Centralized Power Research Articles

Expanding lake and the landless pastoralists in pastoral Tibet, China

ABSTRACT This paper argues that everyday politics are instrumental in negotiating development outcomes despite the pervasive influence of centralised state power. The paper highlights the fluidity and adaptability of Chinese policy formulation, emphasizing local learning and improvisation. This is especially important for pastoral communities in remote rangelands, where land appropriation and environmental exploitation are increasingly evident. The paper sheds light on the influential role of everyday political practices in shaping outcomes within the Chinese context, while simultaneously contesting simplistic portrayals of top-down state planning in China. By emphasizing the existence of manoeuvrability and opportunities for negotiation within this framework, the paper advocates for a nuanced understanding of governance dynamics and power relations in the Chinese context.

On the Effect of Current Stabilizer on Dynamics of a Small Hybrid Wind Power Generator

The use of small wind power generators remains quite relevant. In particular, they can be efficient for charging batteries in remote locations where there is no centralized power supply (including in the Arctic, Far East, etc.). They can also be used as part of missions to planets with atmospheres. One of the promising design solutions for a small wind power generator with a vertical axis of rotation is a hybrid device. It consists of two wind turbines that have a common axis of rotation: external (Darrieus wind turbine) and internal (Savonius rotor). This scheme represents a compromise between the relatively high power coefficient of the Darrieus turbine and the good startup characteristics the Savonius rotor. It is known that one of the typical battery charging modes is constant current charging. Here we consider a hybrid installation, the generator of which is connected to a current stabilizer. The load is simulated with an active resistance. It is assumed that the generator is a DC generator. A closed mathematical model of the studied system is constructed. The aerodynamic load is described using the quasi-steady approach. It is assumed that the characteristic time of electrical processes is much smaller than the characteristic time of mechanical processes. The influence of load resistance on the behavior of the system is investigated. It is shown that, under certain conditions, several steady modes (up to five) exist in the system. In this case, at least two of them are attracting. Therefore, the hysteresis of the angular speed of the steady mode is possible when the load resistance changes. It should be noted that in a number of situations, an unstable steady mode (which corresponds to a lower angular speed of the turbine than a stable one) may be preferable (for example, to reduce the load on bearings). In this regard, a resistance control strategy has been proposed to ensure stabilization of the unstable stationary regime.

Supervisory control strategy for dual battery assisted solar water pumping using a 3-stage interleaved boost converter

This article proposes effective power management and battery protection strategies for a solar photovoltaic (SPV) powered dual-battery supported standalone water pumping approach propelled by a permanent magnet brushless direct current (PMBLDC) motor. A drift-avoidance perturb and observe MPPT algorithm is employed in conjunction with a 3-stage interleaved boost converter (TSIBC) and proposes a switching control scheme to enable double-stage solar photovoltaic generation system (SPGS) to operate at its maximum accessible power point (MPP) irrespective of any variation in climatic condition. The proposed dual battery control scheme (DBCS), which integrates a primary battery with an auxiliary battery, is connected to the 310 V DC link. This dual battery setup utilizes a parallel-active configuration facilitated by two bidirectional DC-DC converters (BDCs). The core idea behind dualization aims to maintain the state of charge (SoC) of the primary battery within upper and lower limits with the help of an auxiliary battery unit and regulate the DC link voltage at 310 V during fluctuations generated in the protection period. This scheme significantly extends the battery's lifespan, achieving an estimated 800 to 1000 cycles by maintaining its depth of discharge (DoD) at a level of 70 %. A centralized power handling unit (CPHU) is integrated for both the BDCs to facilitate the operating mode selection and regulate DC link voltage by alternatively charging/discharging both batteries. This approach enhances overall system efficiency by eliminating the need to oversize the solar array by up to 46 %, which would have been necessary to fully charge both batteries simultaneously. Previously, the DC link voltage regulation relied solely on MPPT control, resulting in significant deviations (up to ±38.43 %) during battery overcharging/deep-discharging (SoC ≥ 90 %/SoC ≤ 20 %). This work proposes a solution using an auxiliary battery controller within the DBCS, achieving near-zero (±0.5 %) DC link voltage deviation under all operating conditions. The effectiveness of the suggested DBCS controller is validated through a time-domain simulation conducted in MATLAB/Simulink, alongside real-time hardware-in-the-loop (HIL) digital simulator using the OPAL-RT platform. The acquired results corroborate enhanced performance for the standalone water pumping system (WPS) and demonstrate a seamless shift from the normal operational mode to battery protection mode, while ensuring steady regulation of the DC link voltage.

Integrated RES With Intelligent MPPT For Efficient Power Generation & Wireless Transmission for PV Applications

The increasing global energy demand and the urgent need to shift to sustainable practices have made the integration of renewable energy sources (RESs) into distribution power systems imperative. This project's main objective is to implement rooftop photovoltaic (PV) systems as an essential part of low-voltage (LV) DC networks' building-integrated centralized generation Maximum Power Point Tracking (MPPT) using Artificial Neural Networks (ANNs) is used to maximize power extraction from photovoltaic (PV) panels and boost power generation efficiency, particularly in partially shaded circumstances. After that, the PV system's generated power is sent to a Luo converter, which effectively tracks and optimizes the power production. For wireless power transmission, the Luo converter's output is then fed into a high-frequency converter. This wireless power transmission improves the system's adaptability and scalability by facilitating smooth energy transfer without the requirement for physical connections. An isolation transformer is attached to the high-frequency converter's output in order to guarantee the system's dependability and safety. The high-frequency converter is isolated from the downstream components by the isolation transformer, which also offers protection against electrical risks. Finally, a battery made especially for use in electric vehicle (EV) applications receives the transformer's isolated output, which is also supplied to DC loads. Finally, we will use the MATLAB 2021a / Simulink program to do a number of numerical simulations in order to validate the suggested controls. The output voltage of 130v is stored in the battery if a voltage of 65 v is taken as output from the photovoltaic system.

Research on optimal scheduling strategy of source-grid-load-storage in rural low-voltage distribution network

The increasing demand for centralised power consumption in rural agriculture may result in low voltage and three-phase imbalance issues at the end of the distribution network. Furthermore, the extensive implementation of distributed photovoltaic (PV) systems may cause an imbalance between agricultural power load and PV output, exacerbating the issue of PV losses. In this paper, an optimal scheduling strategy for an integrated source-networkload- storage system is proposed to solve the above problems. The proposed strategy involves a dispatch model that includes PV power generation and energy storage, with the objective of maximising PV consumption and minimising operating costs. The PPO algorithm is finally employed to solve the cooperative optimisation model for source-grid-load-storage. The proposed scheduling strategy has been validated through examples, and the results demonstrate its effectiveness in ensuring the economic and safe operation of rural distribution networks.

A centralized power prediction method for large-scale wind power clusters based on dynamic graph neural network

The uncertainty of the wind process leads to the randomness of its regional propagation, and the spatial correlation between nearby wind farms also shows a dynamic change tendency under the influence of wind direction. To consider the influence of dynamic spatial correlation on wind power prediction modeling, a short-term wind power prediction method based on a dynamic graph neural network is proposed. First, the topology graph of the wind farm cluster was established to represent the correlation of wind farms based on graph theory. Then, a dynamic spatiotemporal graph neural network was constructed to adapt graph topology by node embedding, which can explore the changing characteristics of spatial correlation among wind farms. Finally, we proposed a decoupling error model that can quantify the proportion of errors caused by the modeling process, which can assist in evaluating the performance of predictive models. We conducted experiments using data provided by the wind farm cluster in Inner Mongolia, and the average normalized Root Mean Square Error for the 12 wind farms was 0.1424, which verified the effectiveness of the proposed model.

Power to the People: Advancing Resilient and Sustainable Decentralized Energy Distribution Systems

This research explores decentralized energy distribution systems (DEDs) as a transformative approach to modernizing power grids. DEDs, including solar photovoltaics, wind turbines, microgrids, and battery storage, offer localized, resilient, and sustainable alternatives to traditional centralized power systems. This study examines the technological components, economic and environmental impacts, policy frameworks, and the challenges associated with DED implementation. Through a comprehensive analysis of case studies and current advancements, we highlight the potential of DEDs to enhance energy security, reduce carbon emissions, and promote economic development. By addressing technical and social challenges, this paper underscores the critical role of innovative solutions, such as artificial intelligence and blockchain, in optimizing decentralized energy systems. The findings contribute to a deeper understanding of how decentralized energy can support global sustainability goals and pave the way for a resilient and efficient energy future.

Multi-objective Harris Hawks optimization algorithm for selecting best location and size of distributed generation in radial distribution system

Distributed Generating Units (DGUs) are widely used in backup power, renewable energy integration, voltage regulation, and energy storage applications. The DGUs are small-scale power-generating units located near the load centers of a power system, as opposed to large, centralized power plants located far away. However, the DGUs must reduce power losses and environmental impacts and improve the voltage profile. This was achieved by effective optimization of the position and rating of DGU. However, the conventional optimization methods failed to optimize the power losses, voltage-current balancing issues, and harmonic distortions. So, this article presents the selection of the best location and size of DGU in radial distribution systems using a nature-inspired multi-objective Harris Hawks optimization (HHO) algorithm while considering improvements in the voltage profile and reductions in active power losses. The HHO algorithm is inspired by the supportive actions of intelligent birds, such as Harris Hawks, while searching for prey. The distinguished hunting process of Harris Hawks using other family members makes it unique, which is useful for searching for better quality solutions while optimizing multi-objective fitness functions. Fitness function is determined by considering each bus's voltage profile and branches' active power losses. The proposed method is tested on two circle distribution systems (69 bus and 118 bus). The results are compared to those obtained using some of the more well-known optimization techniques given by scholars in recent years. The optimization of seven DGU in 118 bus radial distribution systems resulted in 405.32 kW of active power losses, a 68.78% decrease in losses, and 0.9723 Vs of minimum voltage.

БАГАТОРІВНЕВІ ГНУЧКІ СИСТЕМИ РОЗПОДІЛУ ЕЛЕКТРИЧНОЇ ЕНЕРГІЇ

In the conditions of a long-term threat of the destruction of the energy structure, the distribution networks of our country need to change the principles of their construction. For this purpose, a multi-level structure of the construction of the distribution system is proposed. Such a structure, due to the use of modern hardware solutions and extensive involvement of local energy resources, makes it possible to ensure a high level of their flexibility. In order to maintain power supply to the maximum number of consumers in the event of damage of varying severity and duration that may occur in the centralized power supply system. References 9, figures 2.

Optimal planning and operation of integrated energy systems in South Korea: Introducing a Novel ambiguity set based distributionally robust optimization

In this paper, we address the increasing focus on Renewable Energy Sources (RES) and energy policies in S. Korea, advocating for a shift from large, centralized power systems to decentralized Local Power Systems (LPS). This transition emphasizes the integration of Integrated Energy Systems (IES), which significantly enhances the target benefits for stakeholders in the power system. We have also adopted a Distributionally Robust Optimization (DRO) approach to account for the output uncertainty of RES and developed and applied new ambiguity sets tailored to each RES, enhancing the extensive robust design previously utilized with DRO. By applying our proposed ambiguity set-based DRO, we avoid excessive robustness and achieve superior optimal outcomes compared to the general DRO methodology, potentially making a significant contribution to business investment decisions. We have categorized the main stakeholders of the power system as Independent Systems Operators (ISO), Renewable Energy Providers (REP), Energy Exchange Aggregators (EXA), and End-users. The integration of IES leads to a benefit improvement rate of up to 34.8 %, 23.0 %, and 24.2 % for ISOs, REPs, and End-users, respectively, on a global scale. EXAs can secure an annual economic profit of up to $191,362.

INTEGRATION OF HYBRID ENERGY PLANT OPERATION

Integrated use means the use of several energy sources, all at the same time or in some combination. At the same time, it is possible to use exclusively renewable sources, which significantly limits user capabilities. More common and justified from many points of view is the use of both renewable and traditional sources, autonomous (universal boilers, diesel generators, gas turbine units, etc.) or centralized (power grid) sources. A correct assessment of such a combined energy system also requires taking into account the main component of the system - the consumer, that is, taking into account the features of the local network and nearby consumers, which will have a direct or tangible indirect effect on the operating mode of the complex of renewable sources. To ensure adequate power quality, energy storage systems can be used, and the need for them depends on the discreteness of energy flows and the requirements for power quality. In foreign terminology, combined systems are often called hybrid, reflecting the diversity of both energy sources and methods of combining them (sometimes this name extends to arbitrary complexes). However, the term “hybrid power supply” usually refers to a combination of installations using renewable and traditional energy sources. The article presents a new hybrid energy system that provides private households with electricity, hot water supply, heating and hot air in the required temperature range for comfortable living. Together with a wind power generator and an electric water heater, a heat pump, electricity and heat accumulators are used, which allows: - reducing the cost of thermal energy by reducing material consumption and equipment costs, saving organic fuel; produce electricity and send the excess to the state power grid; reduce heat load and environmental pollution. The automation system allows you to control the hybrid installation without human intervention all year round.

ФОРМУВАННЯ ЛОКАЛЬНИХ ЕЛЕКТРОЕНЕРГЕТИЧНИХ СИСТЕМ В СКЛАДІ ОБ’ЄДНАНОЇ ЕЛЕКТРОЕНЕРГЕТИЧНОЇ СИСТЕМИ

At present, renewable sources of energy (RSE) are geographically diffused in energy supply systems, which complicates the formation of local electric energy systems (LEES), which operating in normal modes in parallel with the energy system as balancing groups, in extreme cases can operate in isolation in autonomous mode. However, the diffuse distribution of RSE does not allow for the effective formation of LEES in such a way that they ensure the required level of reliability of electricity supply to electricity consumers. The article proposes to integrate RSE into distribution power grids in the form of separate microgrid (MG), which is a key part of the transition to a power grid operating on the principles of SMART Grid. Local MGs, in addition to generation sources and consumers, also have the means to accumulate a certain amount of energy. To ensure the technical and economic efficiency, MGs are combined into an intelligent control system, which allows for more rational use of MG resources, efficient interaction with the distribution grid, and the use of active electricity consumers in the process of balancing the LEES mode. The paper proposes a hierarchical structure of the intellectual system of LEES. Thus structured, LEES with intelligent power grids can not lose RSE during the limitation of centralized power supply, but fully use their advantages together with energy storage systems for reliable power supply to consumers. Thanks to the intelligent system proposed in this paper, the LEES implements the principles of SMART Grid and functions as an informative energy system. The LEES formed in this way can operate as a balancing group within the ESS, performing the tasks of the distribution system operator depending on the voltage and power of its MG components. Since LEES are a part of the ESS, they operate under the conditions and according to the rules, without disrupting the functioning of the ESS, which currently provides a stable power supply. This applies to all modes of operation of LEES.

Sustainable All-Day Thermoelectric Power Generation From the Hot Sun and Cold Universe.

Energy conversion from the environment into electricity is the most direct and effective electricity source to sustainably power off-grid electronics, once the electricity requirement exceeds the capability of traditional centralized power supply systems. Normally photovoltaic cells have enabled distributed power generation during the day, but do not work at night. Thus, efficient electricity generation technologies for a sustainable all-day power supply with no necessity for energy storage remain a challenge. Herein, an innovative all-day power generation strategy is reported, which self-adaptively integrates the diurnal photothermal and nocturnal radiative cooling processes into the thermoelectric generator (TEG) via the spectrally dynamic modulated coating, to continuously harvest the energy from the hot sun and the cold universe for power generation. Synergistic with the optimized latent heat phase change material, the electricity generation performance of the TEG is dramatically enhanced, with a maximum power density exceeding 1000mWm-2 during the daytime and up to 25mWm-2 during the nighttime, corresponding to an improvement of 123.1% and 249.1%, compared with the conventional strategy. This work maximizes the utilization of ambient energy resources to provide an environmentally friendly and uninterrupted power generation strategy. This opens up new possibilities for sustained power generation both daytime and nighttime.

"For Friendship and Peace": Socialist Romania's International Pioneer Camps in the Aftermath of War (1949-1959)

Situated at the intersection of studies of socialist internationalism and youth, this paper explores the origins and character of Romania’s international pioneer camps and youth exchanges in the immediate postwar decade, from 1949 through the late 1950s. It examines the role played by the Soviet model of socialist internationalism in the development of Romania’s camps and youth exchanges as well as the diplomatic, pedagogical, and medical aims international pioneer camps were expected to fulfill for Romania’s fledgling regime of popular democracy. The few existing works on the evolution of mass youth organizations and the reforms of education in Romania assume the existence of an all-powerful regime and party, who enforced these measures from above, having centralized state power and nationalized property and economic resources. Through an examination of the first international camps organized on the Black Sea Coast and in the Carpathian Mountains in Romania, this study nuances such views, suggesting that the newly created youth and children’s organizations – The Workers’ Youth Union and the Pioneer Organization – were precarious party structures, which lacked politically trustworthy and ideologically trained cadres as well as material and administrative resources to assume full control of the country’s youth in the immediate postwar years

Tracking of car body vibration performance of centralized power EMU

The centralized power EMU is a new type of passenger transport vehicle in the process of upgrading the transportation equipment of China’s ordinary speed railways. It can significantly improve the transportation efficiency and passenger comfort of ordinary-speed railways. Detailed research on its dynamic performance during service can guide the widespread use and maintenance of this type of EMU. This paper conducted long-term tracking tests on a centralized power EMU. It analyzes the dynamic performance and evolution rule of the centralized power EMU during long-term service from the perspectives of wheel wear and car body vibration. It compares the performance differences between the control and the trailer car. In the tracking experiment, it was found that the car body exhibits vertical low-frequency vibration. Many experimental studies have shown that the frequency at which the vehicle passes through a bridge that stretches across a distance of 32 meters on the bridge pier at 160 km/h is 1.3 Hz, which excites the nodding mode and causes significant vertical harmonic vibration of the car body.

Research on long term tracking of centralized power EMU wheel wear and vibration performance

The centralized power EMU is a new type of passenger transportation equipment for ordinary-speed railways in China, which can greatly improve the efficiency of ordinary-speed railway passenger transportation and improve passenger travel conditions. This paper conducts long-term dynamic tracking experiments on this new type of railway passenger car, studying the evolution laws of wheel wear, axle box vibration, bogie frame vibration, and car body vibration during long-term service, and analyzing typical vehicle dynamics phenomena that occur in long-term tracking experiments. Various studies have shown that the vehicle can maintain good lateral stationarity throughout the entire wheel reprofile cycle, and the growth rate of equivalent conicity gradually slows down as the mileage increases; However, when the mileage after wheel reprofiling is large, harmonic vibration may occur in individual sections of the frame, leading to abnormal vibration of the control car body at 10 Hz. The vertical vibration of the axle box will significantly increase at the rail joint, and its 70 Hz vibration is transmitted to the frame through the experiment suspension, stimulating the bending mode of the crossbeam of the frame, resulting in a more obvious 70 Hz vibration in the vertical direction of the frame. The RMS of the axle box, frame, and body sleeper does not show significant changes with the rise in mileage following wheel reprofiling.

Control techniques for microgrids networks with energy storage systems: An overview

Microgrids (MG) are localized, self-sufficient energy networks which utilize distributed energy sources to improve dependability, resiliency and long-term viability in decentralized energy production. Network Energy Storage Systems (ESS) have been recognized as critical facilitators within the transitioning from the conventional centralized power system into a sophisticated, self-sustaining, as well as decentralized systems based on renewable energies. Controlling distributed energy storage entails coordinating the administration of several lesser energy storages, which are generally integrated in MGAs consequence, there have been an increase in fascination with regulating elements of sharing power balance and sustainable development, boosting the system's resilience including dependability, along with maintaining a distribution State of charge (SoC). The present research provides a detailed overview of decentralized, centralized, multiagent, and intelligent controlling techniques for managing and regulating distributed energy storages. It also illustrates a possible range of functions which the storages might supply, as well as the controlling challenges and recommended solutions. This research major purpose is to represent current breakthroughs in digitalization by focusing on controlling techniques that depend on multiagent communications.

СРАВНИТЕЛЬНАЯ ОЦЕНКА СХЕМ ПЛАВНОГО РЕГУЛИРОВАНИЯ МОЩНОСТИ ГАЗОГОРЕЛОЧНОГО УСТРОЙСТВА

Large-scale gasification of agricultural enterprises, personal subsidiary plots and farms, for which the most energy-intensive processes are the preparation of feed, food, and home heating, has revealed the need to automate digesters. The peculiarity of the operation of digesters is due to the fact that as the contents of the cooking container are heated to boiling temperature, the heat consumption decreases, and when the product boils, the heat consumption drops below 10%. It has been established that the lack of automatic gas control leads to excessive heat release into the atmosphere during the combustion of gaseous fuel. Previously, a gas burner unit was developed based on a partially automatic industrially produced gas burner device of the AGU-T-M type for digesters, which makes it possible to regulate gas flow in proportion to the consumed heat flow. The task was set to develop a promising scheme that would make it possible to regulate the gas flow in the digester in proportion to the consumed heat flow. This article describes two variants of schemes for proportional control of gas flow in a digester: the first is an improved scheme based on an automated gas burner device of the AGU-T-M type; the second is a circuit developed on the basis of Peltier semiconductor modules, a control solenoid with a gate valve. An assessment is given indicating the advantages and disadvantages of these schemes. It is shown that the first scheme is efficient and energy-independent; its use is most effective in remote settlements where there are frequent interruptions in the centralized power supply. The second scheme corresponds to the latest achievements of scientific and technological progress.

THE ROLE OF DISTRIBUTION SYSTEM OPERATORS IN THE DECENTRALIZED POWER SYSTEM

The paper aims to review some of the available literature concerning the traditional roles of DSOs and the evolution paths suggested by existing academic papers and concrete examples from the industry of what is being done in European Union countries. Furthermore, the roles of DSOs in Romania and the transition to a decentralized power system were investigated. The research hypothesis is that in the following years, DSOs' activity must change to accommodate the shift towards a decentralized power system. The authors determined the driving factors of change for DSOs in the context of energy transition and the role of DSOs in the current centralized power system.

Thermo-economic analysis of an integrated combined heating, cooling, and power unit with dish collector and organic Rankine cycle

In recent years, the integration of renewable resources into simultaneous production systems has resulted in a substantial reduction in fuel consumption when compared to the conventional methods. This study focuses on the design and modeling of a CCHP (combined cooling, heating, and power) system for the campus of Faculty of New Sciences and Technologies, University of Tehran. The system harnesses the primary energy and heat derived from a dish collector and natural gas, while electricity generation is facilitated by a Brayton cycle. Additionally, two organic Rankine cycles recover the waste heat and generate supplementary electricity downstream of the system. The total efficiency of this system attained 79%, and the total exergy efficiency of the CCHP reached 48%. When examining the economic sector, noteworthy savings can be observed, compared to a centralized power generation system. This can be attributed to a 37% reduction in fuel consumption, resulting from the adoption of the dish collector as the primary supplier. Overall, this is a novel setup that involves two stages of ORC, along with a dish collector and combustion chamber that supply the microturbine. The proposed system in this article could be a guide for novel commercial and residential systems in the future.