There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Lanthanide-based luminescent hybrid materials.

This paper reviews the power electronic applications for wind energy systems. Various wind turbine systems with different generators and power electronic converters are described, and different technical features are compared. The electrical topologies of wind farms with different wind turbines are summarized and the possible uses of power electronic converters with wind farms are shown. Finally, the possible methods of using the power electronic technology for improving wind turbine performance in power systems to meet the main grid connection requirements are discussed.

A Review of the State of the Art of Power Electronics for Wind Turbines

This paper provides a thorough review of state-of-the-art current sensing techniques. It catalogues the current sensors according to the underlying physical principle in order to point out their strengths and weaknesses.

Current Sensing Techniques: A Review

The Kalman filter (KF) has received a huge interest from the industrial electronics community and has played a key role in many engineering fields since the 1970s, ranging, without being exhaustive, trajectory estimation, state and parameter estimation for control or diagnosis, data merging, signal processing, and so on. This paper provides a brief overview of the industrial applications and implementation issues of the KF in six topics of the industrial electronics community, highlighting some relevant reference papers and giving future research trends.

/pdf/industrial-applications-of-the-kalman-filter-a-review-tqdmwc4feq.pdf

Industrial Applications of the Kalman Filter: A Review

This paper analyzes the minimum energy capacity ratings that an energy-storage (ES) system should accomplish in order to achieve a defined constant power production in a photovoltaic (PV) power plant. ES is a key issue for the further integration of intermittent and stochastic renewable energy sources, which are not currently dispatchable due to their dependence on real-time weather conditions, as is the case of PV technology. This paper proposes and describes an energy management strategy (EMS) for operating PV power plants with ES in the future. The goal of this EMS is to endow these power plants with a constant production that can be controlled and hence traded on electricity markets. This paper presents simulated results on the percentage of time throughout the year during which a large-scale PV+ES plant operates properly with different ES ratings and according to different configurations of this EMS. Finally, a test bench was developed, and experimental results validating this EMS were obtained.

Evaluation of Storage Energy Requirements for Constant Production in PV Power Plants

This work presents a model predictive control (MPC) approach to manage in real-time the energy generated by a grid-tied photovoltaic (PV) power plant with energy storage (ES), optimizing its economic revenue. This MPC approach stands out because, when a long enough prediction horizon is used, the saturation of the ES system (ESS) can be advanced by means of a prediction model of the PV panels production. Therefore, the PV+ES power plant can modify its production so as to manage the power deviations with regard to that committed in the daily and intraday electricity markets, with the objective of reducing economic penalties. The initial power commitment is supposed in this work to be given by a higher level energy management operator. By a proper definition of its objective function, the predictive control allows us to economically optimize the PV+ES power plant performance. This control strategy is tested in simulations with actual data measured for different days with varying meteorological conditions. Results provide a good reference on the economic benefits which can be obtained thanks to the MPC introduction.

/pdf/predictive-power-control-for-pv-plants-with-energy-storage-571udwpup4.pdf

Predictive Power Control for PV Plants With Energy Storage

This paper proposes an optimized energy management strategy (EMS) for photovoltaic (PV) power plants with energy storage (ES) based on the estimation of the daily solar energy production. This EMS produces a constant-by-hours power reference which mitigates the stochastic nature of PV production typically associated to the solar resource, and enables PV power plants to take part in the day and intraday electricity markets. The possibility of using the intraday market sessions to refine the plant's power reference paves the way to minimizing the energy capacity ratings of the ES system required to operate the PV power plant without incurring excessive production deviations. This proposal is analyzed on an annual basis using actual irradiance data and theoretical irradiance models extracted from official databases.

/pdf/daily-solar-energy-estimation-for-minimizing-energy-storage-5aswi8cssa.pdf

Daily Solar Energy Estimation for Minimizing Energy Storage Requirements in PV Power Plants

This paper analyzes the behavior of a modular multilevel converter-high-voltage direct-current (MMC-HVDC)-connected offshore wind power plant (WPP) during dc faults. For that purpose, detailed models of the dc cable, MMC stations, and transformers have been used in order to obtain reliable results. The influence of the WPP control method in the short-circuit behavior of the HVDC link has also been studied. Results show that the dynamics of the WPP contribution to pole-to-ground faults are slightly slower than those of the wind turbines current control loops. Therefore, the wind turbine front-end converters can be used to reduce the peak and average value of the fault current in such a system. Moreover, it has been found that ferroresonant oscillations can appear in the offshore ac grid when the WPP delivers constant power during faults.

/pdf/analysis-of-the-performance-of-mmc-under-fault-conditions-in-2x2osnm6ig.pdf

Analysis of the Performance of MMC Under Fault Conditions in HVDC-Based Offshore Wind Farms

This paper is intended to fill a gap in the current literature comparing and contrasting the experience of a number of European countries, U.S. states, and Australia with regard to wind energy support policy and electricity market design. As wind penetrations increase, the nature of these arrangements becomes an increasingly important determinant of how effectively and efficiently this generation is integrated into the electricity industry. The jurisdictions considered in this paper exhibit a range of wind support policy measures from feed-in tariffs to green certificates, and electricity industry arrangements including vertically integrated utilities, bilateral trading with net pools, as well as gross wholesale pool markets. We consider the challenges that various countries and states have faced as wind generation expanded and how they have responded. Findings include the limitations of traditional feed-in tariffs at higher wind penetrations because they shield wind project developers and operators from the implications of their generation on wider electricity market operation. With regard to market design, wind forecasting and predispatch requirements are particularly important for forward markets, whereas the formal involvement of wind in scheduling and ancillary services (balancing and contingencies) is key for real-time markets.

http://bibing.us.es/proyectos/abreproy/70370/fichero/14.+Wind-+Comparison+of+Wind+Energy+Support+Policy+and+Electricity+Market+Design+in+Europe%2C+the+United+States%2C+and+Austra%7E1.pdf

Héctor Beltrán

Papers

Evaluation of Storage Energy Requirements for Constant Production in PV Power Plants

Predictive Power Control for PV Plants With Energy Storage

Daily Solar Energy Estimation for Minimizing Energy Storage Requirements in PV Power Plants

Analysis of the Performance of MMC Under Fault Conditions in HVDC-Based Offshore Wind Farms

Comparison of Wind Energy Support Policy and Electricity Market Design in Europe, the United States, and Australia