Active Filter
AssigneeMitsubishi Electric Corporation
InventorKempei Seki
Life of this patent
Estimating the term…
Abstract
An active filter that can remove harmonic noises other than the fundamental wave in a system having many unspecified harmonics and can contribute to the stable operation of the system, and improvement in the quality of power is provided. Using the following power equation (1) for a single-phase circuit as a basic expression, an active power effective value P and a reactive power effective value Q are obtained by integration operation with an active power instantaneous value and a reactive power instantaneous value, an instantaneous voltage estimation value is calculated, the system side fundamental wave current is obtained based on these values, and then the system side fundamental wave current is subtracted from the load current to obtain compensation current as the output of the active filter.
Claims7
An active filter connected between a power system and a load to supply compensation current used to restrain a harmonic component in load current, comprising:
- voltage current detecting means for detecting instantaneous voltage and instantaneous current at the power system;
- A/D converting means for converting the detected instantaneous voltage and the detected instantaneous current into digital data;
- active power instantaneous value and reactive power instantaneous value calculating means for calculating an active power instantaneous value and a reactive power instantaneous value using the instantaneous voltage and the instantaneous current converted to the digital data;
- active power effective value and reactive power effective value calculating means for calculating an active power effective value and a reactive power effective value using the calculated active power instantaneous value and the calculated reactive power instantaneous value by integration method;
- system side fundamental wave current calculating means for calculating fundamental wave current on the power system side using the calculated active power effective value and the calculated reactive power effective value;
- and
- compensation current output means for outputting the difference between the load current and the system side fundamental wave current as the compensation current.
Dependencies are inferred from the claim text.