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P-V and Q-V curves are commonly used to determine the steady state voltage stability limit of a power system. In this letter, a new method of determining the voltage stability limit using the P-Q curve is presented. The boundary of the voltage stability region is first determined and then presented in the P-Q plane. For a given operating point, the voltage stability margin can easily be determined from the stability boundary in the P-Q plane. The proposed method of determining the voltage stability limit was tested on a simple system and very interesting results were found.