Three-phase Voltage Synthesis 360° Direct Power Controller

In order to improve the power flow control capability of the power grid,enhance the power transmission efficiency of the power grid,and to address the problem of system equipment failure caused by the deployment of large-capacity DC energy storage components in the existing mainstream flexible AC transmission system,this thesis proposes and researches a three-phase voltage synthesis 360° direct power controller.The proposed controller is capable to control the power flow both reactive and active independently in grid power transmission by providing an adjustable compensation voltage with a 360° regulation range to the power grid.Firstly,based on the concept of direct power flow controller(DPFC),the circuit topology of a three-phase voltage synthesis 360° direct power flow controller is derived according to the principle of voltage vector synthesis.Buck-type AC converter with a simple structure and a high energy transmission efficiency is used as the modulation unit of the compensation voltage.Then this thesis analyzes and derives the input-output relationship of the circuit in the case of balanced grid,and makes a detailed analysis of the compensation voltage regulation area.At the same time,the adjustment characteristics of the regulated grid voltage within the 360° regulation range of the compensation voltage are further analyzed.In the case of unbalanced power grid,this thesis also states theoretically that three-phase voltage synthesis 360° direct power flow controller has the ability to adjust the unbalanced power grid.Finally,a prototype for three-phase voltage synthesis 360°direct power flow controller is developed.The hardware design and the relevant software design of the whole system are introduced.In the case of balanced power grid,experimental waveforms of the prototype are measured by the experimental platform built by DSP controller,and the experimental waveforms in the case of unbalanced power grid are given by Saber.The feasibility of the three-phase voltage synthesis 360° direct power controller and the correctness of its theoretical analysis are confirmed by the experimental results and simulation analysis.