Research Of Merging Unit Based On FPGA And PowerPC

With the development of higher voltage and larger capacity of power system, a higher requirement for the reliability and the stability of the grid is put forward by the social economy. Because of the large-scale application of all kinds of new energy power generations, reliable grid connection and intelligent dispatching become the problems needed to be solved. Smart grid with a variety of advanced technology is recognized as the best solution to the above problems. As the measuring equipment in the digital substation, electronic instrument transformers overcome the defect of electromagnetic instrument transformers such as low dynamic range, narrow band and ferroresonance. The electronic instrument transformers have digital output that the conventional electromagnetic instrument transformers do not have, which plays an important part in data sharing in the digital substation and in large scale power grid. Consequently, it's the basis of the advanced decision support system in the smart grid.This paper illustrates a merging unit based on FPGA and PowerPC technology. It's characterized by dual-processor FPGA and PowerPC hardware system as the core, which can make full use of the FPGA's high-speed multi-channel parallel processing and the high stability of the PowerPC and its rich peripheral interfaces. Owing to the air core coil is widely used in power system, a digital integrator with feedback loop is designed. The offsets of DC and disturbance signals can be restrained by the feedback loop. A digital interpolation is designed to realize synchronization in order to achieve the strict synchronization requirements of merging unit. A digital phase-shifting algorithm is designed to adjust the phase differential. A control system based on VxWorks is designed to realize the High stability control.As the digital output module of the combined electromagnetic instrument transformers which are used in 110kV and 220kV power system, the designed merging unit passed the type test in the Electrical Equipment of Power Industry and Testing Center. The test results show that the designed combined electromagnetic instrument transformers meet the accuracy requirements of the 0.2s level in IEC60044-7/8, and the designed merging unit passed the EMC Test.