Reliability Of Electric Power System Research Articles

The Value of CSP with Thermal Energy Storage in Providing Grid Stability

CSP plants both with and without thermal energy storage are unique renewable resources that provide clean electric power and a range of operational capabilities to support continued reliability of electric power systems. Utilizing stored thermal energy storage to operate a conventional synchronous generator, CSP plants with thermal energy storage can support power and provide ancillary services including voltage support, frequency response, regulation and spinning reserves, and ramping serves – services that would otherwise be provided, at least in part, by conventional fossil-fuel generation.By being available during peak demand in sunlight hours and providing the capability to shift energy to other hours, the addition of thermal energy storage to CSP plants improves their contribution to resource adequacy, or capacity requirements, especially as solar penetration increases. This makes CSP an ideal complement to support greater adaption of intermittent resources such as wind and PV.To make procurement decisions that include a balance of both solar PV and CSP, utilities need to see reasonable estimates of quantifiable economic benefits. In simulations of the California power system, recent studies by the Lawrence Berkeley National Labs (LBNL) found that the comparative value of CSP with storage increases as the amount of solar on the grid increases. If CSP with six hours of storage and PV with no storage were each providing five percent of the grid's power, CSP power would have an additional value of $19/MWh (1.9¢/kWh). At grid penetrations of 10 percent each, CSP power would be worth an additional $35/MWh (3.5¢/kWh). The added value results from a calculation of grid integration costs and market benefits. The author will outline how CSP with storage provides grid stability and its corresponding value to utilities.

Análisis de Estabilidad de Pequeña Señal Utilizando Mediciones Sincrofasoriales PMU

Con el acelerado crecimiento de la demanda en los últimos años, las transferencias de potencia a largas distancias entre diferentes empresas de energía han ido aumentando constantemente, razón por la cual la seguridad y confiabilidad de los Sistemas Eléctricos de Potencia -SEP- pueden verse seriamente comprometidas, especialmente por el alto riesgo de violación de los límites de seguridad del sistema eléctrico.
 Uno de los desarrollos más importantes e innovadores en el área de monitoreo y control de los SEP está orientado a las Unidades de Medición Fasorial (PMU). Esta tecnología permite realizar el monitoreo de oscilaciones de baja frecuencia del Sistema Nacional Interconectado -S.N.I.- en tiempo real.
 En el presente trabajo se utiliza la información de las PMU’s, las cuales se encuentran estratégicamente ubicadas en el SNI, para realizar el análisis oscilatorio de baja frecuencia, mediante la aplicación de una de las técnicas de estimación modal conocida como Análisis Prony.

Primary energy congestion of power systems

Primary energy has the potential to bring challenges to the reliability, economic, and eco-friendliness of global electric power systems. The concept of electric power security are proposed, including many factors that are not considered in power system reliability analysis, such as coal supply for power system, fuel price for elec- tricity power market, carbon emissions of power genera- tion, and so on. It is broader than power system reliability and security, which means that providing energy in the form of reliable, economical, and eco-friendly electric power. Following an account of existing blackout defence methods and systems, the processes of transforming vari- ous kinds of primary energy into electric power and the interactions between them are described, particularly with regard to flows of energy, capital, and information. Factors that limit the liquidity of these flows are defined as ''gen- eralized congestion'', and the challenges presented by primary energy are named ''primary energy congestion''. China's dilemma on coal supply for power generation is presented in some detail as an example of primary energy congestion. To cope with impacts of the primary energy on electric power systems, an idea is introduced to extend the scope of existing coordinated blackout defence systems to account for primary energy, which would lead to an integrated tool to provide decision support to power system operators accounting for primary energy congestion.

Beta (phase constant) compensation for flat voltage profile in a transmission line

The reliability of the bulk electric power systems is not only dependent on the generation but also on the transmission system. In long lines, the voltage along the transmission line varies with the loading conditions. Proper reactive power compensation helps to maintain the voltage along the line within acceptable limits. This paper proposes a compensation method to adjust the phase constant of the transmission line in order to obtain a flat voltage profile along the line. Case studies conducted on a long transmission line are presented.

The Reliability Evaluation of Power System Based on Uncertain Linguistic Information

Electric power system reliability evaluation depends on reasonable target setting and calculation. This article mainly analyses the new index of power system reliability assessment in the electricity market environment, and on the basis of this, introduces the application of uncertain linguistic information in the ceremony system reliability evaluation, representing original parameters with uncertain number, and random processing fault condition happened and transfer events and process.

Correlation of dielectric model parameters with experimental results based on PDC, RV and loss factor measurements for high voltage capacitors

To improve the reliability and quality of electric power systems, preventive diagnosis and regular maintenance of high voltage capacitors are required. Dielectric response measurements in both time domain and frequency domain are potential tools for assessing the condition of dielectric of high voltage capacitors. Modern measurements in time domain include polarisation and depolarisation current (PDC) and recovery voltage (RV) measurements, whereas frequency domain measurements include dielectric dissipation factor (DDF) measurements. To understand the physical behaviour due to the effect of moisture and aging, a detailed analysis of dielectric test results is required. In this paper, a detailed equivalent circuit model of the insulation system in high voltage capacitors has been given. The values of the parameter of the circuit model have been calculated from the dielectric test results. Correlation between the physical condition of the insulation and the equivalent model parameters are also presented in this paper.

Innovative Technologies for Operation and Emergency Control in Electric Power Systems of Russia

Operation and emergency control including dispatching and automatic control procedures and devices that provide reliability and survivability of electric power system plays an important role in the control of operating conditions in the Unified Energy System (UES) of Russia. This control system is rather developed and even now has elements of the Smart Grid ideology due to its current adaptability, optimality and intelligence. The authors present current operation and emergency control system in the UES of Russia and suggest a modern approach to monitoring, forecasting and control. Some advanced methods and tools for development of dispatching and automatic control in electric power system are discussed. This work was supported by the grant of Leading Scientific School of the Russian Federation #1507.2012.8.

Application of Flower‐Like ZnO Nanorods Gas Sensor Detecting SF6 Decomposition Products

Gas insulated switchgear (GIS) is an important electric power equipment in a substation, and its running state has a significant relationship with stability, security, and reliability of the whole electric power system. Detecting and analyzing the decomposition byproducts of sulfur hexafluoride gas (SF6) is an effective method for GIS state assessment and fault diagnosis. This paper proposes a novel gas sensor based on flower‐like ZnO nanorods to detect typical SF6 decompositions. Flower‐like ZnO nanoparticles were synthesized via a simple hydrothermal method and characterized by X‐ray powder diffraction and field‐emission scanning electron microscopy, respectively. The gas sensor was fabricated with a planar‐type structure and applied to detect SF6 decomposition products. It shows excellent sensing properties to SO2, SOF2, and SO2F2 with rapid response and recovery time and long‐term stability and repeatability. Moreover, the sensor shows a remarkable discrimination among SO2, SOF2, and SO2F2 with high linearity, which makes the prepared sensor a good candidate and a wide application prospect detecting SF6 decomposition products in the future.

Detailed reliability assessment of composite power systems considering load variation and weather conditions using the Bayesian network

SUMMARY Adverse weather has considerable effects on reliability of electric power systems. On the other hand, using the Bayesian networks (BN) in reliability studies provides the possibility of analyzing different factors, especially the importance evaluation of system components. In this paper, a novel approach is presented to consider the weather conditions and load level variation in construction and implementation of the BN associated with the composite power systems. In this approach, the geographical division model is used to model weather conditions in various regions of the given power system and also different sections of overhead transmission lines. The obtained BN provides an effective framework for comprehensive reliability study of composite power systems. Copyright © 2012 John Wiley & Sons, Ltd.

Model for Power Shortage Estimation in Electric Power Systems

This paper addresses the model for power shortage estimation in electric power systems. The model’s main component of methodology for analysis of electric power system (EPS) reliability that has been developed at the Energy Systems Institute, Siberian Branch of Russian Academy Sciences. The methodology is based on the Monte-Carlo method. Quality and implementation time of reliability analysis depend on realization of the model. The model is implemented in the computational software for electric power systems reliability analysis. The history of evolution of the model for power shortage estimation and mathematical properties of the model are discussed. The results of the state-of-the-art studies of the model for power shortage estimation in EPS are presented. The model for power shortage estimation in EPS with quadratic power losses in power lines is considered. Algorithms of the interior point method with quadratic approximations of constraints applied for realization of the model are discussed. Results of experimental studies of the algorithms are presented.

New reliability coefficients of MV/LV transformer/distribution substation and its components

This paper introduces the possibility of application of u- and k-coefficient to operational reliability analysis of MV/LV transformer/distribution substations. The failure duration index was shown to have specific constraints in cost-related assessments of electric power system reliability. A direct correlation was assumed to exist between the failure duration and the actual emergency shutdown time, which can be shown with the u- and k-coefficients. The value of both indices has been determined on the basis of empirical data collected at two major power plants in Poland throughout the period of 10years.

분산전원이 도입된 배전계통의 보호협조 해석방법

기존의 수지상 배전계통은 사고 등에 대한 설비보호 및 전력공급 신뢰도 향상을 위하여 과전류보호협조방식을 채택하고 있다. 국내 배전계통의 경우, 그 보호방식 협조체계는 배전용변전소 동일 변압기 동일 모선에서 다수의 배전선이 각각 CB(변전소 차단기)를 통하여 인출되어 각 배전선로 이하에서 사고발생시 고장전류를 검출하여 해당 CB를 차단하도록 되어있다. 그러나, 이와 같은 보호방식을 채용하고 있는 배전계통에 분산전원이 도입될 경우 변전소 인출차단기의 차단용량은 영향을 받게 되므로 충분한 검토가 필요하다. 본 논문에서는 분산전원 도입시, 국내 배전용 변전소의 인출차단기에 대한 차단용량을 초과하지 않는 보호협조방법을 제시하고, 이를 PSCAD-EMTDC 계통해석 S/W Tool에 의하여 모의하여 검증하였다. In most of radial distribution systems, the overcurrent protection coordination is adopted for the protection of apparatus and the improvement of electrical power system reliability. The protection coordination structure in distribution substation is composed of several circuit breakers(CB) with distribution lines originating from one substation bus under one transformer, which trip for their fault current. But sufficient analysis is necessary for the capacity of CB's in distribution systems with several distribution generations(DG). In this paper, a protection coordination method not to exceed the traditional capacity of CB's was proposed and certified through simulation by the PSCAD-EMTDC S/W.

Measures to reduce surge voltages on low-voltage circuits in substations

In order to improve the reliability of electric power systems, it is important to reduce malfunctions of relays or faults of low-voltage control circuits in substations due to switching and lightning surge. However, it is not sufficient to study the intrusion of surges into low-voltage control circuits. We studied the terminal voltage of the control panel and analyzed the intrusion route of surges in substations. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(1): 1–8, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21110

Model for estimating power shortage in electric power systems with quadratic losses of power in transmission lines

A model for estimating power shortage in electric power systems with quadratic losses of power in transmission lines is studied. This model is designed to analyze problems of reliability of electric power systems. A method of presentation of this model in the form of a convex programming problem is given. An interior point algorithm is proposed for model implementation. This algorithm takes into account quadratic approximations of constraints functions. Results of the experimental study of the algorithm are presented.

Reliability of electric power systems: challenges in the deregulated environment — a research perspective

Electric power industry deregulation has brought about the unbundling of generation, transmission and distribution services and as such, new techniques for reliability assessment are being developed to account for the consequent structural changes in the restructured environment. The transition towards deregulation imposes several unique challenges for establishing reliability modeling paradigms. Addressing these concerns requires a comprehensive knowledge of the technical and economic issues involved and the identification of relevant research gaps. This paper presents a broader framework for the research perspectives to holistically address the significant issues that can profoundly impact the reliability studies in the liberalized environment. Starting from the improvisations in the reliability network equivalent techniques in vogue, this paper advocates the use of power flow tracing as a potential tool for reliability and well-being studies of power systems, and expands upon their practical implications.

Insulator condition analysis for overhead distribution lines using combined wavelet support vector machine (SVM)

Condition analysis of overhead power distribution system insulators using combined support vector machine (SVM) and wavelet multi-resolution analysis (MRA) seems to be promising for distribution system monitoring (DSM) automation to cope with the increasing system complexity. Though system well-being analysis for engineering applications has been used mostly for electric power system reliability studies, the same principle has been extended for assessing the condition of insulators in a distribution system based on the extent of their damage. Video surveillance with fixed cameras provide the required images of power lines along with insulators at regular intervals and same is sent to a control room using remote terminal units (RTUs) for analysis. Not only the health of the insulators, but also the sagging of the lines, breakage of both insulators and lines can be captured with such cameras. This paper mainly focuses on application of wavelet-transform based feature extraction for digital image processing and SVM for subsequent condition analysis of insulators. The most significant contribution of the paper is to compute the condition indices for overhead power distribution line insulators to overcome difficulties related to vehicular applications in video surveillance. The results contained in this paper validate the efficacy of the proposed methodology for wide-scale applications in overhead power distribution system monitoring (DSM) automation.

Study on Measure to the Reduction of the Surge Voltage on Low Voltage Circuit in Substation

In order to improve the reliability of electric power systems, it is important to reduce the malfunction of relay or the fault of low voltage control circuits in substation by switching and lightning surge. However, it is not enough that the study of intrusion of surge into the low voltage control circuits. We studied the terminal voltage of the control panel and analyzed the intrusion route of surge in substation.

PSCAD/EMTDC를 이용한 철도 고압 배전계통의 과도특성 해석 및 1선 지락사고에 대한 보호방안

철도에서의 고압배전선로는 역사조명 및 동력설비, 그리고 열차의 안전운행을 위한 신호설비의 전력을 공급해 주는 설비로 열차의 안전운행 및 철도 이용자의 서비스 향상을 위한 중요한 역할을 담당하고 있다. 또한 각종 전력기기의 전자화, 자동화로 인해 양질의 전력공급이 요구되며, 철도 이용자에 대한 보다 향상된 서비스를 제공과 역사내 전기에너지 사용의 급증으로 인한 전력공급의 신뢰성 확보가 요구된다.BR 본 논문에서는 철도고압배전계동의 고장현상을 분석하기 위하여 철도고압배전 설비중 접지계통과 비접지계통에 대해서 사고시 전압강하가 발생 여부와 사고를 제거하기 위해 차단기를 동작시켰을 때의 서지전압에 의한 과도특성을 PSCAD/EMTDC를 이용하여 모의하였으며, 이 사고모의 결과를 토대로 비접지 고압배전계동의 보호방법에 대한 대안을 제시하였다.

A Flexible Count Data Regression Model for Risk Analysis

In many cases, risk and reliability analyses involve estimating the probabilities of discrete events such as hardware failures and occurrences of disease or death. There is often additional information in the form of explanatory variables that can be used to help estimate the likelihood of different numbers of events in the future through the use of an appropriate regression model, such as a generalized linear model. However, existing generalized linear models (GLM) are limited in their ability to handle the types of variance structures often encountered in using count data in risk and reliability analysis. In particular, standard models cannot handle both underdispersed data (variance less than the mean) and overdispersed data (variance greater than the mean) in a single coherent modeling framework. This article presents a new GLM based on a reformulation of the Conway-Maxwell Poisson (COM) distribution that is useful for both underdispersed and overdispersed count data and demonstrates this model by applying it to the assessment of electric power system reliability. The results show that the proposed COM GLM can provide as good of fits to data as the commonly used existing models for overdispered data sets while outperforming these commonly used models for underdispersed data sets.

Enhancing reliability of electric power systems using superconductor devices

The possibility to improve the operation regime and the reliability of electric power systems using superconductor devices is considered.