Investigating SSO risks of large‐scale photovoltaic generation with the series compensated transmission lines

Abstract

With the increasing of photovoltaic (PV) installed capacity, large-scaled development of PV and centralized grid connection has become an important form of solar energy resources utilization. The series compensated transmission lines could enhance the long-distance transmission capacity of large-scale PV plants. Some PV plants in China are planned to adopt this technology. However, series capacitor compensation transmission lines are one of important sources of sub-synchronous oscillation (SSO). This SSO risk is a potential threat for the operation of PV plants and the stability of the utility grid. It is urgent to investigate the SSO risk of large-scale PV generation with the series compensated transmission lines. This study first developed a dynamic model of large-scale PV generation connected to the utility grid with series compensated lines on PSCAD platform. The PV dynamic model is built with detailed circuits of the power converter. Using the proposed model, the interaction of PV inverter control parameters, reactive power compensation device and the series compensation degree is investigated in detail. Then, the dominant parameters that affect the SSO are identified. From the results above, the SSO damping expression is deduced to reveal the SSO performance of large-scale PV generation with series compensated transmission lines.