Mitigation of PtCo/C Cathode Catalyst Degradation via Control of Relative Humidity

Maintaining the high performance of proton-exchange membrane fuel cells (PEMFC) over the course of its lifetime is a key enabling factor for its successful commercialization as a primary power source in zero-emission transportation applications. In this context, it is important to mitigate the degradation of PtCo-alloy based cathode catalysts used for oxygen reduction reaction (ORR). PtCo-alloy catalysts exhibit high activity at beginning-of-life (BOL) which tends to decrease during operation due to loss of electrochemical surface area (ECSA) and dissolution-contamination related effects of the Co-alloying component. Here, we demonstrate the use of relative humidity (RH) of the inlet gases as a controllable parameter to mitigate the degradation of PtCo-alloy catalyst degradation. We employ a catalyst-specific voltage cycling accelerated stress test (AST) durability protocol as a function of inlet RH to degrade PtCo catalysts. A series of in situ electrochemical diagnostics and ex situ characterizations have been carried out to investigate the catalyst layer characteristics at end-of-test (EOT). Our results show that at sub-saturated conditions of durability protocol operation, PtCo catalyst sustains higher EOT H2/air performance due to better retention of ECSA and smaller impact of Co2+ dissolution/contamination.

PRINCIPLES OF IMPROVEMENT OF MULTILEVEL AUTONOMOUS VOLTAGE INVERTERS

The article considers the properties of the most commonly used two-and multilevel inverter topologies used in systems for converting electricity from several primary power sources into the required high-quality output voltage for low-voltage networks and high-voltage consumers. However, a common disadvantage of most known multilevel converters is the increasing complexity of power structures, an increase in the number of primary power sources, power elements, and the cost of devices as the number of their voltage levels increases. Two schemes of alternative three-level autonomous voltage inverters with a high-frequency autotransformer with a midpoint and an example of constructing their digital control system are proposed. The analysis of their work on PSpice models in the OrCAD design system is carried out. The possibility of obtaining six voltage sublevels with fewer power elements and increased output voltage quality is shown, compared to the corresponding cascade multilevel inverters. The advantages and applications of autotransformer bridge voltage inverters in terms of energy and functionality compared to well-known multilevel inverters are presented. Ref. 8, fig. 7.

Hydrogen-Based Energy Storage Systems for Large-Scale Data Center Applications

Global demand for data and data access has spurred the rapid growth of the data center industry. To meet demands, data centers must provide uninterrupted service even during the loss of primary power. Service providers seeking ways to eliminate their carbon footprint are increasingly looking to clean and sustainable energy solutions, such as hydrogen technologies, as alternatives to traditional backup generators. In this viewpoint, a survey of the current state of data centers and hydrogen-based technologies is provided along with a discussion of the hydrogen storage and infrastructure requirements needed for large-scale backup power applications at data centers.

Robust Flatness Tracking Control for the “DC/DC Buck Converter-DC Motor” System: Renewable Energy-Based Power Supply

The design of a robust flatness-based tracking control for the DC/DC Buck converter-DC motor system is developed in this paper. The design of the control considers the dynamics of a renewable energy power source that plays the role of the primary power supply associated with the system. The performance and robustness of the control is verified through simulations via MATLAB-Simulink when abrupt changes in some parameters of the system are taken into account. Also, experiments are performed by using a built prototype of the DC/DC Buck converter-DC motor system, a TDK-Lambda G100-17 programmable DC power supply, MATLAB-Simulink, and the DS1104 board from dSPACE. In this regard, the TDK-Lambda G100-17 is implemented with the aim of emulating photovoltaic panels through the solar array mode for generating the power supply of the system. Thus, both simulations and experiments show the effectiveness of the proposed control scheme.

The constitutional and legal framework for the institutionalization of the Kurdistan Regional Parliament

This research is discussing on the institutionalizing case of Kurdistan Region entity and Kurdistan Parliament as the primary power in its parliamentary political system in the state institutionalizing framework. This insight gives us the opportunity that institutionalization case through state forming module, development and dissolving based on the institutionalization theory should be considered. In this situation, we need to fcus on the most powerful political body in the Region which is the. parliament and its institutionalization framework. The research discusses power and its role with duties to achieve the obligations through the constitutional law and its norms with the tools to facilitate and run its duties. Thus, the main obstacles facing the institutionalization of the Parliament will be known, while the parliament is highly considered by civilians and people of Iraqi Kurdistan.

Comprehensive Review on Fuel Cell Technology for Stationary Applications as Sustainable and Efficient Poly-Generation Energy Systems

Fuel cell technologies have several applications in stationary power production, such as units for primary power generation, grid stabilization, systems adopted to generate backup power, and combined-heat-and-power configurations (CHP). The main sectors where stationary fuel cells have been employed are (a) micro-CHP, (b) large stationary applications, (c) UPS, and IPS. The fuel cell size for stationary applications is strongly related to the power needed from the load. Since this sector ranges from simple backup systems to large facilities, the stationary fuel cell market includes few kWs and less (micro-generation) to larger sizes of MWs. The design parameters for the stationary fuel cell system differ for fuel cell technology (PEM, AFC, PAFC, MCFC, and SOFC), as well as the fuel type and supply. This paper aims to present a comprehensive review of two main trends of research on fuel-cell-based poly-generation systems: tracking the market trends and performance analysis. In deeper detail, the present review will list a potential breakdown of the current costs of PEM/SOFC production for building applications over a range of production scales and at representative specifications, as well as broken down by component/material. Inherent to the technical performance, a concise estimation of FC system durability, efficiency, production, maintenance, and capital cost will be presented.

Efficiency Comparison of DC and AC Coupling Solutions for Large-Scale PV+BESS Power Plants

In large-scale photovoltaic (PV) power plants, the integration of a battery energy storage system (BESS) permits a more flexible operation, allowing the plant to support grid stability. In hybrid PV+BESS plants, the storage system can be integrated by using different power conversion system (PCS) layouts and different charge–discharge strategies. In the AC-coupling layout, the BESS is connected to the ac-side of the system through an additional inverter. In the DC-coupling layout, the BESS is connected to the dc-side, with or without a dedicated dc–dc converter, and no additional inverter is needed. Referring to a 288 MWp PV plant with a 275 MWh BESS, this paper compares the PCS efficiency between AC- and DC-coupling solutions. The power injected into the grid is obtained considering providing primary power-frequency regulation services. A charging and discharging strategy of the BESS is proposed to ensure cyclic battery energy shifting. The power flows in the different components of the system that are obtained under realistic operating conditions, and total energy losses and annual average efficiency are calculated accordingly. Finally, results show a higher efficiency of DC-coupling compared to the AC-coupling layout.

Sampling Primary Power Standard from DC up to 9 kHz Using Commercial Off-The-Shelf Components

In the framework of the empir projects myrails and windefcy, metas developed a primary standard for electrical power using commercial off-the-shelf components. The only custom part is the software that controls the sampling system and determines the amplitude and phase of the different frequency components of voltage and current. The system operates from dc up to 9 kHz, even with distorted signals. The basic system is limited to 700 V and 21 A. Its power uncertainty is 15 μW/VA at power frequencies and increases to 1.8 mW/VA at 9 kHz. With the extension up to 1000 V and 360 A, the system reaches power uncertainties of 20 μW/VA at power frequencies, increasing to 510 μW/VA at 9 kHz. For higher voltages or higher currents, the same principle is used. However, the uncertainties are dominated by the stability of the sources. The voltage and current channels can also be used independently to calibrate and test power quality instruments. Thanks to a time-stamping system, the system can also be used to calibrate phasor measurement units, which are synchronised to utc.

Administrative Collaborationism in the Occupied Districts of the Kaluga Region in the 1941–1943s

On the basis of numerous journalistic and archive material, the article analyzes features characterizing the development of administrative collabora-tionism in various areas of the Kaluga region. The author, using a comparison technique, induction, classification, and synthesis, comes to a conclusion that development of collaboration formation conditions has been influenced by the nature of occupation caused by a certain territory status.At first, the invaders created the most necessary institutions of primary power for them such as chiefs and burgomasters in the cities. Later, during the development of the occupied territory, a system of district, regional and volost administration was formed.The study showed that the activities of the collaborative administration were controversial, they focused both on the direct execution of the German command’s instructions, and relatively on satisfying the requests of the civilian population if these activities did not go to the detriment of the invaders’ interests.