Voltage Quality Improvement using a Series Connected Photovoltaic Distributed Generator System

The need for sustainable energy solutions to preserve the fossil fuels for future generations has been a major area of concern due to rising issues like global warming and the depletion of fossil fuel reserves. Photovoltaic (PV) distributed generations integrated into the grid systems has seen a significant growth in the recent years. Introduction of distributed energy resources like solar energy onto the distribution grid has led to increase in voltage quality problems or voltage irregularities on the distribution grid due to its highly nonlinear characteristics[2]. As the proportion of the PV generation increases, several technical challenges occur like the impact of the generators on voltage quality as the solar insulation level is weather dependent and variable. Unless suitable design feature is built for the generators, the injected time-varying solar power could lead to unacceptable voltage quality. In order to reduce the irregularities and improve the voltage quality of the distribution grid, a Series connected Photovoltaic distributed Generator (SPVG) is proposed that not only maximizes the energy harness but also enhances the voltage quality when upstream voltage disturbances occur or when the input solar power fluctuates. If the harnessed solar power is insufficient to maintain the voltage level during an upstream voltage disturbance then the stored energy in a capacitor energy storage system (ESS) in the SPGV is used to enhance the voltage quality by maintaining the load voltage constant. A dc link capacitor energy storage system with an inverter with proper control strategy is useful in tackling the grid output irregularities and in improving the voltage quality issues. The proposed test system is modelled and simulated in MATLAB/Simulink environment along with the design and control of both dc-dc converter and dc-ac converter to study the impact of the SPVG in improving the voltage quality [1].