Research On The Static Voltage Stability Of AC/DC Hybrid Transmission System

With China’s implementation of power development strategy, HVDC technology has its uniqueadvantages on the technical and economic, it is applied more and more in high voltage power grid ofchina. AC-DC systems bring a range of new issues in the operation and safety of the power grid, thestability of AC-DC systems is one of the key problems. Research on the stability of AC-DC systemsprovide strong reference and technical support of the power grid, and have important theoreticalsignificance and practical value.First, this paper gives comprehensive review and summary of the stability problems of AC-DChybrid transmission system, and gives the steady-state model and power equation of the hybrid HVDCsystem. On this basis, based on the sensitivity analysis, studies the static stability of the hybrid HVDCsystem voltage; based on the principle of decoupling calculation, gives derivation of the AC-DC hybridtransmission system voltage stability index formulas and calculation steps. Using the method above,analysis the voltage static stability of Huliao hybrid HVDC system, and calculate the hybrid HVDCsystem voltage static stability sensitivity index under different transmission, failure and different DCcontrol mode. Combine with the sensitivity index above, this paper studies the operation control ofHuliao hybrid HVDC system.In order to strike the current running point margin of system, this paper gives further study of thecontinuous power flow calculation method of hybrid HVDC system. First this paper analyses theapproach of Continuous Flow Algorithm in DC transmission system, realizes the prediction andcorrection calculation of AC-DC hybrid system by the decoupling and passing of AC-DC couplingvariables; gives continuous power flow control mode and implementation method of the transformer inthe converter station and shunt capacitor, and gives the calculation process.In this paper, the example system is used to analyze calculate, and obtains voltage stability marginunder a variety of typical DC operation mode to verify correctness and validity of continuous powerflow Algorithm; finally, this paper analyses and calculates practical engineering examples.