Voltage Stability Analysis Of AC/DC Combined System

With the development of national economy, demand of power in various industries has increased sharply. As a result of its technical and economical advantages, HVDC technology has been playing an important role in the development of power industry such as long distance great capacity transmission. Although AC/DC combined transmission system has been the inevitable trend, it has also brought a series of new problems. The phenomenon of voltage instability on the converter bus is an important problem affecting normal running of HVDC, especially HVDC system connected to weak AC system. This is a challenge for feasibility and control of HVDC, so it is necessary to study mathematical model and arithmetic for voltage stability assessment on converter bus of AC/DC power system.In order to find proper method to evaluate voltage stability of AC/DC system, this paper sums up and evaluates methods of static voltage stability analysis for AC/DC system firstly. The diversity of HVDC control fashion and running fashion results in complexity of assessment method of converter bus voltage stability. Until now, there is no systemic analytical method. Most methods adopted are extended from traditional methods for AC system. The difficulty for extension is uninterrupted consideration of overflow of HVDC system variables and adjustment of HVDC control fashion with the increase of load and the decline of convert bus voltage.As the nonlinear programming model of analysis of voltage stability for AC system has been proposed, this paper consolidates AC pattern and DC pattern and...