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Publications

Publications by CPES

2022

Network-secure bidding strategy for aggregators under uncertainty

Authors
Iria, J; Coelho, A; Soares, F;

Publication
SUSTAINABLE ENERGY GRIDS & NETWORKS

Abstract
The widespread adoption of distributed energy resources (DER) is creating an opportunity for aggregators to transform DER flexibility into electricity market services. In a scenario of high DER integration, aggregators will need to coordinate the optimisation of DER with the distribution system operator (DSO) in order to avoid congestion and voltage incursions in the distribution networks. This coordination task is notably complex since both network and DER operation are impacted by multiple sources of uncertainty. To address these challenges, this paper proposes a new bidding strategy for aggregators of prosumers to make robust network-secure bidding decisions in day-ahead energy and reserve markets. The bidding strategy computes robust network-secure bids without jeopardising the data privacy of aggregators and the DSO. The data privacy is preserved by using the alternating direction method of multipliers (ADMM) to decompose a stochastic network-secure bidding problem into bidding and network subproblems and solve them separately and in parallel. The uncertainty of the prosumers is incorporated in the bidding problem through scenarios of load, renewable generation, and DER preferences. Our experiments show that the proposed bidding strategy computes robust bids against distribution network problems, outperforming deterministic and stochastic state-of-the-art bidding strategies in terms of cost and network observability.

2022

Using Virtual Choreographies to Identify Office Users' Behaviors to Target Behavior Change Based on Their Potential to Impact Energy Consumption

Authors
Cassola, F; Morgado, L; Coelho, A; Paredes, H; Barbosa, A; Tavares, H; Soares, F;

Publication
ENERGIES

Abstract
Reducing office buildings' energy consumption can contribute significantly towards carbon reduction commitments since it represents similar to 40% of total energy consumption. Major components of this are lighting, electrical equipment, heating, and central cooling systems. Solid evidence demonstrates that individual occupants' behaviors impact these energy consumption components. In this work, we propose the methodology of using virtual choreographies to identify and prioritize behavior-change interventions for office users based on the potential impact of specific behaviors on energy consumption. We studied the energy-related office behaviors of individuals by combining three sources of data: direct observations, electricity meters, and computer logs. Data show that there are behaviors with significant consumption impact but with little potential for behavioral change, while other behaviors have substantial potential for lowering energy consumption via behavioral change.

2022

Using Virtual Choreographies to Identify Office Users’ Behaviour-Change Priorities with Greater Impact Potential on Energy Consumption

Authors
Cassola, F; Morgado, L; Coelho, A; Paredes, H; Barbosa, A; Tavares, H; Soares, F;

Publication

Abstract
Reducing office buildings’ energy consumption can contribute significantly towards carbon reduction commitments since it represents 10% of total energy consumption. Major components are lighting (40% of consumption), electrical equipment (35%), and heating and central cooling systems (25\%). Occupants’ behaviours impact these energy consumption components, with solid evidence on the role of individual behaviours. In this work, we propose a methodology that uses virtual choreographies to identify and prioritize behaviour-change interventions towards office users based on the potential impact on energy consumption. The data shows that some behaviours with significant consumption have little potential for behavioural change impact, while other behaviours hold substantial potential for lowering energy consumption via behavioural change.

2022

Requirements for New Grid Codes: A Review in Spain & Portugal

Authors
Villena Ruiz, R; Silva, B; Honrubia Escribano, A; Gómez Lázaro, E;

Publication
Renewable Energy and Power Quality Journal

Abstract
To continue to make successful progress towards the achievement of net zero emissions by 2050, a significant number of new facilities based on renewable technologies must continue to be deployed at large scale. However, the integration of large capacities of renewable generation sources into power systems leads to a series of challenges that must be urgently addressed. On the one hand, the intermittent character of renewable resources may lead to imbalances between generation and demand curves, and on the other hand, transmission and distribution system operators will have to carefully consider the impact of reduced power system inertia due to the increase in the number of renewable power plants. Under this framework, stricter technical requirements will be demanded to new power plants that will be integrated into the grid to guarantee quality of electricity supply. These requirements are included within increasingly modern and up-to-date network connection-or grid-codes. Thus, grid codes have a significant role to play in the years to come towards the transition of a more sustainable future, and therefore this paper presents an overview of two grid codes for connecting new generation units across Europe, focusing on the current situation of Iberia. A special emphasis is given on the detailing of certain grid code requirements based on a comparison between the Portuguese and the Spanish grid codes, together with few highlights on the operational procedures for connecting new generation units on both regions. © 2022, European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ). All rights reserved.

2022

Greater than the sum: On regulating innovation in electricity distribution networks with externalities

Authors
Marques, V; Costa, PM; Bento, N;

Publication
UTILITIES POLICY

Abstract
To modernize distribution networks and enable the energy transition, we need to understand the most appro-priate regulatory approach. A set of new technologies with positive externalities challenge the traditional reg-ulatory models. We develop a decision model to assess firms' incentives to invest in new technologies under different regulatory schemes that consider externality effects. Results show that regulatory schemes under which companies retain the gains (or losses) of achieving (or not) efficiency targets more effectively promote inno-vation investments that reduce network costs. However, a case-by-case approach should be preferred for tech-nologies whose benefits go mostly beyond the network activities.

2022

Improvement of Steady State Performance of Voltage Control in Switched Reluctance Generator: Experimental Validation

Authors
Touati, Z; Pereira, M; Araujo, RE; Khedher, A;

Publication
MACHINES

Abstract
This paper presents a voltage control approach to a Switched Reluctance Generator (SRG) using a Proportional Integral (PI) controller. The principle of operation is described and the considerations in the design of controller are discussed. A current loop transfer function of an SRG with power converter has been systematically derived in order to obtain a small-signal model for the generator. The generated voltage is controlled by manipulation of the setpoint of the current control of the generator. The entire voltage loop controller and current control have been simulated and tested with a 250 W SRG prototype. The control law of the control system was implemented on a digital signal processor (TMS320F28379D). To verify the feasibility of the proposed voltage control, the performances are evaluated by numerical simulations and experimental tests with an 8/6 SRG for different rotational speeds and resistive loads. Experimental results demonstrate that the DC output voltage from SRG can be controlled well using a simple linear controller.

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