Small-signal Dynamic Modeling and Stability Analysis of Integrated Systems with Photovoltaic and Hydropower Stations

The integrated systems with photovoltaic (PV) and hydropower stations can effectively compensate for the fluctuant output power of independent PV generations. However, hydropower stations are mostly located in remote areas, and they are connected to the grid by weak connections. The small-signal stability problem severely limits the power supply of integrated systems. In this paper, a small-signal dynamic model suitable for integrated systems is established by considering detailed models of PV and hydropower stations. Based on the constructed model, a comprehensive small-signal stability analysis is performed. The impact of (i) PV dynamics, including DC voltage controller, AC current controller as well as PLL, (ii) PV locations, and (iii) PV capacities on the local and inter-area electromechanical oscillation modes is analyzed. Finally, time-domain simulation in PSCAD/EMTDC and Prony analysis validate the effectiveness and accuracy of the stability assessment results.