Identifying the factors influencing the voltage quality of 6kV grids when using electric excavators in surface mining

Abstract

Purpose. The research purpose is to study the relationship between the number of electric excavators and their impact on reducing the voltage losses. As a result of the research, it becomes possible to obtain factors that can help the manager to correctly understand the effect of power compensation caused by the over-excitation mode of electric excavators. Methods. The paper uses the Jacobian matrix transformation to simulate the power flows of electric excavators, the driving mechanisms of which are mainly synchronous motors. The input data for the simulation is the in-situ measurement data representing the inverse power flow. A diagram and a software to determine the factors corresponding to the number of electric excavators are also provided. Findings. A cross-reference table has been compiled showing the ratio of factors corresponding to the number of electric excavators in a 6kV grid. An appropriate software has also been developed, including a table for correcting typical equations for calculating voltage losses. Originality. The proposed factor is conditioned by over-excitation mode of excavators operating as compensation machines in a 6kV grid. Practical implications. When calculating the voltage loss in a 6kV grid of surface mines, if the design feeder contains electric excavators, a modified factor should be added to give a correct idea of the voltage quality.