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Large-scale integration of inverter-based renewables is displacing synchronous machine generation, causing a reduction in the inertia of electrical power systems. This reduction is reflected in an increase in the rate of change of frequency (RoCoF). Additionally, the variation of the RoCoF will depend on the uncertainty associated with the generation of non-conventional renewable energy sources. For the planning of the operation of the system, it is essential to know the range of variation of the RoCoF when there are disturbances in the system and uncertainties in the generation of non-conventional sources of renewable energy. This paper proposes to establish the calculation of a confidence interval of the RoCoF variation that considers these uncertainties. So, this paper proposes a method to consider these uncertainties based on the probabilistic point estimate method (PEM); considering multiple renewable non-conventional sources with correlated or uncorrelated behavior in their powers injected into the system. On the other hand, as there are different proposals to calculate the RoCoF, this paper presents the application of the uncertainty model with three different RoCoF proposed calculation methods.

This paper presents a research context on the virtualization of phasor measurement units (PMUs) and real-time power grids simulation with state estimation. In this research, real-time simulation is introduced to use powerful features for validating state estimation solutions with PMUs. Virtual and online measurement equipment are reviewed in this manuscript to develop an innovative integration of the OpenPMU incorporated with a real-time simulation power grid and additional virtualized PMUs. The implementation of the platform has useful features within the infrastructure that allows the user to reproduce a detailed modeled power grid with simulation software. The use of real-time simulation tools brings several possibilities for improving testing and prototype assessment with higher precision in different applications. In this case, 2 tests power systems are evaluated by realistic integration of IEC61850-9-2 data utilization to observe the performance of a customized state estimation approach. The study implements a versatile methodology for commissioning OpenPMU devices, interacting simultaneously with additional virtual PMUs within the same simulation through sampled values (SV) to validate the measurement frames and assess the estimation with the generated data. Finally, the proposed work identifies the potential of virtualizing PMUs and the features of the OpenPMU applied to state estimation in conjunction with real-time simulation data.

O sistema nervoso parassimpático atua na regulação do tônus broncomotor, a maior parte dos nervos autônomos nas vias aéreas humanas são ramos do nervo vago, cujas fibras eferentes pré-ganglionares entram no pulmão no hilo e viajam ao longo das vias aéreas até o pulmão. Os antagonistas muscarínicos, também conhecidos como agentes anticolinérgicos, são broncodilatadores eficazes usados no tratamento da doença pulmonar obstrutiva crônica, usados para aliviar a dispneia e melhorar a tolerância ao exercício. Os antagonistas muscarínicos inalados interrompem a broncoconstrição induzida pelo vagal. O brometo de ipratrópio é um amônio quaternário inalado que bloqueia todos os três receptores muscarínicos, e outros antagonistas muscarínicos de ação prolongada bloqueiam predominantemente os receptores M1 e M3. Apesar do impacto mínimo do ipratrópio e do tiotrópio na frequência cardíaca e na pressão arterial, os dados são conflitantes em relação aos possíveis efeitos cardiovasculares adversos desses agentes em pacientes com DPOC.

The continuous development of DC technology and its increasing implementation in projects, mainly in Europe, North America, and Asia, have created the need for methodologies to plan the DC interconnections between countries. However, the planning process should not be developed in a local context but rather, in the long run, thus enabling the inclusion of regional electrical systems. This paper presents two main methodologies. The first one aims to design local Multi-Terminal DC grids (MTDC) at the national level, using the graph theory. The second methodology presented is the integration of local MTDC grids that can later be extended to regional, continental, or subcontinental grids. The methodology is applied in the planning of regional electrical integration of the Pacific basin countries.

Planning of high voltage direct current (HVDC) grids requires inclusion of reliability assessment of alternatives under study. This paper proposes a methodology to evaluate the adequacy of voltage source converter/VSC-HVDC networks. The methodology analyses the performance of the system using N-1 and N-2 contingencies in order to detect weaknesses in the DC network and evaluates two types of remedial actions to keep the entire system under the acceptable operating limits. The remedial actions are applied when a violation of these limits on the DC system occurs; those include topology changes in the network and adjustments of power settings of VSC converter stations. The CIGRE B4 DC grid test system is used for evaluating the reliability/adequacy performance by means of the proposed methodology in this paper. The proposed remedial actions are effective for all contingencies; then, numerical results are as expected. This work is useful for planning and operation of grids based on VSC-HVDC technology.

Electrically isolated areas are separated by a great distance and, normally, have a considerably low demand; in consequence, these are non-interconnected from the main power grid or electrical national transmission systems. Great distance and low demand are the reasons why an interconnection project in high voltage AC is not feasible in most of these cases. Nevertheless, there are some isolated areas with high power demand and even though they are separated from the main grid by large distances and hard terrains; however, it is still reasonable to think about an interconnection project. This paper had developed a methodology that allows the evaluation of viability, technically and economically, of a HDVC-VSC interconnection project for great distance and high demand considering overhead and/or underground DC line. The methodology was applied to a case of study in Peru, based on the projected interconnection between Moyobamba and the isolated area of Iquitos; showing that HVDC is a feasible alternative.

The growth of utilisation of wind power plants (WPP) in power systems placed at long distance of the transmission power system has shown that the best connecting alternatives are by means of high-voltage direct current lines (HVDC) using voltage source converter (VSC) stations. Generally, the bus closest to the WPP and with the highest level of short circuit is selected as the best option to connect the VSC-HVDC link, mainly due to economic criteria. This paper proposes a methodology to select the best connection point in the AC system, taking advantage of the potential increase of transmission capability due to the reactive power controlled at the VSC converter stations; measured as the increment of the loadability margin computed by means of PV curves. Nevertheless, a trade-off between this benefit and the cost of overhead HVDC transmission line as consequence of the length differences among alternatives is required. This trade-off is computed as the cost of the equivalent STATCOM required to get the same loadability margin. Thus, a technical-economical comparison of connection alternatives allows the selection of the best option for connecting the VSC-HVDC line. The methodology has been applied to connect a WPP of 500 MW to the NETS.

The interconnection of remote large power systems, and the connection of large non-synchronous renewable power sources to AC power systems have found solutions by means of transmission in high voltage direct current (HVDC) using technology based on voltage source converters (VSC). This technology has the advantage of fast response the possibility of providing reactive power to AC systems, and the use of supplementary control signals to their automatic voltage regulators to improve stability AC systems. This paper proposes the computation of robust supplementary controller type H ∞ based on low-order models of the power system, obtained by application of N4Sid identification technique, to be installed at the VSC converter stations of a HVDC link to dampen electromechanical weak modes. The proposed model shows that using simulated input/output data by means of typical software available at utilities is possible and useful. The methodology includes the modeling of uncertainties due to the different operational points where the power system can be placed by load variations and generation dispatch. This paper also presents a methodology for the computation of robust supplementary control at VSC-HVDC stations that guarantee robustness in a wide range of operating conditions and even better to improve the damping of electromechanical oscillations. It is also proposed a methodology for defining the weighted functions based on the uncertainties theory. Likewise, it is validated with the simulation of a critical contingency in a weakly damped system obtaining an improvement in damping of electromechanical oscillations. The robust supplementary control is compared to the performance of the classical POD.

Water has a rich phase diagram with several crystals, as confirmed by experiments. High-pressure and high-temperature water is of interest for Earth’s mantle and exoplanetary investigations. It is in this region of the phase diagram of water that new plastic crystal phases of water have been revealed via computer simulations by both classical forcefields and ab initio calculations. However, these plastic phases still remain elusive in experiments. Here, we present a complete characterization of the structure, dynamics, and thermodynamics of the computational plastic crystal phases of water using molecular dynamics and the two-phase thermodynamic method and uncover the interplay between them. The relaxation times of different reorientational correlation functions are obtained for the hypothetical body-centered-cubic and face-centered-cubic plastic crystal phases of water at T = 440 K and P = 8 GPa. Results are compared to a high pressure liquid and ice VII phases to improve the understanding of the plastic crystal phases. Entropy results indicate that the fcc crystal is more stable compared to the bcc structure under the studied conditions.

The use of renewable non-conventional energy sources, as wind electric power energy and photovoltaic solar energy, has introduced uncertainties in the performance of bulk power systems. The power system availability has been employed as a useful tool for planning power systems; however, traditional methodologies model generation units as a component with two states: in service or out of service. Nevertheless, this model is not useful to model wind power plants for availability assessment of the power system. This paper used a statistical representation to model the uncertainty of power injection of wind power plants based on the central moments: mean value, variance, skewness and kurtosis. In addition, this paper proposed an availability assessment methodology based on application of this statistical model, and based on the 2m+1 point estimate method the availability assessment is performed. The methodology was tested on the IEEE-RTS assuming the connection of two wind power plants and different correlation among the behavior of these plants.

Time-delay is inherent to communications schemes in power systems, and in a closed loop strategy the presence of latencies increases inter-area oscillations and security problems in tie-lines. Recently, Wide Area Measurement Systems (WAMS) have been introduced to improve observability and overcome slow-rate communications from traditional Supervisory Control and Data Acquisition (SCADA). However, there is a need for tackling time-delays in control strategies based in WAMS. For this purpose, this paper proposes an Enhanced Time Delay Compensator (ETDC) approach which manages varying time delays introducing the perspective of network latency instead dead time, also, ETDC takes advantage of real signals and measurements transmission procedure in WAMS building a closed-loop memory control for power systems. The strength of the proposal was tested satisfactorily in a widely studied benchmark model in which inter-area oscillations were excited properly.

El presente libro lleva como título “Risaralda competitiva, generando alianzas en investigación para el desarrollo”, resultado del V encuentro de investigadores del departamento de Risaralda realizado en el mes de noviembre del año 2020. Evento en el cual se presentaron las últimas investigaciones realizadas en las diferentes instituciones educativas del departamento; quienes hacen parte de la Mesa de Investigaciones de Risaralda; ejercicio de gran interés que arroja resultados de investigaciones en diferentes áreas como son las Ciencias Agrícolas, Ciencias sociales, Ciencias de la salud, Ciencias de la tecnología y la información.

HVDC links has been proposed due to the lack of feasibility, of traditional AC transmission systems, to transport great amounts of power in systems with large physical connections. SuperGrids are one of the applications of these HVDC connections, where it must consider, not only the AC-DC conversions, but the DC power flow of the multiple nodes connected with the DC voltage. SuperGrids also have the purpose of interconnecting different countries with some independent sources and loads found in remotes places. Thus, the grid may enable an electrical market that must be moderated by an independent operator. This operator must guarantee the maximization of the global benefit of all parts, and this constitutes an economic dispatch problem. Thus, this paper proposes a methodology of assignation the optimal parameters of generators and converters that minimizes the total production cost of electrical energy. This approach solves the economic dispatch problem in a HVDC Grid taking into account the security restrictions of both AC-DC systems. The methodology is validated using the DC grid test-system benchmark provided by CIGRE. The algorithm was tested in not only different cost scenarios, but also different constraints conditions.

This paper proposes a methodology to develop a probabilistic model that determines the power output of a wind power park as a probability discrete distribution function, taking into account wind speed, wind direction, state of operation of wind turbines and grid components of wind parks. Probabilistic Monte Carlo simulation is used to develop the modeling. Then, this discrete model is used to develop a reliability assessment of the bulk power system applying the theorem of total probability. The proposed model is tested on the IEEE Reliability Test System of 24 nodes.

This paper proposes a methodology to measure the impact on power systems caused by the massive installation of Wind Power Plants (WPP) based on the computation of the system loadability by analyzing the PV curves in different scenarios of participation of WPP, considering the probabilistic behavior of the wind through the point estimate method (PEM). This methodology is implemented in the IEEE 39 Bus New England test system by comparing the probabilistic loadability margin between an initial case without WPP and several cases with different percentages of WPP participation, between 9% and 33% of total system generation capacity.

This paper proposes a method to find the optimal control scheme in the AC / DC converters considering the criteria of adjustment of voltage set points and the k-droop coefficient of each converter, with the objective of reduction losses in a HVDC grid. The differential evolution method is used for this optimization. To do this the control strategies and their characteristics is explained for each option of control system. The selection of the voltage control station (slack) is described together with the algorithm of selection of optimal voltage control scheme and the algorithm of optimization of voltage set points. Also, the CIGRE B4 DC grid test system benchmark is tested in steady and dynamic simulation to determine the advantages of the selected optimal control scheme and verify that the system maintains the stability when a fault has occurred.

The development of electrical interconnections over the Andean Community Nations (CAN) have been one of the energies, economic and social development proposals that could not be concluded in reason of different constraints most of them technical and economic. The most important technical constraints are the deficient reactive power supply between AC transmission grids, the synchronism, distances between possible substations, maximum power transfer and the lines over natural reserves. The maturity of HVDC technology will work over the different AC and HVAC constraints. The purpose of this paper is to develop an alternative of VSC-HVDC interconnections between the CAN countries developing the SINEA project in reduced national transmission grid.

Polarity control in semiconducting single-walled carbon-nanotube field-effect transistors (s-SWNT FETs) is important to promote their application in logic devices. The methods to turn the intrinsically ambipolar s-SWNT FETs into unipolar devices that have been proposed until now require extra fabrication steps that make preparation longer and more complex. It is demonstrated that by starting from a highly purified ink of semiconducting single-walled carbon nanotubes sorted by a conjugated polymer, and mixing them with additives, it is possible to achieve unipolar charge transport. The three additives used are benzyl viologen (BV), 4-(2,3-dihydro-1,3-dimethyl-1H-benzimidazol-2-yl)-N,N-dimethylbenzenamine (N-DMBI), which give rise to n-type field-effect transistors, and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F-4-TCNQ) which gives rise to p-type transistors. BV and N-DMBI transform the s-SWNTs transistors from ambipolar with mobility of the order of 0.7 cm(2) V-1 s(-1) to n-type with mobility up to 5 cm(2) V-1 s(-1). F-4-TCNQ transform the ambipolar transistors in p-type with mobility up to 16 cm(2) V-1 s(-1).

This paper aims to present an alternative with respect to the current plan of two point-to-point HVDC lines of connection between Colombia and Panama and Guajira-Cerromatoso, using a VSC MTDC link between the substations Colectora 2 and Cerromatoso in Colombia and Panama II in Panama. This paper presents a methodology used for the selection of the optimal voltage level of the MTDC grid, based on cost analysis of the construction and operation of the transmission lines required. Additionally, a sensitivity analysis will be performed related to the power capacity of each link, this with the objective of establishing a reference for future projects of similar characteristics, facilitating the selection of the optimal voltage level.

Cell-based biosensors constitute a fundamental tool in biotechnology, and their relevance has greatly increased in recent years as a result of a surging demand for reduced animal testing and for high-throughput and cost-effective in vitro screening platforms dedicated to environmental and biomedical diagnostics, drug development, and toxicology. In this context, electrochemical/electronic cell-based biosensors represent a promising class of devices that enable long-term and real-time monitoring of cell physiology in a noninvasive and label-free fashion, with a remarkable potential for process automation and parallelization. Common limitations of this class of devices at large include the need for substrate surface modification strategies to ensure cell adhesion and immobilization, limited compatibility with complementary optical cell-probing techniques, and the need for frequency-dependent measurements, which rely on elaborated equivalent electrical circuit models for data analysis and interpretation. We hereby demonstrate the monitoring of cell adhesion and detachment through the time-dependent variations in the quasi-static characteristic current curves of a highly stable electrolyte-gated transistor, based on an optically transparent network of printable polymer-wrapped semiconducting carbon-nanotubes.

Automatic voltage regulators and power system stabilizers have been employed successfully to deal with fast dynamics associated to local oscillations phenomena. Whereas, inter-area oscillations damping in large power systems requires remote feedback controllers fed by Wide Area Monitoring Systems (WAMS). Although these improvements in the inter-area oscillations behavior have been effective, a new challenge emerges: reaching stability with a closed loop control despite latencies due to measurements taken far away from the control centre. The research was motivated by the need for modernization of power systems capable of dealing with control difficulties in centralised WAMS for damping inter-area oscillations in power systems caused by delays in the communication system. Herein, time delay and control problems are addressed separately. The time delay problem is solved by a database based time compensation solution relying on the most updated available state of the system. The control problem is solved by a Model Predictive Control (MPC) with terminal cost and constraint set to handle complexities due to nonlinearities of the power system, the large scale of the problem and the parametric variations. Both solutions work in a coordinated way with local controllers to implement a decentralised coordinated strategy that manages slow global dynamics and fast local dynamics as well. The integrated proposed approach is called Time-Delay-Tolerant Model Predictive Control (TDT-MPC). Coordinated and coherent performance of the two TDT-MPC components (Kalman compensator and MPC) is achieved thanks to unifying power system reference models for both strategies. The approach has been tested on the IEEE 39 system and validated with time domain nonlinear simulations, obtaining post-fault damped oscillations and a good tracking of new power references when tripping tie lines.

The electronic structure of semiconducting carbon nanotubes selected through polymer functionalization is routinely verified by measuring the spectral van Hove singularity signature under ultraclean vacuum conditions. Interpreting the effect of unperturbed polymer adsorption on the nanotube energetic bands in solvent media is experimentally challenging owing to solvent molecular crowding around the hybrid complex. Here, a liquid-based scanning tunneling microscope and spectroscope operating in a noise free laboratory is used to resolve the polymer-semiconducting carbon-nanotube-underlying graphene heterostructure in the presence of encompassing solvent molecules. The spectroscopic measurements highlight the role of polymer packing and graphene landscape on the electronic shifts induced in the nanotube energy bands. Together with molecular dynamics simulations, our experimental findings emphasize the necessity of recording physicochemical and electronic properties of liquid phase solubilized hybrid materials in their native state.

We employ photoluminescence and pumpprobe spectroscopy on films of semiconducting single-walled carbon nanotubes (CNTs) of different chirality wrapped with either a wide band gap polyfluorene derivative (PF12) or a polythiophene with narrower gap (P3DDT) to elucidate the excited states interplay between the two materials. Excitation above the polymer band gap gives way to an ultrafast electron transfer from both polymers toward the CNTs. By monitoring the hole polaron on the polymer via its mid infrared signature, we show that also illumination below the polymer band gap leads to the formation of this fingerprint and infer that holes are also transferred toward the polymer. As this contradicts the standard way of discussing the involved energy levels, we propose that polymer-wrapped CNTs should be considered as a single hybrid system, exhibiting states shared between the two components. This proposition is validated through quantum chemical calculations that show hybridization of the first excited states, especially for the thiopheneCNT sample.

With the insertion of non-synchronous energies such as, solar and wind energy, the power systems face new challenges to maintain reliability and security in the electric service. For this purpose, this paper proposes an adaptive supplementary controller based on a reference model for the improvement of damping of weak electromechanical modes. Additionally, the supplementary controller uses fuzzy logic as an adjustment mechanism for tuning the proportional gain in the time. The methodology is applied into a test system with a total installed wind generation of 900 MW and an external HVDC connection with 600MW. The performance of the proposed control is compared to classic control with Power Oscillation Damping.

Voltage source converters (VSC) based HVDC grids are a secure alternative for power transmission in the electric regional integration of many countries around the world, and the integration of renewable sources. The main objective of this paper is to compare the dynamic performance of three modes of control of VSC stations the voltage control methods “Control margin voltage” and “Droop control voltage” to show that the droop voltage control strategy has better results than the voltage margin control strategy. The performance of these controllers is evaluated by means of a perturbation on a VSC station that consists of outage of the negative pole over the bipolar converter station in the DC subsystem DSC3 of the CIGRE DC Grid benchmark test system. The dynamic simulation allows conclude that using a strategic voltage control like margin control voltage is possible have a better level of voltage and active power in the lines DC, the establishment time of the system is 6s. The droop control voltage with acceptable levels of voltage and active power can be faster, stabilizing the system at 1s.

Semiconducting single‐walled carbon nanotubes (s‐SWNTs) are used as a protective interlayer between the lead sulfide colloidal quantum dot (PbS CQD) active layer and the anode of the solar cells (SCs). The introduction of the carbon nanotubes leads to increased device stability, with 85% of the initial performance retained after 100 h exposure to simulated solar light in ambient condition. This is in sharp contrast with the behavior of the device without s‐SWNTs, for which the photoconversion efficiency, the open circuit voltage, the short‐circuit current, and the fill factor all experiencing a sharp decrease. Therefore, the inclusion of s‐SWNT as interlayer in CQD SCs, give rise to SCs of identical efficiency (above 8.5%) and prevents their performance degradation. ISSN:2196-7350

With the growth of air transport, the air traffic control needs to enforce the Communication navigation surveillance air traffic management (CNS-ATM) because this is the back bone of the air operation in any country. This system has the responsibility of guaranteeing air safety and management of the national air space (NAS) that nowadays needs to increase the flight density to respond to the demand. To accomplish this, new technologies like air dependent surveillance broadcast (ADS-B) have been used to increase the accuracy and time response of data air surveillance sensor integration of sensor location and the reliability of ATM system. CNS-ATM system for surveillance and control of aircrafts have been mainly used in primary and secondary radars to calculate the aircraft position through signal delay or time difference between transponder pulses. The accuracy of each sensor depends on internal and external factors such as frequency, power, target distance, noise, maintenance, and others. When an aerodyne is detected by multiple sensors, it could create a multiple track in a geographic and temporal space where the aircraft will be possibly flying. This space depends of radar update time, aerodyne speed, and the accuracy of each sensor, and it is difficult to know where the aircraft really is. This work proposes a technique based on ADS-B for making an error calculation of each sensor in a fusion system, using business intelligence techniques for understanding the error condition of each sensor in a geographical area. Based on results, we propose a technique that could make an error correction to avoid phase shifts between sensors. The information of this data study was used for statistical calculation values such as variance and standard deviation. For fusion accuracy improvement, three steps have been proposed in this research. First, the use of the radar error by region and statistical values by calculating the Kalman filters for each sensor to reduce the internal error of the radar. Second, the bias measured against ADS-B signal, used like a parameter to calculate radar bias correction that could be applied as a feedback input in a homogenization signal process or tracking process to reduce sensor bias in a recurrent process. Third, the use of Kalman prediction characteristic to replace missing points in a trajectory calculation. This technique was implemented by Colombian system to reduce error and bias sensor and a user's quality perception in a radar tracking and fusion track system in a surveillance network. In this process, it was found that it is possible to use it by a repetitive error measured ADS-B track like a reference track to calculate the error and in this way, it could be possible to reduce the uncertainty about the aircraft position. On the other hand, the use of data analysis process based on business intelligent tools allows us to easier understand the radar error behavior. Both methodology and results will be described here.

Transmission expansion planning in AC power systems is well known and employs a variety of optimization techniques and methodologies that have been used in recent years. By contrast, the planning of HVDC systems is a new matter for the interconnection of large power systems, and the interconnection of renewable sources in power systems. Although the HVDC systems has evolved, the first implementations were made considering only the needs of transmission of large quantities of power to be connected to the bulk AC power system. However, for the future development of HVDC systems, meshed or not, each AC system must be flexible to allow the expansion of these for future conditions. Hence, a first step for planning HVDC grids is the planning and development of multi-terminal direct current (MTDC) systems which will be later transformed in a meshed system. This paper presented a methodology that use graph theory for planning MTDC grids and for the selection of connection buses of the MTDC to an existing HVAC transmission system. The proposed methodology was applied to the Colombian case, where the obtained results permit to migrate the system from a single HVDC line to a MTDC grid.

Printed random networks of polymer-wrapped multi-chiral semiconducting carbon nanotubes (s-SWCNTs) are an opportunity for mass-manufacturable, high-performance large-area electronics. To meet this goal, a deeper understanding of charge-transport mechanisms in such mixed networks is crucial. Here, charge transport in field-effect transistors based on inkjet-printed s-SWCNTs networks is investigated, obtaining direct evidence for the phases probed by charge in the accumulated channel, which is critical information to rationalize the different transport properties obtained for different printing conditions. In particular, when the fraction of nanotubes with smaller bandgaps is efficiently interconnected, the sparse network provides efficient charge percolation for band-like transport, with a charge mobility as high as 20.2 cm(2) V-1 s(-1). However, when the charges are forced by a less efficient morphology, to populate also higher bandgap nanotubes and and/or the wrapping polymer, thermally activated transport takes place and mobility drops. As a result, a trade-off between network density and charge transport properties is identified for device current optimization, in both p- and n-type regimes. These findings shed light on the fundamental aspects related to charge transport in printed s-SWCNT mixed networks and contribute to devise appropriate strategies for the formulation of inks and processes towards cost-effective mass production schemes of high-performance large-area electronics.

This paper presents a methodology to determine the adequate percentage of reactive power compensation required to provide an appropriate voltage support and mitigate the impact caused by the massive installation of Wind Power Plants (WPP) in a power system. Mainly, the impact in the system's loadability and the improvement achieved by installing several STATCOM to provide reactive compensation are measured through a probabilistic loadability margin that considers the intermittent behavior of the wind. In addition, the point estimate method is applied to give a stochastic characteristic to the analysis and to determine the statistical mean and standard deviation that are key values to identify the impact of WPP and the necessary reactive supply. This methodology is implemented in the IEEE New England test system (39 Bus) by comparing the statistical mean of loadability margin between an initial case and multiple cases considering different participation percentages of WPP (between 9% to 33%) and different percentages of reactive power compensation injected (between 15% to 75%) under normal operation conditions and considering N-1 contingency scenarios.

This paper proposes a methodology of integrated generation-transmission planning of power systems, that considers the penetration of renewable generation sources to be shared by two AC independent systems. Additionally, the methodology also deals with the interconnection of independent AC systems by means of HVDC grids. The methodology makes use of differential evolution optimization algorithms to search the optimal solution of the configuration of the HVDC grid. The methodology is tested on a proposed test system that interconnects IEEE-RTS system and the IEEE 39 bus system and two large generation sources, one a wind farm and the other one large hydroelectric source.

Planning of Flexible AC Transmission systems (FACTS) and other reactive power sources has traditionally been done considering steady state conditions. The strength of FACTS is mainly seen when considering the dynamic behavior after the occurrence of any disturbance like when a fault occurs, because they can stabilize the system voltage and control power flow. At the same time, transient voltage dips and slow voltage recovery issues are most effectively addressed by fast responding dynamic VAR sources. So, this paper proposes a probabilistic contingency severity index based on the probability of occurrence of the faults and the dynamic impacts on the network measured in trajectory voltage deviations that can be included as a dynamic constraint for reactive power planning. In this way, the objective of dynamic reactive power planning is to determine where and with what capacity shunt-FACTS should be located to obtain a voltage profile within acceptable limits. The proposed probabilistic contingency severity index shows its effectiveness as dynamic criteria for optimization of location and sizing of shunt-FACTS devices by testing on the IEEE 9 nodes system and on the IEEE 39 nodes system.

This paper proposes a methodology for the long-term integration of Latin American electrical power systems through a SuperGrid, using VSC-HVDC technology. The methodology proposes an optimization of the investment cost of the HVDC grid in order to size the necessary transport capacity of the HVDC grid. The optimization is carried out in two stages, the first one applies differential evolution methods for the optimization of the HVDC network for given generation scenarios defined according to weather conditions. The second stage consists of the application of the Pareto optimum evaluating the performance of each one of the suboptimal solutions obtained in the previous stage in the different weather scenarios, based on technical and economic indicators. The technical performance of the HVDC grid is evaluated, in both stages of the optimization process, by means of load flows of the DC Grid. Finally, the methodology proposed and the tools developed are used in the formulation of a first SuperGrid for Latin America.

The electric regional interconnection between countries is a major subject of the integrated generation and transmission planning. One of the purposes of this integration is to share large renewable generation sources between different bulk power systems. One alternative for the development of this integration is the development of HVDC-Grids based on the extension of the concept of multi-terminal DC converter stations to HVDC networks. This paper compares the regional integration between systems using HVDC-Grid or using conventional large HVAC systems. In both cases, an optimization planning processes is done. The methodology makes use of differential evolution optimization algorithms to search the optimal solution of the configuration of the HVDC-Grid or the large HVAC interconnection system. The benefits of a HVDC-Grid are shown on a test system that interconnects IEEE-RTS system and the IEEE 39 bus system in order to share two large generation sources.

This paper presents a three-phase loss allocation procedure for distribution networks. The key contribution of the paper is the computation of specific marginal loss coefficients (MLCs) per bus and per phase expressly considering non-linear load models for Electric Vehicles (EV). The method was applied in a unbalanced 12.47 kV feeder with 12,780 households and 1000 EVs under peak and off-peak load conditions. Results obtained were also compared with the traditional roll-in embedded allocation procedure (pro rata) using non-linear and standard constant power models. Results show the influence of the non-linear load model in the energy losses allocated. This result highlights the importance of considering an appropriate EV load model to appraise the overall losses encouraging the use and further development of the methodology

The transmission expansion planning using highvoltage direct current (HVDC) projects requires representative data for reliability assessment based on international projects currently in operation. For that reason, this paper presents a comprehensive review of HVDC projects and contributes to the estimation of reliability parameters for both kind of HVDC technologies, namely: line-commutated converter (LCC-HVDC) and voltage source converter (VSC-HVDC). For each technology, the results of the reliability parameters of each of the main components forming the HVDC system, either LCC or VSC, are presented. In addition, these results are used for the calculation of the reliability of a bipolar HVDC system, showing its application and comparing the two technologies.

Noncovalent functionalization of single-walled carbon nanotubes (SWNTs) using π-conjugated polymers has become one of the most effective techniques to select semiconducting SWNTs (s-SWNTs). Several conjugated polymers are used, but their ability to sort metallic and semiconducting species, as well as the dispersions yields, varies as a function of their chemical structure. Here, three polymers are compared, namely, poly[2,6-(4,4-bis-(2-dodecyl)-4H-cyclopenta[2,1-b;3,4b′]dithiophene)-alt-4,7(2,1,3-ben-zothiadiazole)] (P12CPDTBT), poly(9,9-di-n-dodecylfluorenyl-2,7-diyl) (PF12), and poly(3-dodecylthiophene-2,5-diyl) (P3DDT) in their ability to select two types of carbon nanotubes comprising small (≈1 nm) and large (≈1.5 nm) diameters. P12CPDTBT is a better dispersant than PF12 for small diameter nanotubes, while both polymers are good dispersants of large diameter nanotubes. However, these dispersions contain metallic species. P3DDT, instead presents the best overall performance regarding the selectivity toward semiconducting species, with a dispersion yield for s-SWNTs of 15% for small and 21% for large diameter nanotubes. These results are rationalized in terms of electronic and chemical structure showing that: (i) the binding energy is stronger when more alkyl lateral chains adsorb on the nanotube surface; (ii) the binding energy is stronger when the polymer backbone is more flex-ible; (iii) the purity of the dispersions seems to depend on a strong polymer– nanotube interaction.