scholarly journals Fault detection technique for modified cascaded half-bridge multi-level inverter with polarity changer in pv grid system

2021 ◽  
Vol 3 (5) ◽  
Author(s):  
Ujjval B Vyas ◽  
Varsha A Shah ◽  
Srivani S G
Keyword(s):  
Fault Detection ◽  
Search Algorithm ◽  
High Reliability ◽  
Gravitational Search Algorithm ◽  
Detection Algorithm ◽  
Open Circuit ◽  
Fault Isolation ◽  
Photovoltaic System ◽  
Harmonic Elimination ◽  
The Cost

AbstractMultilevel Inverters (MLI) are a viable option for a filter-less and transformerless photovoltaic system for direct grid integration, reducing losses, space and cost provided the issues of control and reliability are resolved. A modified cascaded half-bridge MLI with polarity changer is proposed with a reduced number of switches, thereby reducing control complexity. The proposed converter is designed for both seven-level and nine-level topologies. Selective harmonic elimination has been adopted to switch converter and the transcendental equations are solved by the gravitational search algorithm. The THD for nine-level configuration is 7.94% and 5.86% with MPPT and DC source inputs, respectively. The analysis on the open-circuit fault of switches confirms the presence of only five critical switches irrespective of the number of increase in levels, thereby requiring only five redundant switches at the Polarity Changer. The output voltage waveform is subjected to multiresolution analysis for feature extraction of voltages under various irradiance and temperature conditions. A conditions based fault detection algorithm is developed based on the observations of energies of signals to detect the open circuit fault in switches. Based on the comparative analysis, the proposed converter has fewer controlled switches for nine levels or higher configurations than other topologies. Apart from this, the high reliability due to inherent fault isolation capability restricted to half-bridge compared to different MLI topologies shows its superiority. For a nine-level MLI proposed topology reduces the cost considering redundancies for FDI in range of 67–30% depending on the topology for comparision. The system is simulated using MATLAB –Simulink and further validated by experimental results.

scholarly journals Fault Detection, Isolation And Prognosis For Control Moment Gyros Onboard Satellites

2021 ◽  
Author(s):  
Venkatesh Muthusamy
Keyword(s):  
Fault Detection ◽  
Health Monitoring ◽  
Detection Algorithm ◽  
Fault Isolation ◽  
Remaining Useful Life ◽  
Path Model ◽  
Data Driven ◽  
Chebyshev Neural Network ◽  
Control Moment ◽  
Computational Budget

Developing a Diagnosis, Prognosis and Health Monitoring (DPHM) framework for a small satellite is a challenging task due to the limited availability of onboard health monitoring sensors and computational budget. This thesis deals with the problem of developing DPHM framework for a satellite attitude actuator system that uses a single gimballed Control Moment Gyro (CMG) in pyramid configuration as an actuator. This includes the development of computationally light data-driven model, fault detection, isolation and prognosis algorithms that works only using the attitude rate measurements from the satellite. A novel scheme is proposed for developing a data-driven model which fuses the symmetric property of the data and the system orientation property of actuators that reduces the need for historical data by 93.75%. The data is trained using Chebyshev Neural Network. A threshold based fault detection algorithm is used to detect the faults of spin motor and gimbal motor used in a CMG. A novel optimization based fault isolation formulation is developed and simulated for given uniformly distributed system parameters. The algorithm has a success rate of 93.5% in isolating faults of 8 motors (4 gimbal and 4 spin) that can fail in 254 different ways. For Fault Prognosis, an error based scheme is developed as a measure of degradation. General path model with Bayesian updating is used for predicting the remaining useful life of the spin motor. It performs with 96.25% accuracy when 30% of data is available. Overall, the proposed algorithms can be regarded as a promising DPHM tool for similar non-linear systems.

scholarly journals Risk Response Selection in Construction Projects

2018 ◽  
Vol 3 (12) ◽  
pp. 1208 ◽  
Author(s):  
Hafeth I. Naji ◽  
Rouwaida Hussein Ali
Keyword(s):  
Risk Management ◽  
Optimal Strategy ◽  
Construction Projects ◽  
Response Selection ◽  
Search Algorithm ◽  
Gravitational Search Algorithm ◽  
Response Strategy ◽  
Risk Response ◽  
Gravitational Search ◽  
The Cost

Risk and its management  is  important  for the success of the project, the  risk management, which encompassed of planning, identification, analysis, and response has an important phase, which is risk response  and it should not be undermined, as its  success going to  the projects  the capability  to overcome the  uncertainty and  thus an effective  tool in project risk management, risk response used the collective information in the analysis stage and in order  to take decision how to improve the possibility to complete the project within time, cost and performance. This stage work on preparing the response to the main risks and appoint the people who are responsible for each response.  When it's needed risk response may be started in quantitative analysis stage and the repetition may be possible between the analysis and risk response stage. The aim of this research is to provide a methodology to make the plane for unexpected events and control uncertain situations and identify the reason for risk response failure and to respond to risk successfully by using the optimization method to select the best strategy. The methodology of this research divided into four parts, the first part main object is to find the projects whose risk response is failed, the second part includes the reasons for risk response Failure, the third part includes   finding   the most important risks generated from risk response that leads to increasing the cost of construction projects, the fourth part of the management system is selecting the optimal risk response strategy. An optimization model was used to select the optimal strategy to treat the risk by using Serval constraints such as the cost of the project, time of the project, Gravitational Search Algorithm and particle swarm used. The result of the risk response selection shows that The investment (contractor, bank) strategy shows a very good strategy as it saves the cost about 30%, while the Mitigate (pay for advances with interest 0. 1) Strategy show saving the cost 40%   and giving land to contractors show saving the cost 40% finally the BIM strategy show saving the cost 25%. The risk response is an important part and should give a great attention and it must be used sophisticated method to select the optimal strategy, the two techniques both show high efficiency in selecting the strategy but Gravitational Search Algorithm show better performance.

Fault Detection, Isolation And Prognosis For Control Moment Gyros Onboard Satellites

2021 ◽  
Author(s):  
Venkatesh Muthusamy
Keyword(s):  
Fault Detection ◽  
Health Monitoring ◽  
Detection Algorithm ◽  
Fault Isolation ◽  
Remaining Useful Life ◽  
Path Model ◽  
Data Driven ◽  
Chebyshev Neural Network ◽  
Control Moment ◽  
Computational Budget

Developing a Diagnosis, Prognosis and Health Monitoring (DPHM) framework for a small satellite is a challenging task due to the limited availability of onboard health monitoring sensors and computational budget. This thesis deals with the problem of developing DPHM framework for a satellite attitude actuator system that uses a single gimballed Control Moment Gyro (CMG) in pyramid configuration as an actuator. This includes the development of computationally light data-driven model, fault detection, isolation and prognosis algorithms that works only using the attitude rate measurements from the satellite. A novel scheme is proposed for developing a data-driven model which fuses the symmetric property of the data and the system orientation property of actuators that reduces the need for historical data by 93.75%. The data is trained using Chebyshev Neural Network. A threshold based fault detection algorithm is used to detect the faults of spin motor and gimbal motor used in a CMG. A novel optimization based fault isolation formulation is developed and simulated for given uniformly distributed system parameters. The algorithm has a success rate of 93.5% in isolating faults of 8 motors (4 gimbal and 4 spin) that can fail in 254 different ways. For Fault Prognosis, an error based scheme is developed as a measure of degradation. General path model with Bayesian updating is used for predicting the remaining useful life of the spin motor. It performs with 96.25% accuracy when 30% of data is available. Overall, the proposed algorithms can be regarded as a promising DPHM tool for similar non-linear systems.

scholarly journals Threshold value of DC array current and DC string voltage for fault detection in grid-connected photovoltaic system

2020 ◽  
Vol 17 (1) ◽  
pp. 1
Author(s):  
Nurmalessa Muhammad ◽  
Nor Zaini Ikrom Zakaria ◽  
Sulaiman Shaari ◽  
Ahmad Maliki Omar
Keyword(s):  
Fault Detection ◽  
Failure Detection ◽  
Threshold Value ◽  
Detection Algorithm ◽  
Green Energy ◽  
Photovoltaic System ◽  
Energy Output ◽  
Climate Data ◽  
Pv System ◽  
Loss Analysis

The failure detection in a grid-connected photovoltaic (PV) system has become an important aspect of solving the issue of the reduced energy output in the PV system. One of the methods in detecting failure is by using the threshold-based method to compute the ratio of actual and predicted DC array current and DC string voltage value. This value will be applied in the failure detection algorithm by using power loss analysis and may reduce the time, cost and labour needed to measure the quality of the energy output of the PV system. This study presented the threshold value of DC array current and DC string voltage to be implemented in the algorithm of fault detection in grid-connected photovoltaic (PV) system under the Malaysian climate. Data from the PV system located at Green Energy Research Center (GERC) was recorded in 12 months interval using the monocrystalline PV modules. The actual data was recorded using five minutes interval for 30 consecutive days. The prediction of the data was calculated using the mathematical method. The threshold value was determined from the ratio between actual and predicted data. The results show that the DC array current threshold value, σ is 0.9816. While, DC string voltage threshold value, λ is 0.9261. The proposed value may be beneficial for the determination of threshold value for regions with the tropical climate.

Fault-Tolerant Voltage Source Converter for Wind-Driven Doubly Fed Induction Generator Connected to a DC Load

2018 ◽  
Vol 27 (10) ◽  
pp. 1850153 ◽  
Author(s):  
Bilel Touaiti ◽  
Hechmi Ben Azza ◽  
Mongi Moujahed ◽  
Mohamed Jemli
Keyword(s):  
Fault Detection ◽  
Fault Tolerant ◽  
Open Circuit ◽  
Photovoltaic System ◽  
Voltage Source ◽  
Induction Generator ◽  
Voltage Source Converter ◽  
Doubly Fed Induction Generator ◽  
Detection Scheme ◽  
Doubly Fed

This paper presents a fault-tolerant Voltage Source Converter (VSC) for Field Oriented Control (FOC) of a stand-alone Doubly Fed Induction Generator (DFIG) connected to a DC load. In the proposed topology, the stator of the DFIG is connected to a DC load through a diode rectifier, while the rotor is connected to the DC load through a VSC. This topology allows the integration of DFIG in the hybrid system with other sources of production and storage, such as photovoltaic system, connected to the same DC bus. The fault-tolerant VSC consists in incorporating a fourth leg to replace the faulted leg. A fault detection scheme for switch device open-circuit faults is proposed in this study. The novelty of this method consists in analyzing the rotor currents within normal and faulty operating modes. Simulation results are presented for a 3.7[Formula: see text]kW DFIG-DC system with single open-circuit faults that validate the methods presented in this study. The effectiveness of the proposed fault detection method has been validated experimentally by using dSpace DS1104 control board based on TMS320F240 real time Digital Signal Processor (DSP).

scholarly journals Mil-Std 1553 Cable Modeling for Fault Detection

2020 ◽  
Vol 9 (4) ◽  
pp. 1648-1655
Keyword(s):  
Fault Detection ◽  
Public Transportation ◽  
High Speed ◽  
Power Transmission ◽  
Detection System ◽  
Short Circuit ◽  
Detection Algorithm ◽  
Open Circuit ◽  
Test Signal ◽  
Prototype Development

Amongst major industries, the aircraft industry has gained momentum not only in public transportation, but also in defence, business and space sectors. The electrical, mechanical and electronic systems of an aircraft are all interconnected by different types of cables like hook up wires, cables for high speed data transmission, cables for power transmission, fire resistant cables, co-axial cables etc , with each type of cable having its own specifications. Military Standard 1553 (Mil-Std 1553) is one such cable primarily used for on-board aircraft sub-system communication and monitoring. Mil-Std 1553 protocol defines the physical and electrical properties of the cable. Mil-Std 1553 is a dual redundant bus, that is, there are two channels for a single bus communication. Mil-Std 1553 is prone to faults like opens or shorts because of its continuous wear and tear in aircraft environment. If a faulty cable is operated, then it possesses a high risk to the aircraft system .As of now ,there is no automatic fault detection system employed on Mil-Std 1553. Hence there is a need for automatic fault detection system on Mil-Std 1553 cables before the entire system collapses. In this regard, modeling of Mil-Std 1553 is very important since the developed model can be used for testing of the fault detection algorithm and further prototype development. Here, the Mil-Std 1553 cable has been modeled using SIMULINK/MATLAB. The cable is modeled under two different scenarios: considering only the Test Signal , considering both Test Signal and Data Signal. The cable is modeled considering all its electrical characteristics for three conditions, namely, No Fault condition, Open circuit condition and Short circuit condition. PI section is used as an elemental block for modeling of Mil-Std 1553.

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