This project uses control engineering and computer science techniques (primarily formal methods) to investigate the use of electric vehicles as tools for frequency regulation in a smart grid. If utilised properly, frequency regulation from the supply end of the grid will not be as necessary, which reduces costs and is more energy efficient. If electric vehicles can provide large amounts of control on the frequency, then more renewable energy can be integrated in the power grid, which is a desired task due to the large uncertainty in the generation of this renewable energy.
In this project we take advantage of the fast response of electric vehicles and use them to aid frequency control of the power grid. If there is an issue with power generation, electric vehicles can be told to stop charging, reduce charging or potentially even discharge energy back into the grid in order to return the frequency back to a stable value in a short amount of time.
To implement this approach, there are a number of challenges that need to be addressed. These challenges include finding a fleet of electric vehicles willing to participate in such a program, respecting considerations of the users and their requirements to encourage participation, and the costs associated with the reduction in lifetime of the vehicle batteries due to charging/discharging requests from the grid.
There is a conflict between a fully responsive fleet of electric vehicles that take part in the programme and having a non-disruptive programme so that the users are willing to participate. This project aims to deal with this conflict by creating a formal specification for the grid and its frequency requirements and a formal specification for the users and their requirements (this could be many individual specifications). A mathematical model can then be formed with the intent of fulfilling specifications of both sides and measuring the impact of such a model using computer simulations.
The grid specification would include requirements to prevent the frequency to exceed or drop below certain levels. The impact of this being that appliances are designed for a certain frequency and receiving an unexpected frequency may damage them. Another issue is that if demand massively exceeds supply there will not be enough energy to provide to all the loads. This will lead to power cuts and load shedding. The main goal of having user specifications is to encourage user participation. The specifications would include information such as a minimum charge the user would request that their car should have in case of an emergency (e.g. rush to hospital for pregnancy, rush to the shops for missing ingredient, etc.) and a time that the user wishes the car to be back at full charge (e.g., 8.30am the next morning for work). The worst-case scenario for a user is that they require the use of their vehicle to find that it has been used for frequency control and is now out of action, and that will have repercussions for the user such as needing to find alternative transport in an emergency or being delayed as the vehicle charges which leads to tardiness at work. An unhappy user will not wish to participate in frequency control.
Another contribution of demand side frequency control using electric vehicles is that more renewable energy can be used in the grid which has benefits in tackling climate change and is a more sustainable resource unlike coal or gas which may one day run out.