• Energy Research

This paper proposes a method to evaluate the effect of Distributed Generation (DG) on a protection scheme coordination of a distribution network. The protection scheme includes configurations as fuse-fuse and recloser-fuse. DG integration, simulated in OpenDSS, includes 16 scenarios with different penetration and spread levels. Results, after faults, show reactions of protection devices, such as Unexecuted trip, Trip ahead and False tripping; causing a deviation from the expected protection coordination behaviour. Reliability index Energy Not Supplied is used to measure the impact of faults. In summary, scenarios with spread in all nodes present the best performance for medium penetration levels, although scenarios with generation only in 2 nodes are preferred for high penetration levels.

Capítulos en libros This paper presents a method for calculation of stationary Power Quality Disturbances-PQD based on measurements, distribution system modeling and Monte Carlo techniques. A method to simulate PQD with specific random behavior based on Perfect Sampling is proposed. Three non-sinusoidal conditions power quantities are employed to illustrate the proposed methodology, and a proposal for statistical interpretation of simulated results is presented as well. info:eu-repo/semantics/publishedVersion

This paper presents the measurement and characterization of current supraharmonic emission levels caused by commonly used electronic devices. A system setup was developed and signal processing techniques were proposed to identify lower and higher frequency phenomena, emission frequency bands and distortion indicators. Finally, a summary of emission levels is presented.

This paper is aimed to explore the relationship between the network topology and the network performance in terms of long-term voltage stability. For this purpose, performance indicators for taking into account both aspects are proposed. A six bus test system is proposed, two operational conditions are presented, and eight different grid topologies are investigated. The results show that long-term voltage stability depends on how generation and load are distributed throughout the system. The results reveal that a meshed configuration does not necessarily represent the most desirable configuration.

This paper presents a formulation of the optimal power flow (OPF) problem for transmission systems with the presence of wind generation. The OPF was modeled as a robust design optimization problem focused on ensuring that the probability that the power balance constraints are observed within a tolerance and that the boundaries of the design variables is respected. A simulation tool was developed implementing the model and it was tested with two power systems, two different wind probability distributions and two solution methods. Test results validated the proposed formulation giving optimal solutions that satisfy the power balance probabilistic constraint with the selected tolerance. The formulation is a simple model to calculate an optimal operation point for a power system with wind farms. This is an initial work in the formulation of an optimal operation model for large scale hybrid power system.

The increasing penetration of distributed generation (DG) could cause positive and adverse impacts on distribution power grids. The study of these effects could lead to methodological guidelines for sizing and location of renewable energy sources. In this paper several simulations of a distibution system of MV with different locations and penetration levels of DG are performed. Performance parameters as transmission capacity and voltage level are calculated and the impact of the different penetration scenarios is assessed. Finally a relationship among benefits, the Hosting Capacity (HC), and the distance between feeder-head and DG location is characterized. A new index is proposed to value the better location of units and generation power based on this relationship.

This paper presents the application of Demand Response (RD) to evaluate the flexibility of a customer group based on an aggregated stochastic demand model, whose behavior and decision making is based on recent statistical surveys. The sample of users is evaluated in two scenarios. First scenario applies a negative incentive on which 36% of the customers respond and overcome it. The second scenario uses a power peak tariff where customers voluntarily reduce the cost in their bill. About 5% of reduced peak demand is achieved with low effect on customer comfort.

Abstract Electric vehicles (EVs) will help to decarbonize energy systems. However, their connection to on-board level 2 chargers (7.2 kW) at household facilities brings challenges to Distribution Network Operators (DNOs) as they can affect the power quality of low voltage (LV) networks. In order to truly assess these effects, the electrical behavior of the on-board charger in terms of its non-linear content, power demand, and charge rate must be understood first. Nonetheless, most modeling methodologies with this aim result in circuital approaches, and thus, in heavy computational burdens, or assume simplified representations that do not correspond to the reality of the charge. To overcome this, we present a new methodology to model the power quality characteristics of EVs based on measured data from the harmonic spectra of the charger. The model provides a precise and efficient electrical characterization, where probabilistic models of the harmonic spectra are used to compute the power demand during every stage of the charge. Due to its probabilistic nature, these harmonic spectra are represented using Gaussian Mixture Models. We validate the model contrasting simulated data versus real measured one. Then, we illustrate a case study of the model in a LV network power quality assessment with different EV penetration levels, considering time-series harmonic power flows with 10-min resolution under a Monte Carlo approach. Obtained results revealed an increase in the network chargeability and voltage unbalance, along with an increased content of the third harmonic, which appears to be the most intense.

<p><span style="font-family: OptimaLTStd; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">Current and voltage harmonic levels in LV grids depend not only on the harmonic emission of non-linear loads, but also on the characteristics of the grid and the voltage distortion of the upstream grid. Based on several measurements, it was found that Colombia and<span style="font-family: OptimaLTStd; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> Germany have considerable differences in the current harmonic emission of electronic devices and voltage distortion in the LV-grids.<span style="font-family: OptimaLTStd; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> These differences are the result of different regulation methodologies and the characteristics of the grid. Detail measurement campaigns are needed in both countries in order to verify the voltage and current harmonic levels, and to analyze the network efficiency<span style="font-family: OptimaLTStd; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> and hosting capacity in terms of harmonics.</span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /><br class="Apple-interchange-newline" /></span></p>