Research On Grounding Protection Of Neutral Non-Effective Grounding System Based On Smart Substation

Single-phase grounding fault is the most common fault type in distribution network. At present, there are a lot of single-phase grounding protection principles, and most of them determine the fault line by collecting single slip fault information. From the use effect, the reliability, selectivity and applicability in neutral grounding has not been approved by users. The smart substation based on networking and digital communications platform, provides a new technical means to solve single-phase grounding protection in distribution network.The technical specifications of State Grid recommend that the smart substation in distribution network is constructed as “two layers and a network” structure, and there is no process layer network to share analog data. Based on the “two layers and a network” smart substation, adopting smart substation information sharing technology to share information via GOOSE to achieve network-based relay protection is proposed. Based on the analysis of basic steady-state principles and limitations of common single-phase grounding protection principles, principle of zero sequence full current group power direction is adopted as single-phase grounding protection principles, and the correctness is verified by PSCAD. O n this basis, new single-phase grounding protection algorithm based on GOOSE is constructed by the fault identification matrix, and the algorithm accuracy is verified by simulation example in PSCAD. Take a typical mining industry power supply system as an example, build the power network simulation model in OPNET software and verify the real-time of network-based relay protection. Analyze the impacts of factors on the network in real-time and discuss methods to improve the network real- time. Finally, the smart substatio n grounding protection software is designed including the software’s anti-interference measures.