The invention relates to a fault monitoring and protection technology for a flexible
direct current transmission system, in particular to a fault detection and polarity judgment method and
system for the flexible
direct current transmission system, and the method comprises the steps: firstly constructing a differential current and a zero-mode current through positive
electrode current and negative
electrode current, and carrying out the preprocessing through band-pass filtering; then, in the short-time detection window and the long-time confirmation window, key features of difference and
zero mode are extracted by adopting an adaptive truncation and robust statistical method, and
zero mode compensation is realized in combination with
covariance correction; and finally, through multi-scale fusion of short window and long window results, a fusion mean value and variance are calculated, a
confidence interval is constructed, and rapid fault detection of the flexible direct-current
power transmission system and accurate determination of the polarity of the positive
electrode and the negative electrode are realized. According to the method,
rapidity and robustness are taken into consideration, interference of
noise and abnormal points is effectively suppressed, rapid and accurate fault identification of the flexible
direct current system can be realized in a complex operation environment, and
technical support is provided for
operation safety and protection control of a flexible direct current
power grid.