Algorithm for Designing the Size of Energy Storage in Dynamic Voltage Restorer

A large capacity of the energy storage unit in a dynamic voltage restorer (DVR) may result in a significant cost of using DVR that may not be justified in the case where the number of severe voltage sags is extremely low over the lifespan of DVR. However, a significant reduction in the capacity of the energy storage unit may not guarantee that the voltage supply filtered by DVR is compatible with the sensitivity of the protected load. To achieve a balance between the compatibility and the cost saving of using DVR, an algorithm is developed and integrated with a voltage sag prediction method to derive two essential bar charts. By using these bar charts and the available voltage tolerance curve of the protected load, one can determine the optimum capacity of the energy storage unit that may ensure a balance between the compatibility and the maximum cost saving of using DVR