Transferring Website to Wordpress, will it effect my SEO?

Transferring Website to Wordpress, will it effect my SEO?

I have a portfolio website written in HTML (php) and I would like to replace it with WordPress CMS. The idea is to remove everything from the root, do a fresh install of WordPress, then do my best to copy all the articles, images and information onto the new WordPress theme mimicking the existing structure. I would just like to find out how much this will effect my SEO (in the long term). I expect I would drop ranking for a while but is it likely Google will accept the big update and understand that the content is the same? The reason I am moving to WordPress is because I have handful of new sites using WordPress which have saved me loads of time avoiding hand coding, I feel that I can update more regularly if I switch my old site to WordPress too. I only have one or two articles which are pulling in traffic at the moment and those are the main pieces of content I hope to preserve in regards to SEO.