The system stabilizing device

And to provide a possible suppression technique frequency change of the power. System stabilizing device 1, of the first generator 2a of multiple connected remote island system 5 and through the first communication system line 4a and the first battery 3a, a control command with respect to the first battery 3a do. System stabilizing device 1 comprises a parameter determination unit 11, a control block 21. Parameter determination unit 11 based on the operation information, determine the rate of change limit value indicating a restriction imposed on the sum of the output change of the entire first generator 2a during operation. The control block 21, on the basis the linking point power flow value measured in the first communication system line 4a, to the change rate limit value parameter determination unit 11 is determined, generating a command value to be given to the first battery 3a to.