Neuro-Fuzzy Controller and Bias Voltage Generator Aided UPQC for Power Quality Maintenance

Abstract

  Abstract—Power quality (PQ) of power operating device is one of today's most discussed topic but also it is a most problematic subject in recent years. The increasing application of power operating device can cause PQ disturbances. Avoiding the PQ disturbance and enhancing the PQ are the difficult tasks. More power electronics devices are used to overcome the PQ disturbances. Unified power quality conditioner (UPQC) is one of the power electronics devices that are used for enhancing the PQ. It consists of two voltage source inverters (VSIs) and sharing with one DC link capacitor. The discharging time of DC link capacitor is very high, and so it is the main problem in UPQC device. To eliminate this problem, an enhanced Neuro-fuzzy controller (NFC) based UPQC is proposed in this paper. The DC link capacitor discharging time is eliminated by installing a bias voltage generator. The input of bias voltage generator is generated by using a NFC. NFC is the combination of neural network (NN) based controller and fuzzy logic controller (FLC). Initially, the error voltage and change of error voltage of a nonlinear load is determined. Then the voltage variation is applied separately to FLC and NN-based controller. The output voltage of FLC and NN-based controller is calculated, and then the mean voltages of the two methods are applied to the bias voltage generator and finally, the PQ of the system is enhanced. The proposed controller is tested and the results of tested system and their performances are evaluated.