Hasil untuk "Production of electric energy or power. Powerplants. Central stations"

Qinglin Meng, Sheharyar Hussain, Ying He et al.

Rafael S. Salles, Rebecca Asplund, Sarah K. Rönnberg

Francesco Superchi, Antonis Moustakis, George Pechlivanoglou et al.

Lili Pan, Chunyun Fu, Bin Chen

A novel sliding mode control (SMC) strategy incorporating an adaptive super-twisting algorithm is developed for permanent magnet synchronous motors (PMSMs), effectively mitigating high-frequency chattering while enhancing external disturbance rejection capabilities. Initially, a sliding surface is crafted based on the dynamic characteristics of the PMSM and real-time feedback. The super-twisting algorithm is subsequently applied adaptively to dynamically adjust the control effort required to maintain the sliding mode state, thereby ensuring precise and prompt intervention to uphold system stability and enhance response speed. Additionally, in light of operational challenges such as road-induced load disturbances, a Lyapunov-based disturbance observer is proposed for precise load torque estimation in PMSM systems. The efficacy of the proposed control and observation methods is substantiated through a hardware-in-the-loop experiment test, demonstrating that the developed sliding mode controller, leveraging the adaptive super-twisting algorithm, exhibits superior tracking and disturbance rejection capabilities, reduces steady-state current error, and bolsters system parameter robustness, and the modified extended state observer (MESO) exhibits commendable estimation performance.

José Gabriel O. Pinto, João P. D. Miranda, Luis A. M. Barros et al.

This paper presents the design, implementation and experimental validation of a modular battery management system (BMS) featuring active cell balancing. The proposed BMS consists of a master module and multiple slave submodules responsible for monitoring and balancing 22 cells connected in series. The master module collects voltage and temperature data from the slave submodules and measures the battery current to estimate the cells’ state of charge (SoC). Each slave module performs cell voltage and temperature measurements and controls a balancing circuit based on dc-dc converters. This work describes in detail the development and validation of the dc-dc converter based in the switched inductor topology, presenting the converter’s operational principles, a theoretical and simulation-based analysis of its performance, the implementation of the MOSFETs driver circuits based on PNP transistors and experimental results obtained from a submodule prototype. The results demonstrate the capability of the switched inductor converter to achieve effective voltage equalization by transferring energy from the cells with higher voltages to cells with lower voltages.

Tianxiao Yan, Su Guo, Hao Sun

Masoud Shokri, Taher Niknam, Mojtaba Mohammadi et al.

Abstract Smart cities consist of various energy systems and services that must be optimally scheduled to improve energy efficiency and reduce operation costs. The smart city layout comprises a power distribution system, a thermal energy system, a water system, and the private and public transportation systems. Additionally, several new technologies such as reconfiguration, regenerative braking energy of the metro, etc. are considered. This study is one of the first to consider all these technologies together in a smart city. The proposed power distribution system is a grid‐connected hybrid AC–DC microgrid. The biogeography‐based optimization algorithm was utilized to seek the best solution for scheduling micro‐turbines, fuel cells, heat pumps, desalination units, energy storage systems, AC–DC converters, purchasing power from the upstream, distributed energy resources, and transferring power amongst electric vehicle parking stations and metro for the next day. Also, the reduced unscented transformation layout was used to capture the system's uncertainty. The suggested layout is implemented on an enhanced IEEE 33‐bus test system to show the efficiency of the suggested method. The results show that costs and environmental pollution are reduced. By comparing the proposed smart city with other studies, the efficiency and completeness of the proposed smart city are shown.

Marina Martins Mattos, João Antônio G. Archetti, Leonardo de A. Bitencourt et al.

Abstract The decarbonization of the power generation and transport sector encourage the analysis of connection of distributed energy resources (DER), such as electric vehicles (EVs), to the electrical system, as well as the evaluation of their impact on smart cities. A better understanding of the negative impacts on the power systems will lead to propose mitigation measures and eventually revolutionize the way distributed generation works. This paper aims at modelling and evaluating the impact of EVs on a real distribution network. The energy system chosen operates at 60 Hz, 34.5 kV (medium voltage) and 0.208 kV (low voltage) and it is simulated using PSCAD/EMTDC. To reproduce realistic user consumption profiles, dynamic load profiles based on EV owners behaviour have been simulated. The vehicle‐to‐grid (V2G) technology is modelled to mitigate the impacts of high penetration of EVs by supporting the network from undervoltage. The results show the importance of active management in modern power systems, especially considering the increase in DER penetration expected for the coming years. This work shows the benefits of implementing V2G technology while highlighting the challenges involved in a real case.

Longfei Sun, Huiying Gu

Dual–motor drive is commonly used in heavy–duty robotic joint servo systems. However, the backlash inevitably affects joint accuracy. In this article, a variable bias torque control method is proposed for a dual–motor–driven robotic joint. The variable bias torque varies directly according to the motor current, and the conversion method of the bias compensation torque is presented. A simulation model of the dual–motor drive system in MATLAB/Simulink is established based on the dynamic modeling of a dual–motor drive system, and a robotic joint prototype is also established. The variable bias torque control can achieve a reasonable distribution of the output torque for the whole servo cycle and can effectively reduce the energy consumption of the system to maintain static backlash elimination; the dynamic loading of the bias voltage can be achieved through the setting of the conversion function to complete the smooth transition between the two states of backlash elimination control and common drive control; the dynamic loading of the bias torque improves the torque output capability of the dual–motor system. In the experiment, the steady–state error of the servo system is less than 0.05°, and the error is much smaller than the internal backlash angle (about 2°) of the system, which indicates that the internal backlash of the robot joint has been eliminated. The static backlash elimination bias current of the joint is reduced from about 250 mA to about 110 mA, reducing the energy consumption of the servo system effectively.

Wei Gu, Zaiyu Chen, Qun Li et al.

To avoid the secondary frequency dip caused by the steep drop of the electrical power of wind turbines (WTs) at the end of frequency support stage, the torque limit-based iner-tial control (TLIC) method sets the power reference as a linear function of rotor speed, rather than the step form for the step-wise inertial control. However, the compensation effect on the frequency nadir (FN) caused by the load surge is weakened as the TLIC power is no longer in the step form. Specifically, the maximum point of the frequency response component (FRC) contributed by TLIC occurs earlier than the minimum point of FRC corresponding to the load surge, so that the FN cannot be adequately raised. Therefore, this paper first investigates the relation between the peak and nadir times of FRCs stimulated by the TLIC and load power. On this basis, with the compensation principle of matching the peak and nadir times of FRCs, the improved TLIC method based on delayed support is proposed. Finally, the effectiveness of the proposed method is validated via the experiments on the test bench of wind-integrated power system.

Jianlin Li, Zhijin Fang, Qian Wang et al.

As renewable energy continues to be integrated into the grid, energy storage has become a vital technique supporting power system development. To effectively promote the efficiency and economics of energy storage, centralized shared energy storage (SES) station with multiple energy storage batteries is developed to enable energy trading among a group of entities. In this paper, we propose the optimal operation with dynamic partitioning strategy for the centralized SES station, considering the day-ahead demands of large-scale renewable energy power plants. We implement a multi-entity cooperative optimization operation model based on Nash bargaining theory. This model is decomposed into two subproblems: the operation profit maximization problem with energy trading and the leasing payment bargaining problem. The distributed alternating direction multiplier method (ADMM) is employed to address the subproblems separately. Simulations reveal that the optimal operation with a dynamic partitioning strategy improves the tracking of planned output of renewable energy entities, enhances the actual utilization rate of energy storage, and increases the profits of each participating entity. The results confirm the practicality and effectiveness of the strategy.

Shuaibin Shi, Yongli Liu, Qing Wang et al.

Abstract The access of electric vehicle charging stations (EVCS) brings challenges to the stable operation of the distribution network.At present, there is a lack of indicator to quantify the economic losses caused by the decrease in power quality of the distribution network due to the access of EVCSs.In the paper, the travel trajectories of electric vehicle users are constructed through trip chain and state transition matrices,thereby obtaining the spatiotemporal distribution of charging loads.In addition, the voltage deviation and line loss caused by charging loads are unified into economic indicator to quantify.The simulations are conducted in a road network coupled to the IEEE 33-node distribution network.The result shows that the charging load of electric vehicle charging stations have a significant impact on the power quality of the distribution network.At the same time, optimizing the location of charging stations and guiding electric vehicle users’ charging behaviorcan effectively improve the power quality and economic efficiency of distribution networks.

Bo Chen, Zhuoma Qiong, Fu Liu et al.

Łukasz Topolski

Duża koncentracja jednofazowych mikroinstalacji fotowoltaicznych w nisko obciążonej sieci dystrybucyjnej niskiego napięcia często ma negatywny wpływ na parametry jakości energii elektrycznej, co skutkuje automatycznym wyłączaniem się falowników oraz utrudnia służbom energetycznym prowadzenie prac eksploatacyjnych z wykorzystaniem agregatów prądotwórczych. W artykule wyjaśniono i przedstawiono wpływ jednofazowych mikroinstalacji fotowoltaicznych o mocy 2 kW na wartość skuteczną napięcia i asymetrię prądową i napięciową oraz omówiono współpracę agregatu prądotwórczego z mikroinstalacjami. W artykule zaprezentowano również wyniki pomiarów skuteczności łagodzenia negatywnego wpływu mikroinstalacji na parametry napięcia za pomocą transformatora symetryzującego oraz szeregowego transformatora dodawczego, z niezależną regulacją napięcia w poszczególnych fazach.

Shaohua Lu, Enhao Lu, Kai Zhu et al.

Potassium ion batteries (KIBs) have received increasing popularity owing to their distinct advantages. We discover a hitherto unknown C₄S nanosheet, a novel carbon-based material with carbon and sulfur consisting of pentagons and hexagons rings. The proposed C₄S nanosheet is highly stable dynamically, thermodynamically, mechanically, and chemically, according to first-principles calculations. Moreover, the graphene-like C₄S nanosheet is a prospective KIBs anode material, which has a metallic band structure, a relatively low diffusion barrier (0.07 eV), a large capacity (1340 mA h g⁻¹), and an acceptable average voltage (0.44 V). Finally, we demonstrate good cycling stability of the C₄S nanosheet. Our findings indicate that the proposed C₄S nanosheet is a potentially favorable KIBs anode material.

Fan Li, Tao Niu, Lin Xue et al.

Determining security/stability boundaries is a common and critical means of preventing cascading failures induced by voltage-related issues, which represents one of the major challenges in bulk power systems. However, traditional approaches suffer from conservative issues and heavy computational burdens. To address these challenges, the concept of an autonomous-synergic voltage security region (AS-VSR) and the corresponding dynamic constraint coefficient pruning (Deep) computation method, which fully consider the volt/var characteristics of bulk power systems, are proposed in this letter. Both linearized and nonlinearized robust optimization problems are introduced to obtain accurate results. The computational accuracy, time cost, and advantages of autonomous-synergic control are observed in the simulation results.

Hai-Tao Qi, Dong-Ao Zhao, Duo Liu et al.

The electro-hydrostatic actuator (EHA) is the key component of most electric aircraft, and research on its fault diagnosis technology is of great significance to improve the safety and reliability of aircraft flight. However, traditional fault diagnosis methods only focus on partial failures and cannot completely diagnose the whole EHA system. In this paper, the progressive fault diagnosis method (PFDM) is proposed for overall diagnosis of whole EHA system, which can be divided into four levels for health detection and fault diagnosis of the overall EHA system. PFDM combines fault diagnosis methods based on Kalman filter, threshold, logic, and EHA system analysis model to diagnose the whole EHA system layer by layer. At the same time, in order to ensure the normal operation of the EHA system after fault diagnosis, double redundancy design is creatively carried out for the EHA system to facilitate system reconstruction after fault detection. It can be continuously modified according to different EHA system parameters and measured signals to improve the accuracy of fault diagnosis. The experimental results show that PFDM can accurately locate and identify 22 faults of the double redundancy EHA system by using the accurate EHA system mathematical model. PFDM improves the fault diagnosis response time to 4 ms, greatly improving the safety and reliability of the double redundancy EHA system.

P. V. Rotov, A. A. Sivukhin, M. A. Rotova et al.

PURPOSE. Perform analysis of the actual heat energy consumption for cold water heating for the hot water utility to the approved standard. Compare different methods of flow control in circulation pipelines of hot water supply systems. Identify ways to improve the efficiency of hot water systems. METHODS. The passive engineering experiment was used to study the operating modes of hot water supply systems of several groups of houses, in which various methods of regulating water consumption in hot water supply systems are implemented. Data collection was carried out using the online system of control and commercial accounting of energy resources. RESULTS. Existing hot water supply systems in residential buildings of Ulyanovsk were inspected under various methods of flow control in circulation pipelines. Features of static and dynamic load control of hot water supply systems were investigated. Analysis of influence of methods of control of thermal load of hot water supply systems on their actual heat consumption was performed. The possibility of bringing the actual operation mode of hot water supply systems to the standard value, on the basis of which consumption is calculated, is estimated. CONCLUSION. Known methods of load control in hot water supply systems and their actual operating conditions do not allow to reach the level of heat consumption that meets the established standards. Conclusions were drawn on the need to revise the regulated indicators of hot water quality and to adjust the method of calculating consumption in hot water supply systems.

Hui LIU, Qianjun JIANG, Qianjin GUI et al.

Power grid outage decision-making for maintenance significantly affects the power supply reliability and customer’s satisfactions. The actual maintenance schedule for power grid is subjected to the subjective experience decision-making which is suitable for single maintenance outage plan. However, this method is difficult to achieve the optimal decision-making for multiple outage events, and the existing scheme only considers reducing the amount of outage power, instead of the interests of both the maintenance side and the user side. Therefore, we propose an optimal decision-making method for multiple outage events with consideration of the comprehensive supply-demand factors. Firstly, an outage decision-making model is established for optimal power grid maintenance scheduling with consideration of multiple outage events. In this model, the multi-objective function is constructed with minimized power outage (at grid side), minimized disappointment degree of user’s power consumption (user side) and maximized difference degree of equipment outage time (maintenance side), and the constraints of outage power and special events are used as constraint functions. Secondly, in order to improve the optimization efficiency, a single-objective function optimization model is constructed for optimal power grid outage decision-making based on the proportional coefficient method. Thirdly, a fitness optimization model is constructed based on the penalty function, and the genetic algorithm is used to solve the optimal outage decision-making problem. Finally, a real power grid case is used for simulation analysis, which has verified the correctness and effectiveness of the proposed model and algorithm.

Dmitri Burdin, Dmitri Chashin, Leonid Fetisov et al.

Magnetoelectric (ME) effects in composite ferromagnet-piezoelectric (FM/PE) heterostructures realize the mutual transformation of alternating magnetic and electric fields, and are used to create magnetic field sensors, actuators, inductors, gyrators, and transformers. The ME effect in composite structures is excited by an alternating magnetic field, which is created using volumetric electromagnetic coils. The coil increases the size, limits the operating frequencies, and complicates the manufacture of devices. In this work, we propose to excite the ME effect in composite heterostructures using a new coil-free excitation system, similar to a “magnetic capacitor”. The system consists of parallel electrodes integrated into the heterostructure, through which an alternating current flows. Modeling and measurements have shown that the excitation magnetic field is localized mainly between the electrodes of the magnetic capacitor and has a fairly uniform spatial distribution. Monolithic FM/PE heterostructures of various designs with FM layers of amorphous Metglas alloy or nickel-zinc ferrite and PE layers of lead zirconate titanate piezoceramic were fabricated and investigated. The magnitude of the ME effect in such structures is comparable to the magnitude of the ME effect in structures excited by volumetric coils. However, the low impedance of the coil-free excitation system makes it possible to increase the operating frequency, reducing the size of ME devices and the power consumption. The use of coil-free excitation opens up the possibility of creating planar ME devices, and accelerates their integration into modern electronics and microsystem technology.