Adaptive system for controlling noise generated by or emanating from a primary noise source

An adaptive system for controlling noise generated by or emanating from a primary noise source, comprising:

• (a) reference means for generating a reference signal that is correlated with the noise emanating from the primary noise source;
• (b) secondary source means for generating a plurality of secondary sound waves;
• (c) detection means for detecting a plurality of far-field sound waves in a far-field of said primary noise source, and generating a plurality of error signals each of which is indicative of the power of a corresponding far-field sound wave;
• and
• (d) adaptive control means for controlling said secondary source means in accordance with said reference signal and said error signals so as to minimize the power in said far-field sound waves;
• wherein said reference means comprises means for detecting acoustic noise in a near-field of said primary noise source;
• wherein said secondary source means comprises a plurality of loudspeakers;
• wherein said detection means comprises a plurality of microphones;
• and
• wherein said adaptive control means comprises:
• (i) correlation means for generating autocorrelation data on the basis of said reference signal and generating crosscorrelation data on the basis of said reference signal and said error signals;
• (ii) fast Fourier transform (FFT) means for generating auto-spectrum data and cross-spectrum data on the basis of said autocorrelation and crosscorrelation data;
• (iii) finite impulse response (FIR) means, coupled to said reference means, for filtering said reference signal in accordance with a plurality of weighting functions and for providing filtered versions of said reference signal to control the output of said secondary source means, each of the weighting functions being associated with a corresponding one of said secondary sound waves to be generated by said secondary source means;
• and
• (iv) adapting means for processing said auto-spectrum cross-spectrum data so as to derive said weighting functions, and for providing said weighting functions to said FIR means.

A power generation system, comprising a combustion turbine coupled to an exhaust stack, and an adaptive, active control system for controlling multi-mode acoustic noise generated by said combustion turbine and emanating from said exhaust stack, said active control system comprising:

• (a) reference means for generating a reference signal that is correlated with the noise generated by said combustion turbine;
• (b) secondary source means for generating a plurality of secondary sound waves;
• (c) detection means for detecting a plurality of far-field sound waves in a far-field of said exhaust stack, and generating a plurality of error signals each of which is indicative of the power of a corresponding far-field sound wave;
• and
• (d) adaptive control means for controlling said secondary source means in accordance with said reference signal and said error signals so as to minimize the power in said far-field sound waves, said adaptive control means comprising:
• (i) correlation means for generating autocorrelation data on the basis of said reference signal and generating crosscorrelation data on the basis of said reference signal and said error signals;
• (ii) Fast Fourier Transform (FFT) means for generating auto-spectrum data and cross-spectrum data on the basis of said autocorrelation and crosscorrelation data;
• (iii) finite impulse response (FIR) means, coupled to said reference means, for filtering said reference signal in accordance with a plurality of weighting functions and for providing filtered versions of said reference signal to control the output of said secondary source means, each of the weighting functions being associated with a corresponding one of said secondary sound waves to be generated by said secondary source means;
• and
• (iv) adapting means for processing said auto-spectrum and cross-spectrum data so as to derive said weighting functions, and for providing said weighting functions to said FIR means.

A method for controlling noise emanating from a primary noise source, comprising the steps of:

• (a) generating a reference signal that is correlated with the noise emanating from said primary noise source;
• (b) generating a plurality of secondary sound waves in a near-field of said primary noise source;
• (c) detecting a plurality of far-field sound waves in a far-field of said primary noise source, and generating a plurality of error signals each of which is indicative of the power of a corresponding far-field sound wave;
• and
• (d) controlling the generation of said secondary sound waves in accordance with said reference signal and said error signals so as to minimize the power in said far-field sound waves, said controlling step including the following sub-steps:
• (i) generating autocorrelation data on the basis of said reference signal and generating crosscorrelation data on the basis of said reference signal and said error signals;
• (ii) generating auto-spectrum data and cross-spectrum data on the basis of said autocorrelation and crosscorrelation data;
• (iii) processing said auto-spectrum and cross-spectrum data so as to derive a plurality of weighting functions;
• and
• (iv) filtering said reference signal in accordance with said weighting functions, and employing filtered versions of said reference signal to control the generation of said secondary sound waves, each of the weighting functions being associated with a corresponding one of said secondary sound waves to be generated.