Research Of The Unified Controller For ATT

The rapid development of the world economy drives the increasement of user’s demand for electricity, the grid structure is increasingly complex and the operation task is also more and more heavy,for all of these reasons the power system is faced with lots of problems. According to the power grid’s characteristics, it’s very essential to take use of some control technologies such as the power compensation to improve the power flow and the operation parameters. Thus ensuring the power system operating safely and economically in various conditions.Most existing control strategies rely on the power electronic devices, however,the devices cost very much when applying to the high voltage and current system, it is very expensive in the large capacity system. ATT can improve the power flow economically and efficiently, but because of its limitations the regulation of ATT can not meet the requirement of flexibility, so it has a significant meaning to promote a new unified controller.This thesis studied the principle and structure of ATT, on this basis, we put forward three approaches for the connection between ATT and the unified controller, and choose one of them as the approach of the unified controller for ATT in this paper by comparing the advantages and disadvantages. This thesis analyzed the cooperation principle between ATT and the unified controller in detail, calculated the range of the output voltage of the unified controller when realizing any angle adjustment on the basis of ATT, analyzed the power characteristics of the unified controller under different operating conditions of ATT and compared the unified controller with other control devices in such aspects as principle,structure and function. As the core of the unified controller, this thesis analyzed and deducted the principle, mathematical model and control strategy of the three-phase voltage source inverter in detail, choosing the control mode of the inverter as bipolar PWM direct current control, and then verified the correctness of it by simulation in Matlab/Simulation. According to the study of the three-phase inverter, we determined the control strategy and parameters of the shunt part and the series part, set up the simulation model and simulating it in five aspects, by analyzing the simulation result, the modification of the unified controller is verified, thus verified the correctness of the design of the unified controller in this thesis.