Embedded Controller Research And Design Of Electronic Transformer Dynamic Feature Testing Terminals

Transformers transform voltage and current signals on transmission lines of sub-stations and deliver them to sub-stations’ secondary devices to let them carry out their primary operations like measurement, protection, status monitoring, etc. Electronic transformers are future devices gradually replacing former traditional electro-magnetic transformers. The most significant feature of electronic transformers is the digital signal outputs when their principal functional performances increase a lot. This feature is the basis and prerequisite to achieve networking of secondary devices, and automatization of substations.Currently, electronic transformer devices are on the phase of testing running in our country. It holds back the application and extension process of electronic transformer devices because the testing methods are mainly aiming to the sensor module, and they are way too simple to test and estimate the dynamic response of the whole electronic transformer devices. Against this background, the Electricity Power Science Research Institute engaged in collaboration with Power System Wide Area Measurement and Control Lab in School of Energy Science and Engineering(SESE) of University of Electronic Science and Technology of China(UESTC) to research the dynamic response of electronic transformer devices testing method and the related testing device development.The dynamic response feature of electronic transformer devices testing method is to test the response of ECT/EVTs’ acquisition system with complicated electromagnetic instant simulation signal inputs, and then estimate their performance accordingly. The developed electronic transformer dynamic response feature testing device consists of an upper computer platform, a high voltage operation amplifier and an embedded control terminal. It outputs the simulation signals of a set of 3-phase voltage and current sensor signals to the testing objects, electronic voltage transformers(EVT) and electronic current transformers(ECT). The upper computer platform acquires the response outputs electronic transformers from merge units(MU) and then does the analysis accordingly.ARM is a CPU core architecture based on RISC. Control devices with ARM cores are with the features like powerful function, low cost, low power consumption, structural flexibility, etc. They are widely used in many fields including embedded control. ARM based embedded controller carrying Linux operation system is great dealing with network communication tasks. FPGA is a kind of digital logic devices with parallel structure. FPGAs are able to accomplish completed tasks like algorithm bottom layer acceleration, parallel hardware control, multi-protocols process, etc. With the development of IC technology, FPGAs are increasingly applied in system-level embedded control.The embedded control terminal of electronic transformer dynamic response feature testing device has 6 customized system boards based on FPGA+ARM architecture. Concerning the instant electromagnetic signal feature applied in testing, this article tells the functional design of embedded control terminal in detail after deep study in specification and design method of the FPGA logic controller and ARM processor. It contains the design of inner and outer hardware block interfaces, the design of data stream buffer, the design of master/slave mode within 6 terminals and their synchronization method. And then it introduces how the embedded control terminals cooperate with the upper computer platform with data stream and control commands to manipulate and synchronize simulation data stream outputs, how they perform three different kinds of tests accordingly, and how the embedded terminals offer the aid to the analysis of upper computer platform.In the end of this article, it draws the future of the electronic transformer dynamic response feature testing, and lists suggestions to improve the current testing device.