An improved simulation approach for the analysis of voltage flicker and the evaluation of mitigation strategies

An approach to the estimation of the severity of power system voltage flicker is presented in this paper. The presented technique is a simulation approach using a combined time/frequency-domain analysis technique. This hybrid approach allows the accuracy of differential equation-based mathematical models for critical components and the simplicity of phasor/impedance frequency-domain models for other components to be used in the same algorithm. Frequency-domain techniques are used to formulate a multi-phase power distribution system model to account for the effects of system unbalance. To incorporate the inherent temporal nature of the flicker problem, time-domain techniques are used to represent loads that produce flicker and the equipment that may be installed to mitigate flicker. A least-squares estimation technique developed for digital relaying applications is used as an "interface" between the time-domain differential equation solutions and the frequency-domain network solutions. Both peak-to-peak and RMS bus voltages are automatically generated by the algorithm and are shown to be accurate relative to EMTP software.