Search

A substantial quantity of testing has been performed on the degradation of paper insulation over the decades. The aim being to better educate the electrical industry on how to best operate expensive assets, such as transformers. The longevity of paper insulation is frequently tested using accelerated ageing experiments, where the effects of temperature and the chemical environment on paper lifespan can be studied. Such research has resulted in paper life expectancy curves being published by the IEEE and the IEC. The investigations tend to use sealed vessels. However, the disadvantage of using this method is that the water content of the paper changes during the ageing process which then changes the ageing rate. In these ageing experiments the water and oxygen content was controlled using a special test rig to compare the ageing rate to previous work and to determine the ageing effect of paper by combining temperature, water content of paper and oxygen content of the oil. We found that the rate of paper ageing can be more accurately determined by controlling the water and oxygen during the experiment which then produced noticeable changes in predicting life expectancy. [ABSTRACT FROM PUBLISHER]

Provides instructions and guidelines to prospective authors who wish to submit manuscripts. [ABSTRACT FROM AUTHOR]

The article relates the editor's view regarding his partnership with SPi Publishing Services. They are aiming to offer pre-submission professional editing services at full cost to the authors. In this context, the editor mentioned the new categories of papers and their corresponding terms by various electrical societies and organizations.

This paper analyzes numerically the approach reported in the companion paper for identifying generation investment equilibria in an electricity market where the producers behave strategically. To this end, a two-node illustrative example and a large-scale case study based on the IEEE reliability test system (RTS) are examined and the results obtained are reported and discussed. [ABSTRACT FROM PUBLISHER]

This paper proposes a comprehensive framework to detect non-technical losses (NTLs) and recover electrical energy (lost by abnormalities or fraud) by means of a data mining analysis, in the Spanish Power Electric Industry. It is divided into four section: data selection, data preprocessing, descriptive, and predictive data mining. The authors insist on the importance of the knowledge of the particular characteristics of the Power Company customer: the main features available in databases are described. The paper presents two innovative statistical estimators to attach importance to variability and trend analysis of electric consumption and offers a predictive model, based on the Generalized Rule Induction (GRI) model. This predictive analysis discovers association rules in the data and it is supplemented by a binary Quest tree classification method. The quality of this framework is illustrated by a case study considering a real database, supplied by Endesa Company. [ABSTRACT FROM PUBLISHER]

Optimal deployment, with respect to locations, capacity sizes, and types of distributed energy resources (DERs), which are the main components in a microgrid system, are chosen for study in this paper. For the selection of optimal locations of DERs, the loss sensitivity index of each bus is taken into account. Whereas optimal size and its separation among microturbines, diesel generators and combustion turbines at each bus location are performed on the basis of the maximum benefit-to-cost ratio of the microgrid owner, obtained by using the particle swarm optimization technique and with respect to their reliable catering and quality of power as well as heat (i.e., combined-heat-and-power (CHP) operation) for customers. This paper conducts four separate case studies--two on 6-bus systems (radial and meshed) and resting on 14-bus systems (the IEEE system and radial system)--to show how much these systems are economically feasible for investment planning when cost and CHP benefits of various types of DERs are taken into account. Load profiles, tariffs, as well as the constructional cost of the microgrid itself are addressed in the six-bus meshed network and its central DER location in a district-heating paradigm is also done separately. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of a multiyear security constrained hybrid generation-transmission expansion planning. It is assumed that the overall generation requirements of a network are known along the planning horizon, but their allocations are unknown. Moreover the fuel cost throughout the net- work is not uniform. By allocating the overall generation capacity among the grid nodes, and determining the new transmission element additions along the planning horizon, the overall cost of the system is minimized. The problem is formulated as a mixed integer nonlinear programming problem, which for a large-scale system is very difficult to solve. In this paper a new constructive heuristic approach is proposed, so that the problem can be readily solved. To assess the capabilities of the proposed approach, two networks are studied: the Garver test grid as a small grid and the Iranian power grid as a large-scale grid. [ABSTRACT FROM AUTHOR]

Resistance spot welding is used to join two or more metal objects, and the technique is widely used in, for example, the automotive and electrical industries. This paper introduces the use of the κ-nearest-neighbor (κnn) method to identify similar welding processes. The two main benefits achieved from knowing the most similar process are the following: 1) The time needed for the setup of a new process can be substantially reduced by restoring the process parameters leading to high-quality joints, and 2) the quality of new welding spots can be predicted and improved using the stored information of a similar process. In this paper, the basic κnn method was found to be inadequate, and an extension of the κnn method, which is called similarity measure, was developed. The similarity measure provides information of how similar the new process is by using the distance to the κnns. Based on the results, processes can be classified, and the similarity measure proved to be a valuable addition to the existing methodology. Furthermore, process information can provide a major benefit to welding industry. [ABSTRACT FROM AUTHOR]

The fine print note (FPN) No. 1 in 2005 National Electrical Code (NEC) Article 501.8 (B) [ANSI/NFPA 70, National Electrical Code, 2005 (NEC)] cautions users to "consider the temperature of internal and external surfaces that may be exposed to the flammable atmosphere" when putting a motor into service in a Class I, Division 2 environment. Thus, it is critical that manufacturers and users of industrial electric motors understand that internal peak temperatures exceed the external peak temperatures. This paper presents three common IEEE 1349 [IEEE 1349-2001, IEEE Guide for the Application of Electric Motors in Class I, Division 2 Hazardous (Classified) Locations] test methods used by manufacturers to determine these internal peak temperatures. Potential test method error and the test results from the three test methods are also presented. IEEE 1349 provides only guidance when performing these test methods so this paper intends to provide additional clarification. The test motors presented in this paper are low voltage, ac induction, severe-duty, energy-efficient, totally enclosed fan-cooled motors commonly used in the "Petrochemical Industry." [ABSTRACT FROM AUTHOR]

This paper addresses the self scheduling problem of a price-taker power producer. It focuses on risk modeling, emphasizing the tradeoff existing between maximum profit and minimum risk. The paper analyzes a self-scheduling model that considers simultaneously profit and risk. This model Is formulated as a mixed-Integer quadratic programming problem, which Is solved using commercially available software. Relevant results from a realistic case study are discussed. [ABSTRACT FROM AUTHOR]

In Part II of this paper, we present formulations for three two-settlement market models: Baseline cost-minimization (\textitStoch- \textitOpt); and two sequential market models in which an independent system operator (ISO) runs real-time (RT) balancing markets after making day-ahead (DA) generating unit commitment decisions based upon deterministic wind forecasts, while virtual bidders arbitrage the two markets ( ${{\textit{Seq}}}$ and ${{\textit{Seq}}}$- ${{SS}}$). The latter two models differ in terms of whether some slow-start generators can self-schedule in the DA market while anticipating probabilities of RT prices. Models in ${{\textit{Seq}}}$ and ${{\textit{Seq}}}$- ${{SS}}$ build on components of the two-settlement equilibrium model ( \textitStoch- ${{MP}}$) defined in Part I of this paper [J. Kazempour and B. F. Hobbs, “Value of flexible resources, virtual bidding, and self-scheduling in two-settlement electricity markets with wind generation - Part I: Principles and competitive model,” IEEE Trans. Power Syst., vol. 33, no. 1, pp. 749–759, Jan. 2018]. We then provide numerical results for all four models. A simple single-node case illustrates the economic impacts of flexibility, virtual bidding, and self-schedules, and is followed by a larger case study based on the 24-node IEEE reliability test system. Their results confirm that flexible resources, including fast-start generators and demand response, can reduce expected costs in a sequential two-settlement market. In addition, virtual bidders can also improve the functioning of sequential markets. In some circumstances, virtual bidders (together with self-scheduling by slow-start generators) enable deterministic ISO DA markets to obtain the least (expected) cost unit commitments. [ABSTRACT FROM AUTHOR]

This paper provides a discussion on the theory behind reducing the risk and severity of an arc flash incident. In particular, the variables associated with the calculations of energy from an arcing fault are presented in an effort to show the futility of present methods for determining incident energy levels in the electrical industry. A number of commonly ignored design concepts that significantly reduce the risk of electrical hazards will be discussed, two of which include: 1) system grounding; and 2) solid insulation. This paper will discuss risk and the management of risk as a means of reducing the probability of an incident. It will then show how risk reduction should be used in the design, construction, operation, and maintenance of electrical equipment as means for the safeguarding of employees in the workplace. [ABSTRACT FROM PUBLISHER]

For more than 50 years, research has shown that a correlation exists between the number of incidents, injuries, and fatalities. Investigation into electrical incidents indicates that there is more to understand about the causal effect of the number of incidents occurring. Many electrical incidents are caused by undesirable actions of people. These are called unsafe acts. Why do people perform unsafe acts? Lack of experience, knowledge, or skills often come into play. What people believe about safety is another important component. The intent of this paper is to explore these relationships and to focus on unsafe behaviors and beliefs about safety. By investigating and using the actions outlined in this paper, fewer incidents will occur resulting in a decrease in injuries and fatalities. [ABSTRACT FROM PUBLISHER]

The concept of adjustable combinatorial products within the scope of the day-ahead electricity market is introduced in this paper. These adjustable products comprise simple and linked profile block offers/bids, with a variable energy quantity profile during the block periods. In the proposed formulation, these blocks can be partially cleared, namely, the indivisibility of the classical profile blocks that are present in European markets is relaxed. This flexibility allows the elimination of paradoxically accepted and rejected blocks and, thus, the elimination of iterative heuristic procedures for their handling. Such modeling is not possible as a mixed-integer linear programming problem, due to the inherent indivisibility denoted by the use of binary variables. Additionally, advanced profile bids are formulated for demand entities, called “joint demand profile block bids” in this paper, which involve not only inter-temporal relations, but also spatial relations with each other. This two-dimensional relation between demand profile blocks is novel and is deemed feasible with the model presented here. These advanced profile orders are incorporated in a day-ahead market problem, formulating a mixed complementarity problem model, which is solved using commercial solvers. The model is validated using the IEEE RTS-96 system; nevertheless, its scalability to large real-world power systems is straightforward. [ABSTRACT FROM PUBLISHER]

This paper presents the study of the propagation of the effects of uncertainties in a typical measurement system for modern power networks. Nowadays there is a strong demand from the electricity industry of simple and ready-to-use solutions for calculating uncertainty in such “new” measurement systems. To this purpose a simplified approach is presented whose results are shown to be in good agreement with those provided by conventional but more complex methods. Two applications, rather simple but very common, are considered in this paper. In the first one, the measurement of a voltage phasor is considered and the measurement chain is made by an low power instrument transformer (LPIT) and a converter used for adapting the level of signals from the LPIT to the inputs of intelligent electronic device. The second application deals with the measurement of active power of a system made by a low power voltage transformer (LPVT), a low power current transformer and a powermeter. [ABSTRACT FROM AUTHOR]

If an extreme contingency strikes the Kinmen Island power system in Taiwan, it is very likely to cause blackouts. Although an underfrequency protection scheme has been applied, some drawbacks of the protection scheme hinder the Kinmen power system from avoiding blackouts. In the past decade, several blackouts have occurred in the Kinmen power system. To avoid further possible blackouts, a special protection system (SPS) is summoned. This paper describes the design guidelines and deployment procedures of an SPS for the Kinmen power system. The design depends on the Kinmen power system characteristics, and the deployment hinges upon the supervisory control and data acquisition system. Exquisite software was also developed to testify the Kinmen system SPS. Operational records have demonstrated that the proposed SPS can indeed prevent blackouts from occurring in the Kinmen power system. The design, implementation, and operation of the SPS dealt with in this paper might foster further deployments of other SPSs. [ABSTRACT FROM AUTHOR]

In Australia and many other countries, distribution network service providers (DNSPs) have an obligation to their customers to provide electrical power that is reliable and of high quality. Failure to do so may have significant implications ranging from financial penalties theoretically through to the loss of a license to distribute electricity. In order to ensure the reliability and quality of supply are met, DNSPs engage in monitoring and reporting practice. This paper provides an overview of a large long-running power-quality monitoring project that has involved most of Australia's DNSPs at one time or another. This paper describes the challenges associated with conducting the project as well as some of the important outcomes and lessons learned. A number of novel reporting techniques that have been developed as part of the monitoring project are also presented. A discussion about large-volume data management, and issues related to reporting requirements in future distribution networks is included. [ABSTRACT FROM PUBLISHER]

Converting wind energy into ammonia (WtA) has been recognized as a promising pathway to produce “green” ammonia compared with traditional coal-based technologies. As the key part of WtA, Power-to-Ammonia (PtA) has great potential to facilitate the usage of wind generation. This paper proposes a co-planning approach for regional wind resources-based ammonia industry and the electric network (EN). To this end, PtA is first modeled as a flexible power load of power systems with spatial and temporal constraints on hydrogen supply chains (HSC). Then a novel co-planning model of WtA and EN is established to optimize the WtA configuration and the EN expansion. An alternating direction method of multipliers (ADMM) based algorithm is introduced to effectively solve this model. Real data of Inner Mongolia Province in China is adopted to verify the effectiveness and significance of the proposed approach. It is shown that the siting and operation flexibility of PtA with HSC can reduce the expansion burden of EN. The co-planning of WtA and EN can significantly enhance wind power utilization and reduce total investment costs. Furthermore, feasibility analysis on WtA in comparison with coal-to-ammonia (CtA) and ultra-high voltage transmission (UHV) provides helpful guidelines for the realization of WtA. [ABSTRACT FROM AUTHOR]

The first of this two-paper series proposes a methodology to characterize generation investment equilibria in a pool-based network-constrained electricity market, where the producers behave strategically. To this end, the investment problem of each strategic producer is represented using a bilevel model, whose upper-level problem determines the optimal investment and the supply offering curves to maximize its profit, and whose several lower-level problems represent different market clearing scenarios. This model is transformed into a mathematical program with equilibrium constraint (MPEC) through replacing the lower-level problems by their optimality conditions. The joint consideration of all producer MPECs, one per producer, constitutes an equilibrium problem with equilibrium constraints (EPEC). To identify the solutions of this EPEC, each MPEC problem is replaced by its Karush-Kuhn-Tucker (KKT) conditions, which are in turn linearized. The resulting mixed-integer linear system of equalities and inequalities allows determining the EPEC equilibria through an auxiliary MILP problem. [ABSTRACT FROM PUBLISHER]

In centralized day-ahead electricity markets with marginal pricing, unit commitment costs and capacity constraints give rise to non-convexities which may result in losses to some of the participating generating units. Therefore, a recovery mechanism is required to compensate them. In this paper, we present and analyze several recovery mechanisms that result in recovery payments after the market is cleared. Each of these mechanisms results in a different type and/or amount of payments for each participating unit that exhibits losses. We also propose a methodology for evaluating the bidding strategy behavior of the participating units for each mechanism. This methodology is based on the execution of a numerical procedure aimed at finding joint optimal bidding strategies of the profit-maximizing units. In a companion follow-up paper (Part II), we apply this methodology to evaluate the performance and incentive compatibility of the suggested recovery mechanisms on a simplified test case model of the Greek electricity market. [ABSTRACT FROM PUBLISHER]

As the typical clean and renewable energy, wind energy has witnessed a continuous annual increase in the last few decades. Due to the random and intermittent characteristics, the wind producers in the electric market meet serious financial losses caused by the deviation between the actual power output and forecasting result. It is difficult to increase the accuracy of forecasting in a short time. How to improve the financial income has become a major task to wind producers and academia. Being the backbone network of the offshore wind farms (OWFs), voltage source converter-based multi-terminal HVdc system (VSC-MTdc) has been regarded as one of the effective solutions to transport wind power. In this paper, an optimal distribution method is proposed for VSC-MTdc system integrating OWFs to reduce the financial loss due to wind power output deviation. The proposed method could be divided into two optimizing functions. The first optimizing function of the proposed method is to analyze the onshore external system according to the historical system operation data and adjust the droop coefficient with the analytic hierarchy process. The second optimizing function of the proposed method is to do further adjusting with the regulating price. With the case study, the proposed optimal distribution method has proved that it can bring more benefit to wind producers. [ABSTRACT FROM AUTHOR]

This paper proposes a methodology for choosing the best transmission expansion plan considering various types of security (operating reliability) criteria. The proposed method minimizes the total cost that includes the investment cost of transmission as well as the operating cost and standby cost of generators. The purpose of the study is development of new methodology for solving transmission system expansion planning problem subject to (N - α) contingency criteria which are essentially extensions of the (N-1) contingency criterion. The transmission expansion problem uses an integer programming framework, and the optimal strategy is determined using a branch and bound method that utilizes a network flow approach and the maximum flow-minimum cut set theorem. The characteristics of the proposed method are illustrated by applying it to a five-bus system and a 21-bus system. The results of these case studies demonstrate that the proposed method provides a practical way to find an optimal plan for power system expansion planning. [ABSTRACT FROM AUTHOR]

The procedures of asset-management have been developed into a central element of network operation and planning in liberalised electric markets of power supply for the present. The method of asset management considers all relevant life cycle cost related to the network equipment and provides strategies for reinvestment, maintenance and fault elimination. However, the method requires practical information about the available failure statistic from distribution networks, as well as about the reliability evaluation of equipment installed in distribution network. For the quantitative evaluation we collect failure record data of distribution networks in the special failure statistic. Furthermore, this paper represents the first attempt at modeling the component reliability for representative electrical components due to electrical stress, mechanical stress, temperature and time, which takes general aging mechanisms of insulating materials into consideration. Thus the proposed models provide reliability estimates, e.g. failure probability and failure rate for distribution systems. These models can be not only parameterized with a great deal of statistical data but also determined by aging tests and breakdown tests being available for the probabilistic assessment. Our results imply that the assessment approach for component reliability will motivate a need for reasonable and accurate data at an early decision-making stage in future deregulation of electric power market. [ABSTRACT FROM AUTHOR]

This paper presents a multiperiod energy acquisition model for a distribution company (Disco) with distributed generation (DG) and interruptible load (IL) in a day-ahead electricity market. Assuming that cost information for individual generation companies (Gencos) and Discos is known, the Disco's energy acquisition strategy is modeled as a bilevel optimization problem with the upper subproblem representing individual Discos and the lower subproblem representing the independent system operator (ISO). The upper subproblem maximizes individual Discos' revenues. The lower subproblem simulates the ISO's market clearing problem that minimizes generation costs and compensation costs for interrupting load. The bilevel problem is solved by a nonlinear complementarity method. An 8-bus system is employed to illustrate the proposed model and algorithm. In particular, the roles of DGs and ILs to alleviate congestion are analyzed. [ABSTRACT FROM AUTHOR]

In this paper, a new system splitting scheme based on the unified stability control framework is proposed. Compared with the conventional system splitting scheme, the new method is much more effective under complicated oscillation scenarios. Under the unified stability control framework, different emergency control measures can be evaluated and compared with each other. The system splitting strategy will be applied to the system only when the analysis shows that the splitting is necessary or reasonable. Related algorithms are described in detail in this paper. The advantages and effectiveness of the new scheme can be justified through the testing cases. [ABSTRACT FROM AUTHOR]

This paper evaluates the usefulness of publicly available electricity market information in forecasting the hourly Ontario energy price (HOEP). In order to do so, relevant data from Ontario and its neighboring electricity markets, namely, New York, New England, and PJM electricity markets, are investigated, and a final set of explanatory variable candidates that are available before real-time are selected. Multivariate transfer function and dynamic regression models are employed to relate HOEP behavior to the selected explanatory variable candidates. Univariate ARIMA models are also developed for the HOEP. The HOEP models are developed on the basis of two forecasting horizons, i.e., 3 h and 24 h, and forecasting performance of the multivariate models is compared with that of the univariate models. The outcomes show that the market information publicly available before real-time can be used to improve HOEP forecast accuracy to some extent; however, unusually high or low prices remain unpredictable, and hence, the available data cannot lead to significantly more accurate forecasts. Nevertheless, the generated forecasts in this paper are significantly more accurate than currently available HOEP forecasts. To analyze the relatively low accuracy of the HOEP forecasts, comparisons are made with respect to ARIMA models developed for locational marginal prices (LMPs) of Ontario's three neighboring markets, and price volatility analyses are presented. [ABSTRACT FROM AUTHOR]

This paper presents a coevolutionary approach to analyzing supply function equilibrium (SFE) models of an oligopolistic electricity market. Both the affine supply function model and the piece-wise affine supply function model are considered. Different parametrization cases of the affine supply function model are analyzed. The piece-wise affine supply functions that have a large number of pieces are used to numerically estimate the equilibrium supply functions of any shapes. Simulation cases of the piece-wise affine supply function model with different peak loads, nonquadratic and nonconvex costs, and different demand elasticities are studied. An example based on the cost data from the real-world electricity industry is used to validate the approach presented in this paper. Simulation results show that the coevolutionary approach rapidly converges to SFE in the affine supply function model simulation and robustly converges to SFE in all cases of the piece-wise affine supply function model simulation. The approach is robust and flexible and has the potential to be used to solve the complicated equilibrium problems in real-world electricity markets. [ABSTRACT FROM AUTHOR]

The first of this two-paper series formulates a stochastic security-constrained multi-period electricity market clearing problem with unit commitment. The stochastic security criterion accounts for a pre-selected set of random generator and line outages with known historical failure rates and involuntary load shedding as optimization variables. Unlike the classical deterministic reserve-constrained unit commitment, here the reserve services are determined by economically penalizing the operation of the market by the expected load not served. The proposed formulation is a stochastic programming problem that optimizes, concurrently with the pre-contingency social welfare, the expected operating costs associated with the deployment of the reserves following the contingencies. This stochastic programming formulation is solved in the second companion paper using mixedinteger linear programming methods. Two cases are presented: a small transmission-constrained three-bus network scheduled over a horizon of four hours and the IEEE Reliability Test System scheduled over 24 h. The impact on the resulting generation and reserve schedules of transmission constraints and generation ramp limits, of demand-side reserve, of the value of load not served, and of the constitution of the pre-selected set of contingencies are assessed. [ABSTRACT FROM AUTHOR]

This paper proposes a method for choosing the best transmission system expansion plan considering a probabilistic reliability criterion (RLOLE). The method minimizes the investment budget for constructing new transmission lines subject to probabilistic reliability criteria, which consider the uncertainties of transmission system elements. Two probabilistic reliability criteria are used as constraints. One is a transmission system reliability criterion (RLOLETS) constraint, and the other is a bus/nodal reliability criterion (RLOLBus) constraint. The proposed method models the transmission system expansion problem as an integer programming problem. It solves for the optimal strategy using a probabilistic branch and bound method that utilizes a network flow approach and the maximum flow-minimum cut set theorem. Test results on an existing 21-bus system are included in the paper. They demonstrate the suitability of the proposed method for solving the transmission system expansion planning problem subject to practical future uncertainties. [ABSTRACT FROM AUTHOR]

A majority of states has taken steps to regulate the reliability of electricity service, and there is a current regulatory trend focusing on worst-performing feeders (WPFs). This paper performs a comprehensive assessment of worst-performing feeders at Midwest Energy by examining nine years of historical interruption data and validating statistical results with predictive modeling. The paper shows that historical data are able to reflect expected performance but are less able to reflect the risk of worse-than-expected performance. These results raise serious questions as to the usefulness of WPF lists in their present incarnation, and this paper provides recommendations on how utilities can better identify and manage poor-performing feeders. [ABSTRACT FROM AUTHOR]

This paper presents a simulation study about the co- ordination and interaction of advanced power electronic devices working in close electrical proximity. In particular, three major power quality devices (PQDs)--an advanced static VAR compensator, a dynamic voltage restorer, and a high-speed transfer switch as well as their combined performance--are modeled and studied in detail using ATP-EMTP. The paper addresses potential problems related to the PQD's combined operation, in addition to coordination issues. Comparison between simulation results and field measurements of individual PQD's are also presented. [ABSTRACT FROM AUTHOR]

There is increasing interest in the new deregulated electric utility environment in assessing the customer costs associated with failures in electric power supply and the responsibilities associated with these failures. The customer interruption cost when an electric supply failure occurs depends on many factors, such as the customer types interrupted, the actual load demand at the time of the outage, the duration of the outage, the time of day and the day in which the outage occurs. The absence of many of the data sets required in a detailed evaluation of the customer costs makes it difficult to estimate precise individual customer outage costs due to a specific failure event. This paper illustrates the development of approximate methods for event-based customer interruption cost evaluation on a distribution feeder subjected to a specific outage event. A series of approximate methods are presented and the outage cost estimates are compared with a set of base method results. The approximate methods are based on the use of customer sector data sets, i.e., commercial, industrial, residential data, which are generally available to most utilities. The paper also illustrates further simplifications of the approximate techniques which reduce the effort required to estimate the outage costs. The approximate techniques provide a practical approach to evaluating a specific outage event. [ABSTRACT FROM AUTHOR]

We present in this paper a short-term scheduling of battery in security-constrained unit commitment (SCUC). For economical operation and control purposes, electric power users with photovoltaic (PV)Ibattery systems are interested in the availability and the dispatch of PV/battery power on an hourly basis, which is a cumbersome task due to the complicated operating patterns of PV/battery. The details of battery model in the PV/battery system are presented in this paper. The paper applies a Lagrangian relaxation-based optimization algorithm to determine the hourly charge/discharge commitment of battery in a utility grid. The paper also applies a network flow programming algorithm for the dispatch of committed battery units. The paper analyzes the impact of grid-connected PV/battery system on locational pricing, peak load shaving, and transmission congestion management. An eight-bus test system is used to study the operational pattern of aggregated PV/battery and demonstrate the advantages of utilizing PV/battery systems in the electric utility operation. [ABSTRACT FROM AUTHOR]

This paper simulates a pool-based electricity market and identifies equilibrium patterns. A multiperiod framework that requires the use of continuous and binary variables is considered. Producers can be either price-takers or price-makers, although price-makers and their behavior characterize the market. The elasticity of the loads is modeled through piecewise constant price-demand curves. The market operator uses a detailed network-constrained market-clearing auction that results in hourly market-clearing prices. The behavior of the market participants and the market itself are characterized through a repetitive simulation procedure. The tool presented in this paper is particularly useful for the market regulator that may use it to monitor the market and to identify the exercise of market power by producers. Results from a realistic case study arc presented and discussed. [ABSTRACT FROM AUTHOR]

The efficient location identification of multiple line outages is critical to not only cascading failure elimination but also repair cost reduction. Most of existing methods, however, fail to handle location identification well. This failure typically occurs because the methods cannot overcome two challenges: the very limited number of phasor measurement units (PMUs) and the high computational complexity. This paper presents an efficient algorithm inspired by the ambiguity group theory to identify the locations of line outages with limited PMUs. Using 14-, 57-, 118-, 300-, and 2383-bus systems, our experimental study demonstrates that the proposed technique successfully identifies the most likely multiple line outages while attaining a 500 \times speedup when compared to the method of exhaustive search. [ABSTRACT FROM PUBLISHER]

Rotor winding interturn short-circuit (RWISC) occurring in turbine generators has been plaguing power producers with respect to production safety and economy. RWISC is characterized by impaired fundamental component of the exciting magnetomotive force and resultantly reduced no-load electromotive force E0. In this paper, an inverse reasoning method is proposed to analyze RWISC. First, it is assumed that the generator's rotor winding is running in good condition and the generator's electromagnetic power (virtual power, VP) is inversely calculated from the obtained operational data on generators. Second, the difference between the virtual power and the actual electromagnetic power is calculated and then used to determine whether an RWISC occurs on the turbine generator. Three real cases of severe rotor winding shorts have demonstrated that this method proposed in this paper not only enables to diagnose RWISC, but also allows determining the RWISC level and its trending accurately. The method is appropriate for RWISC diagnosis, whether offline or online, and can be applied to make the generator sets in the power plant run safer, more economical, and more stable. [ABSTRACT FROM AUTHOR]

The penetration of variable renewable energy sources, the deregulation of electricity markets, and the expansion of HVDC-transmission capacities all increase the variability, uncertainty, and imbalances for system operators (SOs) to handle. Meanwhile, frequency quality has deteriorated and occurrence of balancing problems has increased. Therefore, there is an increased need for SOs to improve their balancing strategies. In this paper, we present a new balancing evaluation framework. The main idea of the framework is to be applicable for real and large power systems and provide support for SOs when comparing already used balancing strategies with new ones using historical available data. This is important as only comparatively low-resolution data measurements such as hourly mean values for production, consumption, and HVDC transmission are stored in many power systems. The framework consists of model building, system parameter identification, testing different strategies, and targets supporting the corporate missions of the SOs. In a case study, the framework is tested for a real power system where the model setup mimics measured frequency accurately. The case study illustrates how the framework can be used to evaluate the impact of different balancing strategies on a series of selected targets, which support the cooperate missions of ENTSO-E. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of price multiplicity in network-constrained pool-based electricity markets under marginal pricing. This problem consists in the existence of multiple vectors of locational marginal prices for the same optimal market-clearing dispatch solution. As a consequence, delicate conflicts of interest may arise among market participants. Price multiplicity may take place even in auction designs based on convex formulations for the market-clearing procedure. An effective duality-based solution approach is proposed in this paper to handle the issue of price multiplicity. Once the optimal market-clearing dispatch is known, we propose the subsequent solution of a simple pricing problem in order to determine the vector of locational marginal prices. Unlike previously reported methodologies, the proposed approach presents two salient features: 1) it is based on sound mathematical programming, and 2) it is computationally inexpensive since it relies on the solution of a linear program. Numerical results are provided to illustrate the performance of the proposed tool. [ABSTRACT FROM PUBLISHER]

This paper deals with the prediction of residual demand curves in electricity spot markets, as a tool for optimizing bidding strategies in the short-term. Two functional models are formulated and empirically compared with the naïve method, which is the reference model in most of the practical applications found in industry. The first one is a functional nonparametric model that estimates the residual demand as a function of past residual demands, while the second one uses also electricity demand and wind power forecasts as explanatory variables. The proposed models have been tested using real data from the Spanish day-ahead market over a period of two years. The analysis of these results has motivated the development of a new forecasting strategy based on the selective combination of forecasts, taking advantage of the effect of wind fluctuations on the residual demand. This new forecasting approach outperforms the naïve method in all circumstances. [ABSTRACT FROM PUBLISHER]

In an electricity market, the main goal of a generation company (GenCo) is to maximize its profit, while encountering the uncertainty of the electricity price forecast. Different risk measures have been proposed to cope with this source of uncertainty. However, those are usually before-the-fact performance indices and cannot give a measure for the financial loss/gain (FLG) of a GenCo considering the electricity prices actually realized in the market. This paper focuses on this matter. The time series of FLG is first constructed given the real conditions of the electricity market. Then, the FLG time series is quantized using Silhouette criterion and k-means clustering approach. Subsequently, based on the historical values of the quantized FLG time series and relevant exogenous variables, its day-ahead values are predicted. The method proposed for day-ahead FLG prediction consist of conditional mutual information and sequential forward search as the feature selection technique and extreme learning machine as the forecasting engine. The effectiveness of the whole proposed approach, including the FLG time series construction, quantization approach, and the prediction method, is shown for a typical GenCo using the real data of the PJM and Ontario electricity markets. [ABSTRACT FROM PUBLISHER]

Implementing automation system in distribution networks needs a huge investment that usually cannot be funded entirely in a short period of time. So distribution companies (DISCOs) should develop long-term plans to equip their network with automation technologies as far as economically justifiable. Aiming to provide a methodology for development such plans, this paper presents a novel multistage planning model for implementing distribution automation system considering all main hardware and software infrastructures. The proposed method optimally determines the type, location, and time in which an equipment or infrastructure must be added to network considering the network capacity expansion plan. The objective function of the planning problem is to maximize the net present value of the DISCO's profit in the planning time horizon. In this method, the optimization problem is solved using the genetic algorithm approach as a promising technique in solving the mixed integer nonlinear programming problems. The proposed method is evaluated on an illustrative test network and the obtained results are presented and discussed. [ABSTRACT FROM PUBLISHER]

The deepening penetration of distributed energy resources into distribution networks (DNs) is causing relevant issues to be addressed by distribution system operators (DSOs), such as quality of service, security and safety, both at medium-voltage and low-voltage distribution levels. This paper presents how Unareti SpA, an Italian DSO, has addressed those challenges launching a set of research activities in different areas of distribution automation. Results collected during field experiences have been used to design the reference model of the next generation of DN secondary substations. [ABSTRACT FROM PUBLISHER]

The smart substation, revolutionarily changing every aspect of the modern substation, is developing fast in the world and being massively deployed in China quickly. A smart substation is typically implemented with a sophisticated combination of smart primary high-voltage equipment and hierarchically networked secondary devices. Based on the IEC61850 communication protocol, the functionalities, such as the information sharing and interoperability among smart electric equipment, are realized in smart substations. It is regarded as the basis for the development of smart grid and represents the future development trend of substation technologies. This paper reviews the fundamental vision of the smart substation. The state of the art and the challenges encountered in the practice of engineering implementation are presented. Future developments to solve the present challenges and promote the development of smart substations are also described. [ABSTRACT FROM PUBLISHER]

This paper presents a novel way to model the generation capacity expansion problem in a liberalized framework via a multi-year bilevel equilibrium model. In the upper level the competing generation companies maximize their individual profits, while the lower level represents the market using a conjectured-price response approach, which allows us to vary the strategic spot market behavior, to see how much the reigning competitive behavior impacts investment decisions. The bilevel equilibrium model is formulated as an equilibrium problem with equilibrium constraints, transformed into a mixed integer linear program and solved as such using diagonalization in order to verify equilibria. We present a case study to apply this new modeling approach and to demonstrate that the proposed equilibrium problem with equilibrium constraints can have multiple solutions whose respective investments can vary. [ABSTRACT FROM PUBLISHER]

In centralized day-ahead electricity markets with marginal pricing, unit commitment costs and capacity constraints give rise to non-convexities which may result in losses to some of the participating generating units. To compensate them for these losses, a recovery mechanism is required. In Part I of this two-part paper, we present certain recovery mechanisms that result in recovery payments after the market is cleared. We also propose a methodology for evaluating the bidding strategy behavior of the participating units for each mechanism. In this paper (Part II), we apply this methodology to evaluate the performance and incentive compatibility properties of each recovery mechanism on a test case model representing the Greek joint energy/reserve day-ahead electricity market. Lastly, we perform sensitivity analysis with respect to key parameters and assumptions and we provide directions for further research. [ABSTRACT FROM PUBLISHER]

Reserve services are an essential part of a standard market design and are under development in major electricity markets. This paper presents the development of differential evolution algorithm for optimal allocation of energy and spinning reserve. The optimization is performed in an integrated market with biddable spinning reserve and sectional price offer curves while considering all security and power systems constraints in steady state and system credible contingencies. The effectiveness of the proposed method is examined by application of the proposed algorithm on the IEEE 30-bus test system. Some comparisons are made with analytical and evolutionary methods in various cases. [ABSTRACT FROM PUBLISHER]

A Reference Network Model (RNM) is a large-scale distribution planning tool that can help regulators to estimate efficient costs in the context of incentive regulation applied to distribution companies. This paper presents the main features of an RNM developed for planning distribution networks from scratch, greenfield planning, or incrementally from an existing grid. Two properties of the model are highlighted: the simultaneous planning of high-, medium-, and low-voltage networks by using simultaneity factors; and the layout of cables in urban areas, taking into consideration the street map, which is automatically generated by the model. A case study evaluates the impact of these features on the results. [ABSTRACT FROM AUTHOR]

This paper proposes a chance constrained formulation to tackle the uncertainties of load and wind turbine generator in transmission network expansion planning. A combined Monte Carlo simulation/analytical probabilistic power flow analysis method is first presented to obtain the probability density function of wind turbine generator output. The paper then shows the development of the chance constrained formulation with the inclusion of the wind turbine generator probability density function and probabilistic power flow in the formulation. The proposed formulation is more computationally efficient and can deal with uncertainties in transmission network expansion planning. The power of the new method is shown through the application of the formulation to two test systems. [ABSTRACT FROM AUTHOR]

The implementation of demand-response programs (DRP) has gained interest as a means to alleviate energy consumption during peak-hours. Two explanations account for the success of such programs which involve both utilities and electricity consumers, with the latter often organized into coalitions: the system operator meets its goal of reducing the load peak; simultaneously, electricity consumers achieve economic benefits when reducing consumption during peak hours. In this paper, a Monte Carlo-based algorithm has been proposed for the formulation of multiple purchase offers in the day-ahead energy market (DAEM) by coalitions in which consumers vary in their sensitivity to DRP, manifesting different responsiveness to hourly tariffs based on the hourly market clearing prices. Being able to monitor how coalition members use air-conditioning in the presence of variable hourly energy tariffs, the coordinator can then define a purchase-bidding strategy, depending on how price-sensitive the coalition is. Simulation results show that the presence of a price-sensitive demand leads not only to a subsequent reduction in energy prices during peak-hours but also leads to a decrease in their inter-hour volatility. [ABSTRACT FROM AUTHOR]

It is widely agreed that an increased participation of the demand side in the electricity markets would produce benefits not only for the individual consumers but also for the market as a whole. This paper proposes a method for quantifying rigorously the effect that such an increase would have on the various categories of market participants. A new centralized complex-bid market-clearing mechanism has been devised to take into consideration the load shifting behavior of consumers who do submit price-sensitive bids. The effects of the proportion of demand response on the market are illustrated using a test system with ten generating units scheduled over 24 periods. [ABSTRACT FROM AUTHOR]