Power System Reliability

The problem of defining and classifying power system stability has been addressed by several previous CIGRE and IEEE Task Force reports. These earlier efforts, however, do not completely reflect current industry needs, experiences and understanding. In particular, the definitions are not precise and the classifications do not encompass all practical instability scenarios. This report developed by a Task Force, set up jointly by the CIGRE Study Committee 38 and the IEEE Power System Dynamic Performance Committee, addresses the issue of stability definition and classification in power systems from a fundamental viewpoint and closely examines the practical ramifications. The report aims to define power system stability more precisely, provide a systematic basis for its classification, and discuss linkages to related issues such as power system reliability and security.

The problem of defining and classifying power system stability has been addressed by several previous CIGRE and IEEE Task Force reports. These earlier efforts, however, do not completely reflect current industry needs, experiences and understanding. In particular, the definitions are not precise and the classifications do not encompass all practical instability scenarios. This report developed by a Task Force, set up jointly by the CIGRE Study Committee 38 and the IEEE Power System Dynamic Performance Committee, addresses the issue of stability definition and classification in power systems from a fundamental viewpoint and closely examines the practical ramifications. The report aims to define power system stability more precisely, provide a systematic basis for its classification, and discuss linkages to related issues such as power system reliability and security.

District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand-outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations.

Much of the research has been focused on developing the optimization techniques, varying from classical to nontraditional soft computing techniques, to solve the distribution system planning problem. Most of the methods preserve the distinctions and niceties, but dependent on complex search algorithm with a lot of convergence related issues that require more time to reach a firm conclusion at planning stage. This paper proposes a simple direct solution that significantly reduces the inherent difficulties of finding the solution and ensures optimum solution at the same time. Moreover, the concept of principle of optimality is effectively used to make the proposed technique more computationally efficient and useful. The effectiveness of the developed planning technique has been verified with different test cases.

An electric utility-s main concern is to plan, design, operate and maintain its power supply to provide an acceptable level of reliability to its users. This clearly requires that standards of reliability be specified and used in all three sectors of the power system, i.e., generation, transmission and distribution. That is why reliability of a power system is always a major concern to power system planners. This paper presents the reliability analysis of Bangladesh Power System (BPS). Reliability index, loss of load probability (LOLP) of BPS is evaluated using recursive algorithm and considering no de-rated states of generators. BPS has sixty one generators and a total installed capacity of 5275 MW. The maximum demand of BPS is about 5000 MW. The relevant data of the generators and hourly load profiles are collected from the National Load Dispatch Center (NLDC) of Bangladesh and reliability index 'LOLP' is assessed for the period of last ten years.

Задача доказової стійкості схеми Фейстеля до диференціального аналізу була поставлена та розв’язана Ніберг та Кнудсеном; ними була виведена теоретична верхня межа імовірності існування диференціалів шифру, виражена через відповідні імовірності раундових функцій. Цей параметр дозволяє оцінити знизу складність проведення диференціальної атаки на довільний шифр, побудований на основі схеми Фейстеля. В немарковських схем. В даній роботі пропонується загальна методика побудови аналітичної оцінки верхньої межі імовірності існування диференціалів через параметри раундових функцій. Ця методика базується на принципах, які використовувались при доведенні результатів попередніх дослідників, однак вона дозволяє оцінювати немарковські шифри та будувати аналітичні оцінки автоматично, що виявляється корисним для оцінки стійкості складних схем шифрування, для яких традиційний математичний підхід вимагав би дослідження великої кількості різних випадків. Суть методики полягає у розгляданні можливих ш...

The legacy power grid has faced many challenges such as growing demand, which have negatively impacted the distribution system’s reliability. The huge socioeconomic costs attached to power interruptions have led to drastic changes within the grid to improve reliability. Efforts have been made to implement a Smart Grid (SG) with better monitoring and control of the grid to improve reliability, but additional studies have foreseen reliability enhancement with integration of Distributed Energy Resources (DERs). Traditional reliability assessment techniques have challenges of being complex and time consuming. There is therefore need to explore new modern techniques such as Machine Learning (ML) to overcome these challenges. This study evaluates reliability improvement upon integration of a solar photovoltaic (PV) array into the IEEE-34 node test feeder in ETAP software. On calculation of reliability indices, comparison is made between the system with a DER and the original one. The simulation results register substantial improvement in all reliability indices upon DER introduction. A load flow analysis is undertaken to comprehend dynamics responsible for the reliability gains. Reliability is found to improve the closer the DER is placed to the loads. An Artificial Neural Network (ANN) is implemented in MATLAB to predict reliability indices depending on the DER location and high accuracy is attained. The developed model is then validated for practical application, and accuracy still found high.

The composite power system reliability analysis is generally based on minimal path or cut enumeration, tracing of power flow paths from which the related reliability indices are calculated. The minimal cut set is a popular method in the reliability analysis for simple and complex configurations. Average availability of power supply at the consumer end is one of the reliability assessment parameter. This paper is concerned about the evaluation of this reliability index. A step by step procedure for a modified minimal cut set method is explained in this paper using IEEE 6 bus, 14 bus and Single area IEEE RTS 96 system. The proposed algorithm is easy to program and can be applicable to any system. The proposed algorithm is validated with the Classical Node Elimination method, Step by Step algorithm using Conditional Probability and Monte Carlo Simulation method. The proposed technique is tested with a practical example taken from Roy Billinton paper (Reliability evaluation in distribution and transmission systems).

In power system reliability evaluation, alternating renewal process is generally used to model the failure and repair cycle of a component. This means that after repair, the component is assumed to be restored to as good as new condition from the reliability perspective. However, in practice, there may exist an aging trend in some components as they grow old. This paper describes how aging characteristics of components may impact the calculation of commonly used reliability indices such as loss of load expectation (LOLE). In order to construct the system failure and repair history of components, sequential Monte Carlo simulation method using stochastic point process modeling is introduced. Three methods are described for this purpose and this methodology is applied to the Single Area IEEE Reliability Test System. The results are analyzed and compared.

As the components grow older, most power systems may enter a wear out stage indicating an aging trend. This paper is focused on aging effects in composite power system reliability evaluation. Quantitative reliability indices such as Loss of Load Expectation (LOLE) are calculated. The IEEE Reliability Test Systems is used to illustrate this technique.

As the components grow older, most power systems may enter a wear out stage indicating an aging trend. This paper is focused on aging effects in composite power system reliability evaluation. Quantitative reliability indices such as Loss of Load Expectation (LOLE) are calculated. The IEEE Reliability Test Systems is used to illustrate this technique.

In power system reliability evaluation, alternating renewal process is generally used to model the failure and repair cycle of a component. This means that after repair, the component is assumed to be restored to as good as new condition from the reliability perspective. However, in practice, there may exist an aging trend in some components as they grow old. This paper describes how aging characteristics of components may impact the calculation of commonly used reliability indices such as loss of load expectation (LOLE). In order to construct the system failure and repair history of components, sequential Monte Carlo simulation method using stochastic point process modeling is introduced. Three methods are described for this purpose and this methodology is applied to the Single Area IEEE Reliability Test System. The results are analyzed and compared.

A AS THE ELECTRICAL UTILITY INDUSTRY ADDRESSES ENERGY AND environmental needs through greater use of renewable energy, storage, and other technologies, power systems are becoming more complex and stressed. Increased dynamic changes that require improvements in real-time monitoring, protection, and control increase the complexity of managing modern grids. In an effort to ensure the secure operation of power systems, more attention is being given to voltage management. Voltage management includes addressing voltage stability and fault-induced delayed voltage recovery (FIDVR) phenomena. Deployment of phasor measurement unit (PMU) technology, in combination with recently developed methodologies for tracking voltage behavior, has resulted in improved real-time voltage monitoring, protection, and control. This article describes simple and accurate methodologies based on real-time measurement-and independent of the system model-designed for tracking both slowdeveloping and transient voltage stability conditions under various and changing system confi gurations. Tests with real-time supervisory control and data acquisition (SCADA) and PMU data, as well as data from comprehensive simulation studies, from the Bonneville Power Administration (BPA) and Southern California Edison (SCE) systems show very accurate detection as the system is approaching voltage instability. The calculated reactive power margin and other indices are easily visualized for operator awareness. For quickly developing disturbances, they allow the initiation of fast control and protection actions. This methodology also discriminates well between FIDVR and short-term

Electrical power disruptions have been a major limitation in our society Nigeria, as it has impact in our social-economical activities. This paper will critically examine the problems and costs related to the effect of power failures on commercial customers in Garden City Central Area of Port Harcourt, Rivers State. This work examine problems of electrical power transmission and distribution that influences power failures to commercial consumers with specific interest on mobile telecommunication firms within Garden City Central Area of Port Harcourt, Rivers State. Bearing in mind the model employed in analysis of power failures within Garden City Central Area, of Port Harcourt, Rivers State. It has been discovered that the power failure within the case study area is evenly distributed, thereby reducing cost on the commercial customers. Pearson"s correlation coefficients will be used in the cost analysis of comparing power from individual generating set and power from national grid. This work examines commercial power consumption connected to National electricity network (PHEDC) in Garden City Central Area of Port Harcourt, Rivers State. It analyses the cost implication of power supply outages for mobile telecommunication firms using Pearson"s correlation factor and the frequency distribution of the outage by a statistical model and recommendations are made.

Natural disasters has been causing an increasing amount of economic losses in the past two decades. Natural disasters, such as hurricanes, winter storms, and wildfires, can cause severe damages to power systems, significantly impacting industrial, commercial, and residential activities, leading to not only economic losses but also inconveniences to people's day-today life. Improving the resilience of power systems can lead to a reduced number of power outages during extreme events and is a critical goal in today's power system operations. This paper presents a model for decentralized decision-making in power systems based on distributed optimization and implemented it on a modified RTS-96 test system, discusses the convergence of the problem, and compares the impact of decision-making mechanisms on power system resilience. Results show that a decentralized decision-making algorithm can significantly reduce power outages when part of the system is islanded during severe transmission contingencies.

Older solid dielectric cables are now approaching the end of their life and failing. Consequently there has been a sustained effort for the development of techniques to assess the remaining life of in-service cables for the purpose of establishing replacement criteria. Because of the generally accepted belief that the failure mode is due to the aging of the insulation, these techniques have mainly focused on measuring changes in the electrical properties of the insulation. It has been determined that there are other failure modes associated with loss of the protective function of the jacketing material leading to corrosion and breaks in the metallic shields and poor contact between semicon and metallic shield, however, causing arcing damage and eventual failure of the cable. This failure mode is more prevalent in cables operated in a harsh chemical environment. This paper presents the results of a research program aimed at developing a test protocol that is based on evaluating the condition of all the cable components, and not just the insulation. The tests were designed to evaluate the condition ofjacket, extent of corrosion of the metallic shield, and degree of degradation of the cable insulation. The results are discussed in terms of correlations between the field measurement parameters and the condition of the cable, and prioritization criteria for cable replacement.

Transmission lines are among the most important power grid equipment in which their removal can lead to subsequent outages. One of the situations which lead to blackouts is multiple line outages. Therefore, multiple line outage detections (MLOD) are a necessity in the power system for protection actions. This paper proposes a fuzzy inference system (FIS) to identify multiple line outages. The proposed FIS can determine multiple line outage conditions by continuously monitoring the lines circuit breakers (CBs) status. For this purpose, by introducing the line CBs status as inputs, the status of the predefined line outage scenario is determined as the output of the proposed FIS. This study is helpful for the power system researchers to make decisions about power system protection. The proposed fuzzy MLOD system has the advantage of high precision in applying the fuzzy system as an artificial intelligence tool. For the reason of problem dimensions limitations, in this paper, just single and multiline outage contingencies are considered for the MLOD problem although the proposed method can be extended to detect triple and more line outage contingencies by definition the additional fuzzy rules. The proposed fuzzy MLOD system is tested on IEEE 5-bus system and the results are presented.

The transformer operates under different voltage levels, requiring much better safety. Several
faults can occur, such as over-current due to overloads and incipient faults, winding faults,
external short circuits, and terminal (internal) faults. There is a need for careful attention to any
transformer fault, as some can cause hazardous situations. A transformer protection device offers
creative protection, control, and monitoring solutions.
Instrument transformers scale high current or voltage values into small, uniform values that are
simple to manage for protective relays and measuring instruments. The instrument transformers
usually remain in operation for several years and are replaced only when a mechanical failure
occurs or physical life has expired. However, substation protection and control systems have
recently changed more frequently, predominantly electronic and computer-based systems.
However, incorporating new technologies can introduce challenges, especially when certain IED
vendors encounter compatibility issues in their communication capabilities.
There is only one way to solve this issue on the distribution and transmission network systems to
deploy new technology, such as one standard that will be able to interface different vendors
together, the bay process bus, and Standard Protocol IEC 61850. The standard of the IEC 61850
defined the communication networks in substations that will bring interoperable systems and
flexible architectures to the substation automation domain. This research focuses on the
transformer's current differential protection scheme and investigates the IEC61850 standardbased communication interoperability between two different IED vendors for transformer
protection. It also focuses on improving the transformer's operation speed and increasing the
operational flexibility, reliability, and stability of a protection scheme for internal and external faults.
The research will use the modified IEEE Nine-Bus system to develop and implement a method of
testing the multi-vendor IED based on Hardware-In-Loop (HIL) configuration with the RTDS.
Different software environments were used for developing and implementing a current differential
protection scheme, and the performance of various types of faults was analysed. The utilization
of the IEC 61850 standard based on the current differential protection scheme is developed to
achieve interoperability GOOSE between the IEDs. Speed and reliability can be enhanced by
using the standard GOOSE message applications for the Transformer Protection Relay System
using the IEC61850 standard.
Keywords: Transformer protection, IEC 61850 standard, Current differential protection scheme,
Interoperability, Hardware-In-Loop, GOOSE message, RTDS, IED, and RSCAD.

The performance evaluation of a power system can be carried out through deterministic and probabilistic approaches. Deterministic methods presents the basic limitation of not considering the essentially stochastic nature of power systems behavior mainly due to random equipment outages and load. Therefore, the adequacy analysis of a power system should be performed by using stochastic methods such as probabilistic power flow and composite generation/transmission reliability. The performance indicators are based on the analysis of several possible system operating states, including combination of generator, transformer and line outages, load fluctuations, etc. To achieve a reasonable accuracy in estimating the probabilistic indices we may have to perform a great number of system contingencies. Therefore, in the contingency analysis process, specially in dealing with heavily stressed systems, there may be situations where the Newton-Raphson algorithm does not converge to a solution. These system solvability problems may be alleviated by calculating the minimum load shedding in order to bring solvability to an otherwise unsolvable power flow. In the considered approach, the process of computing the minimum load shedding is carried out by an OPF solved by a direct interior point (IP) method based on the primal-dual logarithm barrier algorithm. This paper describes the adopted approach to calculate probabilistic indicators of power system performance by combining the nonlinear OPF solved by the IP algorithm and the Monte Carlo simulation method. Applications to a 1600-bus network derived from the Brazilian South/Southeast/Central West system are presented and discussed.

Restructuring of the power industry worldwide has brought the issue of market competitiveness to the forefront. While "vertical" market power has been limited by disaggregating generation and transmission, nondiscriminatory access to the transmission system by power suppliers, and the creation of the independent system operator (ISO), "horizontal" and localized market power still survives. In the last few years, the issue of a small number of generators exercising market power has received a great deal of attention, and much has been published on how to identify and mitigate such abuse by market management measures. This paper focuses on the analysis and mitigation of market power in electricity supply.

Th& paper presents an integrated approach to power system reliability assessment. It gives an updated view of the subject and aims to unify, classify and extend some fundamental ideas and controversial issues which provide theoretical and practical support to these studies. The resulting conceptual framework lays the basis for a useful taxonomy which may be recalled for development or comparison of dissimilar techniques and computational programs which are frequently used in this fieM of engineering.

As the US power systems continue to increase in size and complexity, including the growth of smart grids, larger blackouts due to cascading outages become more likely. Grid congestion is often associated with a cascading collapse leading to a major blackout. Such a collapse is characterized by a self-sustaining sequence of line outages followed by a topology breakup of the

One of the key parts of overhead transmission lines that support and insulate the power transmission line is the string insulator discs. This need involves a meticulous design of string insulators for achieving high string efficiency, this is necessary for efficient power transmission. This paper has two aims, first improving and developing the efficiency of string insulators of overhead transmission lines 33kV and 132kV to be efficient, properly insulated and safe. Based on an optimum value of the capacitance (self-capacitance) which can be achieved via the proposed algorithm named Modified Particle Swarm Optimization (MPSO) technique which is the second aim of this paper. The MPSO algorithm tuned the self-capacitance (Cnew) as well as operating the model at the high efficiency of the string insulators with respect to its mechanical effectiveness. Moreover, analysis and evaluations of the systems (33kV and 132kV) as a classic model, proposed model and the MPSO have been carried out by MATLAB/Simulink R2022b environment. On the basis of the simulation findings, this paper produced a specific theoretical design for two transmission line systems 33kV and 132kV; where remarkable that the string efficiencies of 33kV and 132kV systems increased by 14.24% and 64.54% respectively. Also, compared the results between the proposed MPSO and conventional PSO.

A power distribution system reconfiguration methodology considering the reliability and the power loss is developed in this paper. Probabilistic reliability models are used in order to evaluate the reliability at the load points. An algorithm for finding the minimal cut sets is utilized to find the minimal set of components appearing between the feeder and any particular load point. The optimal status of the switches in order to maximize the reliability and minimize the real power loss is found by a binary particle swarm optimization-based search algorithm. The effectiveness of the proposed methodology is demonstrated on a 33-bus and a 123-bus radial distribution system.

Fault at transmission line system may lead to major impacts such as power quality problems and cascading failure in the grid system. Thus, it is very important to locate it fast so that suitable solution can be taken to ensure power system stability can be retained. The complexity of the transmission line however makes the fault point identification a challenging task. This paper proposes an enhanced fault detection and location method using positive and negative-sequence values of current and voltage, taken at both local and remote terminals. The fault detection is based on comparison between the total fault current with currents combination during the pre-fault time. While the fault location algorithm was developed using an impedance-based method and the estimated fault location was taken at two cycles after fault detection. Various fault types, fault resistances and fault locations have been tested in order to verify the performance of the proposed method. The developed algorithm...

In the coming years, ICTs aim to converge with energy systems to make them smarter, more efficient, and more reliable. With the advent of embedded submetering, the energy information available will become more granular and more easily attributable to specific appliances or systems. The proliferation of thousands of IoT sensors throughout the power grid will create volumes of information about usage patterns, failures or the state of assets hitherto inconceivable. Rapid advances in machine learning and big data analytics are enabling the emergence of a wide range of disruptive energy products and personalized services that will benefit and empower digital citizens. This whole transition from the smart grid toward the digital energy platform is also posing new challenges to security and privacy. Definitively, this will change markets, business, and employment.

This paper presents a methodology in order to evaluate the security of electrical industrial systems considering security, quality, reliability and availability factors and the system response to sudden disturbances such as short circuit and harmonics. The models proposed using the probabilistic networks theory: Bayesian Networks and Generalized Stochastic Petri Nets. The obtained results allow the identification of hidden failures and erroneus coordination of protection. The models are tested on the IEEE 493 system proposed by the IEEE Gold Book.

This paper presents the improvement of the protectionof Power Distribution Networks (PDNs)when power transformers and electric motors are protected only with Fault Current Limiting Devices (FCLDs). In assessing the state of the PDNs from normal topost-fault conditions, objective comparisons are made between two types of results taking into account whenthere is not presence of FCLDs andwhen FCLDsare used as protection systemduring abnormal conditions. The approach to this study isperformed using Matlab/Simulink and it was concluded that the FCLDsperfectly enhance the protection of expensive equipment in the PDN.

This paper investigates the comparative effects of static series synchronous compensator (SSSC) and static synchronous compensator (STATCOM) on Nigeria's 48-bus, 330 kV transmission system. The SSSC is connected in series with a transmission line, while the STATCOM is shunt-connected for reactive compensation. The study aims to determine which of the two FACTS devices provides greater improvement to the voltage profile of Nigeria's 48-bus, 330 kV transmission system. The network was modeled using the power system analytical tool (PSAT) and analyzed using MATLAB. Simulation results demonstrate significant improvement across all 48 buses when both SSSC and STATCOM devices are integrated into the network. Specifically, the placement of STATCOM led to a 1.5% increase in voltage profile at the highest bus (Bus 18), from 314.8 kV to 319.5 kV. Conversely, SSSC resulted in a 3.3% increase in bus voltage profile compared to the base case, and a 1.8% increase compared to STATCOM, with Bus 18 reaching 325.3 kV. These findings suggest that for voltage profile improvement in power network design, SSSC FACTS should be prioritized over the shunt counterpart due to its greater impact.

Дніпровський національний університет імені Олеся Гончара Проектування архітектури системи є одним з найважливіших етапів створення проекту. Під час проектування системи приймаються відповідні проектні рішення, які впливають на поведінку системи та її складність. Основною метою при виборі програмної архітектури є боротьба з потенційною складністю, яка властива сучасним програмним системам,

The battery energy storage systems (BESSs) have been increasingly installed in the power system, especially with the growing penetration rate of the renewable energy sources. However, it is difficult for BESSs to be profitable due to high capital costs. In order to boost the economic value of BESSs, this paper proposes a hierarchical energy management system (HiEMS) to aggregate multiple BESSs, and to achieve multi-market business operations. The proposed HiEMS optimizes the multi-market bids considering a realistic BESS performance model, and coordinates the BESSs and manages their state of charge (SOC) values, according to their price penalties based on dynamically generated annualized cost. By taking part in the energy market and regulation market at the same time, the cost-performance index (CPI) of the BESS aggregation is greatly improved. The impact of photovoltaic generation (PV) on system performance and CPI is also studied.

This paper proposes a new methodology to evaluate system generating capacity reliability indices considering time-dependent power sources and loads. Based on sequential Monte Carlo simulation (MCS) and the cross-entropy (CE) method, the basic idea is to find an optimal distortion for the equipment transition rates using the CE concepts. A chronological simulation is then carried out using these newly found optimal reference parameters. This process suitably modifies the chronological evolution of the system in order to improve its statistical efficiency and convergence properties. As a result, the computational efforts of the sequential simulation can be greatly reduced while retaining many of its main advantages. Comparisons with the chronological, pseudo-chronological, and quasi-sequential MCS are carried out using the IEEE-RTS-96 (Reliability Test System) and modifications of this system that include renewable sources.

The paper considers a model approach to solving the problem of diagnostics and control of dynamic objects based on the application of integral equations. The growing complexity of energy facilities, taking into account their dynamic properties, increasing requirements for accuracy and objectivity of decisions lead to the need to develop new effective algorithms for mathematical software for diagnostic information processing systems to meet these requirements and automate the process of controlling power plants. Currently, the direction based on the restoration of the model (operator) for diagnostic purposes is being developed in technical diagnostics. It is generally assumed that faults change only the parameters of the model of objects of control, which are evaluated by diagnostic methods of parametric identification, but there may be cases when you need to take into account changes in the structure of the object. Real objects, as a rule, have both nonlinear and dynamic properties....

The performance evaluation of a power system can be carried out through deterministic and probabilistic approaches. Deterministic methods presents the basic limitation of not considering the essentially stochastic nature of power systems behavior mainly due to random equipment outages and load. Therefore, the adequacy analysis of a power system should be performed by using stochastic methods such as probabilistic power flow and composite generation/transmission reliability. The performance indicators are based on the analysis of several possible system operating states, including combination of generator, transformer and line outages, load fluctuations, etc. To achieve a reasonable accuracy in estimating the probabilistic indices we may have to perform a great number of system contingencies. Therefore, in the contingency analysis process, specially in dealing with heavily stressed systems, there may be situations where the Newton-Raphson algorithm does not converge to a solution. These system solvability problems may be alleviated by calculating the minimum load shedding in order to bring solvability to an otherwise unsolvable power flow. In the considered approach, the process of computing the minimum load shedding is carried out by an OPF solved by a direct interior point (IP) method based on the primal-dual logarithm barrier algorithm. This paper describes the adopted approach to calculate probabilistic indicators of power system performance by combining the nonlinear OPF solved by the IP algorithm and the Monte Carlo simulation method. Applications to a 1600-bus network derived from the Brazilian South/Southeast/Central West system are presented and discussed.

Today's electricity paradigm requires that the notion of active distribution systems be introduced at both undergraduate and graduate curricula. This involves not only the customary theoretical foundations but also a suitable power engineering lab where flexible enough and affordable resources allow students and researchers to carry out hands-on experiments reinforcing the concepts explained in the classroom. This paper describes the smart grid lab of the Power Engineering Group at the University of Seville, composed of a scaled-down distribution system, along with the required control and monitoring equipment, designed to help its users easily grasp the major influence that distributed generation and storage devices exert in the operation of MV distribution systems.

A Markov model describes a randomly varying system that satisfies the Markov property. This means that future and past states at any time are independent of the current state. The most commonly used Markov models are Markov chains and higher-order Markov chains. Therefore, three types of Markov models are proposed in this chapter of the book: (i) Supply chain management, (ii) Markov queue waiting time monitoring, and (iii) Markov fuzzy time series forecasting. The introduction introduces the Markov chain (MC) and summarizes the most important aspects of Markov chain analysis. Using the classical (0, Q) policy, the first model explores a Markov queue coupled to a storage system. The second model focuses on the M/M/1/N service mode and develops a control chart for an Ms/Ms/1/N type simulated queue to monitor customer waiting times. The third is a higher-order Markov model (HOMM), which uses fuzzy sets to predict future states based on given hypothetical time series data. Numerical cal...

Reliability is one of the main objectives that should be considered in Transmission Expansion Planning. However, the high computational demands of traditional approaches mean that they may be unmanageable in real case studies. We propose a simple reliability measure that can be easily calculated based on topology and basic power system information. The measure is easily calculated and has no need for power flow calculations. The use of this measure has been demonstrated in a case study using data from the Spanish power grid.

Power systems consist of generation, transmission, and distribution of power to customers. To meet the ever increasing population demand, the power industry has also grown by increasing the number of devices and incorporating highly complex as well as expensive components into the power system. increasing size of the power system transmission networks has made the system to be prone to various disturbances which could result to system instability. Main factor causing voltage instability is the inability of the power system to maintain a proper balance of reactive power and voltage control. The driving force for the voltage instability is the load. Using the shunt compensating devices, the reactive power balance of the power system can be maintained. This paper proposes a control model based on PI control, which can self-adjust the control gains during a disturbance such that the performance always matches a desired response, regardless of the change of operating condition. A Single ...

The problem of defining and classifying power system stability has been addressed by several previous CIGRE and IEEE Task Force reports. These earlier efforts, however, do not completely reflect current industry needs, experiences and understanding. In particular, the definitions are not precise and the classifications do not encompass all practical instability scenarios. This report developed by a Task Force, set up jointly by the CIGRE Study Committee 38 and the IEEE Power System Dynamic Performance Committee, addresses the issue of stability definition and classification in power systems from a fundamental viewpoint and closely examines the practical ramifications. The report aims to define power system stability more precisely, provide a systematic basis for its classification, and discuss linkages to related issues such as power system reliability and security.

Older solid dielectric cables are now approaching the end of their life and failing. Consequently there has been a sustained effort for the development of techniques to assess the remaining life of in-service cables for the purpose of establishing replacement criteria. Because of the generally accepted belief that the failure mode is due to the aging of the insulation, these techniques have mainly focused on measuring changes in the electrical properties of the insulation. It has been determined that there are other failure modes associated with loss of the protective function of the jacketing material leading to corrosion and breaks in the metallic shields and poor contact between semicon and metallic shield, however, causing arcing damage and eventual failure of the cable. This failure mode is more prevalent in cables operated in a harsh chemical environment. This paper presents the results of a research program aimed at developing a test protocol that is based on evaluating the condition of all the cable components, and not just the insulation. The tests were designed to evaluate the condition ofjacket, extent of corrosion of the metallic shield, and degree of degradation of the cable insulation. The results are discussed in terms of correlations between the field measurement parameters and the condition of the cable, and prioritization criteria for cable replacement.