Patent ID: 9562939
Date: 2017-02-07
CPC Classifications: G01R

Claim:
1. A method of impedance measurement in a three-phase alternating current (AC) system, the method comprising: connecting a perturbation injector to the three-phase AC system, the perturbation injector comprising a voltage source inverter having a shunt injection circuit and a series injection circuit that are operable without active DC power addition; connecting by the perturbation injector the shunt injection circuit to the three-phase AC system; injecting by the shunt injection circuit a shunt perturbation signal into the three-phase AC system; collecting by a collection circuit of an impedance measurement unit a response to the shunt perturbation signal; switching by the perturbation injector from the shunt injection circuit to the series injection circuit; injecting by the series injection circuit a series perturbation signal into the three-phase AC system; collecting by the collection circuit of the impedance measurement unit a response to the series perturbation signal; transferring by an instrumentation platform computer the response to the shunt perturbation signal and the response to the series perturbation signal from three-phase (abc) coordinates to direct and quadrature (dq); and calculating by a control circuit at least one impedance of the three-phase AC system based on the response to the shunt perturbation signal and the response to the series perturbation signal.