Analysis and Improvement of a DC Filter Overload Protection Action
The DC filter overload protection is an important way to protect the hollow core reactor and resistor of the DC filter from excessive thermal stress,which may cause insulation damage or even burn out of the components.In this paper,the algorithm principle of DC filter overload protection in the actual project is analyzed in detail,focusing on the skin effect filter that reflects the skin effect of the air-core reactor and the design principle of the skin effect filter which causes the change of harmonic resistance due to proximity effect and the shunt coefficient filter which needs to be configured due to the lack of measuring points of the electromagnetic current transformer.Aiming at an example of the malfunction of the overload protection of the DC filter in the actual project,a current transformer con-figuration scheme that can avoid the malfunction of the overload protection of the DC filter is proposed,and the rela-tionship between the effective value of resistor branch current and the protection setting value is directly compared as the criterion of overload protection.Based on actual transient fault waveforms and combined simulation analysis using the single-step block method,the simulation results show that compared with the traditional implicit trapezoidal nu-merical integration method,the single-step block method can effectively suppress numerical oscillations.The new pro-tection scheme can avoid the impact of internal grounding faults of the DC filter on the overload protection of resistors and has practical engineering application value.
DC filterOverload protectionProximity effectFault simulation
万方数据
维普
