Mitigation of Transients in Capacitor Coupled Substations Using Traditional RLC Filter Techniques

This article presents an extensive examination and modeling of Capacitor Coupled Substations (CCS), noting some of their inherent constraints. The underlying implementation of a CCS is to supply electricity directly from high-voltage (HV) transmission lines to low-voltage (LV) consumers through coupling capacitors and is said to be cost-effective as compared to conventional distribution networks. However, the functionality of such substations is susceptible to various transient phenomena, including ferroresonance and overvoltage occurrences. To address these challenges, the study uses simulations to evaluate the effectiveness of conventional resistor-inductor-capacitor (RLC) filter in mitigating hazardous overvoltage resulting from transients. The proposed methodology entails using standard RLC filter to suppress transients and its associated overvoltage risks. Through a series of MATLAB/Simulink simulations, the research emphasizes the practical effectiveness of this technique. The study examines the impact of transients under varied operational scenarios, including no-load switching conditions, temporary short-circuits, and load on/off events. The primary aim of the article is to assess the viability of using an established technology to manage system instabilities upon the energization of a CCS under no-load circumstances or in case of a short-circuit fault occurring on the primary side of the CCS distribution transformer. The findings underscore the effectiveness of conventional RLC filters in suppressing transients induced by the CCS no-load switching.

Experimental investigation and analytically modeling of hysteretic behavior of rigid bus-flexible connectors of 220 kV electrical substations

This paper describes the quasi-static testing and analytical modelling of the hysteretic behavior of aluminum alloy rigid bus-flexible connectors of 220 kV electrical substations.The main objective of the study is to experimentally investigate the hysteretic behavior of six different types of rigid bus-flexible connectors 220 kV electrical substations when subjected to cyclic loading.Another objective is to theoretically study the flexibility and effectiveness of a previously proposed analytical model in fitting the experimental hysteresis loops of the tested rigid bus-flexible connectors.The experimental investigation indicates that the tested rigid bus-flexible connectors exhibit highly asymmetric hysteresis behavior along with tension stiffening effect.The theoretical study demonstrates that the generalized Bouc-Wen model has high flexibility and is effective in fitting the experimental hysteresis resisting force-displacement curves of the six tested rigid bus-flexible connectors.

Maximum Inner Product Method for Extracting the Path-Loss Parameters in Primary Transformer Substations

In order to deploy short-range wireless communication devices in the primary transformer substation, a Maximum Inner Product(MIP) Method is proposed to extract the path-loss parameters in 110 kV and 220 kV primary transformer substations. The maximum inner product of the testing data is calculated to find out the loss index n and the standard deviation σ, and then the pathloss models can be set up. By comparing the MIP with Minimum Mean Square estimation(MMSE) and Cumulative Sum(CUSUM), MIP can match the measured values best. In order to apply the MIP path-loss model, under the initial signal to noise ratio(SNR) at 5 dB and 10 dB, a ZigBee simulation system is constructed to validate the situation that bit error rate(BER) varies with distance. And the ZigBee devices with 5 units are tested in a 220 kV primary transformer substation. The result of the test proves that the path-loss model is accurate.

An Algorithm for Optimal Firewall Placement in IEC61850 Substations

Recently, most electric power substations have adopted production control systems, such as SCADA systems, which communicate with field devices and remotely control processes from a computer screen. However, these systems together with protection measures and additional control actions (using protocol IEC61850) seem not to be enough to free substations of security attacks (e.g. virus, intruders, forgery or unauthorized data manipulation). This paper analyzes the main features of an electric power substation together with the aspects that might be significantly affected by cyber-attacks. The paper also presents the implementation of a specific security system (i.e. firewall-wise system) intended to protect a target distribution network.

Research on Distribution of Electromagnetic Environment around Substations and Optimization Layout of On-line Monitoring

The characteristics and distribution law of electromagnetic environment around substations with different levels of voltage were studied,and the main influencing factors were discussed. Meanwhile,a scheme for locating monitoring points suitable for an on-line monitoring system of electromagnetic environment was proposed.

A Maintenance Optimzation Policy for an Electric Power Distribution System: Case of the HV/MV Substations

Today, in the modern era, and under the pressure of rapid development around the kingdom regions, electric utilities are confronted with a myriad of challenges that include aging infrastructure, enhanced expectation of reliability, reduced cost, and coping effectively with uncertainties and changing regulation requirements. Indeed, for distribution systems, HV/MV substations represent a complex and critical physical asset that requires a careful evaluation of their maintenance practices aiming at more cost-effective tasks. The first concern of the electric power distribution company in Morocco is the optimization of the distribution network maintenance scheduling, to minimize system operating costs and ensure that the system is running most economically. There is significant pressure on power providers for greater system reliability and improvement of customer satisfaction, while similar emphasis is placed on cost reduction. These cost reductions focus on reducing operating and maintenance expenses, and minimizing investments in new plants and equipment. However, the present of the electricity distribution, influenced by a number of technical restrictions and strict regulatory requirements to meet, leads distribution utilities to search new ways of optimizing the maintenance management, make an effort to maximize profit by reducing their electricity supply and operation costs while maintaining their reliability, developing more effective activities, with lower costs. Furthermore, maximal HV/MV substation asset value and minimal maintenance cost are typical economic objectives of the electric utilities. The optimization of maintenance is one possible technique to reduce maintenance costs while improving reliability and utilities need to implement new strategies for more effective maintenance techniques and Asset Management (AM) methods programs to manage inspections and maintenance activities in order to control HV/MV substation equipment conditions. However, development of strategies to make sound decisions in order to effectively improve equipment and system reliability while meeting constraints such as a maintenance budget is a challenge. Finally, this paper describes the application of a new approach based Reliability Centered Maintenance (RCM) methodology to optimize maintenance resources and to the development of maintenance plan for HV/MV distribution substations. For this purpose, a case study was performed on the equipment of power distribution systems for the benefit of a holding company (ONEE Electricity Distribution) in Morocco. The present study was conducted in Oujda Exploitation Maintenance Service (OEXMS), in charge of operation and maintenance of distribution networks.

Study on the Three Dimension Attenuated Model and the Algorithm of Environmental Noise in Substations

为了准确计算变电站噪声对周边环境影响的大小，通过对噪声衰减理论和变电站环境特点的分析，建立了变电站仿真数学模型，并基于该模型提出了变电站三维空间噪声预测算法。噪声衰减计算中，最复杂的是求解几何衰减中菲涅耳数，而求解菲涅耳数的关键是求解绕射声的声程差，利用凸包算法求解变电站内多声源、多障碍等复杂场景的声程差问题。仿真计算结果与实测结果对比显示，该模型和算法能够准确预测变电站周边三维空间中任意位置的噪声大小，为开展变电站环境噪声预评价、新建变电站规划设计中噪声控制优化以及运行变电站噪声的工程治理方案优化等提供技术支持和理论依据。

Auxiliary-Service Smart Monitoring Solutions: A Study in High-Power Substations in Colombia

The present study assesses the possibility of implementing an auxiliary-service smart monitoring solution at power substations. The solution is intended to improve substation indices in terms of accident rates and undesired events that result from initial incidents associated to failure of the Direct Current systems in charge of supporting the operation of protection elements. In recent years in Colombia, substation fires have been reported, and auxiliary services have been identified as a potential initial cause of these unfortunate events. In fact, in Bogotá (Capital city of Colombia), in the last decade, incidents occurred at four high-power substations, and the potential failure cause was associated to the operation of auxiliary services, according to the criteria of experts in the electrical sector. The present study illustrates how a monitoring system substantially improves the lifecycle of battery banks in a three-year period (8% lifecycle improvement together with an increase in reliability of the system by allowing more time for failure identification). The estimated financial benefits reach 2 million US dollars and stem from reducing the frequency of explosions at substations by 11%. The technology in question is assessed and recommended based on the results of various experiments, where various monitoring methods are tested, also considering the operation and maintenance costs that constitute an appropriate lifecycle evaluation.

Fair hierarchical clustering of substations based on Gini coefficient

For the load modeling of a large power grid,the large number of substations covered by it must be segregated into several categories and,thereafter,a load model built for each type.To address the problem of skewed clustering tree in the classical hierarchical clustering method used for categorizing substations,a fair hierarchical clustering method is proposed in this paper.First,the fairness index is defined based on the Gini coefficient.Thereafter,a hierarchical clustering method is proposed based on the fairness index.Finally,the clustering results are evaluated using the contour coefficient and the t-SNE two-dimensional plane map.The substations clustering example of a real large power grid considered in this paper illustrates that the proposed fair hierarchical clustering method can effectively address the problem of the skewed clustering tree with high accuracy.

A Brief Introduction to Features of Equipment and operating Condition of 500 kV Transmission Lines and Substations in Northeast China Electric Power Network

This article introduces the features ofequipment and operating condition of 500kV transmission lines and substations inNortheast China Electric Power Networkfrom the operation Point of view. The operatingand technical levels of domestic equipment arethe focus of discussion in the article.

Research on Testing Technologies of Network System in Smart Substations

The network structures of smart substations and the characteristics of industrial Ethernet switches are analyzed.The testing technologies of network systems based on smart substations are specifically elaborated.A viewpoint is proposed that special testing policy&method of smart substation networks should be followed,so that the results can reveal the real network data exchange performance of the whole station.This view ensures the safety and stability of smart substations and lays a foundation for future upgrades and expansions.

Efficient Methodology for Design of Industrial Blast Resistant Electrical Substations and Control Buildings

This paper describes economical strategies to design blast resistant electrical substations and control buildings that are commonly used at industrial plants.Limited literature addressed design aspects for this class of buildings.Furthermore,little guidelines are available in practice to regulate this type of steel construction.The first part of the paper overviews the architectural and structural layouts of electrical buildings.Blast resistance requirements for occupied control buildings are also discussed.Simplified multiple degrees of freedom(MDOF)dynamic model is also illustrated that can be utilized for analysis of the blast resistant buildings.The economical aspects and cost savings resulting in using mobile blast resistant buildings are discussed.The article also highlights the engineering challenges that are encountered in design of mobile electrical facilities.The transportation procedure and design requirements are briefly described.Guidelines are proposed to calculate the center of mass of the building combined with interior equipment.The proposed design concept for electrical and control buildings is cost effective and can be implemented in industry to reduce projects cost.

Substation clustering based on improved KFCM algorithm with adaptive optimal clustering number selection

The premise and basis of load modeling are substation load composition inquiries and cluster analyses.However,the traditional kernel fuzzy C-means(KFCM)algorithm is limited by artificial clustering number selection and its convergence to local optimal solutions.To overcome these limitations,an improved KFCM algorithm with adaptive optimal clustering number selection is proposed in this paper.This algorithm optimizes the KFCM algorithm by combining the powerful global search ability of genetic algorithm and the robust local search ability of simulated annealing algorithm.The improved KFCM algorithm adaptively determines the ideal number of clusters using the clustering evaluation index ratio.Compared with the traditional KFCM algorithm,the enhanced KFCM algorithm has robust clustering and comprehensive abilities,enabling the efficient convergence to the global optimal solution.

Modeling and Simulation of a Transmission Line Response to a 400 kV/400V Capacitor Coupled Substation

The access to electricity in rural areas is extremely limited, but it is crucial for all citizens. The population in rural areas of sub-Saharan African (SSA) countries is generally low, making it economically unfeasible to implement traditional rural electrification (CRE) projects due to the high cost of establishing the necessary distribution infrastructure. To address this cost issue, one alternative technology for rural electrification (URE) that can be explored is the Capacitor Coupled Substation (CCS) technology. CCS is a cost-effective solution for supplying electricity to rural areas. The research is necessitated by the need to offer a cost-effective technology for supplying electricity to sparsely populated communities. This paper examines the impact on the transmission network when a 400 kV/400V CCS is connected to it. The system response when a CCS is connected to the network was modeled using MATLAB/Si-mulink. The results, based on the fixed load of 80 kW, showed negligible interference on the transmission line voltage. However, there was minor impact on the parameters downstream of the tapping point. These findings were further supported by introducing a fault condition to the CCS, which showed that interferences with the CCS could affect the overall stability of the transmission network downstream of the tapping node, similar to the behavior of an unstable load.

Intelligent Detection Method of Substation Environmental Targets Based on MD-Yolov7

The complex operating environment in substations, with different safety distances for live equipment, is a typical high-risk working area, and it is crucial to accurately identify the type of live equipment during automated operations. This paper investigates the detection of live equipment under complex backgrounds and noise disturbances, designs a method for expanding lightweight disturbance data by fitting Gaussian stretched positional information with recurrent neural networks and iterative optimization, and proposes an intelligent detection method for MD-Yolov7 substation environmental targets based on fused multilayer feature fusion (MLFF) and detection transformer (DETR). Subsequently, to verify the performance of the proposed method, an experimental test platform was built to carry out performance validation experiments. The results show that the proposed method has significantly improved the performance of the detection accuracy of live devices compared to the pairwise comparison algorithm, with an average mean accuracy (mAP) of 99.2%, which verifies the feasibility and accuracy of the proposed method and has a high application value.

基于双对数正态分布的电瓷型电气设备地震易损性研究

总结了110 kV和220 kV典型电气设备的地震易损性曲线研究成果,考虑不同研究成果的离散性,基于双对数正态分布给出了抗震能力中值、随机性和不确定性建议值。进一步开展220 kV变电站系统的抗震性能分析,定量评价了变电站的功能性。研究结果表明:双对数正态分布可以较好地反映电气设备地震易损性的离散性,尤其是模型、方法等原因导致的不确定性。变电站系统的抗震能力低于电气设备的抗震能力,设计中应采取措施提高变电站的冗余性。变电站系统抗震性能与电气设备抗震能力中值正相关,与随机性和不确定性呈负相关。

10kV箱变改造为发电机转子护环感应加热电源的研究与应用

在某核电站汽轮发电机转子首次检修和绕组发生绝缘缺陷时,需要采用感应加热法拆除转子护环进行检查与处理。本文结合电站实际情况及护环拆装需求,经过分析与计算,按照最优的单绕组供电方案将工程建设期退役的10kV箱式变电站改造成拆装发电机转子护环所需的感应加热电源,并在两台百万千瓦级汽轮发电机的首次大修和转子绝缘缺陷处理中实现成功应用,有效保障了核电站发电机大修工期,节约了大修成本。

变电系统运行状态感知与协调调度实验虚拟仿真的设计与实践

为有效培养学生在变电系统实验中的自主探究能力和工程创新能力,设计了变电系统运行状态感知与协调调度实验虚拟仿真系统。分析了实验虚拟仿真教学的必要性,构建了以“两性一度”为原则的实验仿真内容,提出了以目标成果为导向的实验教学评估机制,并设计了与实验内容相适应的虚拟仿真教学方法。实践表明,该实验虚拟仿真突破了实验抽象、危险且单一的教学模式,有助于培养学生发现问题、解决问题的主观能动性和分析思考能力,解决实践教学中目标、行动与评价脱节问题,有利于提升电气信息专业的实验教学质量。

变电站铅酸电池的失效及综合修复

铅酸电池是直流(DC)系统的重要储能设备,对变电站的安全稳定运行至关重要。站用铅酸电池寿命普遍低于理论寿命,大量电池的提前失效给电网企业带来巨大的经济和环境压力。针对变电站铅酸电池的特殊运行环境,对失效电池复杂的失效模式进行分析。采用化学和物理相结合的技术手段,针对性地选择合适的活化剂,同时使用“大电流-恒流-恒压”的充电方式,达到修复活化失效铅酸电池的目的,修复后的铅酸电池容量可达额定容量的80%以上。