Logo design for a conference event

I am host of a conference event that has been taking place since 2012 and each year I need the logo revised and refreshed to accommodate the year (part of the logo) and the theme and colour. I can supply previous logos to guide the designer as well as a clear brief of what I need. This is not a complicated job as I already have an idea of the theme and colours for the next edition. I will require the finished logo in multiple formats (png, jpeg, vector etc).