Jiangsu Electric Power achieves accurate positioning of single-phase grounding faults using multi-source data

"The arc grounding test is completed, showing that the fault line on site is the 10kV Dongzhuang Line 1, and the fault section is between pole 40 and pole 15 of Shadong Village Branch Line 5. I hereby report this." On the afternoon of May 21, as the person in charge of the on-site main station reported, the State Grid Jiangsu Electric Power Company successfully verified the single-phase grounding fault judgment based on multi-source data. This means that the company is the first in the State Grid system to achieve accurate judgment of small current single-phase grounding faults based on multi-source data.

For a long time, after a single-phase grounding fault occurred in the 10kV outgoing line of the substation, the distribution network controller could not accurately determine which line the grounding fault was on. "Before, the only way was to use the 'pulling line method'. The distribution network controller checked the 10kV outgoing lines of the substation one by one through the D5000 system, which was not only time-consuming and laborious, but also might cause short-term power outages on non-faulty lines, affecting customers' electricity experience." said Yang Zijun, deputy director of the Comprehensive Technology Department of Jiangsu Electric Power Dispatching and Control Center.

To this end, Jiangsu Electric Power launched a pilot project in Yangzhou in 2018. Yangzhou Power Supply Company and Jiangsu Electric Power Research Institute established a scientific research team to develop a scientific and technological project called "Research and Demonstration Application of Efficient Fault Location Technology for Distribution Networks Based on Multi-source Information" in order to achieve accurate location of single-phase grounding faults. This experiment is to verify the project content on site.

According to Yang Jinxi, deputy director of the dispatching center of Yangzhou Power Supply Company, this test selected Yangzhou 110 kV Longquan Substation. By using the single-phase grounding test equipment on the 10 kV outgoing line "Dongzhuang Line 1" of the substation to generate a real single-phase grounding fault signal, it was verified whether the multi-source data small current grounding fault diagnosis system can accurately determine the location of the fault signal. This test includes five types of tests: metallic direct grounding, 250 ohm transition resistance grounding, 500 ohm transition resistance grounding, 1000 ohm transition resistance grounding, and arc grounding, which basically covers the types of single-phase grounding faults that may be encountered during actual operation. Relying on the on-site small current grounding fault line selection device, the new generation of fault indicators and traveling wave fault location devices, as well as the big data analysis platform based on the fault location algorithm of multi-source information and the new generation of single-phase grounding fault analysis module of the distribution main station, the fault is accurately located, which is the first time in the State Grid system.

Based on the investigation of the performance and functions of existing distribution network equipment and communication conditions, the joint research team made comprehensive use of the latest devices and technologies to build a single-phase grounding fault analysis system integrating "cloud", "pipe" and "end", realizing ubiquitous Internet of Things for distribution network control and operation management.

"The collected data are uploaded to the single-phase grounding fault analysis system through the 4G wireless private network. After automatic analysis and judgment by the big data analysis platform based on the fault location algorithm of multi-source information, the distribution network controllers can be informed of the single-phase grounding fault in the first time, and simultaneously and accurately and quickly judge the faulty lines and sections. The whole process is completed automatically and takes only 1 minute." said Bu Qiangsheng, deputy director of the Relay Protection Office of Jiangsu Electric Power Research Institute.

It is understood that this approach can achieve efficient positioning of small current grounding faults, avoid power outages caused by manual line pulling, and improve power supply reliability.

(Huang Lei and Wang Shengbo)