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We present a computationally improved heuristic algorithm for transmission switching (TS) to recover load shed. Research from the past showed that changing power system topology may control power flows and remove line congestion. Hence, TS may reduce the required load shed. One of the main challenges is to find a potential TS candidate in a suitable time. Here, we propose a novel heuristic method that is capable of finding the potential TS candidate faster than existing algorithms in literature. The proposed method is compatible with both the AC and DC optimal power flows (OPF). Three metrics are used to compare the proposed algorithm with the state-of-the-art from literature to show the speedup and accuracy achieved. The proposed method is implemented on the IEEE 30-bus system, PEGASE 89-bus system, IEEE 118-bus system, and Polish 2383-bus system. The results on the large-scale Polish 2383-bus system shows that the proposed algorithm is scalable to large real-world systems. Parallel computing is implemented to further improve the computational performance of the proposed algorithm.

INFLUÊNCIA DO CANHÃO FINAL NA DISTRIBUIÇÃO DE PRESSÃO E VAZÃO DA LINHA LATERAL DE UM PIVÔ CENTRAL VICTOR BUONO DA SILVA BAPTISTA1; ALBERTO COLOMBO2; THIAGO HENRIQUE BURGARELLI TEIXEIRA3; PIETROS ANDRÉ BALBINO SANTOS4; ADRIANO VALENTIM DIOTTO5 E LESSANDRO COLL FARIA6 1 Professor Assistente, Departamento de Engenharia, Universidade Federal de Lavras, Campus Universitario, s/n, Caixa Postal 3034, CEP 37200-000, Lavras, MG, Brasil. Email: victor.buonosb@ufla.br 2 Professor Titular, Departamento de Recursos Hídricos e Saneamento, Universidade Federal de Lavras, Campus Universitario, s/n, Caixa Postal 3034, CEP 37200-000, Lavras, MG, Brasil. Email: acolombo@ufla.br 3 Doutorando, Programa de Pós-graduação em Recursos Hídricos, Universidade Federal de Lavras, Campus Universitario, s/n, Caixa Postal 3034, CEP 37200-000, Lavras, MG, Brasil. Email: teixeira.agricola@gmail.com 4 Doutorando, Programa de Pós-graduação em Recursos Hídricos, Universidade Federal de Lavras, Campus Universitario, s/n, Caixa Postal 3034, CEP 37200-000, Lavras, MG, Brasil. Email: pietros.balbino@gmail.com 5 Professor Adjunto, Departamento de Recursos Hídricos e Saneamento, Universidade Federal de Lavras, Campus Universitario, s/n, Caixa Postal 3034, CEP 37200-000, Lavras, MG, Brasil. Email: adriano.diotto@ufla.br 6 Professor Associado, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas, Rua Gomes Carneiro, Centro, CEP 96010-610, Pelotas, RS, Brasil. Email: lessandro.faria@ufpel.edu.br 1 RESUMO O objetivo deste trabalho foi analisar a influência da presença do canhão final, com diferentes vazões, na distribuição de pressão e vazão da linha lateral de um sistema de irrigação do tipo pivô central utilizando o simulador hidráulico EPANET em comparação com um modelo analítico. Foram realizadas simulações de uma linha lateral do pivô central, localizado em Lavras/MG, com a inserção de um canhão final fictício de altas vazões. Houve também a diminuição do diâmetro da linha lateral, visando provocar maior perda de carga. Os resultados obtidos pelo EPANET foram comparados com resultados determinados a partir de um método analítico. Dessa forma, este estudo demonstrou a influência do acréscimo de vazão na distribuição de pressão da linha lateral do pivô central, devido à presença do canhão final. Os resultados também demonstraram a qualidade da simulação hidráulica do EPANET, que apresentou desvio relativo máximo de 1% em relação ao método analítico. Keywords: simulação hidráulica, distribuição de pressão, EPANET, modelagem. BAPTISTA, V. B. S.; COLOMBO, A.; TEIXEIRA, T. H. B.; SANTOS, P. A. B.; DIOTTO, A. V.; FARIA, L. C. INFLUENCE OF END GUN IN THE PRESSURE AND FLOW RATE DISTRIBUTION OF A CENTER PIVOT LATERAL LINES 2 ABSTRACT The aim of this work was to analyze the influence of the presence of the end gun, with different flow rates, on the pressure distribution and lateral line flow of a center pivot irrigation system using the EPANET hydraulic simulator compared to an analytical model. Simulations were performed on center pivot lateral line located in Lavras/MG. In the simulations was inserted an end gun operating under high flow. There was also decrease lateral line diameter aiming to cause greater head loss. The results obtained were compared with the use of EPANET parameters and with an analytical method. Thus, this study showed the influence from flow increase in the pressure distribution of the pivot lateral line, since there was an end gun in the end of the lateral. The results also demonstrated a satisfied estimative of EPANET's hydraulic theory. Keywords: hydraulic simulation, pressure distribution, EPANET, modeling.

In this paper, we analyze the operational revenue insufficiency of generators for future high renewable energy scenarios. The “missing money” problem originates from flaws in energy price formulation in competitive wholesale electricity markets and is directly tied to revenue sufficiency. In addition to fundamental market inefficiencies, the problem is amplified by low and near-zero marginal cost generation and its variability. Low marginal cost generation has depressive impacts on electricity prices in energy markets, which can widen the gap. Here, we analyze the operational revenue of three future renewable scenarios under a DC optimal power flow (OPF) (without losses) and AC optimal power flow (OPF) (with losses) locational marginal price (LMP)-based market without line flow constraints. Simulations are shown for a modified IEEE-30 bus test network with high renewable penetration. Results indicate a decrease in profit for fossil-fuel generators as renewable penetration increases and a slight overall increase in the variance of profits under AC versus DC OPF.

Increasingly severe wildfires pose significant dangers to ecological, social, and economic systems. To curtail the risk of igniting wildfires, California utilities employ the Public Safety Power Shutoff (PSPS) program, which de-energizes transmission lines that run through wildfire-prone regions. In order to reduce the amount of load shedding required during PSPS events, this paper explores the use of dynamic line ratings (DLR) to manage the current flows on lines that pose a high risk of igniting wildfires. DLR schemes determine line flow limits that change with ambient conditions. This paper uses DLR in combination with more restrictive ground clearance requirements during wildfire-prone conditions to reduce the likelihood of wildfire-igniting faults from conductors contacting vegetation. Using two case studies, this paper demonstrates the potential benefits of DLR in this context by comparing the tradeoffs between completely de-energizing lines versus imposing more stringent ground clearance requirements via reducing current flows with DLR. Results from a large dataset representing WECC with actual data regarding ambient conditions, load demands, and wildfire risks show that the proposed approach can significantly reduce load shedding due to de-energizing lines that pose high risks of igniting wildfires.

Transmission line capacity ratings are often treated as a fixed nominal value; however, these ratings can be temporarily increased to a higher rating that can be leveraged when accounting for uncertainty in the system. In this paper, we introduce a chance constrained optimal power flow model to account for fluctuations in wind power generation with respect to line flow ratings. We propose a two-stage stochastic program where the optimal traditional generator dispatch is determined across wind power fluctuation scenarios. Flexible line flow ratings are incorporated into our model using integer chance constraints which limit the probability of non-nominal line capacity rating violations across all wind scenarios. We present simulation results on the RTS-GMLC test system to demonstrate the effectiveness of considering infrequent line violations on network congestion to reduce the total average wind power curtailment by 15%.

There has been a growing trend toward endovascular intervention to improve peripheral flow in patients with peripheral arterial disease. To date, there is no clear consensus regarding timing of lower-extremity amputations after revascularization. The purpose of this study was to evaluate the effects of timing between endovascular intervention and minor lower-extremity amputations and its influence on wound healing and limb loss within 1 year. A secondary purpose was to evaluate the impact of restoring in-line flow on healing rates. A total of 310 patients who underwent endovascular intervention and a minor lower-extremity amputation within 90 days were included in the study. Healing rates were defined as optimal, delayed, or failure. There was a statistically significant difference between patients with optimal healing to delayed healing and amputation ≥30 days after endovascular intervention (p = .037). We found no difference in healing rates in regard to amputation timing when examining patients who ultimately healed versus patients who failed to heal (p = .6717). Absence of in-line flow (p = .0177), male sex (p = .0090) and diabetes mellitus (p = .0076) were statistically significant factors for failing to heal. Presence of infection (p ≤ .0001) and wound dehiscence (p ≤ .001) were also associated with a failure to heal. End-stage renal disease trended toward significance for failing to heal (p = .065). Amputation-free survival at 1 year after endovascular intervention and pedal amputation was 76.8% (n = 238). Our findings suggest that in the absence of infection, performing minor lower-extremity amputations 15 to 60 days after endovascular intervention may allow for improved healing. Absence of in-line flow, male sex, diabetes mellitus, postoperative infection, and wound dehiscence are significant factors for failure.

An outage detection framework for power distribution networks is proposed. Given the tree structure of a distribution system, a detection method is developed combining the use of real-time power flow measurements on the edges of the tree with load forecasts at the nodes of the tree. The maximum likelihood detection decision for an arbitrary number of outages is shown to be efficiently computable due to decoupling across local areas determined by the sensor locations. To minimize the maximum missed detection probability, the optimal sensor placement is efficiently computed as well. Finally, a set of case studies is conducted using feeder data from the Pacific Northwest National Laboratories. It is shown that $10\%$ mean detection error probability can be achieved by a sensor density of $30\%$ for a typical feeder with the proposed optimal sensor placement and outage detection methods.

Integrated system preventive maintenance is an exigent job in both regulated as well as deregulated utility systems that must be carried over by the utilities in order to extend their continuation and performance. The generator maintenance scheduling is commonly focused, but the line flow limits in the transmission lines, which are connected to the generating units may violate due to the outages. Thus, maintenance planning of generators and transmission lines has become indispensable and the Integrated Maintenance Scheduling (IMS) addresses alike. Inclusion of transmission lines and line flow constraints in generating unit maintenance will increase intricacy of the problem that enforces IMS for secure and economic operations. As an efficient optimization tool is necessary, the modern bio inspired algorithm, Ant Lion Optimizer (ALO) has been intended for the first time to address the IMS problem. The well-known / standard test systems are used for demonstration and the attained numerical results by simulation are compared with other meta-heuristic methods. The comparison reveals that the ALO is a positive choice for solving IMS problems.

The on-wall structures in an attachment-line flow are discussed based on an exact solution of the Navier–Stokes (NS) equations, focusing on distinct features of skin friction, surface pressure, and boundary enstrophy flux (BEF) and intrinsic connections between them.

This paper presents a TEP problem solution technique based on bat algorithm for standard 6 bus system and a real system of 400 kV, WBSEDCL. The objective of the work is to reduce the cost of proposed new lines for economic and reliable supply. DC power flow has been used to maintain the power balance at buses and line constraints. The line flow constraints are considered while optimizing the objective function. The method has been successfully applied to the system and satisfactory results have been found.

Outage Detection method for radial distribution networks uses demand forecasting based on historical load data of the system and real time line flow measurements. The line flow measurements are obtained from sensors placed on certain nodes of the system to predict the location of the outage. Hypotheses are created for outage at each node as covariance matrix between forecasted demand and the real time line flow data. A Backward Forward Sweep (BFS) load flow is performed to obtain line flow sensor measurements in the nodes at which the sensors are installed. The system is decoupled into areas based on sensor placement to reduce the computation. Outage is located by identifying the area in which outage has occurred and then evaluating all the outage hypotheses under the area. This method is computationally efficient as minimal number of outage hypotheses are evaluated.

Industrial estates in Thailand, which are usually connected to distribution systems, allow power producers to directly negotiate with their own customers. Therefore, distribution utilities have to calculate wheeling charges with fairness and transparency. This paper proposes a concept of wheeling charge calculation based on “power flow based MW-Mile method” with the consideration of differentiation of line flow magnitude before and after the power transaction. The results show that the proposed concept computes the different wheeling charge against existing power flow based MW-Mile method and can reflect an increase or decrease of line flow due to power transaction.

In practice, sensitivity matrixes were generated through multiple load-flow analysis, though some literature shows the sensitivity like GSF (Generator Shift Factors) can be calculated through conventional numerical method without using load flow analysis. This paper presents the comparative results of locational marginal pricing on IEEE 7 bus system using both PTDF (Power Transfer Distribution Factors) based on DC load flow and Numerical conventional GSF matrix. The analysis shows the effect of GSF on congestion charges and the losses in the system and their formulation and formation of total locational pricing scheme. This paper further gives a combined pricing based on LMP (Locational Marginal Pricing). The prime goal of this paper is to get a better line flow and less locational marginal pricing.

Transmission CA (TCA), a powerful function in EMS, is to help system operators maintain the security of a TPS. It simulates the post-contingency power flow of the TPS and activates alarms if operational limits of some components (e.g., bus voltage magnitude limits or line flow limits) are violated in a contingency.

This paper addresses the presenting and implementation of a composite performance index (PI) for contingency analysis to identify critical components (lines and/or generation units), initiating event, shortest path for cascading, and cascading chains. The proposed PI has obtained in terms of thermal transfer capacity of transmission lines, bus voltage profile, generation units active and reactive power. The proposed index offers a simple method to identify and rank critical contingencies in an efficient way. It assesses the development of cascading outages by categorizing and visualizing of cascading events. The proposed PI is immune to masking effect irrespective of the network topology and loading condition. As a diagnostic tool, the proposed index capable of identifying the location of limits violation (bus voltage, line flow, generator active and reactive power) inside the network, for feasible corrective control actions, and it can be added to existing contingency analysis tools in order to evaluate the impact of contingency event, whether on-line or offline. Extensive simulations have been carried out using 6-bus, and IEEE 14-bus systems and all results ensure the robustness and effectiveness of the proposed PI in contingency analysis.

This paper presents a FACTS operation scheme to enhance the power system security. Three main generic types of FACTS devices are introduced. Line overloads are solved by controlling active power of series compensators and low voltages are solved by controlling reactive power of shunt compensators, respectively. Especially, the combined series-shunt compensators such as UPFC are applied to solve both line congestions and low voltages simultaneously. Two kinds of indices that indicate the security level related to line flow and bus voltage is utilized in this paper. They are iteratively minimized to determine operating points of the devices for security enhancement. The sensitivity vectors of the indices are derived to determine the direction of minimum. The proposed algorithm is verified on the IEEE 14-bus system with FACTS devices in a normal condition and in a line-faulted contingency.

This paper presents a load shedding algorithm for alleviating line overloads employing Teaching learning based optimization (TLBO). The buses are selected for load shed based on the sensitivity of severity index with respect to load shed. Load shed is based on the next interval predicted load which could cause emergency situation from thermal limit consideration. Line flow constraints have not only considered for next predicted interval but in present base case loading conditions also. Optimum load shed at the selected buses have been obtained for 30-bus, 39-bus standard test systems. Further another technique modified version of bare bones particle swarm optimization known as (BBExp) has been used to validate the algorithm for load shedding.

This paper describes a method for alleviation of line over load in a line by regulation power flow in another line having Series Power Flow Controller (SPFC). For this purpose, the sensitivity relations between the line flow of the line with SPFC and the over loaded line are determined. These sensitivity relations are used to determine the required amount of change in power flow at the line with SPFC to reduced power flow of the over loaded line. IEEE 30 system is used to verify the applicability of the proposed method.

Biomimetics is a promising field of research in which natural processes and structures are transferred to technical applications. The lateral line is a critical component of the fish sensory system and plays an important role in many behaviors by providing hydrodynamic information about the surrounding fluid. It is believed that the artificial lateral line flow sensors (ALLFS) are advantageous for underwater applications. This paper reviews the morphology and biophysics of the lateral line, especially theoretical models of lateral line, including biomechanical model, frequency response and time domain response of lateral line. Also, this paper reviews some efforts to mimic lateral line system in recent years. In order to capture the recent research status, this paper reviews the design and fabrication of ALLFS based on different sensing principles. Further researches to develop ALLFS and their underwater applications are also discussed in this paper.

Line flow is one of the key factors which dominate the power system security. To deal with this problem, this paper proposed a method of power system assessment and control based on power system Line flow risk. Probabilistic power flow (PPF) is used to analyze the random of system statuses. The severity function is used to describe the impact of the transmission line load. Line flow risk is defined as the result of the probability multiplying the severity of Line flow. It is an indicator of power system security. This reduces the system line flow risk and increases the system security.

This paper defines flow control algorithms for loop flow cancellation based on the allocation and tracing of bilateral transactions and loop flows. In Part I of this paper, we have shown that the main difference between transportation and electrical networks is caused by the existence of loop flows. We have introduced a distributed framework for the modeling and tracing of bilateral transactions and the corresponding loop flows. Its zooming-out capability provides a valuable mechanism for representing external (inter-area) loop flows based on simplified topologies of individual areas. The tracing information accurately allocates bilateral transactions with associated contract paths to line flows and loop flows. Furthermore, this information can be used for determining the set points of control equipment so that loop flows are minimized. In this framework, phase angle regulators (PARs), commonly used for line flow control, are represented through their effects on loop flows. We define sufficient conditions for achieving complete loop flow cancellation. A new distributed algorithm for determining PAR set points in a coordinated way without revealing operating conditions of individual areas is introduced in this part. Finally, complete loop flow cancellation and the distributed algorithm for finding PAR set points are demonstrated in the Reliability Test System (RTS) 96-bus system with wheeling loop flows.

Directed Self Assembly (DSA) of block-copolymers (BCPs) used as a complementary technique to the 193nm immersion lithography has demonstrated sub-10nm node applications in both via and line/space patterning. We propose however to study the performance of graphoepitaxy which allows DSA with thicker initial BCP layer, higher multiplication factors and stronger orientation control of lamellae. The aim of this work is to use the 300mm pilot line available at LETI and Arkema’s advanced materials to evaluate the performances of a novel graphoepitaxy process based on the work on a 38nm period lamellar PS-b-PMMA (L38) reported before.

Classification of bandwidth-heavy Internet traffic is important for network administrators to throttle network of heavy-bandwidth applications traffic. Statistical methods have been previously proposed as promising method to identify Internet traffic based on packet statistical features. The selection of statistical features still plays an important role for accurate and timely classification. In this work, we propose an approach based on feature selection methods and analytic methods (scatter, one-way analysis of variance) in order to provide optimal features for on-line P2P traffic detection. Feature selection algorithms and machine learning algorithms were implemented using WEKA tool for available traces from University of Brescia, University of Aalborg and University of Cambridge. Experimental results show that the proposed method is able to achieve up to 99.5% accuracy with just six on-line statistical features. These results perform better than other existing approaches in term of accuracy and the number of features.

Reliability evaluation of composite systems involves extensive calculations. Current solutions to this computational burden have mainly focused on extracting failure states from the state space. Instead, the evaluation of failure states is accelerated by methods presented in this paper. The scale of optimizations required for generation redispatching and/or load shedding in failure states is reduced by eliminating redundant line flow constraints. First, a sufficient and necessary condition for a line flow constraint to be redundant is established in the form of a linear programming problem, based on the concept of steady-state security region (SSR). Then, two redundancy elimination methods are proposed-a conservative one based on a heuristic, and a radical one based on an analytical condition. Numerical tests are conducted on IEEE-RTS79 and a real-life system. More than half of the line flow constraints are eliminated by the conservative method and nearly 90% by the radical method. The proposed methods can be used in conjunction with most of the existing acceleration techniques to further improve efficiency.

This paper presents Hybrid Particle Swarm Optimization (HPSO) technique to solve the Optimal Load Dispatch (OLD) problems with line flow constrain, bus voltage limits and generator operating constraints. In the proposed HPSO method both features of EP and PSO are incorporated, so the combined HPSO algorithm may become more effective to find the optimal solutions. In this paper, the proposed Hybrid PSO, PSO and EP techniques have been tested on IEEE14, 30 bus systems. Numerical simulation results show that the Hybrid PSO algorithm outperformed standard PSO algorithm and Evolution Programming method on the same problem and can save considerable cost of Optimal Load Dispatch.

This paper presents an algorithm for solving Security Constrained Economic Dispatch (SCED) problem through the application of Tabu Search (TS). The SCED problem is formulated with base case and contingency case line flow constraints, which are important for practical implementation. One representative system namely IEEE-57 bus system is taken for investigations. The SCED results obtained using TS are compared with those obtained using Genetic Algorithm (GA), quasi-Newton method (QN), and Mat-Power.

This paper proposes an artificial bee colony (ABC) algorithm for solving optimal power flow (OPF) problem. The objective of the OPF problem is to minimize total cost of thermal units while satisfying the unit and system constraints such as generator capacity limits, power balance, line flow limits, bus voltages limits, and transformer tap settings limits. The ABC algorithm is an optimization method inspired from the foraging behavior of honey bees. The proposed algorithm has been tested on the IEEE 30-bus, 57-bus, and 118-bus systems. The numerical results have indicated that the proposed algorithm can find high quality solution for the problem in a fast manner via the result comparisons with other methods in the literature. Therefore, the proposed ABC algorithm can be a favorable method for solving the OPF problem.

In the present work, intelligent approach is presented for the placement of distributed generation (DG) unit in order to relieve congestion in transmission lines. Loss flow index is employed to find the optimal locations for the incorporation of DG unit to the existing network. The index presented in this work is based on mathematical form of real power losses which is drawn from conventional power flow solution. The proposed method of obtaining optimal placement is applied on IEEE 30 bus system, and obtained results are compared with respect to DGs. The suboptimal places are also determined in view of geographical suitability of the DG installation with respect to the optimal location. Results conveyed that the approach of optimal placement is good enough in comparison to other approaches presented in the past literature.

This manuscript shows the relationship between defectivity of a typical chemo-epitaxy sequence and the DSA-specific materials, namely the mat, the brush and the block co-polymer. We demonstrate that the density of assembly defects in a line-space DSA flow, namely the dislocations and 1-period bridges have a direct correlation to certain parameters in the synthesis sequence of these materials. The primary focus of this manuscript is on identifying, controlling and reproducing the defects-critical parameters in the block co-polymer synthesis process for a stable and low defect performance of DSA flows.

This paper investigates voltage stability of the power system during steady state and transient conditions. The voltage stability enhancement is achieved by utilizing FACTS devices at the best location of the system. The weakest bus in the system is the best location to implement shunt compensation device. In this paper, the weakest buses are identified via a fuzzy technique that utilizes two critical indices: Line Flow Index (LFI) and Voltage Profile Index (VPI) during normal and fault conditions. These indices are used to evaluate Criticality Index (CI) using Fuzzy rules, and thus, the system buses are ranked. Remedial actions are discussed to enhance the power system voltage stability by using FACTS devices (SVC and STATCOM) at the most vulnerable system buses. The results of this study show that the (STATCOM) performance is preferable to that of the (SVC) during fault conditions.

On-line critical contingency selection and ranking based on a composite security index is presented in this article. A new method for obtaining a composite scalar index, in terms of both line flow and bus voltage limit violations, has been developed based on the concept of hyper-ellipse inscribed within a hyper-box. The proposed index provides an efficient method for filtering and ranking the credible contingencies and is defined in such a way that a proper differentiation between the secure and insecure states are possible. The composite security index can completely eliminate the masking problem in contingency selection and ranking. In addition, it is seen that if the system is insecure, the exact location of limit violations in buses and branches can be determined by monitoring the violation vector so that proper preventive and corrective control actions can be taken. Extensive simulations have been done using IEEE 30-bus and IEEE 118-bus systems, and the results show that the proposed approac...