An Improved Transformer Protection Scheme Based on Integrated Protection System

In recent years, there have been the rapid developments in microprocessor technology. Digital technique is believed to be the one of the most important techniques for modern power systems since later 1960s. The progresses in microprocessor, communication and transducer technologies have provided new means for the design and development of new generation of algorithms and devices in power system. The development of its high-speed communication network in real-time system and the implementation of the IEC61850 standard have made the construction of Integrated Protection system possible. The Integrated Protection is used to denote the integration of protective devices for multiple power apparatuses within the substation into one protective relay. Based on digital substation, Integrated Protection has much more advantages on control and protection. Studies show that the protective relay can derive many new and advanced strategies if it obtains enough real-time information from multiple protected equipments. Comparing with the existing traditional protective relays which are based on protecting individual equipment, the integrated protection system has more advantages and a brighter developing prospect. Integrated power transformer protection is one part of the substation integrated protection scheme. Recently, the correct operation percentage of transformer protection is relative low, which is far less than the line protection and generator protection. The existing transformer protections haven't filled the demand of the power system. The requirement for improving performance of transformer protection relay becomes stronger. Studies have found that the fault generated electric quantities can not only be detected by integrated relay to achieve the line protection but also used for developing transformer protection techniques. With the cooperation between different protection functions, integrated power transformer protection can quicken up the pace of back up protection. Based on the line protection, integrated protection can increase the reliability level of the transformer protection.