The Three-pulse Model Application In High Voltage DC Filter Design

The converters of the HVDC system yield harmonic voltages and currents because of its non-linearity. When the harmonic currents inject the AC and DC systems connected to the converters, they will do harm to the systems. The influence of the harmonics on DC side is mainly the disturbance on telecom lines. In order to decrease this disturbance, it is necessary to add DC filters when the DC transmission lines are built on stilt. The standard of DC filter design is to make sure of the minimized DC filters cost under the acceptable harmonic level.The correlative items of DC filters are researched on the basis of Gezhouba-Shanghai HVDC transmission project. In the analysis the three-pulse model is used to simulate converter, which takes into account the impact of the stray capacitance. The harmonics distribution on DC lines is simulated accurately, especially the harmonic ignored in old models. The application of three-pulse provides the more accuracy data and evidence. The correlative calculation is on the basis of XLNT program of ABB.