Grid-side voltage measurement abnormity judgment device, flexible direct current system and control method

The invention discloses a grid-side voltage measurement anomaly discrimination device, a flexible direct current system and a control method, and the device comprises an electrical quantity collection module which obtains an electrical quantity signal of the flexible direct current system, and transmits a digital signal obtained through the digital-to-analog conversion of the electrical quantity signal to an algorithm control module; the electrical quantity signals comprise grid-side voltage, grid-side current, valve-side current, direct-current voltage and second measuring point grid-side voltage; and the algorithm control module receives the digital signal, carries out judgment operation on the network side voltage, and replaces the network side voltage with the network side voltage of the second measuring point when the numerical value of the network side voltage is abnormal, so as to carry out dq conversion and phase-locked loop control on the network side voltage, and further meet the closed-loop control