The bulk and long distance power transmission with power cable is impossible in utility ac frequency. The authors proposed the Low Frequency AC (LFAC) cable transmission to meet with that requirement. A cycloconverter can be applied to convert from utility ac frequency to low frequency for LFAC system. However, the output of the cycloconverter presents discontinuous current conduction because of the capacitive characteristics of the cable transmission line. This paper proposes the novel cycloconverter control system, which enables stable operation of the non-circulating current control to the capacitive output circuit, and proposes the three-phase output balancing control. The power flow control of the LFAC system by the cycloconverter is also confirmed through computer simulations.