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

K. M. Sanjeeva Kumar, Satyajit Das, Rajesh Kumar Lenka et al.

Xincheng Zheng, Guibin Zou, Qingquan Li

The access of high penetration distributed generation (DG) seriously affects the reliability of traditional overcurrent protection in active distribution networks (ADNs). Therefore, this paper pro-poses a pilot protection method based on positive sequence additional impedance (PSAI). The PSAI is calculated by positive sequence phasors on the both ends of the protected feeder. When an internal fault occurs, the amplitude of the PSAI is close to the transition resistance which is a relatively small value, while that is theoretically infinitely great when an external fault occurs. Because the PSAI depends only on the faulty type and transition resistance, the proposed method is independent of the power source characteristics. The PSCAD simulation results prove that the method is immune to time synchronization error, has a stronger ability to withstand transition resistance than traditional current differential protection, and can not only adapt to the high penetration of DG, but also has high sensitivity even if DG exits. Finally, protection prototypes with proposed method and 5G communication function are developed. The real time digital simulation closed-loop test results indicate that the protection prototypes can correctly identify internal and external faults with an accuracy of 100 %.

Yi Wang, Junyong Wu

The high penetration of distributed photovoltaic (DPV) systems in distribution networks (DNs) can lead to a series of issues such as reverse power flows and voltage violations, posing a significant threat to the safe operation of DNs. Achieving the minimum curtailment of DPV in DNs is one of the most direct and cost-effective means to ensure their safe operation and effectively utilize renewable energy sources under existing conditions. Introducing the concepts of PV moments and load moments, the moment difference analysis theory (MDAT) for DNs with DPV is proposed. This theory transforms the integration challenge of DPV into a problem of balancing the moment difference (MD) equations for power restoration and maintenance. For a given DN, when the highest node voltage reaches the specified voltage limit, the MD, defined as the difference between PV moments and load moments, approximates a constant known as the critical moment difference (CMD). This CMD is determined by the topological structure and line parameters of the DN, independent of load distribution and PV deployment. The theoretical derivations and case studies confirm this concept. The CMD represents the limit of a DN’s capacity to integrate DPV. The DPV moment is the quantity that the DN needs to accommodate, while the load moment serves as the resource for accommodating the PV moment. Based on MDAT, a method for the minimum curtailment of DPV in DNs is proposed and applied to the analysis and calculations of a 10 kV feeder line at Sichakou of the State Grid Shandong Electric Power Company and the 12.66 kV IEEE 33 bus and 69 systems. The case studies demonstrate that, compared to traditional particle swarm optimization (PSO) methods, the minimum PV curtailment strategy presented in this paper increases optimization speed by 4736.82 times under an error margin of 0.6 %. This validates the correctness and rapidity of the method, making it suitable for real-time optimization and scheduling for minimum PV curtailment in DNs.

Shubhankar Kapoor, Adrian G. Wills, Johannes Hendriks et al.

Grid models, including line impedances, are crucial for the active management and operation of the distribution grid (DG). This paper introduces a novel approach for estimating DG line parameters using available voltage magnitude and node powers from smart meters (SMs), specifically addressing scenarios with missing measurements. We propose an expectation–maximization (EM) based approach and validate the results on an IEEE 37-node network, achieving accurate estimates for line parameters, voltage magnitude, and active/reactive power at nodes. The method is tested with varying levels of missing measurements and noise. Two cases of missing measurements are considered: random and specific node-based. The latter case is used to infer the optimal placement of measurement devices. Additionally, the proposed method is validated on simulated data and real-world consumer loads, consistently providing accurate results.

Zhaoqiang Yang, Longtan Li, Rui Yao et al.

Zheyong Piao, Tao Peng, Tao Meng et al.

Zhiwei SONG, Xinbo HUANG, Chao JI et al.

The transmission lines are complex in distribution and it is difficult to effectively detect their faults. Among them, the connecting fittings are susceptible to corrosion and other faults due to their long exposure to complex environments. Aiming at the problem that the transmission line connection fitting components are varied in scale and have poor accuracy in detecting their corrosion faults, a detection method is proposed for transmission line connection fittings and their corrosion faults based on dual attention embedding reconstruction and Swin Transformer, i.e., PCSA-YOLOv7 Former. The experimental results show that the proposed method is superior to 12 existing state-of-the-art object detection algorithms in comprehensive detection performance of the constructed TLCF dataset, with the mAP0.5 of the test set reaching 94.9 %. Compared with the baseline model YOLOv7, the proposed method improves the indexes F1 and mAP0.5 by 2.6 percentage points and 2.2 percentage points, respectively, indicating that the proposed method can more comprehensively understand the multi-scale semantic information in the images of transmission line connection fittings and learn their subtle details that are difficult to distinguish.

WANG Xiangyu, CHEN Wuhui, GUO Xiaolong et al.

With the development and evolution of the information revolution, promoting the integration of a new generation of digital technology with traditional power generation system, and promoting the digital construction of power generation systems is an important way to support energy transformation and digital grid construction. Based on the digital business needs of power generation system, this paper summarized the business needs of data in various scenarios such as the full life cycle management, intelligent operation and maintenance, and intelligent operation. The architecture of power generation system was expounded from the aspects of network structure and digital technology architecture. The key technologies and applications in the process of digitalization of power generation system were sorted out. Finally, the problems that need to be solved in the process of digitalization of power generation system were discussed.

Dinanath Prasad, Narendra Kumar, Rakhi Sharma et al.

Abstract Here, stochastic‐gradient‐based adaptive control algorithms have been discussed and employed for power quality enhancement in a Photovoltaics (PV) integrated distribution system. Least mean square (LMS), least mean fourth (LMF), sign‐error LMS, and ε‐normalised LMS (ε‐NLMS) have been implemented as control algorithms for the estimation of fundamental load current. The performances of these adaptive algorithms are compared under steady‐state and dynamic conditions under the non‐linear load conditions in a closed‐loop three‐phase system. The main aim of implementing these algorithms is reactive power compensation, power quality enhancement, and load balancing in a single‐stage three‐phase grid‐tied PV system. The hysteresis current control (HCC) technique is used to generate switching pulses for the three‐phase Distribution Static Power Compensator (DSTATCOM). An MPPT is also employed to ensure maximum power delivery from the solar PV array. PV integrated three‐phase single‐stage distribution system with adaptive control algorithms is implemented in MATLAB/Simulink environment as well as in experimental environment to achieve the goals per standard IEEE‐519.

Hui WANG, Yi CAO, Ning LUO et al.

This paper proposes a three-terminals soft open point (SOP) operation control mode switching technology under the multi-feeder faults. Firstly, combined with the inner and outer loop structures of control mode of three-terminals SOP, a control mode switching strategy with improved control logic is proposed. Secondly, in order to realize the smooth transition between SOP working modes under multiple feeder faults, a control mode switching process suitable for three-terminals SOP under multiple feeder faults is proposed. Then, by adopting the phase angle pre-synchronization strategy, the smoothness of the phase angle when the power-loss feeder is connected to the grid is ensured. Thirdly, the phase angle pre-synchronization strategy is adopted to ensure the smoothness of the phase angle when the power-loss feeder is connected to the grid. Finally, A power distribution system model with three-terminals SOP is built for simulation. The simulation results show that the proposed operation control mode switching technology can reduce the maximum voltage fluctuation on the DC side, and the voltage and phase angle of each port can transition smoothly.

Seokheun Choi

Biofuel cells have been in the spotlight for the past century because of their potential and promise as a unique platform for sustainable energy harvesting from the human body and the environment. Because biofuel cells are typically developed in a small platform serving as a primary battery with limited fuel or as a rechargeable battery with repeated refueling, they have been interchangeably named biobatteries. Despite continuous advancements and creative proof-of-concept, however, the technique has been mired in its infancy for the past 100 years, which has provoked increasing doubts about its commercial viability. Low performance, instability, difficulties in operation, and unreliable and inconsistent power generation question the sustainable development of biofuel cells. However, the advancement in bioelectrocatalysis revolutionizes the electricity-producing capability of biofuel cells, promising an attractive, practical technique for specific applications. This perspective article will identify the misconceptions about biofuel cells that have led us in the wrong development direction and revisit their potential applications that can be realizable soon. Then, it will discuss the critical challenges that need to be immediately addressed for the commercialization of the selected applications. Finally, potential solutions will be provided. The article is intended to inspire the community so that fruitful commercial products can be developed soon.

Wei Yu, Yan Zheng, Yongqiang Zhang

With the enhancement of environmental awareness, China has put forward new carbon peak and carbon neutrality targets. Electric vehicles can effectively reduce carbon emissions in the use stage, and some retired power batteries can also be used in echelon, so as to replace the production and use of new batteries. How to calculate the reduction of carbon emission by the echelon utilization of retired power batteries in energy storage power stations is a problem worthy of attention. This research proposes a specific analysis process, to analyze how to select the appropriate battery type and capacity margin. Taking the BYD power battery as an example, in line with the different battery system structures of new batteries and retired batteries used in energy storage power stations, emissions at various stages in different life cycles were calculated; following this in carbon emission, reduction, by the echelon utilization of the retired power battery, was obtained. Finally, the overall carbon emissions that might be reduced by echelon utilization in the future were calculated according to the BYD’s battery loading volume and China’s total power battery loading volume in 2021. This research provides a quantitative analysis idea for the carbon emission reduction of power battery echelon utilization. Using this method could improve the process of echelon utilization, optimize the supply chain of power batteries, drive the development of the new-energy vehicle industry, and explore new business models, so as to achieve the environmental protection goal of carbon neutrality.

Ehtisham Wahid, Ayaz Ahmad, Wilayat Khan et al.

Xiaoliang Zhang, Yimu Zhang, Yue Zhao et al.

Neither the separate skyhook damping nor the skyhook inertance control strategy can adapt to the variations of both road and load conditions simultaneously. To address this issue, this work proposed a novel ideal multi-hook system by combining the skyhook inerter and hybrid damper, with both of their coefficients optimized. The proposed system can achieve road holding without sacrificing ride comfort. Depending on whether the inerter and damper were adjusted independently or together, this ideal multi-hook was realized semi-actively in two different control models with three different control strategies, i.e., independent, inertance-based and damping-based control. The effects of these strategies were compared and analyzed. The simulation results show that compared with passive suspension, the root mean square value of body acceleration of the three kinds of multi-hook suspension decreases by more than 40% under different loads and by more than 28% on the roads of Classes A, B and C. Compared with the skyhook damping suspension, the dynamic wheel load of the multi-hook suspensions is reduced by more than 27.5%, proving that the semi-active suspension system with multi-hook control guarantees handling stability under various road and load conditions while ensuring ride comfort.

Wei LI, Tingfang YANG, Lei ZHANG et al.

In order to reduce the workload of the operation and maintenance of distribution line arresters, this paper designs a frequency-dividing disconnector using double sphere gaps based on the inverse time principle, which can reliably shunt high and low frequency current. The disconnector can be separated automatically and reliably while the insulation of the arrester is damaged, and the fault section can be found. The disconnector realizes the mechanism of frequency division of leakage current by using inductance and large sphere gaps in parallel. Under the impulse or high frequency, the leakage currents flow through the big sphere gap and the disconnector would not act. While under the power or low frequency, the leakage currents flow through the inductor. When the current takes value from 40 mA to 0.5 A, resistance heating action would be utilized. When the current is larger than 0.5 A, the small sphere gap breakdown action would be adopted, which avoids the mal-operation of disconnector due to burned out resistance. In these two cases, the greater the leakage current, the faster the disconnector operates. Through the ATP model simulation, the parameters of the inductance and the operating characteristics of the large gap can be determined. The numerical simulation and experimental results show that the disconnector can operate reliably when the insulation of the arrester is damaged.

Jizhe Dong, Yuanhan Li, Yu Lu et al.

Abstract To solve the unit commitment (UC) problems with efficient mixed‐integer linear programming solvers, the quadratic cost functions (QCFs) of thermal units are always approximated to piecewise linear (PWL) functions. This study examines the accuracies of different approximation methods for piecewise linearizing the QCFs of units in UC problems. We use five piecewise linearization methods—evenly spaced PWL interpolation, evenly spaced PWL tangent, evenly spaced PWL–ɛmax/2 shifted interpolation, tighter PWL interpolation, and evenly spaced PWL least‐squares fit—to approximate the QCFs of units. The authors first perform a series of reproductivity studies to verify the program. Then, numerical tests are conducted using different methods on the systems with 10, 100, and 800 units. The results show that different approximation methods lead to considerable differences in operating costs and the tighter PWL interpolation, compared with the other methods, is preferred in terms of approximation accuracy.

Steffen Oswald

Li-based batteries are a key element in reaching a sustainable energy economy in the near future. The understanding of the very complex electrochemical processes is necessary for the optimization of their performance. X-ray photoelectron spectroscopy (XPS) is an accepted method used to improve understanding around the chemical processes at the electrode surfaces. Nevertheless, its application is limited because the surfaces under investigation are mostly rough and inhomogeneous. Local elemental analysis, such as Auger electron spectroscopy (AES), could assist XPS to gain more insight into the chemical processes at the surfaces. In this paper, some challenges in using electron spectroscopy are discussed, such as binding energy (BE) referencing for the quantitative study of chemical shifts, gas atmospheric influences, or beam damage (including both AE and XP spectroscopy). Carefully prepared and surface-modified metallic lithium material is used as model surface, considering that Li is the key element for most battery applications.

T. G. Galieva, D. A. Ivanov, M. F. Sadykov et al.

THE PURPOSE. Development of diagnostic methods for high-voltage insulators in operation based on continuous recording of electromagnetic radiation. Hardware and software implementation of the device based on this technique. Carrying out experimental researches. METHODS. Received signal strength indicator measuring method of electromagnetic signals and method of determining the attenuation of electromagnetic radiation in space were used. RESULTS. The article describes relevance of the topic, considers various physical methods for registering partial discharges (PD) and their localization. Studies of the average signal level of defective and non-defective high-voltage insulators on load operation (10-15 kV) were carried out using the laboratory stand. An experiment was carried out to determine the space attenuation of a local signal from the PD. CONCLUSION. A technique for diagnosing high-voltage insulators during operation has been developed. This technique is based on continuous monitoring of electromagnetic radiation from partial discharges. Method for diagnosing high-voltage insulators makes it possible to monitor the insulation condition remotely and continuously.

Yury A. Secretarev, Tatyana V. Myateg, Tatyana E. Baldakova

Yaping Deng, Xinghua Liu, Rong Jia et al.

Accurate sag source location and precise sag type recognition are both essential to verifying the responsible party for the sag and taking countermeasures to improve power quality. In this paper, an attention-based independently recurrent neural network (IndRNN) for sag source location and sag type recognition in sparsely monitored power system is proposed. Specially, the given inputs are voltage waveforms collected by limited meters in sparsely monitored power system, and the desired outputs simultaneously contain the following information: the located lines where sag occurs; the corresponding sag types, including motor starting, transformer energizing and short circuit; and the fault phase for short circuit. In essence, the responsibility of the proposed method is to automatically establish a nonlinear function that relates the given inputs to the desired outputs with categorization labels as few as possible. A favorable feature of the proposed method is that it can be realized without system parameters or models. The proposed method is validated by IEEE 30-bus system and a real 134-bus system. Experimental results demonstrate that the accuracy of sag source location is higher than 99% for all lines, and the accuracy of sag type recognition is also higher than 99% for various sag sources including motor starting, transformer energizing and 7 different types of short circuits. Furthermore, a comparison among different monitor placements for the proposed method is conducted, which illustrates that the observability of power networks should be ensured to achieve satisfactory performance.