In　voltage　stability　analysis,　the　critical　points　of　static　voltage　stability　usually　correspond　to　simple　fold　points　of　power　flow　equations.　In　this　paper,　a　minimally　extended　system　method　was　introduced　to　calculate　simple　fold　points　of　power　flow　equations　with　sufficient　accuracy.　The　method　was　a　kind　of　numerical　methods　in　nonlinear　bifurcation　computing.　For　n-dimensional　parameter-dependent　power　flow　equations,　the　minimally　extended　system　for　locating　simple　fold　points　of　power　flow　equations　was　composed　of　original　power　flow　equations　and　a　scalar　equation　which　described　the　characteristics　of　simple　fold　points.　The　solution　of　the　bordered　linear　systems　required　in　Newton＇s　method　to　solve　the　minimally　extended　system　was　realized　by　block　elimination　algorithm,　thus　sparsity　of　Jacobian　matrix　of　power　flow　equations　could　be　fully　exploited　to　enhance　calculation　efficiency.　Compared　with　the　(2n　+　1)-dimensional　system　which　determines　simple　fold　points　of　power　flow　equations,　the　method　need　not　any　reduction　process,　and　right　and　left　eigenvectors　corresponding　to　the　zero　eigenvalue　of　Jacobian　matrix　of　power　flow　equations　at　simple　fold　points　could　also　be　obtained.　Numerical　examples　of　real　power　systems　were　presented　to　show　the　feasibility　and　validity　of　the　method.　©　2009　Chin.　Soc.　for　Elec.　Eng.