Generalized UPQC system with an improved Control Method under Distorted and Unbalanced Load Conditions.

Abstract-

Power quality has become an important factor in power systems, for consumer and household appliances with proliferation of various electric and electronic equipment and computer systems. The main causes of a poor power quality are harmonic currents, poor power factor, supply-voltage variations, etc. A technique of achieving both active current distortion compensation, power factor correction and also mitigating the supply-voltage variation at the load side, is compensated by unique device of UPQC presented in this paper and this paper presents a modified synchronous-reference frame (SRF)-based control method to Shunt active filter and instantaneous PQ (IPQ) theory based control technique for series active filter to compensate power-quality (PQ) problems through a three-phase four-wire unified PQ conditioner (UPQC) under unbalanced and distorted load conditions. The proposed UPQC system can improve the power quality at the point of common coupling on power distribution systems under unbalanced and distorted load conditions. The simulation results based on Matlab/Simulink are discussed in detail in this paper.

Optimal Placement of Custom Power Devices in Power System Network to Mitigate Voltage Sag under Faults

Abstract-

Voltage sag has been considered to be a serious power quality problem faced by many utilities. Placement of custom power devices may prove to be an effective remedy for solving power quality problems. In this paper, an Artificial Neural Network (ANN) based approach for optimal placement of Distribution Static Synchronous Compensator (DSTATCOM), Dynamic Voltage Restorer (DVR) and Unified Power Quality Conditioner (UPQC) in a power system network has been considered to mitigate voltage sag under faults. Voltage sag under different type of short circuits has been estimated using MATLAB/SIMULINK software. Optimal location of custom power devices has been obtained using a feed forward neural network trained by post-fault voltage magnitude of three phases at different buses. A comparative performance of DSTATCOM, DVR and UPQC in voltage sag mitigation has been studied to select most effective controller out of three controllers for the system. Case studies have been performed on IEEE 14-bus system. The effectiveness of proposed approach of placement of custom power devices has been established on the test system considered.

Modelling and Analysis of STATCOM Based Voltage Regulator for Self-Excited Induction Generator with Unbalanced Loads

Abstract-

This paper presents an analysis of the three-phase self-excited induction generator (SEIG) with static-compensator {STATCOM) as a voltage regulator. Current controlled voltage source inverter (CC-VSI) is used as STATCOM, which provides fast dynamic response to maintain constant voltage at SEIG terminals during severe load perturbations and acts as a source and sink of reactive power. The performance equations are derived using d-q variable in stationary reference frame to develop a mathematical model of SEIG-STATCOM system feeding unbalanced loads. Transient analysis of the SEIGSTATCOM system is carried out for voltage build-up; switching in STATCOM, application and removal of balanced/unbalanced resistive/reactive loads. The STATCOM compensates the unbalanced load and keeps the generating system balanced while maintaining constant AC terminal voltage.

A Review of Control and Modulation Methods for Matrix Converters

Abstract—

This paper presents a review of the most popular control and modulation strategies studied for matrix converters (MCs) in the last decade. The purpose of most of these methods is to generate sinusoidal current on the input and output sides. These methods are compared considering theoretical complexity and performance. This paper concludes that the control strategy has a significant impact on the resonance of the MC input filter.

A New Method for Islanding Detection of Inverter-Based Distributed Generation Using DC-Link Voltage Control

Abstract—

This paper presents a new method for islanding detection of inverter-based distributed generation (DG). The main idea of this paper is to change the dc-link voltage considering the PCC voltage changes during islanding condition. A simple islanding detection scheme has been designed based on this idea. The proposed method has been studied under multiple-DG operation modes and the UL 1741 islanding tests. The simulations results, carried out by MATLAB/Simulink, show that the proposed method has a small nondetection zone. Also, this method is capable of detecting is-landing accurately within the minimum standard time.

Two Types of KY Buck–Boost Converters

Abstract—

A novel voltage-bucking/boosting converter, named as KY buck–boost converter (i.e., 2D converter), is presented herein. Unlike the traditional buck–boost converter, this converter possesses fast transient responses, similar to the behavior of the buck converter with synchronous rectification. In addition, it possesses the nonpulsating output current, thereby not only decreasing the current stress on the output capacitor but also reducing the output voltage ripple. Furthermore, it has the positive output voltage, different from the negative output voltage of the traditional buck–boost converter. Above all, there are two types of KY buck–boost converters presented herein. In this paper, the basic operating principles of the proposed converters are first illustrated in detail, and second, some experimental results are offered to verify the effectiveness of the proposed topologies.

A Single Phase Matrix Converter for AGPU

Abstract -

This paper designs the single phase matrix converter to obtain a constant 110V/400Hz output, irrespective of the distortions in both the supply and load. The single phase matrix converter employs a safe­commutation strategy, which results in the elimination of voltage spikes on switches, without the need of a snubber circuit. This is facilitated through proper switching control algorithm. Also, an improved control structure for the matrix converter system is devised in the simulation to control the output voltage. The operating principles of this converter are described and the circuit behaviour is confirmed by the MATLAB / Simulink simulation results.

A Zero-Voltage-Switching DC–DC Converter With High Voltage Gain

Abstract—

A zero-voltage-switching (ZVS) dc–dc converter with high voltage gain is proposed. It consists of a ZVS boost converter stage and a ZVS half-bridge converter stage and two stages are merged into a single stage. The ZVS boost converter stage provides a continuous input current and ZVS operation of the power switches. The ZVS half-bridge converter stage provides a high voltage gain. The principle of operation and system analysis are presented. Theoretical analysis and performance of the proposed converter were verified on a 100 W experimental prototype operating at 108 kHz switching frequency.

AC Induction Motor Control Using the Constant V/f Principle and a Space-vector PWM Algorithm