Improving Distribution System Performance through Static Compensation

Control of reactive power (VAR-control) in an electric power system serves three different purposes: 1. To maintain, if possible, unity power factor throughout the system, thus, minimizing reactive line flows and associated real power losses; 2. To maintain a stable and acceptable voltage profile in the system; 3. To maintain operating stability of the system\´s generators during major disturbances. These three control functions are interdependent. For example, maintaining minimum losses also tends to flatten the voltage profile. The paper presents the underlying concepts of VAR-control and discusses requirements of the reactive controller. Using this as background the features of an "ideal compensator" are defined and are related to the operation of a new system control device called the static VAR compensator (SVC).