Analysis of Subsynchronous Oscillation Mechanism and Its Influencing Factors in Large-scale Photovoltaic Series Compensation System

With the rapid development of new energy power generation, the installed capacity of photovoltaic power generation continues to increase in the proportion of power supply in the power system. In order to realize large-scale long-distance transmission of photovoltaic power generation, it is planned to adopt series compensation capacitor (hereinafter referred to as “series compensation”) transmission technology to transmit large-scale photovoltaic power generation to the load center. However, there is a risk of inducing subsynchronous oscillation in the dynamic interaction between series compensation line and photovoltaic grid connected inverter. The specific mechanism of sub synchronous oscillation in the interaction between series compensation line and photovoltaic grid connected inverter has not been clear. In order to ensure the stable operation of large-scale photovoltaic power generation bases, it is urgent to reveal the specific mechanism of sub synchronous oscillation of the interaction between large-scale photovoltaic power generation and series compensation lines. In view of the above problems, this paper applies the small signal analysis method and time-domain simulation analysis method to study the mechanism of sub synchronous oscillation of large-scale photovoltaic and series compensation lines, and carries out simulation verification. Finally, the equivalent model of photo voltaic power station is built in PSCAD/EMTDC platform, and its accuracy is verified by simulation.