Power quality improvement in transmission and distribution networks via synchronous switching

Switching transients are a known source of power quality problems, not only for the switched load, but also for other network components. An effective technology for reduction of switching transients is the so-called "synchronous switching", that consists of controlling each pole of the circuit breaker individually in order to perform pre-defined switching strategies. The paper reports and discusses the results of laboratory tests performed on such devices in order to evaluate their capability to accurately control the target instant and their effectiveness to reduce transients. The tests refer to synchronous closing of capacitor banks and transformers carried out at MV level. Then, the impact of controlled closing on the power system is investigated with reference to switching operations at a HV/MV substation simulated through an ATP-EMTP model. Both experimental and simulation results are considered by means of significant quantities with respect to power quality perspective.