João Santana

Data Mining Contributions to Characterize MV Consumers and to Improve the Suppliers-Consumers Settlements

This paper deals with the establishment of a characterization methodology of electric power profiles of medium voltage (MV) consumers. The characterization is supported on the data base knowledge discovery process (KDD). Data Mining techniques are used with the purpose of obtaining typical load profiles of MV customers and specific knowledge of their customers consumption habits. In order to form the different customers classes and to find a set of representative consumption patterns, a hierarchical clustering algorithm and a clustering ensemble combination approach (WEACS) are used. Taking into account the typical consumption profile of the class to which the customers belong, new tariff options were defined and new energy coefficients prices were proposed. Finally, and with the results obtained, the consequences that these will have in the interaction between customer and electric power suppliers are analyzed.

Agent-Based Simulation of Wholesale Energy Markets: A Case Study on Renewable Generation

Variable generation (VG), such as wind power, has increased significantly in recent years. VG has several unique characteristics compared to those of traditional power plants, including significant fixed capital costs but near-zero variable production costs. Large penetrations of VG tend to influence the prices and schedules of energy markets. Specifically, increasing levels of VG tend to reduce market prices, increase price volatility, and reduce the cleared energy levels of existing generating plants. This paper describes some important features of an agent-based system to simulate energy markets. Special attention is devoted to a case study aiming at analysing the behaviour of the system in situations with increasing levels of wind generation, notably comparing market schedules and prices in situations with either low or high levels of wind generation.

Multi-agent retail energy markets: Bilateral contracting and coalitions of end-use customers

The electricity industry has undergone enormous changes and market forces drive now the price of energy. This paper focuses on retail markets in which end-use customers can choose their supplier from competing electricity retailers. Most retailers negotiate the terms and conditions of electricity contracts directly with end-use customers, although they often oversimplify or ignore classical pricing policies encouraging discounts on quantity. This work aims at using autonomous software agents to help manage the complexity of retail markets. A particular end-use customer agent can negotiate a forward contract directly with a single retailer agent. More importantly, two or more end-use customers can ally into coalitions to strengthen their bargaining positions and negotiate better agreements. This paper presents several key features of software agents able to ally into coalitions and negotiate the terms and conditions of forward contracts. It also describes a case study involving a retailer agent and a coalition of three large industrial customers negotiating a three-rate tariff. The results indicate that coalition formation is beneficial to end-use customers - that is, the price agreed in the forward contract is more favorable to these agents.

Dynamic behavior of two power supplies for FFC NMR relaxometers

The main power supply of a FFC NMR relaxometer can be based on different topologies. Its design has been done having as a basic reference the parameters of a magnet specially designed and optimized, and the magnet current that is needed to achieve a magnetic induction of 0.2 T. Due to the particularities of this magnet, the FFC power supplies must have characteristics that are not fulfilled by the most common commercial power supplies, as FFC NMR power sources generally behave as current sources that should be able to drive cycling currents with slew rates lower than 3 A/ms. In this paper, the design and dynamic characteristics of two solutions for the power supply are presented and assessed. One solution uses an additional auxiliary power supply that is replaced by a capacitor in the other solution. To guarantee the required current slew rates, the possibility of using resistors to dissipate the energy stored in the magnet is also discussed. In addition, the performance of both topologies is also presented with attention to the fact that the resistance of the magnet is not constant..

Multi-agent Electricity Markets: A Case Study on Contracts for Difference

Electricity markets (EMs) are a complex evolving reality -- new players and new business models are emerging and market rules are constantly changing. As EMs continue to evolve, there is a growing need for advanced modeling approaches that simulate the behavior of market participants, particularly how they may react to the economic, financial and regulatory changes that can occur in the environments in which they operate. This article presents several key features of software agents able to negotiate bilateral contracts in EMs, paying special attention to risk management, forward contracts and contracts for difference (CFDs). Also, it describes a set of case studies aiming at assessing the performance of CFDs as a risk management tool and comparing their performance to forward bilateral contracts.

Agent-Based Simulation of Day-Ahead Energy Markets: Impact of Forecast Uncertainty and Market Closing Time on Energy Prices

This article uses an agent-based system to analyzethe potential impact of variable generation on wholesale electricity markets. In particular, it presents a case study to analyse the impact of both wind forecast errors and high levels of wind generation on the outcomes of the day-ahead market. The case study involves six representative days and three simulations (for each day): a base case, where the market closes at 12:00 noon and the bids of a wind producer agent are based on a forecast performed 12 to 36 hours ahead, an updated forecast case, where the market closes at 8:00 p.m., and a perfect case, where production data is offered. The simulation results indicate that wind power forecast uncertainty may influence market-clearing prices, highlighting the importance of potential adaptations to the day-ahead closing time.

Design of Current Power Sources for a FFC NMR Apparatus: A Comparison

The power supply of a Fast Field Cycling Nuclear Magnetic Resonance apparatus is typically a current power source, with characteristics that are not fulfilled by most of the commercially available power supplies. This current source is used to supply a specially designed magnet, and should be able to drive a cycling current with a slew rate lower than 3 A/ms. In this paper, two solutions for this current source are designed and discussed. The first uses two power supplies: the main voltage source and an auxiliary power supply to guarantee the current transitions from the low level to the high level. In the second solution the auxiliary power supply is replaced by a capacitor. To guarantee the required current slew rates, the possibility of using resistors to dissipate the energy stored in the magnet is also discussed.

A Framework for Agent-Based Electricity Markets: Preliminary Report

The electricity industry has evolved to open marketsthat promote competition among suppliers and provide consumers with a choice of services. Most energy markets (EMs) were, however, designed without the notion that a significant part of the traded power could come from renewable energy sources, and may require modifications to continue functioning effectively. Agent-based modeling and simulation (ABMS) presents itself as a promising approach to accurately model the behavior of EMs over time. This article claims that the development of a conceptual framework to define the key features that are needed to model and simulate EMs using software agents can be an important step to assess progress in the field and highlight new avenues to explore. As a first step in this direction, it describes a category of dimensions, labeled market architecture, of a conceptual framework for agent-based electricity markets.

Sliding Mode Control of Unified Power Quality Conditioner for 3 Phase 4 Wire Systems

This paper presents the sliding mode control (SMC) of unified power quality conditioners (UPQC) intended to compensate power quality issues in three-phase four-wires systems. The SMC UPQC can be applied in electrical grids or isolated grids to mitigate power quality problems at the consumer facilities and also to minimize issues for the grid supplier. The UPQC is configured as a shunt-series filter. The shunt Active Power Filter (APF) uses a three-phase rectifier with SMC to enforce sinusoidal mains currents. The series APF uses three single-phase H-bridge inverters and SMC to improve the voltage quality at the point of common coupling. SMC design, analysis and simulation results are presented and discussed.

Renewable Generation, Support Policies and the Merit Order Effect: A Comprehensive Overview and the Case of Wind Power in Portugal

The growth of wind power generation over the past decade has surpassed all expectations. The cost of the wind energy support policy was, however, quite significant and to a large extent has led to somewhat intensive debates. The merit order effect (MOE) is an important aspect to be considered in all debates, albeit sometimes oversimplified or even ignored. Accordingly, the central goal of this chapter is to analyze and quantify the reduction in the Portuguese day-ahead market prices achieved by wind power as a result of the MOE in the first half of 2016. The results generated by an agent-based simulation tool, called MATREM, indicate a price reduction of about 17 €/MWh for the entire study period. The (total) financial volume of the MOE reached the considerable value of 391.055 million €. Especially noteworthy is the net cost of the wind energy support policy, which takes into account the feed-in tariff, the market value of the wind electricity, and the financial volume of the MOE. This cost reached the value of (-8.248) million € in January 2016, a negative value, indicating that a net profit has occurred in the month. The (total) net cost was 69.011 million € during the study period. Although considerable, this cost should be interpreted carefully, since it did not take into account the interaction of wind generation with the climate policy and the EU emission trading system (i.e., the carbon price effect on the electricity market).