1 results about "Voltage polarity" patented technology

The invention discloses a multi-terminal flexible DC network longitudinal protection method and system based on current limiting inductor voltage polarity, which comprises the following steps: collecting voltage values of current limiting inductor at both ends of a DC line in real time; detecting voltage values of current limiting inductor at both ends of the DC line in real time; Voltage gradientalgorithm is used to deal with the voltage, and then to detect whether there is a fault; After the protection is started, the current-limiting inductor voltage in the sampling data window is integrated, and the current-limiting inductor voltage polarity is judged by comparing the integrated value S with the set threshold value. The current limiting inductor voltage polarity R at both ends of theline is compared, and if both polarities are positive, the fault is judged to be in-area fault, otherwise, the fault is judged to be out-of-area fault. The protection principle and algorithm of the invention are simple, and do not need mathematical tools such as fast Fourier transform, wavelet transform and the like for frequency division or traveling wave capture, and also do not need data synchronization at both ends of the line, and are easy to realize. The data window of the protection criterion is short, and no additional fault pole identification step is needed, so the protection criterion is fast.