New transformation for efficient DSP control of active power-line conditioners

This paper presents a new transformation scheme for the control of an active power-line conditioner, a power electronic device which is designed to suppress the power-line distortions caused by the nonlinear loads. Currently, the method of instantaneous power transformation is the most popular one for the active power-line conditioning control. This method uses the measurements of the power-line voltage and current to estimate the required harmonic compensation. The method requires much hardware for the measurements and many computations. The high accuracy hardware for measurements are costly and many computations can introduce truncation errors. Also, this method is sensitive to the power-line voltage measurements and may introduce control errors. A new simple transformation method is developed to overcome these difficulties. This control computes the correct harmonic compensation using the power-line current measurement only. This requires less hardware for the power-line voltages measurements and simplifies the computational processes. Unlike the traditional method, the accuracy of the new control method is not affected by the line voltage measurements, therefore, it is reliable under any power-line condition. An active power-line conditioner has been successfully developed to validate the accuracy and efficiency of the new control method. Typical test results are given in the paper.