Study On Algorithms Related To Voltage Security On-line Assessment, Index, And System Building

Voltage stability is the question which has aroused general concern in electric power industry. The accurate real-time assessment of voltage stability of power grid has important significance. The system of voltage security on-line assessment is drawing a universal attention in modern electric power workers.The methodology of voltage stability assessment is the basic work for the system of voltage security on-line assessment. Continuation power flow (CPF) is a powerful analytical method in static voltage stability analysis. Based on the former generator reactive power limit treatment, a new method of reactive power dispatch under the excitation current limit was given out. It can reschedule the generator's output during the process of the CPF according the MW and voltage of each generator, which can make better use of the reserved power in power grid. The simulation results of the IEEE 30 system show that the proposed model is effective and rational.A good voltage stability index is the key to voltage stability monitoring. By theoretical derivation, a voltage stability index based on CPF (Vsic) is proposed in the dissertation. Vsic index is intended to use the rate of Lvsi index changes to describe the system voltage stability level, the branch which easy to voltage instability means the rate of Lvsi index change greatly. Combination of PMU/WAMS technology, the index can be applied to large-scale power grid monitoring of static voltage stability.Based on the comprehensive research on VSA (Voltage Stability Assessment) systems and result in this dissertation, an on-line voltage security assessment system framework adapt to present power system development is given out. According to the framework of the proposed system, the function of each module, workflow, and system characteristics are defined. On the basis present research, directions to be deepening are pointed out.