzer and hydrogen storage capacities, as these capacities during certain periods limit hydrogen production, thereby setting the marginal cost of hydrogen. Another decisive factor is the nature of the hydrogen demand, whereby flexibility in the hydrogen demand can reduce the cost of supplying hydrogen, given that the demand can be shifted in time. In addition, the modeling shows that time-shifting electricity generation via hydrogen production, with subsequent reconversion back to electricity, plays an important in the climate-neutral electricity system investigated, decreasing the average electricity cost by 2%–16%. Furthermore, as expected, the results show that the cost of hydrogen from an off-grid, island-mode-operated industry is more expensive than the cost of hydrogen from all scenarios with a fully interconnected electricity system

The value of flexible fuel mixing in hydrogen-fueled gas turbines – A techno-economic study

In electricity systems mainly supplied with variable renewable electricity (VRE), the variable generation must be balanced. Hydrogen as an energy carrier, combined with storage, has the ability to shift electricity generation in time and thereby support the electricity system. The aim of this work is to analyze the competitiveness of hydrogen-fueled gas turbines, including both open and combined cycles, with flexible fuel mixing of hydrogen and biomethane in zero-carbon emissions electricity systems. The work applies a techno-economic optimization model to future European electricity systems with high shares of VRE. The results show that the most competitive gas turbine option is a combined cycle configuration that is capable of handling up to 100% hydrogen, fed with various mixtures of hydrogen and biomethane. The results also indicate that the endogenously calculated hydrogen cost rarely exceeds 5 €/kgH2 when used in gas turbines, and that a hydrogen cost of 3–4 €/kgH2 is, for most of the scenarios investigated, competitive. Furthermore, the results show that hydrogen gas turbines are more competitive in wind-based energy systems, as compared to solar-based systems, in that the fluctuations of the electricity generation in the former are fewer, more irregular and of longer duration. Thus, it is the characteristics of an energy system, and not necessarily the cost of hydrogen, that determine the competitiveness of hydrogen gas turbines

The chemical pulp mill as a flexible prosumer of electricity

Chemical pulp mills act as industrial-scale prosumers of energy, in that they demand heat and electricity for the production processes while supplying heat and electricity from the combustion of by-products. As such, they have potential relevance as providers of flexibility to the electricity system, supporting the integration of variable renewable electricity generation. In this study, a novel dispatch optimisation model is presented and applied to a generic mill, covering the production processes, boilers, and turbines, together with the associated storage of intermediate products. We analyse the trade in electricity between the mill and the central grid, the economic value of pulp mill flexibility, and the internal dynamics of the mill, when flexibility measures in different parts of the mill are combined. The results show that the suggested flexibility measures increase the amount of sold electricity during high-value hours and reduce the amount of sold electricity during low-value hours. In the present electricity market, the value of the electricity traded with the central grid is, thereby, increased by 1–8% compared to steady-state operation, without impacting the pulp production volume. The results reveal both synergies and conflicts between the different flexibility measures, underlining the importance of mill-wide optimisation

Exploring the competitiveness of hydrogen-fueled gas turbines in future energy systems

Hydrogen is currently receiving attention as a possible cross-sectoral energy carrier with the potential to enable emission reductions in several sectors, including hard-to-abate sectors. In this work, a techno-economic optimization model is used to evaluate the competitiveness of time-shifting of electricity generation using electrolyzers, hydrogen storage and gas turbines fueled with hydrogen as part of the transition from the current electricity system to future electricity systems in Years 2030, 2040 and 2050. The model incorporates an emissions cap to ensure a gradual decline in carbon dioxide (CO2) levels, targeting near-zero CO2 emissions by Year 2050, and this includes 15 European countries. The results show that hydrogen gas turbines have an important role to play in shifting electricity generation and providing capacity when carbon emissions are constrained to very low levels in Year 2050. The level of competitiveness is, however, considerably lower in energy systems that still allow significant levels of CO2 emissions, e.g., in Year 2030. For Years 2040 and 2050, the results indicate investments mainly in gas turbines that are partly fueled with hydrogen, with 30–77 vol.-% hydrogen in biogas, although some investments in exclusively hydrogen-fueled gas turbines are also envisioned. Both open cycle and combined cycle gas turbines (CCGT) receive investments, and the operational patterns show that also CCGTs have a frequent cyclical operation, whereby most of the start-stop cycles are less than 20 h in duration

Impact of electricity market feedback on investments in solar photovoltaic and battery systems in Swedish single-family dwellings

The profitability of investments in photovoltaics (PVs) and batteries in private households depends on the market price of electricity, which in turn is affected by the investments made in and the usage of PVs and batteries. This creates a feedback mechanism between the centralised electricity generation system, and household investments in PVs and batteries. To investigate this feedback effect, we connect a local optimisation model for household investments with a European power generation dispatch model. The local optimisation is based on the consumption profiles measured for 2104 Swedish households. The modelling compares three different scenarios for the centralised electricity supply system in Year 2032, as well as several sensitivity cases. Our results show total investment levels of 5–20 GWp of PV and 0.01–10 GWh of battery storage capacity in Swedish households in the investigated cases. These levels are up to 33% lower than before market feedback is taken into account. The profitability of PV investments is affected most by the price of electricity and the assumptions made regarding grid tariffs and taxes. The value of investments in batteries depends on both the benefits of increased self-consumption of PV electricity and market arbitrage

Impacts of demand response from buildings and centralized thermal energy storage on district heating systems

\ua9 2020 The Author(s) Energy use for space heating is a substantial part of total energy end use and heating systems can offer some flexibility in time of use, which should be important in future energy systems to maintain balance between supply and demand. This work applies a techno-economic, integrated, demand-supply optimization model to investigate the combined effect of using demand-side flexibility from buildings, by allowing for indoor temperature deviations (both up- and downward from the set-point), and supply-side flexibility, by applying thermal energy storage (TES), on the operation of district heating (DH) systems. The results indicate that the potential for increased indoor temperature, i.e., demand response (DR), is concentrated to multi-family and non-residential buildings (heavy buildings with high time-constants), while the potential for downregulation of the temperature, i.e., operational energy savings, is utilized to a greater extent by single-family buildings (light buildings). It is also evident that the value of DR diminishes in the presence of a supply-side TES. We show that applying both the demand-side flexibility and a centralized TES is complementary from the heating system perspective in that it results in the lowest total space heating load of the buildings and the lowest running cost for the DH system