As /u/iorgfeflkd mentioned, we've always been 30 *fully funded* years away from fusion power. Without a massive shift in focus towards fusion, there won't be any grid-scale fusion power plants out there for a long time, but that's not to say we aren't making progress. [Here](https://i.imgur.com/BN0pz.png
) you can see that the triple product (the product of density, temperature, and confinement time) of various experiments has been steadily increasing over the years, approaching the target for a potential commercial reactor.
Fortunately there are several large-scale magnetic fusion projects that are currently underway, off the top of my head the most important are ITER, W7-X, and EAST. Ultimately what any of them are trying to do is increase that triple product, which essentially means producing enough energy that it can be harnessed and sold, and build a reactor that's resilient enough to operate with a high capacity factor for an extended period of time.
Breakthroughs on the triple point are a matter of incremental progress. We know enough at this point that a theoretical reactor (like DEMO) would be able to produce usable amounts of energy, it's a matter of getting the funding and then actually designing and building a reactor that is larger and has around 10 times the output of ITER. It's nothing to sneeze at, but it's not as if there are serious breakthroughs that need to be made on the theoretical end for this to be possible.
The other factor is materials. Currently, test reactors operate at much lower energies and for much shorter times than a power plant reactor would need to operate. This brings the issue of erosion. A burning plasma outputs a lot of heat and radiation, and the interior of the reactor needs to be able to withstand that for long enough that you're not spending 10% of the time making energy and 90% of the time replacing components. Different experiments use different combinations of materials for their walls, and there are facilities designed to test samples of materials inside a fusion environment. Some materials are just extremely durable, like Tungsten, while others are carefully designed or have coatings applied to minimize erosion.
There are countless subfields related to fusion research, and a lot of people are making steps towards commercially viable fusion power, but it will be some time before it's a reality if there isn't a concerted effort worldwide to make it happen.
The proviso of that statement is that if we want it in 30 years, we'll have to pay for it now, and funding has been massively cut since about the 70s. [The problem with fusion power](http://klotza.blogspot.com/2016/08/whats-deal-with-fusion-power.html
) is that it requires an *extremely* large investment to get an initial prototype working, and that hasn't been put forward. The closest thing is the ITER facility that is being built in France, which will be big enough to generate more power than it consumes (although it's not designed to make electricity), but not big enough that the power can be sold for a reasonable price to recoup costs. A lot of the other research going on has to do with reducing some of this required overhead, e.g. improving magnetic containment technology so the magnets don't have to be quite so big and use so much power. There are also other experiments like the National Ignition Facility that try to look at it on a smaller scale by shooting giant lasers at tiny fuel pellets.