The Voltage Sags Matrix: a Useful Tool for Power Quality Analysis

The paper proposes a simple approximated method for calculation of voltage sags in an electrical network. Following the general method for symmetrical (three-phase) fault calculations based on the use of the bus impedance matrix of the network, the paper illustrates the construction of a square matrix that, under acceptable assumptions, directly provides voltage drops (sags) at each node of the network and for each faulted node. This matrix, which may be called the voltage sags matrix of the network, gives a synthetic representation of sags produced by symmetrical faults for the overall network. Approximations introduced are discussed and different possible applications of the matrix are outlined.