A controller is proposed for a medium voltage medium frequency (MVMF) AC collection grid for utility scale Photovoltaic (PV) farms. A new MVMF AC collection grid was presented in previous work. It enhanced the system modularity, increased the system efficiency and reduced the passive component sizes. The MVMF AC collection grid comprises modules of inverter and medium frequency transformer that are series connected to construct the MF-AC collection grid. An AC/AC cycloconverter is used to interface the MF-AC collection grid to the low frequency utility grid. This paper presented an easy yet robust and fast controller for the proposed MVMF AC collection grid. An 80MW PV power plant located in Eggebek/Germany is used as a design example. The proposed controller is presented in details followed by simulation and hardware results to proof the fast/robust response of the proposed controller.