Dimitris I. Chatzigiannis

European Electricity Market Integration With Mixed Market Designs—Part I: Formulation

The integration of the day-ahead electricity markets in Europe shall lead to one multi-area market that will substitute the local/national ones. In view of the “target model” that will be enforced in all European markets in conjunction with their forthcoming coupling/integration, a centralized market splitting algorithm is implemented in this paper, respecting the standard market regulatory framework of power exchanges (PXs) and power pools, including 1) block offers/bids, linked block offers/bids, flexible hourly offers/bids and convertible block offers in power exchanges and 2) unit technical/commitment constraints and system operating constraints in power pools. The problem is formulated as a mixed integer linear programming (MILP) model, which can be solved using commercial MILP solvers. The performance and computational requirements of an implementation in pan-European level is presented in the companion paper; the model is tested in terms of problem solvability to its limits, considering a day-ahead market clearing time threshold equal to one hour.

European-Type Electricity Market Clearing Model Incorporating PUN Orders

A novel model for the clearing of European day-ahead electricity markets, with all associated types of orders, namely simple hourly orders, block orders, complex orders and PUN (“Prezzo Unico Nazionale”) orders is presented in this paper. An iterative algorithm is employed for the market clearing, bearing an inner iteration process for the handling of Paradoxically Accepted block and MIC orders, and an outer iteration process for the handling of PUN orders. During the iterative process a Master Problem and a PUN subproblem are sequentially solved and coordinated, for the efficient handling of all order clearing conditions and market and/or system constraints. The clearing conditions of each order type are explicitly incorporated in the PUN subproblem, formulating a Mixed Complementarity Problem bearing both primal and dual decision variables. The PUN subproblem concerns the sequential clearing of 24 hourly subproblems, employing a special technique for handling the possible inefficiencies due to the myopic nature of the hourly subproblem solutions, leading to enhanced behavior in terms of social surplus with respect to the state-of-the-art day-ahead market clearing solver. The model and the algorithmic process are evaluated in a west-European test case, demonstrating minimal computational requirements and proving its excellent escalation capabilities.

European Market Integration With Mixed Network Representation Schemes

A centralized market-splitting algorithm is implemented in this paper in a Europe-wide level, comprising both power pools and Power Exchanges, with each local/national market respecting the standard constraints imposed by its own regulatory framework, including the full set of unit technical/commitment constraints and system operating constraints in power pools. In view of the forthcoming large-scale RES penetration, physical markets with unit-based offers (either pools or PXs) check the feasibility of the electricity market solution against their internal (intra-zonal) transmission network constraints, considering full network topology. This is accomplished through an iterative process, iterating between the overall optimization algorithm, and intra-zonal power flows of the countries/regions, which identify possible congestions and incorporate additional constraints in the central pan-European market-splitting problem. The iterative process terminates when all internal transmission constraints are satisfied. Locational marginal prices (LMPs) can be computed in the physical markets, whereas zonal/system marginal prices are computed in markets with portfolio-bidding schemes. The proposed algorithm is tested in terms of computational efficiency using the full UCTE network.

Security-constrained nodal-based clearing of the European day-ahead electricity market formulated as a MILP model

In this paper a nodal-based approach is evaluated for the clearing of the pan-European day-ahead electricity market. In the proposed mathematical formulation, the widely used in European Power Exchanges (PXs) profile block orders are explicitly modeled, whereas the full set of inter-zonal and intra-zonal normal and security (N-1) transmission constraints is incorporated. The proposed approach is evaluated using a real-world power system, the Balkan power system, and the economic and computational aspects of the proposed methodology are thoroughly discussed.

European market integration with both physical and non-physical markets

In view of the forthcoming large-scale RES penetration, physical markets should check the feasibility of the electricity market clearing against their internal (intra-zonal) transmission network constraints, considering full network topology. Three methods for the solution of a market-splitting problem in a Europe-wide level are implemented in this paper. Two iterative processes are employed, iterating between the overall optimization algorithm and intra-zonal power flows of the countries/regions that identify possible internal congestions; the iterative processes terminate when all internal transmission constraints are satisfied. The results of the iterative processes are compared with the results of a one-stage solution of the overall problem, which incorporates the full set of transmission constraints of all European electricity markets. The proposed algorithms are also compared in terms of computational efficiency using the full UCTE network.

A market splitting approach for the European electricity market integration

The “Target Model” for the European electricity markets integration has received the attention of regulators, economists and market designers in the last years, namely the substitution of local electricity markets with a harmonized multi-area market, with same market segments in all European countries. In view of this market integration, a Europe-wide market-splitting model is presented in this paper, in which each national market retains its regulatory framework/design, namely remains a power pool or a Power Exchange. The developed model is tested in a Europe-wide test case, comprising three power pools and twenty two existing and prospective Power Exchanges. The model solution and the computational efficiency of the proposed implementation are presented here.

European electricity market integration under various network representations

The integration of the European electricity market constitutes a critical and contemporary issue, expected to take place within year 2015. In view of the forthcoming RES penetration, physical markets with unit-based offers-either power pools or Power Exchanges (PXs)-check the feasibility of the electricity market solution against their intra-zonal transmission capacity constraints. An iterative process is examined, with two variations, differentiating only in the way that the internal network of each physical market is represented. In each iteration of the proposed algorithm, intra-zonal power flows are calculated, possible violations of internal transmission limits are identified and additional constraints are incorporated in the centralized market splitting problem, in order to avoid the overloading of internal transmission lines. The attained results are compared to those of a centralized market-splitting problem, considering the full European network configuration. The above methods are compared in terms of (a) solution efficiency, (b) correct pricing and (c) computational efficiency.

Storage management by rolling unit commitment for high renewable energy penetration

This paper presents a deterministic unified unit commitment and economic dispatch model that integrates storage devices in the short-term power system scheduling under high renewable energy penetration. The presented model is a single multi-hour look-ahead real time tool that uses multiple time resolution to reduce its computational requirements. Operating on a rolling basis, the decisions of the first scheduling period are binding while the decisions of the remaining scheduling horizon are indicative. Adopting this approach, storage facilities can be more efficiently operated, since the problem of defining the appropriate energy level of the storage devices during economic dispatch is alleviated. The operational impact of storage is validated via extensive simulations using data from the Greek Interconnected Power System.

Large-scale res integration in electricity markets: Challenges and potential solutions

The increasing shares of renewable energy in power systems have a significant impact on the operation of electricity markets and grids worldwide. This paper provides an overview of the main challenges that high shares of renewable generation introduce in the power system management and electricity markets operation as well as a brief description of potential solutions for alleviating the negative implications caused by the large-scale renewable integration. Additionally, a summary of the core research activity that has been performed in the context of a relevant academic research project, called “Large-Scale Renewable Integration in Electricity Markets”, (acronym, “LaRInEM”) is presented and valuable conclusions regarding the efficient integration of large amounts of renewable energy in electricity markets are drawn.

Determination of load-following reserves in power systems with high wind penetration: An application to the Greek power system

This paper addresses the problem of quantifying the amount of spinning and non-spinning load-following reserves required for the normal operation of a power system under high wind penetration. A two-stage stochastic optimization problem is formulated; in the first stage the market operator clears the day-ahead market, while in the second stage the real-time operation of the power system is modeled, considering uncertainty in wind production by means of wind power generation scenarios. The required levels of load-following reserves are first-stage decisions. The proposed model is tested on the Greek power system and its economic and computational aspects are thoroughly discussed.