VOLTAGE AND CURRENT MANAGEMENT IN THREE-PHASE INTERCONNECTED POWER SYSTEMS USING POSITIVE AND NEGATIVE SEQUENCE SECONDARY CONTROL

A method and apparatus for secondary control in a power network. In one embodiment, the method comprises determining a frequency area controller error (ACE) equation for an area and a voltage ACE for the area; decomposing the frequency ACE equation and the voltage ACE equation to generate a first set of symmetric sequences for the frequency ACE equation and a second set of symmetric sequences for the voltage ACE equation, respectively, wherein the first and second sets of symmetric sequences represent positive and negative sequences; and implementing, by an area controller for the area, secondary control on each sequence in the first and second sets of symmetric sequences separately.