I followed a lowcarb diet for years (both as a carnivore and as a ovo-lacto vegetarian) and didn't have a problem but when I decided to go vegan, I knew I would be very limited if I went totally lowcarb. As one person mentioned here, it depends on what you consider "low" and "high". Though I'm not lowcarbing I know that grains (even whole grains) are my weakness so I keep them to a minimum (usually, no more than a serving or two a day). The rest of the time I eat veggies, fruits, legume, meat subs (I try not to go for too many processed foods like veggie burgers or sausages - I usually go for Morningstar Farms veggie "crumbe", which is about 3 gr carb and 10 gr protein for a 2/3 cup serving - tofu, of course - and I just discovered Bob's Red Mill TVP - a 1/2 cup serving is 6 carbs and a whopping 24 gr protein

), and some good fats (olive oil, mainly). I am usually able to get to about 100-120 carbs a day (which by Atkins and other lowcarb diet standards, is pretty high, but by ADA guidelines, is more than half of what the recommended daily allowance is) and 60-70 gr protein. One day I managed to average 80 gr protein but don't ask me how I did it!
So, yes, there is such a thing as lowcarb/high protein vegan, if you loosen your definition of lowcarb (i.e., not the 20-50 gr carb/day you usually see with most of the standard lowcarb plans)
Tam