Kristin Dietrich

Demand Response in an Isolated System With High Wind Integration

Growing load factors in winter and summer peaks are a serious problem faced by the Spanish electric energy system. This has led to the extensive use of peak load plants and thus to higher costs for the whole system. Wind energy represents a strongly increasing percentage of overall electricity production, but wind normally does not follow the typical demand profile. As generation flexibility is limited due to technical restrictions, and in absence of large energy storages, the other side of the equilibrium generation-demand has to react. Demand side management measures intend to adapt the demand profile to the situation in the system. In this paper, the operation of an electric system with high wind penetration is modeled by means of a unit commitment problem. Demand shifting and peak shaving are considered in this operation problem. Demand shifting is modeled in two different ways. Firstly, the system operator controls the shift of demand; secondly, each consumer decides its reaction to prices depending on its elasticity. The model is applied to the isolated power system of Gran Canaria. The impact of an increased installed wind capacity on operation and the cost savings resulting from the introduction of responsive demand are assessed. Furthermore, results from the different implemented demand response options are compared.

Demand response and its sensitivity to participation rates and elasticities

Activating the demand-side of the electric system is a comeback of an old idea. What decades ago did not work out due to the lack of proper technology, today raises hopes to meliorate some of the most problematic situations in electric system operation such as ever higher peak demands and high wind generation during low demand periods. Smart grid infrastructures are currently implemented in many countries. This communication and control infrastructure allows consumers to receive information on system conditions, for example in the form of price signals, and thus to react to these and reduce, increase or shift their electricity consumption. This paper presents the modelling of demand shifting with two Demand Response mechanisms, Direct Load Control and Dynamic pricing. The outcome of both mechanisms depends, to a great extent, on two parameters: the maximum share of load which consumers are able and willing to shift and the elasticities used to express consumers level of responsiveness in the dynamic pricing mechanism. An analysis of the sensitivity of the impact of Demand Response is carried out by varying these two parameters over a large range. Results regarding demand participation shares, cost savings, demand variation patterns and used generation technologies are compared for the different sensitivity cases. We find that cost saving increases are not proportional to increments in the maximum share of participating demand and in responsiveness to prices.

Storage systems for integrating wind and solar energy in Spain

Renewable energies are on the rise in many countries. Mainly due to environmental concerns they have obtained the political support and are fostered in a large number of countries. Among the technologies which have experienced the highest rise are intermittent generation technologies which are variable and uncertain in their electricity production, such as those using wind or solar power. These characteristics require a radical change of the way electricity energy systems are organized nowadays. More flexibility is needed to adapt to these fluctuating and only to a certain extent controllable energy technologies. Storage systems offer perfect conditions for the integration of these intermittent energy sources. Electricity generation surplus from these technologies can be stored and injected into the electricity system later when demand or prices are higher. Investigation in new storage systems is necessary to analyse which storage systems may adapt best to this type of fluctuating production. This article aims to compare some already mature storage technologies and their impact on the integration of renewable energies in the operation of the electric system. In specific, we will analyse the following four storage technologies: pumped hydro storage, compressed air energy storage, heat storage in combination with concentrated solar power and lithium-ion batteries which are operated stationary as well as in electric vehicles. Cost savings, emission reductions and the effect on the production of other generation technologies will be observed.

The Role of Flexible Demands in Smart Energy Systems

The demand side of the electricity system holds a flexibility resource which has been ignored for a long time. With the presence of smart grids and facing challenges such as the massive integration of renewable energies into the system, demand side measures become viable and indispensable. This chapter will give a brief introduction about the concept of demand response. It will give an overview on demand response mechanisms, their objectives and potentials. Furthermore, an overview about various flexible demands in households, commerce and industries is given.

An application of the Aumann-Shapley approach to the calculation of inter TSO compensations in the UCTE system

Calculating Inter TSO Compensations (ITC) has turned out to be a highly critical issue in facilitating the formation of a competitive Internal Electricity Market in Europe. Plenty of methods have been proposed to calculate ITCs, but few of them have the features that are required, namely fairness, transparency and reasonability of their results. This article presents the Aumann-Shapley approach to calculate the compensations for the use of networks by cross-border flows. Using the fundamentals of game theory, the Aumann-Shapley approach lets agents themselves choose the most appropiate generation-load counterpart and thus minimizes at the same time individual and global network usage. A numerical example involving a large fractione of the UCTE grid (17 countries) demonstrates the functioning of the proposed method and its suitability for its implementation in the European context.

Analysis of the Impact of Increasing Shares of Electric Vehicles on the Integration of RES Generation

This chapter analyzes the medium-term operation of a power system in several future scenarios that differ in the level of penetration of electric vehicles (EVs) and how renewable energy sources (RES) can be safely integrated in the former. The analysis is performed for different vehicle charging strategies (namely dumb, multi-tariff, and smart). The analysis is based on results produced by an operation model of the electric power system where the charging of EVs is being considered. Vehicles are regarded as additional loads whose features depend on the mobility pattern. The operation model employed is a combination of an optimization-based planning problem used to determine the optimal day-ahead system operation and a Monte Carlo simulation to consider the stochastic events that may happen after the planning step. The Spanish electric system deemed to exist in 2020 is used as the base-case study for conducting the numerical analyses. Relationships among the share of EVs (relative to the overall number of vehicles), the amount of RES generation integrated, and relevant system performance indicators, such as operation cost, reliability measures, and RES curtailment, are derived in the case study section.