Why do grid operator have to pay customer to use up the excess electricity to avoid the potential blackout. But can’t they ground it into the literal ground/earth?
In: 131
Electricity producers can’t turn the supply up and down linearly. They can bring a generator online or shut one down, but there’s no in-between. Generators, or more specifically, alternators create voltage at a fixed frequency and amplitude. It’s fed directly to the grid – not regulated to DC and back to AC.
Couple of reasons for this, main one is if you ground a live circuit to earth you induce earth fault currents which will cause nearby generation to feed the “fault”. This would then lead to cascade of protection relay events which would cause substations to power down and lead to a blackout.
Can someone eli5 the question?
They can’t “ground it into the earth” because that would cause all sorts of issues. The thing they do most often is designate certain plants to “follow” the load. Most plants these days have high-tech exciter equipment that magnetizes the generator field (the rotating part of an AC generator) in a precise manner. They can program the exciter to put out a certain amount of voltage which corresponds to a certain amount of power out of the generator. If the power out is decreased, the amount of torque needed to drive the generator goes down so the throttle can close down, saving fuel/steam.
During all this, the RPMs the generator turns will not change. The generator is synched to the “infinite bus,” which is essentially the grid as a whole. One generator or even a whole plant cannot significantly change the frequency of the whole system, so all the plant can do is change the amount of power it’s pumping into the system.
[deleted]
You cannot ground it like you say, you need expensive resistance equipment to do that. So ELI5 – it’s just cheaper longer term to pay people to use more than to build the equipment to absorb the excess.
Grid always has to be in balance (110v-60Hz or 220v-50Hz), otherwise brownouts or blackouts will occur. There are many safeguards to prevent under and over production of electricity on plant level and managed by grid. When there is an unexpected drop in demand grid operator can say one or more plants to cut production but grid operator has to pay the plant for this to happen. They will pay plant to not produce. It is not being greedy on plant side since it takes about eight hours for natural gas plant to completely stop and it will continue to produce in the process also cost of starting a plant again is kinda too high. I had optimized a code that optimizes power plant and let me tell you it is crazy, an hourly production plan for the next 20 years crazy.
Now which plants do receive this kind of orders? There is a market for this and they bid how much they can produce extra and how much they can cut, and for how much money. Electricity is a trade-able entity so every one is trying to cut the losses. If cost of you using is lower than plant bids, just use it man, it means lower electricity bill on average for everyone.
Disclosure: my company develops systems for electricity producers and traders. It is infinitely complex and fun system, so my information is not 100%, but that should cover it
Latest Answers