Improvements in technology and growth in power electronics on the grid has brought DC back into focus. Alan Binning, regional sales manager at energy software expert, COPA-DATA UK, explains why.
In the late 1880s, Thomas Edison and Nikola Tesla began a conflict known as the war of the currents. The two inventors and industrialists battled over whether Direct Current (DC) or Alternating Current (AC) should be used to distribute electricity. Ultimately, AC’s ability to work with transformers to easily increase and reduce voltage to transmit electricity across long distances won, and has reigned supreme for more than 100 years.
As renewable energy and smart systems become a larger part of the grid, more flexibility and resilience is needed. As renewable energy generation fluctuates, demand must be met with infrastructure that enables greater control.
Direct current (DC) offers several features that make it an excellent choice to enhance the stability of the modern grid. Firstly, its greater efficiency than AC, coupled with the fact that it can be used alongside existing infrastructure, makes DC seem an excellent way to add capacity and resilience to the grid without investing in new substations and connectors.
DC could also offer a more straightforward way to facilitate smart or microgrid applications. For example, it reduces the number of conversion steps between dc sources and dc loads and eliminates the need for frequency synchronisation. Power converters introduce greater flexibility and controllability, ideal for use with energy management systems.
Distribution network operators are exploring how they can take advantage of DC’s properties to build a more flexible, sustainable energy grid.
DC in action
DC share by Western Power is an MVDC project that aims to facilitate rapid EV charging, key to the uptake of EVs. This smart DC network uses the available latent capacity across multiple distribution substations in constrained areas. The substations are connected to DC converters and high capacity DC links.
The project uses DC to optimise existing assets and minimises the impact of clusters of rapid charging points on the wider grid.
Outside the UK, a new project, TIGON, involves 15 partners from eight member states of the EU. It aims to show how DC microgrids can support the EU’s green ambitions, and improve technology readiness for the widespread use of microgrids.
Launched in September 2020, the project will set up two microgrids in Spain and France. The microgrids will incorporate solar power, energy storage systems, EV charging points and other DC loads. To achieve this, TIGON will rely on pioneering grid technologies including energy management systems, solid state transformers, and DC/DC converters.
Software for DC
If energy companies are to take advantage of the flexibility and resilience offered by DC, the ability to analyse data in real time is essential — especially when DC networks are connected to renewable power.
If DC infrastructure is to be widely used, its scalability, security, and connectivity becomes essential. Whether it is renewable power plants, energy storage systems or EV charging points being integrated to the grid, software like COPA-DATA’s zenon, can make each asset more controllable and efficient for smart grid applications.
Though the war of the currents ended with one clear winner, the demands of modern energy distribution mean there is room for AC and DC to work together. As the growing number of DC projects show, there is a real need for flexibility and controllability in the grid. What’s more, the projected increase in renewable power and EVs mean these properties will become even more in demand. DC infrastructure offers one solution to futureproof the network and create a resilient, low-carbon grid.