This paper presents a control mechanism on high voltage direct current (HVDC) transmission line for frequency/voltage regulation, fault ride through (FRT) capability, and cyber-attack/fault detection. The network under study consists of two areas with different frequencies that are connected through one 300 km HVDC line. The proposed control system regulates the frequency in both areas by managing power through HVDC line. The converters on both sides of HVDC line are controlled to handle faults on the DC and AC sections as well as improving fault ride through capability. The control strategies are implemented and operated depending on fault/cyber-attack type and behaviour. In this respect, the control mechanism may change the firing angle of converters, switch their operating mode from rectifier to converter and vice-versa or even block the converters. The proposed paradigm successfully distinguishes between the cyber-attacks and faults. The simulations in MATLAB software validate that the proposed mechanism realizes all the objectives and the cyber-attacks are completely identified and separated from the faults.
