This article presents a novel computational method for the diagnosis of broken rotor bars in three phase asynchronous machines. The proposed method is based on Principal Component Analysis (PCA) and is applied to the stator's three phase start-up current. The fault detection is easier in the start-up transient because of the increased current in the rotor circuit, which amplifies the effects of the fault in the stator's current independently of the motor's load. In the proposed fault detection methodology, PCA is initially utilized to extract a characteristic component, which reflects the rotor asymmetry caused by the broken bars. This component can be subsequently processed using Hidden Markov Models (HMMs). Two schemes, a multiclass and a one-class approach are proposed. The efficiency of the novel proposed schemes is evaluated by multiple experimental test cases. The results obtained indicate that the suggested approaches based on the combination of PCA and HMMs, can be successfully utilized not only for identifying the presence of a broken bar but also for estimating the severity (number of broken bars) of the fault.

Principal Component Analysis of the start-up transient and Hidden Markov Modeling for broken rotor bar fault diagnosis in asynchronous machines

Energy security is one of the most crucial factor in the development of any nation. Interconnections among different power system networks are made to lower the overall price of power generation as well as enhance the reliability and the security of electric power supply. Different types of interconnection technologies are employed, such as AC interconnections, DC interconnections, synchronous interconnections, and asynchronous interconnections. It is necessary to control the power flow between the interconnected electric power networks. The power flow controllers are used to (i) enhance the operational flexibility and controllability of the electric power system networks, (ii) improve the system stability and (iii) accomplish better utilization of existing power transmission systems. These controllers can be built using power electronic devices, electromechanical devices or the hybrid of these devices. In this paper, control techniques for power system networks are discussed. It includes both centralized and decentralized control techniques for power system networks. This paper also presents a comprehensive review of HVDC interconnections, asynchronous AC interconnections, synchronous AC interconnections and different types of power flow controllers used in these interconnections. Moreover, some important and multivariable flexible AC transmission system (FACTS) devices such as UPFC and IPFC are also discussed with their merits and limitations. Finally, a new asynchronous AC link called flexible asynchronous AC link (FASAL) system is also described in detail. At last, a summary of the comparative analysis of power system link and power flow controllers is given based on recent publications. More than 400 research articles and papers on the topic of power transfer control are covered in this review and appended for a quick reference.

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A Comprehensive Review of Power Flow Controllers in Interconnected Power System Networks

A hybrid power system may be used to reduce dependency on either conventional energy or renewable systems. This article deals with the sizing, generator running hours, sensitivity analysis, optimisation, and greenhouse gas emission analysis of hybrid renewable energy systems (HRES). Two locations have been selected where the feasibility of using different hybrid systems is studied for the same load demand. One site is the small remote community of Amini in the Lakshadweep Islands, located in southern India in the Arabian Sea, where solar and/or wind energy is always available throughout the year to provide energy security. Another place is the rural township of Hathras, in the northern Indian state of Uttar Pradesh, where agricultural biomass is found in abundance for the whole year. A comparative study has been made for the two locations for the same load demand by simulating HRES. To achieve the goal of simulation, the hybrid optimisation model for electric renewables (HOMER) software of the National Re...

Optimal hybrid renewable energy systems for energy security: a comparative study

This paper presents a photovoltaic (PV) system parallel connected to an electric power grid with a power factor corrector (PFC) for supplying the DC loads. The operation principles and design considerations for the presented PV system are analyzed and discussed. The balanced distribution of the power flows between the utility and the PV panels is achieved automatically by regulating the output DC voltage of the PFC. Experimental results are shown to verify the feasibility of the proposed topology, which can effectively transfer the tracked maximum power from the PV system to the DC load, while the unity power factor is obtained at the utility side.

Analysis and Design of a Photovoltaic System DC Connected to the Utility With a Power Factor Corrector

Recently, the penetration of renewable energy sources (RESs) into electrical power systems is witnessing a large attention due to their inexhaustibility, environmental benefits, storage capabilities, lower maintenance and stronger economy, etc. Among these RESs, offshore wind power plants (OWPP) are ones of the most widespread power plants that have emerged with regard to being competitive with other energy technologies. However, the application of power electronic converters (PECs), offshore transmission lines and large substation transformers result in considerable power quality (PQ) issues in grid connected OWPP. Moreover, due to the installation of filters for each OWPP, some other challenges such as voltage and frequency stability arise. In this regard, various customs power devices along with integration control methodologies have been implemented to deal with stated issues. Furthermore, for a smooth and reliable operation of the system, each country established various grid codes. Although various mitigation schemes and related standards for OWPP are documented separately, a comprehensive review covering these aspects has not yet addressed in the literature. The objective of this study is to compare and relate prior as well as latest developments on PQ and stability challenges and their solutions. Low voltage ride through (LVRT) schemes and associated grid codes prevalent for the interconnection of OWPP based power grid have been deliberated. In addition, various PQ issues and mitigation options such as FACTS based filters, DFIG based adaptive and conventional control algorithms, ESS based methods and LVRT requirements have been summarized and compared. Finally, recommendations and future trends for PQ improvement are highlighted at the end.

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Offshore Wind Farm-Grid Integration: A Review on Infrastructure, Challenges, and Grid Solutions

Energy is vital input for economy and social development in every society. Presently, the global primary energy demands are met largely from oil, natural gas, coal, nuclear and hydroelectric energy among which coal is dominant. Thermal Power Stations add to environmental degradation problems through gaseous emissions, particulate matter, fly ash, bottom ash, which are very harmful to human life. The proper siting, installation and operation of renewable and non-conventional energy power sources will help to control, replace and avoid adverse environmental impacts. The Carbon Dioxide (CO2) and other gases released by burning fossil fuels contribute to the "green house" effect which cause global climate changes. Renewable energy sources mainly Wind, Small hydro, Biomass and Solar Photovoltaic (SPV) etc. are the most suitable means to achieve the mitigation of CO2 emission. This study gives estimation of CO2 mitigation potential of renewable energy sources in comparison with pollution caused by pulverized coal boilers based thermal power plants. In this paper emissions (kg/KWH) from Indian coal-fired thermal power plants have been calculated by taking emission data from 81 thermal power plants around the country. The total amounts of emission (kg/year) from existing thermal power plants have been estimated and the mitigation of emissions through renewable energy generation have been shown.

Estimation of CO2 Mitigation Potential through Renewable Energy Generation

An interconnection of electric power networks enables decarbonization of the electricity system by harnessing and sharing large amounts of renewable energy. The highest potential renewable energy areas are often far from load centers, integrated through long-distance transmission interconnections. The transmission interconnection mitigates the variability of renewable energy sources by importing and exporting electricity between neighbouring regions. This paper presents an overview of regional and global energy consumption trends by use of fuel. A large power grid interconnection, including renewable energy and its integration into the utility grid, and globally existing large power grid interconnections are also presented. The technologies used for power grid interconnections include HVAC, HVDC (including LCC, VSC comprising of MMC-VSC, HVDC light), VFT, and newly proposed FASAL are discussed with their potential projects. Future trends of grid interconnection, including clean energy initiatives and developments, UHV AC and DC transmission systems, and smart grid developments, are presented in detail. A review of regional and global initiatives in the context of a sustainable future by implementing electric energy interconnections is presented. It presents the associated challenges and benefits of globally interconnected power grids and intercontinental interconnectors. Finally, in this paper, research directions in clean and sustainable energy, smart grid, UHV transmission systems that facilitate the global future grid interconnection goal are addressed.

Electric Power Network Interconnection: A Review on Current Status, Future Prospects and Research Direction

The primary reason for interconnections among different power grids is to reduce the overall economic costs as well as increase reliability and security of supplying electricity services. Thus, for electrical power flow from one power system or grid to another power system or grid a simple, reliable and low cost interconnection is needed. In this paper, a flexible ac power transmission link technology has been proposed for linking two asynchronous independent power systems. The proposed flexible asynchronous ac link (FASAL) system essentially consists of a rotating transformer which is put in the ac tie line between two separate power systems or grids. It controls the power transmission between these power systems which are asynchronous under some or all operating conditions. The direction and the magnitude of power flow is controlled by controlling voltage and/or frequency. Simulink model of proposed FASAL system has been developed for the analytical study and the result verifies the power transfer capability of the proposed system.

Imdadullah

Papers

A Comprehensive Review of Power Flow Controllers in Interconnected Power System Networks

Estimation of CO2 Mitigation Potential through Renewable Energy Generation

Electric Power Network Interconnection: A Review on Current Status, Future Prospects and Research Direction

Flexible asynchronous ac link for power system network interconnection

Comprehensive performance analysis of flexible asynchronous AC link under various unbalanced grid voltage conditions