Research On Distribution Terminal Unit Based On Autonomous Controllable CPU

The distribution terminal unit is an important part of the distribution automation.It mainly collects real-time operation information and sends it to the master station.At the same time,it accepts the master station’s instructions to control the equipment.Its security will directly affect the reliable operation of the entire distribution grid.The CPU chip is the core of the distribution terminal unit,but most of the currently used CPU chips have not been localized,and are vulnerable to technical blockades from abroad,thus being "stuck in the neck".In order to solve the self-controllability of distribution terminal units and realize the localization of core chips,it is of vital significance to ensure the safe operation of the power grid.The distribution terminal unit has the functions of collection,monitoring and control.In order to realize the self-controllable transformation of the distribution terminal unit,the selfcontrollable Allwinner T3 chip is selected for the hardware,and the completely open source Linux is used for the operating system.Based on the Allwinner chip,the CPU board is designed,and the parallel bus interconnection is used between the boards to ensure the transmission speed between the boards and the reliability of the protection device.In terms of software,a completely open source Linux is used,a driver program that is compatible with the board is developed,and all functions of the distribution terminal unit are fully realized.The developed distribution terminal unit has been tested comprehensively,and the test results show that the distribution terminal unit can operate reliably and accurately realize various functions.The frequency offset in the power equipment will cause deviations in the calculation results of the AC quantity.To solve the problem of frequency offset,frequency tracking and indefinite period sampling are used to deal with it.The device proposes a new idea,that is,using a fixed sampling period method,Lagrangian interpolation is performed on input signals at different frequencies to achieve fixed point sampling of each cycle,and then Fourier transform is used to calculate the harmonic components of each order.The influence of this interpolation method on the harmonic amplitude calculation results is theoretically analyzed,and the maximum error is deduced.The correctness of the theory is verified by the MATLAB simulation platform.The test results of the device also show the correctness of the theoretical analysis and the feasibility of the new method.