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This review study focuses on the application of Computational Fluid Dynamics (CFD) in the investigation of gas-solids multiphase flow systems. The applicability and limitations of conventional models and recent developments of existing multiphase models for the prediction of gas-solids flows are thoroughly overviewed. Use of conventional Eulerian-Eulerian model for granular flows and Lagrangian approach incorporated with Discrete Element Method (CFD-DEM) are quite well proven, however some limitations restrict the use of these models in wide range of applications. Therefore, some new models have been introduced to model gas-solids flows, as example Dense Discrete Phase Model incorporated with Kinetic Theory of Granular Flow (DDPM-KTGF), Dense Discrete Phase Model incorporated with Discrete Element Method (DDPM-DEM) and Computational Particle Fluid Dynamics (CPFD) numerical scheme incorporated with the MultiPhase-Particle-In-Cell (MP-PIC) method. These models have been validated for certain applications under certain conditions, however, further validation of these models is still a necessity.

This paper describes the Fault Ride Through (FRT) capability of generators of a part of the 132 kV high voltage power network in Telemark region, Norway using a simplified power system simulator model. The organization, "European network of transmission system operators for electricity" (ENTSO-e) is introducing a network code for the Transmission System Operators (TSO) in Europe where the upper limit of the FRT requirement for 132 kV system is 0.25 s. However, according to the Norwegian network code, this limit is 0.40 s. The generators in the Norwegian power system are located in a distributed network and most of these are hydropower generators. The simulation results show that the structure of the Nordic power system enhances the system stability. The dynamic model of the power network is developed by using DIgSILENT PowerFactory simulation tool.