• Energy Research

The large penetration of renewable energy resources is demanding additional flexibility for the operation of power systems. In this sense, real world applications are proving that wind power units are able to provide part of the required flexibility. Therefore, these new sources of flexibility need to be considered by power system planners in order to make appropriate generation capacity expansion decisions. This paper proposes a generation and storage capacity expansion formulation considering that wind power units are able to participate in the reserve provision service. The proposed model is a stochastic linear program that is solved using a commercial solver. A case study based on the isolated power system of Lanzarote and Fuerteventura in Spain is solved to quantify the impact of considering the reserve provision of wind power in capacity investment decisions.

This paper proposes a simple multiarea decentralized state estimation procedure. This procedure allows estimating the state of a multiarea electric energy system while preserving the independence of each area. Information interchange among area operators reduces to just border information. The proposed algorithm is both simple and robust. The procedure developed is illustrated through several case studies carried out using the IEEE Reliability Test System. Conclusions are duly drawn

Abstract This work presents a comprehensive study of the performance of six large photovoltaic (PV) power plants with different mounting topologies over several years of operation. This is a marked contrast to most available performance studies which focus on the study of a single installation of low rated power and one mounting type. The performance results are obtained following the guidelines of Standard IEC 61724 and largely coincide with those expected considering the plants’ location in the South-Central Region of Spain, with a total system efficiency ranging between 10% and 12%. Moreover, some performance trends are identified and associated with mounting system, size and location. Finally, it is concluded that the added complexity of dual-axis tracking systems in the operation and maintenance was underestimated in the design phase of the PV power plants. Wind speed has emerged as a key parameter, not only due to the cooling effect on the PV panels but also as a result of its impact on the availability of energy generation.

Reactive power must be measured and watched to verify accomplishment of Spanish grid code requirements in wind farms. However, no definition of reactive power is established in that code. Thus, two reactive power formulations are compared in this paper applied to wind farm generators in presence of transient disturbances such as voltage dips. First reactive power formulation is based on Emanuel's approach, included in the IEEE Standard 1459-2000. Second reactive power formulation has recently been established by Czarnecki. Both formulations express reactive power decomposed into the reactive power due to the reactances and the reactive power caused by the unbalances. This decomposition allows for a better knowledge of wind farms working and to verify the accomplishment of code grids established in several countries.

In this paper, we analyze the generation, storage and transmission expansion of the isolated power system of Las Palmas (Spain) for 2050. This power system comprises two isolated systems: Lanzarote-Fuerteventura and Gran Canaria. The generating, storage and transmission capacity to be built is determined by solving a two-stage stochastic investment model taking into account different long-term uncertain parameters: investment costs of immature technologies of power production and storage, annual demand growth, number of electric vehicles, rooftop solar penetration and natural gas prices. The possibility of linking together the isolated power systems of Lanzarote-Fuerteventura and Gran Canaria for reaching a higher penetration of renewable units is also considered. The operation of the power system is simulated by considering the day-ahead energy and reserve capacity markets. The variability of the hourly available wind and solar power, and the demand level are modeled by using a set of characteristic days to represent the target year. The performance of the resulting power system is assessed by conducting an out-of-sample analysis using the AC model of the power system. The numerical results show that a future configuration of Las Palmas power system mainly based on solar and wind power units can be achieved with the support of gas units and storage.

The incorporation of renewable energy sources in isolated power systems is being significantly slower than in well-connected power systems. The intermittency and uncertainty of the power output of most renewable power technologies prevent a greater usage of these technologies in isolated power systems, in which the supply security is the major concern. In this paper we formulate a stochastic unit commitment problem that allows the participation of electric vehicles in energy, reserve capacity and primary frequency response markets in order to increase the flexibility of the power system operation. We explicitly consider the uncertainty in the power demand and renewable power availability, as well as accounting for the possibilities of contingencies of generating units using a N-1 security criterion. The proposed formulation is tested on an actual isolated power system comprising 38 generating units and 8 buses.

Ancillary services are intended to ensure the quality, reliability, and security conditions of the electricity supply. Active power‐related ancillary services are considered balancing services, including mandatory services, such as spinning or primary regulation, and optional services, such as secondary and tertiary regulation. These optional balancing services have typically been supplied by conventional power plants, but since their contribution to the production share is decreasing due to high renewable energy penetration, power system operators are currently in need of alternatives. In addition, the recent advances in both the wind power industry and power system observability and controllability, and the necessary changes in balancing markets have made it technically and economically possible for wind power plants to contribute to optional balancing services. Under this framework, our study focuses on the contribution of wind power to balancing markets in the Spanish power system. Specifically, this work analyses the operational capability test for wind energy active power ancillary services provision and the results of the participation of wind energy to tertiary regulation and imbalance management from February 2016 to July 2017. Furthermore, the analysis includes a comparison with other generation technologies and the identification of upward and downward direction margins. These results show the real experience of the contribution of Spanish wind energy to optional active power ancillary services.This article is categorized under: Wind Power > Systems and Infrastructure

The design of future decarbonized power systems is one of the most relevant and challenging problems that power system planners are facing nowadays. It is expected that Combined-Cycle Gas Turbines (CCGTs) play a relevant role in these systems to provide peak power and reserve capacity when intermittent power units be unavailable. However, the large computational size of planning problems has prevented so far from modeling the actual operation of CCGTs accurately. This paper intends to quantify the effect of the modeling of CCGTs in the generation capacity expansion problem. For doing that, the operation of CCGTs is modeled using a mixed-integer linear formulation that considers different operation modes. Afterwards, generation expansion decisions in a realistic case study are analyzed using different accuracy degrees for modeling the operation of CCGTs. The numerical results suggest that the simplification of the modeling of the operation of CCGTs overestimates the flexibility provided by these units, which increases the capacity installed from renewable units between 15 and 25%.