The Relays Protection Scheme Of Cophase Power Supply Substation

The Co-phase Traction Power Supply System (CTPSS) applies a symmetry compensate technique with a core of negative sequence and reactive power compensation in traction substations. At the same time ,it adopts the Integrated Power Flow Controller (IPFC) to remove system unbalance, filter harmonics and compensate reactive current. the Asymmetric single-phase load system with negative sequence , harmonics and low power factor which can be regarded as a pure resistive leakage three-phase symmetrical load. The co-phase power supply substation is constructed with the important devices including traction transformer and IPFC etc. Only these core devices run normally at all the time, the CTPSS can run safely and stably.The critical point to set CTPSS substation under protection lies in traction transformer and IPFC. This thesis' transformer relay protection includes gas protection, over current protection, overvoltage protection, ground protection.also differential protection with a variety of strategys. Differential protection is the main relay protection of transformer, and it is important to recognite inrush current and internal fault current. Now there are lots of ways to recognite inrush current, such as Current Waveform Characteristics Recognition, Flux Characteristics Recognition, Equivalent Circuit Parameters Differential Diagnosis, Difference Active Power Method. And according to various method to install differential protection.IPFC relays protection is another important part to CTPSS substation relays protections. The paper adopt many ways to set up over current protection, overvoltage protection, overheat protection for IPFC by Analysising IPFC and its isolation transformer's abnormality and fault states; then, to compensate generally IPFC under the situation that the devices are free from damage. At last, this paper proposes Wide Area Protection System (WAPS) .Wide Area protection method is to relay protect and auto control CTPSS' overall stability. It mainly installs Phasor Measurement Unit (PMU) which based on GPS Clock Synchronization Technology to collect and feedback measurement pots' Information in all the substations in the protection area. With measurement system, Dispatch Center can learn the real-time dynamic state circulate condition of whole system, and make relays protection motion, according to the Monitoring result to implementate wide area protection.