Grid Stability Analysis for High Penetration Solar Photovoltaics

The ever growing global energy needs and the immediate need for an environment friendly sustainable growth have made us to focus on renewable energy sources, especially wind and solar. But these renewable energy resources when implemented in large scale without any specialized controls is found to impact the integrity, reliability, security and stability of the power grid. Solar PV has become the major portion among the utility level renewable energy power plants. Solar PV power penetration into the grid is on continuous rise and plants of order of hundreds of MW are coming up in India and at global level. In India, till now the utility scale solar PV installations do not follow any specialized controls for grid support and will just get disconnected when there is a grid disturbance. This will severely impact the grid when the size and scale of the solar PV plant is huge. In this paper, a brief study on the controls existing in a conventional power plant to manage grid stability has been presented, as the large upcoming utility scale solar plants are expected to behave similar to the existing conventional power plants when it comes to handing grid stability and support. Further, this paper is aimed at studying and analyzing the impact of the large scale penetration of solar PV power into the grid. The IEEE 9-bus system has been considered as a standard test bus platform for the analysis. The simulation has been performed with the help of ETAP v12.6 (Electrical Transient Analysis Program) software, which is a very suitable tool for power system simulation and analysis. This study investigates the impact of large penetration of solar PV systems on steady state performance as well as transient stability of a large power system. The steady state voltage and power loss in the system have been studied under various PV penetration levels. Also, the impact of increased solar penetration on the transient stability performance of the power system has been observed. The results have been analyzed and the observations and inferences are presented. Keywords-Large Solar PV penetration; Steady state analysis; Transient stability analysis; ETAP;