Prevent users from using power pivot excel connections to a database
You can do that using LOGON TRIGGER.

something like below :

--Prevent acces from Excel
CREATE TRIGGER tr_stop_excel_users
ON ALL SERVER FOR LOGON
AS
BEGIN
IF APP_NAME() LIKE '%excel%'
 ROLLBACK
END


Refer to my answer here as it has the script to achieve it as well. You have the flexibility of customizing the script to check for Application, Users, etc and depending on what you want to allow or not, the table that governs the script can be modified.