Grid Construction Research Articles

Global maximum flow based time-domain simulation method for evaluating power system resilience

With climate change, extreme weather is occurring frequently, which can cause serious damage to energy supply systems. It is of great significance to study the performance of power transmission system under extreme weather for prevention and reinforcement before and after disasters. This paper proposes a time-domain simulation model for quantifying power system resilience under extreme typhoon scenario. Firstly, the power system resilience assessment method based on global maximum flow (GMF) is presented, which is applied to map the overall system operation performance via creating a network indicator while considering component fragility, system topology, and power flow. A specific resilience expression (RES) is proposed to describe percentage improvement of each component in the resilience metrics by considering the overall system performance. Secondly, power system vulnerability model and time-domain simulation methodology are established. The proposed method is demonstrated by four case studies using the IEEE-30 node test system under specific typhoon scenarios. From the GMF based RES index, the component repair strategy is formulated accordingly. The proposed restoration strategy, compared with the traditional expert strategy can effectively measure the resilience contribution of each component to the whole power system, and minimizes the power system performance losses due to extreme typhoon. The proposed approach quantitatively evaluates real-time system resilience to extreme typhoons, and it can also identify the system critical areas and assess the benefits of different resilience enhancement strategies. The resilience assessment framework can also be applied to other extreme scenarios and contribute to planning and construction of strong smart grid in the future.

Design and development of power data service platform based on multi dimension

Abstract With the acceleration of power grid modernization, the scale of power grid is expanding. Running operations are becoming increasingly complex. There is a great demand for the analysis and calculation of the operation status of the power grid, line transformation design, fault analysis and treatment, etc. At the same time, with the construction of modern power grids and the continuous development of the power industry, the security problems of power systems have become increasingly prominent. This paper introduced the background of the power data service platform and then conducted academic research and summary on the research and development and design of power data service platform and multidimensional power data service platform. Then it was summarized with the analysis of international journals of emerging power systems. After establishing the algorithm model, the spark platform algorithm framework various algorithms were proposed to provide a theoretical basis for the R&D (research and development) and design of the multidimensional power data service platform. Then it analyzed the factors related to the R&D and design of power data service platform. At the end of the article, the simulation experiment was carried out, and the experiment was summarized and discussed. The experimental results showed that the average value of the neural network on the three criteria is 78.03 %. Therefore, the stability rate, accuracy rate, and recall rate of such algorithms as neural network are excellent in the research and development and design of power data service platform.

Pre-Attention Mechanism and Convolutional Neural Network Based Multivariate Load Prediction for Demand Response

The construction of smart grids has greatly changed the power grid pattern and power supply structure. For the power system, reasonable power planning and demand response is necessary to ensure the stable operation of a society. Accurate load prediction is the basis for realizing demand response for the power system. This paper proposes a Pre-Attention-CNN-GRU model (PreAttCG) which combines a convolutional neural network (CNN) and gate recurrent unit (GRU) and applies the attention mechanism in front of the whole model. The PreAttCG model accepts historical load data and more than nine other factors (including temperature, wind speed, humidity, etc.) as input. The attention layer and CNN layer effectively extract the features and weights of each factor. Load forecasting is then performed by the prediction layer, which consists of a stacked GRU. The model is verified by industrial load data from a German dataset and a Chinese dataset from the real world. The results show that the PreAttCG model has better performance (3~5% improvement in MAPE) than both LSTM with only load input and LSTM with all factors. Additionally, the experiments also show that the attention mechanism can effectively extract the weights of relevant factors affecting the load data.

Optimisation analysis of distribution network planning based on the IVIF-AHP method

Abstract Distribution network planning is an important task in the process of power grid construction and development. Scientific and rational planning is the key factor for the economic construction and reliable operation of the power grid. Aiming at the difficulty in quantifying the weight of distribution network planning schemes, a comprehensive evaluation method of distribution network planning schemes based on the interval-valued intuitionistic fuzzy analytic hierarchy process method is proposed. First, a comprehensive evaluation index system is established from the four aspects of power supply, namely reliability, economy, power supply quality and safety of the distribution network. Then, a comprehensive evaluation method of electricity reliability optimised by entropy weight method is adopted by analytic hierarchy process, which considers both subjective situation and objective weighting. At the same time, the comprehensive weight of the aggregation of the criterion layer and the scheme layer is calculated. Finally, the link between the aggregation matrix and the index weights of the criterion layer is used to calculate the weights of the scheme layer so that they can be sorted out. The experimental results show that the effectiveness and feasibility of the planning and analysis indicators and evaluation methods of the method proposed in this paper are verified by a numerical example.

Research on Energy Extraction Devices Based on High-Voltage Line Monitoring Technology

With the construction and development of an intelligent power grid, the voltage level of transmission lines is constantly improved. The distribution of power grids is increasingly broad, the climate environment along the transmission lines is complicated, the safe and reliable operation of transmission lines is facing significant challenges, and the inspection and maintenance workload of transmission lines is also increasing. Currently, only 20% of the online monitoring devices of transmission lines installed by the State Grid can operate normally. Power failures cause the most. It can be seen that it is necessary to develop an efficient and reliable power supply to improve the reliability of online monitoring devices of transmission lines. In order to enable the transmission lines to operate independently without maintenance for a long time, now the power grid needs an energy harvesting device with good stability, high energy harvesting efficiency, and strong resistance.

Design of High-strength Material Non-dismantling Docking Assembly

The construction technology of tower erection by segments with the cranes on the basis of the docking assembly has been applied in multiple cities and provinces in China. The docking assembly reduces the number of hoisting times, and lowers the safety hazards. However, the docking assembly which is an independent structure and made of common materials currently needs to be installed on and dismantled from the tower for each use, and each component is heavy. To address the above problems, the high-strength material non-dismantling docking assembly is studied to develop a design scheme which reduces the weight and eliminates the installation and dismantling work of docking assembly. Its successful engineering application shows that the use of high-strength materials effectively reduces the weight of the docking assembly and the docking assembly developed is safe and reliable, which greatly improves the efficiency of tower erection and reduces labor intensity. The project study results provide a reference for the design of high-strength material non-dismantling docking assembly for other types of transmission towers in the construction of power grids.

Novel high-performance automatic removal method of interference points for point cloud data in coal mine roadway environment

ABSTRACT In coal mine roadway, the reconstruction model obtained by 3D laser scanning is interfered by internal point cloud including dust, spray, auxiliary transportation vehicles, personnel flow, and so on, which seriously impacts deformation monitoring based on it. However, most of the current denoising methods barely consider the working conditions of roadway. Thus, this paper developed an automatic removal method of interference points with high efficiency and accuracy in coal mine roadway. It is realized through the establishment and transformation of local coordinate system, construction of voxel grid, bidirectional projection and central axis extraction, and noise removal based on a stepping bounding box. Under different levels of random noise and obstacle point clouds, the method has good performance. Based on the experimental results carried out in an underground roadway, the proposed approach takes 10 s to remove the interference points with an accuracy of 96%, which verifies the feasibility and effectiveness of the method.

Fault Identification of Secondary Equipment in the Intelligent Substation

With the continuous expansion of the scale of the power system and the increasingly complex structure, the intelligent construction of the power grid continues to deepen and the construction scale of smart substations as the core part of the smart grid is also expanding. At present, higher requirements are put forward for the operation and maintenance of the secondary system of the smart substation. Therefore, the fault diagnosis of the secondary system of smart substations has become an important research direction for smart grid construction. This paper proposes a secondary system fault location method for smart substations. The method uses a search algorithm based on an adjacency list and skyline query to determine the fault area. This scheme is applicable when the fault information is complete or not. Compared with the method of using the neural network to directly locate the fault of the whole network components, the training scale of the neural network is reduced and the “uncritical” feature quantity is reduced for the fault location. It highlights the value of “key” feature quantities and effectively improves the accuracy of the fault location.

Research and Practice on Slope Monitoring of Power Grid Construction Based on IoT Technology

In order to solve the shortcomings of traditional slope monitoring technology in automation, timeliness, and intelligence, this paper studies a slope monitoring system for high slopes in power grid construction based on power Internet of Things technology with characteristics of comprehensive perception, reliable delivery, and convenient application. By applying high-precision sensors, the plane and elevation monitoring accuracy of the system can reach a millimeter level. The layout principle of digital slope monitoring sensors is summarized and proposed according to traditional slope monitoring data in a power grid construction project in order to solve the relationship between actual slope monitoring demand and equipment investment. The slope monitoring system is applied in the three-level slope of a pilot project, and this technology realizes real-time judgment, efficient data transmission, and processing, making the obtained slope stability information more comprehensive, dynamic, and reliable.

Power supply optimization method based on multivariate load peak-valley complementary characteristics

The power grid load shows a trend of diversified development. With the continuous increase of the power grid construction scale, it is very important to optimize the power supply of the distribution network and improve the utilization of assets and equipment by using the peak valley complementary characteristics of multiple loads. In this paper, the peak-valley fluctuation characteristics of load are classified and analyzed. Cluster analysis is used to study the load classification with stable peak-valley characteristics in the complex load composition. Based on the peak-peak superposition and peak-valley complementary characteristics of the classified load, and considering the load space dimension, the multi-load optimization combination method for the whole period and time segment is proposed, and verified by simulation.

영동권 실 계통 PMU 측정정보를 활용한 울진, 삼척 산불 시 SSR 위험성 검토

The role of the power grid in the power system is to transmit the power produced at the power generation sites to the demand sites without interruption. When a new power source plan is established, a new power grid plan is also established so that necessary power grid construction is carried out at an appropriate time. However, the construction of a new power grid is not easy due to the problem of location selection and economic reasons. For this reason, efforts have been made for a long time to find ways to increase the capacity of the grid to avoid the construction of the new grid. A typical one of them is a method of increasing power transmission capacity by compensating the series capacitive impedance of the power transmission network. Therefore, KEPCO, in response to the delay in the construction of a new power grid for the construction of a large-scale power generation complex in the Yeongdong area, it was decided to increase the power transmission capacity of the existing power grid through series capacitive impedance. However, there is a risk that such an increase in transmission capacity through impedance compensation may cause problems such as sub synchronus resonance (SSR). In case of SSR, occured when the resonance frequency of the impedance-compensated power grid coincides with the mechanical resonance frequency of the nearby generator, and if a mechanical burden is accumulated on the generator shaft, the shaft may break. For this reason, the power authorities reviewed the risk of SSR and installed thyristor controlled series capacitor (TCSC) based on the results to avoid dangerous frequency bands by adjusting the apparent impedance of the impedance-compensated transmission line. In this way, the risk of SSR was responded to through sufficient preparation for impedance compensation. However, in the case of wild fires in Uljin and Samcheok, which occurred in March 2022, a number of transmission lines were opened, and the network topology between the compensation line and the nearby generator approached the condition of SSR, increasing the risk of resonance. This paper analyzes the risk of actual SSR based on the system configuration during wildfires in Uljin and Samcheok and the system operation information obtained through the Phase Measurement Unit (PMU) located nearby sites.

Flexible and Low-Cost Emulation of Control Behaviors for Testing and Teaching of AC Microgrid

The fast development of distributed generations enables the microgrid a popular solution for the construction of the modern power grid, where the control behaviors of power electronics converters play a crucial role. Under this scenario, the emulation of microgrid control behaviors is becoming an emerging need for the testing and teaching of the AC microgrid. However, conventional approaches, such as the dynamic simulation test and the Power-Hardware-In-Loop, are still costly or bulky to flexibly recreate the correct characteristics of microgrid including different layers of controls and the interactions among multiple converters. The dynamic simulation test is bulky and costly to emulate various types of control behaviors since all physical components in the test system may need to be adjusted. The high cost of Power-Hardware-In-Loop is mainly caused by the high-performance real-time simulator and power amplifier. In this paper, a novel emulation system is proposed for the testing of the AC microgrid. A low-cost circuit configuration, which includes two face-to-face connected DC–AC converters and some passive loads, is introduced with the possibility of flexibly emulating most of the typical control schemes in an AC microgrid. In addition, a user interface for the real-time operation and measurement of the hardware platform is introduced on a host computer to further facilitate the testing process. Finally, various control schemes in microgrids, including the voltage control, current control, droop control, and secondary control, are validated in the experiment setup based on the proposed emulation approach.

Research on power gathering problem and power transmission strategy in Guangxi coastal area

the construction of power supply is affected by resource conditions, plant construction conditions, load distribution and power grid structure, which shows a trend of more and more centralized distribution.If the power supply is too concentrated, the short circuit current will be increased, the risk of system security and stability will be increased, and the regional power transmission channel will be insufficient.The key to solve these problems is to find a suitable power transmission strategy.On the basis of fully summarizing the typical structure of domestic power grid, this paper puts forward the construction strategy of group transmission and layered transmission, and applies it to the construction of clean energy transmission grid in Guangxi coastal areas.

Incidence and risk factors of acute mountain sickness in grid construction personnel working at plateau

Objective: To analyze the incidence and risk factors of acute mountain sickness (AMS) in grid construction personnel working at plateau. Methods: A total of 10 956 plateau construction personnel of Ali Network Project from January 1, 2019 to December 31, 2020 were included. Baseline information (including age, sex, body mass index, developmental and nutritional status, relevant clinical indicators, etc.) and follow-up data of AMS were obtained from the medical record of Ali Internet engineering staff medical station. The altitude of the residence place in early life and the working environment were obtained from the website (https://zh-cn.topographic-map.com/legal/). The incidences of overall AMS and its subgroups were calculated, and the Cox proportional hazards model was used to explore the risk factors for AMS. Results: The age of the participants was (36.1±10.5) years old at baseline, and 95.27% (10 438) of them were males. The follow-up time was (17.46±4.23) months. The altitude of the residence place in early-life and working environment were (1 959±937) m and (4 533±233) m, respectively. During the follow-up period, the incidence of AMS was 15.58% (1 707 cases), and the incidence for acute mountain sickness and high altitude pulmonary edema were 15.53% (1 702 cases) and 0.05% (5 cases), respectively. No high altitude cerebral edema patients were found. Cox proportional hazards model showed that the risk of AMS increased by 45% for every 100 m elevation in the altitude of working environment [HR (95%CI): 1.45 (1.41-1.51)]. The higher the altitude for the residence place in early-life, the lower the risk of AMS [HR (95%CI): 0.84 (0.80-0.88)]. Compared with the group with oxygen saturation during 90%-94%, the participants with oxygen saturation<75% [HR (95%CI): 1.67 (1.24-2.23)] at baseline was also associated with increased risk of AMS. Conclusions: The incidence of AMS is relatively low in grid construction workers working on plateau. The risk factors of AMS included higher working altitude, lower altitude of the residence place in early-life and oxygen saturation<75%.

Research on power trade potential and power balance between Lancang-Mekong countries and southern China under long-term operation simulation

In order to further promote the interconnection development and construction of the power grids between the Lancang-Mekong countries and Southern China region and facilitate multilateral energy interaction, an assessment mechanism of the power balance and power trade potential between the two areas under long-term operation simulation is proposed. The mechanism first analyzes the energy supply structure, energy use forms, cross-border transmission capacity, and multi-area power trade potential of the power grids of the Lancang-Mekong countries and Southern China. Secondly, a power and electricity optimization model considering the long-period operation characteristics of generating units and regional interconnection transmission constraints is constructed, which can optimize the solution of a typical time-series operation scenario of 8760 h a year and improve the accuracy of regional power trade potential analysis. The results show that the Lancang-Mekong countries and the southern region of China have a significant potential for power trading, and the construction of a unified power trading market is vital for promoting the optimal allocation of power resources, achieving power balance, increasing the proportion of energy consumption, and reducing the cost of electricity consumption.

How much should you worry about contaminant neutrons in spatially fractionated grid radiation therapy?

Neutron contamination in radiation therapy is of concern in treatment with high-energy photons (> 10 MV). With the development of new radiotherapy modalities such as spatially fractionated grid radiation therapy (SFGRT) or briefly grid radiotherapy, more studies are required to evaluate the risks associated with neutron contamination. In 15 MV SFGRT, high-Z materials such as lead and cerrobend are used as the block on the tray of linear accelerator (linac) which can probably increase the photoneutron production. On the other hand, the high-dose fractions (10-20 Gy) used in SFGRT can induce high neutron contamination. The current study was devoted to addressing these concerns via compression of neutron fluence (Φn) and ambient dose equivalent ([Formula: see text]) at the patient table and inside the maze between SFGRT and conventional fractionated radiation therapy (CFRT). The main components of the 15 MV Siemens Primus equipped with different grids and located inside a typical radiotherapy bunker were simulated by the MCNPX® Monte Carlo code. Evidence showed that the material used for grid construction does not significantly increase neutron contamination inside the maze. However, at the end of the maze, neutron contamination in SFGRT is significantly higher than in CFRT. In this regard, a delay time of 15 minutes after SFGRT is recommended for all radiotherapy staff before entering the maze. It can be also concluded that [Formula: see text] at the patient table is at least 10 times more pronounced than inside the maze. Therefore, the patient is more at risk of neutrons compared to the staff. The [Formula: see text] at the isocenter in SFGRT with grids made of lead and cerrobend was nearly equal to CFRT. Nevertheless, it was dramatically lower than in CFRT by 30% if the brass grid is used. Accordingly, SFGRT with the brass grid is recommended, from radiation protection aspects.

Theoretical and applied approaches to assessing the level of progressiveness and innovativeness of electric grid construction projects

The article presents the study of conceptual directions of modernization of electric grids and innovative developments in the energy sector including evolutionary and breakthrough innovation. The author analyses the state of Russia’s market of the electric power industry and studies the experience and efficiency of research and development activities of the largest energy company PJSC ROSSETI. The priorities of innovative development in achieving energy efficiency are identified. The author of the article justifies the necessity of introduction of variant design during the implementation of investment projects of electric grid construction. Complex economic and technical assessment of the level of innovativeness and progressiveness of the project solutions which takes into account the scale of the manifestation of the economic effect should become the basis for this approach. The optimality of the engineering, technological and design solutions about the facility or building depends on both the level of qualification and experience of the designers and the quality of the software products used. Moreover, variant or exploratory design causes the need for the formation of innovative thinking among both developers and customers. The result of inventive creativity requires further assessment of the level of progressiveness and commercial feasibility of the created product. The author suggests principal and sectoral groups of criteria which allow recognizing new products or technologies resulting from R&amp;D as progressive and/or innovative. The article also contains the analysis of the group of criteria characterizing the level of technical equipment of the developer company. On the other hand, both exploratory design of technological systems and variant construction design result in the prolongation of the term of performance of contractual works. In return, prolongation of the terms results in increasing the cost of implementing design solutions. The situation may be solved by creating an open library of uniform projects with innovative characteristics and implementation practice.

Research on the Guidance Mechanism for the Price Signal of Power Grid Connection Service

At present, the utilization hours of thermal power continue to decline, and renewable energy generation also has a serious socket phenomenon, so it is necessary to guide the construction of power side selection points through price signals, so as to promote the smooth integration of more power generation into the grid. This study focuses on the connection services provided by grid enterprises to power side and demand side, analyzes and summarizes the connection charging practices of different countries, designs a shallow connection cost recovery model according to energy strategy and the characteristics of supply and demand side in our country, and puts forward feasible suggestions for renewable energy generation connection charging, in order to promote the investment and construction of grid and the consumption of renewable energy.

Bayesian Framework Helps History Matching of Permian EOR Field With Data Uncertainty

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 200807, “Closing the Loop on a History Match for a Permian EOR Field With Relative Permeability Data Uncertainty,” by Usman Aslam, Emerson, and Jorge Burgos, SPE, and Craig Williams, Occidental Petroleum, et al. The paper has not been peer reviewed. _ Reservoir production forecasts are inherently uncertain because of the lack of quality data available to build predictive reservoir models. Traditionally, a best estimate for relative permeability data is assumed during the history-matching process despite significant uncertainty. Performing sensitivities around the best-estimate relative permeability case will cover only part of the uncertainty space. In the complete paper, the authors present an application of a Bayesian framework for uncertainty assessment and efficient history matching of a Permian carbon-dioxide (CO2) enhanced oil recovery field for reliable production forecasting. Field Details Regional and Structural Geology. The Central Basin Platform (CBP) is a positive tectonic feature that separates the Delaware and Midland sub-basins of the Permian. The study field is located on the northeastern end of the CBP, with the Permian (Guadalupian) -aged reservoir composed of San Andres Formation dolostone. The total thickness of the unit is approximately 1,500 ft, with the main reservoir within the middle 600 ft. Structural Framework. The area of interest features 270 wells that have a total depth in the San Andres formation or deeper. Of these, 234 have digital open- or cased-hole logs that were used to correlate formation tops. After reviewing all well logs, it became clear that, historically, the zones were primarily identifiable from porosity picks, which are more subjective than markers identified with gamma ray methods. A new sequence stratigraphic framework was developed based on core descriptions and outcrop analogs. This correlation framework was then extrapolated to well logs. After a grid of north/south and west/east cross sections was correlated across the field and a series of loop ties was made for quality-control purposes, structure and isopach maps were created for each zone. Reservoir Description. At the time of discovery, natural gas was trapped at the structural high point of the study field. Above the gas/oil interface is the gas cap. Below the gas was an oil accumulation, which extended to the producing oil/water contact (POWC). The POWC was defined by early drilling as the maximum depth where water-free oil was produced. The base of the transition zone is the top of the residual oil zone (ROZ); this reservoir interval extends to the free-water level and is an interval believed to have been waterflooded naturally. The ROZ is the target for CO2 injection. Grid Construction and Property Modeling. A full-field detailed 3D reservoir characterization was modeled at 50-ft × 50-ft grid increments and an approximate 2-ft average layer thickness. The reservoir model consists of 114,222,528 cells. A total of 235 wells in the unit area was correlated and used to constrain the structural framework of the model. Quantitative porosity log suites were available in 233 of the wells in the model area, which were used to create the full-field porosity property in the 3D model. The logs were normalized to the core data and upscaled.

The function of coefficients of added mass of water

The hydrodynamic effect of the water mass of the reservoir on the pressure face of the dam can be determined from the function of the coefficient of the added mass of water obtained in the Westergard solution. For an inclined pressure face, the design standards introduce a correction factor, which is recommended to be taken into account until the slope of the pressure face does not exceed 150; there are no such recommendations for earth dams, however, in the calculations of seismic resistance of earth dams, taking into account hydrodynamic water pressure is also important. Theoretically, the values of the coefficients of the added mass of water can be determined based on the numerical solution of the Laplace equation in the computational domain with given boundary conditions and the graphical-analytical construction of a hydrodynamic grid. Thus, in the MATLAB environment, computational schemes were built for different laying of the pressure head of the dam in the range from vertical to flat with laying 1:3, and orthogonal hydrodynamic grids were built, reflecting the solution of the Laplace equations concerning the functions of pressure and velocity potentials. For all problems, diagrams of the coefficients of the added mass of water are constructed, and they are compared with the Westergaard analytical solution. For practical use in the work, all solutions for constructing diagrams of the coefficients of the added mass of water are presented in the form of a nomogram.