A novel anti islanding detection method for grid connected fuel cell power generation systems

Renewable energy sources have been developed rapidly all around the world, and one of these green energy sources is hydrogen energy. The fuel cell systems have become prominent in renewable energy sources because of its minimal dimensions and energy conversion method. There have been developed, some applications, especially in domestic and automotive areas, and fuel cell systems are also have been started to use in grid connected systems. Fuel cell systems must have some electrical connection standards while they connected to an electrical grid. One of these electrical conditions and may be the most important one is unplanned islanding condition. Islanding is a very dangerous situation because it can damage to the fuel cell and related electrical systems and also working people have been at risk in islanding situation on the grid. In this study, a novel islanding detection method was introduced for grid connected fuel cell systems. 0.5 kW solid oxide fuel cell (SOFC) system used in developed experimental system and a novel anti islanding detection method was researched by using an effective method. The proposed method was also developed by using Matlab Simulink and its useful tools. The developed islanding detection method is robust, reliable and has a fast response time, according to present methods. The results confirm the suggested conditions, and it can be seen in this method, it can also be adapted easily to the grid connected fuel cell systems.     

Wavelet transform-based fault detection method for hydrogen energy-based distributed generators

Integration of hydrogen energy-based distributed generators (HEBDGs) to the main grid causes some power quality (PQ) problems. The conventional fault detection methods fail to detect some PQ disturbances, thus intelligent methods are proposed in the literature recently. This paper focuses on developing a wavelet transform (WT)-based fault detection method for HEBDG systems to detect PQ disturbances in the low-voltage grid connection. The proposed method uses the discrete WT and Daubechies wavelets of order 4 to detect the voltage swell, voltage sag, voltage interruption and transient disturbances in a HEBDG system. The performance of the WT-based method is also compared with the conventional fault detection methods, and using the time-frequency domain analysis by WT increases the stability of the proposed method. The results verify that the conventional methods are not capable of detecting some PQ disturbances properly, but the proposed WT-based method is more reliable according to the conventional methods.     

Power loss reduction in radial distribution system with multiple distributed energy resources through efficient islanding detection

To provide electric utility service of desired quality at the lowest possible cost, voltage drop and power loss reduction is crucial for distribution network. Distribution systems with Distributed Energy Resources (DER) have shown an enormous potential for power loss and voltage drop reduction. This paper investigates existing islanding detection techniques for feeder performance and proposes a new islanding detection algorithm (NIDA) for node voltage profile improvement and power loss reduction in the distribution network.     

Analysis of active islanding detection methods for grid-connected microinverters for renewable energy processing

This paper presents the analysis and comparison of the main active techniques for islanding detection used in grid-connected microinverters for power processing of renewable energy sources. These techniques can be classified into two classes: techniques introducing positive feedback in the control of the inverter and techniques based on harmonics injection. Accurate PSIM^TM simulations have been carried out in order to perform a comparative analysis of the techniques under study and to establish their advantages and disadvantages according to IEEE standards.     

Supplying the energy of islands with geopolitical positions using distributed generations to increase energy security

The islands usually face challenges in their energy supply due to their specific location. On islands that are distant from the land, power is typically provided by diesel generators. Therefore, oil tankers must regularly refuel the island in order to supply the necessary fuel for diesel generators. As a result, if the fueling procedure is not completed for whatever reason, the island will not receive the necessary energy, which will result in an unavoidable loss of load. Due to their strategic location, some of these islands are used as military islands to protect the nations and waterways. Given the vital role that these military islands play for nations, a delay in supplying the island with energy can seriously harm security, the economy, and other factors. Transferring fuel to these islands is typically difficult, and in some cases impossible, under certain circumstances, such as war. Therefore, reducing the island's reliance on fossil fuels as much as feasible is vital to ensure the energy security of these specific islands. Diesel generators provide electricity to Larak Island, which is situated in the Strait of Hormuz. Larak Island serves as a military island due to its geopolitical location, hence it is crucial to consistently provide Larak with electricity. Therefore, in this paper, a combination of distributed generations and system storage is used to supply the Larak island. The photovoltaic, wind and tidal plants are considered the main power plants, and fuel cells with electrolyzers and hydrogen tanks have also been used as storage systems. In addition, the diesel generator is considered the system backup. The considered objective functions to design and manage Larak island's power supply system are reducing diesel generators fuel consumption, reducing electricity cost, and reducing electricity outages and lost power generation of renewable resources.     

Fuel cells and energy networks of electricity,heat, and hydrogen: A demonstration in hydrogen-fueled apartments

A demonstration was performed to evaluate our proposal of a residential energy system based on fuel cells and energy networks of electricity, hot water, and hydrogen. The demonstration was conducted from April 2007 to March 2009 in a small apartment building constructed for experimental purposes in Osaka City. Three small proton exchange membrane fuel cells were installed, and the electricity and hot water from the fuel cells were shared among 6 units via an internal electricity grid and hot water pipe. A hydrogen production facility, a small storage device, and a hydrogen pipe were installed to supply hydrogen to the fuel cells. Six families went about their normal daily lives using this system. The energy flow from hydrogen production to consumption was demonstrated. The results of fuel cell operation, energy supply, and energy demand, as well as an analysis of primary energy saving and CO₂ emission mitigation are presented.     

A new method of leak location for the natural gas pipeline based on wavelet analysis

This paper analyzes the properties of wavelet transform and its potential application in detecting the leakage location of gas pipeline. An entity-part method, which is proposed for the accurate leaking point, has been proved valid in the stimulation experiment. In addition, method of Romberg and Dichotomy Searching are also adopted for the computational analysis of leaking point. In detail, the effect of gas velocity is taken into consideration in the location formula and we propose to consider the average velocities of two parts caused by the leaking point, respectively. Finally, we test these three methods in a real gas pipeline experiment and the result shows the improvement to some extent in contrast to the traditional approach.     

A new Fuzzy&Wavelet-based adaptive thresholding method for detecting PQDs in a hydrogen and solar-energy powered EV charging station

This study presents a hybrid fuzzy decision-maker (FDM) and un-decimated wavelet transform (UWT)-based method for detecting power quality disturbances (PQDs) in a developed hydrogen and solar energy-powered electric vehicle (EV) charge station. The proposed adaptive FDM&UWT-based hybrid method eliminated the lack of performance of threshold-based signal analysis methods in noise-containing signals and it is implemented for a reliable PQD detection and integration in a developed microgrid. Also, the proposed method has eliminated the need for a processing-intensive filtering process to reduce noise from the signal. With this adaptive approach, detection errors in boundary conditions in threshold value methods are avoided and at the same time, cost and computational burden are minimized by using only the peak values in the detail coefficients of the voltage signal. The mean test accuracy is 96.13% for the FDM method using pyramidal UWT in noise-free conditions. Besides, the pyramidal UWT-FDM has a mean classification accuracy of 94.96% under 20–40 dB high-level noise conditions. The effectiveness of the UWT-FDM method is also tested using an experimental setup. The mean test accuracy for experimental data is 96.66%.     

Assessment and optimization of an integrated energy system with electrolysis and fuel cells for electricity,cooling and hydrogen production using various optimization techniques

In this research study, a novel integrated solar based combined, cooling, heating and, power (CCHP) is proposed consisting of Parabolic trough solar collectors (PTSC) field, a dual-tank molten salt heat storage, an Organic Rankine Cycle (ORC), a Proton exchange membrane fuel cell (PEMFC), a Proton exchange membrane electrolyzer (PEME), and a single effect Li/Br water absorption chiller. Thermodynamics and economic relations are used to analyze the proposed CCHP system. The mean of Tehran solar radiation as well as each portion of solar radiation during 24 h in winter is obtained from TRNSYS software to be used in PTSC calculations. A dynamic model of the thermal storage unit is assessed for proposed CCHP system under three different conditions (i.e., without thermal energy storage (TES), with TES and with TES + PEMFC). The results demonstrate that PEMFC has the ability to improve the power output by 10% during the night and 3% at sunny hours while by using TES alone, the overnight power generation is 86% of the power generation during the sunny hours. The optimum operating condition is determined via the NSGA-II algorithm with regards to exergy efficiency and total cost rate as objective functions where the optimum values are 0.058 ($/s) and 80%, respectively. The result of single objective optimization is 0.044 ($/s) for the economic objective in which the exergy efficiency is at its lowest value (57.7%). In addition, results indicate that the amount of single objective optimization based on exergetic objective is 88% in which the total cost rate is at its highest value (0.086 $/s). The scattered distribution of design parameters and the decision variables trend are investigated. In the next step, five different evolutionary algorithms namely NSGA-II, GDE3, IBEA, SMPSO, and SPEA2 are applied, and their Pareto frontiers are compared with each other.