Transactive energy management for residential distribution networks with distributed energy resources
Modern residential buildings are now equipped with various distributed energy resources (DERs), such as roof-top solar photovoltaic, electrical energy storage systems, electric heat pumps, electric vehicles (EV) with vehicle-to-grid (V2G) functionalities, and so on. The rapid proliferation of such DERs and the introduction of demand response (DR) and Transactive Energy (TE) have transformed the traditionally passive electricity consumers into prosumers. A prosumer is a small-scale electricity producer who, in addition to consuming electricity from the grid, is capable of selling electrical energy back to the grid. DR encourages consumers to modify their demand profiles according to the need of the power grid using tariff or incentive signals. However, increasing prosumer behaviour in DR programs can introduce various capacity issues for local low-voltage (LV) residential distribution networks. In this regard, TE facilitates the effective utilisation of the demand-side flexibility by dictating the energy exchanges within the network using embedded economic signals while incorporating underlying gridconstraints. However, existing market structures of TE frameworks do not allow the active participation of small-scale residential prosumers without leveraging their profitability, autonomy, decision-making authority, and privacy. This necessitates effective transactive energy management (TEM) methodologies with adequate market frameworks to ensure active consumer participation in power grid services. This dissertation presents four innovative contributions towards analysing the demand-side flexibility potential of residential prosumers and developing comprehensive TEM methodologies for DER-integrated LV residential distribution networks for the effective utilisation of demand-side flexibility to address grid issues of capacity-constrained local networks.
The first contribution of this research is the development of a home energy management system (HEMS) with an optimised bidding strategy for bidirectional electricity trading, which is commonly pertinent to DR and TE schemes. The proposed HEMS schedules energy uses in the building according to a twostage stochastic bi-level optimisation model and determines energy-trading bids by minimising energy cost, storage degradation, thermal discomfort, and user inconvenience.
The second contribution is the design and implementation of a local transactive market-based TEM framework for DER-integrated residential neighbourhoods. The proposed framework allows residential prosumers to trade their flexibility among themselves and with the local grid operator, who procures demandside flexibility from the market to prevent local transformer overloading. The decentralised coordination is realised using a multi-agent system (MAS)-based architecture to ensure prosumers’ autonomy and privacy.
This third contribution of this research is to establish a MAS-based coordinated EV management system to address the overloading and voltage-constraint violations of LV residential networks. The proposed methodology offers EV owners autonomy and minimises their costs without the need for an energy management system with complex computational capability. On the other hand, it prevents local grid overloading and under-voltage situations by using the V2G flexibility of the EVs without violating their operational constraints and the preferences of the owners.
The final contribution of this research is to design and implement a nested TE market framework to integrate the local flexibility markets with the wholesale demand response market. The optimised bidding model and market mechanisms are developed for the local and wholesale markets to maximise profits for all involved parties, such as the prosumers, local grid operators, flexibility aggregators, and the wholesale market operator. The proposed methodology enhances the utilisation of demand-side flexibility for mitigating local grid overloading and reducing wholesale price-spikes during grid emergencies while offering significant financial profits for the participating prosumers.
Extensive case studies are performed considering actual residential demand profiles, solar PV generations, EV usage data, and electricity market structures for residential prosumers in Sydney, Australia. Detailed analyses of the results are presented, and the performance of the proposed methodologies are compared with the state-of-the-art methods. The results indicate the efficacy of the proposed methodologies for the effective and economic utilisation of demand-side flexibility for mitigating local grid issues, such as overloading and voltage-constraints violations. Also, the results of the case studies indicate that the proposed market frameworks of the TEM methodologies offer significant cost savings for residential prosumers without affecting their privacy, autonomy, decision-making authority, preference, comfort, or convenience.