Ride-through for critical loads. Exploring a low-cost approach to maintaining continuous connections between buildings and/or industrial systems

A low-cost approach to provide ride-through capability for critical loads has been explored. The approach provides continuous power to the load under two operational modes. Normal mode allows the load to be connected directly from the utility power supply, as long as it remains undisturbed. Once a voltage sag appears, the load is transferred to an inverter that provides the ride-through mode. The output of the inverter is synchronized with the utility input and is regulated by keeping the DC-link voltage regulated, too. An external energy source can be incorporated in the DC-link to provide ride-through during short-term power interruptions. Results show that the detection of the disturbance is quick, and the transfer between operational modes is seamless, causing no evident problems to the load. High efficiency is only achieved by applying the ride-through operational mode during the disturbance duration. Reduced size and low cost are additional characteristics of the proposed approach.