I was removed from all groups before, when I changed my number. Will the same happen if I change my phone? This time, I have the same number but a different phone.
You retain your groups if you have the same number.
Off-topic, you may also want to check the official documentation on how to back-up and restore your chat history to the new phone.
Just backup your chat Whatsapp-> Settings-> Chat settings-> Backup conversations.
This will backup your chats to a database on your whatsapp folder of your SD card.
Copy the folder to your new phone and just install whatsapp and activate your account from your number. Restore old chats when asked. Voila :-)