Research On Secondary System Of Smart Substation And Its Application In Qingdao Power Grid

The scale of China's power grid has gradually expanded with the rapid development of the economic level,and the level of digitalization and intelligence has also increased.At the same time,it has also challenged the level of safe and stable operation of the power grid.State Grid has successively proposed the development strategy of building a strong smart grid and the ubiquitous power Internet of Things,making the construction of smart substations imperative.Since 2009,the first generation of smart substations has been promoted.Until 2011,when the State Grid Corporation fully implemented the construction,smart substations have made great progress.Compared with conventional digital substations,the equipment used in smart substations has more intelligent features,including electronic transformers,intelligent terminals,merge units,and integrated monitoring equipment.The SCD(substation configuration description)determine the data flow direction and reflect the logical relationship between the equipment,greatly reducing the traditional secondary wiring;smart substations cancel the cable wiring between the secondary equipment,and use optical cable and network cable to achieve sampling and tripping exit.Through the statistics of on-site operation data in recent years,smart substations have significant advantages in technologies such as system integration,structural layout,equipment application,economic and environmental protection.But some problems have also been exposed.For example,merge units and intelligent terminals are added,debugging costs are increased,and new communication technologies raise higher requirements to technical level of secondary staff.Aiming at the development and status of smart substations at home and abroad,this paper introduces the typical three-layer and two-network structure of smart substation,the format of SV message and GOOSE message,and the composition of SCL and SCD;Based on the model of relay protection in actual operation,combined with the current status of the 220 kV Gongkou smart substation in Qingdao area,the primary and secondary engineering configuration schemes and advanced applications are summarized.Aiming at the problems of the currently operating smart substation,such as independent and dispersed installation of secondary equipment,low data sharing rate,high maintenance workload in the later period,and low visualization degree,an optimized design scheme is proposed.The optimized design scheme is based on the requirements of “local collection,nearby protection,redundant measurement and control,information private network,and intelligent application”,which is put forward by the State Grid Dispatch Center.Based on the IEC61850 technical standard,the digital model is used to reduce the difficulty of the system structure,increase the degree of hardware integration and reduce the number of installed devices;reduce the degree of dependence on central switches through on-site digital conversion devices;realize visualization software logic through standardized hardware devices and normalized software models,etc,to improve secondary design,and promote the application of new equipment and new technologies,comprehensively improve the reliability and intelligence of the secondary system.At the same time,based on the experience of the second overhaul in the acceptance and commissioning process of 220 kV Gongkou Substation,two complete and feasible debugging schemes of centralized integration test technology and field test technology are summarized,and the application of these two debugging schemes in the commissioning process of smart substations is explained in detail.It has practical reference value for the acceptance and debugging work before the new station is put into operation.