Abstract：When an inter-stage short circuit fault occurs in a cable aggregation line, the rapidly rising inrush current will cause the converter to block in a very short period of time, resulting in a prolonged loss of power in the system. Incipient faults are the minute breakdown stage before a short-circuit occurs in a DC cable line, which are sure sign of short-circuit failure. Incipient faults in the line can be identified and isolated in advance through active protection, which can significantly reduce the risk of short-circuit inrush currents leading to indiscriminate blocking of converter equipment throughout the network. The characteristics of incipient fault electrical quantities are weak, and it is difficult to support the protection criterion alone. And the thermal power of the arc accompanying the fault is large, which will bring significant temperature characteristics. However, it is difficult to guarantee the action speed only depending on the temperature criterion, and the incipient fault may develop into a short-circuit, so it is necessary to research new incipient fault detection algorithms. To address this problem, this paper establishes an electric-thermal characteristic analysis model for incipient faults of cable lines, analyse the characteristics of arc power in the electromagnetic field , radial propagation properties of arc energy in the temperature field and comprehensively analyse the interaction properties of the electromagnetic and temperature fields of incipient faults, revealing that the arc energy, as a coupling quantity connecting the electromagnetic field and the temperature field, has an essential difference before and after the fault. To break through the bottleneck of the existing feature quantity extraction methods, a calculation method of arc energy based on current and temperature is designed. Make use of the distributed temperature sensing(DTS)to measure the operating temperature of the whole cable, extract the arc energy features by particle swarm algorithm using the line operating temperature and differential current calculation, and an active protection criterion is formed. The active protection process is after the start-up criterion is satisfied, initiate double-ended communication and DTS, collect differential current and line temperature data within 40s, and substitute into incipient fault detection criteria, if a branch is satisfied, a command is sent to the load switch for that branch to isolate. In order to verify the validity of the active protection principle proposed in this paper, joint simulations in PSCAD and COMSOL, as well as artificial simulation tests in the laboratory were carried out. Simulation and experimental results show that this method can reliably identify and isolate the faulted section using the load switch within the shortest duration of the incipient fault, and has good applicability under different fault conditions and field conditions, and have a certain degree of noise resistance. Compared with the existing methods, the method in this paper reduces the probability of false rejection and improves reliability which can significantly reduce the probability of short-circuit faults, and ensures safe and efficient operation of large-scale DC collection systems. Provide optional ideas for the protection challenges that have always been associated with DC pooled delivery systems.
贾科, 李昱霖, 毕天姝, 张旸, 陈帅. 基于早期故障判别的直流并网系统主动保护[J]. 电工技术学报, 2025, 40(5): 1427-1439.
Jia Ke, Li Yulin, Bi Tianshu, Zhang Yang, Chen Shuai. Incipient Fault Identification Based Active Protection of DC Collection Line. Transactions of China Electrotechnical Society, 2025, 40(5): 1427-1439.
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2025, Vol. 40 
