Research And Design On Hardware Of New Electronic Transformers Collector And Merging Unit

With the development of power industry and the increasing of transmission capacitanceand rated voltage in power system, especially in recent years with the rapid development ofthe digital substation and smart grid, conventional ferromagnetic transducers has been unableto satisfy with the digital and intelligent development needs of power grid. Electronictransformer is highlights and frontiers at home and abroad in electronic transformer research.The interface between the electronic transformers and bay device is the focus of thesuccessful application. As the key equipment of the digital output of the electronictransformer, the study of collector and merging unit will be of great significance.At first, this paper introduces the developent of electronic transformers, acquisitionsystem and merging unit in domestic and international mainly. The basic principle and systemstructure of electronic voltage transformer based on detecting current in capacitor and PCBplanar Rogowski coil current transducer are introduced. It discusses their advantages. In orderto make the two new electronic transformer in good application in practical engineering, thepaper data focuses on analyzing the new electronic transformer data acquisition system andmerging unit on the basis of the results of existing theory and practice. Then, it proposes amethod to acquisit signal based on STM32F103. The paper designs various modules inhardware, including pre-processing circuit module, ADC and MCU module, communicationmodule, post-processing circuit module, power module.Integrator is the key element in the two kinds of new type electronic transformers. So theintegration technique is described foucsly. In order to optimize integration performance, thetypical integral circuit is improved. The temperature characteristics of analog integrator areanalyzed, theory analysis and experiment data indicate that the temperature influents themeasurement accuracy. Digital integrator allowing for better accuracy and higher stability aremore adequate than analog one. In order to further improve the measurement accuracy, Digitalintegral algorithm is studied and the response of steady and transient current based ontrapezoidal integral algorithm is analyzed and simulated, techniques to deal with the drift andinitialization in digital integrator are proposed. The laboratory simulation testing platform isestablished and tested basing on new PCB planar Rogowski coil current transducer. Testingresults prove the validity of the design method.The definition of the merging unit is introduced, the features of the merging unit isanalyzed. According to the merging unit of data restoring module, data processing module anddata outputing module, it proposes a new method using FPGA and DSP for implementing the merging unit．The merging unit’s various modules are designed in hardware, which includingFPGA systems, DSP systems, ethernet module.