Special condition wind power forecasting based on Gaussian process and similar historical data

Due to the variability of wind power, it is imperative to accurately and timely forecast the wind generation to enhance the flexibility and reliability of the operation and control of real-time power. Special events such as ramps, spikes are hard to predict with traditional methods using solely recently measured data. In this paper, a new Gaussian Process model with hybrid training data taken from both the local time and historic dataset is proposed and applied to make short-term predictions from 10 minutes to one hour ahead. A key idea is that the similar pattern data in history are properly selected and embedded in Gaussian Process model to make predictions. The results of the proposed algorithms are compared to those of standard Gaussian Process model and the persistence model. It is shown that the proposed method not only reduces magnitude error but also phase error.

Modelling of Organic Rankine Cycle for Waste Heat Recovery Process in Supercritical Condition

Organic Rankine Cycle (ORC) is the most commonly used method for recovering energy from small sources of heat. The investigation of the ORC in supercritical condition is a new research area as it has a potential to generate high power and thermal efficiency in a waste heat recovery system. This paper presents a steady state ORC model in supercritical condition and its simulations with a real engine’s exhaust data. The key component of ORC, evaporator, is modelled using finite volume method, modelling of all other components of the waste heat recovery system such as pump, expander and condenser are also presented. The aim of this paper is to investigate the effects of mass flow rate and evaporator outlet temperature on the efficiency of the waste heat recovery process. Additionally, the necessity of maintaining an optimum evaporator outlet temperature is also investigated. Simulation results show that modification of mass flow rate is the key to changing the operating temperature at the evaporator outlet.

Strength reduction of till under dynamic pore pressure condition

Cuttings in heavily overconsolidated clays are known to be susceptible to progressive deformation caused by creep and fatigue that usually begins at the toe of the slope. The progressive deformation leads to strength reduction with time at constant stress (or called softening) and could be accelerated by fluctuation of groundwater level associated with more extreme rainfall events predicted through climate change. The purpose of this paper is to assess the mechanism of progressive deformation due to creep and fatigue using element testing on samples of till. The samples were subjected to fully drained loading and the deviator stresses were held constant at various percentages of peak failure stress, while the pore water pressure was kept static or dynamic (fluctuating ±5 kPa) over a period of time. The results have shown that the samples experienced significant deformation even at a higher factor of safety (i.e. the failure deviator stress/deviator stress at which the pore water pressure was fluctuated) under pore water pressure dynamics.