Germán Morales-España

Germán Morales-España
TNO | tno · TNO Energy Transition

PhD, MSc

About

86
Publications
65,100
Reads
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1,837
Citations
Additional affiliations
October 2010 - present
Universidad Pontificia Comillas
October 2010 - October 2014
Kungliga Tekniska Högskolan (KTH)
Position
  • PhD (c)
September 2010 - September 2014
Universidad Pontificia Comillas
Position
  • PhD Student

Publications

Publications (86)
Article
Full-text available
Most of the power-to-heat and thermal energy storage technologies are mature and impact the European energy transition. However, detailed models of these technologies are usually very complex, making it challenging to implement them in large-scale energy models, where simplicity, e.g., linearity and appropriate accuracy, are desirable due to comput...
Article
Full-text available
The North Sea Offshore Grid concept has been envisioned as a promising alternative to: 1) ease the integration of offshore wind and onshore energy systems, and 2) increase the cross-border capacity between the North Sea region countries at low cost. In this paper we explore the techno-economic benefits of the North Sea Offshore Grid using two case...
Preprint
Full-text available
Energy storage models require binary variables to correctly model reserves and to ensure that the storage cannot charge and discharge simultaneously. This paper proposes a tight linear program (LP), i.e., convex hull, for the storage, which guarantees that there is no better LP approximation to its mixed-integer program (MIP) counterpart. Although...
Article
We propose a power-based unit commitment formulation with capacity and intra-hour ramp reserves for dealing with intra-hour wind power variability and uncertainty. Although the formulation has an hourly resolution, the intra-hour ramp requirements capture wind power ramp excursions with a time duration below one hour, and thus allows the formulatio...
Preprint
Full-text available
The North Sea Offshore Grid concept has been envisioned as a promising alternative to: 1) ease the integration of offshore wind and onshore energy systems, and 2) increase the cross-border capacity between the North Sea region countries at low cost. In this paper we explore the techno-economic benefits of the North Sea Offshore Grid using two case...
Article
Full-text available
Models with a wide technological representation of energy systems can hardly adopt hourly resolutions to study the energy transition towards low-carbon technologies due to extended problem size. This compromises the model's ability to address the challenges of variable renewable energy sources and the cost-effectiveness of cross-sectoral flexibilit...
Preprint
Full-text available
This paper presents power-based unit commitment (UC) formulations with N-1 security constraints. Two different formulations are proposed, one with constant reserves within the hour and one with time-varying reserves. The formulations are compared to a conventional energy-based UC formulation using different examples. We show that the energy-based f...
Article
Full-text available
The North Sea region, located in the Northwest of Europe, is expected to be a frontrunner in the European energy transition. This paper aims to analyse different optimal system configurations in order to meet net-zero emission targets in 2050. Overall, the paper presents two main contributions: first, we develop and introduce the IESA-NS model. The...
Article
The planning of future power systems with high shares of renewable generation requires modelling large and complex systems over long time periods, resulting in models which are computationally heavy to solve. For this reason methods that can be used to decrease the size of power system dispatch models are needed. A common method in large scale plan...
Article
Full-text available
Demand response (DR) is expected to play a major role in integrating large shares of variable renewable energy (VRE) sources in power systems. For example, DR can increase or decrease consumption depending on the VRE availability, and use generating and network assets more efficiently. Detailed DR models are usually very complex, hence, unsuitable...
Article
This paper presents a security constrained unit commitment (SCUC) with continuous intra-hour time-varying reserves. The hourly formulation extends the power-based UC formulation and has reserves which vary continuously within the hour, as opposed to the traditional hourly energy-based SCUC that uses constant reserves within the hour. We show that t...
Book
Full-text available
This report summarises findings on wind integration from the 17 countries or sponsors participating in the International Energy Agency Wind Technology Collaboration Programme (IEA Wind TCP) Task 25 from 2006–2020. Both real experience and studies are reported. Many wind integration studies incorporate solar energy, and most of the results discussed...
Preprint
Full-text available
We propose a power-based unit commitment (UC) formulation with capacity and intra-hour ramp reserves for dealing with intra-hour wind power variability and uncertainty. Although the formulation has an hourly resolution, the intra-hour ramp requirements capture wind power ramp excursions with a time duration below one hour, and thus allows the formu...
Preprint
Full-text available
Most of the power-to-heat and thermal energy storage technologies are mature and already impact the European energy transition. However, detailed models of these technologies are usually very complex, making it challenging to implement them in large-scale energy models, where simplicity, e.g., linearity and appropriate accuracy, are desirable due t...
Article
In this paper, we present an optimisation integrated energy system model (IESA-Opt) for the Netherlands with the use of a linear programming formulation. This state-of-the-art model represents a scientific contribution as it integrates a European power-system model with a complete sectoral representation of the energy system technologies and infras...
Article
Full-text available
Planning of future energy systems with higher prevalence of wind and solar energy requires a careful representation of the temporal and operational characteristics of the system in the investment planning model. This study aims to identify the aspects that should be considered when selecting the representation for a particular system. To demonstrat...
Article
Full-text available
The importance of spatial resolution for energy modelling has increased in the last years. Incorporating more spatial resolution in energy models presents wide benefits, but it is not straightforward, as it might compromise their computational performance. This paper aims to provide a comprehensive review of spatial resolution in energy models, inc...
Article
Full-text available
The future energy system is widely expected to show increasing levels of integration across differing energy carriers. Electricity, hydrogen, methane and heat systems may become increasingly interdependent due to coupling through conversion and hybrid energy technologies. Market parties, network operators, policy makers and regulators require tools...
Article
To lower CO2 emissions, policy makers want to integrate as much variable renewable energy (VRE) as possible into power systems. This has been translated into targets for VRE as a share of total electricity generation and policies that aim to maximize the use of electricity available from VRE sources. However, in this paper we demonstrate that it is...
Article
Full-text available
The power system is undergoing a significant change as it adapts to the intermittency and uncertainty from renewable generation. Flexibility from loads such as electric vehicles (EVs) can serve as reserves to sustain the supply-demand balance in the grid. Some reserve markets have rules for participation that are computationally challenging for agg...
Article
Full-text available
Improving energy system modeling capabilities can directly affect the quality of applied studies. However, some modeling trade-offs are necessary as the computational capacity and data availability are constrained. In this paper, we demonstrate modeling trade-offs resulting from the modification in the resolution of four modeling capabilities, name...
Article
Driven by climate change concerns, Europe has taken significant initiatives toward the decarbonization of its energy system. The European Commission (EC) has set targets for 2030 to achieve at least 40% reduction in greenhouse gas emissions with respect to the 1990 baseline level and cover at least 32% of the total energy consumption in the Europea...
Preprint
Full-text available
To lower CO2 emissions, policy makers want to integrate as much variable renewable energy (VRE) as possible into power systems. This has been translated into targets for VRE as a share of total electricity generation and policies that aim to maximize the use of electricity available from VRE sources. However, in this paper we demonstrate that it is...
Preprint
Full-text available
This paper presents a security constrained unit commitment (SCUC) with continuous intra-hour time-varying reserves. The hourly formulation extends the power-based UC formulation and has reserves which vary continuously within the hour, as opposed to the traditional hourly energy-based SCUC that uses constant reserves within the hour. We show that t...
Article
Full-text available
Flexibility requirements are becoming more relevant in power system planning due to the integration of variable Renewable Energy Sources (vRES). In order to consider these requirements Generation Expansion Planning (GEP) models have recently incorporated Unit Commitment (UC) constraints, using traditional energy-based formulations. However, recent...
Preprint
Full-text available
In energy systems with large penetrations of variable renewable energy, demand response is expected to play a major role due to its potential to provide flexibility to the system. For example, demand response can reduce peak generation capacity requirements, function as a reserve, use generating units more efficiently, and improve the utilization o...
Article
This paper proposes a Clustered Unit Commitment (CUC) formulation to accurately model flexibility requirements such as ramping, reserve, and startup/shutdown constraints. The classic CUC intrinsically and hiddenly overestimates the individual unit's flexibility, thus being unable to replicate the result of the individual UC. This paper present a se...
Article
Full-text available
The increase of solar photovoltaic penetration poses several challenges for distribution network operation, mainly because such high penetration might cause reliability problems like protection malfunctioning, accelerated decay of voltage regulators and voltage violations. Some control strategies avoid such drawbacks at the cost of not fully exploi...
Preprint
Full-text available
Flexibility requirements are becoming more relevant in power system planning due to the integration of variable Renewable Energy Sources (vRES). In order to consider these requirements Generation Expansion Planning (GEP) models have recently incorporated Unit Commitment (UC) constraints, using traditional energy-based formulations. However, recent...
Article
Full-text available
Existing electricity markets, based on energy, are inefficient. • We compare power-based scheduling to the current practice of increasing resolution. • Power-based scheduling results in less reserve activation at equal computation time. • Increasing the resolution requires great computational expense. • We provide a set of market rules to implement...
Preprint
Full-text available
This paper proposes a Clustered Unit Commitment (CUC) formulation to accurately model flexibility requirements such as ramping, reserve, and startup/shutdown constraints. The CUC is commonly applied in long-term planning models to approximate the units' operational flexibility in power systems due to its computational advantages. However, the class...
Preprint
Full-text available
This paper proposes a Clustered Unit Commitment (CUC) formulation to accurately model flexibility requirements such as ramping, reserve, and startup/shutdown constraints. The CUC is commonly applied in large and long-term planning models to approximate the units' operational flexibility in power systems due to its computational advantages. However,...
Article
Corrections were made to author information for the paper, “Energy management system with PV power forecast to optimally charge EVs at the workplace,” (van Der Meer, D., et al), IEEE Trans. Ind. Informat., vol. 14, no. 1, pp. 311–320, Jan. 2018.
Conference Paper
Full-text available
In power systems, demand and supply always have to be balanced. This is becoming more challenging due to the sustained penetration of renewable energy sources and their inherit uncertain production. Because of the increasing amount of electrical vehicles (EVs), and the high capacity and flexibility of their charging process, EVs are a good candidat...
Conference Paper
Full-text available
Approximations made in energy markets can result in suboptimal or even infeasible schedules for generating units and inaccurate predictions of actual costs and wind curtailment. Here we illustrate this problem by comparing different optimal models of day-ahead markets based on unit commitment (UC) formulations, especially energy-vs. power-based UC;...
Article
Full-text available
The increasing penetration of uncertain generation such as wind and solar in power systems imposes new challenges to the unit commitment (UC) problem, one of the most critical tasks in power systems operations. The two most common approaches to address these challenges-stochastic and robust optimization have drawbacks that restrict their applicatio...
Article
Full-text available
The emergence of distributed energy resources can lead to congestion in distribution grids. DC distribution grids are becoming more relevant as more sources and loads connected to the low voltage grid use dc. Bipolar dc distribution grids with asymmetric loading can experience partial congestion resulting in a nodal price difference between the two...
Article
Full-text available
Approximations made in traditional day-ahead unit commitment model formulations can result in suboptimal or even infeasible schedules for slow-start units and inaccurate predictions of actual costs and wind curtailment. With increasing wind penetration, these errors will become economically more significant. Here, we consider inaccuracies from thre...
Article
Full-text available
This paper presents the design of an energy management system (EMS) capable of forecasting photovoltaic (PV) power production and optimizing power flows between PV system, grid and battery electric vehicles (BEVs) at the workplace. The aim is to minimize charging cost while reducing energy demand from the grid by increasing PV self-consumption and...
Conference Paper
Full-text available
Private investors, flexibility, efficiency and environmental requirements from deregulated markets have led the existence and building of a significant number of combined-cycle gas turbines (CCGTs) in many power systems. These plants represent a complex optimization problem for the short-term planning unit commitment (UC) carried out by independent...
Article
Full-text available
This paper provides the convex hull description of the single thermal Unit Commitment (UC) problem with the following basic operating constraints: (1) generation limits, (2) start-up and shut-down capabilities, and (3) minimum up and down times. The proposed constraints can be used as the core of any unit commitment formulation to strengthen the lo...
Article
Full-text available
The growing increase of renewable generation worldwide is posing new challenges for a secure, reliable and economic operation of power systems. In order to face the uncertain and intermittent production of renewable sources, operating reserves must be allocated efficiently and accurately. Nowadays, these reserves are mainly assigned to thermal unit...
Article
Full-text available
This paper proposes a power-based network-constrained unit commitment (UC) model as an alternative to the traditional deterministic UCs to deal with wind generation uncertainty. The formulation draws a clear distinction between power-capacity and ramp-capability reserves to deal with wind production uncertainty. These power and ramp requirements ca...
Article
Full-text available
This paper provides the convex hull description for the basic operation of slow- and quick-start units in power-based unit commitment (UC) problems. The basic operating constraints that are modeled for both types of units are (1) generation limits and (2) minimum up and down times. Apart from this, the startup and shutdown processes are also modele...
Article
Full-text available
Private investors, flexibility, efficiency and environmental requirements from deregulated markets have led the existence and building of a significant number of combined-cycle gas turbines (CCGTs) in many power systems. These plants represent a complex optimization problem for the short-term planning unit commitment (UC) carried out by independent...
Thesis
Full-text available
In recent years, high penetration of variable generating sources, such as wind power, has challenged independent system operators (ISO) in keeping a cheap and reliable power system operation. Any deviation between expected and real wind production must be absorbed by the power system resources (reserves), which must be available and ready to be dep...
Article
Full-text available
Modeling electricity storage to address challenges and opportunities of its applications for smart grids requires inter-temporal equalities to keep track of energy content over time. Prevalently, these constraints present crucial modeling elements as to what extent energy storage applications can enhance future electric power systems' sustainabilit...
Article
Full-text available
This paper presents a Mixed-Integer Linear Programming (MILP) reformulation of the thermal Unit Commitment (UC) problem. The proposed formulation is simultaneously tight and compact. The tighter characteristic reduces the search space and the more compact characteristic increases the searching speed with which solvers explore that reduced space. Th...
Conference Paper
Full-text available
This paper presents a mixed-integer linear programming (MILP) formulation of start-up (SU) and shut-down (SD) power trajectories of thermal units. Multiple SU power-trajectories and costs are modeled according to how long the unit has been offline. The proposed formulation significantly reduces the computational burden in comparison with others com...
Article
Full-text available
The day-ahead Unit-Commitment (UC)-based Market-Clearing (MC) is widely acknowledged to be the most economically efficient mechanism for scheduling resources in power systems. In conventional UC problems, power schedules are used to represent the staircase energy schedule. However, the realizability of this schedule cannot be guaranteed due to the...
Article
Full-text available
This paper presents a Mixed-Integer Linear Programming (MILP) formulation of Start-Up (SU) & Shut-Down (SD) power trajectories of thermal units. Multiple SU powertrajectories and costs are modeled according to how long the unit has been offline. The proposed formulation significantly reduces the computational burden in comparison with others common...
Data
Full-text available
This paper reports a strategy for identifying and locating faults in a power distribution system. The strategy was based on the K-nearest neighbours technique. This technique simply helps to estimate a distance from the features used for describing a particular fault being classified to the faults presented during the training stage. If new data is...