ADALINE-based controller for active power-line conditioners

Active power-line filters based on the injection method, depend on the distorted line current signal and the voltage signal at the point of injection. These signals are used by the control circuit to make the converter inject the proper compensating current and regulate the DC-side current or voltage of the converter. In this paper, a new adaptive linear neuron (ADALINE)-based control scheme for a modular single-phase active power-line conditioner is proposed. Two ADALlNEs are used to process the signals obtained from the line. The first ADALINE (current ADALINE) estimates the discrete Fourier coefficients of the distorted line current signal which will be used to construct the modulating signals of a number of current-source inverter (CSI) modules, each dedicated to eliminate a specific harmonic. The second ADALINE (voltage ADALINE) estimates the fundamental component of the line voltage signal to be used as the synchronizing signal for the regulation of the I/sub dc/ of the CSI modules. This information can also be used in the compensation of the voltage sags and swells in a more advanced phase of the project. Both ADALINEs have the ability to track the variations in the system frequency. Power losses are reduced by adjusting the I/sub dc/ in each CSI module according to the magnitude of the corresponding harmonic current. Fast response and accuracy of the ADALINE combined with fast response and low DC energy storage requirement of CSI topology, makes the above scheme a suitable on-line technique for high power applications. The theoretical expectations are verified by digital simulation using EMTDC.