Method and device suitable for locating grounding fault of photovoltaic-field DC cable

Method and device suitable for locating a grounding fault of a photovoltaic-field DC cable. The method comprises the following steps that 1) power loss P of a unit length under the condition that the DC cable has no fault is obtained; 2) power P1 and power P2 of the two ends of the DC cable with a fault are calculated via voltage and current, P1 represents power of the end close to a power supply, power loss P0=P1-P2 of the DC cable is calculated, and the rated power loss P =P *L of the DC cable is calculated according to the length L of the DC cable; and 3) P0 is compared with P , if P0>=P , the DC cable is normal, and if P0 is lower than p , the DC cable has a fault, and the distance L0 between a fault point to the power end of the DC cable equals P0/P . According to the method, the position of the fault point is determined by measuring current and voltage of the two ends of the DC cable, and compared with a traditional method, the method of the invention is simpler and is convenient to master by technical staff, the fault position of the DC cable can be obtained rapidly in real time, and time to handle with a DC fault accident is shortened.