High performance controlled switching vacuum circuit breaker enables fast reclosing on capacitor bank - breakthrough in reactive power compensation

Today the decentralized power generation (wind farms and photovoltaic plants) is growing more and more. Medium voltage capacitor banks are crucial to assure network stability, reliability, and reactive power compensation. The recent releases of high-performance synchronized vacuum circuit breakers for capacitor switching applications overcome technical challenges like inrush currents, prestrikes and restrikes. These features allow to extend the lifetime of the whole asset, manage the network reducing the need of components for mitigating transients and synergies with other technologies for managing loads transitions (e.g. Static VAR Compensator). This publication presents a breakthrough step of the circuit breaker functionality combining the transient-free and restrike-free functionality with a new fast-reclosing function eliminating the need of discharging time before re-energizing the capacitor bank. A medium voltage (MV) circuit breaker, with its embedded digital control and precise actuation system, is presented together with its capability to combine restrike-free open operation with transient-free close operation at any time, by adapting continuously the closing strategy based on measurements taken on the network and on the load. In this article, the circuit breaker concept and features are presented together with the performances of closing and opening operations performed at any status of charge of capacitor banks, in both simulations and laboratory tests.