If Scotland is to successfully integrate a variety of renewable energy sources - including wind, tidal, wave and others – into the electricity power system then a new system of managing the variability of those sources is going to be required.
Managing a variable renewable energy production
Conventional coal or gas fired and nuclear power stations generate extremely stable power supplies. They provide electricity to the grid using specific voltages and frequencies using agreed standards and it is rare for them to deviate from these. So, we can all be quite confident that everything we connect to the grid via our domestic or industrial supplies will work properly.
However, the advent of renewable energy targets to combat climate change and the rapid expanding deployment of variable output sources of renewable energy changes all that. By its very nature the output from wind energy systems in particular varies in accordance with the wind speed. At an extreme, no wind means no power but equally too much wind might mean wind turbines having to be shut down for safety reasons. Tidal energy systems will be more predictable but in many ways, wave energy output will be similar to wind in that it will vary with wave height.
Similarly, any growth in solar energy is likely to lead to a fluctuation in output although biomass fired generators will not.
While the fluctuations in output from large scale wind and wave will be difficult enough to deal with there is now also the prospect of increasing levels of very small scale domestic or small industrial generation. Consumers are being encouraged to connect technologies such as micro-wind turbines, solar panels, micro combined heat and power systems, small scale hydro and other technologies to the grid enabling them to sell back any excess electricity they generate.
Managing changing patterns of demand
On the demand side it is likely that the use of new hydrocarbon fuel replacement technology such as air or ground source heat pumps for domestic heating will increase and as the roll out of electric vehicles also gathers pace then together these could create a major increase in overall electricity demand.
There is also a strong possibility that these new technologies could cause sudden and very large surges in demand when – for example - consumers all arrive home at roughly the same time and plug in their electric vehicles to recharge them and they all switch on their heat pumps to warm their houses.
New control technologies
Existing transmission and distribution networks are not designed to be capable of managing these demand surges but new control technologies could help smooth out these demand profiles and better manage changes in demand to prevent network capabilities being exceeded and therefore damaged.
These new control technologies will form part of the so called “Smart Grid” which is essentially an intelligent network capable of monitoring itself and making decisions on how to maintain power quality and stability. In order to achieve that it will require new monitoring technologies so that almost everything connected to the grid will be able to tell the control system how much energy it is consuming or indeed generating.
The intention is that this should lead to a situation where both domestic and industrial equipment operates on a “plug and play” basis where the network adjusts itself automatically to take account of a new demand or a new supply source.
Active network management
This form of “Active Network Management” can be described as the “pre-emptive operation of a system to keep networks operating within their design parameters” and will involve the remote operation of devices or complete systems to change network configurations in order to manage constraints. Similarly flexible generation could be
dynamically controlled via automated systems that manage parameters such as voltage utilising transformer tap changers.
In order to be able achieve all this in real time will require new distributed and intelligence control algorithms coupled with fast and reliable communications networks specifically designed to operate with the large range of equipment involved.
Similarly, the software control system that will run such a network will need to be extremely reliable and also flexible and scalable to enable new hardware components to be added without incident.
Scottish universities have a strong and successful background in: power systems; power systems modelling, simulation and analysis; active network management and renewable energy integration; power electronics; machines; high voltage technologies; protection and control; and, monitoring and diagnostics.
Scotland is therefore well placed to help develop this new generation of smart, power system technologies and so contribute strongly to the reduction in carbon emissions, improve energy efficiency and maintain a secure but diverse power supply.