Grid power quality improvements using grid-coupled hybrid electric vehicles

TLDR: The interaction between grid-coupled full hybrid electric vehicles (HEV) and the grid allows the hybrid vehicle to travel a significant part of the time in all-electric mode and enables a lower energy cost and a reduction in environmental pollution, on condition that the electric energy production itself is environmently friendly.

Abstract: The paper examines the interaction between grid-coupled full hybrid electric vehicles (HEV) and the grid. The interaction allows the hybrid vehicle to travel a significant part of the time in all-electric mode. On the other hand, the grid coupling allows the grid to use the hybrid car as a controllable load and energy storage facility, enabling a higher penetration of variable generation units, such as renewable sources based on wind and photovoltaic cells. Experiments with a battery, grid connection and induction machine prove the feasibility of these grid-coupled hybrid electric vehicles. 1 Introduction The batteries currently used in HEVs are expensive and heavy, leading to a low specific energy content. Through the rapid development of batteries the cost per kWh diminishes while the specific energy content rises. As a consequence, larger amounts of energy can be stored in an economic way for the electric propulsion of HEVs and larger distances can be travelled in an all-electric “emission free” mode. An estimated 85 % of fuel (not energy) savings can be achieved if the vehicle has an all-electric driving range of 100 km [6]. In order to achieve this kind of fuel savings, the battery needs to be charged with electrical energy from the grid, as opposed to the current practice where a combustion engine powers an on-board electric generator to produce electric energy. The only requirement to make this happen is a grid coupling. This grid coupling makes a variety of interactions possible between a fleet of HEVs and the grid [1,5]. From the perspective of the hybrid fleet, the grid coupling enables a lower energy cost and a reduction in environmental pollution, on condition that the electric energy production itself is environmently friendly. From the perspective of the grid the fleet of hybrid electric vehicles can act as a controllable load to smooth grid load. Power electronics for the grid coupling, can provide reactive power to enhance the power factor of the installation and can be used as an active filter to eliminate harmonics. By injecting electrical energy in the grid, the HEV can be used as reserve power unit to set off the loss of a power plant, as replacement for peak power units, as part of a microgrid or as stand-alone mobile generator. Other possibilities such as peak-shaving are possible from a technical point of view, but lack the necessary economical feasibility.