Research On Application Of Integrated Relay Protection In Low And Medium Voltage Substation

The current relay protection device is discrete functional and mutually independent .It only collects single-point information without making judgment globally, thus unable to satisfy steady operation requirements of the complex power system. Therefore, scheme of integrated relay protection for whole transformer substation has been proposed in this paper. This scheme sets out the new constitution mechanism of protection based on the whole electricity information of the substation, rather than assembly of the original protection schemes.In the case of compound voltage starting over-current protection for the traditional transformer, when fault occurs at low voltage side, sensitivity of the protection is often affected due to unapparent voltage drop of the high side. Scheme of transformer integrated protection based on directional element is proposed in this article to solve this problem. In this scheme, divisional differential protection,which is the main protection,is made by connecting the CT of transformer winding sides and feeder line sides longitudinally. With information of the directional element and fault location, the relation matrix which sets particular trip logic is made as the phase-to-phase fault backup protection. The problems in compound voltage starting over-current protection are solved in the scheme, associated with the advantages of sensitivity enhancement and protection time reduction.To solve the problem of 50% reliability of traditional zero sequence protection selective tripping scheme, the grounding protection scheme for transformers based on zero sequence directional elements is designed in the paper. The relation matrix of directional element and fault location's information is made to set up the trip logic. It avoids the whole substation power outage when the failure occurred on the grounding transformer side. Furthermore, this trip logic would distinguish the line side fault and transformer grounding side fault.In this paper, scheme of bf protection based on the multi-AGENT system is proposed. The start-up circuit and locking circuit are assigned to specific responsible AGENT; and the lock removing circuit is omitted. The scheme features on-line value adjustments, it significantly improves the reliability and sensitivity of protection.Finally, the key problem of realizing of integrated protection, such as hardware platform, protocol of IEC61850, multi-agent technology, is discussed. And lateral comparison of integrated protection, wide area protection and area protection is carried out.