Patent ID: 7280938

Claim:
A method for controlling an electrical network, the method comprising steps of: determining components of a space vector of a space vector quantity in an electrical network; determining the length of the space vector of the space vector quantity and its derivative; determining the zeros of said derivative; determining, based on said determined zeros of said derivative, the components of the major and minor semi-axes of the ellipse formed by the space vector of the space vector quantity; determining, based on said determined components of the major and minor semi-axes of the ellipse formed by the space vector, the magnitude of the negative sequence component of the space vector quantity and the location of the negative sequence component of the space vector quantity in relation to a positive sequence component, and controlling the electrical network by supplying in the electrical network a voltage whose voltage unbalance has been compensated based on said determined magnitude of the negative sequence component of the space vector quantity and said determined location of the negative sequence component of the space vector quantity in relation to a positive sequence component.