DG System Research Articles

Adaptive Protection Scheme for FREEDM Microgrid Based on Convolutional Neural Network and Gorilla Troops Optimization Technique

Microgrids (MGs) suffer from unpredictable faults on the feeders for various random reasons. These faults could obstruct the stability of the MG operation and damage the components. Moreover, many uncertainties elements affect the MG’s response to faults, such as faults’ types and locations and resistances, MG operation modes, DG penetration levels, load variations, and system topologies. Therefore, fault detection, classification, and location are vital for the MGs as they provide rapid restoration and protect the components. This paper proposes an adaptive protection (AP) scheme for the future renewable electric energy delivery and management (FREEDM) system. The proposed scheme is based on the convolution neural network (CNN), in which the measured current and voltage at buses are processed in multidimensional arrays for the images’ identification and classification. The gorilla troops optimization (GTO) technique has been used to improve the CNN by acquiring the optimal architecture and hyperparameters of the proposed CNN. The proposed protection scheme can detect the system fault, classify the fault type, and determine the fault location using three proposed CNN-GTO protection scheme models. A communication channel has been performed to transfer the data, information, and tripping signals between the different devices in the FREEDM system. The proposed method is tested using a hypothetical FREEDM microgrid system under different fault conditions. The results show that the proposed CNN-GTO models can detect, classify, and location feeder faults in the FREEDM system with high accuracy. A comparison with the existing schemes such as Support vector machine, Fuzzy logic, conventional CNN, and wavelet-based CNN is performed. The optimized CNN-based GTO models can achieve an overall accuracy for fault detection, classification, and location of 99.37, 99, and 98.2%, respectively.

Design and Analysis of Enhanced Boost Active Switch Controlled Based ZSI for Photovoltaic DG System

Design and Analysis of Enhanced Boost Active Switch Controlled Based ZSI for Photovoltaic DG System

Modelling and Analysis of Microcontroller Based MPPT Method Using FPGA

Now days, the renewable energy sources (RES) are the most accomplished system for power generation. In this paper, focus on FPGA based digital controller for the grid connected DG system. The study and performance analysis of grid-connected PV system as follows to improve the efficiency of the grid system and to extract the maximum power. This work is designed & development of FPGA. The DC power and battery capture on the DC bus system we have maintained the unity power factor and harmonics current in the DG system. The bi-directional battery systems also provide quick response & the performance under the variable DC voltage. Then, to develop the effectiveness control strategy is to manage the power flow equally AC & DC sides. This system simulated in MTTLAB Tools and FPGA System.

Design and analysis of optimal passive filters for increasing the harmonic-constrained hosting capacity of inverter-based DG systems in non-sinusoidal grids

Design and analysis of optimal passive filters for increasing the harmonic-constrained hosting capacity of inverter-based DG systems in non-sinusoidal grids

A Novel Islanding Detection Technique Based on Piezoelectric Sensors for Grid-Integrated DG Systems

This paper presents the novel islanding detection technique that depends on the piezoelectric sensors for distributed generation sources (DGs) in the grid-integrated operation mode. The islanding detection method employs a piezoelectric sensor for the detection of the frequency variations during grid disruptions. The designed diaphragm-based sensor has a natural frequency as that of the fundamental frequency of the system frequency signal. Any further deviations from the natural frequency due to the disturbances will be sensed by the sensor and a control signal is being sent to the associated circuit breaker for suitable action. The sensor structure is modeled using the finite element method and implemented in the Phase-Locked Loop (PLL) of the grid-integrated DGs. The proposed circular diaphragm-based sensor structure will have the bandwidth in the range of natural frequency with the tolerance rate of ±1% and uses the input signal received from the PLL controller outer loop. The proposed islanding detection technique’s performance and reliability for grid-integrated DG are validated using the real-time hardware in the loop test-bed platform. The HIL virtual simulated responses show that the method can be proposed effectively for islanding detection in the event of frequency variations in the grid-integrated DG systems.

Impact of renewable energy sources integration with power grid systems through several methodology's

This paper is primarily committed to three primary angles concerning photovoltaic based DG. The fundamental perspective being the reduction of influence changes in daylight based photovoltaic and the Reduction of influence distribution in the framework of the system. According to the unpredictable changes credited to the wide range of sun situated radiations. Further, the sizing related issues and region of an SPV based DG may cause a ton of influence concerns effecting the overall DG system operation and its efficiency. The second region of concern is the method used in the control of the DG and its feasibility to diminish framework influence issues. Another area of concern is network interconnection, through the appropriate introduction of RES into the ordinary grid for supportable and stable activity. This has been managed through an extensive contextual analysis of an operational system.

Implementation of ANN Trained Voltage Control Scheme for Grid Islanded DG System

Distributed generation plays a significant role in power generation, but the standalone system has some limitations like excess power generation and sudden increment in load. Grid interconnected DG system mitigates all this type of problems but some different questions arise in this interconnection. How to synchronize the DG system with the grid? If any change in voltage or frequency they lead to disconnect the grid from DG system. But due to sudden loose of grid supply, the phase angle is changed in filter terminal voltage and leads same change in load voltage because when the grid is connected the load receives power from both DG and grid. In grid-connected system current controller is generally used, to maintain the constant current in load side, so in islanding conditions, the voltage profile will get damage and power factor is also dropped. This paper proposes a strategy of two controllers for both grid-connected and intentional islanding modes. PI controller based constant current regulator for grid-connected mode, while ANN based VC controller for intentional islanding mode. These two controllers are operated according to changes occurred at Point of Common Coupling (PCC).

WITHDRAWN: Comparative analysis on hybrid power system

The analysis of the Multi-area Hybrid Power System's Automated Generation Control (AGC). The hybrid power supply is the combination of thermal generation unit and DG energy. The DG system includes wind turbine generator, Solar photovoltaic system, Diesel engine generator, Aqua electrolyze fuel cell, and battery-electric energy storage. The machine is handled as the secondary controller by a new Fuzzy PID plus FPID-II controller. Novel software technology, such as the salp-swarm algorithm (SSA), based on the multi-objective method, compare these controller gains with three different controller types, such as the pictures, the pictures, the two-degree PID (TDOFPID) controller. In addition, in order to extract the effectiveness of the SSA technology, answers for the different load conditions are compared to other common techniques of swarm intelligence like the Grasshopper Optimization Algorithm (GOA), Ant Lion Optimization (ALO), the Dragonfly Algorithms (DA), or the Particle Swarm Optimization (PSO).

New islanding detection method with adaptively threshold for microgrid

This paper proposes a new passive method with adaptively threshold to address islanding problem of microgrid. The recommended system for islanding analysis is introduced first, and then the rate of change of power factor angle is exploited as the islanding detection index. Under grid-connect state, detection index is higher for non-islanding event. But during islanding operation, detection index approaches zero. Therefore, the introduced detection index can be better distinguish islanding and non-islanding events. Finally, a new passive method considering the voltage/frequency behavior of load is proposed, and the adaptively threshold is given by analyzing the relationship between reactive power and the resonant frequency of load after islanding occurrence. The proposed method is compared with other passive methods against various scenarios of the single and multiple DG systems. Simulation and experiment results demonstrate that the passive method with adaptively threshold has high reliability against islanding and non-islanding events.

Analysis of Islanding Phenomenon in PV Connected System with Protection of Its Effects

Our proposed work to implementation of MATLAB Simulink modelling 2015a version with power generation grid. The main simulation goal to enhancement of islanding detection and protection of DG system. Our result gives better improvement result gives as comparison to previous result. Islanding removal we used Fact power filter like as LC and VSC device. These are reduction of islanding effect and implement of steady state time period.

Dynamic Performance of Fuel Cell DG System with Voltage Quality Improvement Capability (Dept.E)

Dynamic Performance of Fuel Cell DG System with Voltage Quality Improvement Capability (Dept.E)

Power Management Strategy between PV-Wind Hybrid System Using Cuckoo MPPT Techniques

The main theme of this paper is to maintain a power management strategy in grid interfaced hybrid system. Here, the PV and Wind Energy Systems considered hybrid connection systems. Wind and PV systems are more efficient DG systems, as freely available in nature. The DFIG based wind system is designed to generate 16kW and Solar system is designed for rating of 20kW power generation. In addition with battery management system also used for back-up purpose. An MPPT based DC-DC converters are proposed for both PV and Wind systems to improve the reliability and effective power management between the systems under different load conditions. This proposed system is verified in MATLAB simulink environment

An Advanced Signal Decomposition Technique for Islanding Detection in DG System

This article presents a new passive islanding detection method by using an advanced signal decomposition technique, i.e., time-varying filter-based empirical mode decomposition (TVF-EMD). In the TVF-EMD, the adaptively tuned and predefined parameters and variation of the cutoff filter frequencies with respect to time make it more desirable over other decomposition techniques for enhanced resolution-based time-frequency analysis of nonstationary signals. The voltage signal measured at the distributed generation is processed through the TVF-EMD to decompose the signal into various intrinsic mode functions (IMF). The energy of the IMF is further extracted through the Teager energy operator. The computed energy is then used to identify the islanding scenario. In order to assess the performance of the proposed TVF-EMD, a number of simulation studies are performed on two standard test systems under varying islanding (i.e., different power mismatches and load quality factors) and critical nonislanding (i.e., capacitor switching and nonlinear load switching) conditions. The obtained results prove the efficacy of the proposed method.

Advanced Control Methods for Power Converters in DG Systems and Microgrids

In recent years, different advanced control methods have been successfully proposed as alternatives to conventional cascaded linear controllers for power converters in distributed generation systems and microgrids. The prime movers of this research are strong capabilities of advanced controllers to improve the dynamic performance and robustness of power electronic converters in these applications. This article first introduces the key roles and functionalities of voltage source converters in distributed generation systems and microgrids. Then, it describes how these functionalities are traditionally achieved by using linear controllers, and addresses their fundamental dynamic performance limitations. Afterward, the most prominent advanced control methods are overviewed. In this context, the implementation principles, advantages, and disadvantages of prominent model- and data-based advanced control methods are critically discussed and experimentally compared. This article ends with a discussion about promising research directions in the area of advanced control for power electronic converters.

BoSSS: A package for multigrid extended discontinuous Galerkin methods

The software package BoSSS serves the discretization of (steady-state or time-dependent) partial differential equations with discontinuous coefficients and/or time-dependent domains by means of an eXtended Discontinuous Galerkin (XDG, resp. DG) method, aka. cut-cell DG or unfitted DG. This work consists of two major parts: First, the XDG method is introduced and a formal notation is developed, which captures important numerical details such as cell-agglomeration and a multigrid framework. In the second part, iterative solvers for extended DG systems are presented and their performance is evaluated.

Robust Repetitive Control of Power Inverters for Standalone Operation in DG Systems

Standalone operation of an inverted-based distributed generation unit is performed in voltage control mode. In this mode, it is important that the controller provides tracking and rejection of periodic signals. Strategies like Repetitive Control (RC) are well suited in the voltage control of power inverters. However, the robustness of repetitive controllers is importantly affected by the connected loads. The reason is that the load modifies the dynamics of the system where the design of the RC relies on. Having a low bandwidth action can reduce the problem but with the cost of degrading the voltage waveform and transient response. As an alternative, an $H_{\infty }$ design is proposed for the RC of voltage source inverters. In this proposal the load is directly treated as an unstructured uncertainty. With this approach, the design procedure directly maximizes the robust stability margin of the system against load variations/uncertainty. Additionally, the analysis provides some insight about the design of the inverter LC filter. Experimental results show that a remarkable Total Harmonic Distortion and good transient response are obtained for a large variety of loads.

Interconnection of Hybrid Power System to Grid & Enhance Power Quality Features in DG System using Multilevel STATCOM

The distributed generation scheme with integration of renewable energy sources furnishes the feasible solution to acquire the stable power demand in grid-connected system under sudden load interruptions. Over the various compensation devices, the highly recognized multi-purpose Static Compensator is integrated to grid for attaining enhanced power quality features. A co-generation based grid-integrated renewable sources are used but, the output of these sources are maintained un-constant due to presence of variable source. In this paper, a novel current controller was developed to maintain output of co-generation system as constant and achieve the load demand continuously. But, this scheme has two major disadvantages, primary one is current controller prerequisites the traditional PI controller, which is controlled by intelligent based Fuzzy-Logic controller that is adopted. The second is, the regular 3-level voltage-source inverter is used in STATCOM which has square-wave output voltage requires high range of filter units, more common-mode voltage, high dv/dt stress, more switching losses, low efficiency, so on. These issues are counteracted by utilizing multilevel inverter with attractive modulation scheme. The performance evaluation of proposed Multilevel Inverter based STATCOM is verified by traditional PI and proposed Fuzzy-Logic current controller by using MATLAB/SIMULINK tool and results are conferred with comparisons.

Novel circuit to compensate the effect of source open circuit fault in distributed generation system

In this paper a novel compensating circuit, composed of capacitors, one IGBT switch, and a diode bridge is designed and employed within a SOFC distributed generation system connected to a micro-grid. The DG system consists of the FC stack, a Cuk converter, a three phase inverter, the proposed compensating circuit, and Type 2 Fuzzy logic controller to adjust the output voltage to its reference value, to manage the charging of the compensating circuit capacitors during normal operation, and to manage the discharge of the compensating circuit during fault to ensure the continuous power supply to the load during the open circuit fault of the SOFC. A detailed description of the managing controllers and switching sequences is also given. Results proved the validity of the compensating circuit in supplying the load during the absence of the main source, hence preventing serious consequences of shutting down important loads.

PI and Hysteresis Current Controller for Grid-Connected Dynamic State Configuration Model of Solid Oxide Fuel Cell SOFC

As the surrounding problems of the states and the requirement to meet out the increasing energy demand are increasing gradually generation of distributed nature system based various types of clean power systems are being erected increasingly to manage the load side energy requirements and reduce the environmental issues. Fuel cell is the latest technology that can use as DG system and solve the above mention issues. In this research work, a grid-connected dynamic state of solid oxide fuel cell (SOFC) system is represented. The fuel cell stack DC voltage needs to be converted and stepped-up to match the load side grid. So, a DC-AC voltage source converter is utilized to for interfacing the fuel cells with the load side grid, and the transformer is installed for increasing the potential level to match the voltage grid. Two types of control strategies are presented (PI and hysteresis current controller) to control and shape the inverter output voltage, hence provides decoupled real and reactive energy. The entire work is modeled in MATLAB/Simulink.

Design and Simulation of Hybrid DG System Fed Single-Phase Dynamic Voltage Restorer for Smart Grid Application

ABSTRACTThe modern commercial and domestic devices are highly sensitive to the variation in system voltage profile. In proposed work, hybrid DG system fed single-phase dynamic voltage restorer (DVR) is proposed for the purpose of mitigation of voltage sags, swells, and interruptions in single-phase distribution system. In the proposed model, switching control strategy of the DG system enables to solve voltage quality problems with minimum requirement of grid energy. The proposed model, during short or long interruption, is capable of meeting load demand and acts as an uninterrupted power source. Also, proportional integral controlled novel boost inverter results in reduced switching losses in comparison to conventional topology, and thus ensuing in saving of significant amount of energy. For the effectiveness of the proposed model of DVR, the simulation results show that it has recovered the voltage sag up to 0.1 pu and swells up to 1.9 pu of pre-sag voltage.