A method of controlling a power plant, the power plant comprising a plurality of generators, comprising the steps of: over a time horizon during which a varying output occurs in at least one selected generator in the power plant, measuring output parameters of the at least one selected generator comprising reactive power and voltage; determining a relationship between the measured output parameters of the at least one selected generator, the relationship between the measured output parameters of the at least one selected generator being effective to estimate a short circuit ratio of a power grid to which the power plant supplies power; and controlling the power plant by a controller in a manner responsive to the relationship between the measured output parameters of the at least one selected generator, characterized in that controlling step comprising the steps of comparing the estimated short circuit ratio relative to a first predefined limit (Limit1), if the estimated short circuit ratio is above the first predefined limit (Limit1), setting the controller to operate in a normal control mode, if the estimated short circuit ratio is below first predefined limit (Limit1), further comparing the estimated short circuit ratio relative to a second predefined limit (Limit2), which is lower than the first predefined limit (Limit1), if the estimated short circuit ratio is above the second predefined limit (Limit2), setting the controller to operate in a weak grid control mode comprising adjusting control parameters in a power plant control algorithm to optimize performance of plant voltage regulation and power control of the power plant, if the estimated short circuit ratio is below the second predefined limit (Limit2), setting the controller to command the power plant to reduce power plant output. over a time horizon during which a varying output occurs in at least one selected generator in the power plant, measuring output parameters of the at least one selected generator comprising reactive power and voltage; determining a relationship between the measured output parameters of the at least one selected generator, the relationship between the measured output parameters of the at least one selected generator being effective to estimate a short circuit ratio of a power grid to which the power plant supplies power; and controlling the power plant by a controller in a manner responsive to the relationship between the measured output parameters of the at least one selected generator, controlling step comprising the steps of comparing the estimated short circuit ratio relative to a first predefined limit (Limit1), if the estimated short circuit ratio is above the first predefined limit (Limit1), setting the controller to operate in a normal control mode, if the estimated short circuit ratio is below first predefined limit (Limit1), further comparing the estimated short circuit ratio relative to a second predefined limit (Limit2), which is lower than the first predefined limit (Limit1), if the estimated short circuit ratio is above the second predefined limit (Limit2), setting the controller to operate in a weak grid control mode comprising adjusting control parameters in a power plant control algorithm to optimize performance of plant voltage regulation and power control of the power plant, if the estimated short circuit ratio is below the second predefined limit (Limit2), setting the controller to command the power plant to reduce power plant output.