Patent ID: 8452462
Filing Date: 2013-05-28
Classification: G05B,H02J,Y02E

Abstract:
1. A system stabilizing device provided in a distribution system which, when a power system is normal, is connected to the power system, and when an abnormality occurs in the power system, is cut off from the power system, and to which a dispersed generation plant and a load are connected, the system stabilizing device having a control unit, and a power converter which performs a converting action and an inverting action in accordance with a gate signal fed from the control unit, wherein when the power system is normal, the control unit determines an active component of a system current and a reactive component of the system current, the system current flowing from the power system into the distribution system; determines a fluctuation component included in the active component of the system current by a first fluctuation detecting block, and uses the fluctuation component as a current command for the active component; determines a fluctuation component included in the reactive component of the system current by a second fluctuation detecting block, and uses the fluctuation component as a current command for the reactive component; further determines an active component of a converter current and a reactive component of the converter current, the converter current being inputted to and outputted from the power converter; and outputs the gate signal for reducing a current deviation for the active component, which is a deviation between the current command for the active component and the active component of the converter current, to zero, and also reducing a current deviation for the reactive component, which is a deviation between the current command for the reactive component and the reactive component of the converter current, to zero, and when the abnormality occurs in the power system, the control unit determines, from a system voltage of the distribution system, a frequency signal showing a frequency of the system voltage and an amplitude signal showing an amplitude of the system voltage; determines a fluctuation component included in the frequency signal by a third fluctuation detecting block, and uses the fluctuation component as a current command for an active component; determines a fluctuation component included in the amplitude signal by a fourth fluctuation detecting block, and uses the fluctuation component as a current command for a reactive component; further determines the active component of the converter current and the reactive component of the converter current, the converter current being inputted to and outputted from the power converter; and outputs the gate signal for reducing a current deviation for the active component, which is a deviation between the current command for the active component and the active component of the converter current, to zero, and also reducing a current deviation for the reactive component, which is a deviation between the current command for the reactive component and the reactive component of the converter current, to zero, the first to fourth fluctuation detecting blocks are each composed of a fluctuation detecting unit ( the fluctuation detecting unit ( the first current command creating unit ( the second current command creating unit (