Aiming to solve the problems that the
electric power plant trips due to the ground fault for the strings under
alternating current or
direct current condition, and a plurality of accidents appear, for example, the device is damaged, the important
relay coil with easy incorrect-
tripping is connected with a shunt
resistor in parallel, the communication is carried out between the
electric devices, and a rectification, insulating and
tripping functional switch is installed on a direct-current power supply
branch circuit, so that the influence on the fault source is reduced or isolated. The invention provides a novel
direct current system design principle and a method, a special hall sensor for the unbalanced current is adopted, a
grounding resistance-
capacitance loop is increased, the unbalanced current of the grounding
branch circuit is increased, the sensitivity of measurement is improved, a distributed on-
site monitoring module finishes the
data acquisition and the
data transmission of the
busbar voltage, the unbalanced current, the on / off state, and the like, the monitoring center finishes
processing all the data and warning according to the logic of the design, the
tripping command is transmitted to the fault
branch circuit through the distributed on-
site monitoring module, and a switch with tripping function is used for shutting the fault branch circuit off in time after receiving the command. Therefore, the technical problem that the fault range is extended due to the
short circuit and the ground fault for strings under the
alternating current and the
direct current condition is solved.