Coordination between medium-term generation planning and short-term operation in electricity markets

This paper analyzes the coordination between medium-term generation planning and short-term operation in electricity markets. This coordination is particularly important from a practical point of view in order to guarantee that certain aspects of the operation that arise in the medium-term level are explicitly taken into account: limited-energy resources and obligatory-use resources. Three different approaches are proposed in order to guarantee that short-term decisions made by a generation company are consistent with its operation objectives formulated from a medium-term perspective. These approaches make use of technical and economic signals to coordinate both time scopes: primal information, dual information, and resource-valuation functions. This paper presents the main advantages and drawbacks of the three approaches and applies them to a case study that uses a conjectural-variation-based representation of the market.     

Variational inequalities for solving possibilistic risk-averse electricity market quilibrium

It is widely known and accepted that Nash equilibrium suitably models agents' behavior in electricity markets, since it is coherent with the common sense of their simultaneous profits maximisation. In the literature, these approaches are usually addressed using deterministic representations, despite the fact that electricity markets are highly conditioned by the uncertainty in demand or in agents' bidding strategies. Only some equilibrium-modelling approaches under uncertainty can be found in the literature, most of them using probability distributions. However, probability approaches may lead to very complex formulations and generally require restrictive assumptions (such as normality or independence) that can hardly be verified in real complex problems. A conjectured-price-response equilibrium model that uses LR-possibility distributions to represent the uncertainty of the residual demand curves faced by the participant agents is proposed. Modelling the risk-aversion attitudes of the agents, the resulting possibilistic equilibrium is transformed into a simplified deterministic one, which is solved with a new globally convergent algorithm for variational inequalities problems. Some interesting results for a real-size electricity system show the robustness of this new approach when compared with other risk-neutral approaches.     

Electricity market equilibrium based on conjectural variations

Many of the models used for the representation of the generation companies’ behavior in oligopolistic electricity markets are based on conjectural variation equilibria, which are a generalization of the classic Cournot approach. However, one of the main drawbacks of these approaches is the complexity of assigning adequate values to the conjectures, which can dramatically affect the results obtained from these models.     

Electricity tariff design for transition economies: Application to the Libyan power system

This paper presents a general electricity tariff design methodology, especially applicable for transition economies. These countries are trying to modernize their power systems from a centralized environment (with normally, a public vertically integrated electric company) to a liberalized framework (unbundling electricity companies and, eventually, starting a privatization process). Two issues arise as crucial to achieving a successful transition: i) ensuring cost recovery for all future unbundled activities (generation, transmission, distribution and retailing), and ii) sending the right price signals to electricity customers, avoiding cross-subsidies between customer categories. The design of electricity tariffs plays a pivotal role in achieving both objectives. This paper proposes a new tariff design methodology that, complying with these two aforementioned criteria, requires a low amount of information regarding system data and customer load profiles. This is important since, typically, volume and quality of data are poor in those countries. The presented methodology is applied to computing tariffs for the Libyan power system in 2006, using real data.     

Impact of the Kyoto Protocol on the Iberian Electricity Market: A scenario analysis

This paper presents an assessment of the impact of the Kyoto Protocol on the Iberian Electricity Market during two periods: the first phase (2005–2007) and the second phase (2008–2012). A market-equilibrium model is used in order to analyze different conditions faced by generation companies. Scenarios involving CO₂-emission prices, hydro conditions, demand, fuel prices and renewable generation are considered. This valuation will show the significance of CO₂-emission prices as regards Spanish and Portuguese electricity prices, generation mix, utilities profits and the total CO₂ emissions. Furthermore, the results will illustrate how energy policies implemented by regulators are critical for Spain and Portugal in order to mitigate the negative impact of the Kyoto Protocol. In conclusion, the Iberian electricity system will not be able to reach the Kyoto targets, except in very favorable conditions (CO₂-emission prices over €15/ton and the implementation of very efficient energy policies).