To achieve both accumulator pressure regulation and generator power tracking for a Compressed Air Energy Storage (CAES) system, a nonlinear controller designed base on an energy based Lyapunov function. The control inputs for the storage system are the pump/motor displacements inside the hydraulic transformer and the liquid piston air compressor/expander. While the pump/motor inside the liquid ...

Hydraulic turbines are widely used to meet real-time electricity demands. Computational fluid dynamic (CFD) techniques have played an important role in the design and development of such turbines. The simulation of a complete turbine requires substantial computational resources. A specific approach that is applied to investigate the flow field of one turbine may not work for another turbine. A ...

A new method for the simulation of gas turbine fuel systems based on an inter-component volume method has been developed in this study. It is able to simulate the performance behaviour of each of the hydraulic components including pumps, valves, metering unit, etc. of a fuel system using physics-based models, which potentially offers more accurate results compared with those using transfer func...

At low flow rate operation, Francis turbines feature a cavitating vortex rope in the draft tube resulting from the swirling flow of the runner outlet. The unsteady pressure field related to the precession of the vortex rope induces plane wave propagating in the entire hydraulic system. The frequency of the vortex rope precession being comprised between 0.2 and 0.4 times the turbine rotational s...

Renewable energy is derived from natural processes that are replenished constantly. Included in the definition is electricity and heat generated from solar, wind, ocean, hydropower, biomass, geothermal resources, and bio-fuels and hydrogen derived from renewable resources. Each of these sources has unique characteristics which influence how and where they are used. This paper presents the model...

This paper studies the stability comparison of four controllers for a hydraulic turbine fractional order interval parameter time-delay system. Considering terms uncertainty and time-lag, system is established by using calculus identification technology. Through edge theorem D-decomposition method, calculation process controller region derived in every detail. Subsequently, different including P...

Based on an analysis of the working principles of the hydraulic variable pitch system of a wind turbine, a novel Petri net model and reliability evaluation method are proposed. First, Petri net theory is adopted to build a model for each discrete state of the operation of the hydraulic pitch system of the wind turbine and at the same time a fault Petri net model is established. Then through qua...

The efficiency test is an important indicator to evaluate the energy conversion performance of a hydraulic turbine. For hydropower stations which do not have the direct flow measurement conditions, whether the characteristic curve of a turbine obtained through similarity theory conversion by using the comprehensive characteristic curve of the turbine can correctly reflect the operating performa...