Study Of A Three-Phase Voltage Source Converter For A Multi-Functional Flexible Power Conditioner

Multi-functional Flexible Power Conditioner (FPC) makes use of an advanced synchronous condenser with a flywheel together with an AC excitation based on the vector control technology with power electronics device. The FPC incorporates the functions of the synchronous condenser and flywheel energy storage. It can perform multi-functions including energy storage, active and reactive power generation when used in power systems. This enables the proposed equipment to considerably enhance power system dynamic angular and voltage stabilities.Obviously, excellent excitation power supply is important for FPC to play satisfactory regulation performance, agility and reliability. This thesis is devoted to a development of Voltage Source Converter (VSC) for the FPC. The content of the thesis is as follows: At three phase stationary frame based model, a two phase stationary frame based model and a synchronously rotated frame based model for VSC are established at first. The state space averaging method is used to obtain the state average and the equivalent circuit. Based on the circuit obtained, the steady state operation characteristics are analyzed. A direct current control scheme is proposed in the thesis. This scheme combines the current state feedback decoupling and the dual close loop control. A dual close loop controller design technique which is fit for engineering application is developed. Digital realization of the proposed Space Vector Pulse Width Modulation (SVPWM) is given in the thesis.The design and the implementation of the VSC experimental setup is presented in details. The design of inductance and capacitance and the using of intelligent power module (IPM) are introduced in the thesis. The control card based on DSP chips is discussed. The work process of the VSC experimental setup is introduced.The influence of unbalanced three phase power supply on the VSC is discussed. The limit of the conventional method used to reduce the unbalance of the power supply is pointed out. The control technique under unbalance utility is indicated. By comparing two detecting methods for unbalanced voltage and unbalanced current, the thesis will adopt the filter method.