Drive Systems

Transformerless grid-connected inverters with highly efficient and reliable inverter concept (HERIC) and positive-negative neutral point-clamped (PN-NPC) circuit configurations exhibit excellent performance in terms of overall efficiency, common-mode voltage, and alleviated leakage current concern. These inverters are designed to generate only a three-level (3L) output voltage waveform, thereby reducing the power density of a conversion system. On the other hand, it is well-known that increasing the inverter output voltage levels entails the reduction of the output filter size. In this regard, this article aims to develop a five-level (5L) inverter output voltage for the improved versions of HERIC-clamped and original PN-NPC inverters. This is achieved with either phase-shifted or level-shifted pulse width modulation technique leading to further quality improvement of ac voltage and current waveforms through increasing the number of output voltage levels. Therefore, a much smaller output filter size can be utilized, while the overall efficiency of the entire system is enhanced. Two laboratory-built SiC-based prototypes for both the proposed HERIC-clamped (1.8 kW) and PN-NPC-5L (2 kW) inverters have been fabricated to show the feasibility and effectiveness of the proposed solution via experiments. INDEX TERMS HERIC-clamped inverter, multilevel inverters, PN-NPC inverter, pulse width modulation (PWM).

Distributed generation systems integrated into the modern electrical grid demand novel circuit architectures that can combine high efficiency and high power density together. The transformerless highly efficient and reliable inverter concept (HERIC) topologies are notable due to their mitigated leakage current concerns, constant common-mode voltage, and high efficiency. Nonetheless, the HERIC-based structures feature a maximum of three-level ac output voltage, forcing the conversion system to integrate large output filters to meet the grid codes. This article introduces a novel HERIC active-clamped converter with bidirectional power flow and full reactive power capabilities that can achieve five-level output voltage. This is accomplished by means of a phase-shifted pulsewidth modulation technique that effectively doubles the apparent switching frequency of the inverter and improves the quality of the injected ac power. Consequently, the topology can achieve higher power conversion efficiency, while using the same or a smaller output filter. To verify the feasibility of the proposed converter, a 2.5-kW SiC-based prototype was built and tested in the laboratory under different operation conditions. INDEX TERMS Highly efficient and reliable inverter concept (HERIC)-clamped inverter, multilevel inverters, power converters, pulsewidth modulation inverters (PWM).

In PV systems grid-connected, we always have to work with power electronics modules. For safety, any design of power electronics converter should be simulated carefully in order to prevent from serious damages from high voltage, high current which can cause fire, explosion. By using hardware-in-the-loop (HIL) simulation, we could make sure the converter would operate the right way, which is not always achieve on the real hardware design when the first attempt, so that we can reduce ricks and furthermore reduce product development time and cost. After success on simulation, it will be not much complex to implement the algorithm to the real hardware. This paper presents the process for designing the HERIC inverter by using PSIM software which can be simulate and generate the project code for implement to the floating point DSP: TMS320F28335. The HERIC (Highly Ef cient and Reliable Inverter Concept) inverter is used in the design because of its advantages: high efficiency and safety by reducing the leakage ground current when the inverter is connected to the national grid without using a transformer. The algorithm was executed by the chip TMS320F28335 high performance up to 150MHz with a mathoptimized core. The process produced in this paper can be applied for any design idea about a high power, high efficiency power electronics converter.

Voltage source converters (VSCs) have revolutionized high voltage direct
current (HVDC) transmission, offering numerous advantages such as black
start capability, absence of commutation failure, and efficient control of
bidirectional power flow. This study introduces a comparative analysis of
advanced VSC technologies, focusing on a novel series hybrid converter
incorporating an inductor-capacitor-inductor (LCL) passive circuit. This
configuration is explored for its potential to enhance both high voltage
alternating current (HVAC) and high voltage direct current (HVDC) side
fault suppression capabilities and improve DC output voltage quality,
addressing critical drawbacks of traditional VSCs. Through comprehensive simulations in MATLAB/Simulink, this research evaluates and compares three different converter topologies: the three-level neutral point clamped converter, the hybrid converter with AC side cascaded H-bridge cells, and the LCL hybrid converter. The comparison is based on key performance metrics such as DC output voltage quality, fault suppression capabilities, and system efficiency during normal and fault conditions. The study finds that the LCL hybrid converter outperforms traditional converters by significantly improving DC output voltage quality and enhancing fault suppression capabilities in HVDC systems. It effectively reduces ripple and maintains stability during faults, making it a superior choice for future HVDC converter designs and applications, offering valuable insights for advancing HVDC technology.

Generally, PV systems are need of the hour from electrical energy system point of view. This paper also proposes the concept of hybrid grid energy system which consists of photovoltaic system. And also an Incremental Conductance MPPT technique is proposed in order to improve the photovoltaic power. The performance of this hybrid system is observed by simulation case study demonstrate the usefulness of the proposed system

Complex control structures are required for the operation of photovoltaic electrical energy systems. In this paper, a general review of the controllers used for photovoltaic systems is presented. This entry is based on the most recent papers presented in the literature. The control architectures considered are complex hybrid systems that combine classical and modern techniques, such as artificial intelligence and statistical models. The main contribution of this paper is the synthesis of a generalized control structure and the identification of the latest trends. The main findings are summarized in the development of increasingly robust controllers for operation with improved efficiency, power quality, stability, safety, and economics.

A wind energy conversion system run by a variable speed wind turbine having pitch mechanism and two mass direct driven permanent magnet synchronous generator is implemented in this paper. Multilevel inverter is an emerging power technology recently for high-medium application. Out of different topologies, cascaded H bridge multilevel inverter is implemented with WECS as it requires fewer components as compared to other multilevel inverter. One of the major limitations is the use of separate dc source for each H Bridge in cascaded multilevel inverter which can be overcome by inserting isolation transformer. For generation of seven level controlled output voltages, a phasemulti-carrier pulse width modulation is used. The proposed WECS having seven-level inverter having isolation transformers is simulated in MATLAB/SIMULINK. The simulated waveform of the output obtained from PMSG, DC link voltage, Pitch angle and three phase CHB MLI voltages are shown.

, 84 pages Energy availability is a growing concern of the 21 st century worldwide and generating this energy should not affect the envinment and its inhabitants negatively. The modern energy transmission and distribution system became more interesting with the advent of smart grid and integrating renewable energy sources into the grid creates a challenging problem of managing harmonics. To effectively integrate renewable energy as well as minimizing harmonics content in the power system smart grid importance was highlighted, with value of harmonic current content measured by the total harmonic distortion (THD) based on electrical system rated current value. This thesis is aimed towards reviewing the available techniques in reducing the harmonic distortions for effective and efficient transmission of renewable energy in smart grid integration. The use of an improved control strategy was proposed which significantly improves the effectiveness of harmonic elimination in smart grid systems. The two-level and there-level inverters in solar integration to the smart grid were studied, thereby presented a controlled hydrid filtering technique

The energy paradigms in many countries (e.g. Germany and Denmark) have experienced a significant change from fossil-based resources to clean renewables (e.g. wind turbines and photovoltaics) in the past few decades. The scenario of highly penetrated renewables is going to be further enhanced-Denmark expects to be 100 % fossil-free by 2050. Consequently, it is required that the production, distribution and use of the energy should be as technologically efficient as possible and incentives to save energy at the end-user should also be strengthened. In order to realize the transition smoothly and effectively, energy conversion systems, currently based on power electronics technology, will again play an essential role in this energy paradigm shift. Using highly efficient power electronics in power generation, power transmission/distribution and end-user application, together with advanced control solutions, can pave the way for renewable energies. In light of this, some of the most emerging renewable energies, e.g. wind energy and photovoltaic, which by means of power electronics are changing character as a major part in the electricity generation, are explored in this paper. Issues like technology development, implementation, power converter technologies, control of the systems, and synchronization are addressed. Special focuses are paid on the future trends in power electronics for those systems like how to lower the cost of energy and to develop emerging power devices and better reliability tool.

Tremendous promotion and growth of Large-Scale Solar Photovoltaic (LSSPV) Power Plant in Malaysia increase the reliability and potentiality of the system in having efficient monitoring, operation and maintenance for the plants. Through the Ministry of Energy, Science and Technology, the government aims to increase the renewable energy in its generation mix in 2025 by 20% and intends to reduce its greenhouse gas (GHG) emission intensity per unit of gross domestic product (GDP) to 45% by 2030. This was followed by the Energy Commission (EC) announcement of 500 MW LSSPV power plants in Malaysia, slated for commercial operation in 2021. Thus, proper monitoring and respectable power generation are crucial to optimising LSSPV for grid interconnection. This paper presents the assessment of string inverters configuration and analysis models to recommend an optimised configuration for maximum harvested power generation in the LSSPV power plant in Malaysia. An analysis of string invert config...

All the RE systems require specific power electronic converters to convert the power generated into useful power that can be directly interconnected with the utility grid and/ or can be used for specific consumer applications locally. The roles of these power converters become very critical, particularly when it is used in one of the most expensive energy generating sources such as solar PV. Since power converter/inverter are the interface of the distributed power system, any premature failure of such system will make the entire system defunct and thus need to be selected appropriately. These power converters need to be selected and designed optimally in order to provide maximum energy efficiency, ensuring reliability and safety of the overall solar PV system, required for different applications. This paper focuses on classification of inverters and present how an best fit inverter can be selected for a particular distributed solar PV applications based on its control scheme, PV array configurations, operational and safety features etc. The paper also covers the review of inverters and brings out few findings on the performance of various existing inverters available in the market based on a systematic analysis done by the author.  Index Terms-solar photovoltaic, inverter, control scheme, central inverter, string inverter, review of inverter

This paper proposes a complete distributed model for investigating both the induced shaft voltage and bearing current in turbo generators due to the interaction with their static excitation systems. This affects the insulations gradually, leading to a possible electrical discharge current when the shaft voltage exceeds the dielectric breakdown voltage level of the lubricating grease film in journal bearings. Furthermore, a buck converter is proposed to overcome the stated issue, where simulations confirm the effectiveness of the proposals.

This paper proposes a complete distributed model for investigating the induced shaft voltage and bearing current in turbo generators due to the interaction with the static excitation systems. This undesirable voltage affects the insulations gradually, lowering the life expectancy of the whole system. If the shaft voltage exceeds the dielectric breakdown voltage level of the lubricating grease film in journal bearings, an electrical discharge current flows through the bearings. In order to inspect the shaft voltage, a passive filter is proposed to overcome the stated issue. Both the proposed model and the passive filtering technique are simulated with SIMULINK, and discussed in detail to confirm the presence of the bearing current and shaft voltage.

The direct torque control-space vector modulation (DTC-SVM) is well-known for achieving excellent dynamic overmodulation. However, the method uses complicated predictive stator flux vector control and requires high precision stator flux vector to define overmodulation mode. This paper proposes a straightforward dynamic overmodulation method and constant switching frequency controller without SVM to obtain a faster dynamic torque response in DTC for induction machines. To perform this, the flux error status produced from the flux hysteresis comparator during dynamic condition is modified slightly before being fed to the look-up table. The verification of proposed method was performed using MATLAB/Simulink simulation package. The effects of different switching and operating condition on dynamic torque performance are analyzed. The result shows that a faster torque response is achieved in proposed dynamic overmodulation DTC method. The main benefit of the proposed method is its simplicity since only minor modification is made to the basic DTC hysteresis-based structure.

This paper deals with design of a synchronous frame control strategy for single-phase inverter-based islanded distributed generation (DG) systems. Although, implementation of these regulators requires a minimum of two independent phases in the system, the required orthogonal phase is generated through the use of a first order all pass filter (APF). The essence of the proposed control strategy is to use a synchronous reference frame PI (SRFPI) controller to regulate output voltage, together with a simple inner capacitor current regulating loop to stabilize the system and a voltage-feedforward loop to improve the system robustness. A detailed design criterion for the proposed control strategy is presented base on a frequency-response approach. Finally, simulation results are presented to validate the proposed method.

International audienceThis paper focuses in the optimization of the efficiency of photovoltaic power conversion chain; we present the optimization of the efficiency of photovoltaic power conversion chain. In this way, we present a new alternative for improving both the performance of photovoltaic (PV) systems and the efficiency of the energy conversion by using different configuration of power converters. Different type's improvements have been proposed of architecture in order to choose the correct PV architecture for each PV installation on the efficiency improvement in all power conversion level stages between PV cells and loads. In this context, this work presents the study and adaptive simulation of photovoltaic systems with micro inverters configurations for applications of renewable energy. We performed comparative between a central and distribution connection of converter via an adaptation floor with Maximum Power Point Tracker (MPPT) control. For thisreason, it is impor...

Nowadays there is need of alternate energy sources due to the paucity of non-renewable energy sources. Because of which they're moving towards renewable energy sources. This paper presents the efficient use of solar power by operating Photovoltaic (PV) panels at the utmost point (MPP) for powering a induction motor drive. The proposed system implemented the appliance to offer power from solar power to induction motor drive by converting the DC electrical power generated from a PV panel to AC power using the resonant inverter. When the switches are turned on and off, a standard inverter generates switching loss due to the hard switching. Thus, the inverter loss is increased. Proposed system contains auxiliary circuit. The converter stage switches perform soft switching due to the resonant circuit. Hence, the system reduces switching loss and voltage stress.

This paper proposes a decentralized control scheme for controlling active and reactive power of grid-tied AC-stacked PV inverter architecture using single member phase compensation. Reactive power control is required for the next generation of grid-tied smart PV inverter systems in power networks with high PV penetration. The decentralized control scheme proposed in this paper allows for a fully distributed architecture, both in terms of active and reactive power control and physical implementation of a PV system. This will result in higher reliability and potentially lower cost with minimum communications requirements. A decentralized controller enables higher switching frequencies which can shrink passive components. Therefore, string voltage variations due to voltage drop across passive components will be negligible and the system will be controlled with minimum communications requirement. The Relative Gain Array approach has been used to study the feasibility of decentralized control scheme. Detailed modeling and analysis are provided to show the effectiveness of the proposed decentralized approach and effect of this approach on control implementation. Finally, effectiveness of the proposed decentralized approach is verified using mathematical modeling, simulation and a lab-scale experimental setup in different operation conditions.

In this paper, an experimental verification of the control of a modular series connected voltage source converter suitable for an HVDC transformerless offshore wind turbine is presented. The test bench is built around a 45 kW special generator prototype with three stator segments. Three 20 kW voltage source converter modules were used in the series connected converter. The experimental results verified the feasibility of a modular, decoupled control system design approach which has earlier been investigated through simulations. In addition, the experimental results are compared to simulations to verify the model implemented in EMTDC/PSCAD.

Multi-rotor wind turbines (MRWTs) have been suggested in the literature as a solution to achieving wind turbine systems with capacities greater than 10 MW. MRWTs utilize a large number of small rotors connected to one support structure instead of one large rotor with the aim of circumventing the square cube law. Potential benefits of MRWTs include cost and material savings, standardization of parts, increased control possibilities, and improved logistics for assembly and maintenance. Almost all previous work has focused on mechanical and aerodynamic feasibility, with almost no attention being paid to the electrical systems. In this research eight different topologies of the electrical collection network for MRWTs are analysed to assess which are the most economically and practically viable options. AC and DC collection networks are presented in radial, star, cluster and DC series topologies. Mass, capital cost and losses are estimated based on scaling relationships from the academic literature and up-to-date commercial data. The focus of this study is the assessment of the type of electrical collector topology, so component type and voltage level are kept consistent between topology designs in order to facilitate a fair comparison. Topologies are compared in terms of four main criteria: capital cost, cost effectiveness, total mass and reliability. A comparison table is presented to summarize the findings of the research in a convenient way. It is found that the most cost-effective solutions are the AC radial and AC star topologies, with the least cost-effective being the DC series-parallel and DC cluster topologies. This is due to the high cost of DC-DC converters and DC switchgear along with the lower efficiency of DC converters. Radial designs perform best in terms of efficiency and annual energy capture. DC systems achieve a slightly lower nacelle mass compared to their equivalent AC systems. DC topologies are generally found to be more expensive when compared to their AC counterparts due to the high cost of DC-DC converters and DC switchgear. Star topologies are considered to have the best reliability due to having no shared equipment. The most suitable collection topology for MRWTs is shown to be of the star type, in which each turbine is connected to the step-up transformer via its own cable.

Tremendous promotion and growth of Large-Scale Solar Photovoltaic (LSSPV) Power Plant in Malaysia increase the reliability and potentiality of the system in having efficient monitoring, operation and maintenance for the plants. Through the Ministry of Energy, Science and Technology, the government aims to increase the renewable energy in its generation mix in 2025 by 20% and intends to reduce its greenhouse gas (GHG) emission intensity per unit of gross domestic product (GDP) to 45% by 2030. This was followed by the Energy Commission (EC) announcement of 500 MW LSSPV power plants in Malaysia, slated for commercial operation in 2021. Thus, proper monitoring and respectable power generation are crucial to optimising LSSPV for grid interconnection. This paper presents the assessment of string inverters configuration and analysis models to recommend an optimised configuration for maximum harvested power generation in the LSSPV power plant in Malaysia. An analysis of string invert config...

In this paper, the dynamic modeling of the studied micro grid (MG) is presented for steady state and transient operation conditions. Moreover, control strategies to obtain the maximum converted power and stabilize the voltage under different operating conditions are derived. The integrated system under study has four key subsystems to supply the required electric loads. The first and second subsystems include the layout of the studied MG and the renewable generation sources from Wind turbine and PV array. The third represents the boost converter between the PV and the DC collection bus as well as the interfaced inverter to the point of common coupling (PCC) with the MG. The fourth subsystem comprises mainly the required PI controllers to regulate the modulation index of the inverter and the duty cycle of the boost converter for PV maximum in addition of regulating the boost inverter DC link voltage. The proportional and integral parameters of these controllers are tuned off-line to enhance the grid performance. The integrated system and the associated subsystems are fully validated for efficient operation under normal or fault conditions using the Matlab/Simulink/Sim-Power software.

An integrated scheme of wind and fuel cell renewable energy technologies in distribution networks for electrical energy generation from renewable resources is digitally simulated and presented in this paper. The integrated system has four key subsystems or components to supply the required electric loads. The first subsystem includes the renewable generation sources from Wind turbines and fuel cell stacks. The second represents the added inverter between the Fuel cell collection DC bus and the point of common coupling PCC with the AC distribution network. The third device is the static synchronous compensator STATCOM to provide the required reactive power for voltage regulation at the bus of PCC. The fourth subsystem comprises mainly of two PI controllers. The first controller main function is to regulate the hydrogen flow to the fuel cell, while the second one is used to control the switching action of the STATCOM converter for injecting the required reactive power. The integrated system and the associated subsystems are fully validated for efficient operation under normal or fault conditions using the Matlab/Simulink/Sim-Power software environment.

In the conventional grid-connected Wind Energy Conversion System (WECS), the generator side inverter is typically controlled via Field Oriented Control (FOC), while Voltage Oriented Control (VOC) controls the grid side inverter. However, robust operation cannot be guaranteed during sudden changes in wind speeds and weak grid connections. This paper presents a novel method to improve the overall dynamic performance of on-grid induction machine-based wind generators. An online mechanical parameter estimation technique is devised using Recursive Least Squares (RLS) to compute the machine inertia and friction coefficient iteratively. An adaptive feedforward neural (AFN) controller is also proposed in the synchronous reference frame, which is constructed using the estimated parameters and the system's inverse. The output of the neural controller is added to the output of the speed PI controller in the outer loop of the FOC to enhance the speed response of the wind generator. A similar approach is taken to improve the classical VOC structure for the grid-side inverter. In this case, the RLS estimates the equivalent Thevenin's grid impedance in real-time. As for the adaptive action, two identical neural networks are integrated with the inner loop direct and quadrature axis current PI controllers. Under nominal operating conditions, it is observed that the PI+AFN provides a faster settling time for the generator's speed and torque response. Upon being subjected to variations in the wind speed, the PI+AFN outperforms the classical PI controller and attains a lower integral-time error. In addition, the proposed PI+AFN controller has a better ability to maintain the grid-side inverter stability during stochastic variations in grid impedance. One significant advantage of the proposed control approach is that no data for training or validation is required since the neural network weights are directly the output of the RLS estimator. Hardware verification for the improved FOC for wind generators using the adaptive controller is also made using the DSPACE 1007 AUTOBOX platform. INDEX TERMS Wind energy conversion, induction generator, grid-connected wind turbine, machine inertia, friction coefficient, grid impedance, feedforward controller, adaptive neural networks, recursive least squares estimator. The associate editor coordinating the review of this manuscript and approving it for publication was Zheng Chen .

This paper analyzes control strategies for induction motors in railway applications. The paper will focus on drives operating with a low switching to fundamental frequency ratio and in the overmodulation region or six-step operation, as these are the most challenging cases. Modulation methods, efficient modes of operation of the drive and the implications for its dynamic performance, and machine design will also be discussed. Extensive simulation results, as well as experimental results, obtained from a railway traction drive, are provided.

A new integrated mathematical model for the simulation of an offshore wind system having a rectifier input voltage malfunction at one phase is presented in this paper. The mathematical model considers an offshore variable-speed wind turbine on a floating platform, equipped with a permanent magnet synchronous generator using full-power three-level converter to inject energy into the electric network, through a high voltage direct current transmission submarine cable. The model for the drive train is a discrete three mass, incorporating the dynamic of the moving surface. A case study is presented to access conclusion about the malfunction.

This paper is on variable-speed wind turbines with permanent magnet synchronous generator. Three different drive train mass models and three different topologies for the power-electronic converters are considered. The three different topologies considered are respectively a matrix, a two-level and a multilevel converter. A novel control strategy, based on fractional-order controllers, is proposed for the wind turbines. The influence of a converter control malfunction on the harmonic current emissions is studied. The performance of disturbance attenuation and system robustness is ascertained. Simulation results are presented, and conclusions are duly drawn.

A wind energy conversion system run by a variable speed wind turbine having pitch mechanism and two mass direct driven permanent magnet synchronous generator is implemented in this paper. Multilevel inverter is an emerging power technology recently for high-medium application. Out of different topologies, cascaded H bridge multilevel inverter is implemented with WECS as it requires fewer components as compared to other multilevel inverter. One of the major limitations is the use of separate dc source for each H Bridge in cascaded multilevel inverter which can be overcome by inserting isolation transformer. For generation of seven level controlled output voltages, a phasemulti-carrier pulse width modulation is used. The proposed WECS having seven-level inverter having isolation transformers is simulated in MATLAB/SIMULINK. The simulated waveform of the output obtained from PMSG, DC link voltage, Pitch angle and three phase CHB MLI voltages are shown.

Induction motors are widely used in industrial power plants due to their robustness, reliability and high performance under variable operating conditions in the electrical power system. Modern industrial progress is dependent on these ruggedly constructed induction motors. Almost every sophisticated process of the industry is based on induction motors. Most of these motors are controlled by means of inverters that change the line frequency. The change in parameters of inverter makes it possible to control the motor according to the design requirements. The reliability of inverter based motor control is an important issue for industrial applications and therefore, it becomes very vital for design engineers to have comprehensive analysis of the inverter fed induction machine. This paper investigates one of the faults that may occur on the DC link of an inverter fed induction motor. The effect of the capacitor short circuit is presented in this paper. It also deals with the effects of short circuited capacitor on freewheeling diode. DC link capacitors are well designed and even the probability of capacitor failure is high, it is always a rare case if they puncture, however this analysis will add to the reliability of the induction machine under variable operating condition.

The cascaded H-bridge converter is one of the viable options for next-generation large-scale photovoltaic power conversion. Owing to the increased number of components involved, converter reliability and fault tolerant control are important issues. The cascaded H-bridge converter must also manage unequal power generation among the bridges, which is inherent in photovoltaic applications because of unequal solar irradiance and/or module temperatures. The paper proposes a fault tolerant strategy, which maintains balanced three-phase grid currents during faults with unequal power generation in the healthy H-bridges. The effectiveness of the presented fault tolerant control is verified using results obtained from a 430 V, 10 kW laboratory prototype. Index Terms-AC-DC power converters, cascaded H-bridge converter, multilevel converter, photovoltaics, fault-tolerant operation. NOMENCLATURE V ga , V gb , V gc Three-phase grid voltage vectors. V g Grid voltage (line-to-line) (rms). V a , V b , V c Three-phase converter output voltage vectors. v a , v b , v c Three-phase converter output voltages (instantaneous values). v + a , v + b , v + c Positive sequence component of threephase converter output voltages (instantaneous values). I ga , I gb , I gc Three-phase grid current vectors. i ga , i gb , i gc Three-phase grid currents (instantaneous values). I g Grid current (rms). V 0 Fundamental frequency zero sequence vector. v 0 Fundamental frequency zero sequence component (instantaneous value). V 0 Fundamental frequency zero sequence component (rms).

The islanded mode of operation of an electric power system (EPS) that has generation capabilities provided by conventional thermal power plants, by a pumped-storage power station, or from an interlink with a neighboring electric power system through an HVDC BtB converter is addressed in this paper. The risk for electrical power systems to fall into an islanded mode has recently grown, as it is caused not just by technical reasons but by a geopolitical situation as well. The current strains demand the close consideration of problems related to EPS operation in an islanded mode. This paper considers several. The research covers the following issues. The response of the islanded system to a sudden and spasmodic load change is analyzed in cases when the system deals with the disturbance with internal resources alone and with the help of an HVDC BtB converter’s frequency control functionality. Analysis of the impact of the settings of the HVDC BtB converter on the system’s response to di...

The problems of increasing electricity demand by the unabated population and economy growth can be solved by employing sustainable distributed generation technologies. Convectional primary energy sources such as coal, liquid hydrocarbons’ and natural gasses create environmental degradation and energy security problems. Even though the cost of solar energy is zero, the same cannot be said of a solar energy system. The system cost especially the initial capital investment has been hindering the rapid deployment of solar energy systems. One way of reducing the system cost of a solar energy system is to look into the constituent components and see where cost can be reduced without compromising the system efficiency and human safety. Eliminating the isolation transformer reduces the cost and increases the system overall efficiency. However, the galvanic connection between the PV array and the utility grid creates a safety problem for people and system equipment. We present a simplified m...

In this paper, a comparison between three double-stage grid-connection systems in central inverter configuration is presented. This configuration can be used to obtain a wide power range and is suitable for the connection to three-phase grids. In this case, the photovoltaic (PV) panels are connected to the inverter via a dc-dc converter to ensure an optimal dc voltage level. The focus is on the characteristics and properties of the used converter's structures. All the design steps of a grid connection system are also presented. Both two-level (2L) and three-level (3L) voltage structures are implemented. At the end of the paper, a detailed analysis highlights the advantages and disadvantages of the three photovoltaic systems connected to the grid.

Nowadays there is need of alternate energy sources due to the paucity of non-renewable energy sources. Because of which they're moving towards renewable energy sources. This paper presents the efficient use of solar power by operating Photovoltaic (PV) panels at the utmost point (MPP) for powering a induction motor drive. The proposed system implemented the appliance to offer power from solar power to induction motor drive by converting the DC electrical power generated from a PV panel to AC power using the resonant inverter. When the switches are turned on and off, a standard inverter generates switching loss due to the hard switching. Thus, the inverter loss is increased. Proposed system contains auxiliary circuit. The converter stage switches perform soft switching due to the resonant circuit. Hence, the system reduces switching loss and voltage stress.

P This paper presents the simulation and analysis of Photovoltaic assisted three phase five level Diode Clamped multilevel inverter fed induction motor drive. Photovoltaic technology is one of the most promising for distributed low power generation. Its ability to produce power by directly converting solar energy has led to tremendous surge in its demand. The Photovoltaic output DC is fed to the boost converter to step up the voltage. The use of multilevel inverters have become popular in recent years for high power applications and an effective and practical solution for increasing power and reducing harmonics of AC waveforms. So, here a five level multilevel inverter is used for generating AC voltage from five levels of DC voltages and enhance the performance of the system. The proposed system is used to reduce the amplitudes of all harmonics at the output of the inverter. The power quality improves by reducing the harmonics level. The simulation results for the proposed system ar...

DC-DC converters are essential in the interconnection of photovoltaic (PV) systems and systems that operate at different voltages, frequencies, and powers, such as smart grids. Due to the energy transition, and therefore the need for high efficiency in PV systems and smart grids, there is a great challenge to develop DC-DC converters with the highest possible efficiency. Therefore, in this paper an isolated DC-DC converter with high efficiency and easy implementation is developed, in comparison with other similar structures. In isolated converters it is necessary to address the analysis and design of the transformer. Poor performance of this element can contribute to high losses and low efficiency of the converter topology. This study proposes an isolated DC-DC converter (FBDC) that operates at different levels of harmonic content in its supply. The design is subjected to two levels (2L) and three levels (3L), which affects the THD value. The proposed converter model is simulated in...

International audienceThis paper focuses in the optimization of the efficiency of photovoltaic power conversion chain; we present the optimization of the efficiency of photovoltaic power conversion chain. In this way, we present a new alternative for improving both the performance of photovoltaic (PV) systems and the efficiency of the energy conversion by using different configuration of power converters. Different type's improvements have been proposed of architecture in order to choose the correct PV architecture for each PV installation on the efficiency improvement in all power conversion level stages between PV cells and loads. In this context, this work presents the study and adaptive simulation of photovoltaic systems with micro inverters configurations for applications of renewable energy. We performed comparative between a central and distribution connection of converter via an adaptation floor with Maximum Power Point Tracker (MPPT) control. For thisreason, it is impor...

The energy conversion systems especially dedicated for the conversion of electrical power from solar generators into a grid are analysed. Lot of systems are basically developed on boosters or inverters including electronic switches such as MOS or bipolar transistors. The limits of efficiency are quickly reached when high output voltages and high input currents are needed. After presentation of some usual classical systems, pointing out their advantages and drawbacks, we propose an original system based on a standard push-pull converter associated with a dynamic modulation control. The main advantage of this combination is the possibility to control the delivered electric power in a wide range between very low to high levels within the same basic architecture.

In this paper a five-level Multi-Clamped Multilevel Converter (5L-MLC 2) topology is analyzed based on a typical grid integration application for renewable energy system. The loss and thermal distribution of the power devices in different switching legs are investigated and illustrated under rated condition. Afterwards, a loss and efficiency evaluation method is proposed and applied which take into account various injected reactive power ranges regulated by the grid codes. It is concluded that the loss and thermal distribution of 5L-MLC 2 multilevel topology is unequal between the clamping switching legs and the main switching legs, it also shows a good and consistent efficiency characteristic under different output power ranges when complying with the grid codes.

Tremendous promotion and growth of Large-Scale Solar Photovoltaic (LSSPV) Power Plant in Malaysia increase the reliability and potentiality of the system in having efficient monitoring, operation and maintenance for the plants. Through the Ministry of Energy, Science and Technology, the government aims to increase the renewable energy in its generation mix in 2025 by 20% and intends to reduce its greenhouse gas (GHG) emission intensity per unit of gross domestic product (GDP) to 45% by 2030. This was followed by the Energy Commission (EC) announcement of 500 MW LSSPV power plants in Malaysia, slated for commercial operation in 2021. Thus, proper monitoring and respectable power generation are crucial to optimising LSSPV for grid interconnection. This paper presents the assessment of string inverters configuration and analysis models to recommend an optimised configuration for maximum harvested power generation in the LSSPV power plant in Malaysia. An analysis of string invert config...

This paper proposes a modular, medium voltage, highpower converter topology for the large permanent magnet wind generator system, eliminating the gridside step-up transformer, which is desirable for both onshore and offshore wind turbines. The power conversion systems for large wind turbines are facing a great challenge as today’s wind turbine power outputs approach 5 MW and above. The conventional low voltage power conversion system will suffer from a high transmission current, which significantly increases losses and cost of the cables as well as voltage drop. The converter modules are cascaded to achieve medium voltage output. Each converter module is fed by a pair of generator coils with 90 phase shift to get the stable dc-link power. At the gridside, H-bridge inverters are connected in series to generate multilevel medium voltage output and the voltageoriented vector control scheme is adopted to regulate the converter active and reactive power transferred to the grid. The power...

Solar energy is prevalent in many applications, therefore, the reliability of solar energy systems has become an important topic for research communities and industry. High reliability and fault-tolerant capability are particularly vital for the solar energy systems that are mission-critical and/or inaccessible to affordable maintenance. In order to enhance the reliability of a grid-tied PV system, a fault-tolerant Photovoltaic (PV) inverter, termed Integrated Fault-Tolerant PV Inverter (IFTPVI), is proposed in this paper. The IFTPVI is based on the Highly Efficient and Reliable Inverter Concept (HERIC) and H5 inverters that are both popular and commercialized transformerless inverters in grid-tied PV applications. The IFTPVI can tolerate both open-circuit (OC) and short-circuit (SC) faults while maintaining the same voltage and current levels. The system description, reliability analysis, simulation in Matlab/Simulink 2018, and experimental results are provided to verify the feasib...

The use of photovoltaic panels for is becoming popular all over the world for producing electricity for grid connection via using transformer. Grid-connection of solar panel without using a transformer is being reported nowadays. Photovoltaic (PV) grid connected converter without transformer is associated with the problem of non-existent galvanic isolation as a result of transformer absence. The most prominent one issue is the development of common mode voltage leading to commonvoltage leakage current. Hence the grid connected PV module of transformer-less panel, though improve power efficiency, suffers from the loss of power due to leakage current. The leakage current in between grid connection and PV panel develops through paths made up by the parasitic capacitances. Moreover, some topologies propose for omitting this abysmal common mode leakage current. This paper shows how low-pass filters of different order affect the wave-shape of the resulting output voltage in the presence of common mode leakage current in transformer-less topologies.

In this paper, the dynamic modeling of the studied micro grid (MG) is presented for steady state and transient operation conditions. Moreover, control strategies to obtain the maximum converted power and stabilize the voltage under different operating conditions are derived. The integrated system under study has four key subsystems to supply the required electric loads. The first and second subsystems include the layout of the studied MG and the renewable generation sources from Wind turbine and PV array. The third represents the boost converter between the PV and the DC collection bus as well as the interfaced inverter to the point of common coupling (PCC) with the MG. The fourth subsystem comprises mainly the required PI controllers to regulate the modulation index of the inverter and the duty cycle of the boost converter for PV maximum in addition of regulating the boost inverter DC link voltage. The proportional and integral parameters of these controllers are tuned off-line to enhance the grid performance. The integrated system and the associated subsystems are fully validated for efficient operation under normal or fault conditions using the Matlab/Simulink/Sim-Power software.

A new integrated mathematical model for the simulation of an offshore wind system having a rectifier input voltage malfunction at one phase is presented in this paper. The mathematical model considers an offshore variable-speed wind turbine on a floating platform, equipped with a permanent magnet synchronous generator using full-power three-level converter to inject energy into the electric network, through a high voltage direct current transmission submarine cable. The model for the drive train is a discrete three mass, incorporating the dynamic of the moving surface. A case study is presented to access conclusion about the malfunction.

The whole world is focusing on the utilization of renewable energy sources in order to mitigate the world power crisis. Power electronics is being used in a large scale for the renewable energy conversion in a more efficient manner. It has a great impact on controlling as well as interfacing the renewable system with both the grid and standalone applications. Hence more and more emphasis is given on design and control of power converters. In this paper different renewable energy systems (wind, solar) with different aspects of their power conversion have been discussed. Some basic principles of their operations with their recent technology advancements are reviewed. It is the reality that power electronics plays a vital part on interfacing and hence increasing the overall performance. Keywords—Power electronics; Renewable energy systems; Wind energy conversion system; Photo voltaic system.