Research related to intelligent control in smart grids within the Dynamics, Control and Vehicle Research Group comprises a set of interconnected research themes, as can be seen in Figure 1.

Theme 1 - Controllability and realiability assessment

The main driver for this theme is increasing renewable energy capacity through improving electricity grid reliability and controllability, hence reducing the impacts of the uncertainty of renewables. This will be done by means of development of algorithms for evaluation and improvement of metrics such as Loss Of Load Expectation (LOLE), Energy Not Supplied (ENS), and controllability metrics. Tools will be developed for network probabilistic reliability evaluation (e.g. Monte Carlo simulations) and controllability assessment (e.g. Kalman’s controllability criterion: rank(C) = N). The probabilistic tool will then be extended to include energy constrained resources (e.g. storage), which are modelled differently than other resources.

Theme 2 - Multiple Energy Carriers / Energy Hubs

This theme is about managing the interactions between AC and DC electricity, gas, heat and other networks. It is especially applicable to urban microgrids, where more than one utilities supply power with different energy carriers. The Energy Hubs approach is about finding the optimal combination of energy inputs for a given demand, with e.g. non-linear optimisation:

 

 

 

Work is being undertaken towards combining intelligent control with multiple energy carrier optimisation. The reliability and controllability algorithms developed in the previous theme will also be expanded to consider combined energy networks.

 

Theme 3 - Distributed energy resources (DER) and energy storage (ES)

Algorithms are being developed for facilitating coordinated response of DER / ES during emergencies (e.g. blackouts), rather than leaving them to respond randomly (e.g. disconnect), aggravating the problem. There is also the prospect of linking flexible DER (e.g. controllable distributed generators, electric vehicles, flexible loads) with intermittent renewables, “filling the gaps”, such as absorbing excess wind energy or covering for gaps in sunlight. Literature shows that DER have the potential to support maximisation of renewable energy penetration, through mitigation of uncertainty.

Theme 4 - Intelligent controllers and power electronics

The previous themes are brought together by intelligent control, which essentially comprises distributed local controllers (agents) installed on the resources (e.g. on a generator). Resource aggregation and coordination through those controllers can lead to thousands of DER behaving like a single resource, i.e. a power plant. This is referred to as a Virtual Power Plant (VPP) and can also be used for grid integration of electric vehicles (see EU FP7 MERGE project). The controllability & reliability algorithms developed in the previous themes will be implemented on intelligent controllers, for improving energy system operation. These controllers will be able to interact with the power electronics of the energy resources, resulting in enhanced and more co-ordinated control of their interaction with the electricity grid and improved flexibility of their interconnection. This may also lead to individual or aggregated provision of ancillary services by DER.

Theme 5 - Smart Grids / Smart Cities

The previous themes contribute to the development of Smart Grids and Smart Cities. The main purpose of Smart Grids is to resolve the energy trilemma of low carbon / affordable / secure energy supply. The best way to do this is by enabling grid integration of renewable energy. Demand Side Management (DSM) in buildings is another possible tool. The energy trilemma is especially important in urban microgrids and planned communities. Multiple energy carrier optimisation will also play a role in the operation of future energy networks, helping towards secure operation of the whole energy system.

Sources

[1]   S. Skarvelis-Kazakos, P. Papadopoulos, I. Grau Unda, (2014) “Agent-based control of multiple energy carriers and energy hubs”, 5th IEEE PES International Conference and Exhibition on Innovative Smart Grid Technologies (ISGT Europe 2014).

[2]   S. Skarvelis-Kazakos, (2011), “Emissions of aggregated microgenerators”, PhD thesis, Cardiff University.