Small Distribution Grid Research Articles

The Usage of the Power Load as a Physical Diagram for Electric Vehicle Charging Modelling

The development of electric vehicles (EVs) brings a lot of new problems from the point of view of the electrical grid. Electric vehicles (EV) charging causes an impact load on the distribution grid, which is often non-symmetrical, and can reach high levels in relevant parts of the grid. This leads to deterioration of the electrical energy parameters, mainly voltage level and its symmetry. The inverters operation in electric vehicle charging stations (EVCSs) generates harmonics, which also leads to deterioration of the voltage quality. In the case of simultaneous charging of a large number of EVs from a poorly designed distribution grid, significant losses inside conductors occur, and the service life of the distribution grid is shortened. In the paper, the authors deal with the modelling of EVCSs by using an alternative simulation tool when charging them as a power load, which consumes predefined active power with desired level and duration at supply voltage changes in the grid. Such defined load differs from a general load in its behaviour. The authors’ created load model is based on the real measured data. The behaviour of the created power load model is verified in the paper on a small distribution grid, where individual power consumers correspond to the standardized daily load diagrams of households and services. The goal of the paper is to verify the proposed power load model. The load model is used for solving active power losses in conductors of the electrical distribution lines, and mainly the levels of supplied voltage.

Renewable energy source (RES) based islanded DC microgrid with enhanced resilient control

Enhancements in the control scheme of renewable energy resources (RES) in microgrids are a growing region of research. In order to improve the resilience of the microgrids control, a distributed consensus-based control is utilized by spreading an information network across the small distribution grid. The estimated operating reference values and correction terms are relayed through this information network to converge the system response. However, information link islanding, dis-connectivity, and failure of information components may affect the load imbalance between generation source nodes and may vary in node voltages. The proposed algorithm aims to sustain the operation and stability of the microgrid by changing the control structure in the form of controllable information islands. Whereas, conventional control lacks the ability to sustain-system operation during information islanding scenario. Therefore, load sharing and voltage regulation are accomplished by utilizing through proposed secondary control. Finally, the usefulness of the proposed algorithm has been proved through comparison with existing control, mathematical analyses, case study, and simulations in MATLAB/Simpower systems.