Model for calculation of anchor parameters fixings for vertical exploration works

It is known that effective rock hardening, as opposed to the action of tensile stresses, can be performed using anchors of various designs, depending on the specific mining and geological conditions. At the same time, there are very few publications on the calculation of roof bolting parameters for vertical shafts of different cross-sections. Therefore, in this work, a method has been developed for calculating such a support for vertical shaft shafts. Calculations were made only for the working wall, which is more dangerous in terms of fallout. Anchors are considered to work in tension when this wall is attached. For the opposite wall, such calculations are not required. Considering that here the anchors are being introduced in a direction perpendicular to the direction of bedding of rocks and they will work on a cut. In this case, the shear strength of metal and reinforced concrete anchors is 4-5 times higher than their tensile strength. The calculation method consists of methods for determining the lengths of the anchor and its locking part. In this case, the length of that part of the anchor is taken into account, which is enclosed between the base of the cone of influence of the anchor and the border of the zone of possible fallouts. The resulting formula for the length of the joint part of the anchor strongly differs from the previously known similar formulas by other authors, taking into account the effect of rock pressure, which varies with depth. Its structure contains the factor of the bedding angle with respect to the horizon and the coefficient of friction of the rock about the rock, leading to a decrease in the length of the anchor lock part. In addition, the volume of destroyed rocks in the zone of influence of the anchor is taken as the volume of the cylinder, which corresponds to the actual operating conditions of the anchor.

Dynamic Equivalent Modeling of Wind Farm Based on Dominant Variable Hierarchical Clustering Algorithm

The actual operating state of the wind turbine group is influenced by the wake effect and control mode; however, the current models cannot describe the actual operating state very well. A dynamic equivalent modeling method for a doubly fed wind power generator is proposed on the basis of ensuring the accurate description of the wind turbine group. As the clustering index, dominant variables are used in the hierarchical clustering algorithm, which are extracted by principal component analysis. Three dynamic equivalent models of 24 wind turbines are established using PSCAD software platform, which use 13 state variables, wind speed, and dominant variables as clustering indexes, respectively. Furthermore, the active power and reactive power output curves of wind farm are simulated in the case of the three-phase short-circuit fault on the system side or wind speed fluctuation, respectively. The simulation results demonstrate that it is reasonable and effective to extract slip ratio and wind turbine torque as clustering index, and the maximal relative error between the dominant variable equivalent model and 13-state-variable model is only 9.9%, which is greatly lower than that of the wind speed model, K-means clustering model, neural network model, and support vector machine model. This model is easy to implement and has wider application prospect, especially for characteristics analysis of large-scale wind farm connected to power grid.

Study on Frequency Regulation of Energy Storage for Hydropower Station

The paper firstly proposes energy storage frequency regulation for hydropower stations. Taking the actual operating hydropower station as an example, it analyzes the necessity of configuring energy storage to participate in frequency regulation for hydropower stations, and according to the hydropower station AGC regulate situation, the battery capacity of the energy storage frequency regulation system is designed, and the frequency regulation performance of the energy storage frequency regulation system at different battery capacities is analyzed. It provides reference for hydropower stations with similar needs.

A comparative study of model fitting for estimating the overall efficiency of grid-connected photovoltaic inverters

Determining the static overall efficiency of inverters is sometimes necessary for control o design purposes. As getting this information from the manufacturers’ datasheets or certified laboratories might not be always viable, this paper addresses its estimation from direct measurements under actual operating conditions. Particularly, the Sandia Inverter Model has been taken as a paradigm of methodology and adapted to deal with the available data for an office building’s photovoltaic system over the 2013- 2017 period. Two unidimensional and two bidimensional models have been selected and compared to assess their goodness of fit on three inverters of the same kind of which the system consists. The best-case scenario corresponds to an exponential curve fitting, in which the R-square value increases over 0.95, outperforming the other models.

Study of energy consumption of a hybrid vehicle in real-world conditions

The paper presents an analysis of energy consumption in a Plug-in Hybrid Electric Vehicle (PHEV) used in actual road conditions. Therefore, the paper features a comparison of the consumption of energy obtained from fuel and from energy taken from the vehicle’s batteries for each travel with a total distance of 5000 km. The instantaneous energy consumption per travelling kilometre in actual operating conditions for a combustion engine mode are within the range of 233 to 1170 Wh/km and for an electric motor mode are within the range of 135 to 420 Wh/km. The average values amount to 894 Wh/km for the combustion engine and 208 Wh/km for the electric motor. The experimental data was used to develop curves for the total energy consumption per 100km of road section travelled divided into particular engine types (combustion/electric), demonstrating a close correlation to actual operating conditions. These values were referred to the tested passenger vehicle’s approval data in a WLTP test, with the average values of 303 Wh/km and CO2 emission of 23 g/km.