Mathematical Modeling of Multiple Capacitor Coupled Substations (CCS) Impact on Transmission Lines and Approaches for Ferroresonance Suppression

Rural electrification remains a critical challenge in achieving equitable access to electricity, a cornerstone for poverty alleviation, economic growth, and improved living standards. Capacitor Coupled Substations (CCS) offer a promising solution for delivering cost-effective electricity to these underserved areas. However, the integration of multiple CCS units along a transmission network introduces complex interactions that can significantly impact voltage, current, and power flow. This study presents a detailed mathematical model to analyze the effects of varying distances and configurations of multiple CCS units on a transmission network, with a focus on voltage stability, power quality, and reactive power fluctuations. Furthermore, the research addresses the phenomenon of ferroresonance, a critical issue in networks with multiple CCS units, by developing and validating suppression strategies to ensure stable operation. Through simulation and practical testing, the study provides insights into optimizing CCS deployment, ultimately contributing to more reliable and efficient rural electrification solutions.

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.

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.

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.

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.

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.

Integrated Approach to the Formation of Service Areas for Urban Substations of Different Voltage

UPSS （urban power supply system） is a part of the region or the state power supply system. UPSS development is closely connected with region power supply system development as a whole. The decision of questions of long-term and middle-term planning of UPSS development occurs in the conditions of incompleteness and uncertainty of the initial information. Nevertheless in these conditions the acceptance of development strategy should be based on perspective electric loads of urban TS （transformer substations）. There are difficulties with a rational placement of substations in the city with the developed infrastructure. Such problem by theoretically grounded approach to rational formation of UPSS is solved. The hierarchical structure of the organizational construction, voltage levels and load densities is considered. The mathematical and geometrical modeling of service areas for transformer substations of different voltage is fulfilled. The method of graphic placement of transformer substations in the city territory for new substations at existing structure of networks is offered. The aim of the work is to present the new uniform approach which allows finding a rational decision for new substations＇ placement in cities with developed infrastructure on the beginning design stages in conditions of the information uncertainty. The calculation program Microsoft EXCEL and the graphic program AutoCAD are used for realization of method.

Requirements and Proposed Solutions for Future Smart Distribution Substations

This paper proposes a novel solution for the secondary system of a primary distribution substation. First an evaluation is made of the changes that are to be expected for distribution substations in the future. Distributed generation, electric vehicles and other active resources will change the behavior of the distribution network in a manner that will have a great deal of implications for distribution substations. The question is how the role of the distribution substations will change when the visions of smart grids become reality. The proposed solution consists of bay level protection and control IEDs forming the backbone of the secondar？, system. The functionality is complemented with a substation level Station Computer, providing value added and advanced functionality. In addition required communication and time synchronization methods are presented. A life cycle cost evaluation is also performed on the proposed solution, and it is compared with the current dominant concept based exclusively on bay level devices.

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.

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.

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.

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.

AHLNet:Adaptive Multihead Structure and Lightweight Feature Pyramid Network for Detection of Live Working in Substations

With the increasing demand for power in society,there is much live equipment in substations,and the safety and standardization of live working of workers are facing challenges.Aiming at these problems of scene complexity and object diversity in the real-time detection of the live working safety of substation workers,an adaptive multihead structure and lightweight feature pyramid-based network(AHLNet)is proposed in this study,which is based on YOLOV3.First,we take AH-Darknet53 as the backbone network of YOLOV3,which can introduce an adaptive multihead(AMH)structure,reduce the number of network parameters,and improve the feature extraction ability of the backbone network.Second,to reduce the number of convolution layers of the deeper feature map,a lightweight feature pyramid network(LFPN)is proposed,which can perform feature fusion in advance to alleviate the problem of feature imbalance and gradient disappearance.Finally,the proposed AHLNet is evaluated on the datasets of 16 categories of substation safety operation scenarios,and the average prediction accuracy MAP_(50)reaches 82.10%.Compared with YOLOV3,MAP_(50)is increased by 2.43%,and the number of parameters is 90 M,which is only 38%of the number of parameters of YOLOV3.In addition,the detection speed is basically the same as that of YOLOV3,which can meet the real-time and accurate detection requirements for the safe operation of substation staff.

Time Synchronization for Transmission Substations Using GPS and IEEE 1588

Time synchronization systems that utilize the global navigation satellite systems(GNSS)are widely used in the monitoring,control,and protection of transmission networks.They ensure that phasor measurement units(PMUs)can accurately monitor voltage phase angles,increase the accuracy of fault locators,enhance the capabilities of disturbance recorders,and allow differential feeder protection to use re-routable communication networks.However,concern about the reliability of GNSS receivers used in intelligent electronic devices(IEDs)have been reported;problems include mal-operations of differential protection,erroneous satellite timing/location messages,inappropriate installations,and blocking of satellite signals due to illegal use of GNSS jammers in vehicles.Utilities now require a timing system less dependent on the use of low cost GNSS receivers integrated into IEDs,but one that uses Grandmaster clocks,slave and transparent clocks,and an Ethernet communication network.The IEEE 1588-2008 synchronization protocol uses the Ethernet to disseminate a global time reference around a substation.A future substation will probably include duplicate 1588 grandmasters,each incorporating stable oscillators with GNSS and terrestrial receivers,in conjunction with a 1588 compliant Ethernet data network with slave and transparent clocks,and redundancy boxes for interfacing with IEDs.Although IEEE 1588 protocol is promising for future substation automation systems,its performance and impact has to be fully evaluated before it can be used in real substations.This paper describes how an IEEE 1588 time synchronization testbed is designed,constructed,and tested.Testing involves measuring the time offset when the Ethernet is heavily loaded with other traffic and the holdover capability of 1588 clocks.Additional delay introduced by IEEE 1588 traffic is also measured.As there is limited testing on GPS receivers within the power industry,this paper also uses the testbed to evaluate the steady state and transient behavior of GPS receivers.The results show a 1588 time synchronization system is accurate,secure,and ideally suited for protection and control applications,compared to a timing system merely based on GPS receivers.The information described in this paper should increase a utility’s confidence in applying IEEE 1588 timing in a real substation.

Mathematical Modeling and Control Algorithm Development for Bidirectional Power Flow in CCS-CNT System

As the demand for more efficient and adaptable power distribution systems intensifies, especially in rural areas, innovative solutions like the Capacitor-Coupled Substation with a Controllable Network Transformer (CCS-CNT) are becoming increasingly critical. Traditional power distribution networks, often limited by unidirectional flow capabilities and inflexibility, struggle to meet the complex demands of modern energy systems. The CCS-CNT system offers a transformative approach by enabling bidirectional power flow between high-voltage transmission lines and local distribution networks, a feature that is essential for integrating renewable energy sources and ensuring reliable electrification in underserved regions. This paper presents a detailed mathematical representation of power flow within the CCS-CNT system, emphasizing the control of both active and reactive power through the adjustment of voltage levels and phase angles. A control algorithm is developed to dynamically manage power flow, ensuring optimal performance by minimizing losses and maintaining voltage stability across the network. The proposed CCS-CNT system demonstrates significant potential in enhancing the efficiency and reliability of power distribution, making it particularly suited for rural electrification and other applications where traditional methods fall short. The findings underscore the system's capability to adapt to varying operational conditions, offering a robust solution for modern power distribution challenges.

Hierarchical protection control system of smart substations

This paper analyzes the problems of the relay protections and secondary circuits of traditional substations,and introduces the hierarchical protection and control system of smart substations based on the technologies like IEC 61850 Standard,electronic instrument transformer,process level network,and wide area optical fiber communication network,etc.The hierarchical protection and control system includes three levels:local area protection,substation area protection and control,and wide area protection and control.These three levels are combined to solve the problems of the relay protections in traditional substations,thus improving protection performance and control capability of the system.

A Hybrid Circuit Breaker Based on Current Commutation Approach for Multi-feeder DC Railway Substations

The paper presents an economic hybrid circuit breaker for limiting and interrupting the faults in DC railways substations. For fast fault current interruption, the hybrid breaker incorporates high speed mechanical contacts actuated by power semiconductor devices. Additionally, to avoid formation of electric arc, a commutation circuit is used to inject a counter current during fault interruption. In a real railway substation, each feeder is connected to the main DC bus through an expensive air magnetic DC circuit breaker and to an auxiliary DC bus through another expensive breaker. This leads to high cost especially in railway substation with multi feeders which are used to energize the vehicle transmission lines. In this paper, all DC breakers in DC railway substations are replaced by the suggested circuit breaker, which consists of a high speed mechanical contact with two semiconductor devices in each feeder and only one commutation circuit for injecting the counter current in all faulted feeders. The fault diagnosis is designed to detect the abnormal condition (current or voltage) in all feeders and direct the injected current from the commutation circuit to the faulted feeder only when the abnormal reaches a predetermine level. The suggested breaker is able to detect and interrupt any cascading of faults.

Efficient maintenance testing in digital substations based on IEC 61850 edition 2

Digital substations are mostly important in the future of the electric power industry which makes their testing a critical process to ensure the required reliability and security of the grid.The paper introduces the definition of a digital substation and efficient testing,as well as the requirements for isolation during testing.It later describes testing related features in IEC 61850 Edition 2 and testing methods that can be used in digital substations.Maintenance testing examples and testing tools requirements are also presented.And remote testing principles are described at the end of the paper.The proposed remote testing by controlling the test system in a remote substation from the convenience of the engineering office brings significant benefits by improving efficiency and safety,as well as reducing outage times.