Graybar

Currently, the deployment of renewable energy sources (RESs) is rapidly increasing in transactive energy markets (TEMs). The effects of RES uncertainties on transactions and power markets are increasing with the penetration of RESs into the system. The integration of RESs into TEMs brings new challenges to the security and economic operation of the power markets and also makes significant changes in the scheduled transactions and economic dispatch of power generation units in the power markets. Therefore, it is important to manage RES uncertainties and reduce their impacts on transactions as well as conventional generation units for the secure and economic operation of TEMs. This paper proposes a coordinated stochastic dispatch model for the optimal dispatch of transactions and conventional generation units without any security and economic issues in TEMs considering RES uncertainties. In this work, the penalty cost of transactions and the rescheduling cost of power generations are incorporated with the proposed dispatch model to reduce the variations in scheduled transactions and power outputs of generation units. For more effective analysis of the impacts of RES uncertainties on transactions in terms of their scheduled sizes, three new indices are introduced in this work. Based on the information provided by these indices, the system operators or power traders can take suitable/appropriate actions for the secure and economic operation of TEMs against RES uncertainties. In the proposed model, the stochastic nature of solar and wind units is modelled by using the Weibull distribution function. A modified IEEE 57-bus system has been adapted to illustrate the performance of the proposed dispatch model. The optimal solutions of the proposed dispatch model are determined using the Moth Flame optimization algorithm.

Advanced additive manufacturing opens ways to improve gas turbine fuel nozzles to enhance engine durability and performance while reducing gas emissions including NOx, CO, and soot. Additively building complex fuel passages enables engineers to better control the fuel-air mixing and its burning, not only in gas-only but also in dual fuel engine configurations. Dual fuel engines have additional requirements for proper liquid jet trajectory and spray quality and droplet evaporation that needs to be met through the careful injector configuration within the liquid fuel cartridges. Additionally, recent liquid fuel cartridges in the combustor inject a set of discrete liquid jets into a non-uniform cross flow, which can lead to complex interactions between liquid jets and incoming air during the jet breakup and evaporation phases. This can be an engineering challenge during engine development because the classical evaporation models need to be calibrated to get the accurate evaporation profile. This paper investigates the evaporation profile of liquid jets in non-uniform cross flow along the combustor axis numerically and experimentally. Three different crossflow temperatures are simulated and the effect of crossflow temperature on the spray evaporation and residual droplet characteristics is documented. Two different evaporation models, diffusion controlled, and convection/diffusion controlled based evaporation models have been utilized to predict the spray trajectory and spray density after the evaporation. Results were compared with experiments conducted at University of Cincinnati Research Institute (UCRI) with reasonable agreement. The fundamental physics and understanding of spray evaporation can help the combustor engineers to configure liquid fuel injectors that provide a suitable fuel/air mixture distribution for flame stabilization as well as complete combustion with minimal soot and CO emission in gas turbine engines.

The National Renewable Energy Laboratory and General Electric (GE) are partners within the Additive and Modular-Enabled Rotor Blades and Integrated Composites Assembly (AMERICA) project. AMERICA aims to develop advanced manufacturing solutions to reduce labor and cycle time while increasing recyclability of wind turbine blades. The project is funded by the U.S. Department of Energy's Advanced Manufacturing Office. This paper describes the techno-economic and life cycle analysis of the novel manufacturing process applied to the 15-meter long tip of the blade of a representative 3.4 MW land-based wind turbine. We establish a comparison to a standard manufacturing process, highlighting challenges and opportunities. Several uncertainties affect the analysis, but we highlight an opportunity space. With the current set of assumptions, the tip adopting advanced manufacturing is predicted to lower labor by 21%, cycle time by 39%, and total blade tip costs by 15% while simultaneously increasing production quality and adopting recyclable thermoplastic resin. A life cycle analysis returns comparable metrics for climate change impact and embodied energy between the two processes.

The development of regional power pools and the increased penetration of renewable energy in Africa are crucial goals that pose several challenges, including the need for accurate power system models to achieve grid stability. The paper emphasizes the significance of model verification in accurately representing generators and loads. It proposes a methodology that captures the behaviors of synchronous power plant generators, excitation systems, and turbine governor systems to determine model parameters suitable for operational and planning studies. The methodology has been implemented in the field and demonstrated through several practical case studies. To illustrate the effectiveness of the proposed methodology further, the paper conducts a simulation case study using the IEEE 9-bus system to compare the dynamic performance of a test network model with more accurate plant and load characteristics. The findings indicate that generator testing can significantly enhance the fidelity of the models of generator units in a network model with complex loads. This paper may be of interest to Transmission System Operators and Planners seeking to improve their long-term planning and operational studies, as well as those who need to synchronize multiple synchronous areas.

Advanced additive manufacturing opens new ways to improve gas turbine fuel nozzles to enhance engine durability and performance while reducing gas emissions including NOX, CO, and Soot. Additively building complex fuel passages enables engineers to better control the fuel-air mixing and its burning, not only in gas-only but also in dual fuel engine configurations. Dual fuel engines have additional requirements for proper liquid jet trajectory and spray quality that needs to be met through the careful injector configuration within the liquid fuel cartridges. Additionally, liquid fuel cartridges in the combustor are consolidated into one cartridge with a set of discrete injectors in near proximity for cost benefits, which leads to complex multi-fuel injector designs. This can be an engineering challenge during the engine development because the traditional specifications for spray characterization (that are based on classical correlations for single jet in crossflow) don't necessarily hold true for multiple discrete jets. In addition, the flow approaching the discrete jets is not uniform in recent combustor architectures. Spray characteristic of multiple liquid jets in crossflow is very different from a single jet's behavior, primarily due to axial shadowing effects and lateral jet-to-jet interactions. This paper highlights the main differences in droplet sizes and jet trajectories based on the experiments conducted at University of Cincinnati Research Institute (UCRI), as well as comparable CFD results performed at General Electric Combustion Engineering. The shadowing effect will result in larger droplet sizes that can significantly impact the combustion performance. The fundamental physics and understanding of these interactions can help the combustor engineers to specify liquid fuel injectors that provide a suitable spray quality for flame stabilization in gas turbine engines.