Urban Substation Research Articles

Intelligent Positioning Algorithm for Urban Substation Personnel based on Wireless Sensor Networks

In order to solve the problem of accurate and low-cost location of substation personnel in digital cities, a substation personnel location system based on wireless sensor cloud computing network is proposed. ZigBee wireless sensor cloud computing network is introduced into the substation to improve the direct location algorithm of substation personnel, and a fuzzy reasoning algorithm is proposed. The algorithm takes the signal strength received by each reference node and the relative distance between the reference nodes as input. After fuzzy, fuzzy reasoning and deblurring, the reliability of the received signal strength of each reference node is obtained, and then three reference nodes with high reliability are selected for trilateral positioning calculation. The experimental results show that the positioning error after improvement is more stable than that before improvement, and the maximum error before improvement is 1.4115m. Practice has proved that the algorithm can significantly improve the positioning accuracy of substation personnel without adding any hardware and using fewer nodes.

An Identification Method for Ground Potential of Grounding Grid in Urban Substations Considering Metro Stray Current

An Identification Method for Ground Potential of Grounding Grid in Urban Substations Considering Metro Stray Current

A site selection framework for urban power substation at micro‐scale using spatial optimization strategy and geospatial big data

AbstractThe world is facing more energy crises due to extreme weather and the rapidly growing demand for electricity. Siting new substations and optimizing the location of existing ones are necessary to address the energy crisis. The current site selection lacks consideration of spatial and temporal heterogeneity in urban power demand, which results in unreasonable energy transfer and waste, leading to power outages in some areas. Aiming to maximize the grid coverage and transformer utilization, we propose a multi‐scene micro‐scale urban substation siting framework (UrbanPS): (1) The framework uses multi‐source big data and the machine learning model to estimate fine‐scale power consumption for different scenarios; (2) the region growing algorithm is used to divide the power supply area of substations; and the (3) location set coverage problem and genetic algorithm are introduced to optimize the substation location. The UrbanPS was used to perform siting optimization of 110 kV terminal substations in Pingxiang City, Jiangxi Province. Results show that the coverage and utilization rate of the optimization results under different power consumption scenarios are close to 99%. We also found that the power can be saved by dynamic regulation of substation operation.

Separation of Urban Substation Noise and Environmental Noise based on Independent Component Analysis

With the development of urbanization, substations have started to be established in urban areas where the population is concentrated. To realize effective control of the substation noise, accurate measurements of the noise inside the substation and the surrounding area are necessary. However, in an urban area, the background noise, such as traffic noise, causes the sampled signals to contain not only the substation noise but also the background noise, which decreases the measurement accuracy. Thus, separating the substation noise from the environmental background noise is necessary. An independent component analysis method is used to realize the separation of the substation noise from complex environmental noises. In this paper, two typical environmental noises are selected, and their characteristics and the urban substation noise are analyzed. Then, a separation method based on the independent component analysis is constructed for separating substation noise. Its accuracy is evaluated using measured mixed signals. The verification shows that the separated substation noise is very close to the original substation noise signal, which shows that the method can be used in practical substation noise control engineering applications.

Experimental study of the noise generated by urban high-voltage electrical substations

This work describes the results of sound pressure measurements carried out in the vicinity of ten high voltage electrical substations operating in areas of considerable urban density in the State of Rio de Janeiro. The work was motivated as a strategy to guide the proposition of an acoustic attenuation solution to meet the imposition of the Public Prosecutor's office, which interposed a civil action in the name of dissatisfied residents of the neighbourhood of one of the substations studied. Based on the acoustic limits imposed by the applicable environmental legislation, the study evaluated the acoustic noise level at different points in the neighbourhood of ten urban substations in the city of Rio de Janeiro, studying in depth the acoustic noise in the internal and external environments of the substation subject to the civil action brought. Although it is not possible to eliminate the acoustic noise generated by high voltage transformers since it results from the natural phenomenon of magnetostriction, which is intrinsic to the operation of any high-power electrical transformer, there are alternatives to mitigate the sound pressure level. As part of the strategy, the work recommends, as a first action, eliminating any tonal component associated with the acoustic noise, as its presence in the frequency spectrum causes discomfort to the human ear and penalizes measured levels by +5 dB. The work also shows that it is not trivial to discuss the impact of acoustic noise generated by substations installed in urban communities, whose acoustic noise commonly exceeds regulated limits. In conclusion, the work confirms that most electrical substations operate on the boundary line of the permissible noise limits.

Noise Annoyance Prediction of Urban Substation Based on Transfer Learning and Convolutional Neural Network

The noise pollution caused by urban substations is an increasingly serious problem, as is the issue of local residents being disturbed by substation noise. To accurately assess the degree of noise annoyance caused by substations to surrounding residents, we established a noise annoyance prediction model based on transfer learning and a convolution neural network. Using the model, we took the noise spectrum as the input, the subjective evaluation result as the target output, and the AlexNet network model with a modified output layer and corresponding parameters as the pre-training model. In a fixed learning rate and epoch setting, the influence of different mini-batch size values on the prediction accuracy of the model was compared and analyzed. The results showed that when the mini-batch size was set to 4, 8, 16, and 32, all the data sets had convergence after 90 iterations. The root mean square error (RMSE) of all validation sets was lower than 0.355, and the loss of all validation sets was lower than 0.067. As the mini-batch size increased, the RMSE, loss, and mean absolute error (MAE) of the verification set gradually increased, while the number of iterations and the training duration decreased gradually. In this test, a mini-batch size value of four was appropriate. The resultant convolutional neural network model showed high accuracy and robustness, and the error between the prediction result and the subjective evaluation result was between 2% and 7%. The model comprehensively reflects the objective metrics affecting subjective perception, and accurately describes the subjective perception of urban substation noise on human ears.

Sound Absorption Performance of Aluminum Silicate Fiber for Noise and Vibration Reduction of Distribution Transformer

In view of the low-frequency noise problem in urban substation, the sound absorption (SA) properties of aluminum silicate fibers (ASF) with different materials, unit weight, plate thickness and cavity thickness were tested in this paper. It was found that the high-purity ASF with larger unit weight, plate thickness and cavity thickness had larger low-frequency SA coefficient, which provided technical support for the development of new low-frequency noise reduction materials for substation.

Urban 110 kV indoor substation noise analysis and control schemes: A real case study

As an important node in urban city, power substation provides the clean energy to thousands of households, ensuring a stable and high quality of urban life. However, the influence of noise emission from substation is always underestimated. With the improvement of environmental consciousness, making the substations quietly hidden in urban cities becomes an urgent issue which should be thoroughly considered. A real case is presented in this paper to vividly reflect how such a comprehensive noise issue is faced and tackled through proper techniques and novel applications. Based on the low-frequency noise characteristics of 110 kV power transformers and the limited space features of indoor substation, integrated noise control schemes are proposed with consideration of low-noise design of ventilation and heat dissipation systems. Dynamic vibration absorber is firstly investigated and designed to minimize the vibration of transformer tank. After the practical implementation, the acoustic environment is reevaluated and the measurement results verified the noise control effect. Consequently, the acoustic environment quality within and out of substation is improved and the negative impact of urban substation is controlled.

Calculation and Analysis of DC Magnetic Bias Current of Urban Main Transformer under the Action of Stray Current

The stray current generated by subway running into the ground makes the main transformer in the urban area in a direct current (DC) bias state. First, the mathematical model of the metro stray current field is established and the Galerkin finite element method is applied to calculate the model. Then, the dynamic model of the stray current-induced geoelectric field under different working conditions is established by using ANSYS software, and the three-dimensional numerical simulation study of the stray current-induced geoelectric field of the subway is carried out. Finally, taking the Urumqi subway in Xinjiang as an example, the stray current-induced geoelectric field is calculated and simulated, and the correctness of the model is verified by comparing with the measured data of DC magnetic bias in the urban substation. The research can provide useful reference for the calculation and treatment of DC bias of the main transformer in the urban area under the action of stray current.

A parameter design method for multifrequency perfect sound-absorbing metasurface with critical coupled Helmholtz resonator

The low-frequency harmonic components of urban substation noise are easy to annoy the residents. Multi-frequency perfect sound-absorbing metasurface based on the Helmholtz resonator (HR) is an alternative solution to suppress the low-frequency harmonic noise. This paper proposes an efficient design method of structural parameter for the multi-frequency perfect sound-absorbing metasurface. Taking the perfect sound absorption at the target frequency as objective and the structural parameters of HR as optimization variables, the structural parameter optimization model of multi-frequency perfect sound-absorbing metasurface is established and solved by the sequential quadratic programming algorithm. The proposed design method effectively overcomes the deterioration of sound absorption performance caused by the combined design of multiple perfect sound absorption units. Utilizing the proposed method, we designed a multi-frequency perfect sound-absorbing metasurface to absorb the four harmonic components of an urban substation noise simultaneously. The finite element simulation results and the experimental results of the physical sample indicate that the designed multi-frequency perfect sound-absorbing metasurface can satisfy critical coupling to achieve perfect sound absorption at all target frequencies.

Annoyance evaluation of noise emitted by urban substation

In China, noise pollution from substations in urban areas is becoming more and more serious. An annoyance evaluation of the noise emitted by urban substations is presented. First, the subjective evaluation is conducted on the noise samples from urban substations via the semantic differential method. Subsequently, according to the typical characteristics of urban substation noise, 14 acoustical metrics are used to describe the noise samples for objective evaluation. Then the correlation analysis and regression analysis between the objective and subjective evaluation results are carried out. Finally, a regression model for urban substation noise evaluation is established. Practical application shows that the regression model can correctly predict the subjective annoyance of urban substation noise.

Optimal configuration of energy storage system in multi-station fusion mode

Multi-station fusion mode (MSF) generally includes energy storage system, data center and electric vehicle charging station. It can improve the utilization rate of land and power distribution resources of urban substations. This paper studies configuration of ESS in the MSF model, aiming at reducing total cost. Firstly, an AC-DC system of MSF model is established. Then, aiming at economy, the optimal configuration model of ESS is established. Finally, the effectiveness of the model is verified by a practical example, and the MATLAB toolbox YALMIP with the CPLEX solver is used to conduct the ESS planning.

Experimental Study on the Vibration Characteristics of Oil Tank Model of Oil-Immersed Transformer

The problem of vibration and noise of transformers in urban substations is more and more concerning to society. With a 110kV transformer substation as the research object, the oil tank model of the oil-immersed transformer is designed according to the principle of similitude. Through the modal test of the oil tank model, the vibration characteristics of a 110kV oil-immersed transformer model are obtained, which will help avoid the resonance frequency in the structure design of transformer oil tanks and provide measured data for the vibration and noise control design of transformers. Finally, the finite element model of transformer oil tanks is established, and the vibration characteristics of the oil tank are simulated, and consistent analysis results are obtained.

Substation Grounding Grid Diagnosis Applying Optimization Techniques Based on Measurements and Field Tests

Considering urban substations ground grid diagnosis, some real-physical constraints result in measurement process challenges: 1) limited length between electrodes used to measure the equivalent impedance of the grounding system; 2) to determine the current that flows from ground grid conductors to the earth; and 3) to determine the grid resistance. In this scenario, an adequate diagnosis of the safety offered by the ground grid under test when a ground fault occurs is not a trivial task. This article describes a methodology that allows a reliable diagnosis regarding the safety provided by a substation ground grid. The methodology is applied to the parameters obtained in performed field tests. The method has two steps. First, the fall-of-potential method with reduced distances between electrodes is used to determine the equivalent impedance of the grounding system. Then, the ground current is obtained. In both stages, optimization techniques are applied to the specific equations that govern the phenomenon under investigation. Comparative case studies considering real-life data illustrate the effectiveness of the method.

Analysis of Noise Environment and Noise Reduction Measures in Urban 110kV Indoor Substations

With the rapid development of society and economy, the public awareness of environmental protection has gradually increased, and urban substation noise has become an environmental issue of concern to residents. In order to study the current status of the noise environment of urban substations, to guide the management of substation noise and the construction of transmission and transformation projects, this article selects 50 110kV indoor substations as objects, and measures their boundary noise. By analyzing the characteristics of the noise source of the substation with excessive noise and various noise reduction measures, the noise reduction methods suitable for urban indoor substations are summarized.

Research on Vibration Characteristics of Urban Substation Building and Transformer

The problem of vibration of the buildings and transformers in the urban substation has becoming more and more socially concerned. The urban substation and its associated building are taken as the research object. the vibration tests and modal shapes of the building and each floor slab were carried out. The transformer vibration and its noise were transmitted with obvious attenuation in the structural floor slab. The vibration transmission into the lower floor slab was higher than that of into the higher one. The further away from the transformer room, the vibration characteristics are weak, and the attenuation is no longer significant. At last, the finite element model was established for the urban substation. The transformer and floor slab vibration went through the simulated analysis and the consistent analysis results were obtained.

Ventilation Optimization for Reduction of Indoor Air Temperature of Main Transformer Room in Urban Indoor Substation by the Variational Method

Urban indoor substations are widely used for electrical power distribution in urban networks. However, they have the problems of heat dissipation and ventilation in main transformer room, which not only influence the thermal behavior of main transformer, but also decrease the lifetime, reliability, and precision of other electronic equipment. In this contribution, we developed a new ventilation optimization method based on the variational method to solve the aforementioned problems. First, we applied the minimum average temperature of indoor air as the optimization objective combined with some constrains to establish a Lagrange function, and employed the variational method to deduce some optimized governing equations that the optimum indoor patterns should meet the minimum indoor air average temperature. Finally, a typical main transformer room model was taken as an example to demonstrate the applications of the newly developed ventilation optimization method. It was concluded that the inflowing fresh air needed to sweep more area of heating walls to take away more heat, and reduce the average temperature of indoor air. Furthermore, based on the optimized air velocity distribution, we redesigned the ventilation arrangements and reduced the indoor average temperature prominently (from 337.44 K to 314.82 K), which can provide the guidance to design the ventilation of main transformer room to improve the reliability of electronic equipment in main transformer room.

The influence of Urban Substation on Neighbouring Metal Grounding System

With the development of China’s social and economic development, there are more high voltage substations in city and urban area. In order to better study the influence of fault current of urban substations on the neighbouring buildings, the paper studies the conduction interference between the urban substation with neighbouring merchants and civil buildings. Based on importance parameter, the surface potential, the conduction interference level of the civil substation system is quantitatively analyzed with different soil structure parameters, interval distance and the size change of the neighbouring grounding system. The research results show that, when the urban substation takes fault, even if there is no direct electrical connection, the surrounding commercial buildings and grounding system will be subjected to conduction interference. If do not considering the security of these grounding systems, it is easy to cause security risks. The soil structure is different, the influence of conduction interference is also different. The higher the soil resistivity in the bottom layer, more fault current will be scattered through the top soil, the more obvious the influence of conduction interference. With the increase of the size and distance between the neighbouring grounding system, the conduction interference effect will be reduced. In the design and safety analysis of the substation grounding system in the urban area, the safety of the surrounding buildings of the civil buildings should be considered. The research results provide theoretical basis and engineering guidance for the design of the grounding system in the urban substation and the safety protection of the commercial buildings surrounding the substation.

A Study on Control Algorithm of Thyristor Dual Converter System for DC Electricity Supply of Urban Railway

Most of systems that supplying electric power to operate an electric train of an urban railway to supply power by converting AC into DC through trolly wire, there are two rectification methods to converting AC into DC, with diodes or thyristor. Rectification method using thyristor is composed by 12 pulse thyristor converter with forward and reverse connection. Forward connection thyristor converter supplies electric power to trolly wire as forward mode operation, Reverse connection thyristor converter returns surplus trolly wire voltage to AC top main when regenerative electric power occurs according to regenerative braking, which reduces 20% operating power of an electric train. Rectification method using thyristor is appropriate for an electric train of an urban railway for improving operation efficiency and reducing greenhouse gases. In this paper, propose a dual converter using thyristor system for an urban railway substations and a control algorithm, and the validity of the proposed control technique is verified by the fabrication and experiment of 10 kW scale reduction model.

城市户内变电站主变室大门对降噪效果的影响研究

城市户内变电站主变室大门对降噪效果的影响研究