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The Indian Institute of Technology, Guwahati has developed optimised control systems for active power distribution networks. These schemes can allow the coordinated operation of electric vehicle charging stations and photovoltaic power generators.
This research was published in the journal ‘Sustainable Energy, Grids and Networks’. It will regulate the voltages generated intermittently by PV systems and allow electric vehicles to take part in the active power distribution scheme.
Officials say that electric vehicles are increasingly being considered the solution for carbon emissions in the transportation sector. EVs can be more sustainable if they are charged with renewable energy like solar energy. The problem with voltage fluctuations in power distribution networks is that solar energy is not always reliable.
“EV charging is uncoordinated at present, which leads to under-voltage of the distribution networks, and associated efficiency loss, they said. A coordinated control approach for the power distribution system is required in order to derive maximum benefits from renewable power generation and electric vehicle power sourcing. PV and EV inverters need to work in coordination with other Voltage Regulating Devices (VRD) to regulate the system voltages,” said Sanjib Ganguly, Associate Professor, Department of Electronics and Electrical Engineering (EEE), IIT Guwahati.
“We have developed an optimisation-based coordinated voltage control approach of power distribution networks to mitigate the overvoltage and under-voltage problems due to high PV generation and high EV charging, respectively. The research team has developed a three-stage model predictive control (MPC) approach to schedule charging of EVs and other devices,” he added.
IIT Guwahati’s approach also offers a framework to transition from passive power distribution into active. Both solar power generation, as well as EV, can be used to enable power distribution to change from a passive (unidirectional flow power from the grid to consumer) to an active state with bidirectional power flow from grid to point of use and vice versa.
“Our three-stage model helps in maintaining bus voltage magnitudes and state-of-charge (SOC) of EV battery within safe limits with minimal usage of control resources and cost of electricity consumption,” said research scholar Arunima Dutta.
“For example, while the grid-to-vehicle (G2V) model is pretty straightforward, wherein a vehicle is charged by power supplied by a grid, the reverse-vehicle-to-grid (V2G) enables energy to be pushed back to the power grid from the battery of an electric car.”
“The model developed by us provides a framework of optimal G2V and V2G operation of EVs by keeping the voltages of each node of a distribution network within allowable upper and lower limits. The charging/discharging of EVs is optimally scheduled with respect to the real-time electricity pricing,” said another researcher Chandan Kumar.