Analysis of Sub-synchronous Oscillation Disturbance Path and Damping Characteristics of Photovoltaic Incorporated into Weak AC Power Grid

In photovoltaic power station integrated with weak AC power grid, the interaction between photovoltaic inverter control system and power grid impedance characteristics may lead to secondary synchronous oscillation (SSO) accident, which threatens the safe and stable operation of power grid. However, the disturbance paths within the system are rarely involved in the existing studies, which cannot further reveal the sub-synchronous interaction between the systems. To solve the above problems, this paper adopted a method combining closed-loop transfer function block diagram with damping torque method, deduced the SSO disturbance path, carried out the damping torque analysis of the disturbance path, and studied the influence of system parameters on the DC capacity-dominated SSO mode damping.The research results can provide a theoretical reference for the parameter design and damping controller design of photovoltaic power station in practical engineering.