632 / 2019-04-10 09:37:06

A new protection principle of Modular Multilevel Converter Based High Voltage Direct Current transimission lines using series inductance voltage of one-end converter

MMC-HVDC；fault analysis；relay protection；PSCAD, series inductance voltage

Modular Multilevel Converter Based High Voltage Direct Current (MMC-HVDC) technology has been developed rapidly. However, the fault of DC line is the key problem of the safe operation of MMC-HVDC transmission system. In engineering practice, series small inductance is installed at both ends of MMC-HVDC transmission line, which creates favorable conditions to solve the problem of DC line fault in MMC-HVDC transmission system. In this paper, characteristics of various short-circuit faults that may occur on the DC line of MMC-HVDC system are analyzed firstly. According to analysis result, it is obtained that the polarity of the series inductance voltage is differrent and the change rate of the fault component of the series inductance voltage is also different when fault occurs on the DC line or not. According to these characteristics, a new protection principle of MMC-HVDC transmission line using series inductance voltage at one-end converter is proposed. The protection principle is implemented by using the change rate of the fault component of the series inductance voltage to identify fault type which is internal fault or external fault, and the polarity of the fault component of the series inductance voltage to distinguish fault pole. Finally, a two-terminal MMC-HVDC simulation model is built in PSCAD/EMTDC, and the protection algorithm is verified by MATLAB. Simulation results showed that the proposed protection principle was correct.
This work is supported by Key support projects of the National Natural Science Foundation(U1766209) and National Natural Science Foundation of China (No. 51777166).