The Research On Operating And Control Characteristic Of DC Transmission System Based On Novel Converter Transformer

With the rapid development of our country's electric network, DC transmission system plays an important role in nationwide transmission network. Converter transformer is a very important technical equipment. The auto-compensator and harmonics shade converter transformer construct a novel inductive filter scheme with its special winding up and connection way. The filter scheme has a simple construction without complex control segment, but filtering effect is very good, so it has a good application prospect.The novel DC transmission system this thesis study on adopt the auto-compensator and harmonics shade converter transformer. Firstly this paper expounds the new-type converter transformer's design feature and the new-type filtering way that uses the coupling winding's harmonic ampere-winding balance as the filtering mechanism briefly, then the basic theory of the DC transmission converter has been analyzed and characteristic equations of converter have been given when it works as a converter or a inverter respectively, based on this, it establish the mathematic model of DC transmission based on the novel converter transformer and derive the dynamic equations of the novel DC transmission system, and it also proposes the control methods and their characteristic of DC transmission system. Afterward, the simulation model of the novel DC transmission system has been established in MATLAB, the simulation analysis verified the model's correctness and the superiority in the field of harmonic suppression and improving the system's steady-state operation performance. At last, three PID controller based on the novel DC transmission system have been designed--- PID Controller Fixed Arguments(FAPID), PID Controller with Variable Arguments (VAPID) and Fuzzy PID Controller with Variable Arguments(FUZZY- VAPID). Simulation study of them have been made on the novel DC transmission system, we can gain the waves of voltage and circle of the system, the results shows that VAPID controller and FUZZY- VAPID controller both can reach a satisfactory effect compared with FAPID controller.