K. Çağatay Bayindir

Hierarchical neuro-fuzzy current control for a shunt active power filter

This paper presents the design of a hierarchical neuro-fuzzy current control scheme for a shunt active power filter compared with a single fuzzy controller scheme. A single fuzzy controller scheme is presented first and an ANFIS based neuro-fuzzy controller is connected hierarchically to the first one to improve the performance. Simulation results show that harmonic compensation is achieved with both schemes, however switching performance is superior for hierarchical scheme. The method of switching controller development in this paper is new and can be applied to other power electronic converter applications for improved performance.

Implementation of a Non-Linear Adaptive Filter Based Sag Detection Method for Dynamic Voltage Restorers under Unbalanced Fault Conditions

The most common power quality problems in distribution systems are related to unbalanced voltage sags. Voltage sags must be detected quickly and corrected in a minimum amount of time. One of the most widely used methods for sag detection is based on the d-q transformation. This method has the disadvantage of missing the detection of unbalanced faults, because this method uses a voltage sag level signal obtained from the average of 3 phases for sag detection. In this paper, an adaptive filter sag detection method is proposed for Dynamic Voltage Restorers (DVR) under unbalanced fault conditions. The proposed DVR controller is able to detect balanced, unbalanced and single phase voltage sags. A novel reference voltage generation method is also presented. To validate the proposed control methods, a 3-phase DSP controlling a DVR prototype with a power rating of 1.5-kVA has been developed. Finally, experimental results are presented to verify the performance of the proposed control methods.

Analysis and comparison of passive damping methods for shunt active power filter with output LCL filter

Recently, LCL filter which is commonly preferred in grid connected inverters has found its common usage in shunt active power filters. LCL filter can suppress the switching harmonic ripples effectively. However, it has resonance problem which results unstable system. The resonance problem can be solved with damping the resonance using passive damping methods. The design of LCL filter with using PD is a challenging issue because APF generates currents in a wide harmonic spectrum range to compensate harmonics. The aim of this paper is to present the design procedure of LCL filters with different passive damping methods for SAPF and analyze them in terms of damping performances and power losses. The performance and analysis of LCL filters designed for SAPF is performed with simulation model developed in MATLAB/Simulink.

Experimental architecture of a DSP based signal generation for PWM inverter

This article presents the analysis and design of an experimental study on the implementation of digital signal processor (DSP) controlled single‐phase pulse width modulation (PWM) inverter based on Simulink and Real Time Workshop in Matlab. Each stage of PWM signal generation using DSP is comprehensively presented to ease the design and analysis of complicated control algorithms in DSP based solutions. The article also enhances knowledge more about experimental studies in the laboratory. The performance of the DSP based PWM inverter design is analyzed through simulation studies under various switching frequencies and the theoretical considerations are successfully validated with experimental prototype based on TMS320F2812 DSP.

Extraction of voltage harmonics using multi-layer perceptron neural network

This paper presents a harmonic extraction algorithm using artificial neural networks for Dynamic Voltage Restorers (DVRs). The suggested algorithm employs a feed forward Multi Layer Perceptron (MLP) Neural Network with error back propagation learning to effectively track and extract the 3rd and 5th voltage harmonics. For this purpose, two different MLP neural network structures are constructed and their performances compared. The effects of hidden layer, supervisors and learning rate are also presented. The proposed MLP Neural Network algorithm is trained and tested in MATLAB program environment. The results show that MLP neural network enable to extract each harmonic effectively.

EPLL based controller for voltage harmonic mitigation in grid connected wind systems

Voltage harmonics are very important voltage disturbances which induce overheating of transformer/generator, connection loss and rise of current rating in grid connected wind energy systems. In this paper, Enhanced Phase Locked Loop (EPLL) based controller method is proposed to generate reference signals of voltage harmonics at grid-side voltages. In order to achieve the harmonic compensation, EPLL based controller method is tested to compensate voltage harmonics for balanced and unbalanced conditions in Dynamic Voltage Restorer (DVR) tied grid-connected wind energy systems. The performance results of EPLL based controller demonstrate that it is a very effective technique for harmonic compensation under steady-state and transient conditions.

Survey of inverter topologies implemented in dynamic voltage restorers

Voltage disturbances which affect the stability of electrical networks are the most important power quality problems. The most known voltage disturbances are voltage sag and swell in distribution systems. Dynamic Voltage Restorer (DVR) is the most effective device to compensate these voltage disturbances among the custom power devices. The basic structure of a conventional DVR consists of an inverter, dc link capacitor, injection transformer and filter. The major component in DVR is inverter that generates controlled voltage to compensate voltage sag/swell and other problems such as flicker, interruption and harmonics. Each inverter implemented in DVR has individual properties such as voltage level, unbalanced compensation capability and/or dc link capacitor requirement. This paper aims a comprehensive review on different inverter topologies according to the number of phases, size, voltage level and structure of DVR. In addition, individual properties of inverters are presented in this study.

Interline hybrid unified power quality conditioner

This paper proposes a new interline hybrid unified power quality conditioner (IHUPQC) structure to improve the power quality of distribution feeders and to decrease the power ratings/voltages and switching losses of voltage source converters (VSCs). The IHUPQC consists of dynamic voltage restorer (DVR), an isolated dc-dc converter and a shunt hybrid active power filter (SHAPF) with a common dc bus. The inverse park phase locked loop (IP-PLL) technique is used to detect the distortions of signals in both feeders. Sinusoidal pulse width modulation (SPWM) based voltage control and current control are used for DVR and SHAPF respectively. The isolated dc-dc converter has PI controller based simple phase shift (SPS) technique. The proposed structure is designed for 34.5 kV voltage level and simulated by using PSCAD/EMTDC to verify system.

A novel low cost sag/swell generator

This study presents a new Sag Swell Generator (SSG) topology to generate several power quality problems such as sag, swell and interruption. In this paper, bridge type bidirectional switch based SSG is presented to generate different fault conditions. The main contribution of proposed topology is to provide low-cost and simple solution compared to conventional transformer based SSG topologies. The experimental results show that the proposed SSG is a novel topology for low-cost laboratory applications.

Performance investigation of shunt hybrid active power filter with a synchronous reference frame based controller

This paper presents a novel synchronous reference frame based (SRF) control strategy for shunt hybrid active power filter (SHAPF). The control strategy includes a direct current control (DCC) and an indirect current control (ICC) strategy. SHAPF can achieve harmonic compensation and dynamic reactive power compensation with the proposed controller. In this proposed method, as distinct from studies in literature, dynamic reactive power compensation and dc link voltage control is realized with ICC and harmonic current compensation is realized with DCC. Also, the proposed controller provides a variable SHAPF dc link voltage which is adjusted according to the reactive power compensation requirements in order to decrease the switching losses of converter and achieve power savings. The performance of proposed controller is verified with experimental results.