Convertible static synchronous compensator

The invention provides a convertible static synchronous compensator. The convertible static synchronous compensator comprises at least one parallel transformer, a current converter, a switching loop and at least one series transformer. At least one side of each series transformer is connected with at least one bypass switch in parallel. The alternating-current side of the current converter is connected to the parallel transformers through the switching loop and then connected into an alternating-current system. The alternating-current side of the current converter is connected with the series transformers through the switching circuit, and the series transformers are connected into a line in series. Two operation modes of the static synchronous compensator and a static synchronous series compensator can be achieved through the structure, and the convertible static synchronous compensator has excellent economy and flexibility.