A Method of Indirect Measurement of Filter Branch Current

Abstract

The present invention relates to an indirect measurement method of filter branch current, belonging to the technical field of the measurement of a filter. The Indirect measurement method comprises thesteps of (1) determining a topological structure and circuit parameters of a filter, (2) designing a digital filter according to the topological structure of the filter, wherein the digital filter represents a transfer function of branch current which needs to be measured and known current in the filter, and determining each part parameter of the digital filter according to the circuit parametersof the filter, and (3) calculating the branch current which needs to be measured according to the digital filter and the known current in the filter in the step (2). According to the indirect measurement method, the adding of a current measurement point in the branch which needs to be measured, the hardware modification of the filter is avoided, the cost is greatly reduced. The method has great flexibility and can be applied to filters with different structures, only the change of the type and parameters of the digital filter according to requirements is needed, and the measurement requirements of different filters and different branch current are satisfied.

Description

technical field [0001] The invention relates to an indirect measurement method of filter branch current, belonging to the technical field of filter measurement. Background technique [0002] In HVDC power transmission projects, AC filters are essential primary equipment. Its function is to provide reactive power compensation, maintain the AC bus voltage, and filter out the harmonic current generated by the AC system during the operation of the DC system. Whether it can operate stably and reliably is directly related to the stability and reliability of the entire high-voltage DC system. [0003] The AC filter is usually connected in parallel to the grid-side busbar of the converter transformer, which not only bears the high voltage of the system, but also flows a large amount of harmonic current, which is a severe test for the stability and insulation performance of the AC filter equipment. At present, most of the AC filters configured in high-voltage direct current transmis...

AI Technical Summary

Problems solved by technology

However, in engineering use, only some components and the main branch of the filter are equipped with current measuring points, which causes the corresponding current of some components and branches without measurement points to be missing, which cannot meet the configuration requirements of the protection system

Replacing the filter or adding a current measuring point in the branch circuit not only costs a lot and causes unnecessary waste, but also requires the transformation of the filter in operation, which has a wide range of influence and is difficult, and the overall benefit outweighs the gain

Images