UBC Theses and Dissertations
Impact of photovoltaic generators and electric vehicles on a weak low voltage distribution grid Gudivada, Venkata Thulasi Prasad
In this thesis, the behaviour of a weak power distribution grid at the Point of Common Coupling (PCC) in the presence of a Photovoltaic (PV) inverter and Electric Vehicles (EV) as loads is analyzed. The grid connected to PV and EV has high impedance. The impact at PCC when the injected power varies in conjunction with the frequency and voltage deviation with a delay in inverter fed power is elaborated. Various measures such as peak shaving, coordinated charging, voltage drop correction have already been developed to mitigate the impact at PCC. These measures are observed on a combined EV and PV setup. In general, the grid tied inverter injects power based on an average grid voltage calculation at stable synchronization with the grid. If an error (for instance, an error in average grid voltage calculation) persists in such a case causing a loss in synchronization between the PV inverter and the grid, then a delay in the power injected may result in an oscillation at the PCC. A simple two bus system is considered to analyze the result of transportation delay. The delay and droop parameters of the PV inverter are altered whose results are quantitatively analyzed. The model abides the grid codes for active power reduction and static voltage support requirements. Further, the impact of a fault along with an inverter delay is analyzed. Simulative analysis is performed in the DIgSILENT PowerFactory software. To reduce the impact at PCC, performance criteria are analyzed whose parameters could be measured and altered. Scenarios are developed to analyze EV‟s impact in the presence and absence of storage and Distributed Generator (DG) that can be extended onto the micro grids.
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