Research Onalgorithm Of Electromechanical Transient Simulation And Control For Electric Power System Including Generator And HVDC

With the countrywide interconnection of wide-area power systems, the fundamental framework of Chinese national power grid has developed into a large scale AC/DC hybrid power system, as a result the operation and control become more and more complicated. To meet increasing demands of HVDC power transmission being put into operation and offer accurate analytical tools to operation, design and planning departments, it's necessary to set up a transient simulation model which can accurate simulate the characteristics of HVDC power transmission and research transient stability simulation algorithm to achieve it. Weak ties of regional power grid and widely application of high magnification excitation system weaken the system damping, and the characteristics of dynamic stability become more and more complicated. Currently, Power System Stabilizers (PSS) and DC-modulation controller are widely used to improve the system damp and suppress the system oscillation after a large disturbance.This paper studies the PSS models, and introduces the method of obtaining the difference equation. In addition, the main contribution of this dissertation is how to realize those models in transient stability analysis. At last, the realization of PSS model is studied in the IEEE 4-machine 11-bus test system, and the results of simulation can well approximate to that of BPA. The validity of the proposed approach is verified.This paper studies the fundamental principals, control characteristics and simulation models of two terminal HVDC power transmission systems, and develop a HVDC electromechanical simulation model which can consider the complex control model of HVDC, such as HVDC regular, VDCOL, modulation controller, commutation failure simulation, bipolar block and auto-restart function. According to the physical relationship between AC system and DC system, the interface equation is developed, and Bidirectional Module Reduction (BMR) is used to electromechanical transient simulation of AC/DC hybrid power system. The substance of the BPR technique is simultaneous solution method based on implicit trapezoidal integration method and Newton method. The BPR technique will become more modular, expandable and easier for programming, as well as remaining quick convergence with high precision and good numerical stability. The simulation algorithm is realized by C++ programming. The validity of the proposed approach is verified by the simulation results of 2007 southern power grid.A method for parameter-optimization of DC-modulation controller has been proposed. In this method, the parameters tuning problem of the DC-modulation controller is converted to the non-linear optimization problem with parameters constraints, and then the constrained optimization problem has been converted to the unconstrained optimization problem. The gradient of the objective function is obtained by means of the simulation of trajectory and trajectory sensitivity. And then the parameters of the DC-modulation controller are optimized by Quasi-Newton Algorithm (DFP). Because the objective function reflects the power oscillation behavior of AC/DC interconnected power systems, the proposed method can be used to effectively damp the power oscillations of the AC/DC system incurred by severe disturbances. The eigenvalue analysis and time-domain simulations on the IEEE 4-generator AC/DC system verify the effectiveness and the robustness of the proposed method.