Research On Power Flow Algorithm With Considering VSC-HVDC

Since the world’s first HVDC project put into commercial operation, the developmentof HVDC system has experienced great changes. In recent years, photovoltaic and windpower have received more and more attention because of their advantages of cleanlinessand renewable. But it has created new problems when they connect with AC systems orconventional HVDC networks. When the new energy connects to the grid, power flowequations will be changed comparing to the traditional ones. Therefore, solving theproblem of power flow calculation with considering VSC-HVDC and new energyresources has great significance for the future construction of the grid.Firstly, the constitution and operating principle of VSC-HVDC are studied in thispaper. And then, the effects of each part of VSC-HVDC are analyzed.On this basis,VSC-MTDC system and its mathematical model are studied, the steady-state control ofVSC is presented.This paper uses a unified iterative algorithm power flow calculation forAC/DC hybrid systems.DC system equations, power deviation equations and the form ofthe Jacobi matrix are also introduced in details. Based on the different control modes ofVSC, the Jacobi matrix is modified.At the same time of the introduction of the unifiediterative method, this paper also gives the flow chart of a sequential algorithm.Using thedescribed unified iterative method, the examples of VSC-MTDC system, regionalinterconnected system and the complex compound system are calculated and certificated,the calculation results show that the effectiveness and accuracy of the unified iterativealgorithm and the adaptability for different examples.On this basis, the power flow algorithm with considering new energy power isresearched. The operation principles of PV and wind power are also respectively discussed.The established mathematical models are combined with the power flow model, the powerflow of power systems containing PV and wind power is calculated using the unifiediterative method.