Through the study design based on a nonlinear PID control the controlled series compensation system, which does not rely on the characteristics of the controlled object model, to make up for the traditional linear PID control some shortcomings. The results of the study show that: with the traditional PID control based on linear fixed series compensation system in comparison, based on nonlinear PID control controllable series compensation technology, because in the feedback of the nonlinear combination to make full use of the function, strengthen the system damping, improve the system of the transient stability, and the system robustness and adaptability of has also improved.