Because of this anomaly, the protection mechanism of the wind turbine was triggered, resulting in many wind turbines tripping and leaving the grid, which in turn caused the current in the grid to exhibit an attenuation trend. After taking emergency measures such as shutting down some wind turbines, the entire system gradually returned to a stable state [7]. In 2016, Tongyu County, Baicheng City, Jilin Province repeatedly encountered SSO phenomena with frequencies of approximately 5 Hz, but these phenomena disappeared when the related series compensation system was turned off [8]. After much research, scholars have divided SSO into the following three types according to its causes: sub-synchronous resonance (SSR), sub-synchronous torsional interaction (SSTI), and sub-synchronous control interaction (SSCI). Ref. [9] proposed that with an increase in the series compensation, the minimum value of the equivalent resistance further decreases, the natural resonant frequency of the system increases, and the danger area of the DFIG effect moves to the high-wind-speed region and becomes more intense. Ref. [10] illustrated that when the equivalent electrical negative damping of the system is greater than the sum of the equivalent positive damping of the stator and transmission systems, the output power diverges and oscillates. Ref. [11] pointed out that the SSO caused by the device is mainly studied in the field of thermal power units, and there are few studies on wind power, because this problem has not been encountered in actual engineering. Ref. [12] summarized the mechanism of SSCI and the influence of the controller and system parameters on SSCI and summarized the research methods and main inhibitory measures of SSCI. Ref. [13] revealed that the interaction between wind turbines and the series compensation system is the key factor that triggers SSO, and further studies have found that the negative damping characteristics of DFIG at sub-synchronous frequencies are the main reason for SSCI. The analysis results show that the oscillation frequency of the wind turbines changes continuously with time, the grid operation mode, and the number of generators. References [10;11] investigated the influencing factors of SSO. In this paper, a model was built in Simulink and experiments were conducted to verify the impact of external operating conditions on SSO. On the basis of the former theory, this paper further validated the influence of the proportional coefficients of the outer loops of the rotor-side converter (RSC) and the grid-side converter (GSC) on SSO, discovering that a larger proportional coefficient in the outer loops intensifies SSO. Ref. [14] proposed a control method for attaching a virtual impedance to the rotor-side converter of a doubly fed wind turbine, where the real part of the virtual impedance improves the damping characteristics of the system and thus suppresses the SSO. Ref. [15] proposed a sub-synchronous virtual resistance strategy, which plays the role of increasing the sub-synchronous oscillation damping and suppressing the oscillations by introducing a virtual resistance in the sub-synchronous frequency band in the control of the wind turbine motor side, which can be physically interpreted as a series of virtual resistors in the rotor circuit of the motor. Ref. [16] designed an additional power-controlled sub-synchronous damping controller and provided a strategy for tuning the parameters of this controller to optimize its performance. Ref. [17] proposed a damping controller design method that is more adaptive than the traditional damping controller, which is mainly based on a self-immobilizing controller that can effectively inhibit the SSO phenomenon in a doubly fed wind power system under different operating conditions and improve the stability of the system. Ref.