Modelled Research to Reduce Frequency Fluctuations for Grid Tied PV in IEEE 9 Bus System: A Variable Droop-Controlled Analysis

Penetration of large-scale grid-tied photovoltaic power station to the grid unstable the frequency of the system due to variance in irradiance of solar energy and hence the generated power. This paper aims to provide a robust method to reduce the frequency fluctuations using droop controller along with the integration of battery energy storage system (BESS) and capacitor bank (CB). The whole system has been simulated for IEEE 9-bus multi-machine grid system where the BESS provides necessary inclusion to the power generated by the 10MW PV system. The droop controller has been designed in such a way that it takes the error signal of frequency comparing 50 HZ and incorporates dead-band with variable gain for lowering the frequency fluctuations. The whole system is designed and tested in PSCAD/EMTDC, an industry standard software platform for power system electromagnetic transient simulations, to prove the functionality of the proposed system. The simulated results prove the effectiveness of the variable droop control strategy to reduce the frequency fluctuations of entire grid due to the inclusion of PV power stations to the grid system.