On June 22 this year, the Polish power system was close to a widespread blackout under fairly normal load conditions.1
The are many lessons taught, one being that blackouts do not necessarily happen at peak load, although this is the by far most studied cases. On the contrary most major blackouts that we have seen globally have not been associated with peak load. The reason is that the power system is normally adapted to the load situation and in this case significant production resources were taken out for maintenance thus reducing the reserve capacity.
Another learning is the significance of interconnections with neighboring countries. This was one of the key factors that eventually saved the system. The report states:
"In a rush, the Polish transmission system operator (TSO) PSE had to import around 3,000 Megawatt from Sweden, Germany, the Czech Republic, Slovakia, and Lithuania"
Of importance is that Poland has HVDC interconnections with Sweden and Lithuania and the HVDC connections is emergency situations can serve as “virtual generators” forcing power to Poland irrespective of the voltage situation on both sides of the border.
Finally, the event is an example that renewable generation, in this case solar power was contributing with 640 MW in this critical situation.
So, what can we expect with increasing levels of renewable production in the system? It is well known that a 100% renewable power system will require solutions such as:
- - Increased interconnection capacity
- - Increased storage capacity
- - Increased demand response
- - Increased sector coupling between increasingly electrified heating and transport sectors that offers new possibilities e.g. to share storage
- - More decentralized solutions for production, storage, and variable loads
- - New business models to manage the redefined system
All these modifications of the power system are often described by opponents to the changes as “weaknesses” in a renewable energy system. What they totally have misunderstood is that the new system will by far be more resilient than the system we have today. One example is that experience gained from installing battery systems in Australia and UK is that the battery systems are far more efficient to generate system services such as frequency regulation largely because they are reacting much faster. In the example from Poland it is also brought up that old generators are kept as “emergency reserves” when frequent examples today show that battery systems are a competitive solution that can provide also other services than emergency power.
In summary, it is a myth that a system based on large scale generators will provide the most resilient power system. And it is also a myth that the main challenge for the power system is most vulnerable during peak load. A modern power system with renewable generation, more interconnections, more storage, more sector coupling between power, transport and heating, more demand control and new business models with deliver a cleaner, cheaper and more resilient power system.