50 Hz - Wie wir einen Blackout vermeiden

One frequency An interconnected European network In balance 50 Hertz - How we avoid

blackout

s. 50 Hertz, the measure of all things. A number that has more importance in our lives than we think. Because this number defines the pulse of a cornerstone of the modern world: energy. To be more precise, electric current. Throughout Europe, the electric current pulses with the same frequency: 50 Hertz. Failure to maintain this frequency could have dramatic consequences. Blackout. But what are the chances of a

blackout

? And what's the problem with 50 Hertz? To answer these questions, we need to travel back in time. The question arose: what is the ideal frequency for electricity?

High frequencies turned out to be an obstacle in the construction of rotating electrical machines used at that time as motors, generators and converters. Because the higher the frequency, the faster the motors spin. This, in turn, causes increased wear and tear. With 25 Hertz we tried to keep the frequency as low as possible. However, if the frequency is too low, the light flashes with alternating current. Imagine alternating current as a sine wave. It constantly changes direction between positive and negative. This means that the current averages zero over time. As a result, a light bulb goes out for a short period.

For the human eye to perceive calm and stable light, the alternating current must change direction at least 5,000 times per minute. This corresponds to a frequency of approximately 42 Hertz. Therefore, 50 Hertz is an ideal value, as it keeps the voltage drop within limits for transmission lines and the frequency is suitable for the operation of motors and incandescent lamps. 50 Hertz is a kind of speed. It is a rotating generator that produces these 50 Hertz. And it rotates at a certain speed, which results in exactly 50 Hertz. A magnet is attached to the rotor drive shaft. The electrical connections are located on the coils.

When the magnetic field moves through a coil, a current flow is generated. The positive pole causes the current to flow away from the generator. The negative pole causes current to move towards the generator. This change in the direction of current is called alternating current. The rotation speed of the generator determines the frequency. Practically from the generator to the consumer, all motors and all devices are practically designed for 50 Hertz. If the frequency of 50 Hertz in the network is not correct, then at home the motor of the router or the ventilation device no longer rotates at that speed.

In the electrical network we refer to 50 Hertz as the network frequency, which represents the measure of stability that must be maintained in any case. In practice, however, the frequency is not completely stable, but fluctuates slightly up or down, depending on the amount of power currently needed. The limits of 49.8 hertz must not be exceeded or exceed 50.2 hertz. The electrical grid has no storage capacity, meaning generation must always match consumption wherever it occurs. And that is why we can say that 50 Hertz is the measure of all things. Hertz fluctuates depending on whether there is too much power on the grid due to overproduction or too little power on the grid due to overconsumption and so generation adjusts to match this 50 Hertz.

Then something happens on the grid similar to riding a bike. We travel at a certain speed on flat terrain and then the road begins to incline. If we pedal with the same force, we reduce speed. If we want to maintain 50 Hertz or maintain speed, we have to pedal faster. And that's what happens with generators. If we do not provide more power to the generator, it will slow down. But we want to maintain those 50 Hertz. That is why we provide more energy to the generator, in our case, from illwerke vkw, it is water. For example, if electricity demand, or load, increases unexpectedly, there is a slight slowdown of the generators and therefore a decrease in the grid frequency.

This is where the so-called operating reserve comes into play, which compensates for fluctuations in the industrial frequency. However, if the power generation is higher or the load is lower than expected, the grid frequency increases. The rotating mass of all the generators in our electrical grid causes a certain inertia in the system. In the short term, this alone leads to frequency stability. The balance between generation and consumption is a requirement for an electrical network to function. Unlike other goods, electricity has no delivery time, but now electricity is everywhere. This concept can be represented like this: when electricity is generated in Montafon, which is now needed in Lisbon, it is like a tube full of balls from here to Lisbon.

And when we put a ball into this tube, naturally, at the same time a ball falls from the tube in Lisbon. Electricity is everywhere now. However, since the electrical grid is not a storage system and a balance must be maintained, there are systems that balance and correct the frequency continuously. These are called operating reserves and are divided into three parts. For example, if the grid frequency drops, the primary control is activated first. It is the fastest response and should be available within 30 seconds. Secondary control is used to balance generation and consumption and must deliver full power within five minutes.

If the secondary control reaches its limits, the tertiary control provides additional power in the form of a constant band. Like our central nervous system, the widely branched electrical grid extends throughout our community of states. All of Europe works at the same pace and all of Europe feels that the switch is turned on here in Montafon or in Vorarlberg. And whether they like it or not, everyone contributes to maintaining this frequency. The rotating mass of all of Europe works together to maintain this 50 hertz and the generators of all of Europe also work together. It is not a local issue, it is pan-European.

Therefore, the electricity grid in Europe is built as an interconnected network. It has the advantage of being a very stable system due to its size. One of the tasks of transmission network managers is to maintain this frequency, specifically at 50 hertz. There is a defined band of plus or minus 200 millihertz, which serves as the target band. To maintain this frequency, system services are required. Power plants are relevant to this as they can provide these services. For example, illwerke vkw is perfectly prepared to offer these system services with its pumped storage power plants. The operating principle of pumped storage power plants is simple but convincing.

It consists of an upper and a lower tank. In the middle is the generator with a turbine and a pump. If you want to generate electricity, you let water flow up and down through the turbine. On the contrary, we may have surplus energy on the grid from alternative energy sources. In this case, we can draw power from the grid and use our generators to pump the water back to the upper reservoirs. There is a range in which machines operate. And depending on the signal, it can provide power quickly or not provide power at all. That's why you can also provide primary energy immediately.

Not in half a minute. We can do it instantly. In the past, you turned on two machines and waited for a call if a third was needed. Due to current demands, power plants must operate much more flexibly than 20 years ago. Interestingly, at the beginning of my career I did my apprenticeship at Lünerseewerk. And in Lünerseewerk there are five machines: turbine-pump. So they can do both, turbine and pump. And at that time I allowed myself to ask myself the question: What if we pumped and turbined at the same time? Of course, for me as a trainee, it was almost dangerous to ask that question, because it seemed impossible.

Today it is completely normal. Therefore, back then the machines were only designed to run on turbines or to pump. But all on the same axis. And today, thanks to experiments, simulations, and new calculations, it is possible to turbine and pump simultaneously with the same machine. The pressures are controllable. That was the big problem: whether the pressures could be controlled. But you can. And controls and regulations have also improved. And now we can pump and turbine simultaneously. And so, we can deliver more or absorb more energy in seconds. These are our control pumps. And we were certainly leaders in Europe in the use of such technologies.

When we consider our fleet of primary control machinery we can say that at illwerke vkw we have some of the best and fastest machines on the European market. For example, today illwerke vkw is the main regulator for the entire German market. This is due to historical reasons. Our ancestors were true pioneers. From the beginning they made sure to build fast power plants. At that time, control energy was unknown. Energy control has only become relevant in the last ten or twenty years. We are increasingly moving towards renewable energies. Independence from fossil fuels is an important goal. Although renewable energy is an inevitable consequence, it presents challenges.

To deal with low or high network load, forecasts are made preventively. This way, power plant operators know how much electricity to generate based on demand forecasts. We know every quarter of an hour of the next day what the cargo flow will most likely be like. That's one point: good change planning. The challenge of new energies lies in the fact that the wind does not always blow or the sun does not always shine when it should. And that means controlling energy becomes even more important. Of course, our networks are increasingly overloaded. As fluctuating sources, they are increasing.

That is, alternative energies. Due to climate-related challenges, electricity production is not equally constant. During periods of low sunlight, electricity production is lower. Many hours of sunlight cause excess electrical energy. Surplus electricity cannot currently be stored. In my opinion, in terms of renewable energy it is clear that as a society we have no chance. In the medium term we must adapt and move to renewable energies. It will cost a lot of money. It will raise technical problems. But these technical problems can be solved. Like almost all technical problems so far. Of course, there are also attempts to integrate new energies into this regulation.

Attempts are being made to use battery storage. Efforts are being made to provide secondary control with wind power. In my opinion, there should be a combination of the currently developed storage options. But large-scale storage is currently only possible with pumped storage power plants. In the future, as we build more alternative energy facilities, more flexible hydropower plants will continue to be needed. This is where large pumped storage power plants, such as the planned Lünerseewerk 2 project, play an important role. Lünerseewerk 2 is a very large project because it represents almost half of the current capacity. Almost half with 1200 megawatts.

Currently we have 2400. 1200 is not just almost, it is half. It is, of course, a gigantic power plant. But it is very well located. It is connected to the largest reservoir we have. The Lünersee has a water capacity of 74 million cubic meters. And of course, the proximity to the Bürs substation would also mean that no additional lines would need to be built directly for the connection. But I think, especially because of the controllability, this will be even more important. When the base load power plants lose their boost masses, we will be grateful if we can provide some boost mass here.

To maintain stability. Numerous systems guarantee daily stability and a reliable power supply. It takes a series of unfortunate events to cause a widespread blackout. Although it is unlikely, let's imagine such a scenario. A blackout is defined as a large-scale power outage that can affect multiple cities, regions, a country, or even multiple countries. Day 16 of a heat wave throughout Europe. Humans and nature suffer from extreme conditions. The rivers flow with little water. As a result, hydroelectric generation has been cut in half. Thermal power plants, which depend on river water for cooling, must reduce their production. The remaining power plants in the south are being reinforced.

Meanwhile, planned maintenance work is being carried out on the relevant 380 kV lines. Several power plants are undergoing scheduled overhauls. A strong injection of wind power in the north is causing additional stress on the lines. The situation is tense. Forest fires are ravaging parts of Europe and have already destroyed a linemain electrical. This creates a critical load distribution on the power grid. Efforts are being made to redistribute energy. Power plants are connected at certain points and pumps are activated at other locations. Due to the enormous voltage, the frequency drops below 49.8 Hertz. The system protection plan is activated.

The generators are started and the pump is stopped. Due to overload, additional lines fail. Power plant and grid operators are on red alert. Consumers are offline to provide relief. All measures are being taken to avoid a blackout. But the cascade is inevitable. A chain of events leads to the frequency falling below 47.5 Hertz. This triggers an automatic protective shutdown of all power plants. It turns dark. Blackout. Power plant and grid operators illwerke vkw and VÜN are working at full capacity. A crisis management team made up of representatives obtains an initial overview of the situation and coordinates all operations.

Emergency power supply to power plants has been started automatically, thus ensuring self-sufficiency. Vorarlberg is now managed as an island. This means that we are temporarily isolated from the European electricity grid. The main control center in Bregenz and the dispatch center in Rodund agree on a strategy and are in constant communication with each other. All substations are put in the open state and are therefore disconnected from the power grid. The blackout itself is characterized by a very rapid onset where neither automation nor humans can react in time. And as soon as we realize: Well, and we in Vorarlberg realize: it is a blackout.

Then the automatic processes start running. Now it gets exciting in terms of communication. Thus, crisis communication is immediately initiated and crisis teams are alerted. We have a communication system to raise the alarm quickly. All substations are staffed, operational centers are informed, all to establish a solid foundation of communication. And we have exactly one employee on our side and exactly one employee in the dispatch center who are talking on the phone and these two rebuild the network. The electrical grid is now divided into smaller sectors, to facilitate the restoration and reintegration of electrical energy. Immediate restoration of power supply in Vorarlberg could lead to another system collapse due to excessive load.

Of course, the whole process is very delicate. When I want to rebuild a network, I can only connect 5% of what is rotating now. So if I have a 100 MW generator rotating, I can only connect 5 MW. The entire process must be divided into small parts. And then one of our black start capable power plants activates. illwerke vkw power plants have black start capability which sets them apart. And the screen starts to light up again. It can be seen that in a small area of ​​Montafon (Vorarlberg) there is tension again. This means that these power plants are capable of completely restoring power supply autonomously.

Large thermal plants, such as nuclear or coal plants, lack this capacity. Having black start capability means generating power independently, without external supply. Thus, the power plant itself has enough energy in the form of batteries or emergency generators or home generators to start up independently and generate power. Now power plants are gradually restarting. Following the 5% rule, new consumers are constantly connected. You can only consume as much as you generate. And when specific consumers are connected, it must be guaranteed that the machines can produce that energy. We will have approximately 500 MW of rotating mass initially connected to the grid.

Then we will see the frequency drop. Normally we have 50 Hz and when we connect a substation, the frequency drops and stabilizes. The load is gradually increased until all homes have electricity again. If it is simply an imbalance, Vorarlberg will have electricity again within a few hours. If the infrastructure no longer exists, it may take days or even weeks for the last person to have power again. Technically we can offer electricity again very quickly. Whether we can distribute it is another story. How long it takes is a difficult question because the fundamental question is: Why did the blackout occur?

And really, we don't know when it will happen. We assume and hope, of course, that all systems are working. We have very good systems and redundant systems. That means if one system fails, we have another and an emergency system. And if we assume that the systems are working perfectly and that nothing has been damaged, within 12 to 24 hours we should have power supply to Vorarlberg. Because in Vorarlberg we have a fleet of top-class power plants and a very powerful network, not forgetting the dedicated employees who will do everything to ensure fast electricity supply. These functions that are needed have been implemented by us from the beginning, adapted and constantly improved.

We employ people to be the best for our region, Vorarlberg. The installations are not only designed accordingly, but are also tested. Every installation is tested annually, every machine is tested annually: Will it be able to handle black booting? Am I ready when I start? This means that people working together must be trained, and the training is done on simulators. We practice it ourselves with our real machines. For me personally, a power outage means that I try to contribute as quickly as possible to restoring a secure power supply. In recent times we have experienced heat waves followed by heavy rain.

Despite these elemental stresses, the grid frequency could always remain stable. This shows us how unlikely a blackout really is. I'm not afraid of a blackout. I am also not prepared in advance, I have no backup power. I am confident that what we have always done until now will work.