Overvoltage protection system for direct-current bus of control winding of magnetically controlled paralleling reactor

The invention discloses an overvoltage protection system for a direct-current bus of a control winding of a magnetically controlled paralleling reactor. The paralleling reactor is arranged between a three-phase bridge rectifier and an MCSR control winding DC bus, and comprises a first overvoltage branch and a second overvoltage branch; the first overvoltage branch and the second overvoltage branchare sequentially connected to the output end of the three-phase bridge rectifier in parallel; the first overvoltage branch comprises a parallel module; the second overvoltage branch comprises two parallel modules which are connected in series; and the connecting point of the two parallel modules is grounded; the parallel module is formed by connecting m + n branches in parallel; each of the m branches is connected with a second resistor, and each of the n branches is connected with a third resistor, wherein m and n are integers greater than or equal to 1; and the values of m and n of the parallel module in the first