Ac/dc Electromagnetic Transient Simulation Of Power System

with the state policy "nationwide interconnection, sending power from west to east, mutual supply between south and north"implemented rapidly, HVDC (High Voltage Director Current) technique is extensively developed and applied. In the HVDC power system, there are many power electronic devices. Because the operation characteristics of different kinds of power electronic devices are different, it's a challenge for power system electromagnetic transient simulation to factually reflect the characteristics of power electronic devices. Thus, deep studies of program structure, element model, system regulation, control and simulation algorithm are necessary for digital simulation to capture the operation law of the power electronic devices during power system electromagnetic transient process. Thus, electromagnetic transient simulation of AC/DC hybrid power system is deeply studied and some achievements are gained. The main content of this thesis is presented as follows:Based on the fourth-order R-K-T method, the synthetic companion model of inductance is derived to promote the accuracy and numerical stability of the electromagnetic transient simulation program.1. Based on the variable resistance model of switch, the integrated switch model is proposed. The model can decrease the calculation quantities through the reduction of the numbers of independent elements in system. This model is applicable to the switch operation of lumped parameter elements, such as inductance, resistance and capacitance and the switch operation of line model described with distribution parameters and wave theory.2. Based on the theory of PLL (Phase-Lock Loop), a method of real-time phase calculation is proposed. According to the formulationθ=θ+wΔt , this method use the zero-crossing point and system frequency acquired by PLL to gains real-time phase. The example shows that the method is able to obtain higher precision phase angle compared with that obtained by PLL. .3. CDA (Critical Damping Adjustment) technique is deeply studied, and the relationships between the back Euler and the system status, system parameter, and the step of system simulation are derived. And then, a new strategy solving the synchronous switch problem is proposed.4. Based on the above four aspects, a simulation system, including generators, transformers, lines, filters and converter components is developed by the object-oriented programming technology. The system develop could simulate practical AC/DC system.Many examples prove the correctness and actual feasibility of the above-mentioned works.