Of the sources of electricity generation, some have inertia and others do not. Inertia is the energy accumulated in a moving body—if the motion is linear, it is expressed as the mass multiplied by the velocity squared, and if it is rotating, it is expressed as the mass and its distance from the axis of rotation squared, multiplied by the angular velocity squared. Kinetic energy. This energy dissipates over time, but instantly tends to be maintained, whether the force opposing the rotation increases or decreases. In short, if a hydraulic turbine sees the force opposing its rotation increase or decrease, its speed will immediately decrease or increase very little, due to inertia. The same will occur with a combined-cycle gas turbine.
Renewable wind energy is generated at a variable frequency—a function of the wind speed at the wind turbine blades—but to be injected into the grid, it must have a fixed frequency: 50 Hz in Europe and 60 Hz in the US. To do this, the variable-frequency electric current is converted into direct current and then re-waved at the fixed grid frequency. This is achieved using static converters in which the delivered energy is independent of the incoming energy. Consequently, they lack inertia, and grid fluctuations are not automatically compensated. In this case, and also in the case of solar panels that generate direct current, the grid is decoupled from the generator and therefore has no inertia, unlike in the case of hydraulic or gas turbines. Without inertia, frequency variation does not self-regulate, and the system protects itself by decoupling the generator from the grid if the predefined frequency tolerance is exceeded.
The connection of different types of generators to the grid is based on the energy price at any given time, defined by supply and demand. If the price is low, only generators generating at a low price are connected; if the price rises due to increased demand, more generators with higher generation prices are connected. However, there is no monitoring to ensure that at any given time there is a mix of generators connected with inertia that stabilizes the grid. This monitoring could be exercised without having much impact on the profits of the companies. utilities (companies that use public service infrastructure) that generate energy.
Today, computing power is almost unlimited. The behavior of the national grid can be simulated under different generation and consumption conditions. It would be useful to review this to prevent, through phased protection, widespread blackouts like last Monday.
There have been comments about the usefulness of having batteries connected to the grid or the possibility of storing energy. This would be an advantage, but this is a separate issue from protecting the grid from frequency or instantaneous voltage instability, which is what caused the system to fail. The system protects itself by disconnecting if certain tolerances are exceeded, causing a blackout, which can be massive if the phenomenon spreads: one disconnection causes others.
What happened on Monday, April 28 in Spain has also happened in other states for similar reasons. The most massive blackouts occurred in India and Pakistan (2012), where hundreds of millions of users lost power for days, and the longest-lasting blackouts occurred in the northeastern United States (2003), where power restoration took weeks.
The reaction of Red Eléctrica, responsible for energy distribution, was swift, but this must be prevented from happening again. This can be done by simulating its behavior in order to change the configuration of production units and, consequently, avoiding massive blackouts like the one experienced a few days ago. The criticism that can be leveled at the national energy security plan, which is 10 years old and should have been revised five years ago, is that a local frequency failure spreads across the entire grid to 15 GW, 60% of the demand at that time. Local protections must protect the overall grid and contain the initial local failure.
The situation led to all kinds of speculation regarding the authorities' reaction. In today's society, communication is as important as the actual event itself. When an incident occurs whose causes are unknown, speculation should be avoided, as it can generate further fear and anxiety among the population. When this happens, it is useless to propose solutions before having a detailed understanding of the problem, but it is possible to recommend measures to the public to avoid further damage and inconvenience, such as not using electric transport, trains, subways, and elevators, avoiding unnecessary travel, etc. Not enough was done, possibly due to a lack of experience with these types of incidents, but there is little doubt that the behavior of the public has been exemplary. We are a civilized people, which has reduced the effects of the incident.
Grid sectioning on interconnected islands has advantages for avoiding massive blackouts, and it would be advisable to move to a possible connection from the Iberian grid to the European grid: from the current 3% to 10%, this would help prevent them. In short, we simulate the incident by calculation, test alternative generation solutions based on predetermined consumption, verify the impact of the incident, and redesign the system configuration to minimize its effects. If we identify incidents, inherently weak configurations can be avoided, but they must be regulated instead of leaving them to the randomness of different generators' grid connections based on price.
Nothing too serious has happened, but the remedy is to take measures to prevent a repeat. There's no need to do more... or less.
