Phase Grid Research Articles

Development and validation of enhanced fuzzy logic controller and boost converter topologies for a single phase grid system

Introduction. Solar photovoltaic system is one of the most essential and demanding renewable energy source in the current days, due to the benefits of high efficiency, reduced cost, no pollution, and environment friendly characteristics. Here, the maximum power point tracking controller has been implemented for obtaining an extreme power from the photovoltaic array. For this purpose, there are different controller and converter strategies have been deployed in the conventional works. It includes perturb and observation, incremental conductance, fuzzy logic systems, and hill climbing, and these techniques intend to extract the high amount of power from the solar systems under different climatic conditions. Still, it limits with the issues like increased design complexity, high cost consumption, high harmonics, and increased time consumption. The goal of this work is to deploy an improved controlling and converter topologies to regulate the output voltage and power fed to the single phase grid systems. The novelty of the work aims to develop an enhanced fuzzy logic controller based maximum power point tracking mechanism with the boost DC-DC converter topology for a single phase grid tied photovoltaic systems. Practical value. Also, the higher order harmonics suppression and unbalanced current elimination are handled by the use of LCL filtering technique, which efficiently reduces the harmonics in the output of inverter voltage and current. Moreover, it helps to obtain the reduced total harmonics distortion value with improved accuracy and efficiency. Results. There are different performance indicators have been evaluated for validating the proposed enhanced fuzzy logic controller–maximum power point tracking controlling technique. Moreover, the obtained results are compared with some of the conventional controlling algorithms for proving the betterment of the proposed work.

Three Phase Grid Connected Inverter for Solar Photovoltaic Systems

Abstract: The main aim is to convert the Solar PV DC voltage into AC voltage by using 3 phase inverter and getting sinusoidal AC output voltage. To convert solar PV which is in DC needs to be converted into AC by using the devices like 3 phase inverter and boost converter. The solar PV is a variable DC that is to be converted into pure DC for which will convert variable DC to pure DC. The MPPT is designed and is applied to boost converter which increases the solar PV’s efficiency. Then the output of boost converter which is DC voltage is given to 3 phase inverter. The 3 phase inverter which is connected to output of boost converter will convert the DC voltage into AC and we get sinusoidal AC. A three-phase grid-connected inverter designed for a photovoltaic power plant that features a maximum power point tracking (MPPT) scheme based on fuzzy logic. The whole system simulate in MATLAB. This fuzzy MPPT will shows accurate and fast response, and is integrated in the inverter.

Comparative Study of DC/AC Inverter Control Techniques for Three Phase Grid Connected PV System

The goal of this project is to develop and analyze a three-phase grid-connected photovoltaic (PV) system with a 250KW power capacity with expandable property. The PI, Slide, and MPC methodologies are used to test three distinct inverter current control techniques. The dynamic performances of the three inverter control techniques are virtually comparable under grid connected working conditions, although the dynamic performances of the traditional PI control technique are slightly better and smoother than the other two inverter control techniques. The unity power factor criterion was reached by all techniques. The output power levels obtained using the sliding mode inverter control method are higher than those obtained using the PI and MPC methods. MPC's DC link voltage readings are also consistent and match the intended voltage levels.

A fast voltage sag detection method based on second order generalized integrator and delay transform method

Voltage sag is an important problem that causes power quality degradation, and the premise of solving the problem of voltage sag is to detect the depth of voltage sag accurately and quickly. Based on the past research on voltage sag detection, this paper proposes a voltage sag detection method that combines second order generalized integrator and delay transform method. Use the second order generalized integrator as the phase-locked loop and filter to extract the grid voltage phase angle and grid voltage fundamental wave, and then construct the quadrature component of the grid voltage fundamental wave by delaying a small angle. Square and square root calculation to quickly obtain voltage sag information. At the same time, the voltage sag information is used as the control signal of the second order generalized integrator to solve the problem of long response time of the second order generalized integrator. In this way, the interference of harmonics, zero-sequence and negative-sequence voltages on sag detection is excluded, and the rapidity of sag detection is ensured. Simulation and experiments show that the method can accurately and quickly determine the voltage sag depth.

An Efficient Control Scheme Based on PLL Integrated PI Controller for Grid-connected Solar Photovoltaic Systems

The market for solar energy is growing these days, thanks to recent developments in Photovoltaic (PV) systems. The integration of solar energy to the grid is required for its optimum utilization. A novel control of a single stage 3 phase grid connected solar inverter is presented in this paper. A PV array, Voltage Source Inverter (VSI) for converting dc to ac, and a filter that connects it to the grid are the major components of the proposed system. The inverter output is regulated with respect to the grid using Synchronous Reference Frame (SRF) control. A 3-phase Phase Locked Loop (PLL) is used to lock the grid frequency and phase in relation to inverter output voltage. The Perturb and Observe (P&O) algorithm is used to obtain the reference voltage corresponding to the maximum PV power. To remove the high frequency harmonics, the inverter output is combined with an LCL filter. The dynamic performance of the proposed system under the number of stochastic environmental conditions are validated using MATLAB Simulink platform.
 HIGHLIGHTS
 
 The proposed PLL integrated PI controller provided high robustness under stochastic environmental conditions
 Enhanced system dynamic performance and accurate MPP tracking
 The inverter output is free from the high frequency harmonics
 Improved control performance
 
 GRAPHICAL ABSTRACT

Modelling and Analysis of Three Phase Grid Photo Voltic System for Electric Vehicle

Abstract: Renewable energy systems area unit seemingly to become wide spread within the future thanks to adverse environmental impacts and step-up in energy prices connected with the exercise of established energy sources. Solar and grid energy resources area unit various to every different which can have the particular potential to satisfy the load quandary to a point. However, such solutions any time researched severally aren't entirely trustworthy thanks to their impact of unstable nature. During this perspective, autonomous electrical phenomenon and grid hybrid energy systems are found to be a lot of economically viable various to meet the energy demands of diverse isolated shoppers worldwide. Conservation of energy is extremely traditional these days however management of energy is extremely essential issue to figure on the idea of change to energy generation devices for continuous provide of dc storage conjointly demand of electricity is increasing day by day however accessible wattage plants aren't ready to provide electricity as per the strain wants. The main objective of the project is to supply a framework for promotion of enormous grid connected grid - solar PV hybrid system for optimum and economical utilization of transmission infrastructure and land. Project conjointly aims to encourage new technologies, ways and way-outs involving military operation of grid and solar PV plants. Battery storage could also be other to the hybrid project to cut back the variability of output power from grid solar hybrid plant, for providing higher energy output for a given capability at delivery purpose, by putting in further capability of grid and solar energy in an exceedingly grid solar hybrid plant and making certain handiness of firm power for a specific amount. Keywords: Electric vehicle, solar power, vehicle-to-grid, management of power.

Nonlinear PID (N-PID) Controller for SSSP Grid Connected Inverter Control of Photovoltaic Systems

In this work, a Nonlinear Proportional Integral Derivative (N-PID) controller based on Popov's stability criterion is applied for retaining the power quality of single stage single phase grid connected photovoltaic systems. Popov's stability criterion based nonlinear gain is added with conventional PID controller design which is termed as N-PID. Here, Nonlinear gain is designed with the approach of the controller to provide a nonlinear relationship with the error for the accuracy in reference tracking as conventional PID controller shows a linear relationship with the error. Thus, the N-PID controller joins the benefits of conventional PID controller and also reduces the complexity of tuning of PID gains as tuning of PID gains is the most challenging process of the conventional PID controller to achieve the accuracy on set point tracking. N-PID is designed in such a way to control the duty cycle of DC-AC converter for obtaining the maximum power without any harmonics, also for achieving unity power factor and achieving the efficiency with 96%-99% of the system. The proposed topology with N-PID controller ensures fast tracking of maximum power point, reducing harmonics considerably and improving the efficiency further with the wide investigation of error over the responses.

Design of L, LCL and LLCL Type Filter for Single Phase Grid Connected Inverters

Bu çalışmada, tek fazlı şebeke bağlantılı evirici için L, LCL ve LLCL tipi filtre tasarımları yapılarak filtre tipleri birbirleri ile kıyaslanmıştır. Tasarım için şebeke akımının toplam harmonik bozulma (THD) değeri %5’in altında oluşacak şekilde filtre parametre değerleri hesaplanmıştır. Filtre parametre değerleri belirlendikten sonra PSIM programında simülasyon çalışmaları gerçekleştirilmiştir. Çalışmada aktif güç kontrolü, oransal-rezonans (PR) akım kontrolü ve gelişmiş faz kilitlemeli döngü (PLL) kontrolü için gerekli olan kodlar C bloğu içerisine yazılmıştır. Simülasyon sonuçlarına göre 1 kW güç, 220 V AC şebekeye aktarılırken en yüksek THD değeri %4.92 olarak L tipi filtrede elde edilirken, en düşük THD değeri %0.99 olarak LLCL filtre tipinde oluşmuştur. Yapılan filtre tasarımına göre endüktans değeri en yüksek olan filtre tipi de L filtredir. LCL ve LLCL filtre tiplerinde THD değerleri düşük çıkmasına rağmen uygun parametre değerlerinin seçilmesinin önemli olduğu görülmüştür.

A Reactive Power Compensated Control Scheme for Solar-Assisted EV Fast-Charging Applications

The main objective of this work is to develop an efficient reactive power compensated control technique for a fast-charging scheme for electric vehicle(s) (i.e., level-3 charging). The developed charging technique has the four-quadrant power flow operation with the simultaneous assurance of the compensated reactive power control. The developed charging infrastructure scheme involves a solar panel and 3-phase grid to charge the E-mobility. A DC-DC boost converter is used to achieve maximum power tracking (MPPT) of a solar PV array, and a 3-phase grid-tied bidirectional voltage source converter (VSC) is utilized to provide the bulk of power to charge the EV. The 3-phase VSC has multiple functionalities including grid side power quality (PQ) improvement with reactive power compensation, seamless flow of power from the grid to EV, and solar to grid or battery to grid (V2G) operation. This scheme also facilitates tariffs earned by discharging solar energy to the grid with additional benefits of reactive power compensation. An arrangement is also made to tackle grid failure conditions during battery discharging mode by connecting a load for ancillary purposes. The effectiveness of this charging scheme is first examined in MATLAB/Simulink environment and then validated on developed hardware.

Single phase grid interconnected high gain boost converter with soft switching capability

<div align="left"><span>The grid interconnected application systems require high voltage levels which leads to an efficiency reduction. To overcome this, a new high gain boost converter in association with buffer capacitor, passive clamp recovery circuit to restore leakage energy in coupled inductor is presented. The magnetic field of the linked inductor stores the energy obtained from the supply. The energy is transmitted to the connected load for consumption in further operating modes. A passive clamp network recovers the energy that is stored in the leakage inductance, enhances the gain of voltage, and improves overall system efficiency. The essential feature of this converter is that, high duty ratios are not required to achieve higher voltage gain, hence the reverse recovery problem of the diode is prevented. Moreover, a passive clamp network decreases the voltage stress of the switch, thus a minimum rating switch is used, as a result, the system's total efficiency improves. This converter output is fed as input to a single-phase full-bridge inverter and also synchronized to a single-phase grid. The performance and powers injected are analyzed by connecting a resistive load. </span></div>

Fuzzy logic controller for maximum power point tracking and voltage stability control in distributed generation

Distributed Generation Resources are gaining popularity in power systems because of their closeness to the consumer loads, their capability of producing clean power and their ability to provide reactive power compensation. In this paper renewable energy resource which is Photovoltaic Power Generator has been used as a Distributed Energy Resource. For achieving Maximum Power Point Tracking (MPPT) from the Solar Panels under certain insolation a fuzzy logic controller has been utilized. Similarly for reactive power compensation of the loads in the three phase grid through DC-AC converter, Fuzzy Logic controller has been used for controlling the gate pulses to the three phase inverter. Matlab Simulation has been implemented to study the waveforms of the three phase voltages and currents at the point of common coupling ie interface between the three phase inverter and grid.

Phase coding of spatial representations in the human entorhinal cortex.

The grid-like activity pattern of cells in the mammalian entorhinal cortex provides an internal reference frame for allocentric self-localization. The same neurons maintain robust phase couplings with local field oscillations. We found that neurons of the human entorhinal cortex display consistent spatial and temporal phase locking between spikes and slow gamma band local field potentials (LFPs) during virtual navigation. The phase locking maintained an environment-specific map over time. The phase tuning of spikes to the slow gamma band LFP revealed spatially periodic phase grids with environment-dependent scaling and consistent alignment with the environment. Using a Bayesian decoding model, we could predict the avatar’s position with near perfect accuracy and, to a lesser extent, that of heading direction as well. These results imply that the phase of spikes relative to spatially modulated gamma oscillations encode allocentric spatial positions. We posit that a joint spatiotemporal phase code can implement the combined neural representation of space and time in the human entorhinal cortex.

A New Control Strategy for Three Phase Grid Connected PV System Under Severe Partial Shading Conditions

A New Control Strategy for Three Phase Grid Connected PV System Under Severe Partial Shading Conditions

A Noval Method of Levenberg-Marquardt Based Solar Mppt for Single Phase Grid Connected System

A Noval Method of Levenberg-Marquardt Based Solar Mppt for Single Phase Grid Connected System

High efficient and high gain boost converter with soft switching capability connected to grid using dq axis current control

Renewable sources like solar PV arrays are generally operated at low voltages due to safety issues. For applications such as grid connected systems, it requires boosting to high voltage which leads to reduction in efficiency. To solve this, a new high gain and efficient boost converter which is a combination of buffer capacitor, passive clamp recovery circuit to restore leakage energy in coupled inductor is presented. The magnetic field of the linked inductor stores the energy obtained from the supply. A passive clamp network recovers the energy that is stored in the leakage inductance, enhances the gain of voltage and improves overall system efficiency. High duty ratios are not essential to achieve higher voltage gain, hence the reverse recovery problem of diode is prevented. Moreover, passive clamp network decreases the voltage stress of switch, thus a minimum rating switch be used, as a result, the system's total efficiency improves. This converter output is fed as input to a single phase full bridge inverter and also synchronized to a single phase grid by using d-q axis current controller. The performance and powers injected are analyzed by connecting a resistive load.

PI Optimized Cuckoo Search Algorithm for Single Phase Grid Tied PV Inverter with SEPIC Converter

A new approach for single phase grid interconnected PV module with SEPIC converter is introduced in this paper. As the outcome of PV is low voltage DC, a suitable converter is needed to boost the voltage. Hence SEPIC converter is used as it has high voltage gain with same polarity in the input as well as output side. A closed loop control is executed with a PI controller tuned with Cuckoo search (CS) algorithm. As the traditional tuning of PI controller results in peak overshoot problems, Cuckoo search (CS) based Optimization is utilized as it is simple with has a smaller number of tuning parameters. This output is being fed to the grid through a single phase VSI and the grid synchronization is accomplished by PI controller by analogizing the actual and reference values of power. Thus, the proposed control strategy is verified through MATLAB and it is observed that the source current THD is minimized, which satisfies the IEEE standard.

Impact of Mission Profile on Reliability of Grid-Connected Photovoltaic Inverter

In recent decades intense demand for energy increases the utilization of Photovoltaic (PV) energy as an alternative to fossil fuels. Today’s PV energy shares a significant electricity demand with the advancements in power electronic technologies. Nevertheless, reliability performance of PV system is a major concern. Environmental conditions like mission profile (Solar Irradiance; Ambient Temperature), installation location impacts the performance of PV system. Researchers reported PV inverter as the critical component of PV system. Furthermore, reliability assessment of PV inverter considering environmental conditions is needed for the reliable operation. Therefore, the aim of this paper is evaluating the impact of mission profile on reliability (lifetime) of PV. To accomplish this, a 3-kW single phase grid connected PV system with full bridge PV inverter is considered as test case and modelled in PLECS. A 600V/30A IGBT from leading manufacturer is considered as power electronic switch in PV inverter. Top ten countries of PV market are identified and selected as installation locations, real time mission profile for one year at each installation location is considered. With this mission profile reliability assessment of PV inverter is carried out on test case. The results reveal that mission profile have considerable impact on reliability performance of PV inverter.

Robust [formula omitted] fuzzy adaptive controller for three-phase grid-connected photovoltaic system

A robust L1 fuzzy adaptive controller is proposed in this paper for a grid-connected photovoltaic (PV) system. The latter contains a solar PV array connected to a three phase grid through a DC/AC inverter. The designed controller consists of a control law, an adaptive mechanism and a predictor. A fuzzy system is incorporated in the controller structure to achieve a good approximation of unknown nonlinear dynamics and uncertainties. Unlike conventional adaptive control strategies, the proposed control method permits fast adaptation without compromising robustness. Therefore, it can significantly improve the control performance of this type of energy conversion systems characterized by fast dynamics. Furthermore, the presented control scheme ensures the stability of the closed-loop system with bounded transient and tracking performance.

Performance enhancement of a high-speed railway supply system with multi module converter: a laboratory prototype model for Indian railways

The present Indian traction supply system’s complications (neutral sections of the catenary line and issues of power quality) restrict the growth of railway transportation, particularly high-speed rail networks that are fast growing globally. The neutral sections (NS) results in loss of speed, momentum and mechanical failures that are all threatening the fast and stable operation of trains and systems. In the meantime, issues with the power quality such as the negative sequence currents (NSC), the reactive power and harmonics may create problems on the three phase grid side that cannot be overlooked. To address these two issues concurrently, a new traction power supply system is designed in this paper. The proposal will also analyses the theory of operation, build the mathematical model and develop the control system for back to back converters. Small scale prototype is also made for validation of simulation results. The results shows that it can fulfil the practical requirements. The experimental results shows that the overall system is practically more appropriate for the high speed railway.

Grid interfaced solar-wind hybrid power generating systems using fuzzy-based TOGI control technique for power quality improvement

This paper bestows 3-phase grid interfaced solar-wind hybrid renewable energy system (RES), feeding three-phase loads. The proposed system includes solar photovoltaic, permanent magnet based synchronous generator (PMSG), DC-DC converter, maximum power point tracker (MPPT) based on incremental conductance, three phases IGBT based voltage source converter (VSC), with a third order generalized integrator (TOGI) control technique. This control technique bestows multifunctional capabilities as harmonic mitigations, load balancing, and reactive power compensation. A fundamental component of load current is extracted by TOGI based controller, and further it is utilized to provide switching pulses to VSC for power quality enrichment. The fuzzy logic-based controller is used for loss computation of VSC as well as for maintaining DC link voltage. Moreover, fuzzy logic provides better dynamic performance compared to conventional PI controller. The results are presented in many aspects for linear and nonlinear loads such as, intermittent nature of solar and wind as well as disturbances in the system. A comparative analysis between proposed TOGI based controller and conventional control algorithm has been presented. Test results are performed by using MATLAB/ Simulink environment and demonstrate, AC-grid current is maintained within the IEEE-519 standard.