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Title: A mechanism for decentralized participation of flexible demand in electricity markets
Author: Papadaskalopoulos, Dimitrios
ISNI:       0000 0004 2737 2146
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2013
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In deregulated power systems, the realization of the significant demand flexibility potential should be coupled with its integration in electricity markets. The approaches examined in the available literature to achieve this paradigm change exhibit significant limitations. Centralized mechanisms raise communication and computational scalability issues as well as privacy concerns by the consumers, while dynamic pricing schemes neglect the natural interdependence between demand and prices and thus fail to realize the actual value of demand flexibility. This thesis proposes, analyzes and tests a novel pool market clearing mechanism enabling flexible demand participation in electricity markets by combining the solution optimality of centralized mechanisms with the decentralized demand participation structure of dynamic pricing schemes, and based on Lagrangian Relaxation (LR) principles. The price-response optimization problems corresponding to three flexible demand technologies with significant potential -namely electric vehicles with flexible charging capability, space-heating electric heat pumps accompanied by heat storage and wet appliances with deferrable initiation time- are mathematically formulated, incorporating detailed models of their operational properties. Non-convexities of these price-response problems and their impacts on the ability of the basic LR structure to reach feasible market solutions are identified and analyzed. An effective LR heuristic method is developed to produce both feasible and high-quality solutions, by applying a suitable relative flexibility restriction on flexible demand, in order to avoid its concentration to the same low-priced time periods, without requiring knowledge of the individual flexible loads’ characteristics. For flexible electric vehicles and electric heat pumps this restriction is associated with their maximum power demand, while for flexible wet appliances it is associated with their maximum initiation time deferrability. In the case where network constraints are included in the problem, location-specific values for this flexibility restriction are determined in order to improve the quality of the obtained solution, through an algorithm involving approximate characterization of the nodal aggregated flexible demand populations based on their price responses, in order to avoid extensive computational requirements. Finally, suitable Lagrangian multipliers update algorithms are examined in order to reduce the number of iterations and thus the communication requirements of the proposed mechanism. Extensive case studies on a model of the UK power system, with different penetration and flexibility scenarios for the three examined technologies, validate the theoretical properties of the proposed mechanism and analyze the impact of flexible demand’s market participation.
Supervisor: Strbac, Goran Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available