Series and parallel switched inductors managing steady-state overvoltages in distribution grids with distributed generation

The rising amount of distributed generation (DG) connected to distribution grids may lead to overvoltages in steady-state. Reactive power provided by DG or inductors can reduce voltage. This paper investigates how series and parallel switched inductors can be used to reduce overvoltages at the medium voltage level. The issues of the inductor´s size and position are discussed. Fields of application and required devices for an operation are derived. The effects on voltage level and voltage stability are investigated. The economic benefit is evaluated by a comparison of possible efforts to manage overvoltages. A probabilistic approach was used. The results show that series switched inductors provide a flexible and cost-efficient solution. The parallel inductors are more expensive, but still cheaper than conventional grid reinforcements. Compared to series inductors, parallel inductors can be used independently from grid structures and the spread of DG in the distribution grid.