Developed an extensive knowledge...???

[SunMoon]

I developed an extensive knowledge in Project Management...

OR

I developed extensive knowledge in Project Management...

OR can I say something like this:

I extensively developed my knowledge in Project Management working with tight rules and strong formal policies within a company where standards, rules and policies are a must.

???

[bhaisahab]

I have extensively developed my knowledge in Project Management, working with tight rules and strong formal policies within a company where standards, rules and clear policies are a must.

This is my suggestion.

[Tdol]

How about 'a thorough grounding in Proghject Management'?