The invention belongs to the field of the operation and maintenance monitoring of substation direct-current power source systems and relates to an insulation grounding fault
simulation unit. The insulation grounding fault
simulation unit comprises a main control
chip, a
voltage acquisition module, a communication module, a
bus-bar and
branch input control module, a
busbar and
branch insulation reduction and grounding control module, an alternating-current intrusion control module, a
direct current mutual intrusion control module, and a ground distributed
capacitance increasing module; the
voltage acquisition module and the communication module are both connected with the main control
chip; the
bus-bar and
branch input control module is connected with the
busbar and branch insulation reduction and grounding control module; and the
busbar and branch insulation reduction and grounding control module, the alternating-current intrusion control module, and the
direct current mutual intrusioncontrol module are connected with the main control
chip through an optocoupler isolation module. With the insulation grounding fault
simulation unit of the invention adopted, the automatic simulationof various faults of a direct-current power source can be realized, the ability of operation and maintenance personnel to check and solve problems can be improved, and the
safe operation of a substation can be ensured.