Proper Grid Voltage Control For Distribution System With High Solar PV Integration

A properly utilized solar energy system can offer numerous benefits to both the customer and the eco system. But integrating large number of solar PV systems into the distribution network, can cause considerable effects on power flow stability and power quality. When more solar Photovoltaic is connected to a distribution grid, in day time, the solar penetration is high while the load is less. Then the terminal voltage tends to increase. This rise in voltage causes inverter tripping in the solar PV systems that affects the generation in the power system. Therefore, it requires a proper voltage control methodology at the distribution level. The voltage level can be maintained in between the desired standard levels by controlling reactive power injection. Though the power industry employs voltage controlling devices such as OLTCs and FACTS devises like SVC, STATCOM to maintain the grid voltage at the transmission level, they are not much used at the distribution level. Whenever the problem occurs, operator manually turn on the inverters. According to the details collected with reference to the distribution system in Northern Province Sri Lanka, a low voltage distribution system was modelled using PSCAD simulation, in order to overcome the stated problems. The aim of this model is to study the terminal voltage variation in the distribution grid with large number of solar PV connections and to restore the voltage levels again to the standard limits by applying different voltage control techniques. The study proposes two solutions, SVC and STATCOM to improve the performance of the power system. More economical and efficient method among two proposed solutions was validated using the simulation results. Net Present Value (NPV) method was used to provide proper economic analysis, related to the solution given, based on the simulation results.