A New Voltage Compensation Philosophy for Dynamic Voltage Restorer to Mitigate Voltage Sags Using Three-Phase Voltage Ellipse Parameters

This paper introduces a series compensation philosophy to improve the voltage property of loads using three-phase voltage ellipse parameters intended for optimal utilization of a dynamic voltage restorer. The proposed approach relies on the instantaneous magnitude of voltage signals and functions by inserting a virtual equivalent impedance in series with the distribution feeder during voltage sags, compensating for the difference between faulty and nominal voltages. In addition, the definite mathematical derivations using iterative processes are properly used as an identification mark of the resultant rotating vector tracing an ellipse. The ellipse parameters including major axis, minor axis, and inclination angle are utilized to develop the proposed algorithm and hence, a set of generalized VA loading formulations calculating an optimal sizing with the minimum possible rating are presented. The uniqueness of dual VSCs connected with common dc-side is an attempt to formalize the topological structure keeping a higher level of compensation accuracy. A novel design and the corresponding algorithm are proposed and all possible scenarios concerning sag depth and phase jump are taken into consideration. MATLAB-based simulation results are discussed in detail to support the concept and the test is also performed to verify the effectiveness through real-time experimental laboratory.