Genetic diversity of Xanthomonas oryzae pv. oryzae strains from rice fields in Malaysia.

Bacterial leaf blight caused by Xanthomonas oryzae pv oryzae (Xoo) is one of the most important bacterial diseases of rice, first detected in Japan in 1884. Repetitive extragenic palindromic (REP) and enterobacterial repetitive intergenic consensus (ERIC) assays were used to differentiate the phylogenetic relationships among 30 Xoo strains collected from rice fields in the states of Penang, Kedah, Selangor and Melaka (Peninsular Malaysia), during the period 2008-2010. Analysis of the 30 strains with REP and ERIC primers yielded five major amplification bands ranging from 200 to 800 bp in size. Fingerprints determined for each strain contained in total a maximum of 16 reproducible bands and a minimum of 9, ranging from 100 to 2,800 bp. The maximum number of score bands was observed in strains from Melaka and the minimum in strains from Penang and Kedah. Cluster analysis of the results of Rep PCRs yielded two major clusters and five sub clusters. Similarity between the two main clusters was 60% and 75% between five subclusters. This indicates that although there is a phylogenetic relation among strains of Xoo from rice crops of Peninsular Malaysia, nevertheless strains from different geographic regions are phylogenetically diverse

Fault location and classification of combined transmission system: Economical and accurate statistic programming framework

An effective statistical feature extraction approach of data sampling of fault in the combined transmission system is presented in this paper. The proposed algorithm leads to high accuracy at minimum cost to predict fault location and fault type classification. This algorithm requires impedance measurement data from one end of the transmission line. Modal decomposition is used to extract positive sequence impedance. Then, the fault signal is decomposed by using discrete wavelet transform. Statistical sampling is used to extract appropriate fault features as benchmark of decomposed signal to train classifier. Support Vector Machine (SVM) is used to illustrate the performance of statistical sampling performance. The overall time of sampling is not exceeding 1¼ cycles, taking into account the interval time. The proposed method takes two steps of sampling. The first step takes ¾ cycle of during-fault and the second step takes ¼ cycle of post fault impedance. The interval time between the two steps is assumed to be ¼ cycle. Extensive studies using MATLAB software show accurate fault location estimation and fault type classification of the proposed method. The classifier result is presented and compared with well-established travelling wave methods and the performance of the algorithms are analyzed and discussed

A control scheme to improve the power quality with the absence of dedicated compensation devices in microgrid

In this paper, a new method is proposed to control the interface Inverter of distributed generators (DGs) in a microgrid. The objective of this method is to effectively compensate for the harmonic currents at the Point of Common Coupling (PCC) and the MG with the Absence of dedicated compensation devices, such as Active Power Filters (APFs). The proposed control method is composed of the Adjustable Synchronous Reference Frame (ASRF) and the Synchronous Reference Frame (SRF) methods. The ASRF and SRF are proposed to control the power injection and harmonic current compensation, respectively. The merged control methods are proposed for the interface inverter to perform the comprehensive activity of compensating for the harmonics, such as a correction of the system imbalance and the removal of the harmonics. The operation principle of the proposed control method is analyzed in detail, and its effectiveness is validated through simulation results

Control of compensation devices by synchronous reference frame and fourier control methods to improve the power quality in a microgrid

The present study used passive filters (PF) and designed Active Power Filters (APFs) with two control methods: synchronous reference frame control and Fourier methods. Studies in the domain of microgrids include distributed generation sources and non-linear loads. Distributed Generation Sources (DGs) include Micro-Turbine (MT) and Fuel Cell (FC), which act as a source of harmonic currents with non-linear loads. To achieve this goal, passive filters are applied to cancel the main harmonics and to provide reactive power, whereas SAPFs are applied to adjust system imbalances and remove the remaining harmonics in the system. The results show that the method can reduce the harmonic disturbances of the system from 24.27% to less than 5%. In addition, this study analyzes how the various control methods operate on active filters. The proposed method has been validated experimentally, and the results are in agreement with the simulation results

Designed a new compensation current control method for three-phase grid-connected photovoltaic inverter

This article proposes a New Compensation Current Control Method for Three-Phase Grid-Connected Photovoltaic Inverter. Our proposed grid-connected power converter consists of a switch mode DC-DC boost converter and an H-bridge inverter. The control method designed to eliminate main harmonics and also is responsible for the injection power to the grid. The proposed control method is comprised of the advance synchronous reference frame method (ASRF). The simulations for three-phase Bridge type inverter have been done in MATLAB/Simulink. To validate the simulation results, a scaled prototype model of the proposed inverter has been built and tested

Improved control of shunt active power filter using harmony search algorithm

This paper proposes to optimize the control parameters of DC-link voltage shunt active power filter (SAPF) by Harmony Search Algorithm (HSA) and Total Harmonic Distortion (THD) reduction in the system. The aim is motivated by the need to minimize the burden on the DC-link capacitor voltage to enhance performance of a shunt active power filter. In particular the attention has been focused on the Hybrid Compensation (HC), including an active filter and Passive Filter (PF) distributed in Micro-Grid (MG) system. Each passive filter has been designed to eliminate main harmonics; connected to nonlinear load and Dispersed Generation Sources (DGSs) and gain reactive power while it is the duty of active filter with instantaneous power theory (pq), to correct unbalanced system as well as eliminate harmonic left. Simulation results are presented to validate the proposed scheme

A New Compensation Control Strategy for Grid-connected Wind Turbine and Fuel Cell Inverters in a Microgrid

The use of a new control method for grid-connected inverters for reducing the output current harmonic distortion in a wide range of grid-connected distributed generation (DG) applications, including wind turbine (WT) and fuel cell (FC) inverters is proposed in this paper. The control method designed to eliminate main harmonics in a microgrid (MG) and between MG and point of common coupling (PCC) and responsible for the correction of the system unbalance. Another advantage of the proposed control method is that it can be easily adopted into the DG control system without the installation of extra hardware. The proposed control method is comprised of the synchronous reference frame method (SRF). Results from the proposed control method are provided to show the feasibility of the proposed approach

A protection strategy for micro-grids based on positive-sequence impedance

In recent years, the concept of micro-grid has appeared as an appropriate way for the integration of Distributed Energy Resources (DERs) in the distribution networks. However, micro-grids have encountered a number of challenges from control and protection aspects. One of the main issues relevant to the protection of micro-grids is to develop a suitable protection technique which is effective in both grid-connected and stand-alone operation modes. This article presents a new micro-grid protection strategy based on positive-sequence impedance using Pha-sor Measurement Units (PMUs) and a designed Microprocessor-Based Relay (MBR) along with a narrowband communication system (only to exchange digital information, not electrical power). The main attribution of the proposed scheme is that it has the ability to protect micro-grids containing either radial or looped feeders; additionally, the capabilities of automatic updating of pick-up threshold value and single-phase tripping have been considered in the designed MBR. Finally, in order to verify the effectiveness of the suggested scheme and the designed MBR, several simulations have been undertaken by using DIgSILENT Power-Factory and Matlab software packages