Key Concepts in the Electrical Grid

The electrical grid is changing rapidly. The energy transition and electrification of society are placing new demands on our electrical systems. To understand both challenges and opportunities, we need to be familiar with fundamental concepts. This article presents the central terms that describe the electrical grid's structure, function and future development.

The National Grid (220-400 kV) is the highest level of the electrical grid. It functions as a national backbone that transports large amounts of electricity over long distances. Svenska kraftnät owns and manages the national grid, which also connects Sweden with neighbouring countries' electrical systems.

The Regional Grid (40-130 kV) links the national grid and local grid. Larger energy companies typically own these networks, which cover several municipalities or regions. The regional grids also supply larger industries with electricity.

The Local Grid (0.4-20 kV), also called the distribution network, branches through cities and rural areas. This is the final link in the chain that delivers electricity to smaller industries, businesses and households.

These three levels form the basis for electricity's path from production to usage – and face new requirements as usage patterns change.

Substations are critical junctions in the electrical grid where electrical voltage is converted between different levels. These facilities vary in size from large national grid stations to smaller regional grid stations. Beyond voltage conversion, they have several functions such as network monitoring and system protection.

Modern substations are increasingly equipped with digital sensors. These monitor critical components and enable condition-based maintenance, which extends equipment lifespan and reduces the risk of outages and environmentally hazardous emissions.

Distribution substations are smaller substations in the local grid. They convert medium voltage (10-20 kV) to low voltage (400 V) that end users can utilise.

Lines and cables transport electricity through the grid:

• Overhead lines are more common at higher voltage levels and are cost-effective over long distances
• Underground cables dominate in densely populated areas and are less sensitive to weather

The infrastructure is changing with increased digitalisation and new usage patterns – something that affects both operation and maintenance.

The energy transition is driving the development of the electrical grid towards new solutions:

Smart Grid integrates digital technology into the electrical grid for better control of electricity flows. This increases efficiency, reduces outages and provides real-time information about electricity usage, enabling more active choices for both network owners and customers.

Capacity challenges arise when more electric vehicles and industries connect. The demand for electricity is increasing dramatically and many regions already have limitations that hinder growth. The electrical grid must therefore be reinforced or used more intelligently.

Flexibility becomes a key tool for adapting consumption and production to available capacity. It involves shifting electricity consumption from peak load times to quieter periods and controlling production according to need.

Microgeneration from sources such as solar panels turns more people into both producers and consumers. This changes the electrical grid from a unidirectional to a multidirectional flow, creating opportunities for local energy sharing.

Energy storage becomes crucial in a system with more variable electricity production. Batteries can store surplus electricity for later use, and large-scale storage can deliver important system services such as frequency regulation.

Digitalisation and automation are transforming the entire electrical system. IoT sensors and real-time monitoring collect data from all parts of the grid. Artificial intelligence analyses this data to optimise operations and predict potential faults.

Automation in substations provides remote control and faster fault management, reducing outage times. Advanced algorithms balance the load to create a more efficient and robust electrical grid.

At the same time, increased connectivity places higher demands on cybersecurity. A more digital electrical grid is also more vulnerable to intrusion, sabotage and manipulation. Protection of critical infrastructure therefore becomes a central part of the grid's future development – both technically and regulatorily.

The electrical grid is facing one of its biggest changes to date. Increased electrification, more local production, digitalisation and new load patterns are changing how electricity is produced, transported and used. With a good understanding of the grid's basic concepts, it becomes easier to follow and influence this development.