Juan D. Molina

Transmission of Electric Energy: a Bibliographic Review

The reforms carried out in various energy markets assign a central place to the transmission and hence this has created a dynamic research area, which is reported in this paper. There are various research topics, so it is required to identify the different areas and scientific advances in the field. Setting the types of assumptions used in the models and the influence of dynamic variables such as generation, demand and flow control will allow a better understanding of market dynamics. A comprehensive literature review is performed and in a context of power markets the most recent and relevant research in the evolution of the transmission is assessed. The paper presents topics of economic regulation and market mechanisms, planning, financial assessment, assignment, network congestion, economic and technical modeling methods and the influence of transmission technologies in the energy market. Research has sought to provide coupling mechanisms between economic and technical concepts, in order to provide feasible solutions to the electricity market. The debate about which is the best mechanism for the regulation of transmission, the planning model and the allocation of transmission costs, are still in force. The new contributions are focused on the impact of transmission on the market and the social benefits of the proposed mechanisms for transmission expansion.

Transmission expansion plan: Ordinal and metaheuristic multiobjective optimization

Electric energy transmission is essential for the operation of competitive energy markets. Transmission expansion planning has been defined as a complex combinatorial optimization problem. This work puts forward a description of the solution techniques and alternatives to implement the transmission systems expansion. A model that considers Multi-objective Optimization - MOO - criteria is proposed under the concepts of Tabu Search - TS - Ordinal Optimization - OO - and Pareto optimality. The model proposed generates expansion plans under the Pareto optimality approach. It shows acceptable solutions under robustness and algorithmic speed criteria. The results obtained in the test systems show that the model developed is effective to find the solution for the combinatorial problem. Multi-objective optimization defines a set of feasible solutions that establishes expansion plans scenarios.

A Principal-Agent Approach to Transmission Expansion—Part I: Regulatory Framework

Different regulatory frameworks have implemented competitive mechanisms to increase efficiency in transmission, a natural monopoly. Conflicts of interest and hidden costs make necessary to define methods to obtain an appropriate valuation of new transmission assets. This paper is the first one of a two-paper series and presents the fundamentals of transmission project valuation and cost allocation. We show the fundamentals of non-cooperative game theory, different concepts of game equilibria (Nash, Stackelberg, and Berge), and solutions to the bilateral negotiation problem (Nash bargaining solution, Kalai-Smorodinsky, and Rubinstein). In addition, the design of mechanisms, the information revelation principles, and incentive compatibility issues are described. We propose a model composed of three elements: valuation of a transmission project based on a linear contract, a principal-agent model to determine the optimal effort of an agent developing the transmission project, and the optimal bilateral negotiation of right-of-way costs. We define a method to evaluate the offers to build a transmission line project as a function of the number of agents bidding for it. The value of the project is a function of both the incentives and the valuation of the right-of-way costs. In part two of this series, we present two case studies: the IEEE 24-bus RTS and the Sistema Interconectado Central (SIC) in Chile, where we apply the methodology to a real network.

Pronóstico del Precio de la Energía Eléctrica usando Redes Neuro-Difusas

Resumen Se propone un modelo para el pronostico del precio de la energia electrica en Colombia mediante el uso de redes neuro-difusas. Se utilizan dos estructuras de redes incluyendo como entradas la serie de precios diarios en la primera y la serie de precios mas el nivel medio de los embalses en la segunda. Los resultados son comparados con dos estructuras de redes neuronales y con un modelo Autoregresivo Condicional Heterocedastico Generalizado (GARCH). Los datos historicos fueron obtenidos de la Compania XM del Grupo ISA; datos para 120 dias son usados para entrenamiento y los 31 dias siguientes para verificar la capacidad predictiva del modelo. Se encontro ventajas en este ultimo dentro del periodo de muestreo para una variable de entrada, pero un mejor desempeno de las redes neuro-difusas en el periodo fuera de la muestra tanto para una como para dos variables de entrada. Palabras clave: precio de la electricidad, redes neuronales artificiales, redes neuro-difusas, modelos de series de tiempo

A Risk-Constrained Project Portfolio in Centralized Transmission Expansion Planning

The implementation of a centralized transmission expansion plan is a complex task when several investors compete and bid to build a new transmission asset, as is the case now in Chile. The assessment of a transmission project depends on the number of competitors, where the project is subject to risks, such as delays, penalties, and cost overruns. The risk faced by an investor is measured using the Conditional Value at Risk (CVaR), which can be interpreted as the risk of not reaching an expected return on investment, depending on the tolerance to risk and the real income obtained with the investors portfolio. This risk comes from the difference between the regulated income (investors bid) and the real cost during the implementation and operation of the transmission project. The difference is the “surplus” profit that the investor obtains by participating in the tender, considering their risk tolerance. The goal is to determine the optimal value of a risky investors portfolio made up of several transmission projects. The optimal portfolio may allow the central planner to improve the efficiency of the project allocation process. To test the methodology, two case studies are analyzed: the IEEE 24-bus Reliability Test System and a predefined expansion plan of Chiles Central Interconnected System (SIC).

Technological impact of non-conventional renewable energy in the Chilean electricity system

Renewable energy has had a steady growth in power systems worldwide. The high uncertainty about what type of renewable technology meets technical and economic variables of the energy markets and what could be the participation in the energy matrix are important long term energy planning challenges that need to be identified and evaluated. This work assesses different scenarios of future development of the Chilean electricity matrix and the technological contribution of renewables. They are formulated within the Chilean Central Interconnected System and determine the evolution of technological diversity variables, costs, CO2 emissions and energy injection. The scenarios illustrate the need to strengthen the transmission system and the importance of improving and / or incorporating mechanisms to reduce dependence on fossil fuels and the maximization of renewable resources in Chile. Future work will establish the impact of intermittent renewable technologies on power system operation.

Power asset management: Methods and experiences in Colombian power system

Results of a review of the literature on asset management in the electricity sector is presented, as well as a glance at some progress on it in Colombia. Such results can serve as a reference for the development of tools that strengthen the implementation of asset management systems in the electricity industry, as well as help to identify shortcomings in the methodologies in use today in Colombia. A proper management of power assets is of paramount importance, especially since such assets are characterized by high capital costs and also by the high economic losses that are faced when assets fail. The review focuses on the power transformer given the characteristics which make it a strategic asset in the management of the power system. It is concluded that the adoption of policies and techniques of asset management is of strategic importance for the electricity sector, and that there are general and specific guidelines provided by worldwide acknowledged organizations and they are being assimilated and implemented by large electric power companies in Colombia.

A Principal-Agent Approach to Transmission Expansion—Part II: Case Studies

This paper is the second of a two-paper series and presents a model to assess and promote investment projects defined in a plan of expansion of the transmission. We propose a model that consists of three main elements: valuation of a project based on the design of a linear contract, a principal-agent model to assess the optimal effort of an agent, and the right-of-way negotiating cost. We also define a model to evaluate bids by the agents. The value of the project depends on the number of competitors, the incentives to invest, and the right-of-way costs. The right-of-way cost is approached from the perspective of a bilateral bargaining problem.

Approaches to transmission planning: A transmission expansion game

Defining and making decisions about network investments has become a hard task in a competitive environment. This work defines a methodology to look for expansion alternatives in a transmission system. We propose a Transmission Expansion Game model that consists of four main elements: i) generating transmission expansion plan scenarios, ii) valuation of a project based on the design of a linear contract, bargaining solutions and hidden actions, iii) optimal value of a risky investors portfolio made up of several projects, and iv) transmission cost allocation with wind energy assets. The results obtained show that the model developed is efficient to solve the combinatorial problem. A principal-agent model obtains the real costs of the bidders and creates incentives for disclosure of information. The private optimal portfolio and bargaining for allocation cost gives evidence for the central planner to adjust the project assignment process and to carry out the proposed expansion plan efficiently. To test the methodology we analyze the Chilean Central Interconnected System.

Renewable energy integration: Mechanism for investment on bulk power transmission

Transmission has established itself as a natural monopoly, and as such, the prices and remaining access and operating conditions of the transmission system have been regulated. In the regulations existing before the electric sector reform there was a single planner that determined the generation and transmission expansion. However, each time more mechanisms have been implemented that have allowed individualizing the agents of interest and as such, uncoupling planning and investment from the power plants and grids. This has brought a problem based on the optimal and timely investment on grids, mainly when power injection is considered with high uncertainty, as it usually happens with renewable energies.