: In this work, A STATCOM of 12-pulse two levels is used to regulate the bus voltage at specific bus bar under many cases of abnormal conditions like load and source disturbances. The proposed system consists of a single machine, transmission line and load. The compensation process are performed and compared between the two suggested control methods, first, the conventional control by using PI controller only which is used to improve the voltage profile. Second, the adapting controller uses self-tuning fuzzy PI controller for improving the voltage profile. At the time of disturbance gets occurrence, the PI controller must change its parameters to recover the voltage profile into the stable state at the disturbance moment. The simulation results show the improvements of voltage profile for both two types and then compare them. The improvement of voltage profile using adaptation method is less over shoot and attains a steady state faster than the conventional PI when the system is subjected under many disturbances. The results of the harmonic effect show low values of total harmonic distortion (THD) of supply voltage and current. Moreover, it is acceptable with IEEE standards because a new technique of Sinusoidal Pulse Width Modulation (SPWM) is used.