The invention discloses a multichannel 
direct current added damping control device capable of simultaneously restraining sub-synchronization and 
low frequency oscillation, and a parameter setting method of the multichannel 
direct current added damping control device. The device is characterized in that the device identifies the subsynchronous oscillation, the 
low frequency oscilation frequency and the damping of a 
direct current under island running and a 
system reduced-order model on the basis of a 
matrix pencil algorithm which has high operation efficiency and anti-interference capacity, a multichannel direct current added damping controller is designed through a 
root locus method so as to reduce mutual effects between oscillation 
modes, and sub-synchronization and 
low frequency oscillation can be simultaneously restrained. 
Electric generator rotating speed signals are divided into 
multiple frequency bands according to results of analysis conducted on characteristics of 
system oscillation through the 
matrix pencil algorithm, a passageway corresponding to each 
frequency band can independently adjust the 
gain, the phase position, the output amplitude limit and the filter parameters, and therefore appropriate damping can be provided for sub-synchronization and 
low frequency oscillation in different frequency bands. The device is efficient and easy to obtain, and the function of simultaneously restraining sub-synchronization and 
low frequency oscillation through the direct current added damping controller is achieved for the first time in the 
high voltage direct current transmission field.