Control and Protection Strategy Study of VSC Station Fault at Hybrid HVDC Transmission System

Abstract LCC-VSC UHV hybrid cascaded DC transmission system will face over-voltage problems caused by power surplus when receiving terminal VSC station fault occurs. An over-voltage suppression strategy based on the action input of a high-voltage controllable arrester and the stepwise blocking of non-fault VSC at the receiving end is proposed, and a dynamic simulation test system is built to verify that the stepwise blocking protection scheme can effectively reduce the DC voltage stress of fault VSC by about 25.9%. Based on the test results, the effectiveness of the over-voltage suppression scheme of VSC at the receiving end in practical projects can be demonstrated by analogy.