For improving the stability of flexible HVDC transmission system

auxiliary direct voltage rings are usually installed on the inverting side of flexible DC unit. When the DC voltage between positive and negative poles drops to a certain threshold

the DC voltage is controlled by the inverting side

while the rectifying side transmits the fixed active power and provides reactive power support for the AC system voltage. However

due to the influence of either environment or quality itself

HVDC voltage divider may generate fault and lead to DC voltage fluctuation. In case of abnormal high of the measurement of the rectifying side

the auxiliary direct voltage loop on the inverter side acts which

at this time

causes the both ends of rectifying and converting side of the system to control DC voltage

the transmission power of DC system is out of control and even reversal. In view of this risk

based on RTDS asynchronous networking simulation platform

the abnormal measurement of DC voltage and current is simulated by way of the measurement value multiplying an abnormal coefficient k.The mechanism of power inversion caused by high DC voltage measurement is analyzed

and the corresponding preventive measures are proposed.