Evaluation method for relay protection of flexible DC transmission system based on multi-source information of relay protection test

•Point out that the essence of the dynamic test of flexible DC protection is the protection action behavior function.•Propose the use of the MLP to fit the non-linear protection action behavior function based on protection dynamic test.•Propose to predict protection action boundary based on protection action behavior function.•Propose to guide parameter settings for subsequent protection dynamic tests based on protection action boundary.•Propose a method for correcting the protection action boundary based on newly added protection dynamic test data. Relay protection device is a key equipment to ensure the safe operation of flexible DC transmission systems, and its performance determines whether the system can respond and isolate faults in a timely and accurate manner when faults occur. To evaluate the device's performance, the protection device needs to undergo a comprehensive test before being officially put into use. In order to address the issues of poor targeting and high cost of test in the current comprehensive test of flexible DC protection, an evaluation method for relay protection of the flexible DC transmission system based on multi-source information of relay protection test is proposed for the DC side. Based on the multi-layer perceptron (MLP), the complex nonlinear mapping relationship between fault conditions and protection action behavior is fitted according to the protection test results, and the protection action boundary is predicted to guide subsequent protection tests and evaluate protection performance. Taking the traveling wave protection of a typical double-ended flexible DC transmission system as an example, the relay protection action boundary of the traveling wave protection is calculated, which verifies the feasibility of this method.