Assessing the Flexibility of Demand Response and Sector Coupling for Efficient Power System Integration of Variable Renewable Generation

Abstract

Due to the rising concerns on global warming, renewable electricity generation is expected to form a considerable share in the future generation assortment worldwide. Given the fluctuating nature of renewable energy sources (RESs), their integration would adversely affect the power system balance. Addressing this challenge requires smart and flexible solutions. Demand response (DR) is a cost-effective load shaping tool that can follow the intermittent generation profile. The associated benefits can be stepped up by using excess renewable generation for the cross-sectoral integration, such as the power to heat (P2H) coupling that has the advantage of mitigating carbon emissions in both electricity and district heat (DH) sub-sectors.

The objective of this dissertation is to assess the potential advantages offered by DR of thermostatically controlled loads (TCLs), P2H coupling and their tandem for efficient RESs integration. The goal of the dissertation is segmented into four major tasks. A comprehensive realization of the up- and down-ramping of TCLs is studied in the first task considering comfort priorities. The second task proposes an aggregator-oriented framework directed towards minimizing power imbalances and operating costs in a microgrid through thermostatic load management. The third task establishes a unique tool to optimize P2H coupling by harnessing the DR of HVAC loads in a housing community. Finally, the last task proposes a generic framework for the system-wide coupling among electricity, DH, and transport sub-sectors by utilizing the flexibility of the DH system to mitigate carbon emissions.

To fulfil the objectives, the proposed models are simulated considering Finnish systems. The following deductions can be drawn from the results. The flexibility of TCLs is constrained by the load ratings, thermal comfort choices and respective demands. Activating DR substantially reduces power imbalances and operational costs. It is also revealed that mitigating curtailments and emissions by employing a deep borehole for P2H coupling is value-added under DR, as it also enables DH customers to participate in DR program despite flat tariff. Additionally, utilizing the deep borehole together with a small thermal storage can attain a carbon-free DH system. Finally, the inherent flexibility of the DH system has the potential to integrate a greater share of RESs, which enables utilizing the excess renewable generation in other sub-sectors, such as partial electrification of the DH and transport sub-sectors.

The developed frameworks can be utilized by load aggregators, system operators, and policymakers to get a deep insight into the DR opportunities, the advantages of cross-sectoral integration for better integration of RESs to accomplish carbon-neutral energy systems as emphasized in the European Union climate strategy.