[en] The control systems proposed are designed for power control and neutron field stabilization of a power reactor. A regulator is used for each harmonics controlled. A harmonics detector summes up neutron detector signals with weights proportional to the harmonics values in the locations of detectors. The rods and detectors of the control system are common for all the regulators. The harmonics dynamics is analyzed. Terminology of the harmonic control is proposed. The efficiency of the control systems with respect to the RBMK-1000 and WWER-1000 reactors is proved by computer simulation