In this study, a technical and economic comparative analysis for evaluating the performance of various electrical photovoltaic (PV) plant configurations is presented. This methodology assessment is based on a holistic approach that calculates the levelised cost of energy (LCOE) considering the capital and installation cost of the PV components, as well as, the operation and maintenance costs over the lifetime of the project. Also, the potential economic impact of the installation of batteries for providing flat-output response is investigated. Moreover, a sensitivity analysis is included for considering both economic and technical uncertainty on the LCOE. The presented methodology compares the performance of six different configurations in three hypothetical PV power plants (1, 50 and 200 MW) located in Golden, Colorado, USA. The results obtained demonstrate that although some PV power plant configurations present better efficiency (higher performance ratio), they are not the most cost-effective solutions because of the requirement of extra equipment or the inclusion of expensive technologies. Finally, the benefit of including batteries into the system is shown for flat output operation. The results show that in spite of their inclusion increases the LCOE, extra revenues can be obtained when providing such services.
This book discusses HVDC grids based on multi-terminal voltage-source converters (VSC), which is suitable for the connection of offshore wind farms and a possible solution for a continent wide overlay grid. HVDC Grids: For Offshore and Supergrid of the Future begins by introducing and analyzing the motivations and energy policy drives for developing offshore grids and the European Supergrid. HVDC transmission technology and offshore equipment are described in the second part of the book. The third part of the book discusses how HVDC grids can be developed and integrated in the existing power system. The fourth part of the book focuses on HVDC grid integration, in studies, for different time domains of electric power systems. The book concludes by discussing developments of advanced control methods and control devices for enabling DC grids.
Presents the technology of the future offshore and HVDC grid
Explains how offshore and HVDC grids can be integrated in the existing power system
Provides the required models to analyse the different time domains of power system studies: from steady-state to electromagnetic transients
This book is intended for power system engineers and academics with an interest in HVDC or power systems, and policy makers. The book also provides a solid background for researchers working with VSC-HVDC technologies, power electronic devices, offshore wind farm integration, and DC grid protection.
This paper analyses, from a steady state point of view, the potential benefit of a Wind Power Plant (WPP) control strategy whose main objective is to maximise its total energy yield over its lifetime by taking into consideration that the wake effect within the WPP varies depending on the operation of each wind turbine. Unlike the conventional approach in which each wind turbine operation is optimised individually to maximise its own energy capture, the proposed control strategy aims to optimise the whole system by operating some wind turbines at sub-optimum points, so that the wake effect within the WPP is reduced and therefore the total power generation is maximised. The methodology used to assess the performance of both control approaches is presented and applied to two particular study cases. It contains a comprehensive wake model considering single, partial and multiple wake effects among turbines. The study also takes into account the Blade Element Momentum (BEM) theory to accurately compute both power and thrust coefficient of each wind turbine. The results suggest a good potential of the proposed concept, since an increase in the annual energy captured by the WPP from 1.86% up to 6.24% may be achieved (depending on the wind rose at the WPP location) by operating some specific wind turbines slightly away from their optimum point and reducing thus the wake effect. (C) 2015 Elsevier Ltd. All rights reserved.
de Prada, M.; Igualada , L.; Corchero, C.; Gomis-Bellmunt, O.; Sumper, A. IEEE transactions on power systems Vol. 30, num. 4, p. 1868-1876 DOI: 10.1109/TPWRS.2014.2354457 Data de publicació: 2015-07-01 Article en revista
The aim of this paper is to present a hybrid AC-DC offshore wind power plant (OWPP) topology and to optimize its design in order to minimize the OWPP's total cost. This hybrid concept is based on clustering wind turbines and connecting each group to an AC/DC power converter installed on a collector platform which is located between the AC wind turbine array and the HVDC offshore platform. Thereby, individual power converters of each wind turbine are not required, since such AC/DC converters can provide variable speed generator control for each cluster. The optimal design for an OWPP based on the hybrid AC-DC topology is formulated as a MINLP problem. The capital costs of each component within the OWPP as well as the costs associated to the inherent losses of this topology are minimized. The optimal number of AC/DC converters and offshore collector platforms needed, as well as their locations, are determined. The cable route connecting the wind turbines between each other is also optimized. The results suggests a good potential for the hybrid AC-DC OWPP topology achieving a total cost saving of 3.76% for the case study compared to the conventional OWPP topology.
The existence of HVDC (High Voltage Direct Current) transmission systems for remote offshore wind power plants allows devising novel wind plant concepts, which do not need to be synchronized with the main AC grid. This paper proposes an OWPP (offshore wind power plant) design based on variable speed wind turbines driven by DFIGs (doubly fed induction generators) with reduced power electronic converters connected to a single VSC-HVDC converter which operates at variable frequency and voltage within the collection grid. It is aimed to evaluate the influence of the power converter size and wind speed variability within the WPP on energy yield efficiency, as well as to develop a coordinated control between the VSC-HVDC converter and the individual back-to-back reduced power converters of each DFIG-based wind turbine in order to provide control capability for the wind power plant at a reduced cost. To maximise wind power generation by the OWPP, an optimum electrical frequency search algorithm for the VSC-HVDC converter is proposed. Both central wind power plant control level and local wind turbine control level are presented and the performance of the system is validated by means of simulations using MA'FLAB/Simulink (R). (C) 2015 Elsevier Ltd. All rights reserved.
Mancilla, F.; Dominguez, J.; de Prada, M.; Gomis-Bellmunt, O.; Singh, M.; Muljadi, E. Energy conversion and management Vol. 97, p. 315-322 DOI: 10.1016/j.enconman.2015.03.069 Data de publicació: 2015-06-01 Article en revista
The rapid increase of wind power penetration into power systems around the world has led transmission system operators to enforce stringent grid codes requiring novel functionalities from renewable energy-based power generation. For this reason, there exists a need to asses whether wind turbines (WTs) will comply with such functionalities to ensure power system stability. This paper demonstrates that Type-2 WTs may induce sub-synchronous resonance (SSR) events when connected to a series-compensated transmission line, and with proper control, they may also suppress such events. The paper presents a complete dynamic model tailored to study, via eigenanalysis, SSR events in the presence of Type-2 WTs, and a systematic procedure to design a power system stabilizer using only local and measurable signals. Results are validated through a case study based on the IEEE first benchmark model for SSR studies, as well as with transient computer simulations. (C) 2015 Elsevier Ltd. All rights reserved.
Offshore wind power plants (OWPPs) tend to be larger in size and distant from shore. It is widely accepted that for long distances HVDC links are preferred over HVAC transmission. Accordingly, one possible approach might be to consider not only a DC transmission system but also for the WPP collection grid. In this paper, a technical and economic comparison analysis of the conventional AC OWPP scheme and four proposed DC OWPPs topologies is addressed. Due to the conceptual novelty of DC technologies for OWPPs, uncertainty on electrical parameters and cost functions is relevant. A sensitivity analysis of the cost and efficiency of the components, OWPP rated power, export cable lengths and some economic data is carried out. For this study, a methodology is proposed and implemented in DIgSILENT Power Factory. To compare conventional AC offshore collector grid and the various proposed DC configurations, an OWPP based on Horn's Rev wind farm is selected as base case. The analysis of the results shows that, in general terms, DC OWPPs present capital costs comparable with conventional AC OWPPs, as well as lower energy losses, concluding that DC collector grid could be of interest for future OWPP installations. (C) 2015 Elsevier Ltd. All rights reserved.
The aim of this paper is to analyse, from the technical and economic point of view, the suitability of a proposed Offshore Wind Power Plant (OWPP) scheme based on removing the individual power converters of each wind turbine and connecting a turbine cluster (or an entire WPP) to a single large power converter (SLPC), by means of a centralised control. This proposed concept is specially worthwhile for HVDC interfaced offshore or remote WPPs where a common power converter (LCC or VSC) is required at the connection point of the wind farms. According to this approach, two WPP topologies are studied depending on whether the SLPC operates at variable or constant frequency (SLPC-VF or SLPC-CF). A detailed methodology to assess any WPP layout under any wind condition is presented and applied to a case study. In order to obtain accurate results, a wake model considering single, partial and multiple wakes within a WPP is considered. The implemented algorithm takes into account the steady-state and maintenance (preventive and corrective) energy losses, as well as investment and operation and maintenance (O&M) costs, to provide a precise technical and economic assessment of each WPP topology analysed. Due to the uncertainty of certain parameters, a sensitivity analysis varying the cost and efficiency of the individual power converters of each wind turbine, as well as the main economic indicators, has been performed. The results obtained suggests a good potential for the SLPC-VF scheme achieving a total cost saving of up to 6% compared to the conventional WPP topology, based on individual power converters connected to each turbine. Likewise, the effectiveness of implementing an optimum electrical frequency calculation algorithm for variable frequency operation within the WPP is demonstrated as a greater economic benefit can be realised for SLPC-VF instead of SLPC-CF scheme. (C) 2014 Elsevier Ltd. All rights reserved.
de Prada, M.; Mancilla, F.; Dominguez, J.; Muljadi, E.; Singh, M.; Gomis-Bellmunt, O.; Sumper, A. International journal of electrical power and energy systems Vol. 55, p. 714-722 DOI: 10.1016/j.ijepes.2013.10.025 Data de publicació: 2014-02 Article en revista
de Prada, M.; Dominguez, J.; Mancilla, F.; Muljadi, E.; Singh, M.; Gomis-Bellmunt, O.; Sumper, A. IEEE Green Technologies Conference p. 226-232 DOI: 10.1109/GreenTech.2013.42 Data de presentació: 2013-04 Presentació treball a congrés
Wind turbines (WTs) employing a wound rotor induction generator with adjustable external resistors are known as Type-2 WTs. This WT topology is available in USA since 2001. This WT is regulated by controlling its pitch angle and its external rotor resistor to operate as a variable slip WT. The slip range can reach up to 10% above synchronous speed. This paper demonstrates that with a proper control, Type-2 WTs are capable to damp out sub synchronous resonance (SSR) oscillations commonly found in series-compensated transmission lines. The size of wind power plant (WPP) has increased over the years and some WPP exceeds 500 MW. They can be treated as energy sources which can regulate the power delivered to the grid. In order to analyze the capability of Type-2 WPPs to damp power system oscillations, the IEEE first benchmark model for SSR studies is modified with an aggregated Type-2 WPP model connected to the system. An additional control loop is implemented to modulate the effective rotor resistance so that SSR oscillations can be damped. The models are implemented and simulated using PSCAD/EMTDC software platform.
In planning the installation and operation of wind turbines in the offshore environment, finding new
technological solutions is a key element for the economic success of offshore wind projects and
represents a completely new challenge compared to their onshore counterpart. The tendency is that wind turbines will continue growing larger and more powerful and will be installed further away and in deeper waters, leading to more complex infrastructures and greater challenges.
There’s a proven experience in the planning and front end engineering of fixed offshore wind farms.
Promoters and engineering companies have tools for the costs calculation and wind farm planning,
that support the decision making process for the investment. In deep offshore wind farms, there’s
still a lack of this type of tools due to the development stage of the technology: only two full scale prototypes installed. These tools can help in the optimization of the wind farm and costs reduction.
de Prada, M.; Sumper, A.; Gomis-Bellmunt, O. IEEE Symposium on Power Electronics and Machines for Wind and Water Applications p. 1-8 DOI: 10.1109/PEMWA.2012.6316406 Data de presentació: 2012-07 Presentació treball a congrés