Research on DC Transmission Operation System Based on Analyze the Principle of Udi0

When Udi0 reaches a fixed value and continues for a set time, it will lead to the tap monitoring tripping in the pole- controlled backup protection, or the monitoring system will start blocking due to the valve arrester bears too high voltage. The first pole of the converter station sends out Udi0 alarm for many times. The preliminary analysis that it is caused disturbance by the tap position signal input into the loop of the extreme control system, but the real reason has not been found. At present, it can but exit its Udi0 tripping function. We will analyze the Udi0 alarm and trip of principle, to find the cause of Udi0 alarm, and the design of IR filter module to filter and change the pole control valve side voltage Udi0 calculation logic of these two kinds of methods to avoid a false Udi0 alarm, at the same time to program software implementation of the second method and simulated experiment, verified the feasibility of the countermeasures. It is determined that there is an abnormal signal in the tap position of the commutator ,and switch other tap position signals to participate in calculation ,so that the monitoring function of the taps joint of the commutator and the overvoltage monitoring function of the valve arrester can be permanently effective rather than shielding. The scheme is verified by RTDS simulation, and the expected effect is achieved.